Celyad Oncology (CLYYF) 20-F 25 Mar 20 2019 FY Annual report (foreign) Financial data

Cover

Cover	12 Months Ended
	Dec. 31, 2019shares
Statement [Line Items]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Document Annual Report	true
Document Transition Report	false
Document Shell Company Report	false
Entity Registrant Name	CELYAD S.A.
Entity Central Index Key	0001637890
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity Voluntary Filers	No
Entity Common Stock, Shares Outstanding	13,942,344
Entity Address, Country	BE
Title of 12(b) Security	Ordinary shares
Trading Symbol	CYAD
Security Exchange Name	NASDAQ

Consolidated Statements of Fina

Consolidated Statements of Financial Position - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018
Statement of financial position [abstract]
NON-CURRENT ASSETS	€ 47,000	€ 42,607
Intangible assets	36,199	36,164
Property, Plant and Equipment	5,061	3,014
Non-current Trade and Other receivables	2,432	1,743
Non-current Grant receivables	3,051	1,472
Other non-current assets	257	215
CURRENT ASSETS	42,836	51,692
Trade and Other Receivables	558	367
Grant receivables	1,686
Other current assets	1,253	1,585
Short-term investments	0	9,197
Cash and cash equivalents	39,338	40,542
TOTAL ASSETS	89,836	94,299
EQUITY	45,619	55,589
Share Capital	48,513	41,553
Share premium	43,349	206,149
Other reserves	28,181	25,667
Accumulated deficit	(74,424)	(217,778)
NON-CURRENT LIABILITIES	32,295	29,063
Bank loans	37	229
Lease liabilities	2,967	652
Recoverable Cash advances (RCAs)	4,139	2,864
Contingent consideration payable and other financial liabilities	24,754	25,187
Post employment benefits	398	131
Other non-current liabilities
CURRENT LIABILITIES	11,922	9,647
Bank loans	192	281
Lease liabilities	1,167	484
Recoverable Cash advances (RCAs)	346	276
Trade payables	6,969	5,916
Other current liabilities	3,248	2,690
TOTAL EQUITY AND LIABILITIES	€ 89,836	€ 94,299

Consolidated Statements of Inco

Consolidated Statements of Income (Loss) - EUR (€) € in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Profit or loss [abstract]
Revenue		€ 6	€ 3,115	€ 3,540
Cost of Sales				(515)
Gross profit		6	3,115	3,025
Research and Development expenses		(25,196)	(23,577)	(22,908)
General & Administrative expenses		(9,070)	(10,387)	(9,310)
Other income		5,572	1,078	2,630
Other expenses		(191)	(8,399)	(41)
Amendment of Celdara Medical and Dartmouth College agreements				(24,341)
Write-off C-Cure and Corquest assets and derecognition of related liabilities				(1,932)
Operating Loss		(28,879)	(38,170)	(52,876)
Financial income		582	804	933
Financial expenses		(343)	(62)	(4,454)
Loss before taxes		(28,640)	(37,428)	(56,396)
Income taxes		8	0	1
Loss for the period	[1]	€ (28,632)	€ (37,427)	€ (56,395)
Weighted average number of shares outstanding		12,523,166	11,142,244	9,627,601
Basic and diluted loss per share (in €)		€ (2.29)	€ (3.36)	€ (5.86)
[1]	For 2019 and 2018, the Company does not have any non-controlling interests and the losses for the year are fully attributable to owners of the parent.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income / (Loss) - EUR (€) € in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of comprehensive income [abstract]
Loss for the period	[1]	€ (28,632)	€ (37,427)	€ (56,395)
Other comprehensive (loss)
Items that will not be reclassified to profit and loss		(301)	70
Remeasurements of post-employment benefit obligations, net of tax		(301)	70
Items that may be subsequently reclassified to profit or loss		(261)	(1,194)	(769)
Currency translation differences		(261)	(1,194)	(769)
Other comprehensive loss for the period, net of tax		(562)	(1,124)	(769)
Total comprehensive loss for the period		(29,194)	(38,551)	(57,164)
Total comprehensive loss for the period attributable to Equity Holders		€ (29,194)	€ (38,551)	€ (57,164)
[1]	For 2019 and 2018, the Company does not have any non-controlling interests and the losses for the year are fully attributable to owners of the parent.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - EUR (€) € in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flow from operating activities
Loss for the period	[1]	€ (28,632)	€ (37,427)	€ (56,395)
Non-cash adjustments
Intangibles—Amortization and impairment		169	66	8,038
Property, plant & equipment—Depreciation		1,619	1,048	966
Upfront payment settled in shares			(843)
Non-Cash expense for amendment of Celdara Medical and Dartmouth College agreements				10,620
Fair value adjustment on securities		(182)
Change in fair value of contingent consideration payable and other financial liabilities		(433)	5,604	(193)
Remeasurement of Recoverable Cash Advances (RCA's)		120	998	(5,356)
Grant income (RCA's and others)		(3,296)	(768)	(1,376)
Loss on disposal of property, plant and equipment		0
Share-based payment expense		2,775	3,595	2,569
Post-Employment benefits		267	(3)
Change in working capital
Trade receivables, other (non-)current receivables		(1,772)	(1,459)	(832)
Trade payables, other (non-)current liabilities		1,163	1,940	(2,482)
Net cash used in operations		(28,202)	(27,249)	(44,441)
Cash Flow from investing activities
Acquisition of Property, Plant & Equipment		(417)	(833)	(851)
Acquisitions of Intangible assets		(205)	(932)	(7)
Disposals of fixed assets		0	74
Proceeds from net investment in lease		230
Contingent liability pay-out				(5,107)
Acquisition of short term investments			(26,561)	(10,749)
Proceeds from short term investments		9,379	28,859	34,327
Net cash from/(used in) investing activities		8,987	607	17,613
Cash Flow from financing activities
Proceeds from bank borrowings			220
Repayments of bank borrowings		(281)	(246)	(207)
Proceeds from leases		0	730	542
Repayments of leases		(1,206)	(503)	(369)
Proceeds from issuance of shares and exercise of warrants		16,448	43,011	625
Proceeds from RCAs & other grants		3,571	1,187	1,376
Repayments of RCAs & other grants		(256)	(471)	(1,364)
Net cash from/(used in) financing activities		18,276	43,928	605
Net cash and cash equivalents at beginning of the period		40,542	23,253	48,357
Change in Cash and cash equivalents		(939)	17,286	(26,224)
Effects of exchange rate changes on cash and cash equivalents		(265)	3	1,120
Net cash and cash equivalents at the end of the period		€ 39,338	€ 40,542	€ 23,253
[1]	For 2019 and 2018, the Company does not have any non-controlling interests and the losses for the year are fully attributable to owners of the parent.

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - EUR (€) € in Thousands	Total		Share capital [member]	Share premium [member]	Other reserves [member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2016	€ 90,885		€ 32,571	€ 158,010	€ 24,330	€ (124,026)
Capital increase resulting from Celdara and Dartmouth College agreements amendment	10,620		1,141	9,479
Exercise of warrants	625		625
Share-based payments	2,569			2,808	(239)
Total transactions with owners, recognized directly in equity	13,814		1,766	12,287	(239)
Loss for the period	(56,395)	[1]				(56,395)
Currency translation differences	(769)				(769)
Total comprehensive loss for the period	(57,164)				(769)	(56,395)
Ending balance at Dec. 31, 2017	47,535		34,337	170,297	23,322	(180,421)
Capital increase in cash	46,140		7,204	38,937
Transaction costs associated with capital increases	(3,141)			(3,141)
Exercise of warrants	12		12
Share-based payments	3,595			56	3,539
Total transactions with owners, recognized directly in equity	46,606		7,215	35,851	3,539
Loss for the period	(37,427)	[1]				(37,427)
Currency translation differences	(1,194)				(1,194)
Remeasurements of defined benefit obligation	70					70
Total comprehensive loss for the period	(38,551)				(1,194)	(37,357)
Ending balance at Dec. 31, 2018	55,589		41,553	206,149	25,667	(217,778)
Capital increase in cash	18,169		6,960	11,209
Transaction costs associated with capital increases	(1,721)			(1,721)
Share-based payments	2,775				2,775
Total transactions with owners, recognized directly in equity	19,223		6,960	9,488	2,775
Loss for the period	(28,632)	[1]				(28,632)
Currency translation differences	(261)				(261)
Reduction of share premium by absorption of losses				172,287		172,287
Remeasurements of defined benefit obligation	(301)					(301)
Total comprehensive loss for the period	(29,194)			(172,287)	(261)	143,354
Ending balance at Dec. 31, 2019	€ 45,619		€ 48,513	€ 43,349	€ 28,181	€ (74,424)
[1]	For 2019 and 2018, the Company does not have any non-controlling interests and the losses for the year are fully attributable to owners of the parent.

The Company

The Company	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
The Company	NOTE 1: THE COMPANY The Company is a clinical-stage biopharmaceutical company focused on the development of specialized CAR-T CAR-T The Company’s lead clinical candidate, CYAD-01, CAR-T CYAD-101, non-gene CAR-T Celyad SA was incorporated on July 24, 2007 under the name “Cardio3 BioSciences”. Celyad SA is a limited liability company (Société Anonyme) governed by Belgian law with its registered office at Axis Parc, Rue Edouard Belin 2, B-1435 The Company has three fully owned subsidiaries (together, the Group) located in Belgium (Biological Manufacturing Services SA) and in the United States (Celyad Inc. and CorQuest Medical, Inc.). OnCyte LLC was dissolved on March 8, 2018 and, as a result, all its assets and liabilities were fully distributed to and assumed by Celyad SA. These consolidated financial statements have been approved for issuance by the Company’s Board of Directors on March 24, 2020. These statements have been audited by BDO Réviseurs d’Entreprises SCRL, the statutory auditor of the Company and independent registered public accounting firm. The annual report is available to the public free of charge and upon request to the above-mentioned address or via the Company’s website ( http://www.celyad.com/investors

General information and Stateme

General information and Statement of Compliance	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
General information and Statement of Compliance	NOTE 2: GENERAL INFORMATION AND STATEMENT OF COMPLIANCE The year-end Basis of preparation The consolidated financial statements have been prepared on a historical cost basis, except for: • Financial instruments – Fair value through profit or loss • Contingent consideration and other financial liabilities • Post-employment benefits liability • Equity securities held as short-term investments at 31 December 2019 (see note 13) The policies have been consistently applied to all the years presented, unless otherwise stated. The consolidated financial statements are presented in euro and all values are presented in thousands (€000) except when otherwise indicated. Amounts have been rounded off to the nearest thousand and in certain cases, this may result in minor discrepancies in the totals and sub-totals Statement of compliance The consolidated financial statements of the Company have been prepared in accordance with International Financial Reporting Standards, International Accounting Standards and Interpretations (collectively, IFRSs) as issued by the International Accounting Standards Board (IASB) and as endorsed by the European Union. The preparation of the consolidated financial statements in accordance with IFRS requires the use of certain critical accounting estimates. It also requires management to exercise its judgment in the process of applying the Company’s accounting policies. The areas involving a higher degree of judgment or complexity, are areas where assumptions and estimates are significant to the financial statements. They are disclosed in note 5. Going concern 2 The Company is pursuing a strategy to develop therapies to treat unmet medical needs in oncology. Management has prepared detailed budgets and cash flow forecasts for the years 2020 and 2021. These forecasts reflect the strategy of the Company and include significant expenses and cash outflows in relation to the development of selected research programs and product candidates. Based on its current scope of activities, the Company estimates that its treasury position 3 Changes to accounting standards and interpretations The Company has applied the same accounting policies and methods of computation in its year-end Leases IFRS 16 standard replaces the former lease accounting requirements and, in particular, represents a significant change in the accounting and reporting of leases that were previously classified as ‘operating leases’ under IAS 17, with incremental assets and liabilities to be reported on the balance sheet and a different recognition basis for lease costs. The details of the changes in accounting policies and the transition quantitative impact are discussed further under the note 3. None of the other new or amended standards and interpretations issued by the IASB and the IFRIC that will apply for the first time in future annual periods are expected to have a material effect on the Group as either they are not relevant to the Group’s activities or they require accounting which is consistent with the Group’s current accounting policies.

Accounting Principles

Accounting Principles	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Accounting Principles	NOTE 3: ACCOUNTING PRINCIPLES Subsidiaries Subsidiaries are all entities (including structured entities) over which the Group has control. The Group controls an entity when the Group is exposed to, or has rights to, variable returns from its involvement with the entity and 2 The uncertainly raised by the COVID-19 3 ‘Treasury position’ is an alternative performance measure determined by adding Short-term investments and Cash and cash equivalents from the statement of financial position prepared in accordance with IFRS. has the ability to affect those returns through its power over the entity. Subsidiaries are fully consolidated from the date on which control is transferred to the Group. They are deconsolidated from the date control ceases. Inter-company transactions, balances and unrealized gains on transactions between group companies are eliminated. Unrealized losses are also eliminated. When necessary, amounts reported by subsidiaries have been adjusted to conform with the Group’s accounting policies. Business Combinations The Group applies the acquisition method to account for business combinations. The consideration transferred for the acquisition of a subsidiary is measured at the aggregate of the fair values of the assets transferred, the liabilities incurred or assumed, and the equity interests issued by the Group at the date of the acquisition. The consideration transferred includes the fair value of any asset or liability resulting from a contingent consideration arrangement. Identifiable assets acquired and liabilities and contingent liabilities assumed in a business combination are measured initially at their fair values at the acquisition date. Acquisition-related costs are expensed as incurred. Any contingent consideration to be transferred by the Group is recognized at fair value at the acquisition date. Subsequent changes to the fair value of the contingent consideration that is deemed to be an asset or liability is recognized in profit or loss, in accordance with IFRS 9 if applicable. Contingent consideration that is classified as equity is not re-measured, FOREIGN CURRENCY TRANSLATION Functional and presentation currency Items included in the financial statements of each of the Group’s entities are measured using the currency of the primary economic environment in which the entity operates (“the functional currency”). The consolidated financial statements are presented in Euros, which is the Group’s presentation currency. Transactions and balances Foreign currency transactions (mainly USD) are translated into the functional currency using the applicable exchange rate on the transaction dates. Monetary assets and liabilities denominated in foreign currencies are retranslated at the functional currency spot rate of exchange ruling at the reporting date. Foreign currency exchange gains and losses arising from settling foreign currency transactions and from the retranslation of monetary assets and liabilities denominated in foreign currencies at the reporting date are recognized in the income statement. Non-monetary Non-monetary Group companies The results and financial position of all group entities that have a functional currency different from the presentation currency are translated into the presentation currency as follows: • Assets and liabilities for each balance sheet presented are translated at the closing rate at the date of that balance sheet; • Income and expenses for each income statement are translated at average exchange rate (unless this average is not a reasonable approximation of the cumulative effect of the rates prevailing on the transaction dates, in which case income and expenses are translated at the rate on the dates of the transactions); and • All resulting translation differences are recognized in other comprehensive income. REVENUE So far, the main revenue generated by the Group relates to the sale of licenses. Licensing revenue The Group enters into license and/or collaboration agreements with third-party biopharmaceutical partners. Revenue under these arrangements may include non-refundable Upfront payments License fees representing non-refundable Milestone payments Milestone payments represent amounts received from the Group’s customers or collaborators. The receipt of which is dependent upon the achievement of certain scientific, regulatory, or commercial milestones. Under IFRS 15, milestone payments generally represent a form of variable consideration as the payments are likely to be contingent on the occurrence of future events. Milestone payments are estimated and included in the transaction price based on either the expected value (probability-weighted estimate) or most likely amount approach. The most likely amount is likely to be most predictive for milestone payments with a binary outcome (i.e., the Group receives all or none of the milestone payment). Variable consideration is only recognized as revenue when the related performance obligation is satisfied, and the Group determines that it is highly probable that there will not be a significant reversal of cumulative revenue recognized in future periods. Royalty revenue Royalty revenues arise from the Group’s contractual entitlement to receive a percentage of product sales achieved by co-contracting co-contracting Sales of goods (medical devices) Sales of medical devices are recognized when the Group has fulfilled the performance obligations under the terms of the sales contract, which includes delivery of the promised goods. Sales of medical devices generated by the Group until 2017 are associated with C-Cath ez GOVERNMENT GRANTS (OTHER OPERATING INCOME ) The Group’s grant income reported under ‘Other income’ in the consolidated income statement is generated from: (i) recoverable cash advances (RCAs) granted by the Regional government of Wallonia; (ii) R&D tax credits granted by the Belgian federal government; and (iii) grants received from the European Commission under the Seventh Framework Program (“FP7”) and from Regional authorities. Government grants are recognized at their fair value where there is reasonable assurance that the grant will be received, and the Group will comply with all attached conditions. Once a government grant is recognized, any related contingent liability (or contingent asset) is treated in accordance with IAS 37. Government grants relating to costs are deferred and recognized in the income statement over the period necessary to match them with the costs that they are intended to compensate. Recoverable cash advances (RCAs) The Group receives grants from the Walloon Region in the form of recoverable cash advances (RCAs). RCAs are dedicated to support specific development programs. All RCA contracts, in essence, consist of three phases, i.e., the “research phase”, the “decision phase” and the “exploitation phase”. During the research phase, the Group receives funds from the Region based on statements of expenses. In accordance with IAS 20.10A and IFRS Interpretations Committee (IC)’s conclusion that contingently repayable cash received from a government to finance a research and development (R&D) project is a financial liability under IAS 32, ‘Financial instruments; Presentation’, the RCAs are initially recognized as a financial liability at fair value, determined as per IFRS 9/IAS 39. The benefit (RCA grant component) consisting in the difference between the cash received (RCA proceeds) and the above-mentioned financial liability’s fair value (RCA liability component) is treated as a government grant in accordance with IAS 20. The RCA grant component is recognized in profit or loss on a systematic basis over the periods in which the entity recognizes the underlying R&D expenses subsidized by the RCA. The RCAs liability component (RCA financial liability) is subsequently measured at amortized cost using the cumulative catch-up At the end of the research phase, the Group should within a period of six months decide whether or not to exploit the results of the research phase (decision phase). The exploitation phase may have a duration of up to 10 years. In the event the Group decides to exploit the results under an RCA, the relevant RCA becomes contingently refundable, and the fair value of the RCA liability adjusted accordingly, if required. When the Group does not exploit (or ceases to exploit) the results under an RCA, it has to notify the Region of this decision. This decision is of the sole responsibility of the Group. The related liability is then discharged by the transfer of such results to the Region. Also, when the Group decides to renounce to its rights to patents which may result from the research, title to such patents will be transferred to the Region. In that case, the RCA liability is extinguished. R&D Tax credits Since 2013, the Group applies for R&D tax credit, a tax incentive measure for European SME’s set-up Considering that R&D tax credits are ultimately paid by the public authorities, the related benefit is treated as a government grant under IAS 20 and booked into other income, in order to match the R&D expenses subsidized by the grant. Other government grants The Group has received and will continue to apply for grants from European (FP7) and Regional authorities. These grants are dedicated to partially finance early stage projects such as fundamental research, applied research, prototype design, etc. To date, all grants received are not associated with any conditions. As per each grant contract, grants are paid upon submission by the Group of a statement of eligible expenses. The Group incurs project expenses first and asks for partial refunding according to the terms of the contracts. These government grants are recognized in profit or loss on a systematic basis over the periods in which the entity recognizes the underlying R&D expenses subsidized. INTANGIBLE ASSETS The following categories of intangible assets apply to the current Group operations: Separately acquired intangible assets Intangible assets acquired from third parties are recognized at cost, if and only if it is probable that future economic benefits associated with the asset will flow to the Group, and that the cost can be measured reliably. Following initial recognition, intangible assets are carried at cost less any accumulated amortization and accumulated impairment losses. The useful life of intangible assets is assessed as finite, except for Goodwill and IPRD assets (discussed below). They are amortized over the expected useful economic life and assessed for impairment whenever there is an indication that the intangible asset may be impaired. The amortization period and the amortization method for an intangible asset with a finite useful life are reviewed at least at each financial year end. Changes in the expected useful life or the expected pattern of consumption of future economic benefits embodied in the asset is accounted for by changing the amortization period or method, as appropriate, and are treated as changes in accounting estimates. The amortization expense on intangible assets with finite lives is recognized in the income statement in the expense category consistent with the function of the intangible asset. Patents, Licenses and Trademarks Licenses for the use of intellectual property are granted for a period corresponding to the intellectual property of the assets licensed. Amortization is calculated on a straight-line basis over this useful life. Patents and licenses are amortized over the period corresponding to the IP protection and are assessed for impairment whenever there is an indication these assets may be impaired. Indication of impairment is related to the value of the patent demonstrated by the pre-clinical Software Software only concerns acquired computer software licenses. Software is capitalized on the basis of the costs incurred to acquire and bring to use the specific software. These costs are amortized over their estimated useful lives of three to five years on a straight-line basis. Intangible assets acquired in a business combination Goodwill Goodwill is an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Goodwill is measured as a residual at the acquisition date, as the excess of the fair value of the consideration transferred and the assets and liabilities recognized (in accordance with IFRS 3). Goodwill has an indefinite useful life and is not amortized but tested for impairment at least annually or more frequently whenever events or changes in circumstances indicate that goodwill may be impaired, as set forth in IAS 36 (Impairment of Assets). Goodwill arising from business combinations is allocated to cash generating units, which are expected to receive future economic benefits from synergies that are most likely to arise from the acquisition. These cash generating units form the basis of any future assessment of impairment of the carrying value of the acquired goodwill. In-process The In-process Subsequent R&D expenditure can be capitalized as part of the IPRD only to the extent that IPRD is in development stage, i.e. when such expenditure meets the recognition criteria of IAS 38. In line with biotech industry practice, the Group determines that ‘development stage’ under IAS 38 is reached when the product candidate gets regulatory approval (upon Phase III completion). Therefore, any R&D expenditure incurred between the acquisition date and the development stage should be treated as part of research phase and expensed periodically in the income statement. Internally generated intangible assets Except qualifying development expenditure (discussed below), internally generated intangible assets are not capitalized. Expenditure is reflected in the income statement in the year in which the expenditure is incurred. Research and development costs Research costs are expensed as incurred. Development expenditures on an individual project are recognized as an intangible asset when the Group can demonstrate: a) the technical feasibility of completing the intangible asset so that it will be available for use or sale. b) its intention to complete the intangible asset and use or sell it. c) its ability to use or sell the intangible asset. d) how the intangible asset will generate probable future economic benefits. Among other things, the entity can demonstrate the existence of a market for the output of the intangible asset or the intangible asset itself or, if it is to be used internally, the usefulness of the intangible asset. e) the availability of adequate technical, financial and other resources to complete the development and to use or sell the intangible asset. f) its ability to measure reliably the expenditure attributable to the intangible asset during its development. For the industry in which the Group operates, the life science industry, criteria a) and d) tend to be the most difficult to achieve. Experience shows that in the Biotechnology sector technical feasibility of completing the project is met when such project completes successfully Phase III of its development. For medical devices this is usually met at the moment of CE marking. Following initial recognition of the development expenditure as an asset, the cost model is applied requiring the asset to be carried at cost less any accumulated amortization and accumulated impairment losses. Amortization of the asset begins when development has been completed and the asset is available for use. It is amortized over the period of expected future benefit. Amortization is recorded in Research & Development expenses. During the period of development, the asset is tested for impairment annually, or earlier when an impairment indicator occurs. As of balance sheet date, only the development costs of C-Cath ez PROPERTY, PLANT AND EQUIPMENT Plant and equipment are stated at cost, net of accumulated depreciation and/or accumulated impairment losses, if any. Repair and maintenance costs are recognized in the income statement as incurred. Depreciation is calculated on a straight-line basis over the estimated useful life of the asset as follows: • Land and buildings: 15 to 20 years • Plant and equipment: 5 to 15 years • Laboratory equipment: 3 to 5 years • Office furniture: 3 to 10 years • Leasehold improvements: based on remaining duration of office building lease • Right-of-use An item of property, plant and equipment and any significant part initially recognized is derecognized upon disposal or when no future economic benefits are expected from its use or disposal. Any gain or loss arising on derecognition of the asset (calculated as the difference between the net disposal proceeds and the carrying amount of the asset) is included in the income statement when the asset is derecognized. The assets’ residual values, useful lives and methods of depreciation are reviewed at each financial year end, and adjusted prospectively, if applicable. LEASES The determination of whether an arrangement is, or contains, a lease is based on the substance of the arrangement at inception date whether fulfilment of the arrangement is dependent on the use of a specific asset or assets or the arrangement conveys a right to use the asset. The Group leases various offices, facilities, cars and IT-equipment. Until the 2018 financial year, leases of property, plant and equipment were classified as either finance or operating leases. Payments made under operating leases (net of any incentives received from the lessor) were charged to profit or loss on a straight-line basis over the period of the lease. From 1 January 2019, leases are recognized as a right-of-use right-of-use Assets and liabilities arising from a lease are initially measured on a present value basis. Lease liabilities include the net present value of the following lease payments: • fixed payments (including in-substance • variable lease payment that are based on an index or a rate; • amounts expected to be payable by the lessee under residual value guarantees; • the exercise price of a purchase option if the lessee is reasonably certain to exercise that option; and • payments of penalties for terminating the lease, if the lease term reflects the lessee exercising that option. The lease term covers the non-cancellable (a) periods covered by an option to extend the lease if the Group is reasonably certain to exercise that option; and (b) periods covered by an option to terminate the lease if the Group is reasonably certain not to exercise that option. The lease payments are discounted using the interest rate implicit in the lease. If that rate cannot be determined, the lessee’s incremental borrowing rate is used, being the rate that the lessee would have to pay to borrow the funds necessary to obtain an asset of similar value in a similar economic environment with similar terms and conditions. Right-of-use • the amount of the initial measurement of lease liability; • any lease payments made at or before the commencement date less any lease incentives received; • any initial direct costs; and • restoration costs. Payments associated with short-term leases and leases of low-value Low-value IT-equipment. The Group subleases some office space it leases from a head lessor. In its capacity as intermediate lessor, the Group assesses whether the sublease is a finance or operating lease in the context of the right-of-use right-of-use right-of-use From time to time, the Group may enter into sale and leaseback transactions. When a sale occurs, both the seller-lessee and the buyer-lessor account for the leaseback in the same manner as any other lease. Specifically, the seller-lessee recognizes a lease liability and right-of-use low-value Adjustments recognized on adoption of IFRS 16 The Group has adopted IFRS 16 modified retrospective approach from January 1, 2019 but has not restated comparatives for the 2018 reporting period, as permitted under the specific transitional provisions in the standard. The reclassifications and the adjustments arising from the new lease accounting principles are therefore recognized in the opening balance sheet on January 1, 2019. On adoption date, lease liabilities were measured at the present value of the remaining lease payments, discounted at the Group’s incremental borrowing rate as at 1 January 2019 (weighted-average rate applied was 7.5%). The right-of-use right-of-use The Group used the following practical expedients when applying IFRS 16 to leases previously classified as operating leases under IAS 17: • application of a single discount rate to a portfolio of lease with similar characteristics; • exclusion of initial direct costs from measuring the right-of-use • use of hindsight when determining the lease term if the contract contains options to extend or terminate the lease. On January 1, 2019, the Group recognized an additional lease liability of €3.9 million primarily relating to its headquarter offices as well as R&D and manufacturing facilities, and an increase in right-of-use The transition impact is detailed as follows: (€’000) Operating leases commitments disclosed—31 December 2018 2,912 Future minimum sublease income offset against amount of operating lease commitments previously disclosed [1] 1,078 Adjustment as a result of different treatment of extension options 957 ‘Low-value [2] (137 ) Operating leases commitments as per IFRS 16 scope 4,810 Discounting effect incremental borrowing rate (928 ) IFRS 16 lease liability (discounted) recognized at transition date—1 January 2019 3,882 IFRS 16 lease liability (non-current)—1 3,208 IFRS 16 lease liability (current)—1 January 2019 674 [1] This relates to a real estate property lease in which the Group acts as an intermediate lessor between a head lessor and a sublessee. [2] IFRS 16 scope exemptions, as commented above. IMPAIRMENT OF NON-FINANCIAL The Group assesses at each reporting date whether there is an indication that an asset may be impaired. If any indication exists, or when annual impairment testing for an asset is required, the Group estimates the asset’s recoverable amount. An asset’s recoverable amount is the higher of an asset’s or cash-generating unit’s (CGU) fair value less costs to sell and its value in use and is determined for an individual asset, unless the asset does not generate cash inflows that are largely independent of those from other assets or group of assets. In assessing value in use, the estimated future cash flows are discounted to their present value using a pre-tax cash-flow Where the carrying amount of an asset or CGU exceeds its recoverable amount, an impairment loss is immediately recognized as an expense and the asset carrying value is written down to its recoverable amount. An assessment is made at each reporting date as to whether there is any indication that previously recognized impairment losses may no longer exist or may have decreased. If such indication exists, the Group estimates the asset’s or cash-generating unit’s recoverable amount. A previously recognized impairment loss is reversed only if there has been a change in the assumptions used to determine the asset’s recoverable amount since the last impairment loss was recognized. The reversal is limited so that the carrying amount of the asset does not exceed its recoverable amount, nor exceed the carrying amount that would have been determined, net of depreciation, had no impairment loss been recognized for the asset in prior years. Such reversal is recognized in the income statement unless the asset is carried at a revalued amount, in which case the reversal is treated as a revaluation increase. An impairment loss recognized on goodwill is however not reversed in a subsequent period. As of balance sheet date, the Group has two cash-generating units which consist of the development and commercialization activities on: • CYAD products candidate series based on CAR-T • C-Cath ez Indicators of impairment used by the Group are the pre-clinical CASH AND CASH EQUIVALENTS Cash and cash equivalents in the statement of financial position comprise cash at banks and on hand and very short-term deposits with an original maturity of one month or less. Cash and cash equivalents are carried in the balance sheet at their nominal value. FINANCIAL ASSETS Classification The Group classifies its financial assets in accordance with IFRS 9 categories for measurement purposes. The classification depends on the purpose for which the financial assets were acquired. Management determines the classification of its financial assets at initial recognition. ‘Amortized cost’ measurement category refers to loans and receivables which are non-derivative non-current “(non-) “(non-) (non-) Initial recognition and measurement All financial assets are recognized initially at fair value plus or minus, in the case of a financial asset not at fair value through profit or loss, directly attributable transaction costs. Subsequent measurement After initial measurement, financial assets are subsequently measured at amortized cost using the effective interest rate method (EIR), less impairment. Amortized cost is calculated by taking into account any discount or premium on acquisition and fee or costs that are an integral part of the EIR. The EIR amortization is included in finance income in the income statement. The losses arising from impairment are recognized in the income statement. Impairment of financial assets In relation to the impairment of financial assets, IFRS 9 requires an expected credit loss model. The expected credit loss model requires the Group to account for expected credit losses and changes in those expected credit losses at each reporting date to reflect changes in credit risk since initial recognition of the financial assets. In other words, it is no longer necessary for a credit event to have occurred before credit losses are recognized. Specifically, IFRS 9 requires the Group to recognize a loss allowance for expected credit losses on trade receivables and contract assets. In particular, IFRS 9 requires the Group to measure the loss allowance for a financial instrument at an amount equal to the lifetime expected credit losses (ECL) if the credit risk on that financial instrument has increased significantly since initial recognition, or if the financial instrument is a purchased or originated credit-impaired credit-impaired 12-months Given the current nature and size of operations of the Group, these requirements mainly apply to the financial assets reported under ‘non-current Financial assets carried at amortized cost For financial assets carried at amortized cost the Group first assesses individually whether objective evidence of impairment exists individually for financial assets that are individually significant, or collectively for financial assets that are not individually significant. If the Group determines that no objective evidence of impairment exists for an individually assessed financial asset, it includes the asset in a group of financial assets with similar credit risk characteristics and collectively assesses them for impairment. Assets that are individually assessed for impairment and for which an impairment loss is, or continues to be, recognized are not included in a collective assessment of impairment. If there is objective evidence that an impairment loss has incurred, the amount of the loss is measured as the difference between the asset’s carrying amount and the present value of estimated future cash flows. The present value of the estimated future cash flows is discounted at the financial assets’ original effective interest rate. If a loan has a variable interest rate, the discount rate for measuring any impairment loss is the current effective interest rate. The carrying amount of the asset is reduced through the use of an allowance account and the amount of the loss is recognized in the income statement. Interest income continues to be accrued on the reduced carrying amount and is accrued using the rate of interest used to discount the future cash flows for the purpose of measuring the impairment loss. The interest income is recorded as part of finance income in the income statement. Loans together with the associated allowance are written off when there is no realistic prospect of future recovery. If, in a subsequent year, the amount of the estimated impairment loss increases or decreases because of an event occurring after the impairment was recognized, the previously recognized impairment loss is increased or reduced by adjusting the allowance account. If a future write-off FINANCIAL LIABILITIES Classification The Group’s financial liabilities include “bank loans”, “lease liabilities”, “recoverable cash advances”, “contingent consideration and other financial liabilities”, “trade payables” and relevant financial liabilities within “Other (non-) The Group classifies and measures its financial liabilities at ‘amortized cost’ using the effective interest method, except “contingent consideration and other financial liabilities” which are classified and measured at ‘fair value through profit or loss’. Initial recognition and measurement All financial liabilities are recognized initially at fair value plus or minus, in the case of a financial liabilities not at fair value through profit or loss, directly attributable transaction costs. Subsequent measurement The subsequent measurement of financial liabilities depends on their classification as explained above. In particular: Contingent consideration The contingent consideration and other financial liabilities are recognized and measured at fair value at the acquisition date. After initial recognition, contingent consideration arrangements that are classified as liabilities are re-measured Details regarding the valuation of the contingent consideration are disclosed in Note 22. Recoverable cash advances Recoverable cash advances granted by the Walloon Region are subsequently measured at amortized cost using the cumulative catch-up Trade payables and other payables After initial recognition, trade payables and other payables are measured at amortized cost using the effective interest method. Loans and borrowings After initial recognition, interest bearing loans and borrowings are subsequently measured at amortized cost using the effective interest rate method. Gains and losses are recognized in the income statement when the liabilities are derecognized. Amortized cost is calculated by taking into account any discount or premium on acquisition and fee or costs that are an integral part of the EIR. The EIR amortization is included in finance expense in the income statement. Derecognition A financial liability is derecognized when the obligation under the liability is discharged or cancelled or expires. When an existing financial liability is replaced by another from the same lender on substantially different terms, or the terms of an existing liability are substantially modified, such an exchange or modification is treated as a derecognition of the original liability and the recognition of a new liability, and the difference in the respective carrying amounts is recognized in the income statement. PROVISIONS Provisions are recognized when the Group has a present obligation (legal or constructive) as a result of a past event, it is probable that an outflow of resources embodying economic benefits will be required to settle the obligation and a reliable estimate can be made of the amount of the obligation. Where the Group expects some or all of a provision to be reimbursed, for example under an insurance contract, the reimbursement is recognized as a separate asset but only when the reimbursement is virtually certain. The expense relating to any provision is presented in the income statement net of any reimbursement. If the effect of the time value of money is material, provisions are discounted using a current pre-tax Employee benefits Post-employment plan The Group operates a pension plan which requires defined contributions (DC) to be funded by the Group externally at a third-party insurance company. Under Belgian law, an employer must guarantee a minimum rate of return on the Group’s contributions. Therefore, any pension plan (including DC plans) organized in Belgium is treated as defined benefit plans under IAS 19. At balance sheet date, the minimum rates of return guaranteed by the Group are as follows, in accordance with the law of 18 December 2015: • 1.75% for the employer’s contributions paid as from 1 January 2016 (variable rate based on G

Risk Management

Risk Management	12 Months Ended
	Dec. 31, 2019
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Risk Management	NOTE 4: RISK MANAGEMENT Financial risk factors Interest rate risk The interest rate risk is very limited as the Group has only a limited amount of finance leases and outstanding bank loans. So far, because of the immateriality of the exposure, the Group did not enter into any interest hedging arrangements. Credit risk The Group has a limited amount of trade receivables due to the fact that sales to third parties are not significant and thus the Group’s credit risk arises mainly from cash and cash equivalents and deposits with banks and financial institutions. The Group only works with international reputable commercial banks and financial institutions. Foreign exchange risk The Group is exposed to foreign exchange risk as certain collaborations or supply agreements of raw materials are denominated in USD. Moreover, the Group has also investments in foreign operations, whose net assets are exposed to foreign currency translation risk (USD). So far, because of the immateriality of the exposure the Group did not enter into any currency hedging arrangements. At year-end, EUR/USD foreign (loss)/gain exposure +2% +1% -1% -2% 31 December 2019 (€0.1 million) (€0.1 million) +€0.1 million +€0.1 million 31 December 2018 (€0.2 million) (€0.1 million) +€0.1 million +€0.2 million A depreciation of 1% on the USD versus EUR would translate into an unrealized foreign exchange loss of €60k for the Group at December 31, 2019. Liquidity risk The Group is pursuing a strategy to develop therapies to treat unmet medical needs in oncology. Management has prepared detailed budgets and cash flow forecasts for the years 2020 and 2021. These forecasts reflect the strategy of the Group and include significant expenses and cash outflows in relation to the development of selected research programs and product candidates. Based on its current scope of activities, the Group estimates that its treasury position as of December 31, 2019 is sufficient to cover its cash requirements until the first half 2021, which is beyond the readouts of our clinical trials currently ongoing. Capital management The Group’s objectives when managing capital are to safeguard the Group’s ability to continue as a going concern in order to provide returns for shareholders and benefits for other stakeholders and to maintain an adequate structure to limit to costs of capital.

Critical accounting estimates a

Critical accounting estimates and judgments	12 Months Ended
	Dec. 31, 2019
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Critical accounting estimates and judgments	NOTE 5: CRITICAL ACCOUNTING ESTIMATES AND JUDGMENTS The preparation of the Group’s financial statements requires management to make judgments, estimates and assumptions that affect the reported amounts of revenues, expenses, assets and liabilities, and the disclosure of contingent liabilities, at the end of the reporting period. Estimates and judgements are continually evaluated and are based on historical experience and other factors, including expectations of future events that are believed to be reasonable under the circumstances. Uncertainty about these assumptions and estimates could result in outcomes that require a material adjustment to the carrying amount of the asset or liability affected in future periods. In the process of applying the Group’s accounting policies, management has made judgments and has used estimates and assumptions concerning the future. The resulting accounting estimates will, by definition, seldom equal the related actual results. The estimates and assumptions that have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year are addressed below. Going Concern When assessing going concern, the Group’s Board of directors considers mainly the following factors: • the treasury available at balance sheet date; • the cash burn projected in accordance with approved budget for next 12-month • the availability of grant funding and outcome of ongoing and future grant applications payback loan to be received for the next 12-month Revenue The recognition of revenue relating to license and collaboration agreements involves management estimates and requires judgement as to: (i) classifying the license agreement (right-to-use right-to-access (ii) identifying the performance obligations comprised in the contract; (iii) estimating probability for (pre-)clinical (iv) determining the agreed variable considerations to be included in the transaction price taking into account the constraining limit of the “highly probable” criteria; (v) allocating the transaction price according to the stand-alone selling price of each of the performance obligations; and (vi) estimating the finance component in the transaction price, based on the contract expected duration and discount rate. The management makes its judgment taking into account all information available about clinical status of the underlying projects at the reporting date and the legal analysis of each applicable contracts. Further details are contained in Note 24. Recoverable Cash Advances received from the Walloon Region As explained in note 3, accounting for RCAs requires initial recognition of the fair value of the loan received to determine the benefit of the below-market rate of interest, which shall be measured as the difference between the initial carrying value of the loan and the proceeds received. Loans granted to entities in their early stages of operations, for which there is significant uncertainty about whether any income will ultimately be generated and for which any income which will be generated will not arise until a number of years in the future, normally have high interest rates. Judgment is required to determine a rate which may apply to a loan granted on an open market basis. In accordance with the RCA agreements, the following two components are assessed when calculating estimated future cash flows: • 30% of the initial RCA, which is repayable when the Group exploits the outcome of the research financed; and • a remaining amount, which is repayable based on a royalty percentage of future sales milestones. After initial recognition, RCA liabilities are measured at amortized cost using the cumulative catch up method requiring management to regularly revise its estimates of payments and to adjust the carrying amount of the financial liability to reflect actual and revised estimated cash flows. Measurement and impairment of non-financial With the exception of goodwill and certain intangible assets for which an annual impairment test is required, the Group is required to conduct impairment tests where there is an indication of impairment of an asset. Measuring the fair value of a non-financial Business combinations In respect of acquired businesses by the Group, significant judgement is made to determine whether these acquisitions are to be considered as an asset deal or as a business combination. Determining whether a particular set of assets and activities is a business should be based on whether the integrated set is capable of being conducted and managed as a business by a market participant. Moreover, managerial judgement is particularly involved in the recognition and fair value measurement of the acquired assets, liabilities, contingent liabilities and contingent consideration. In making this assessment management considers the underlying economic substance of the items concerned in addition to the contractual terms. Contingent consideration provisions The Group records a liability for the estimated fair value of contingent consideration arising from business combinations. The estimated amounts are the expected payments and timing of such payments, determined by considering the possible scenarios of forecast sales and other performance criteria, the amount to be paid under each scenario, and the probability of each scenario, which is then discounted to a net present value. The estimates could change substantially over time as new facts emerge and each scenario develops. Deferred Tax Assets Deferred tax assets for unused tax losses are recognized to the extent that it is probable that taxable profit will be available against which the losses can be utilized. Significant management judgment is required to determine the amount of deferred tax assets that can be recognized, based upon the likely timing and level of future taxable profits together with future tax planning strategies. Further details are contained in Note 30. Share-based payment transactions The Group measures the cost of equity-settled transactions with employees by reference to the fair value of the equity instruments at the date at which they are granted. Estimating fair value for share-based payment transactions requires determining the most appropriate valuation model, which is dependent on the terms and conditions of the grant. This estimate also requires determining the most appropriate inputs to the valuation model including the expected life of the share option, volatility and dividend yield and making assumptions about them. The assumptions and models used for estimating fair value for share-based payment transactions are disclosed in Note 16.

Operating segment information

Operating segment information	12 Months Ended
	Dec. 31, 2019
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Operating segment information	NOTE 6: OPERATING SEGMENT INFORMATION The chief operating decision-maker (CODM), who is responsible for making strategic decisions, allocating resources and assessing performance of the Group, has been identified as the Board of Directors. Since the acquisition of the oncological platform in 2015, the management and the CODM have determined that there are two operating segments, being: • the cardiology segment, regrouping the Cardiopoiesis platform, the Corquest Medical, Inc. (Corquest) platform and C-Cath ez • the immuno-oncology segment regrouping all assets developed based on the CAR-T Although the Group is currently active in Europe and in the US, no geographical financial information is currently available given the fact that the core operations are currently still in a study phase. No disaggregated information on product level or geographical level or any other level currently exists and hence also not considered by the Board of Directors for assessing performance or allocating resources. CODM is not reviewing assets by segments, hence no segment information per assets is disclosed. At reporting date, the main Group’s non-current €’000 For the year ended December 31, 2017 Cardiology Immuno-oncology Corporate Group Total Revenues 35 3,505 3,540 Cost of Sales (515 ) (515 ) Gross Profit 35 2,990 — 3,025 Research & Development expenses (2,881 ) (20,027 ) — (22,908 ) General & Administrative expenses — — (9,310 ) (9,310 ) Other Income and expenses 1,070 151 1,370 2,589 Non-recurring (1,932 ) — (24,341 ) (26,273 ) Operating Profit (Loss) (3,708 ) (16,886 ) (32,281 ) (52,876 ) Net Financial Charges — — (3,521 ) (3,518 ) Profit (Loss) before taxes (3,708 ) (16,886 ) (35,802 ) (56,396 ) Income Taxes — — 1 1 Profit (Loss) for the year 2017 (3,708 ) (16,886 ) (35,801 ) (56,395 ) In 2017, there were some important one-time non-recurrent non-recurrent €’000 For the year ended 31 December 2018, Cardiology Immuno-oncology Corporate Group Total Revenue recognized at a point in time 2,399 — — 2,399 Revenue recognized over time — 716 — 716 Total Revenue 2,399 716 — 3,115 Cost of Sales — — — — Gross Profit 2,399 716 — 3,115 Research & Development expenses (375 ) (23,202 ) — (23,577 ) General & Administrative expenses — — (10,387 ) (10,387 ) Net Other income/(loss) (686 ) (6,765 ) 130 (7,321 ) Operating Profit/(Loss) - EBIT 1,338 (29,251 ) (10,257 ) (38,170 ) Net financial income/(loss) — — 743 743 Profit/(Loss) before taxes 1,338 (29,251 ) (9,515 ) (37,428 ) Income Taxes — — 0 0 Profit/(Loss) for the year 2018 1,338 (29,251 ) (9,514 ) (37,427 ) In 2018, the Group entered into a license agreement with Mesoblast relating to the C-Cath ez €’000 For the year ended 31 December 2019, Cardiology Immuno-oncology Corporate Group Total Revenue recognized at a point in time 6 — — 6 Revenue recognized over time — — — — Total Revenue 6 — — 6 Cost of Sales — — — — Gross Profit 6 — — 6 Research & Development expenses (146 ) (25,049 ) — (25,196 ) General & Administrative expenses — — (9,070 ) (9,070 ) Net Other income/(loss) 63 5,228 90 5,381 Operating Profit/(Loss) - EBIT (78 ) (19,821 ) (8,979 ) (28,879 ) Net financial income/(loss) 212 (183 ) 211 239 Profit/(Loss) before taxes 134 (20,005 ) (8,769 ) (28,640 ) Income Taxes — — 8 8 Profit/(Loss) for the year 2019 134 (20,005 ) (8,761 ) (28,632 ) Since mid of 2016, the Group is fully focused on the development of its immuno-oncology platform. Therefore, as of December 31, 2019, most of the R&D expenses were incurred in the immuno-oncology segment, in line with prior year.

Intangible assets

Intangible assets	12 Months Ended
	Dec. 31, 2019
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Intangible assets	NOTE 7: INTANGIBLE ASSETS The change in intangible assets is broken down as follows, per class of assets: (€’000) Goodwill In-process Development Patents, Software Total Cost: At 1 January 2018 914 34,854 1,084 13,337 111 50,300 Additions — — — 877 55 932 Currency translation adjustments (31 ) (1,177 ) — — — (1,208 ) Divestiture — — — — (2 ) (2 ) At 31 December 2018 883 33,677 1,084 14,214 164 50,022 Additions — — — 181 46 227 Currency translation adjustments — — — — — — Divestiture — — — (1,493 ) (30 ) (1,523 ) At 31 December 2019 883 33,678 1,084 12,903 179 48,726 Accumulated amortization At 1 January 2018 — — (345 ) (13,337 ) (110 ) (13,792 ) Amortization charge — — (66 ) (1 ) (0 ) (68 ) Divestiture — — — — 2 2 At 31 December 2018 — — (411 ) (13,338 ) (109 ) (13,858 ) Amortization charge — — (66 ) (92 ) (12 ) (169 ) Divestiture — — — 1,493 8 1,501 Impairment (non-recurring — — — — — — At 31 December 2019 — — (477 ) (11,938 ) (112 ) (12,527 ) Net book value Cost 883 33,677 1,084 14,214 164 50,022 Accumulated amortization — — (411 ) (13,338 ) (109 ) (13,858 ) At 31 December 2018 883 33,677 673 876 55 36,164 Cost 883 33,678 1,084 12,903 179 48,726 Accumulated amortization — — (477 ) (11,938 ) (112 ) (12,527 ) At 31 December 2019 883 33,678 607 965 66 36,199 The capitalized development costs relate to the development of C-Cath ez ez ez C-Cure, CYAD-01, CYAD-02, CYAD-101…) Goodwill, In-process • Goodwill and In-process In-Process • A license, granted in August 2007 by Mayo Clinic (for an amount of €9.5 million) upon the Group’s inception and an extension to the licensed field of use, granted on October 29, 2010 for a total amount of €2.3 million. The license and its extension were amortized straight line over a period of 20 years, in accordance with the license term. A €6.0 million impairment loss has been recognized on the remaining net book value in the year ended 31 December 2017. • Patents acquired upon the acquisition of CorQuest LLC in November 2014. The fair value of these intellectual rights was then determined to be €1.5 million. These patents were amortized over 18 years, corresponding to the remaining intellectual property protection filed for the first patent application in 2012. A €1.2 million impairment loss has been recognized on the remaining net book value in the year ended 31 December 2017. On November 22, 2019 the Heart-XS • Exclusive Agreement for Horizon Discovery’s shRNA Platform to develop next-generation allogenic CAR-T CYAD-02. The Immuno-oncology cash generating unit (CGU) reach a net book value of €35.5 million at balance sheet date. This CGU is composed by: • the goodwill and In-process • the Horizon Discovery’s shRNA platform. The variance on the total intangible assets as of December 31, 2019 resulted primarily from the regular amortization of C-Cath ez Impairment testing Impairment testing is detailed below. Immuno-oncology CGU impairment test 4 Goodwill and In-process 11-year CYAD-01 CYAD-101 CYAD-01 CYAD-101. Management’s key assumptions about projected cash flows when determining fair value less costs to sell are as follows: •  Discount rate (WACC) 14.6% (13,9% in 2018), in line with industry standards for biotechnological companies and WACC used by Equity Research companies following the Group 4 The uncertainly raised by the COVID-19 •  Sales revenue growth in the Terminal Value a decline of 25% of the estimated product revenue has been considered in the Terminal Value (for infinite extrapolation purposes) •  Probabilities of Success (PoS) based on Clinical Development Success Rates observed for the period 2006-2015 determined by independent business intelligence consulting companies for hematologic and solid oncological diseases. Probability of the Group’s product candidates getting on the market used were in line with prior year and as follows: PoS Phase I Phase I to II Phase II to Phase III to BLA to Cumulative CYAD-01 CYAD-101 100 % 63 % 26 % 45 % 83 % 6.3 % The sensitivity analyses are based on a change in an assumption while holding all other assumptions constant. The following table presents the sensitivity analyses of the recoverable amount of the CGU associated to the immuno-oncology operations: Sensitivity analysis Discount rate (WACC) Terminal Revenue Growth rate Impact on model 14.6% 15.3% 16.0% -35% -12% -20% -27% -30% -7% -15% -23% -25% Model -9% -17% Even at the lower terminal revenue growth and higher discount rate, the recoverable value of the CGU exceeds its carrying amount at balance sheet date. C-Cure Pursuant to 2017 strategic decision to focus all the efforts of the Group on the development of the immuno-oncology platform and the lack of strategic business development opportunities identified for the C-Cure year-end,

Property, plant and equipment

Property, plant and equipment	12 Months Ended
	Dec. 31, 2019
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Property, plant and equipment	NOTE 8: PROPERTY, PLANT AND EQUIPMENT (€’000) Property Equipment Furnitures Leasehold Total Cost: At 1 January 2018 — 4,537 445 3,059 8,042 Additions — 564 10 260 833 Reclass BMS SA — (1,032 ) 24 1,007 — Disposals — (123 ) (154 ) (140 ) (417 ) Currency translation adjustments — 1 4 8 13 At 31 December 2018 — 3,947 329 4,195 8,470 Additions 2,810 648 37 167 3,662 Disposals — (496 ) (59 ) (172 ) (728 ) Currency translation adjustments — 0 — 4 4 At 31 December 2019 2,810 4,099 307 4,193 11,409 Accumulated depreciation: At 1 January 2018 — (3,126 ) (229 ) (1,395 ) (4,750 ) Reclass BMS SA — 786 (24 ) (761 ) — Depreciation charge — (529 ) (49 ) (469 ) (1,048 ) Currency translation adjustments — 117 93 133 343 Disposals — 0 (1 ) (1 ) (1 ) At 31 December 2018 — (2,751 ) (211 ) (2,494 ) (5,456 ) Depreciation charge (399 ) (711 ) (54 ) (455 ) (1,619 ) Disposals — 496 59 172 728 Currency translation adjustments — (0 ) — (1 ) (1 ) At 31 December 2019 (399 ) (2,967 ) (205 ) (2,776 ) (6,347 ) Net book value Cost — 3,947 329 4,195 8,471 Accumulated depreciation — (2,751 ) (211 ) (2,494 ) (5,456 ) At 31 December 2018 — 1,196 117 1,701 3,014 Cost 2,810 4,099 307 4,193 11,409 Accumulated depreciation (399 ) (2,967 ) (205 ) (2,776 ) (6,347 ) At 31 December 2019 2,411 1,132 101 1,417 5,061 Property, Plant and Equipment is mainly composed of right-of-use The variance on the total tangible assets as of December 31, 2019 resulted primarily from the capitalization of leases as a right-of-use Leases Some lease relates to contracts with financial institutions and relate to laboratory and office equipment. All such leases have a maturity of three years. A key common feature is that they include a bargain option to purchase the leased asset at the end of the three-year-lease term. The total of future minimum lease payments at the end of the reporting period, and their present value reported on the balance sheet, are similar amounts. The acquisition of BMS in 2016 was accounted for as an asset deal. The fair value of the assets acquired is concentrated in one identifiable asset, i.e. the GMP laboratories. A reclass of BMS equipment to Leasehold has been operated in 2018 without having any impact on the net book value. The difference between the purchase price and the net assets of BMS at the date of acquisition is then allocated entirely to the Property, Plant and Equipment.

Other non-current assets

Other non-current assets	12 Months Ended
	Dec. 31, 2019
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Other non-current assets	NOTE 9: OTHER NON-CURRENT (€’000) As at 31 December, 2019 2018 Non-current 1,955 1,743 Net investment in Lease 477 — Total Non-current 2,432 1,743 In May 2018, the Group has entered into an exclusive license agreement with Mesoblast. More details on the transaction and its revenue recognition pattern is set forth in disclosure note 24. At balance sheet date, a net investment in lease has been recorded in view of adoption of new accounting standard IFRS16 Leases (€’000) As at 31 December, 2019 2018 R&D Tax credit receivable 3,051 1,472 Total Non-current Grant receivables 3,051 1,472 Deposits 257 215 Total Other non-current 257 215 In 2017, the Group recognized for the first time a R&D tax credit (€1.2 million) receivable from the federal government that included a one-off catch-up The non-current

Inventories and Work in Progres

Inventories and Work in Progress	12 Months Ended
	Dec. 31, 2019
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Inventories and Work in Progress	NOTE 10: INVENTORIES AND WORK IN PROGRESS Not applicable

Trade, Other Receivables and Ot

Trade, Other Receivables and Other current assets	12 Months Ended
	Dec. 31, 2019
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Trade, Other Receivables and Other current assets	NOTE 11: TRADE, OTHER RECEIVABLES AND OTHER CURRENT ASSETS (€’000) As at 31 December, 2019 2018 Trade receivables 156 277 Advance deposits 149 90 Net Investment in Lease 253 — Other receivables — — Total Trade and Other receivables 558 367 Current Grant receivables (RCAs) 693 — Current Grant receivables (Others) 993 — Total Current Grant receivables 1,686 — Prepaid expenses 647 593 VAT receivable 356 255 Income and other tax receivables 251 737 Total Other current assets 1,253 1,585 Total Trade receivables, advances and other current assets 3,497 1,952 Impairment of receivables is assessed on an individual basis at the end of each accounting year. At balance sheet date, no receivable was overdue. There were no carrying amounts for trade and other receivables denominated in foreign currencies, except for the net investment in lease for which carrying amount is under USD. No impairments were recorded on trade receivables and other current assets. Trade receivables balance increase mainly due to net investment in lease for some subleased office space after first adoption of IFRS 16 Leases The advance deposits increase relates to the clinical trials on CYAD-02 non-clinical year-end As of December 31, 2019, grant receivables for a total amount of €1.7 million has been recorded due to new Walloon Region conventions signed end of 2019 (CYAD-01 CYAD-221 CYAD-221 CYAD-03 In comparison with year-end

Short Term Investments

Short Term Investments	12 Months Ended
	Dec. 31, 2019
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Short Term Investments	NOTE 12: SHORT-TERM INVESTMENT (€’000) As at 31 December, 2019 2018 Short-term cash deposits — 8,559 Investment in equity securities 0 639 Total 0 9,197 Amounts recorded as short-term investments correspond to short-term cash deposits with fixed interest rates. Short-term deposits are made for variable periods (from 1 to 12 months) depending on the short-term cash requirements of the Group. Interest is calculated at the respective short-term deposit rates. Given the level of market interest rates of corporate deposits of short-term maturities, the Group has reduced the amounts invested in short-term deposits over 2019. Mesoblast equity shares received in settlement of the upfront payment for the C-Cath ez

Cash and Cash Equivalents

Cash and Cash Equivalents	12 Months Ended
	Dec. 31, 2019
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Cash and Cash Equivalents	NOTE 13: CASH AND CASH EQUIVALENT (€‘000) As at 31 December, 2019 2018 Cash at bank and on hand 39,338 40,542 Total 39,338 40,542 Cash at banks earn interest at floating rates based on daily bank deposit rates. The credit quality of cash and cash equivalents and short-term cash deposit balances may be categorized between A-1

Investment in Subsidiaries

Investment in Subsidiaries	12 Months Ended
	Dec. 31, 2019
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Investment in Subsidiaries	NOTE 14: INVESTMENT IN SUBSIDIARIES The consolidation scope of the Group is as follows, for both current and comparative years presented in these year-end Name Country of Nature of Business Proportion of shares directly Proportion of Proportion of non-controlling Celyad SA BE Biopharma Parent company Celyad Inc US Biopharma 100% 100 % 0 % CorQuest Medical Inc US Medical Device 100% 100 % 0 % Biological Manufacturing Services SA BE Manufacturing 100% 100 % 0 % Cardio3 Inc was incorporated in 2011 to support clinical and regulatory activities of the Group in the US. Cardio3 Inc was renamed in Celyad Inc in 2015. The growth of the activities of Celyad Inc is associated to the development of the US clinical and regulatory activities of the Group in the US. CorQuest Medical Inc has been acquired on November 5, 2014. CorQuest Medical Inc. is developing Heart-XS, Heart-XS Biological Manufacturing Services SA (BMS) has been acquired in May 2016. BMS owns GMP laboratories. BMS rent its laboratories to Celyad SA since 2009 and until April 30, 2016. Until the acquisition, BMS had been treated as a related party to the Group. Oncyte LLC had been acquired on January 21, 2015. It has been liquidated in March 2018. Oncyte LLC was the company hosting the CAR T-Cell pre-clinical

Share Capital

Share Capital	12 Months Ended
	Dec. 31, 2019
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Share Capital	NOTE 15: SHARE CAPITAL The number of shares issued is expressed in units As of 31 December, 2019 2018 Total number of issued and outstanding shares 13,942,344 11,942,344 Total share capital (€‘000) 48,513 41,553 As of December 31, 2019, the share capital amounts to €48,513k represented by 13,942,344 fully authorized and subscribed and paid-up non-employees History of the capital of the Company The Company has been incorporated on July 24, 2007 with a share capital of €62,500 by the issuance of 409,375 class A shares. On August 31, 2007, the Company has issued 261,732 class A shares to Mayo Clinic by way of a contribution in kind of the upfront fee that was due upon execution of the Mayo License for a total amount of €9,500,000. Round B Investors have participated in a capital increase of the Company by way of a contribution in kind of a convertible loan (€2,387,049) and a contribution in cash (€4,849,624 of which €1,949,624 uncalled) on December 23, 2008; 204,652 class B shares have been issued at the occasion of that capital increase. Since then, the capital is divided in 875,759 shares, of which 671,107 are class A shares and 204,652 are class B shares. On October 29, 2010, the Company closed its third financing round resulting in a capital increase totaling €12,100,809. The capital increase can be detailed as follows: • capital increase in cash by certain existing investors for a total amount of €2,609,320.48 by the issuance of 73,793 class B shares at a price of €35.36 per share; • capital increase in cash by certain existing investors for a total amount of €471,240 by the issuance of 21,000 class B shares at a price of €22.44 per share; • capital increase in cash by certain new investors for a total amount of €399,921.60 by the issuance of 9,048 class B shares at a price of €44.20 per share; • exercise of 12,300 warrants (“Warrants A”) granted to the Round C investors with total proceeds of €276,012 and issuance of 12,300 class B shares. The exercise price was €22.44 per Warrant A; • contribution in kind by means of conversion of the loan C for a total amount of €3,255,524.48 (accrued interest included) by the issuance of 92,068 class B shares at a conversion price of €35.36 per share; • contribution in kind by means of conversion of the loan D for a total amount of €2,018,879.20 (accrued interest included) by the issuance of 57,095 class B shares at a conversion price of €35.36 per share. The loan D is a convertible loan granted by certain investors to the Company on 14 October 2010 for a nominal amount of €2,010,000. • contribution in kind of a payable towards Mayo Foundation for Medical Education and Research for a total amount of €3,069,911 by the issuance of 69,455 class B shares at a price of €44.20 per share. The payable towards Mayo Clinic was related to (i) research undertaken by Mayo Clinic in the years 2009 and 2010, (ii) delivery of certain materials, (iii) expansion of the Mayo Clinical Technology License Contract by way the Second Amendment dated October 18, 2010. On May 5, 2011, pursuant the decision of the Extraordinary General Meeting, the capital was reduced by an amount of €18,925,474 equivalent to the outstanding net loss as of 31 December 2010. On May 31, 2013, the Company closed its fourth financing round, the ‘Round D financing’. The convertible loans E, F, G and H previously recorded as financial debt were converted in shares which led to an increase in equity for a total amount of €28,645k of which € 5,026k is accounted for as capital and € 6,988k as share premium. The remainder (€ 16,613k) is accounted for as other reserves. Furthermore, a contribution in cash by existing shareholders of the Company led to an increase in share capital and issue premium by an amount of €7,000k. At the Extraordinary Shareholders Meeting of June 11, 2013 all existing classes of shares of the Company have been converted into ordinary shares. Preferred shares have been converted at a 1 for 1 ratio. On July 5, 2013, the Company completed its Initial Public Offering. The Company issued 1,381,500 new shares at €16.65 per shares, corresponding to a total of €23,002k. On July 15, 2013, the over-allotment option was fully exercised for a total amount of €3,450k corresponding to 207,225 new shares. The total IPO proceeds amounted to €26,452k and the capital and the share premium of the Company increased accordingly. The costs relating to the capital increases performed in 2013 amounted to €2.8 million and are presented as a deduction of share premium. On June 11, 2013, the Extraordinary General Shareholders’ Meeting of Celyad SA authorized the Board of Directors to increase the share capital of the Company, in one or several times, and under certain conditions set forth in extenso in the articles of association. This authorization is valid for a period of five years starting on July 26, 2013 and until July 26, 2018. The Board of Directors may increase the share capital of the Company within the framework of the authorized capital for an amount of up to €21,413k. Over the course of 2014, the capital of the Company was increased in June 2014 by way of a capital increase of €25,000k represented by 568,180 new shares fully subscribed by Medisun International Limited. In 2014, the capital of the Company was also increased by way of exercise of Company warrants. Over four different exercise periods, 139,415 warrants were exercised resulting in the issuance of 139,415 new shares. The capital and the share premium of the Company were therefore increased respectively by €488k and €500k. In January 2015, the shares of OnCyte, LLC were contributed to the capital of the Company, resulting in a capital increase of €3,452k and the issuance of 93,087 new shares. In 2015, the Company conducted two fund raisings. A private placement was closed in March resulting in a capital increase of €31,745k represented by 713,380 new shares. The Company also completed an IPO on Nasdaq in June, resulting in a capital increase of €87,965k represented by 1,460,000 new shares. Also, in 2015, the capital of the Company was also increased by way of exercise of Company warrants. Over three different exercise periods, 6,749 warrants were exercised resulting in the issuance of 6,749 new shares. The capital and the share premium of the Company were therefore increased respectively by €23k and €196k. Over 2017 the capital of the Company was also increased by way of exercise of Company warrants. Over four different exercise periods, 225,966 warrants were exercised resulting in the issuance of 225,966 new shares. The capital of the Company was therefore increased by €625k. In August 2017, pursuant to the amendment of the agreements with Celdara Medical LLC and Dartmouth College, the CAR-T In May 2018 the Company completed a global offering of $54.4 million (€46.1 million), resulting in cash proceeds for an amount of €43.0 million net of bank fees and transaction costs. In May 2019, share premium decreased as a result of the absorption of accounting losses for an amount of €172.3 million, with a counterpart in the financial statements line item ‘Accumulated Deficit’. The absorption of the accumulated deficit into share premium is a non-cash In September 2019, the Company completed a global offering of $20.0 million (€18.2 million), resulting in cash proceeds for an amount of €16.4 million net of bank fees and transaction costs. As of December 31, 2019, all shares issued have been fully paid. The following share issuances occurred since the incorporation of the Company: Category Transaction date Description # of shares Par value Class A shares 24 July 2007 Company incorporation 409,375 0.15 Class A shares 31 August 2007 Contribution in kind (upfront fee Mayo License) 261,732 36.30 Class B shares 23 December 2008 Capital increase (Round B) 137,150 35.36 Class B shares 23 December 2008 Contribution in kind (Loan B) 67,502 35.36 Class B shares 28 October 2010 Contribution in cash 21,000 22.44 Class B shares 28 October 2010 Contribution in kind (Loan C) 92,068 35.36 Class B shares 28 October 2010 Contribution in kind (Loan D) 57,095 35.36 Class B shares 28 October 2010 Contribution in cash 73,793 35.36 Class B shares 28 October 2010 Exercise of warrants 12,300 22.44 Class B shares 28 October 2010 Contribution in kind (Mayo receivable) 69,455 44.20 Class B shares 28 October 2010 Contribution in cash 9,048 44.20 Class B shares 31 May 2013 Contribution in kind (Loan E) 118,365 38.39 Class B shares 31 May 2013 Contribution in kind (Loan F) 56,936 38.39 Class B shares 31 May 2013 Contribution in kind (Loan G) 654,301 4.52 Class B shares 31 May 2013 Contribution in kind (Loan H) 75,755 30.71 Class B shares 31 May 2013 Contribution in cash 219,016 31.96 Class B shares 4 June 2013 Conversion of warrants 2,409,176 0.01 Ordinary shares 11 June 2013 Conversion of Class A and Class B shares in ordinary shares 4,744,067 — Ordinary shares 5 July 2013 Initial Public Offering 1,381,500 16.65 Ordinary shares 15 July 2013 Exercise of over-allotment option 207,225 16.65 Ordinary shares 31 January 2014 Exercise of warrants issued in September 2008 5,966 22.44 Ordinary shares 31 January 2014 Exercise of warrants issued in May 2010 333 22.44 Ordinary shares 31 January 2014 Exercise of warrants issued in January 2013 120,000 4.52 Ordinary shares 30 April 2014 Exercise of warrants issued in September 2008 2,366 22.44 Ordinary shares 16 June 2014 Capital increase 284,090 44.00 Ordinary shares 30 June 2014 Capital increase 284,090 44.00 Ordinary shares 4 August 2014 Exercise of warrants issued in September 2008 5,000 22.44 Ordinary shares 4 August 2014 Exercise of warrants issued in October 2010 750 35.36 Ordinary shares 3 November 2014 Exercise of warrants issued in September 2008 5,000 22.44 Ordinary shares 21 January 2015 Contribution in kind (Celdara Medical LLC) 93,087 37.08 Ordinary shares 7 February 2015 Exercise of warrant issued in May 2010 333 22.44 Ordinary shares 3 March 2015 Capital increase 713,380 44.50 Ordinary shares 11 May 2015 Exercise of warrant issued in May 2010 500 22.44 Ordinary shares 24 June 2015 Capital increase 1,460,000 60.25 Ordinary shares 4 August 2015 Exercise of warrant issued in May 2010 666 22.44 Ordinary shares 4 August 2015 Exercise of warrant issued in October 2010 5,250 35.36 Ordinary shares 1 February 2017 Exercise of warrant issued in May 2013 207,250 2.64 Ordinary shares 2 May 2017 Exercise of warrant issued in May 2013 4,900 2.64 Ordinary shares 1 August 2017 Exercise of warrant issued in May 2013 7,950 2.64 Ordinary shares 23 August 2017 Contribution in kind (Celdara Medical LLC) 328,275 32.35 Ordinary shares 9 November 2017 Exercise of warrant issued in May 2013 5,000 2.64 Ordinary shares 9 November 2017 Exercise of warrant issued in October 2010 866 35.36 Ordinary shares 7 February 2018 Exercise of warrant issued in May 2013 4,500 2.64 Ordinary shares 22 May 2018 Capital increase 2,070,000 22.29 Ordinary shares 16 Sept 2019 Capital increase 2,000,000 9.08 (€000) Nature of the transactions Share Share Number of shares Balance as of January 1st, 2018 34,337 170,297 9,867,844 Issue of shares related to exercise of warrants 12 — 4,500 Capital increase as a result of the global offering 7,204 35,796 2,070,000 Share Based Payment — 56 — Balance as of December 31, 2018 41,553 206,149 11,942,344 Issue of shares related to exercise of warrants — — — Absorption of accounting losses into Share premium — (172,287 ) — Capital increase as a result of the global offering 6,960 9,488 2,000,000 Share Based Payment — — — Balance as of December 31, 2019 48,513 43,349 13,942,344 The total number of shares issued and outstanding as of December 31, 2019 totals 13,942,344 ordinary common shares.

Share-Based Payments

Share-Based Payments	12 Months Ended
	Dec. 31, 2019
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Share-Based Payments	NOTE 16: SHARE-BASED PAYMENTS The Group operates an equity-based compensation plan, whereby warrants are granted to directors, management and selected employees and non-employees. Each warrant gives the beneficiaries the right to subscribe to one common share of the Group. The warrants are granted for free and have an exercise price equal to the lower of the average closing price of the Group share over the 30 days prior to the offer, and the last closing price before the day of the offer, as determined by the Board of Directors of the Group. Changes in the number of warrants outstanding and their related weighted average exercise prices are as follows: 2019 2018 Weighted average Number of warrants Weighted average Number of warrants Outstanding as of 1 January 30.71 731,229 31.76 674,962 Granted 13.21 610,250 23.09 111,600 Forfeited 8.24 (24,100 ) 28.79 (50,833 ) Exercised — 0 2.64 (4,500 ) Expired 23.60 (24,999 ) — 0 At 31 December 22.56 1,292,380 30.71 731,229 No warrant exercised in 2019. There were 24,999 warrants expired in 2019, that were issued in May 2014. Warrants outstanding at the end of the year have the following expiry date and exercise price: Warrant plan issuance Vesting date Expiry date Number of warrants Number of warrants Exercise price 29 October 2010 29 October 2013 29 October 2020 766 766 35.36 06 May 2013 06 May 2016 06 May 2023 2,500 2,500 2.64 05 May 2014 05 May 2017 05 May 2024 35,698 60,697 38.29 05 November 2015 05 November 2018 05 November 2025 250,982 245,982 33.39 08 December 2016 08 December 2019 08 December 2021 42,500 42,500 22.41 29 June 2017 29 June 2020 29 June 2022 285,084 294,484 31.44 26 October 2018 26 October 2021 19 September 2024 401,350 84,300 18.07 25 October 2019 25 October 2022 25 October 2024 273,500 — 8.16 1,292,380 731,229 Warrants issued on October 29, 2010 At the Extraordinary Shareholders Meeting of October 29, 2010, a plan of 79,500 warrants was approved. Warrants were offered to Group’s employees, non-employees The 61,050 warrants were vested in equal tranches over a period of three years. The warrants become 100% vested after the third anniversary the issuance. The warrants that are vested can only be exercised at the end of the third calendar year following the issuance date, thus starting on January 1, 2014. The exercise price amounts to €35.36. Warrants not exercised within 10 years after issue become null and void. Warrants issued on May 6, 2013 At the Extraordinary Shareholders Meeting of 6 May 2013, a plan of 266,241 warrants was approved. Warrants were offered to Group’s employees and management team. Out of the 266,241 warrants offered, 253,150 warrants were accepted by the beneficiaries and 2,500 warrants are outstanding on the date hereof. The 253,150 warrants were vested in equal tranches over a period of three years. The warrants become 100% vested after the third anniversary the issuance. The warrants that are vested can only be exercised at the end of the third calendar year following the issuance date, thus starting on January 1, 2017. The exercise price amounts to €2.64. Warrants not exercised within 10 years after issue become null and void. Warrants issued on May 5, 2014 At the Extraordinary Shareholders Meeting of 5 May 2014, a plan of 100,000 warrants was approved. Warrants were offered to Group’s employees, non-employees The 100,000 warrants were vested in equal tranches over a period of three years. The warrants become 100% vested after the third anniversary the issuance. The warrants that are vested can only be exercised at the end of the third calendar year following the issuance date, thus starting on January 1, 2018. The exercise price of the different tranches ranges from €33.49 to €45.05. Warrants not exercised within 10 years after issue become null and void. Warrants issued on November 5, 2015 At the Extraordinary Shareholders Meeting of November 5, 2015, a plan of 466,000 warrants was approved. Warrants were offered to Group’s employees, non-employees These warrants vest in equal tranches over a period of three years. The warrants become 100% vested after the third anniversary of issuance. The warrants that are vested can only be exercised as from the end of the third calendar year following the issuance date, thus starting on January 1, 2019. The exercise price of the different tranches ranges from €15.90 to €34.65. Warrants not exercised within 10 years after issue become null and void. Warrants issued on December 8, 2016 On December 8, 2016, the Board of Directors issued a new plan of 100,000 warrants. An equivalent number of warrants were cancelled from the remaining pool of warrants of the plan of November 5, 2015. Warrants were offered to Group’s employees and non-employees These warrants will vest in equal tranches over a period of three years. The warrants become 100% vested after the third anniversary of issuance. The warrants that are vested can only be exercised as from the end of the third calendar year following the issuance date, thus starting on January 1, 2020. The exercise price of the different tranches ranges from €17.60 to €36.81. Warrants not exercised within 5 years after issue become null and void. Warrants issued on June 29, 2017 At the Extraordinary Shareholders Meeting of June 29, 2017, a plan of 520,000 warrants was approved. Warrants were offered in different tranches to beneficiaries (employees, non-employees These warrants will be vested in equal tranches over a period of three years. The warrants become 100% vested after the third anniversary of issuance. The warrants that are vested can only be exercised as from the end of the third calendar year following the issuance date, thus starting on January 1, 2021. The exercise price of the different tranches ranges from €31.34 to €48.89. Warrants not exercised within 5 years after issue become null and void. Warrants issued on October 26, 2018 On October 26, 2018, the Board of Directors issued a new plan of 700,000 warrants. Warrants were offered in different tranches to beneficiaries (employees, non-employees These warrants will vest in equal tranches over a period of three years. The warrants become 100% vested after the third anniversary of issuance. The warrants that are vested can only be exercised as from the end of the third calendar year following the issuance date, thus starting on January 1, 2022. The exercise price of the different tranches ranges from €9.36 to €22.04. Warrants not exercised within 5 years after issue become null and void. Warrants issued on October 25, 2019 On October 25, 2019, the Board of Directors issued a new plan of 939,500 warrants. Warrants were offered in different tranches to beneficiaries (employees, non-employees These warrants will vest in equal tranches over a period of three years. The warrants become 100% vested after the third anniversary of issuance. The warrants that are vested can only be exercised as from the end of the third calendar year following the issuance date, thus starting on January 1, 2023. The exercise price of the first offer was of €8.16 . Warrants not exercised within 5 years after issue become null and void. As a result, at December 31, 2019, there are 1,292,380 Warrants outstanding which represent approximately 8.48% of the total number of all issued and outstanding voting financial instruments. The fair value of the warrants has been determined at grant date based on the Black-Scholes formula. The variables, used in this model, are: Warrants issued on 29 October 31 January 06 May 05 May 05 Nov. 08 Dec. 29 June 26 October 25 October Total Number of warrants issued 79,500 140,000 266,241 100,000 466,000 100,000 520,000 700,000 939,500 3,311,241 Number of warrants granted 61,050 140,000 253,150 94,400 353,550 45,000 334,400 426,050 273,500 1,981,100 Number of warrants not fully vested as of 31 December 2019 — — — — — 12,500 285,084 401,350 273,500 972,434 Average exercise price (in €) 35.36 4.52 2.64 38.29 33.39 22.41 31.44 18.07 8.16 22.58 Expected share value volatility 35.60 % 35.60 % 39.55 % 67.73 % 60.53 % 61.03 % 60.61 % 58.82 % 59.14 % Risk-free interest rate 3.21 % 2.30 % 2.06 % 1.09 % 0.26 % (0.40 %) (0.23 %) (0.06 %) (0.38 %) Average fair value (in €) 9.00 2.22 12.44 25.22 21.73 11.28 15.65 8.80 3.97 12.34 Weighted average remaining contractual life 0.82 3.08 3.34 4.34 5.84 1.94 2.49 3.82 4.82 The total net expense recognized in the income statement for the outstanding warrants totals €2.8 million for the year 2019 (€3.6 million for the prior year 2018).

Post-Employment Benefits

Post-Employment Benefits	12 Months Ended
	Dec. 31, 2019
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Post-Employment Benefits	NOTE 17: POST-EMPLOYMENT BENEFITS (€’000) As at 31 December, 2019 2018 Pension obligations 398 131 Total 398 131 The Group operates a pension plan which requires contributions to be made by the Group to an insurance company. The pension plan is a defined contribution plan. However, because of the Belgian legislation applicable to 2nd pillar pension plans (so-called At the end of each year, the Group is measuring and accounting for the potential impact of defined benefit accounting for these pension plans with a minimum fixed guaranteed return. The contributions to the plan are determined as a percentage of the yearly salary. There are no employee contributions. The benefit also includes a death in service benefit. The amounts recognized in the balance sheet are determined as follows: As at 31 December, (€‘000) 2019 2018 Present value of funded obligations 2,330 1,838 Fair value of plan assets (1,932 ) (1,706 ) Deficit of funded plans 398 131 Total deficit of defined benefit pension plans 398 131 Liability in the balance sheet 398 131 The change in the defined benefit liability over the year is as follows: (€‘000) Present value of Fair value of plan Total As at 1 January 2018 1,704 1,499 204 Current service cost 190 0 190 Interest expense/(income) 36 31 5 1,929 1,530 399 Remeasurements - Return on plan assets, excluding amounts included in interest expense/(income) — 9 (9 ) - Actuarial (Gain)/loss due to change in actuarial assumptions (58 ) 0 (58 ) - Actuarial (Gain)/Loss due to experience (3 ) 0 (3 ) (61 ) 9 (70 ) Employer contributions: 0 198 (198 ) Benefits Paid (31 ) (31 ) — At 31 December 2018 1,838 1,707 131 As at 1 January 2019 1,838 1,707 131 Current service cost 193 0 193 Interest expense/(income) 44 31 13 2,076 1,737 339 Remeasurements - Return on plan assets, excluding amounts included in interest expense/(income) — 0 — - Actuarial (Gain)/loss due to change in actuarial assumptions 222 0 222 - Actuarial (Gain)/Loss due to experience 70 0 70 292 — 292 Employer contributions: 0 233 (233 ) Benefits Paid (38 ) (38 ) — At 31 December 2019 2,330 1,932 398 The income statement charge included in operating profit for post-employment benefits amount to: (€‘000) 2019 2018 Current service cost 193 190 Interest expense on DBO 44 36 Expected return on plan assets (40 ) (30 ) Net periodic pension cost 198 195 The re-measurements (€‘000) 2019 2018 Effect of changes in actuarial assumptions 222 (58 ) Effect of experience adjustments 70 (3 ) (Gain)/Loss on assets for the year 8 (9 ) Remeasurement of post-employment benefit obligations 301 (70 ) Plan assets relate all to qualifying insurance policies. The significant actuarial assumptions as per December 31, 2019 were as follows: Demographic assumptions (for both current and comparative years presented in these year-end • Mortality tables: mortality rates-5 • Withdrawal rate: 15% each year • Retirement age: 65 years Economic assumptions: • Yearly inflation rate: 1.8% • Yearly salary raise: 1.5% (above inflation) • Yearly discount rate: 1.2% If the discount rate would decrease with 0,5% then, the defined benefit obligation would increase with 6.2%. Reversely if the discount rate would increase with 0,5% then the defined benefit obligation would decrease with 6.6%. The above sensitivity analysis is based on a change in an assumption while holding all other assumptions constant. In practice, this is unlikely to occur, and changes in some of the assumptions may be correlated. When calculating the sensitivity of the defined benefit obligation to significant actuarial assumptions the same method (present value of the defined benefit obligation calculated with the projected unit credit method at the end of the reporting period) has been applied as when calculating the pension liability recognized within the statement of financial position. Through its defined benefit pension plan, the Group is exposed to several risks, the most significant of which are detailed below: • Changes in discount rate: a decrease in discount rate will increase plan liabilities; • Inflation risk: the pension obligations are linked to inflation, and higher inflation will lead to higher liabilities. The majority of the plan’s assets are either unaffected by or loosely correlated with inflation, meaning that an increase in inflation will also increase the deficit. The investment positions are managed by the insurance company within an asset-liability matching framework that has been developed to achieve long-term investments that are in line with the obligations under the pension schemes. Expected contributions to pension plans for next financial year amount to €0.2 million.

Other Reserves

Other Reserves	12 Months Ended
	Dec. 31, 2019
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Other Reserves	NOTE 18: OTHER RESERVES (€’000 ) Share based Convertible Currency Total Balance as at 1st January 2018 6,707 16,631 (17 ) 23,322 Vested share-based payments 3,539 0 0 3,539 Currency Translation differences subsidiaries 0 0 (1,194 ) (1,194 ) Balance as at 31 December 2018 10,246 16,631 (1,211 ) 25,667 Vested share-based payments 2,775 0 0 2,775 Currency Translation differences subsidiaries 0 0 (261 ) (261 ) Balance as at 31 December 2019 13,021 16,631 (1,472 ) 28,181

Advances Repayable

Advances Repayable	12 Months Ended
	Dec. 31, 2019
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Advances Repayable	NOTE 19: ADVANCES REPAYABLE As at December 31, (€‘000) 2019 2018 Non-Current 2,864 1,544 Non-Current 4,139 2,864 Current portion as at 1st January 276 226 Current portion as at 31 December 346 276 Total Recoverable Cash Advances at 1st January 3,140 1,770 Total Recoverable Cash Advances 31 December 4,484 3,140 The Group receives government support in the form of recoverable cash advances from the Walloon Region in order to compensate the research and development costs incurred by the Group. At balance sheet date, the Group has been granted total recoverable cash advances amounting to €34.8 million. Out of this total amount : i) €26.3 million have been received to date ; ii) out of the active contracts, an amount of €7.0 million should be received in 2020 or later depending on the progress of the different programs partially funded by the Region ; and iii) an amount of €1.5 million refer to contracts for which the exploitation has been abandoned (and thus will not be received). For further details, reference is made to the table below which shows (i) the year for which amounts under those agreements have been received and initially recognized on the balance sheet for the financial liability and deferred grant income components and (ii) a description of the specific characteristics of those recoverable cash advances including repayment schedule and information on other outstanding advances. In 2020, the Group will be required to make exploitation decisions on the Group’s remaining outstanding RCA related to the CAR-T (in €‘000) Amounts received for the years Amounts to be received As at Id Project Contractual Prior 2018 2019 Cumulated 2020 Status Amount 5160 C-Cure 2,920 2,920 — — 2,920 — Abandoned — 5731 C-Cure 3,400 3,400 — — 3,400 — Abandoned — 5914 C-Cure 700 687 — — 687 — Abandoned 180 5915 C-Cath ez 910 910 — — 910 — Exploitation 530 5951 Industrialization 1,470 866 — — 866 — Abandoned 245 6003 C-Cure 1,729 1,715 — — 1,715 — Abandoned — 6230 C-Cure 1,084 1,084 — — 1,084 — Abandoned — 6363 C-Cure 1,140 1,126 — — 1,126 — Abandoned 1,536 6548 Industrialization 660 541 — — 541 — Abandoned — 6633 C-Cath ez 1,020 1,020 — — 1,020 — Exploitation 245 6646 Proteins 1,200 450 — — 450 — Abandoned 450 7027 C-Cath ez 2,500 2,500 — — 2,500 — Exploitation 375 7246 C-Cure 2,467 2,467 — — 2,467 — Abandoned — 7502 CAR-T 2,000 2,000 — — 2,000 — Exploitation 20 7685 THINK 3,496 873 1,187 1,086 3,146 350 Research — 8087 CYAD01-Deplethink 2,492 — — 623 623 1,869 Research — 8088 CYAD02-Cycle1 3,538 — — 885 885 2,654 Research — 1910028 CwalityCAR 2,102 — — — — 2,102 Research — Total 34,828 22,559 1,187 2,593 26,339 6,975 3,581 Regarding active contracts (in exploitation status): The contracts 5915 has the following specific characteristics: • funding by the Region covers 70% of the budgeted project costs; • certain activities have to be performed within the Region; • in case of an outlicensing agreement or a sale to a third party, the Group will have to pay 10% of the price received (excl. of VAT) to the Region; • sales-independent reimbursements, sales-dependent reimbursements, and amounts due in case of an outlicensing agreement or a sale to a third party, are, in the aggregate, capped at 100% of the principal amount paid out by the Region; • sales-dependent reimbursements payable in any given year can be set-off • the amount of sales-independent reimbursement and sales-dependent reimbursement may possibly be adapted in case of an outlicensing agreement, a sale to a third party or industrial use of a prototype or pilot installation, when obtaining the consent of the Walloon Region to proceed thereto. The other contracts have the following specific characteristics: • funding by the Region covers from 45 to 70% of the budgeted project costs; • certain activities have to be performed within the European Union; • sales-independent reimbursements represent in the aggregate 30% of the principal amount; • sales-independent reimbursements and sales-dependent reimbursements are, in the aggregate (including the accrued interests), capped at 200% of the principal amount paid out by the Region; • interests (at Euribor 1 year (as applicable on the first day of the month in which the decision to grant the relevant RCA was made + 100 basis points) accrue as of the 1st day of the exploitation phase; • the amount of sales-independent reimbursement and sales-dependent reimbursement may possibly be adapted in case of an outlicensing agreement, a sale to a third party or industrial use of a prototype or pilot installation, when obtaining the consent of the Region to proceed thereto. • in case of bankruptcy, the research results obtained by the Group under those contracts are expressed to be assumed by the Region by operation of law. The table below summarizes, in addition to the specific characteristics described above, certain terms and conditions for the recoverable cash advances: Contract Research phase Percentage Turnover- Turnover-independent reimbursement Interest rate accrual Amounts due in (€’000) 5160 01/05/05-30/04/08 70 % 0.18 % Consolidated with 6363 N/A N/A 5731 01/05/08-31/10/09 70 % 0.18 % Consolidated with 6363 N/A N/A 5914 01/09/08-30/06/11 70 % 5.00 % €30k in 2012 and €70k each year after N/A 10% with a minimum of 100/Y 5915 01/08/08-30/04/11 70 % 5.00 % €40k in 2012 and €70k each year after N/A 10% with a minimum of 100/Y 5951 01/09/08-31/12/14 70 % 5.00 % €100k in 2014 and €150k each year after N/A 10% with a minimum of 200/Y 6003 01/01/09-30/09/11 60 % 0.18 % Consolidated with 6363 N/A N/A 6230 01/01/10-31/03/12 60 % 0.18 % Consolidated with 6363 N/A N/A 6363 01/03/10-30/06/12 60 % 0.18 % From €103k to €514k starting in 2013 until 30% of advance is reached Starting on 01/01/13 N/A 6548 01/01/11-31/03/13 60 % 0.01 % From €15k to €29k starting in 2014 until 30% of advance is reached Starting on 01/10/13 N/A 6633 01/05/11-30/11/12 60 % 0.27 % From €10k to €51k starting in 2013 until 30% of advance is reached Starting on 01/06/13 N/A 6646 01/05/11-30/06/15 60 % 0.01 % From €12k to €60k starting in 2015 until 30% of advance is reached Starting on 01/01/16 N/A 7027 01/11/12-31/10/14 50 % 0.33 % From €25k to €125k starting in 2015 until 30% of advance is reached Starting on 01/01/15 N/A 7246 01/01/14-31/12/16 50 % 0,05 % From €30k to €148k starting in 2017 until 30% of advance is reached. Starting in 2017 N/A 7502 01/12/15-30/11/18 45 % 0.19 % From €20k to €50k starting in 2019 until 30% is reached. Starting 2019 N/A 7685 1/01/17-31/12/19 45 % 0.33 % From €35k to €70k starting in 2020 until 30% is reached. Starting 2020 N/A 8087 01/05/19-31/12/20 45 % 0.22 % From €25k to €75k starting in 2021 until 30% is reached Starting 01/01/21 N/A 8088 01/05/19-31/12/20 45 % 0.21 % From €35k to €106k starting in 2021 until 30% is reached Starting 01/01/21 N/A 1910028 06/06/19-05/05/21 45 % 0.01 % From €21k to €42k starting in 2022 until 30% is reached Starting 01/06/21 N/A

Due Dates of the Financial Liab

Due Dates of the Financial Liabilities	12 Months Ended
	Dec. 31, 2019
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Due Dates of the Financial Liabilities	NOTE 20: DUE DATES OF THE FINANCIAL LIABILITIES The table below analyses the Group’s non-derivative Financial liabilities reported as at December 31, 2019: (€‘000) Total Less than One to three Three to More than As at 31 December, 2019 Lease liabilities 4,838 1,401 1,952 1,100 385 Bank loan 229 192 37 — — Pension obligations 398 — — — 398 Advances repayable (current and non-current) 4,484 346 490 486 3,163 Total financial liabilities 9,949 1,939 2,479 1,586 3,946 Financial liabilities reported as at December 31, 2018: (€‘000) Total Less than One to five Three to More than As at 31 December, 2018 Finance leases 1,136 484 652 — — Operating leases 2,912 708 942 729 533 Bank loan 510 281 229 — — Pension obligations 131 — — — 131 Advances repayable (current and non-current) 3,140 276 717 560 1,587 Total - material contractual obligations 7,829 1,749 2,540 1,290 2,250

Trade Payables and Other Curren

Trade Payables and Other Current Liabilities	12 Months Ended
	Dec. 31, 2019
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Trade Payables and Other Current Liabilities	NOTE 21: TRADE PAYABLES AND OTHER CURRENT LIABILITIES (€‘000) As at 31 December, 2019 2018 Total Trade payables 6,969 5,916 Other current liabilities Social security 482 314 Payroll accruals and taxes 1,750 1,351 Other current liabilities 1,016 1,024 Total Other current liabilities 3,248 2,690 Total Trade payables and other current liabilities 10,217 8,606 Trade payables are non-interest-bearing 90-day The Other current liabilities include the short-term debts to employees and social welfare and tax agencies. No discounting was performed to the extent that the amounts do not present payments terms longer than one year at the end of each financial year presented.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2019
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Financial Instruments on Balance Sheet	NOTE 22: FINANCIAL INSTRUMENTS Financial instruments not reported at fair value The carrying and fair values of financial instruments that are not carried at fair value in the financial statements was as follows at December 31, for current and comparative year-ends: (€‘000) As of December 31, 2019 Loans and receivables Fair Financial Assets (‘Amortized cost’ category) within: Non-current 2,432 2,432 Other non-current 257 257 Trade receivables and other current assets 558 558 Short-term investments 0 0 Cash and cash equivalents 39,338 39,338 Total 42,586 42,586 For the above-mentioned financial assets, the carrying amount as per December 31, 2019 is a reasonable approximation of their fair value. (€‘000) As of December 31, 2019 Financial liabilities at amortized cost Fair value Financial Liabilities (‘Financial liabilities at amortized cost’ category) within: Bank loans 229 229 Lease liabilities 4,134 4,134 RCAs liability 4,484 4,484 Trade payables and other current liabilities 6,969 6,969 Total 15,759 15,759 For the above-mentioned financial liabilities, the carrying amount as per December 31, 2019 is a reasonable approximation of their fair value. As of December 31, 2018 (€‘000) Loans and receivables Fair Financial Assets (‘Amortized cost’ category) within: Non-current 1,743 1,743 Other non-current 215 215 Trade receivables and other current assets 367 367 Short-term investments 9,197 9,197 Cash and cash equivalents 40,542 40,542 Total 52,065 52,065 For the above-mentioned financial assets, the carrying amount as per December 31, 2018 is a reasonable approximation of their fair value. As of December 31, 2018 (€‘000) Financial liabilities at amortized cost Fair value Financial Liabilities (‘Financial liabilities at amortized cost’ category) within: Bank loans 510 510 Lease liabilities 1,136 1,136 RCAs liability 3,140 3,140 Trade payables and other current liabilities 5,916 5,916 Total 10,702 10,702 For the above-mentioned financial liabilities, the carrying amount as per December 31, 2018 is a reasonable approximation of their fair value. Financial instruments reported at fair value on balance sheet Contingent consideration and other financial liabilities are reported at fair value in the statement of financial position using Level 3 fair value measurements for which the Group developed unobservable inputs: (€‘000) Level I Level II Level III Total Assets Investment in equity securities 0 — — 0 Total Assets 0 — — 0 Liabilities — — — — Contingent consideration and other financial liabilities — — 24,754 24,754 Total Liabilities — — 24,754 24,754 The change in their balances is detailed as follows: CONTINGENT CONSIDERATION AND OTHER FINANCIAL LIABILITIES ROLL FORWARD (€‘000) For the year ended 2019 2018 Opening balance Contingent consideration at 1 January 20,282 15,549 Milestone payment — — Fair value adjustment (430 ) 4,733 Currency Translation Adjustment — — Closing balance Contingent consideration at 31 December 19,853 20,282 Opening balance Other financial liabilities at 1 January 4,905 4,034 Fair value adjustment (4 ) 871 Closing balance Other financial liabilities at 31 December 4,901 4,905 Total—Contingent consideration and Other financial liabilities at 31 December 24,754 25,187 The contingent consideration and other financial liabilities refer to the acquisition of the Group’s immuno-oncology platform and corresponds to the fair value of the potential future payments due to Celdara Medical, LLC and Dartmouth College. The liability evolution reflects the development of the Group’s product candidates using CAR-T The liability decrease at balance sheet date is due to the fair value adjustment at reporting date, mainly driven by discount rate (WACC) update and refinement on time-to-market year-end The contingent consideration liability captures the commitments disclosed under Note 31. It does not include any amount for contingent consideration payable relating to any sub-licensing • any contingent consideration payable would be due only when Celyad earns revenue from such sub-licensing • the development of the underlying product candidates by the sub-licensees Contingent consideration sensitivity analysis A sensitivity analysis has been performed on the key assumptions driving the fair value of the contingent consideration liability. The main drivers are i) the discount rate (WACC), ii) the sales long-term growth rate in the terminal value and iii) the probabilities of success (PoS) for the Group’s product candidates to get commercialized. Discount rate (WACC) 10.6% 12.6% 14.6% 16.6% 18.6% Cont. consideration (€ million) 32.2 28.2 24.8 21.9 19.5 Impact (%) 30 % 14 % — -12 % -21 % Sales long-term growth rate in the terminal value -40% -32.5% -25% -17.5% -10% Cont. consideration (€ million) 23.3 23.9 24.8 26.0 28.0 Impact (%) -6 % -3 % — 5 % 13 % To determine the contingent consideration liability, the Group used the same probabilities of success than for impairment testing purposes (see Note 7): PoS Phase I Phase I to II Phase II to III Phase III to NDA/BLA to Cumulated CYAD-01 CYAD-101 100 % 63 % 26 % 45 % 83 % 6.3 % In order to assess the sensitivity to this driver, the Group applies here an incremental probability factor to the bottom-line cumulative PoS disclosed below: Probabilities of Success -20% -10% PoS model 10% 20% Cont. consideration (€ million) 19.8 22.3 24.8 27.2 29.7 Impact (%) -20 % -10 % — 10 % 20 %

Changes in Liabilities Arising

Changes in Liabilities Arising from Financial Activities	12 Months Ended
	Dec. 31, 2019
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Changes in Liabilities Arising from Financial Activities	NOTE 23: CHANGES IN LIABILITIES ARISING FROM FINANCIAL ACTIVITIES The change in bank loans balances is detailed as follows: BANK LOANS FINANCIAL LIABILITY ROLL FORWARD (€‘000) For the year ended 2019 2018 Opening balance at 1 January 510 536 New bank loans — 220 Installments (281 ) (245 ) Closing balance at 31 December 229 510 The change in lease liability balances is detailed as follows: LEASES LIABILITY ROLL FORWARD (€‘000) For the year ended 2019 2018 Opening balance at 1 January 1,136 909 New leases 4,204 730 Installments (1,206 ) (503 ) Closing balance at 31 December 4,134 1,136 The change in recoverable cash advance liability balances is detailed as follows: RECOVERABLE CASH ADVANCE LIABILITY ROLL FORWARD (€‘000) For the year ended 2019 2018 Opening balance at 1 January 3,140 1,770 Repayments (256 ) (226 ) New Liability component 1,481 598 Remeasurement 120 998 Closing balance at 31 December 4,484 3,140 The change in the recoverable cash advances liability at balance sheet date reflects both the new liability components recorded during the year as well as the remeasurement of the liability at amortized cost, based on the Group’s updated business plan and sales forecast for the Group’s CAR-T year-end ez

Revenues and Net Other Income a

Revenues and Net Other Income and Expenses	12 Months Ended
	Dec. 31, 2019
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Revenues and Net Other Income and Expenses	NOTE 24: REVENUES AND NET OTHER INCOME AND EXPENSES (€‘000) For the year ended 31 December, 2019 2018 2017 Out-licensing — 2.399 3.505 C-CathEZ 6 — 35 Other revenue 0 716 — Total 6 3.115 3.540 In May 2018, the Group has entered into an exclusive license agreement with Mesoblast, an Australian biotechnology company, to develop and commercialize Celyad’s intellectual property rights relating to C-Cath ez 5-step • is a distinct component of the Mesoblast agreement; • refers to a ‘right-to-use’ • foresees a transaction price broken down between upfront (€0.8 million settled in shares) and contingent milestone payments (an additional amount of €2.2 million qualifying for recognition at December 31, 2018); • features a financing component (€0.5 million deferred financial income to be deducted from the above), leading to a net out-licensing • further foresees variable consideration of up to $17.5 million related to future regulatory- and commercial-based milestones, which will not be recognized until it becomes highly probable that a significant reversal in the amount of cumulative revenue recognized will not occur. The related receivable is reported for its discounted value (€1.9 million) under ‘Non-current The Group did not enter into such agreements for the 12-month In previous year, other revenue referred to a non-clinical year-end The Group does not expect to generate significant revenue unless and until it receives regulatory approval for one of the Group’s drug product candidates. Other expenses Other expenses mainly refer to remeasurement expenses of recoverable cash advances (RCAs). For the government grants received in the form of RCAs, see disclosure note 9. Other expenses decrease compared to prior year refers to the following drivers: • the fair value adjustment relating to the contingent consideration and other financial liabilities is an €0.4 million income at December 31, 2019 against a €5.6 million expense for the comparative period; • a clinical development milestone had been paid for an amount of €1.4 million in the comparative period; • decrease of remeasurement expense of RCAs, required by IFRS, for the current period. Other income Other income is mainly related to regional government grants received in 2019. For the regional government grants received in form of recoverable cash advances (RCAs) contract, numbered 7685, 8087, 8088 and 1910028 (amounting to a total of €1.5 million), refer to note 5.16 for more information. Additional grants income has been recognized in 2019 on grants received from Federal Belgian Institute for Health Insurance Inami (€0.2 million) and from regional government (contract numbered 8066 for €1.6 million), not referring to RCAs and not subject to reimbursement. The second driver of other income is the change in fair value of the contingent consideration and other financial liabilities (€0.4 million). See note 9 for more information. With respect to R&D tax credit, the current year income is predicated on a R&D tax credit recorded updated for a total for an amount of €1.6 million, taking into account all information available at this date. (€‘000) For the year ended 31 December, 2019 2018 2017 Remeasurement of contingent consideration — 5,604 — Clinical Development milestone payment 36 1,372 — Remeasurement of RCA’s 120 998 — Fair value adjustment on securities — 182 — Other 35 243 41 Total Other Expenses 191 8,399 41 (€‘000) For the year ended 31 December, 2019 2018 2017 Grant income (RCA’s) 1,508 768 824 Grant income (Other) 1,788 — 56 Remeasurement of RCA’s — — 396 Fair value adjustment on securities 182 — — Remeasurement of contingent consideration 433 — 193 R&D tax credit 1,560 310 1,161 Other 102 — — Total Other Income 5,572 1,078 2,630

Operating Expenses

Operating Expenses	12 Months Ended
	Dec. 31, 2019
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Operating Expenses	NOTE 25: OPERATING EXPENSES The operating expenses are made of the next three components: • Research & development expenses • General and administrative expenses • Non-recurring Research and development expenses The following table is a summary of manufacturing expenses, clinical, quality and regulatory expenses and other research and development expenses, which are aggregated and presented as research and development expenses in the Group’s consolidated financial statements. (€‘000) For the year ended 31 December, 2019 2018 2017 Employee expenses 8,362 7,902 7,007 Travel & Living 486 467 359 Clinical study costs 4,713 4,987 3,901 Preclinical study costs 3,711 2,680 1,820 Process development and scale-up 3,765 2,187 3.319 Consulting fees 675 1,522 1,429 IP filing and maintenance fees 260 474 564 Share-based payments 813 1,264 862 Depreciation 1,444 848 1,488 Rent and utilities 746 668 382 Delivery systems 53 117 430 External collaborations — — 812 Others 168 461 535 Total R&D expenses 25,196 23,577 22,908 Research and development expenses totaled €25.2 million for the 12-month CYAD-01, CYAD-02 CYAD-03 CYAD-101 CYAD-200 scale-up General and administrative expenses (€‘000) For the year ended 31 December, 2019 2018 2017 Employee expenses 3,542 3,312 2,630 Share-based payments 1,962 2,331 1,707 Rent & Insurances 625 1,097 1,053 Communication & Marketing 607 676 761 Consulting fees 1,532 2,192 2,227 Travel & Living 331 253 211 Post employment benefits (33 ) (3 ) — Depreciation 345 267 229 Other 159 263 490 Total General and administration 9,070 10,387 9,310 General and administrative expenses decreased by €1.3 million over the 12-month (non-cash Non-recurring Non-recurring one-off (€‘000) For the year ended 31 December 2019 2018 2017 Amendment of Celdara Medical and Dartmouth College agreements (24,341 ) C-Cure — — (6,045 ) C-Cure — — 5,356 Corquest IP asset impairment expenses — — (1,244 ) Write-off C-Cure — — (1,932 ) In 2017, the Group had recognized non-recurring non-cash write-off C-Cure

Employee Benefit Expenses

Employee Benefit Expenses	12 Months Ended
	Dec. 31, 2019
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Employee Benefit Expenses	NOTE 26: EMPLOYEE BENEFIT EXPENSES As of December 31, 2019, the Group employed 99 full-time employees, 2 part-time employees and 6 senior managers under management services agreements. The Group has never had a work stoppage, and none of the Group’s employees is represented by a labor organization or under any collective-bargaining arrangements. The Group considers its employee relations to be good. A split of the Group’s employees and consultants by main department and geography for the years ended December 31, 2019, 2018 and 2017 was as follows: At December 31, 2019 2018 2017 By function: Clinical & Regulatory, IP, Marketing 26 19 16 Research & Development 33 30 29 Manufacturing /Quality 32 34 26 General Administration 16 13 16 Total 107 96 87 By Geography: Belgium 103 91 83 United States 4 5 4 Total 107 96 87 (€‘000) For the year ended 31 December, 2019 2018 2017 Salaries, wages and fees 6,932 6,439 5,461 Executive Committee compensation 2,993 3,235 2,563 Share-based payments 2,775 3,595 2,569 Social security 1,473 1,301 1,277 Post-employment benefits 215 217 220 Hospitalization insurance 138 118 118 Other benefit expense 119 2 — Total Employee expenses 14,646 14,906 12,207 Total employee expenses slightly decreased compared to comparative year. This effect is mainly explained by the decrease on share-based payments vesting cost (non-cash year-on-year, The increase observed between 2018 and 2017 in Share-based payments vesting cost (non-cash mid-2017).

Leases

Leases	12 Months Ended
	Dec. 31, 2019
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Leases	NOTE 27: LEASES Amounts recognized in the consolidated statements of financial position “Property, plant and equipment” comprise owned and leased assets that do not meet the definition of investment property. (€’000) As of December 31, 2019 2018 Property, Plant and Equipment owned (excluding right-of-use 1,713 1,867 Right-of-use 3,348 1,147 Total Property, Plant and Equipment 5,061 3,014 The statement of financial position shows the following amounts relating to leases for which the Group is a lessee: (€’000) As of December 31, 2019 Property Vehicles Equipment Total Lease assets as per 31 December 2018 — — 1,147 1,147 Right-of-use 2,780 106 72 2,958 Opening balance at 1 January 2019 2,780 106 1,219 4,105 Additions for the period 30 257 — 287 Disposals for the period — — — — Depreciation charge for the period (399 ) (90 ) (555 ) (1,044 ) Closing balance at 31 December 2019 2,411 273 664 3,348 Amounts recognized in the consolidated statements of comprehensive loss The consolidated statements of comprehensive loss show the following amounts relating to leases: (€’000) For the year ended December 31, 2019 Depreciation charge of right-of-use Property 399 Vehicles 90 Equipment 555 Interest on lease liabilities (including in Financial expenses) 1 291 Interest on sublease receivable (including in Financial income) (62 ) Variable lease payments not included in the measurement of lease liabilities — Expenses relating to short-term leases and leases of low-value 182 Total expenses related to leases 1,450 1 Interests on leases are presented as operating cash flow. Total cash outflow for leases (€’000) For the year ended 2019 Total cash outflow for leases (including short-term leases and leases of low-value 1,679

Financial Income and Expenses

Financial Income and Expenses	12 Months Ended
	Dec. 31, 2019
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Financial Income and Expenses	NOTE 28: FINANCIAL INCOME AND EXPENSES The net financial result decreased from €0.7 million at year-end year-end • decrease by €0.2 million of net results on finance leases interests, through the first adoption of new accounting standard IFRS 16 Leases • decrease by €0.3 million on interest’s income on bank accounts through the Group decision to reduce the amounts invested in short-term deposits over 2019 given the level of market interest rates of corporate deposits of short-term maturities. (€’000) For the year ended 31 December, 2019 2018 2017 Interest on leases 291 18 18 Interest on overdrafts and other finance costs 35 29 36 Interest on RCAs 17 15 90 Foreign Exchange differences — — 4,309 Finance expenses 343 62 4,45 3 Finance income on the net investment in lease 62 — Interest income bank account 30 308 927 Foreign Exchange differences 326 387 — Other financial income 164 109 6 Finance income 582 804 933 Net Financial result 239 743 (3,520 )

Income Tax

Income Tax	12 Months Ended
	Dec. 31, 2019
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Income Tax	NOTE 29: INCOME TAX The Group reports income taxes in the income statement as detailed below: (€‘000) For the year ended 31 December 2019 2018 2017 Current tax (expense) / income 8 0 1 Deferred tax (expense) / income — — — Total income tax expense in profit or loss 8 0 1 The Group has a history of losses. For 2019, the Group is eligible to a minor tax debit. The following table shows the reconciliation between the effective and theoretical income tax at the nominal Belgian income tax rate of 29.58% for the year 2019 and 2018: (€‘000) For the year ended 31 December 2019 2018 2017 Loss before tax (28,640 ) (37,428 ) (56,396 ) — — Permanent differences — — Tax disallowed expenses 967 269 221 Share-based payment 2,775 3,595 2,569 — — Nominal tax rate 29.58 % 29.58 % 33.99 % Tax income at nominal tax rate 1 7,365 9,928 18,220 Deferred Tax assets not recognized (7,357 ) (9,928 ) (18,219 ) — — Effective tax expense 8 0 1 Effective tax rate 0 % 0 % 0 % 1 The difference in foreign tax rate in the US (22.83%) compared to the Belgian rate (29.58%) is not distinctively disclosed in this table due to non-materiality

Deferred Taxes

Deferred Taxes	12 Months Ended
	Dec. 31, 2019
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Deferred Taxes	NOTE 30: DEFERRED TAXES As having not yet reached the commercialization step, the Group accumulates tax losses that are carried forward indefinitely for offset against future taxable profits of the Group. Significant uncertainty exists however surrounding the Group’s ability to realize taxable profits in a foreseeable future. Therefore, the Group has not recognized any deferred tax income in its income statement. Unrecognized deferred tax assets and liabilities are detailed below by nature of temporary differences for the current year: (€‘000) For the year ended 31 December 2019 Assets Liabilities Net Intangibles assets — (894 ) (894 ) Tangible assets — (90 ) (90 ) Recoverable cash advances liability 1,056 — 1,056 Contingent consideration liability 6,189 — 6,189 Employee Benefits liability 100 — 100 Other temporary difference — (473 ) (473 ) Tax-losses 55,414 — 55,414 — — — Unrecognized Gross Deferred Tax assets/(liabilities) 62,758 (1,458 ) 61,300 Netting by tax entity (1,365 ) 1,365 — Unrecognized Net Deferred Tax assets/(liabilities) 61,393 (93 ) 61,300 Unrecognized deferred tax assets and liabilities are detailed below by nature of temporary differences for the previous years: For the year ended 31 December 2018 (€‘000) Assets Liabilities Net Intangibles assets 49 — 49 Tangible assets — (154 ) (154 ) Recoverable cash advances liability 633 — 633 Contingent consideration liability 6,297 — 6,297 Employee Benefits liability 33 — 33 Other temporary difference — (436 ) (436 ) Tax-losses 46,858 — 46,858 — — — Unrecognized Gross Deferred Tax assets/(liabilities) 53,869 (590 ) 53,279 Netting by tax entity (437 ) 437 — Unrecognized Net Deferred Tax assets/(liabilities) 53,432 (153 ) 53,279 For the year ended 31 December 2017 (€‘000) Assets Liabilities Net Intangibles assets — (3,974 ) (3,974 ) Tangible assets — (215 ) (215 ) Recoverable cash advances liability 349 — 349 Contingent consideration liability 4,471 — 4,471 Employee Benefits liability 51 — 51 Other temporary difference 5 — 5 Tax-losses 48,152 — 48,152 Unrecognized Gross Deferred Tax assets/(liabilities) 53,028 (4,189 ) 48,839 Netting by tax entity (3,974 ) 3,974 — Unrecognized Net Deferred Tax assets/(liabilities) 49,054 (215 ) 48,839 The Group’s main deductible tax base relates to tax losses carried forward, which have indefinite term under both BE and US tax regimes applicable to the Group’s subsidiaries. In addition, the Group can benefit from additional tax benefits (like notional interest deduction in Belgium) which can be carried-forward until the taxation year 2020. The remaining temporary differences refer to differences between IFRS accounting policies and local tax reporting policies. The Group has not recognized any deferred tax asset on its balance sheet, for the same reason as explained above (uncertainty relating to taxable profits in a foreseeable future). The change in the Group’s unrecognized deferred tax asset balance is detailed below: UNRECOGNISED DEFERRED TAX ASSET BALANCE ROLL FORWARD (€‘000) For the year ended 2019 2018 2017 Opening balance at 1 January 53,279 48,839 39,370 Temporary difference creation or reversal (536 ) 5,734 (15,580 ) Change in Tax-losses 8,556 (1,294 ) 44,011 Foreign exchange rate effect — — (113 ) Change in BE tax rate applicable (34% > 25%) — — (14,896 ) Change in US tax rate applicable (35% > 23%) — — (3,953 ) — Closing balance at 31 December 61,300 53,279 48,839 The net increase in the balance mainly relates to the additional losses reported for the current year.

Commitments

Commitments	12 Months Ended
	Dec. 31, 2019
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Commitments	NOTE 31: COMMITMENTS Corquest Inc Based on the terms of the Share Purchase Agreement dated 5 November 2014, former shareholders of Corquest Inc will be entitled to an earn-out As from the 5 November 2014 date until the tenth anniversary of the Agreement, former shareholders of Corquest Inc are entitled to: • an Earn-Out • or an Earn-Out Celdara Medical LLC Milestones (formerly OnCyte LLC) Based on the terms of the Asset Purchase Agreement dated January 21, 2015, as amended on August 3, 2017, Celdara Medical LLC is entitled to development and regulatory milestones, sales milestones and royalties based on the net sales generated by the Group from products candidate, whose level depend on whether or not the licensed asset from which the product candidate is derived was in clinical or preclinical stage upon in-licensing On the clinical assets (NKG2D), Celdara Medical will be entitled to the following development and regulatory milestones; $5 million upon enrolment of the first patient of the second cohort of the Phase I trial 5 $6 million upon dosing the first patient of a Phase II trial 6 $9 million upon dosing the first patient of a Phase III trial $11 million upon filing of the first regulatory approval of CAR-T $14 million upon CAR-T On the other preclinical assets (TIM, B7H6, NKP30): $1.5 million upon an IND filing to the FDA 7 $4 million upon dosing the first patient of a Phase II trial $6 million upon dosing the first patient of a Phase III trial $10 million upon filing of the first regulatory request for the product candidate $15 million upon product candidate approval for commercialization in the US Sales milestones will also be due to Celdara Medical and are dependent of cumulative net sales of products developed from licensed assets: $15 million when first time cumulative worldwide net sales equal to or exceed $250 million $25 million when first time cumulative worldwide net sales equal to or exceed $500 million $40 million when first time cumulative worldwide net sales equal to or exceed $1 billion Group will make annual royalty payments to Celdara Medical on net sales of each product sold by the Group, its affiliates and sublicensees at the applicable rate set forth below: 5% of the net sales if cumulative worldwide annual net sales are less or equal to $250 million 6% of the net sales if cumulative worldwide annual net sales are greater than $250 million and less or equal to $500 million 7% of the net sales if cumulative worldwide annual net sales are greater than $500 million and less or equal to $1 billion 8% of the net sales if cumulative worldwide annual net sales are greater than $1 billion On all sublicensing revenues received, the Group will pay percentages ranging from 23% to 5% depending on the stage of development of the product sublicensed. On top of the amounts and percentages due to Celdara Medical LLC, the Group will owe to Dartmouth College an additional 2% royalties on its direct net sales. 5 Paid as of December 31, 2016 6 Paid as of December 31, 2017 7 Paid as of December 31, 2018, for TIM pre-clinical In accordance with IFRS 3, these contingencies are recognized on balance sheet at year-end, Horizon Discovery Limited The deal structure with Horizon Discovery entails two agreements. Based on the terms of the R&D Collaboration and License agreement dated April 3, 2018, Horizon Discovery Limited is entitled to development milestones and royalties based on the net sales generated by the Group from the Product. On the First Product, Horizon Discovery Limited will be entitled to the following development milestones: $ 100 000 upon the Group’s exercise of the Option 8 $100,000 upon the first effective IND, filed by the Group, relating to the First Product 9 $200,000 upon filing by the Group for the first Phase 2 Clinical Trial relating to the first Product $400,000 upon filing by the Group for the first Phase 3 Clinical Trial relating to the first Product $1.25 million upon filing by the Group of the first MAA or NDA relating to the first Product $2 million upon first MAA or NDA approval by the relevant Regulatory Authority for the first Product Group will make annual royalty payments to Horizon Discovery Limited of 1.5% on net sales of each product sold by the Group or its affiliates. In case the Group sublicenses all or part of its rights, then the Sublicensee shall pay royalties directly to Horizon at 1.25% on Sublicensees’ net sales of the product. Based on the terms of the R&D Collaboration and License agreement dated June 27, 2018, as amended on December 19, 2018, Horizon Discovery Limited is entitled to development milestones and royalties based on the net sales generated by the Group from the Product. On the First Product, Horizon Discovery Limited will be entitled to the following development milestones: $1.25 million upon the Group’s exercise of the Option 10 $200,000 upon the first effective IND, filed by the Group, relating to the First Product $500,000 upon enrollment of the first patient in a Phase 2 Clinical Trial relating to the first Product $800,000 upon enrollment of the first patient in a Phase 3 Clinical Trial relating to the first Product $2 million upon filing by the Group of the first MAA or NDA relating to the first Product $3 million upon first MAA or NDA approval by the relevant Regulatory Authority for the first Product On the second Product, Horizon Discovery Limited will be entitled to the following development milestones: $200,000 upon the first effective IND, filed by the Group, relating to the second Product $400,000 upon enrollment of the first patient in a Phase 2 Clinical Trial relating to the second Product $450,000 upon enrollment of the first patient in a Phase 3 Clinical Trial relating to the second Product $700,000 upon filing by the Group of the first MAA or NDA relating to the second Product $2 million upon first MAA or NDA approval by the relevant Regulatory Authority for the second Product 8 Paid as of December 31, 2019 9 Paid as of December 31, 2019 10 Paid as of December 31, 2019 On the third Product, Horizon Discovery Limited will be entitled to the following development milestones: $100,000 upon the first effective IND, filed by the Group, relating to the third Product $200,000 upon enrollment of the first patient in a Phase 2 Clinical Trial relating to the third Product $250,000 upon enrollment of the first patient in a Phase 3 Clinical Trial relating to the third Product $300,000 upon filing by the Group of the first MAA or NDA relating to the third Product $1 million upon first MAA or NDA approval by the relevant Regulatory Authority for the third Product Group will make annual royalty payments to Horizon Discovery Limited of 2% on net sales of each product sold by the Group or its affiliates. In case the Group sublicenses all or part of its rights, then the Group shall pay to Horizon 15% of all upfront payments, development milestones associated with filing for or receiving MAA and royalties which the Group shall receive from the Sublicensee.

Relationships with Third-Partie

Relationships with Third-Parties	12 Months Ended
	Dec. 31, 2019
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Relationships with Third-Parties	NOTE 32: RELATIONSHIPS WITH THIRD-PARTIES Remuneration of key management Key management consists of the members of the Executive Committee and the entities controlled by any of them. As at 31 December, 2019 2018 2017 Number of EMT members 6 7 8 (€’000) For the year ended 31 December 2019 2018 2017 Short term employee benefits [1] 1,112 740 666 Post employee benefits 26 16 14 Share-based compensation 1,005 1,794 1,123 Other employment costs [2] 75 27 30 Management fees 1,789 2,457 1,950 Total benefits 4,006 5,034 3,783 [1] Include salaries, social security, bonuses, lunch vouchers [2] Such as Company cars As at 31 December, 2019 2018 2017 Number of warrants granted 136,500 30,000 179,000 Number of warrants lapsed — — (15,225 ) Cumulative outstanding warrants 295,500 259,000 306,500 Exercised warrants — — 168,000 Outstanding payables (in ‘000€) — 803 461 Transactions with non-executive For the year ended 31 December, (€‘000) 2019 2018 2017 Share-based compensation 430 420 485 Management fees 429 357 387 Total benefits 859 776 872 As at 31 December, 2019 2018 2017 Number of warrants granted 100,000 20,000 60,000 Number of warrants lapsed 5,000 — (2,904 ) Number of exercised warrants — — — Cumulative outstanding warrants 190,000 135,000 115,000 Outstanding payables (in ‘000€) 210 127 194 Shares owned 345,453 345,453 2,512,004 Shares owed : info from Philippe Dechamps (D&O formulaires) Transactions with shareholders There were no transactions with Group’s shareholders, for both current and prior years.

Loss per share

Loss per share	12 Months Ended
	Dec. 31, 2019
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Loss per share	NOTE 33: LOSS PER SHARE The loss per share is calculated by dividing loss for the year by the weighted average number of ordinary shares outstanding during the period. As the Group is incurring net losses, outstanding warrants have an anti-dilutive effect. As such, there is no difference between the basic and the diluted earnings per share. In case the warrants would be included in the calculation of the loss per share, this would decrease the loss per share. (€’000) As at 31 December, 2019 2018 2017 Loss of the year attributable to Equity Holders (28,632 ) (37,427 ) (56,395 ) Weighted average number of shares outstanding 12,523,166 11,142,244 9,627,601 Earnings per share (non-fully (2.29 ) (3.36 ) (5.86 ) Outstanding warrants 1,292,380 731,229 674,962

Events after the close of the f

Events after the close of the fiscal Year	12 Months Ended
	Dec. 31, 2019
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Events after the close of the fiscal Year	NOTE 34: EVENTS AFTER THE CLOSE OF THE FISCAL YEAR On March 11, 2020 the World Health Organization declared the novel strain of coronavirus (COVID-19) COVID-19 With COVID-19 COVID-19 COVID-19, non-essential in-person Further, timely enrollment in clinical trials is reliant on clinical trial sites which may be adversely affected by global health matters, including, among other things, pandemics such as COVID-19. COVID-19. COVID-19 • the diversion of healthcare resources away from the conduct of clinical trial matters to focus on pandemic concerns, including the attention of physicians serving as Group’s clinical trial investigators, hospitals serving as its clinical trial sites and hospital staff supporting the conduct of its clinical trials; • limitations on travel that interrupt key trial activities, such as clinical trial site initiations and monitoring; • interruption in global shipping affecting the transport of clinical trial materials, such as investigational drug product used in our trials; and • employee absences that delay necessary interactions with local regulators, ethics committees and other important agencies and contractors. The impact of COVID-19 There were no other subsequent events that occur between 2019 year-end

Accounting Principles (Policies

Accounting Principles (Policies)	12 Months Ended
	Dec. 31, 2019
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Subsidiaries	Subsidiaries Subsidiaries are all entities (including structured entities) over which the Group has control. The Group controls an entity when the Group is exposed to, or has rights to, variable returns from its involvement with the entity and 2 The uncertainly raised by the COVID-19 3 ‘Treasury position’ is an alternative performance measure determined by adding Short-term investments and Cash and cash equivalents from the statement of financial position prepared in accordance with IFRS. has the ability to affect those returns through its power over the entity. Subsidiaries are fully consolidated from the date on which control is transferred to the Group. They are deconsolidated from the date control ceases. Inter-company transactions, balances and unrealized gains on transactions between group companies are eliminated. Unrealized losses are also eliminated. When necessary, amounts reported by subsidiaries have been adjusted to conform with the Group’s accounting policies.
Business Combinations	Business Combinations The Group applies the acquisition method to account for business combinations. The consideration transferred for the acquisition of a subsidiary is measured at the aggregate of the fair values of the assets transferred, the liabilities incurred or assumed, and the equity interests issued by the Group at the date of the acquisition. The consideration transferred includes the fair value of any asset or liability resulting from a contingent consideration arrangement. Identifiable assets acquired and liabilities and contingent liabilities assumed in a business combination are measured initially at their fair values at the acquisition date. Acquisition-related costs are expensed as incurred. Any contingent consideration to be transferred by the Group is recognized at fair value at the acquisition date. Subsequent changes to the fair value of the contingent consideration that is deemed to be an asset or liability is recognized in profit or loss, in accordance with IFRS 9 if applicable. Contingent consideration that is classified as equity is not re-measured,
Foreign currency translation	FOREIGN CURRENCY TRANSLATION Functional and presentation currency Items included in the financial statements of each of the Group’s entities are measured using the currency of the primary economic environment in which the entity operates (“the functional currency”). The consolidated financial statements are presented in Euros, which is the Group’s presentation currency. Transactions and balances Foreign currency transactions (mainly USD) are translated into the functional currency using the applicable exchange rate on the transaction dates. Monetary assets and liabilities denominated in foreign currencies are retranslated at the functional currency spot rate of exchange ruling at the reporting date. Foreign currency exchange gains and losses arising from settling foreign currency transactions and from the retranslation of monetary assets and liabilities denominated in foreign currencies at the reporting date are recognized in the income statement. Non-monetary Non-monetary Group companies The results and financial position of all group entities that have a functional currency different from the presentation currency are translated into the presentation currency as follows: • Assets and liabilities for each balance sheet presented are translated at the closing rate at the date of that balance sheet; • Income and expenses for each income statement are translated at average exchange rate (unless this average is not a reasonable approximation of the cumulative effect of the rates prevailing on the transaction dates, in which case income and expenses are translated at the rate on the dates of the transactions); and • All resulting translation differences are recognized in other comprehensive income.
Revenue	REVENUE So far, the main revenue generated by the Group relates to the sale of licenses.
Licensing revenue	Licensing revenue The Group enters into license and/or collaboration agreements with third-party biopharmaceutical partners. Revenue under these arrangements may include non-refundable Upfront payments License fees representing non-refundable Milestone payments Milestone payments represent amounts received from the Group’s customers or collaborators. The receipt of which is dependent upon the achievement of certain scientific, regulatory, or commercial milestones. Under IFRS 15, milestone payments generally represent a form of variable consideration as the payments are likely to be contingent on the occurrence of future events. Milestone payments are estimated and included in the transaction price based on either the expected value (probability-weighted estimate) or most likely amount approach. The most likely amount is likely to be most predictive for milestone payments with a binary outcome (i.e., the Group receives all or none of the milestone payment). Variable consideration is only recognized as revenue when the related performance obligation is satisfied, and the Group determines that it is highly probable that there will not be a significant reversal of cumulative revenue recognized in future periods. Royalty revenue Royalty revenues arise from the Group’s contractual entitlement to receive a percentage of product sales achieved by co-contracting co-contracting Sales of goods (medical devices) Sales of medical devices are recognized when the Group has fulfilled the performance obligations under the terms of the sales contract, which includes delivery of the promised goods. Sales of medical devices generated by the Group until 2017 are associated with C-Cath ez
Government Grants (Other operating income)	GOVERNMENT GRANTS (OTHER OPERATING INCOME ) The Group’s grant income reported under ‘Other income’ in the consolidated income statement is generated from: (i) recoverable cash advances (RCAs) granted by the Regional government of Wallonia; (ii) R&D tax credits granted by the Belgian federal government; and (iii) grants received from the European Commission under the Seventh Framework Program (“FP7”) and from Regional authorities. Government grants are recognized at their fair value where there is reasonable assurance that the grant will be received, and the Group will comply with all attached conditions. Once a government grant is recognized, any related contingent liability (or contingent asset) is treated in accordance with IAS 37. Government grants relating to costs are deferred and recognized in the income statement over the period necessary to match them with the costs that they are intended to compensate. Recoverable cash advances (RCAs) The Group receives grants from the Walloon Region in the form of recoverable cash advances (RCAs). RCAs are dedicated to support specific development programs. All RCA contracts, in essence, consist of three phases, i.e., the “research phase”, the “decision phase” and the “exploitation phase”. During the research phase, the Group receives funds from the Region based on statements of expenses. In accordance with IAS 20.10A and IFRS Interpretations Committee (IC)’s conclusion that contingently repayable cash received from a government to finance a research and development (R&D) project is a financial liability under IAS 32, ‘Financial instruments; Presentation’, the RCAs are initially recognized as a financial liability at fair value, determined as per IFRS 9/IAS 39. The benefit (RCA grant component) consisting in the difference between the cash received (RCA proceeds) and the above-mentioned financial liability’s fair value (RCA liability component) is treated as a government grant in accordance with IAS 20. The RCA grant component is recognized in profit or loss on a systematic basis over the periods in which the entity recognizes the underlying R&D expenses subsidized by the RCA. The RCAs liability component (RCA financial liability) is subsequently measured at amortized cost using the cumulative catch-up At the end of the research phase, the Group should within a period of six months decide whether or not to exploit the results of the research phase (decision phase). The exploitation phase may have a duration of up to 10 years. In the event the Group decides to exploit the results under an RCA, the relevant RCA becomes contingently refundable, and the fair value of the RCA liability adjusted accordingly, if required. When the Group does not exploit (or ceases to exploit) the results under an RCA, it has to notify the Region of this decision. This decision is of the sole responsibility of the Group. The related liability is then discharged by the transfer of such results to the Region. Also, when the Group decides to renounce to its rights to patents which may result from the research, title to such patents will be transferred to the Region. In that case, the RCA liability is extinguished. R&D Tax credits Since 2013, the Group applies for R&D tax credit, a tax incentive measure for European SME’s set-up Considering that R&D tax credits are ultimately paid by the public authorities, the related benefit is treated as a government grant under IAS 20 and booked into other income, in order to match the R&D expenses subsidized by the grant. Other government grants The Group has received and will continue to apply for grants from European (FP7) and Regional authorities. These grants are dedicated to partially finance early stage projects such as fundamental research, applied research, prototype design, etc. To date, all grants received are not associated with any conditions. As per each grant contract, grants are paid upon submission by the Group of a statement of eligible expenses. The Group incurs project expenses first and asks for partial refunding according to the terms of the contracts. These government grants are recognized in profit or loss on a systematic basis over the periods in which the entity recognizes the underlying R&D expenses subsidized.
Intangible assets	INTANGIBLE ASSETS The following categories of intangible assets apply to the current Group operations: Separately acquired intangible assets Intangible assets acquired from third parties are recognized at cost, if and only if it is probable that future economic benefits associated with the asset will flow to the Group, and that the cost can be measured reliably. Following initial recognition, intangible assets are carried at cost less any accumulated amortization and accumulated impairment losses. The useful life of intangible assets is assessed as finite, except for Goodwill and IPRD assets (discussed below). They are amortized over the expected useful economic life and assessed for impairment whenever there is an indication that the intangible asset may be impaired. The amortization period and the amortization method for an intangible asset with a finite useful life are reviewed at least at each financial year end. Changes in the expected useful life or the expected pattern of consumption of future economic benefits embodied in the asset is accounted for by changing the amortization period or method, as appropriate, and are treated as changes in accounting estimates. The amortization expense on intangible assets with finite lives is recognized in the income statement in the expense category consistent with the function of the intangible asset.
Patents, Licences and Trademarks	Patents, Licenses and Trademarks Licenses for the use of intellectual property are granted for a period corresponding to the intellectual property of the assets licensed. Amortization is calculated on a straight-line basis over this useful life. Patents and licenses are amortized over the period corresponding to the IP protection and are assessed for impairment whenever there is an indication these assets may be impaired. Indication of impairment is related to the value of the patent demonstrated by the pre-clinical
Software	Software Software only concerns acquired computer software licenses. Software is capitalized on the basis of the costs incurred to acquire and bring to use the specific software. These costs are amortized over their estimated useful lives of three to five years on a straight-line basis.
Goodwill	Goodwill Goodwill is an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Goodwill is measured as a residual at the acquisition date, as the excess of the fair value of the consideration transferred and the assets and liabilities recognized (in accordance with IFRS 3). Goodwill has an indefinite useful life and is not amortized but tested for impairment at least annually or more frequently whenever events or changes in circumstances indicate that goodwill may be impaired, as set forth in IAS 36 (Impairment of Assets). Goodwill arising from business combinations is allocated to cash generating units, which are expected to receive future economic benefits from synergies that are most likely to arise from the acquisition. These cash generating units form the basis of any future assessment of impairment of the carrying value of the acquired goodwill.
In process research and development costs	In-process The In-process Subsequent R&D expenditure can be capitalized as part of the IPRD only to the extent that IPRD is in development stage, i.e. when such expenditure meets the recognition criteria of IAS 38. In line with biotech industry practice, the Group determines that ‘development stage’ under IAS 38 is reached when the product candidate gets regulatory approval (upon Phase III completion). Therefore, any R&D expenditure incurred between the acquisition date and the development stage should be treated as part of research phase and expensed periodically in the income statement.
Research and development costs	Research and development costs Research costs are expensed as incurred. Development expenditures on an individual project are recognized as an intangible asset when the Group can demonstrate: a) the technical feasibility of completing the intangible asset so that it will be available for use or sale. b) its intention to complete the intangible asset and use or sell it. c) its ability to use or sell the intangible asset. d) how the intangible asset will generate probable future economic benefits. Among other things, the entity can demonstrate the existence of a market for the output of the intangible asset or the intangible asset itself or, if it is to be used internally, the usefulness of the intangible asset. e) the availability of adequate technical, financial and other resources to complete the development and to use or sell the intangible asset. f) its ability to measure reliably the expenditure attributable to the intangible asset during its development. For the industry in which the Group operates, the life science industry, criteria a) and d) tend to be the most difficult to achieve. Experience shows that in the Biotechnology sector technical feasibility of completing the project is met when such project completes successfully Phase III of its development. For medical devices this is usually met at the moment of CE marking. Following initial recognition of the development expenditure as an asset, the cost model is applied requiring the asset to be carried at cost less any accumulated amortization and accumulated impairment losses. Amortization of the asset begins when development has been completed and the asset is available for use. It is amortized over the period of expected future benefit. Amortization is recorded in Research & Development expenses. During the period of development, the asset is tested for impairment annually, or earlier when an impairment indicator occurs. As of balance sheet date, only the development costs of C-Cath ez
Property, plant and equipment	PROPERTY, PLANT AND EQUIPMENT Plant and equipment are stated at cost, net of accumulated depreciation and/or accumulated impairment losses, if any. Repair and maintenance costs are recognized in the income statement as incurred. Depreciation is calculated on a straight-line basis over the estimated useful life of the asset as follows: • Land and buildings: 15 to 20 years • Plant and equipment: 5 to 15 years • Laboratory equipment: 3 to 5 years • Office furniture: 3 to 10 years • Leasehold improvements: based on remaining duration of office building lease • Right-of-use An item of property, plant and equipment and any significant part initially recognized is derecognized upon disposal or when no future economic benefits are expected from its use or disposal. Any gain or loss arising on derecognition of the asset (calculated as the difference between the net disposal proceeds and the carrying amount of the asset) is included in the income statement when the asset is derecognized. The assets’ residual values, useful lives and methods of depreciation are reviewed at each financial year end, and adjusted prospectively, if applicable.
Leases	LEASES The determination of whether an arrangement is, or contains, a lease is based on the substance of the arrangement at inception date whether fulfilment of the arrangement is dependent on the use of a specific asset or assets or the arrangement conveys a right to use the asset. The Group leases various offices, facilities, cars and IT-equipment. Until the 2018 financial year, leases of property, plant and equipment were classified as either finance or operating leases. Payments made under operating leases (net of any incentives received from the lessor) were charged to profit or loss on a straight-line basis over the period of the lease. From 1 January 2019, leases are recognized as a right-of-use right-of-use Assets and liabilities arising from a lease are initially measured on a present value basis. Lease liabilities include the net present value of the following lease payments: • fixed payments (including in-substance • variable lease payment that are based on an index or a rate; • amounts expected to be payable by the lessee under residual value guarantees; • the exercise price of a purchase option if the lessee is reasonably certain to exercise that option; and • payments of penalties for terminating the lease, if the lease term reflects the lessee exercising that option. The lease term covers the non-cancellable (a) periods covered by an option to extend the lease if the Group is reasonably certain to exercise that option; and (b) periods covered by an option to terminate the lease if the Group is reasonably certain not to exercise that option. The lease payments are discounted using the interest rate implicit in the lease. If that rate cannot be determined, the lessee’s incremental borrowing rate is used, being the rate that the lessee would have to pay to borrow the funds necessary to obtain an asset of similar value in a similar economic environment with similar terms and conditions. Right-of-use • the amount of the initial measurement of lease liability; • any lease payments made at or before the commencement date less any lease incentives received; • any initial direct costs; and • restoration costs. Payments associated with short-term leases and leases of low-value Low-value IT-equipment. The Group subleases some office space it leases from a head lessor. In its capacity as intermediate lessor, the Group assesses whether the sublease is a finance or operating lease in the context of the right-of-use right-of-use right-of-use From time to time, the Group may enter into sale and leaseback transactions. When a sale occurs, both the seller-lessee and the buyer-lessor account for the leaseback in the same manner as any other lease. Specifically, the seller-lessee recognizes a lease liability and right-of-use low-value Adjustments recognized on adoption of IFRS 16 The Group has adopted IFRS 16 modified retrospective approach from January 1, 2019 but has not restated comparatives for the 2018 reporting period, as permitted under the specific transitional provisions in the standard. The reclassifications and the adjustments arising from the new lease accounting principles are therefore recognized in the opening balance sheet on January 1, 2019. On adoption date, lease liabilities were measured at the present value of the remaining lease payments, discounted at the Group’s incremental borrowing rate as at 1 January 2019 (weighted-average rate applied was 7.5%). The right-of-use right-of-use The Group used the following practical expedients when applying IFRS 16 to leases previously classified as operating leases under IAS 17: • application of a single discount rate to a portfolio of lease with similar characteristics; • exclusion of initial direct costs from measuring the right-of-use • use of hindsight when determining the lease term if the contract contains options to extend or terminate the lease. On January 1, 2019, the Group recognized an additional lease liability of €3.9 million primarily relating to its headquarter offices as well as R&D and manufacturing facilities, and an increase in right-of-use The transition impact is detailed as follows: (€’000) Operating leases commitments disclosed—31 December 2018 2,912 Future minimum sublease income offset against amount of operating lease commitments previously disclosed [1] 1,078 Adjustment as a result of different treatment of extension options 957 ‘Low-value [2] (137 ) Operating leases commitments as per IFRS 16 scope 4,810 Discounting effect incremental borrowing rate (928 ) IFRS 16 lease liability (discounted) recognized at transition date—1 January 2019 3,882 IFRS 16 lease liability (non-current)—1 3,208 IFRS 16 lease liability (current)—1 January 2019 674 [1] This relates to a real estate property lease in which the Group acts as an intermediate lessor between a head lessor and a sublessee. [2] IFRS 16 scope exemptions, as commented above.
Impairment of non-financial assets	IMPAIRMENT OF NON-FINANCIAL The Group assesses at each reporting date whether there is an indication that an asset may be impaired. If any indication exists, or when annual impairment testing for an asset is required, the Group estimates the asset’s recoverable amount. An asset’s recoverable amount is the higher of an asset’s or cash-generating unit’s (CGU) fair value less costs to sell and its value in use and is determined for an individual asset, unless the asset does not generate cash inflows that are largely independent of those from other assets or group of assets. In assessing value in use, the estimated future cash flows are discounted to their present value using a pre-tax cash-flow Where the carrying amount of an asset or CGU exceeds its recoverable amount, an impairment loss is immediately recognized as an expense and the asset carrying value is written down to its recoverable amount. An assessment is made at each reporting date as to whether there is any indication that previously recognized impairment losses may no longer exist or may have decreased. If such indication exists, the Group estimates the asset’s or cash-generating unit’s recoverable amount. A previously recognized impairment loss is reversed only if there has been a change in the assumptions used to determine the asset’s recoverable amount since the last impairment loss was recognized. The reversal is limited so that the carrying amount of the asset does not exceed its recoverable amount, nor exceed the carrying amount that would have been determined, net of depreciation, had no impairment loss been recognized for the asset in prior years. Such reversal is recognized in the income statement unless the asset is carried at a revalued amount, in which case the reversal is treated as a revaluation increase. An impairment loss recognized on goodwill is however not reversed in a subsequent period. As of balance sheet date, the Group has two cash-generating units which consist of the development and commercialization activities on: • CYAD products candidate series based on CAR-T • C-Cath ez Indicators of impairment used by the Group are the pre-clinical
Cash and cash equivalents	CASH AND CASH EQUIVALENTS Cash and cash equivalents in the statement of financial position comprise cash at banks and on hand and very short-term deposits with an original maturity of one month or less. Cash and cash equivalents are carried in the balance sheet at their nominal value.
Financial assets	FINANCIAL ASSETS Classification The Group classifies its financial assets in accordance with IFRS 9 categories for measurement purposes. The classification depends on the purpose for which the financial assets were acquired. Management determines the classification of its financial assets at initial recognition. ‘Amortized cost’ measurement category refers to loans and receivables which are non-derivative non-current “(non-) “(non-) (non-) Initial recognition and measurement All financial assets are recognized initially at fair value plus or minus, in the case of a financial asset not at fair value through profit or loss, directly attributable transaction costs. Subsequent measurement After initial measurement, financial assets are subsequently measured at amortized cost using the effective interest rate method (EIR), less impairment. Amortized cost is calculated by taking into account any discount or premium on acquisition and fee or costs that are an integral part of the EIR. The EIR amortization is included in finance income in the income statement. The losses arising from impairment are recognized in the income statement. Impairment of financial assets In relation to the impairment of financial assets, IFRS 9 requires an expected credit loss model. The expected credit loss model requires the Group to account for expected credit losses and changes in those expected credit losses at each reporting date to reflect changes in credit risk since initial recognition of the financial assets. In other words, it is no longer necessary for a credit event to have occurred before credit losses are recognized. Specifically, IFRS 9 requires the Group to recognize a loss allowance for expected credit losses on trade receivables and contract assets. In particular, IFRS 9 requires the Group to measure the loss allowance for a financial instrument at an amount equal to the lifetime expected credit losses (ECL) if the credit risk on that financial instrument has increased significantly since initial recognition, or if the financial instrument is a purchased or originated credit-impaired credit-impaired 12-months Given the current nature and size of operations of the Group, these requirements mainly apply to the financial assets reported under ‘non-current Financial assets carried at amortized cost For financial assets carried at amortized cost the Group first assesses individually whether objective evidence of impairment exists individually for financial assets that are individually significant, or collectively for financial assets that are not individually significant. If the Group determines that no objective evidence of impairment exists for an individually assessed financial asset, it includes the asset in a group of financial assets with similar credit risk characteristics and collectively assesses them for impairment. Assets that are individually assessed for impairment and for which an impairment loss is, or continues to be, recognized are not included in a collective assessment of impairment. If there is objective evidence that an impairment loss has incurred, the amount of the loss is measured as the difference between the asset’s carrying amount and the present value of estimated future cash flows. The present value of the estimated future cash flows is discounted at the financial assets’ original effective interest rate. If a loan has a variable interest rate, the discount rate for measuring any impairment loss is the current effective interest rate. The carrying amount of the asset is reduced through the use of an allowance account and the amount of the loss is recognized in the income statement. Interest income continues to be accrued on the reduced carrying amount and is accrued using the rate of interest used to discount the future cash flows for the purpose of measuring the impairment loss. The interest income is recorded as part of finance income in the income statement. Loans together with the associated allowance are written off when there is no realistic prospect of future recovery. If, in a subsequent year, the amount of the estimated impairment loss increases or decreases because of an event occurring after the impairment was recognized, the previously recognized impairment loss is increased or reduced by adjusting the allowance account. If a future write-off
Financial liabilities	FINANCIAL LIABILITIES Classification The Group’s financial liabilities include “bank loans”, “lease liabilities”, “recoverable cash advances”, “contingent consideration and other financial liabilities”, “trade payables” and relevant financial liabilities within “Other (non-) The Group classifies and measures its financial liabilities at ‘amortized cost’ using the effective interest method, except “contingent consideration and other financial liabilities” which are classified and measured at ‘fair value through profit or loss’. Initial recognition and measurement All financial liabilities are recognized initially at fair value plus or minus, in the case of a financial liabilities not at fair value through profit or loss, directly attributable transaction costs. Subsequent measurement The subsequent measurement of financial liabilities depends on their classification as explained above. In particular: Contingent consideration The contingent consideration and other financial liabilities are recognized and measured at fair value at the acquisition date. After initial recognition, contingent consideration arrangements that are classified as liabilities are re-measured Details regarding the valuation of the contingent consideration are disclosed in Note 22. Recoverable cash advances Recoverable cash advances granted by the Walloon Region are subsequently measured at amortized cost using the cumulative catch-up Trade payables and other payables After initial recognition, trade payables and other payables are measured at amortized cost using the effective interest method. Loans and borrowings After initial recognition, interest bearing loans and borrowings are subsequently measured at amortized cost using the effective interest rate method. Gains and losses are recognized in the income statement when the liabilities are derecognized. Amortized cost is calculated by taking into account any discount or premium on acquisition and fee or costs that are an integral part of the EIR. The EIR amortization is included in finance expense in the income statement. Derecognition A financial liability is derecognized when the obligation under the liability is discharged or cancelled or expires. When an existing financial liability is replaced by another from the same lender on substantially different terms, or the terms of an existing liability are substantially modified, such an exchange or modification is treated as a derecognition of the original liability and the recognition of a new liability, and the difference in the respective carrying amounts is recognized in the income statement.
Provisions	PROVISIONS Provisions are recognized when the Group has a present obligation (legal or constructive) as a result of a past event, it is probable that an outflow of resources embodying economic benefits will be required to settle the obligation and a reliable estimate can be made of the amount of the obligation. Where the Group expects some or all of a provision to be reimbursed, for example under an insurance contract, the reimbursement is recognized as a separate asset but only when the reimbursement is virtually certain. The expense relating to any provision is presented in the income statement net of any reimbursement. If the effect of the time value of money is material, provisions are discounted using a current pre-tax
Employee benefits	Employee benefits Post-employment plan The Group operates a pension plan which requires defined contributions (DC) to be funded by the Group externally at a third-party insurance company. Under Belgian law, an employer must guarantee a minimum rate of return on the Group’s contributions. Therefore, any pension plan (including DC plans) organized in Belgium is treated as defined benefit plans under IAS 19. At balance sheet date, the minimum rates of return guaranteed by the Group are as follows, in accordance with the law of 18 December 2015: • 1.75% for the employer’s contributions paid as from 1 January 2016 (variable rate based on Governmental bond OLO rates, with a minimum of 1.75% and a maximum of 3.75%); • 3.25% (fixed rate) for the employer’s contributions paid until 31 December 2015. The cost of providing benefits is determined using the projected unit credit (PUC) method, with actuarial valuations being carried out at the end of each annual reporting period, with the assistance of an independent actuarial firm. The liability recognized in the balance sheet in respect of the pension plans is the present value of the defined benefit obligation at the end of the reporting period less the fair value of plan assets. The present value of the defined benefit obligation is determined by discounting the estimated future cash outflows using interest rates of high-quality corporate bonds that are denominated in the currency in which the benefits will be paid, and that have terms to maturity approximating to the terms of the related pension obligation. The current service cost of the defined benefit plan, recognized in the income statement as part of the operating costs, reflects the increase in the defined benefit obligation resulting from employee service in the current year, benefit changes, curtailments and settlements. Past-service costs are recognized immediately in the income statement. The net interest cost is calculated by applying the discount rate to the net balance of the defined benefit obligation and the fair value of plan assets. This cost is included in the operating costs in the income statement. Actuarial gains and losses arising from experience adjustments and changes in actuarial assumptions are charged or credited to other comprehensive income in the period in which they arise. Short-term benefits Short-term employee benefits are those expected to be settled wholly before twelve months after the end of the annual reporting period during which employee services are rendered, but do not include termination benefits such as wages, salaries, profit-sharing and bonuses and non-monetary The undiscounted amount of the benefits expected to be paid in respect of services rendered by employees in an accounting period is recognized in that period. The expected cost of short-term compensated absences is recognized as the employees render services that increase their entitlement or, in the case of non-accumulating Share-based payments Certain employees, managers and members of the Board of Directors of the Group receive remuneration, as compensation for services rendered, in the form of share-based payments which are “equity-settled”. Measurement The cost of equity-settled share-based payments is measured by reference to the fair value at the date on which they are granted. The fair value is determined by using an appropriate pricing model, further details are given in note 16. Recognition The cost of equity-settled share-based payments is recorded as an expense, together with a corresponding increase in equity, over the period in which the service conditions are fulfilled. The cumulative expense recognized for equity-settled transactions at each reporting date until the vesting date reflects the extent to which the vesting period has expired and the Group’s best estimate of the number of equity instruments that will ultimately vest. The estimate of warrants to vest is revised at each reporting date. The change in estimates will be recorded as an expense with a corresponding correction in equity. The expense or credit for a period accounted for in the income statement represents the movement in cumulative expense recognized as of the beginning and end of that period. Modification Where the terms of an equity-settled transaction award are modified, the minimum expense recognized is the expense as if the terms had not been modified, if the original terms of the award were met. An additional expense is recognized for any modification that increases the total fair value of the share-based payment transaction or is otherwise beneficial to the employee as measured at the date of modification. The incremental fair value granted is the difference between the fair value of the modified equity instrument and the original equity instrument, both estimated as at the date of the modification. If the modification occurs during the vesting period, the incremental fair value granted is included in the measurement of the amount recognized for services received over the period from the modification date until the date when the modified equity instruments vest, in addition to the amount based on the grant date fair value of the original equity instruments, which is recognized over the remainder of the original vesting period. If the modification occurs after vesting date, the incremental fair value granted is recognized immediately, or over the vesting period if the employee is required to complete an additional period of service before becoming unconditionally entitled to those modified equity instruments. Cancellation An equity-settled award can be forfeited with the departure of a beneficiary before the end of the vesting period or cancelled and replaced by a new equity settled award. When an equity-settled award is forfeited, the previously recognized expense is offset and credited in the income statement. When an equity-settled award is cancelled, the previously recognized expense is offset and credited in the income statement. However, if a new award is substituted for the cancelled award, and designated as a replacement award on the date that it is granted, the cancelled and new awards are treated as if they were a modification of the original award, as described in the previous paragraph.
Income taxes	INCOME TAXES Tax is recognized in the income statement, except to the extent that it relates to items recognized in other comprehensive income or directly in equity. In this case, the tax is also recognized in other comprehensive income or directly in equity, respectively.
Deferred tax	Deferred tax Deferred tax is provided using the liability method on temporary differences at the reporting date between the tax bases of assets and liabilities and their carrying amounts for financial reporting purposes. Deferred tax liabilities are recognized for all taxable temporary differences, except: • Where the deferred tax liability arises from the initial recognition of goodwill or of an asset or liability in a transaction that is not a business combination and, at the time of the transaction, affects neither the accounting profit nor taxable profit or loss; • In respect of taxable temporary differences associated with investments in subsidiaries, associates and interests in joint ventures, where the timing of the reversal of the temporary differences can be controlled and it is probable that the temporary differences will not reverse in the foreseeable future. Deferred tax assets are recognized for all deductible temporary differences, carry forward of unused tax credits and unused tax losses (except if the deferred tax asset arises from the initial recognition of an asset or liability in a transaction other than a business combination and that, at the time of the transaction affects neither accounting nor taxable profit or loss), to the extent that it is probable that taxable profit will be available against which the deductible temporary differences, and the carry forward of unused tax credits and unused tax losses can be utilized. The carrying amount of deferred tax assets is reviewed at each reporting date and reduced to the extent that it is not probable that sufficient taxable profit will be available to allow all or part of the deferred tax asset to be utilized. Unrecognized deferred tax assets are reassessed at each reporting date and are recognized to the extent that it has become probable that future taxable profits will allow the deferred tax asset to be recovered. Deferred tax assets and liabilities are measured at the tax rates that are expected to apply in the year when the asset is realized or the liability is settled, based on tax rates (and tax laws) that have been enacted or substantively enacted at the reporting date. Deferred tax assets and deferred tax liabilities are offset, if a legally enforceable right exists to set off current tax assets against current income tax liabilities and the deferred taxes relate to income taxes levied by the same taxation authority or either the same taxable entity or different taxable entities where there is an intention to settle the balances on a net basis.
Earnings (loss) per share	EARNINGS (LOSS) PER SHARE The basic net profit/(loss) per share is calculated based on the weighted average number of shares outstanding during the period. The diluted net profit/(loss) per share is calculated based on the weighted average number of shares outstanding including the dilutive effect of potentially dilutive ordinary shares such as warrants and convertible debts. Potentially dilutive ordinary shares should be included in diluted earnings (loss) per share when and only when their conversion to ordinary shares would decrease the net profit per share (or increase net loss per share).

Accounting Principles (Tables)

Accounting Principles (Tables)	12 Months Ended
	Dec. 31, 2019
TextBlockAbstract [Abstract]
Summary of Transition Impact	The transition impact is detailed as follows: (€’000) Operating leases commitments disclosed—31 December 2018 2,912 Future minimum sublease income offset against amount of operating lease commitments previously disclosed [1] 1,078 Adjustment as a result of different treatment of extension options 957 ‘Low-value [2] (137 ) Operating leases commitments as per IFRS 16 scope 4,810 Discounting effect incremental borrowing rate (928 ) IFRS 16 lease liability (discounted) recognized at transition date—1 January 2019 3,882 IFRS 16 lease liability (non-current)—1 3,208 IFRS 16 lease liability (current)—1 January 2019 674 [1] This relates to a real estate property lease in which the Group acts as an intermediate lessor between a head lessor and a sublessee. [2] IFRS 16 scope exemptions, as commented above.

Risk Management (Tables)

Risk Management (Tables)	12 Months Ended
	Dec. 31, 2019
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Foreign Exchange risk Exposure lied on Cash and Short-Term Deposits	At year-end, EUR/USD foreign (loss)/gain exposure +2% +1% -1% -2% 31 December 2019 (€0.1 million) (€0.1 million) +€0.1 million +€0.1 million 31 December 2018 (€0.2 million) (€0.1 million) +€0.1 million +€0.2 million

Operating segment information (

Operating segment information (Tables)	12 Months Ended
	Dec. 31, 2019
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Schedule of Segment Profit by Operating Segment	€’000 For the year ended December 31, 2017 Cardiology Immuno-oncology Corporate Group Total Revenues 35 3,505 3,540 Cost of Sales (515 ) (515 ) Gross Profit 35 2,990 — 3,025 Research & Development expenses (2,881 ) (20,027 ) — (22,908 ) General & Administrative expenses — — (9,310 ) (9,310 ) Other Income and expenses 1,070 151 1,370 2,589 Non-recurring (1,932 ) — (24,341 ) (26,273 ) Operating Profit (Loss) (3,708 ) (16,886 ) (32,281 ) (52,876 ) Net Financial Charges — — (3,521 ) (3,518 ) Profit (Loss) before taxes (3,708 ) (16,886 ) (35,802 ) (56,396 ) Income Taxes — — 1 1 Profit (Loss) for the year 2017 (3,708 ) (16,886 ) (35,801 ) (56,395 ) €’000 For the year ended 31 December 2018, Cardiology Immuno-oncology Corporate Group Total Revenue recognized at a point in time 2,399 — — 2,399 Revenue recognized over time — 716 — 716 Total Revenue 2,399 716 — 3,115 Cost of Sales — — — — Gross Profit 2,399 716 — 3,115 Research & Development expenses (375 ) (23,202 ) — (23,577 ) General & Administrative expenses — — (10,387 ) (10,387 ) Net Other income/(loss) (686 ) (6,765 ) 130 (7,321 ) Operating Profit/(Loss) - EBIT 1,338 (29,251 ) (10,257 ) (38,170 ) Net financial income/(loss) — — 743 743 Profit/(Loss) before taxes 1,338 (29,251 ) (9,515 ) (37,428 ) Income Taxes — — 0 0 Profit/(Loss) for the year 2018 1,338 (29,251 ) (9,514 ) (37,427 ) €’000 For the year ended 31 December 2019, Cardiology Immuno-oncology Corporate Group Total Revenue recognized at a point in time 6 — — 6 Revenue recognized over time — — — — Total Revenue 6 — — 6 Cost of Sales — — — — Gross Profit 6 — — 6 Research & Development expenses (146 ) (25,049 ) — (25,196 ) General & Administrative expenses — — (9,070 ) (9,070 ) Net Other income/(loss) 63 5,228 90 5,381 Operating Profit/(Loss) - EBIT (78 ) (19,821 ) (8,979 ) (28,879 ) Net financial income/(loss) 212 (183 ) 211 239 Profit/(Loss) before taxes 134 (20,005 ) (8,769 ) (28,640 ) Income Taxes — — 8 8 Profit/(Loss) for the year 2019 134 (20,005 ) (8,761 ) (28,632 )

Intangible assets (Tables)

Intangible assets (Tables)	12 Months Ended
	Dec. 31, 2019
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Summary of Intangible Assets	The change in intangible assets is broken down as follows, per class of assets: (€’000) Goodwill In-process Development Patents, Software Total Cost: At 1 January 2018 914 34,854 1,084 13,337 111 50,300 Additions — — — 877 55 932 Currency translation adjustments (31 ) (1,177 ) — — — (1,208 ) Divestiture — — — — (2 ) (2 ) At 31 December 2018 883 33,677 1,084 14,214 164 50,022 Additions — — — 181 46 227 Currency translation adjustments — — — — — — Divestiture — — — (1,493 ) (30 ) (1,523 ) At 31 December 2019 883 33,678 1,084 12,903 179 48,726 Accumulated amortization At 1 January 2018 — — (345 ) (13,337 ) (110 ) (13,792 ) Amortization charge — — (66 ) (1 ) (0 ) (68 ) Divestiture — — — — 2 2 At 31 December 2018 — — (411 ) (13,338 ) (109 ) (13,858 ) Amortization charge — — (66 ) (92 ) (12 ) (169 ) Divestiture — — — 1,493 8 1,501 Impairment (non-recurring — — — — — — At 31 December 2019 — — (477 ) (11,938 ) (112 ) (12,527 ) Net book value Cost 883 33,677 1,084 14,214 164 50,022 Accumulated amortization — — (411 ) (13,338 ) (109 ) (13,858 ) At 31 December 2018 883 33,677 673 876 55 36,164 Cost 883 33,678 1,084 12,903 179 48,726 Accumulated amortization — — (477 ) (11,938 ) (112 ) (12,527 ) At 31 December 2019 883 33,678 607 965 66 36,199
Summary of Probabilities of Success for Products	PoS Phase I Phase I to II Phase II to Phase III to BLA to Cumulative CYAD-01 CYAD-101 100 % 63 % 26 % 45 % 83 % 6.3 %
Summary of Sensitivity Analyses of Recoverable Amount of CGU	The sensitivity analyses are based on a change in an assumption while holding all other assumptions constant. The following table presents the sensitivity analyses of the recoverable amount of the CGU associated to the immuno-oncology operations: Sensitivity analysis Discount rate (WACC) Terminal Revenue Growth rate Impact on model 14.6% 15.3% 16.0% -35% -12% -20% -27% -30% -7% -15% -23% -25% Model -9% -17%

Property, plant and equipment (

Property, plant and equipment (Tables)	12 Months Ended
	Dec. 31, 2019
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Summary of Changes in Carrying Value of Property, Plant and Equipment	(€’000) Property Equipment Furnitures Leasehold Total Cost: At 1 January 2018 — 4,537 445 3,059 8,042 Additions — 564 10 260 833 Reclass BMS SA — (1,032 ) 24 1,007 — Disposals — (123 ) (154 ) (140 ) (417 ) Currency translation adjustments — 1 4 8 13 At 31 December 2018 — 3,947 329 4,195 8,470 Additions 2,810 648 37 167 3,662 Disposals — (496 ) (59 ) (172 ) (728 ) Currency translation adjustments — 0 — 4 4 At 31 December 2019 2,810 4,099 307 4,193 11,409 Accumulated depreciation: At 1 January 2018 — (3,126 ) (229 ) (1,395 ) (4,750 ) Reclass BMS SA — 786 (24 ) (761 ) — Depreciation charge — (529 ) (49 ) (469 ) (1,048 ) Currency translation adjustments — 117 93 133 343 Disposals — 0 (1 ) (1 ) (1 ) At 31 December 2018 — (2,751 ) (211 ) (2,494 ) (5,456 ) Depreciation charge (399 ) (711 ) (54 ) (455 ) (1,619 ) Disposals — 496 59 172 728 Currency translation adjustments — (0 ) — (1 ) (1 ) At 31 December 2019 (399 ) (2,967 ) (205 ) (2,776 ) (6,347 ) Net book value Cost — 3,947 329 4,195 8,471 Accumulated depreciation — (2,751 ) (211 ) (2,494 ) (5,456 ) At 31 December 2018 — 1,196 117 1,701 3,014 Cost 2,810 4,099 307 4,193 11,409 Accumulated depreciation (399 ) (2,967 ) (205 ) (2,776 ) (6,347 ) At 31 December 2019 2,411 1,132 101 1,417 5,061

Other non-current assets (Table

Other non-current assets (Tables)	12 Months Ended
	Dec. 31, 2019
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Summary of Detailed Information About Non-current Trade Receivables	(€’000) As at 31 December, 2019 2018 Non-current 1,955 1,743 Net investment in Lease 477 — Total Non-current 2,432 1,743
Summary of Other Non-current Assets	(€’000) As at 31 December, 2019 2018 R&D Tax credit receivable 3,051 1,472 Total Non-current Grant receivables 3,051 1,472 Deposits 257 215 Total Other non-current 257 215

Trade, Other Receivables and _2

Trade, Other Receivables and Other current assets (Tables)	12 Months Ended
	Dec. 31, 2019
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Summary of Trade, Other Receivables and Other current assets	(€’000) As at 31 December, 2019 2018 Trade receivables 156 277 Advance deposits 149 90 Net Investment in Lease 253 — Other receivables — — Total Trade and Other receivables 558 367 Current Grant receivables (RCAs) 693 — Current Grant receivables (Others) 993 — Total Current Grant receivables 1,686 — Prepaid expenses 647 593 VAT receivable 356 255 Income and other tax receivables 251 737 Total Other current assets 1,253 1,585 Total Trade receivables, advances and other current assets 3,497 1,952

Short Term Investments (Tables)

Short Term Investments (Tables)	12 Months Ended
	Dec. 31, 2019
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Summary of Short Term Investments	(€’000) As at 31 December, 2019 2018 Short-term cash deposits — 8,559 Investment in equity securities 0 639 Total 0 9,197

Cash and Cash Equivalents (Tabl

Cash and Cash Equivalents (Tables)	12 Months Ended
	Dec. 31, 2019
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Summary of Cash and Cash Equivalents	(€‘000) As at 31 December, 2019 2018 Cash at bank and on hand 39,338 40,542 Total 39,338 40,542

Investment in Subsidiaries (Tab

Investment in Subsidiaries (Tables)	12 Months Ended
	Dec. 31, 2019
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Summary of Consolidated Subsidiaries	Name Country of Nature of Business Proportion of shares directly Proportion of Proportion of non-controlling Celyad SA BE Biopharma Parent company Celyad Inc US Biopharma 100% 100 % 0 % CorQuest Medical Inc US Medical Device 100% 100 % 0 % Biological Manufacturing Services SA BE Manufacturing 100% 100 % 0 %

Share Capital (Tables)

Share Capital (Tables)	12 Months Ended
	Dec. 31, 2019
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Summary of Share Capital Issued	The number of shares issued is expressed in units As of 31 December, 2019 2018 Total number of issued and outstanding shares 13,942,344 11,942,344 Total share capital (€‘000) 48,513 41,553
Summary of Share Issuances Occurred Since the Incorporation of the Company	The following share issuances occurred since the incorporation of the Company: Category Transaction date Description # of shares Par value Class A shares 24 July 2007 Company incorporation 409,375 0.15 Class A shares 31 August 2007 Contribution in kind (upfront fee Mayo License) 261,732 36.30 Class B shares 23 December 2008 Capital increase (Round B) 137,150 35.36 Class B shares 23 December 2008 Contribution in kind (Loan B) 67,502 35.36 Class B shares 28 October 2010 Contribution in cash 21,000 22.44 Class B shares 28 October 2010 Contribution in kind (Loan C) 92,068 35.36 Class B shares 28 October 2010 Contribution in kind (Loan D) 57,095 35.36 Class B shares 28 October 2010 Contribution in cash 73,793 35.36 Class B shares 28 October 2010 Exercise of warrants 12,300 22.44 Class B shares 28 October 2010 Contribution in kind (Mayo receivable) 69,455 44.20 Class B shares 28 October 2010 Contribution in cash 9,048 44.20 Class B shares 31 May 2013 Contribution in kind (Loan E) 118,365 38.39 Class B shares 31 May 2013 Contribution in kind (Loan F) 56,936 38.39 Class B shares 31 May 2013 Contribution in kind (Loan G) 654,301 4.52 Class B shares 31 May 2013 Contribution in kind (Loan H) 75,755 30.71 Class B shares 31 May 2013 Contribution in cash 219,016 31.96 Class B shares 4 June 2013 Conversion of warrants 2,409,176 0.01 Ordinary shares 11 June 2013 Conversion of Class A and Class B shares in ordinary shares 4,744,067 — Ordinary shares 5 July 2013 Initial Public Offering 1,381,500 16.65 Ordinary shares 15 July 2013 Exercise of over-allotment option 207,225 16.65 Ordinary shares 31 January 2014 Exercise of warrants issued in September 2008 5,966 22.44 Ordinary shares 31 January 2014 Exercise of warrants issued in May 2010 333 22.44 Ordinary shares 31 January 2014 Exercise of warrants issued in January 2013 120,000 4.52 Ordinary shares 30 April 2014 Exercise of warrants issued in September 2008 2,366 22.44 Ordinary shares 16 June 2014 Capital increase 284,090 44.00 Ordinary shares 30 June 2014 Capital increase 284,090 44.00 Ordinary shares 4 August 2014 Exercise of warrants issued in September 2008 5,000 22.44 Ordinary shares 4 August 2014 Exercise of warrants issued in October 2010 750 35.36 Ordinary shares 3 November 2014 Exercise of warrants issued in September 2008 5,000 22.44 Ordinary shares 21 January 2015 Contribution in kind (Celdara Medical LLC) 93,087 37.08 Ordinary shares 7 February 2015 Exercise of warrant issued in May 2010 333 22.44 Ordinary shares 3 March 2015 Capital increase 713,380 44.50 Ordinary shares 11 May 2015 Exercise of warrant issued in May 2010 500 22.44 Ordinary shares 24 June 2015 Capital increase 1,460,000 60.25 Ordinary shares 4 August 2015 Exercise of warrant issued in May 2010 666 22.44 Ordinary shares 4 August 2015 Exercise of warrant issued in October 2010 5,250 35.36 Ordinary shares 1 February 2017 Exercise of warrant issued in May 2013 207,250 2.64 Ordinary shares 2 May 2017 Exercise of warrant issued in May 2013 4,900 2.64 Ordinary shares 1 August 2017 Exercise of warrant issued in May 2013 7,950 2.64 Ordinary shares 23 August 2017 Contribution in kind (Celdara Medical LLC) 328,275 32.35 Ordinary shares 9 November 2017 Exercise of warrant issued in May 2013 5,000 2.64 Ordinary shares 9 November 2017 Exercise of warrant issued in October 2010 866 35.36 Ordinary shares 7 February 2018 Exercise of warrant issued in May 2013 4,500 2.64 Ordinary shares 22 May 2018 Capital increase 2,070,000 22.29 Ordinary shares 16 Sept 2019 Capital increase 2,000,000 9.08 (€000) Nature of the transactions Share Share Number of shares Balance as of January 1st, 2018 34,337 170,297 9,867,844 Issue of shares related to exercise of warrants 12 — 4,500 Capital increase as a result of the global offering 7,204 35,796 2,070,000 Share Based Payment — 56 — Balance as of December 31, 2018 41,553 206,149 11,942,344 Issue of shares related to exercise of warrants — — — Absorption of accounting losses into Share premium — (172,287 ) — Capital increase as a result of the global offering 6,960 9,488 2,000,000 Share Based Payment — — — Balance as of December 31, 2019 48,513 43,349 13,942,344

Share-Based Payments (Tables)

Share-Based Payments (Tables)	12 Months Ended
	Dec. 31, 2019
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Changes in Number of Warrants Outstanding	Changes in the number of warrants outstanding and their related weighted average exercise prices are as follows: 2019 2018 Weighted average Number of warrants Weighted average Number of warrants Outstanding as of 1 January 30.71 731,229 31.76 674,962 Granted 13.21 610,250 23.09 111,600 Forfeited 8.24 (24,100 ) 28.79 (50,833 ) Exercised — 0 2.64 (4,500 ) Expired 23.60 (24,999 ) — 0 At 31 December 22.56 1,292,380 30.71 731,229
Summary of Warrants Outstanding	Warrants outstanding at the end of the year have the following expiry date and exercise price: Warrant plan issuance Vesting date Expiry date Number of warrants Number of warrants Exercise price 29 October 2010 29 October 2013 29 October 2020 766 766 35.36 06 May 2013 06 May 2016 06 May 2023 2,500 2,500 2.64 05 May 2014 05 May 2017 05 May 2024 35,698 60,697 38.29 05 November 2015 05 November 2018 05 November 2025 250,982 245,982 33.39 08 December 2016 08 December 2019 08 December 2021 42,500 42,500 22.41 29 June 2017 29 June 2020 29 June 2022 285,084 294,484 31.44 26 October 2018 26 October 2021 19 September 2024 401,350 84,300 18.07 25 October 2019 25 October 2022 25 October 2024 273,500 — 8.16 1,292,380 731,229
Summary of Fair Value of Warrants Determined At Grant Date	The fair value of the warrants has been determined at grant date based on the Black-Scholes formula. The variables, used in this model, are: Warrants issued on 29 October 31 January 06 May 05 May 05 Nov. 08 Dec. 29 June 26 October 25 October Total Number of warrants issued 79,500 140,000 266,241 100,000 466,000 100,000 520,000 700,000 939,500 3,311,241 Number of warrants granted 61,050 140,000 253,150 94,400 353,550 45,000 334,400 426,050 273,500 1,981,100 Number of warrants not fully vested as of 31 December 2019 — — — — — 12,500 285,084 401,350 273,500 972,434 Average exercise price (in €) 35.36 4.52 2.64 38.29 33.39 22.41 31.44 18.07 8.16 22.58 Expected share value volatility 35.60 % 35.60 % 39.55 % 67.73 % 60.53 % 61.03 % 60.61 % 58.82 % 59.14 % Risk-free interest rate 3.21 % 2.30 % 2.06 % 1.09 % 0.26 % (0.40 %) (0.23 %) (0.06 %) (0.38 %) Average fair value (in €) 9.00 2.22 12.44 25.22 21.73 11.28 15.65 8.80 3.97 12.34 Weighted average remaining contractual life 0.82 3.08 3.34 4.34 5.84 1.94 2.49 3.82 4.82

Post-Employment Benefits (Table

Post-Employment Benefits (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Summary of Pension Obligations	(€’000) As at 31 December, 2019 2018 Pension obligations 398 131 Total 398 131
Summary of Defined Benefit Amounts Recognized in Balance Sheet	The amounts recognized in the balance sheet are determined as follows: As at 31 December, (€‘000) 2019 2018 Present value of funded obligations 2,330 1,838 Fair value of plan assets (1,932 ) (1,706 ) Deficit of funded plans 398 131 Total deficit of defined benefit pension plans 398 131 Liability in the balance sheet 398 131
Summary of Change in Defined Benefit Liability	The change in the defined benefit liability over the year is as follows: (€‘000) Present value of Fair value of plan Total As at 1 January 2018 1,704 1,499 204 Current service cost 190 0 190 Interest expense/(income) 36 31 5 1,929 1,530 399 Remeasurements - Return on plan assets, excluding amounts included in interest expense/(income) — 9 (9 ) - Actuarial (Gain)/loss due to change in actuarial assumptions (58 ) 0 (58 ) - Actuarial (Gain)/Loss due to experience (3 ) 0 (3 ) (61 ) 9 (70 ) Employer contributions: 0 198 (198 ) Benefits Paid (31 ) (31 ) — At 31 December 2018 1,838 1,707 131 As at 1 January 2019 1,838 1,707 131 Current service cost 193 0 193 Interest expense/(income) 44 31 13 2,076 1,737 339 Remeasurements - Return on plan assets, excluding amounts included in interest expense/(income) — 0 — - Actuarial (Gain)/loss due to change in actuarial assumptions 222 0 222 - Actuarial (Gain)/Loss due to experience 70 0 70 292 — 292 Employer contributions: 0 233 (233 ) Benefits Paid (38 ) (38 ) — At 31 December 2019 2,330 1,932 398
Summary of Income Statement Charge Included in Operating Profit for Post- employment Benefits	The income statement charge included in operating profit for post-employment benefits amount to: (€‘000) 2019 2018 Current service cost 193 190 Interest expense on DBO 44 36 Expected return on plan assets (40 ) (30 ) Net periodic pension cost 198 195
Summary of Remeasurements Included in Other Comprehensive Loss	The re-measurements (€‘000) 2019 2018 Effect of changes in actuarial assumptions 222 (58 ) Effect of experience adjustments 70 (3 ) (Gain)/Loss on assets for the year 8 (9 ) Remeasurement of post-employment benefit obligations 301 (70 )

Other Reserves (Tables)

Other Reserves (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Summary of Information on Other Reserves	(€’000 ) Share based Convertible Currency Total Balance as at 1st January 2018 6,707 16,631 (17 ) 23,322 Vested share-based payments 3,539 0 0 3,539 Currency Translation differences subsidiaries 0 0 (1,194 ) (1,194 ) Balance as at 31 December 2018 10,246 16,631 (1,211 ) 25,667 Vested share-based payments 2,775 0 0 2,775 Currency Translation differences subsidiaries 0 0 (261 ) (261 ) Balance as at 31 December 2019 13,021 16,631 (1,472 ) 28,181

Advances Repayable (Tables)

Advances Repayable (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Summary of Current and Non-current Portion Financial Liabilities	As at December 31, (€‘000) 2019 2018 Non-Current 2,864 1,544 Non-Current 4,139 2,864 Current portion as at 1st January 276 226 Current portion as at 31 December 346 276 Total Recoverable Cash Advances at 1st January 3,140 1,770 Total Recoverable Cash Advances 31 December 4,484 3,140
Summary of Information on Other Outstanding Advances	For further details, reference is made to the table below which shows (i) the year for which amounts under those agreements have been received and initially recognized on the balance sheet for the financial liability and deferred grant income components and (ii) a description of the specific characteristics of those recoverable cash advances including repayment schedule and information on other outstanding advances. In 2020, the Group will be required to make exploitation decisions on the Group’s remaining outstanding RCA related to the CAR-T (in €‘000) Amounts received for the years Amounts to be received As at Id Project Contractual Prior 2018 2019 Cumulated 2020 Status Amount 5160 C-Cure 2,920 2,920 — — 2,920 — Abandoned — 5731 C-Cure 3,400 3,400 — — 3,400 — Abandoned — 5914 C-Cure 700 687 — — 687 — Abandoned 180 5915 C-Cath ez 910 910 — — 910 — Exploitation 530 5951 Industrialization 1,470 866 — — 866 — Abandoned 245 6003 C-Cure 1,729 1,715 — — 1,715 — Abandoned — 6230 C-Cure 1,084 1,084 — — 1,084 — Abandoned — 6363 C-Cure 1,140 1,126 — — 1,126 — Abandoned 1,536 6548 Industrialization 660 541 — — 541 — Abandoned — 6633 C-Cath ez 1,020 1,020 — — 1,020 — Exploitation 245 6646 Proteins 1,200 450 — — 450 — Abandoned 450 7027 C-Cath ez 2,500 2,500 — — 2,500 — Exploitation 375 7246 C-Cure 2,467 2,467 — — 2,467 — Abandoned — 7502 CAR-T 2,000 2,000 — — 2,000 — Exploitation 20 7685 THINK 3,496 873 1,187 1,086 3,146 350 Research — 8087 CYAD01-Deplethink 2,492 — — 623 623 1,869 Research — 8088 CYAD02-Cycle1 3,538 — — 885 885 2,654 Research — 1910028 CwalityCAR 2,102 — — — — 2,102 Research — Total 34,828 22,559 1,187 2,593 26,339 6,975 3,581
Summary of Certain Terms and Conditions for the Recoverable Cash Advances	The table below summarizes, in addition to the specific characteristics described above, certain terms and conditions for the recoverable cash advances: Contract Research phase Percentage Turnover- Turnover-independent reimbursement Interest rate accrual Amounts due in (€’000) 5160 01/05/05-30/04/08 70 % 0.18 % Consolidated with 6363 N/A N/A 5731 01/05/08-31/10/09 70 % 0.18 % Consolidated with 6363 N/A N/A 5914 01/09/08-30/06/11 70 % 5.00 % €30k in 2012 and €70k each year after N/A 10% with a minimum of 100/Y 5915 01/08/08-30/04/11 70 % 5.00 % €40k in 2012 and €70k each year after N/A 10% with a minimum of 100/Y 5951 01/09/08-31/12/14 70 % 5.00 % €100k in 2014 and €150k each year after N/A 10% with a minimum of 200/Y 6003 01/01/09-30/09/11 60 % 0.18 % Consolidated with 6363 N/A N/A 6230 01/01/10-31/03/12 60 % 0.18 % Consolidated with 6363 N/A N/A 6363 01/03/10-30/06/12 60 % 0.18 % From €103k to €514k starting in 2013 until 30% of advance is reached Starting on 01/01/13 N/A 6548 01/01/11-31/03/13 60 % 0.01 % From €15k to €29k starting in 2014 until 30% of advance is reached Starting on 01/10/13 N/A 6633 01/05/11-30/11/12 60 % 0.27 % From €10k to €51k starting in 2013 until 30% of advance is reached Starting on 01/06/13 N/A 6646 01/05/11-30/06/15 60 % 0.01 % From €12k to €60k starting in 2015 until 30% of advance is reached Starting on 01/01/16 N/A 7027 01/11/12-31/10/14 50 % 0.33 % From €25k to €125k starting in 2015 until 30% of advance is reached Starting on 01/01/15 N/A 7246 01/01/14-31/12/16 50 % 0,05 % From €30k to €148k starting in 2017 until 30% of advance is reached. Starting in 2017 N/A 7502 01/12/15-30/11/18 45 % 0.19 % From €20k to €50k starting in 2019 until 30% is reached. Starting 2019 N/A 7685 1/01/17-31/12/19 45 % 0.33 % From €35k to €70k starting in 2020 until 30% is reached. Starting 2020 N/A 8087 01/05/19-31/12/20 45 % 0.22 % From €25k to €75k starting in 2021 until 30% is reached Starting 01/01/21 N/A 8088 01/05/19-31/12/20 45 % 0.21 % From €35k to €106k starting in 2021 until 30% is reached Starting 01/01/21 N/A 1910028 06/06/19-05/05/21 45 % 0.01 % From €21k to €42k starting in 2022 until 30% is reached Starting 01/06/21 N/A

Due Dates of the Financial Li_2

Due Dates of the Financial Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Aggregate Information Material Contractual Obligations and Payments Due	The table below analyses the Group’s non-derivative Financial liabilities reported as at December 31, 2019: (€‘000) Total Less than One to three Three to More than As at 31 December, 2019 Lease liabilities 4,838 1,401 1,952 1,100 385 Bank loan 229 192 37 — — Pension obligations 398 — — — 398 Advances repayable (current and non-current) 4,484 346 490 486 3,163 Total financial liabilities 9,949 1,939 2,479 1,586 3,946 Financial liabilities reported as at December 31, 2018: (€‘000) Total Less than One to five Three to More than As at 31 December, 2018 Finance leases 1,136 484 652 — — Operating leases 2,912 708 942 729 533 Bank loan 510 281 229 — — Pension obligations 131 — — — 131 Advances repayable (current and non-current) 3,140 276 717 560 1,587 Total - material contractual obligations 7,829 1,749 2,540 1,290 2,250

Trade Payables and Other Curr_2

Trade Payables and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Trade Payables and Other Current Liabilities	(€‘000) As at 31 December, 2019 2018 Total Trade payables 6,969 5,916 Other current liabilities Social security 482 314 Payroll accruals and taxes 1,750 1,351 Other current liabilities 1,016 1,024 Total Other current liabilities 3,248 2,690 Total Trade payables and other current liabilities 10,217 8,606

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Summary of Carrying and Fair Values of Financial Instruments that are not Carried at Fair Value	The carrying and fair values of financial instruments that are not carried at fair value in the financial statements was as follows at December 31, for current and comparative year-ends: (€‘000) As of December 31, 2019 Loans and receivables Fair Financial Assets (‘Amortized cost’ category) within: Non-current 2,432 2,432 Other non-current 257 257 Trade receivables and other current assets 558 558 Short-term investments 0 0 Cash and cash equivalents 39,338 39,338 Total 42,586 42,586 For the above-mentioned financial assets, the carrying amount as per December 31, 2019 is a reasonable approximation of their fair value. (€‘000) As of December 31, 2019 Financial liabilities at amortized cost Fair value Financial Liabilities (‘Financial liabilities at amortized cost’ category) within: Bank loans 229 229 Lease liabilities 4,134 4,134 RCAs liability 4,484 4,484 Trade payables and other current liabilities 6,969 6,969 Total 15,759 15,759 For the above-mentioned financial liabilities, the carrying amount as per December 31, 2019 is a reasonable approximation of their fair value. As of December 31, 2018 (€‘000) Loans and receivables Fair Financial Assets (‘Amortized cost’ category) within: Non-current 1,743 1,743 Other non-current 215 215 Trade receivables and other current assets 367 367 Short-term investments 9,197 9,197 Cash and cash equivalents 40,542 40,542 Total 52,065 52,065 For the above-mentioned financial assets, the carrying amount as per December 31, 2018 is a reasonable approximation of their fair value. As of December 31, 2018 (€‘000) Financial liabilities at amortized cost Fair value Financial Liabilities (‘Financial liabilities at amortized cost’ category) within: Bank loans 510 510 Lease liabilities 1,136 1,136 RCAs liability 3,140 3,140 Trade payables and other current liabilities 5,916 5,916 Total 10,702 10,702
Schedule of Financial Assets and Liabilities Measured at Fair Value	Contingent consideration and other financial liabilities are reported at fair value in the statement of financial position using Level 3 fair value measurements for which the Group developed unobservable inputs: (€‘000) Level I Level II Level III Total Assets Investment in equity securities 0 — — 0 Total Assets 0 — — 0 Liabilities — — — — Contingent consideration and other financial liabilities — — 24,754 24,754 Total Liabilities — — 24,754 24,754
Contingent Consideration and Other Financial Liabilities	The change in their balances is detailed as follows: CONTINGENT CONSIDERATION AND OTHER FINANCIAL LIABILITIES ROLL FORWARD (€‘000) For the year ended 2019 2018 Opening balance Contingent consideration at 1 January 20,282 15,549 Milestone payment — — Fair value adjustment (430 ) 4,733 Currency Translation Adjustment — — Closing balance Contingent consideration at 31 December 19,853 20,282 Opening balance Other financial liabilities at 1 January 4,905 4,034 Fair value adjustment (4 ) 871 Closing balance Other financial liabilities at 31 December 4,901 4,905 Total—Contingent consideration and Other financial liabilities at 31 December 24,754 25,187
Sensitivity Analysis Performed on Main Assumptions	A sensitivity analysis has been performed on the key assumptions driving the fair value of the contingent consideration liability. The main drivers are i) the discount rate (WACC), ii) the sales long-term growth rate in the terminal value and iii) the probabilities of success (PoS) for the Group’s product candidates to get commercialized. Discount rate (WACC) 10.6% 12.6% 14.6% 16.6% 18.6% Cont. consideration (€ million) 32.2 28.2 24.8 21.9 19.5 Impact (%) 30 % 14 % — -12 % -21 % Sales long-term growth rate in the terminal value -40% -32.5% -25% -17.5% -10% Cont. consideration (€ million) 23.3 23.9 24.8 26.0 28.0 Impact (%) -6 % -3 % — 5 % 13 % To determine the contingent consideration liability, the Group used the same probabilities of success than for impairment testing purposes (see Note 7): PoS Phase I Phase I to II Phase II to III Phase III to NDA/BLA to Cumulated CYAD-01 CYAD-101 100 % 63 % 26 % 45 % 83 % 6.3 % In order to assess the sensitivity to this driver, the Group applies here an incremental probability factor to the bottom-line cumulative PoS disclosed below: Probabilities of Success -20% -10% PoS model 10% 20% Cont. consideration (€ million) 19.8 22.3 24.8 27.2 29.7 Impact (%) -20 % -10 % — 10 % 20 %

Changes in Liabilities Arisin_2

Changes in Liabilities Arising from Financial Activities (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Summary of Bank Loans Financial Liability Roll Forward	The change in bank loans balances is detailed as follows: BANK LOANS FINANCIAL LIABILITY ROLL FORWARD (€‘000) For the year ended 2019 2018 Opening balance at 1 January 510 536 New bank loans — 220 Installments (281 ) (245 ) Closing balance at 31 December 229 510
Summary of Finance Leases Financial Liability Roll Forward	The change in lease liability balances is detailed as follows: LEASES LIABILITY ROLL FORWARD (€‘000) For the year ended 2019 2018 Opening balance at 1 January 1,136 909 New leases 4,204 730 Installments (1,206 ) (503 ) Closing balance at 31 December 4,134 1,136
Summary of Recoverable Cash Advance Liability Roll Forward	The change in recoverable cash advance liability balances is detailed as follows: RECOVERABLE CASH ADVANCE LIABILITY ROLL FORWARD (€‘000) For the year ended 2019 2018 Opening balance at 1 January 3,140 1,770 Repayments (256 ) (226 ) New Liability component 1,481 598 Remeasurement 120 998 Closing balance at 31 December 4,484 3,140

Revenues and Net Other Income_2

Revenues and Net Other Income and Expenses (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Summary of Revenues	(€‘000) For the year ended 31 December, 2019 2018 2017 Out-licensing — 2.399 3.505 C-CathEZ 6 — 35 Other revenue 0 716 — Total 6 3.115 3.540
Summary of Other Operating Income and Expenses	(€‘000) For the year ended 31 December, 2019 2018 2017 Remeasurement of contingent consideration — 5,604 — Clinical Development milestone payment 36 1,372 — Remeasurement of RCA’s 120 998 — Fair value adjustment on securities — 182 — Other 35 243 41 Total Other Expenses 191 8,399 41 (€‘000) For the year ended 31 December, 2019 2018 2017 Grant income (RCA’s) 1,508 768 824 Grant income (Other) 1,788 — 56 Remeasurement of RCA’s — — 396 Fair value adjustment on securities 182 — — Remeasurement of contingent consideration 433 — 193 R&D tax credit 1,560 310 1,161 Other 102 — — Total Other Income 5,572 1,078 2,630

Operating Expenses (Tables)

Operating Expenses (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Summary of Research and Development Expenses	Research and development expenses The following table is a summary of manufacturing expenses, clinical, quality and regulatory expenses and other research and development expenses, which are aggregated and presented as research and development expenses in the Group’s consolidated financial statements. (€‘000) For the year ended 31 December, 2019 2018 2017 Employee expenses 8,362 7,902 7,007 Travel & Living 486 467 359 Clinical study costs 4,713 4,987 3,901 Preclinical study costs 3,711 2,680 1,820 Process development and scale-up 3,765 2,187 3.319 Consulting fees 675 1,522 1,429 IP filing and maintenance fees 260 474 564 Share-based payments 813 1,264 862 Depreciation 1,444 848 1,488 Rent and utilities 746 668 382 Delivery systems 53 117 430 External collaborations — — 812 Others 168 461 535 Total R&D expenses 25,196 23,577 22,908
Summary of General and Administrative Expenses	General and administrative expenses (€‘000) For the year ended 31 December, 2019 2018 2017 Employee expenses 3,542 3,312 2,630 Share-based payments 1,962 2,331 1,707 Rent & Insurances 625 1,097 1,053 Communication & Marketing 607 676 761 Consulting fees 1,532 2,192 2,227 Travel & Living 331 253 211 Post employment benefits (33 ) (3 ) — Depreciation 345 267 229 Other 159 263 490 Total General and administration 9,070 10,387 9,310
Summary of Non-recurring Operating Income and Expenses	(€‘000) For the year ended 31 December 2019 2018 2017 Amendment of Celdara Medical and Dartmouth College agreements (24,341 ) C-Cure — — (6,045 ) C-Cure — — 5,356 Corquest IP asset impairment expenses — — (1,244 ) Write-off C-Cure — — (1,932 )

Employee Benefit Expenses (Tabl

Employee Benefit Expenses (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Summary of Employee Expenses	A split of the Group’s employees and consultants by main department and geography for the years ended December 31, 2019, 2018 and 2017 was as follows: At December 31, 2019 2018 2017 By function: Clinical & Regulatory, IP, Marketing 26 19 16 Research & Development 33 30 29 Manufacturing /Quality 32 34 26 General Administration 16 13 16 Total 107 96 87 By Geography: Belgium 103 91 83 United States 4 5 4 Total 107 96 87 (€‘000) For the year ended 31 December, 2019 2018 2017 Salaries, wages and fees 6,932 6,439 5,461 Executive Committee compensation 2,993 3,235 2,563 Share-based payments 2,775 3,595 2,569 Social security 1,473 1,301 1,277 Post-employment benefits 215 217 220 Hospitalization insurance 138 118 118 Other benefit expense 119 2 — Total Employee expenses 14,646 14,906 12,207

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Summary of Property Plant And Equipment Owned And Leased Assets	“Property, plant and equipment” comprise owned and leased assets that do not meet the definition of investment property. (€’000) As of December 31, 2019 2018 Property, Plant and Equipment owned (excluding right-of-use 1,713 1,867 Right-of-use 3,348 1,147 Total Property, Plant and Equipment 5,061 3,014
Summary of Lease Liabilities	The statement of financial position shows the following amounts relating to leases for which the Group is a lessee: (€’000) As of December 31, 2019 Property Vehicles Equipment Total Lease assets as per 31 December 2018 — — 1,147 1,147 Right-of-use 2,780 106 72 2,958 Opening balance at 1 January 2019 2,780 106 1,219 4,105 Additions for the period 30 257 — 287 Disposals for the period — — — — Depreciation charge for the period (399 ) (90 ) (555 ) (1,044 ) Closing balance at 31 December 2019 2,411 273 664 3,348
Summary of Lease Expense	The consolidated statements of comprehensive loss show the following amounts relating to leases: (€’000) For the year ended December 31, 2019 Depreciation charge of right-of-use Property 399 Vehicles 90 Equipment 555 Interest on lease liabilities (including in Financial expenses) 1 291 Interest on sublease receivable (including in Financial income) (62 ) Variable lease payments not included in the measurement of lease liabilities — Expenses relating to short-term leases and leases of low-value 182 Total expenses related to leases 1,450 1 Interests on leases are presented as operating cash flow.
Summary of Cash Outflow For Leases	Total cash outflow for leases (€’000) For the year ended 2019 Total cash outflow for leases (including short-term leases and leases of low-value 1,679

Financial Income and Expenses (

Financial Income and Expenses (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Sunmmary of Financial Revenues and Expenses	(€’000) For the year ended 31 December, 2019 2018 2017 Interest on leases 291 18 18 Interest on overdrafts and other finance costs 35 29 36 Interest on RCAs 17 15 90 Foreign Exchange differences — — 4,309 Finance expenses 343 62 4,45 3 Finance income on the net investment in lease 62 — Interest income bank account 30 308 927 Foreign Exchange differences 326 387 — Other financial income 164 109 6 Finance income 582 804 933 Net Financial result 239 743 (3,520 )

Income Tax (Tables)

Income Tax (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Summary of Group Reports Income Taxes in the Income Statement	The Group reports income taxes in the income statement as detailed below: (€‘000) For the year ended 31 December 2019 2018 2017 Current tax (expense) / income 8 0 1 Deferred tax (expense) / income — — — Total income tax expense in profit or loss 8 0 1
Schedule of Reconciliation Between Effective and Theoretical Tax	(€‘000) For the year ended 31 December 2019 2018 2017 Loss before tax (28,640 ) (37,428 ) (56,396 ) — — Permanent differences — — Tax disallowed expenses 967 269 221 Share-based payment 2,775 3,595 2,569 — — Nominal tax rate 29.58 % 29.58 % 33.99 % Tax income at nominal tax rate 1 7,365 9,928 18,220 Deferred Tax assets not recognized (7,357 ) (9,928 ) (18,219 ) — — Effective tax expense 8 0 1 Effective tax rate 0 % 0 % 0 % 1 The difference in foreign tax rate in the US (22.83%) compared to the Belgian rate (29.58%) is not distinctively disclosed in this table due to non-materiality

Deferred Taxes (Tables)

Deferred Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Schedule of Unrecognized Deferred Tax Assets and Liabilities	Unrecognized deferred tax assets and liabilities are detailed below by nature of temporary differences for the current year: (€‘000) For the year ended 31 December 2019 Assets Liabilities Net Intangibles assets — (894 ) (894 ) Tangible assets — (90 ) (90 ) Recoverable cash advances liability 1,056 — 1,056 Contingent consideration liability 6,189 — 6,189 Employee Benefits liability 100 — 100 Other temporary difference — (473 ) (473 ) Tax-losses 55,414 — 55,414 — — — Unrecognized Gross Deferred Tax assets/(liabilities) 62,758 (1,458 ) 61,300 Netting by tax entity (1,365 ) 1,365 — Unrecognized Net Deferred Tax assets/(liabilities) 61,393 (93 ) 61,300 Unrecognized deferred tax assets and liabilities are detailed below by nature of temporary differences for the previous years: For the year ended 31 December 2018 (€‘000) Assets Liabilities Net Intangibles assets 49 — 49 Tangible assets — (154 ) (154 ) Recoverable cash advances liability 633 — 633 Contingent consideration liability 6,297 — 6,297 Employee Benefits liability 33 — 33 Other temporary difference — (436 ) (436 ) Tax-losses 46,858 — 46,858 — — — Unrecognized Gross Deferred Tax assets/(liabilities) 53,869 (590 ) 53,279 Netting by tax entity (437 ) 437 — Unrecognized Net Deferred Tax assets/(liabilities) 53,432 (153 ) 53,279 For the year ended 31 December 2017 (€‘000) Assets Liabilities Net Intangibles assets — (3,974 ) (3,974 ) Tangible assets — (215 ) (215 ) Recoverable cash advances liability 349 — 349 Contingent consideration liability 4,471 — 4,471 Employee Benefits liability 51 — 51 Other temporary difference 5 — 5 Tax-losses 48,152 — 48,152 Unrecognized Gross Deferred Tax assets/(liabilities) 53,028 (4,189 ) 48,839 Netting by tax entity (3,974 ) 3,974 — Unrecognized Net Deferred Tax assets/(liabilities) 49,054 (215 ) 48,839
Schedule of Unrecognised Deferred Tax Asset Balance Roll Forward	The change in the Group’s unrecognized deferred tax asset balance is detailed below: UNRECOGNISED DEFERRED TAX ASSET BALANCE ROLL FORWARD (€‘000) For the year ended 2019 2018 2017 Opening balance at 1 January 53,279 48,839 39,370 Temporary difference creation or reversal (536 ) 5,734 (15,580 ) Change in Tax-losses 8,556 (1,294 ) 44,011 Foreign exchange rate effect — — (113 ) Change in BE tax rate applicable (34% > 25%) — — (14,896 ) Change in US tax rate applicable (35% > 23%) — — (3,953 ) — Closing balance at 31 December 61,300 53,279 48,839

Relationships with Third-Part_2

Relationships with Third-Parties (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Summary of Remuneration of Key Management Informations	Remuneration of key management Key management consists of the members of the Executive Committee and the entities controlled by any of them. As at 31 December, 2019 2018 2017 Number of EMT members 6 7 8 (€’000) For the year ended 31 December 2019 2018 2017 Short term employee benefits [1] 1,112 740 666 Post employee benefits 26 16 14 Share-based compensation 1,005 1,794 1,123 Other employment costs [2] 75 27 30 Management fees 1,789 2,457 1,950 Total benefits 4,006 5,034 3,783 [1] Include salaries, social security, bonuses, lunch vouchers [2] Such as Company cars As at 31 December, 2019 2018 2017 Number of warrants granted 136,500 30,000 179,000 Number of warrants lapsed — — (15,225 ) Cumulative outstanding warrants 295,500 259,000 306,500 Exercised warrants — — 168,000 Outstanding payables (in ‘000€) — 803 461 Transactions with non-executive For the year ended 31 December, (€‘000) 2019 2018 2017 Share-based compensation 430 420 485 Management fees 429 357 387 Total benefits 859 776 872 As at 31 December, 2019 2018 2017 Number of warrants granted 100,000 20,000 60,000 Number of warrants lapsed 5,000 — (2,904 ) Number of exercised warrants — — — Cumulative outstanding warrants 190,000 135,000 115,000 Outstanding payables (in ‘000€) 210 127 194 Shares owned 345,453 345,453 2,512,004

Loss per share (Tables)

Loss per share (Tables)	12 Months Ended
	Dec. 31, 2019
Text block [abstract]
Calculation of Earnings (Loss) Per Share	(€’000) As at 31 December, 2019 2018 2017 Loss of the year attributable to Equity Holders (28,632 ) (37,427 ) (56,395 ) Weighted average number of shares outstanding 12,523,166 11,142,244 9,627,601 Earnings per share (non-fully (2.29 ) (3.36 ) (5.86 ) Outstanding warrants 1,292,380 731,229 674,962

The Company - Additional Inform

The Company - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019Subsidiaries
Disclosure of detailed information about business combination [abstract]
Number of subsidiaries owned by the entity	3

Accounting Principles - Summary

Accounting Principles - Summary of transition impact (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
DisclosureOfSignificantAccountingPoliciesLineItems [Line Items]
Operating leases commitments disclosed—31 December 2018			€ 2,912
Future minimum sublease income offset against amount of operating lease commitments previously disclosed			1,078
Adjustment as a result of different treatment of extension options			957
‘Low-value assets' and ‘short-term' leases			(137)
Operating leases commitments as per IFRS 16 scope	€ 2,967		652
Discounting effect @ incremental borrowing rate			(928)
IFRS 16 lease liability (current)—1 January 2019	€ 1,167		484
IFRS16 [Member]
DisclosureOfSignificantAccountingPoliciesLineItems [Line Items]
Operating leases commitments as per IFRS 16 scope		€ 3,208	€ 4,810
IFRS 16 lease liability (discounted) recognized at transition date—1 January 2019		3,882
IFRS 16 lease liability (current)—1 January 2019		€ 674

Accounting Principles - Additio

Accounting Principles - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019Cash_Generating
Disclosure of significant accounting policies [line items]
Exploitation phase period for recoverable cash advances	10 years
Estimated useful lives of software	10 years
Development costs, capitalization period	17 years
Development costs, amortization period	17 years
Number of cash generating units	2
Non-current financial assets, description	‘Amortized cost’ measurement category refers to loans and receivables which are non-derivative financial assets, with fixed or determinable payments that are not quoted in an active market. They are included in current assets, except for maturities greater than 12 months after the end of the reporting period which are classified as non-current assets. This measurement category comprises “cash and cash equivalents”, “short-term investments”, and relevant financial assets within “(non-) current trade and other receivables” and “other (non-) current assets”
Land and buildings [member]
Disclosure of significant accounting policies [line items]
Depreciation on property, plant and equipment	15 to 20 years
Plant and equipment [member]
Disclosure of significant accounting policies [line items]
Depreciation on property, plant and equipment	5 to 15 years
Laboratory equipment [member]
Disclosure of significant accounting policies [line items]
Depreciation on property, plant and equipment	3 to 5 years
Furniture [member]
Disclosure of significant accounting policies [line items]
Depreciation on property, plant and equipment	3 to 10 years
Top of range [member]
Disclosure of significant accounting policies [line items]
Cash and cash equivalents, original maturity period	1 month
Top of range [member] | Software [member]
Disclosure of significant accounting policies [line items]
Estimated useful lives of software	3 years
Bottom of range [member] | Software [member]
Disclosure of significant accounting policies [line items]
Estimated useful lives of software	5 years

Risk management - Summary of Fo

Risk management - Summary of Foreign Exchange Risk (Detail) - EUR (€) € in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
A2 Percentage Depreciation [member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Unrealized foreign (loss) gain	€ (0.1)	€ (0.2)
A1 Percentage Depreciation [member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Unrealized foreign (loss) gain	(0.1)	(0.1)
A1 Percentage Appreciation [member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Unrealized foreign (loss) gain	0.1	0.1
A2 Percentage Appreciation [member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Unrealized foreign (loss) gain	€ 0.1	€ 0.2

Risk Management - Additional in

Risk Management - Additional information (Detail) - EUR (€) € in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
A1 Percentage Depreciation [member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Unrealized foreign (loss) gain	€ (0.1)	€ (0.1)

Critical Accounting Estimates_2

Critical Accounting Estimates and Judgments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019
Disclosure of changes in accounting estimates [abstract]
Repayable recoverable cash advances percentage	30.00%

Operating Segment Information -

Operating Segment Information - Additional Information (Detail) € in Thousands	12 Months Ended
	Dec. 31, 2019EUR (€)	Dec. 31, 2018EUR (€)	Dec. 31, 2017EUR (€)	Dec. 31, 2015Segment
Disclosure of operating segments [line items]
Number of operating segments | Segment				2
Revenue	€ 6	€ 3,115	€ 3,540
Cardiology [member]
Disclosure of operating segments [line items]
Revenue	€ 6	2,399	€ 35
Cardiology [member] | Mesoblast licence agreement [member]
Disclosure of operating segments [line items]
Revenue		€ 2,400

Operating Segment Information_2

Operating Segment Information - Schedule of Segment Profit by Operating Segment (Detail) - EUR (€) € in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of operating segments [line items]
Revenue recognized at a point in time		€ 6	€ 2,399
Revenue recognized over time			716
Revenue		6	3,115	€ 3,540
Cost of Sales				(515)
Gross Profit		6	3,115	3,025
Research & Development expenses		(25,196)	(23,577)	(22,908)
General & Administrative expenses		(9,070)	(10,387)	(9,310)
Net Other income/(loss)		5,381	(7,321)
Other Income and expenses				2,589
Non-recurring operating (expenses)/income				(26,273)
Operating Loss		(28,879)	(38,170)	(52,876)
Net Financial income/(loss)		239	743	(3,518)
Loss before taxes		(28,640)	(37,428)	(56,396)
Income Taxes		8	0	1
Profit (Loss) for the year	[1]	(28,632)	(37,427)	(56,395)
Cardiology [member]
Disclosure of operating segments [line items]
Revenue recognized at a point in time		6	2,399
Revenue		6	2,399	35
Gross Profit		6	2,399	35
Research & Development expenses		(146)	(375)	(2,881)
Net Other income/(loss)		63	(686)
Other Income and expenses				1,070
Non-recurring operating (expenses)/income				(1,932)
Operating Loss		(78)	1,338	(3,708)
Net Financial income/(loss)		212
Loss before taxes		134	1,338	(3,708)
Profit (Loss) for the year		134	1,338	(3,708)
Immuno-oncology [member]
Disclosure of operating segments [line items]
Revenue recognized over time			716
Revenue			716	3,505
Cost of Sales				(515)
Gross Profit			716	2,990
Research & Development expenses		(25,049)	(23,202)	(20,027)
Net Other income/(loss)		5,228	(6,765)
Other Income and expenses				151
Operating Loss		(19,821)	(29,251)	(16,886)
Net Financial income/(loss)		(183)
Loss before taxes		(20,005)	(29,251)	(16,886)
Profit (Loss) for the year		(20,005)	(29,251)	(16,886)
Corporate [member]
Disclosure of operating segments [line items]
General & Administrative expenses		(9,070)	(10,387)	(9,310)
Net Other income/(loss)		90	130
Other Income and expenses				1,370
Non-recurring operating (expenses)/income				(24,341)
Operating Loss		(8,979)	(10,257)	(32,281)
Net Financial income/(loss)		211	743	(3,521)
Loss before taxes		(8,769)	(9,515)	(35,802)
Income Taxes		8	0	1
Profit (Loss) for the year		€ (8,761)	€ (9,514)	€ (35,801)
[1]	For 2019 and 2018, the Company does not have any non-controlling interests and the losses for the year are fully attributable to owners of the parent.

Intangible Assets - Summary of

Intangible Assets - Summary of Intangible Assets (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure of detailed information about intangible assets [line items]
Beginning balance	€ 36,164
Ending balance	36,199	€ 36,164
Cost [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	50,022	50,300
Additions	227	932
Currency translation adjustments		(1,208)
Divestiture	(1,523)	(2)
Ending balance	48,726	50,022
Accumulated depreciation and amortisation [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance		(13,792)
Amortisation charge	(169)	(68)
Divestiture	1,501	2
Impairment (non-recurring loss)	(12,527)	(13,858)
Ending balance	(12,527)
Goodwill [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	883
Ending balance	883	883
Goodwill [member] | Cost [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	883	914
Currency translation adjustments		(31)
Ending balance	883	883
In-process research and development [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	33,677
Ending balance	33,678	33,677
In-process research and development [member] | Cost [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	33,677	34,854
Currency translation adjustments		(1,177)
Divestiture		0
Ending balance	33,678	33,677
Development cost [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	673
Ending balance	607	673
Development cost [member] | Cost [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	1,084	1,084
Additions		0
Divestiture		0
Ending balance	1,084	1,084
Development cost [member] | Accumulated depreciation and amortisation [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance		(345)
Amortisation charge	(66)	(66)
Impairment (non-recurring loss)	(477)	(411)
Ending balance	(477)
Patents, licences, trademarks [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	876
Ending balance	965	876
Patents, licences, trademarks [member] | Cost [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	14,214	13,337
Additions	181	877
Divestiture	(1,493)	0
Ending balance	12,903	14,214
Patents, licences, trademarks [member] | Accumulated depreciation and amortisation [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance		(13,337)
Amortisation charge	(92)	(1)
Divestiture	1,493
Impairment (non-recurring loss)	(11,938)	(13,338)
Ending balance	(11,938)
Software [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	55
Ending balance	66	55
Software [member] | Cost [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	164	111
Additions	46	55
Divestiture	(30)	(2)
Ending balance	179	164
Software [member] | Accumulated depreciation and amortisation [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance		(110)
Amortisation charge	(12)	0
Divestiture	8	2
Impairment (non-recurring loss)	(112)	€ (109)
Ending balance	€ (112)

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) € in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019EUR (€)	Dec. 31, 2019USD ($)	Oct. 29, 2010EUR (€)	Aug. 31, 2007EUR (€)
Disclosure of detailed information about intangible assets [line items]
Intangible asset amortization period	10 years	10 years
Intellectual property protection period	20 years	20 years
Description of discount rate assumptions	14.6%, in line with industry standards for biotechnological and WACC used by Equity Research companies following the Group	14.6%, in line with industry standards for biotechnological and WACC used by Equity Research companies following the Group
Sales revenue growth rate	25.00%
Milestone Payments | $		$ 0.2
Impairment of intangible assets	€ 35.5
Horizon discovery agreement [member]
Disclosure of detailed information about intangible assets [line items]
CAR-T Therapies acquired	1
CorQuest LLC [member]
Disclosure of detailed information about intangible assets [line items]
Impairment loss on intangible assets	6
Fair value of intellectual rights assets	€ 1.5
Description of key assumptions	The recoverable amount has been calculated based on the fair value less costs to sell model, which requires the use of assumptions. The calculations use cash flow projections based on 11-year period business plan based on probability of success of CYAD-01 and CYAD-101 product candidates as well as extrapolations of projected cash flows resulting from the future expected sales associated with CYAD-01 and CYAD-101. CGU recoverable value, determined accordingly, exceeds its carrying amount.	The recoverable amount has been calculated based on the fair value less costs to sell model, which requires the use of assumptions. The calculations use cash flow projections based on 11-year period business plan based on probability of success of CYAD-01 and CYAD-101 product candidates as well as extrapolations of projected cash flows resulting from the future expected sales associated with CYAD-01 and CYAD-101. CGU recoverable value, determined accordingly, exceeds its carrying amount.
Period over which management has projected cash flows	11 year	11 year
Impairment loss on intangible assets and goodwill | $		$ 0
C-Cure [member]
Disclosure of detailed information about intangible assets [line items]
Percentage of impairment allowances carry forward	100.00%
HeartXs assets [member]
Disclosure of detailed information about intangible assets [line items]
Percentage of impairment allowances carry forward	100.00%
Licences [member]
Disclosure of detailed information about intangible assets [line items]
Intangible asset amortization period	20 years	20 years
Intangible assets			€ 2.3	€ 9.5
Patents 1 [member] | CorQuest LLC [member]
Disclosure of detailed information about intangible assets [line items]
Impairment loss on intangible assets	€ 1.2
Patents 1 [member] | CorQuest LLC [member]
Disclosure of detailed information about intangible assets [line items]
Intangible asset amortization period	18 years	18 years
Bottom of range [member] | Software [member]
Disclosure of detailed information about intangible assets [line items]
Intangible asset amortization period	5 years	5 years
Top of range [member] | Software [member]
Disclosure of detailed information about intangible assets [line items]
Intangible asset amortization period	3 years	3 years

Intangible Assets - Summary o_2

Intangible Assets - Summary of Probabilities of Success for Products (Detail)	12 Months Ended
	Dec. 31, 2019
Disclosure of detailed information about intangible assets [line items]
Probablity of success percentage	6.30%
CYAD 01 [member]
Disclosure of detailed information about intangible assets [line items]
Probablity of success percentage	6.30%
Phase I [member]
Disclosure of detailed information about intangible assets [line items]
Probablity of success percentage	100.00%
Phase I [member] | CYAD 01 [member]
Disclosure of detailed information about intangible assets [line items]
Probablity of success percentage	100.00%
Phase I to II [member]
Disclosure of detailed information about intangible assets [line items]
Probablity of success percentage	63.00%
Phase I to II [member] | CYAD 01 [member]
Disclosure of detailed information about intangible assets [line items]
Probablity of success percentage	63.00%
Phase II to III [member]
Disclosure of detailed information about intangible assets [line items]
Probablity of success percentage	26.00%
Phase II to III [member] | CYAD 01 [member]
Disclosure of detailed information about intangible assets [line items]
Probablity of success percentage	26.00%
Phase III to BLA [member]
Disclosure of detailed information about intangible assets [line items]
Probablity of success percentage	45.00%
Phase III to BLA [member] | CYAD 01 [member]
Disclosure of detailed information about intangible assets [line items]
Probablity of success percentage	45.00%
BLA to approval [member]
Disclosure of detailed information about intangible assets [line items]
Probablity of success percentage	83.00%
BLA to approval [member] | CYAD 01 [member]
Disclosure of detailed information about intangible assets [line items]
Probablity of success percentage	83.00%

Intangible Assets - Summary o_3

Intangible Assets - Summary of Sensitivity Analyses of Recoverable Amount of CGU (Detail)	12 Months Ended
	Dec. 31, 2019
Impact of -35% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	35.00%
Impact of -30% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	30.00%
Impact of -25% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	25.00%
Discount rate at 14.6% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	14.60%
Discount rate at 14.6% [member] | Impact of -35% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	12.00%
Discount rate at 14.6% [member] | Impact of -30% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	7.00%
Discount rate at 15.40% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	15.30%
Discount rate at 15.40% [member] | Impact of -35% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	20.00%
Discount rate at 15.40% [member] | Impact of -30% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	15.00%
Discount rate at 15.40% [member] | Impact of -25% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	9.00%
Discount rate at 16.0% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	16.00%
Discount rate at 16.0% [member] | Impact of -35% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	27.00%
Discount rate at 16.0% [member] | Impact of -30% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	23.00%
Discount rate at 16.0% [member] | Impact of -25% [member]
Disclosure of detailed information about intangible assets [line items]
Terminal Revenue Growth rate	17.00%

Property, Plant and Equipment -

Property, Plant and Equipment - Summary of Changes in Carrying Value of Property, Plant and Equipment (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	€ 3,014
Ending balance	5,061	€ 3,014
Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	8,470	8,042
Additions	3,662	833
Disposals	(728)	(417)
Currency translation adjustments	4	13
Ending balance	11,409	8,470
Accumulated depreciation [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	(5,456)	(4,750)
Depreciation charge	(1,619)	(1,048)
Disposals	728	(1)
Currency translation adjustments	(1)	343
Ending balance	(6,347)	(5,456)
Property [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Additions	2,810
Ending balance	2,411
Property [Member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Ending balance	2,810
Property [Member] | Accumulated depreciation [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Depreciation charge	(399)
Ending balance	(399)
Equipment [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	1,196
Ending balance	1,132	1,196
Equipment [Member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	3,947	4,537
Additions	648	564
Reclass BMS SA		(1,032)
Disposals	(496)	(123)
Currency translation adjustments	0	1
Ending balance	4,099	3,947
Equipment [Member] | Accumulated depreciation [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	(2,751)	(3,126)
Reclass BMS SA		786
Depreciation charge	(711)	(529)
Disposals	496	0
Currency translation adjustments	0	117
Ending balance	(2,967)	(2,751)
Furniture [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	117
Ending balance	101	117
Furniture [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	329	445
Additions	37	10
Reclass BMS SA		24
Disposals	(59)	(154)
Currency translation adjustments		4
Ending balance	307	329
Furniture [member] | Accumulated depreciation [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	(211)	(229)
Reclass BMS SA		(24)
Depreciation charge	(54)	(49)
Disposals	59	(1)
Currency translation adjustments		93
Ending balance	(205)	(211)
Leasehold improvements [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	1,701
Ending balance	1,417	1,701
Leasehold improvements [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	4,195	3,059
Additions	167	260
Reclass BMS SA		1,007
Disposals	(172)	(140)
Currency translation adjustments	4	8
Ending balance	4,193	4,195
Leasehold improvements [member] | Accumulated depreciation [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	(2,494)	(1,395)
Reclass BMS SA		(761)
Depreciation charge	(455)	(469)
Disposals	172	(1)
Currency translation adjustments	(1)	133
Ending balance	€ (2,776)	€ (2,494)

Property, Plant and Equipment_2

Property, Plant and Equipment - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019
Disclosure of detailed information about property, plant and equipment [abstract]
Finance leases maturity term	3 years

Other Non-current Assets - Summ

Other Non-current Assets - Summary of Detailed Information About Non-current Trade Receivables (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018
Disclosure of other non current assets [line items]
Non-current trade receivables Mesoblast license agreement	€ 2,432	€ 1,743
Net investment in Lease	477
Mesoblast licence agreement [member]
Disclosure of other non current assets [line items]
Non-current trade receivables Mesoblast license agreement	€ 1,955	€ 1,743

Other Non-current Assets - Su_2

Other Non-current Assets - Summary of Non-current Financial Assets (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of Other Noncurrent Assets [abstract]
R&D Tax credit receivable	€ 3,051	€ 1,472	€ 1,200
Total Non-current Grant receivables	3,051	1,472
Deposits	257	215
Total Other non-current assets	€ 257	€ 215

Other Non-current Assets - Addi

Other Non-current Assets - Additional Information (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of Other Noncurrent Assets [abstract]
R&D Tax credit receivable	€ 3,051	€ 1,472	€ 1,200

Trade, Other Receivables and _3

Trade, Other Receivables and Other current assets - Summary of Trade Receivables and Other Current Assets (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018
Disclosure of trade and other receivables [abstract]
Trade receivables	€ 156	€ 277
Advance deposits	149	90
Net Investment in Lease	253
Total Trade and Other receivables	558	367
Current Grant receivables (RCAs)	693
Current Grant receivables (Others)	993
Total Current Grant receivables	1,686
Prepaid expenses	647	593
VAT receivable	356	255
Income and other tax receivables	251	737
Total Other current assets	1,253	1,585
Total Trade receivables, advances and other current assets	€ 3,497	€ 1,952

Trade, Other Receivables and _4

Trade, Other Receivables and Other Current Assets - Additional Information (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of trade and other receivables [line items]
Trade and other receivables overdue	€ 0
Impairment loss	0
Recoverable Cash Advances	4,484	€ 3,140	€ 1,770
Short Term Deposits Interests Decrease Due To Witholding Tax		200
Short Term Deposits Interests Recovering From Withholding Tax		300
Walloon Region [Member]
Disclosure of trade and other receivables [line items]
Grant Receivables Due To Related Parties	1,700
Recoverable Cash Advances	700
Ono non clinical supply services agreement [member]
Disclosure of trade and other receivables [line items]
Increase in Trade receivables		€ 200
CYAD 02 [Member]
Disclosure of trade and other receivables [line items]
Adjustments For Increase Decrease In Advance Deposits	100
Foreign currencies [member]
Disclosure of trade and other receivables [line items]
Carrying amounts for trade and other receivables denominated in foreign currencies	€ 0

Short Term Investments - Summar

Short Term Investments - Summary of Short Term Investments (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018
Short term investments1 [abstract]
Short-term cash deposits		€ 8,559
Investment in equity securities	€ 0	639
Total	€ 0	€ 9,197

Cash and Cash Equivalents - Sum

Cash and Cash Equivalents - Summary of Cash and Cash Equivalents (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash and cash equivalents [abstract]
Cash at bank and on hand	€ 39,338	€ 40,542
Total	€ 39,338	€ 40,542	€ 23,253	€ 48,357

Investment in Subsidiaries - Su

Investment in Subsidiaries - Summary of Consolidated Subsidiaries (Detail)	12 Months Ended
	Dec. 31, 2019
Celyad SA [Member] | Belgium [member]
Disclosure of subsidiaries [line items]
Name	Celyad SA
Country of Incorporation and Place of Business	BE
Nature of Business	Biopharma
Celyad Inc [member] | USA [member]
Disclosure of subsidiaries [line items]
Name	Celyad Inc
Country of Incorporation and Place of Business	US
Nature of Business	Biopharma
Proportion of Propo ordinary ordina shares directly held by held by parent (%)	100.00%
Proportion of ordinary shares held by the group (%)	100.00%
Proportion of ordinary shares held by non-controlling interests (%)	0.00%
Corquest Medical Inc [member] | USA [member]
Disclosure of subsidiaries [line items]
Name	CorQuest Medical Inc
Country of Incorporation and Place of Business	US
Nature of Business	Medical Device
Proportion of Propo ordinary ordina shares directly held by held by parent (%)	100.00%
Proportion of ordinary shares held by the group (%)	100.00%
Proportion of ordinary shares held by non-controlling interests (%)	0.00%
Biological Manufacturing Services SA [member] | Belgium [member]
Disclosure of subsidiaries [line items]
Name	Biological Manufacturing Services SA
Country of Incorporation and Place of Business	BE
Nature of Business	Manufacturing
Proportion of Propo ordinary ordina shares directly held by held by parent (%)	100.00%
Proportion of ordinary shares held by the group (%)	100.00%
Proportion of ordinary shares held by non-controlling interests (%)	0.00%

Share Capital Issued - Summary

Share Capital Issued - Summary of Share Capital Issued (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018
Disclosure of classes of share capital [abstract]
Total number of issued and outstanding shares	13,942,344	11,942,344
Total share capital	€ 48,513	€ 41,553

Share Capital Issued - Addition

Share Capital Issued - Additional Information (Detail) € / shares in Units, $ in Millions

Oct. 25, 2019

Oct. 26, 2018

May 18, 2018EUR (€)

May 18, 2018USD ($)

Jun. 29, 2017

Dec. 08, 2016

Nov. 05, 2015

May 05, 2014

Jul. 15, 2013EUR (€)shares

Jun. 11, 2013EUR (€)

May 31, 2013EUR (€)

May 06, 2013

May 05, 2011EUR (€)

Oct. 29, 2010EUR (€)€ / sharesshares

Oct. 14, 2010EUR (€)€ / sharesshares

Dec. 23, 2008EUR (€)shares

Aug. 31, 2007EUR (€)shares

Sep. 30, 2019EUR (€)

Sep. 30, 2019USD ($)

Aug. 31, 2017EUR (€)€ / sharesshares

Jun. 30, 2015EUR (€)shares

Mar. 31, 2015EUR (€)shares

Jan. 31, 2015EUR (€)shares

Jun. 30, 2014EUR (€)shares

Dec. 31, 2019EUR (€)€ / sharesshares

Dec. 31, 2018EUR (€)

Dec. 31, 2017EUR (€)shares

Dec. 31, 2015EUR (€)shares

Dec. 31, 2014EUR (€)shares

May 31, 2019EUR (€)

Jul. 05, 2013EUR (€)€ / sharesshares

Jul. 24, 2007EUR (€)shares

Disclosure of classes of share capital [line items]

Issued capital

€ 48,513,000

€ 41,553,000

Number of ordinary shares | shares

13,942,344

Common stock , par value | € / shares

€ 3.48

Date of incorporation

Jul. 24, 2007

Share capital

€ 62,500

Proceeds from capital increase

€ 12,100,809

Warrants exercised | shares

225,966

6,749

139,415

Increase in capital

€ 18,925,474

€ 25,000,000

€ 625,000

Convertible loans converted to shares, amount

€ 28,645,000

Increase in capital and issue premium by contribution in cash

7,000,000

Preferred shares conversion ratio

100.00%

Proceeds from issuing shares

€ 16,448,000

€ 43,011,000

€ 625,000

Cost related to capital increase

€ 2,800,000

Description of authorization invested in board of directors

On June 11, 2013, the Extraordinary General Shareholders’ Meeting of Celyad SA authorized the Board of Directors to increase the share capital of the Company, in one or several times, and under certain conditions set forth in extenso in the articles of association. This authorization is valid for a period of five years starting on July 26, 2013 and until July 26, 2018. The Board of Directors may increase the share capital of the Company within the framework of the authorized capital for an amo

Expected increase in capital

€ 21,413,000

Shares issued related to exercise of warrants | shares

225,966

6,749

139,415

Warrants exercise periods

5 years

5 years

5 years

5 years

10 years

10 years

10 years

10 years

Over four different exercise periods

Over three different exercise periods

Over four different exercise periods

Issue Of Equity

€ 10,620,000

Decrease In Share Premium

€ 172,300,000

Oncyte LLC

Disclosure of classes of share capital [line items]

Shares issued | shares

93,087

Increase in capital

€ 3,452,000

Initial public offering [member]

Disclosure of classes of share capital [line items]

Issued capital

€ 23,002,000

Common stock , par value | € / shares

€ 16.65

Shares issued | shares

1,460,000

1,381,500

Increase in capital

€ 87,965,000

Proceeds from issuing shares

€ 26,452,000

Over allotment option [member]

Disclosure of classes of share capital [line items]

Shares issued | shares

207,225

Proceeds from issuing shares

€ 3,450,000

Share capital [member]

Disclosure of classes of share capital [line items]

Increase in capital

€ 23,000

€ 488,000

Convertible loans converted to shares, amount

5,026,000

Issue Of Equity

1,141,000

Share premium [member]

Disclosure of classes of share capital [line items]

Increase in capital

€ 196,000

€ 500,000

Convertible loans converted to shares, amount

6,988,000

Issue Of Equity

€ 9,479,000

Private placement [member]

Disclosure of classes of share capital [line items]

Shares issued | shares

713,380

Increase in capital

€ 31,745,000

Other reserves [member]

Disclosure of classes of share capital [line items]

Convertible loans converted to shares, amount

€ 16,613,000

Conversion of Loan D [member]

Disclosure of classes of share capital [line items]

Nominal amount

€ 2,010,000,000

Round B Investors [member]

Disclosure of classes of share capital [line items]

Shares authorized | shares

875,759

Round B Investors [member] | Convertible loan [member]

Disclosure of classes of share capital [line items]

Capital contribution

€ 2,387,049

Round B Investors [member] | Cash 1 [member]

Disclosure of classes of share capital [line items]

Capital contribution

4,849,624

Round B Investors [member] | Uncalled Cash [member]

Disclosure of classes of share capital [line items]

Capital contribution

€ 1,949,624

Celdara Medical [member]

Disclosure of classes of share capital [line items]

Common stock , par value | € / shares

€ 32.35

Shares issued | shares

328,275

Proceeds from issuing shares

€ 43,000,000

€ 16,400,000

Description of share price calculation

Average market price

Issue Of Equity

€ 46,100,000

$ 54.4

€ 18,200,000

$ 20

Celdara Medical [member] | Share capital [member]

Disclosure of classes of share capital [line items]

Increase in capital

€ 1,141,000

Celdara Medical [member] | Share premium [member]

Disclosure of classes of share capital [line items]

Increase in capital

€ 9,479,000

Mayo Clinic [member]

Disclosure of classes of share capital [line items]

Contribution in kind of the upfront fee that was due upon execution of the Mayo Licence

€ 9,500,000

Medisun International Limited [member]

Disclosure of classes of share capital [line items]

Shares subscribed | shares

568,180

Class A shares [member]

Disclosure of classes of share capital [line items]

Shares issued | shares

409,375

Class A shares [member] | Round B Investors [member]

Disclosure of classes of share capital [line items]

Shares authorized | shares

671,107

Class A shares [member] | Mayo Clinic [member]

Disclosure of classes of share capital [line items]

Shares issued | shares

261,732

Class B shares [member] | Conversion of Loan D [member]

Disclosure of classes of share capital [line items]

Shares issued | shares

57,095

Capital contribution

€ 2,018,879.20

Share conversion price per share | € / shares

€ 35.36

Class B shares [member] | Conversion of Loan C [member]

Disclosure of classes of share capital [line items]

Shares issued | shares

92,068

Capital contribution

€ 3,255,524.48

Share conversion price per share | € / shares

€ 35.36

Class B shares [member] | Round B Investors [member]

Disclosure of classes of share capital [line items]

Shares issued | shares

204,652

Shares authorized | shares

204,652

Class B shares [member] | Existing investor [member]

Disclosure of classes of share capital [line items]

Common stock , par value | € / shares

€ 35.36

Shares issued | shares

73,793

Capital contribution

€ 2,609,320.48

Class B shares [member] | New Investor [member]

Disclosure of classes of share capital [line items]

Common stock , par value | € / shares

€ 44.20

Shares issued | shares

9,048

Capital contribution

€ 399,921.60

Class B shares [member] | Round C Investors [member]

Disclosure of classes of share capital [line items]

Shares issued | shares

12,300

Class B shares [member] | Mayo Clinic [member]

Disclosure of classes of share capital [line items]

Common stock , par value | € / shares

€ 44.20

Shares issued | shares

69,455

Contribution in kind

€ 3,069,911

Class B shares [member]

Disclosure of classes of share capital [line items]

Common stock , par value | € / shares

€ 35.36

Shares issued | shares

67,502

Class B shares [member] | Existing investor [member]

Disclosure of classes of share capital [line items]

Common stock , par value | € / shares

€ 22.44

Shares issued | shares

21,000

Capital contribution

€ 471,240

Warrant A [member] | Round C Investors [member]

Disclosure of classes of share capital [line items]

Warrants exercised | shares

12,300

Proceeds from exercise of warrants

€ 276,012

Warrants exercise price | € / shares

€ 22.44

Share Capital Issued - Summar_2

Share Capital Issued - Summary of Share Issuances Occurred Since the Incorporation of the Company (Detail) - EUR (€) € / shares in Units, € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of classes of share capital [line items]
Par value	€ 3.48
Beginning balance	€ 55,589	€ 47,535	€ 90,885
Issue of shares related to exercise of warrants		12	625
Share-based payments	2,775	3,595	2,569
Ending balance	45,619	55,589	47,535
Share capital [member]
Disclosure of classes of share capital [line items]
Beginning balance	41,553	34,337	32,571
Issue of shares related to exercise of warrants		12	625
Capital increase as a result of the global offering	6,960	7,204
Ending balance	48,513	41,553	34,337
Share premium [member]
Disclosure of classes of share capital [line items]
Beginning balance	206,149	170,297	158,010
Capital increase as a result of the global offering	9,488	35,796
Absorption of accounting losses into Share premium	172,287
Share-based payments		56	2,808
Ending balance	43,349	206,149	170,297
Number of shares [member]
Disclosure of classes of share capital [line items]
Beginning balance	11,942,344	9,867,844
Issue of shares related to exercise of warrants		4,500
Capital increase as a result of the global offering	2,000,000	2,070,000
Ending balance	€ 13,942,344	€ 11,942,344	€ 9,867,844
Class A shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Jul. 24, 2007
Description	Company incorporation
# of shares	409,375
Par value	€ 0.15
Class A shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Aug. 31, 2007
Description	Contribution in kind (upfront fee Mayo License)
# of shares	261,732
Par value	€ 36.30
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Dec. 23, 2008
Description	Capital increase (Round B)
# of shares	137,150
Par value	€ 35.36
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Dec. 23, 2008
Description	Contribution in kind (Loan B)
# of shares	67,502
Par value	€ 35.36
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Oct. 28, 2010
Description	Contribution in cash
# of shares	21,000
Par value	€ 22.44
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Oct. 28, 2010
Description	Contribution in kind (Loan C)
# of shares	92,068
Par value	€ 35.36
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Oct. 28, 2010
Description	Contribution in kind (Loan D)
# of shares	57,095
Par value	€ 35.36
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Oct. 28, 2010
Description	Contribution in cash
# of shares	73,793
Par value	€ 35.36
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Oct. 28, 2010
Description	Exercise of warrants
# of shares	12,300
Par value	€ 22.44
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Oct. 28, 2010
Description	Contribution in kind (Mayo receivable)
# of shares	69,455
Par value	€ 44.20
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Oct. 28, 2010
Description	Contribution in cash
# of shares	9,048
Par value	€ 44.20
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	May 31, 2013
Description	Contribution in kind (Loan E)
# of shares	118,365
Par value	€ 38.39
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	May 31, 2013
Description	Contribution in kind (Loan F)
# of shares	56,936
Par value	€ 38.39
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	May 31, 2013
Description	Contribution in kind (Loan G)
# of shares	654,301
Par value	€ 4.52
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	May 31, 2013
Description	Contribution in kind (Loan H)
# of shares	75,755
Par value	€ 30.71
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	May 31, 2013
Description	Contribution in cash
# of shares	219,016
Par value	€ 31.96
Class B shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Jun. 4, 2013
Description	Conversion of warrants
# of shares	2,409,176
Par value	€ 0.01
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Jun. 11, 2013
Description	Conversion of Class A and Class B shares in ordinary shares
# of shares	4,744,067
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Jul. 5, 2013
Description	Initial Public Offering
# of shares	1,381,500
Par value	€ 16.65
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Jul. 15, 2013
Description	Exercise of over-allotment option
# of shares	207,225
Par value	€ 16.65
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Jan. 31, 2014
Description	Exercise of warrants issued in September 2008
# of shares	5,966
Par value	€ 22.44
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Jan. 31, 2014
Description	Exercise of warrants issued in May 2010
# of shares	333
Par value	€ 22.44
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Jan. 31, 2014
Description	Exercise of warrants issued in January 2013
# of shares	120,000
Par value	€ 4.52
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Apr. 30, 2014
Description	Exercise of warrants issued in September 2008
# of shares	2,366
Par value	€ 22.44
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Jun. 16, 2014
Description	Capital increase
# of shares	284,090
Par value	€ 44
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Jun. 30, 2014
Description	Capital increase
# of shares	284,090
Par value	€ 44
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Aug. 4, 2014
Description	Exercise of warrants issued in September 2008
# of shares	5,000
Par value	€ 22.44
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Aug. 4, 2014
Description	Exercise of warrants issued in October 2010
# of shares	750
Par value	€ 35.36
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Nov. 3, 2014
Description	Exercise of warrants issued in September 2008
# of shares	5,000
Par value	€ 22.44
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Jan. 21, 2015
Description	Contribution in kind (Celdara Medical LLC)
# of shares	93,087
Par value	€ 37.08
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Feb. 7, 2015
Description	Exercise of warrant issued in May 2010
# of shares	333
Par value	€ 22.44
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Mar. 3, 2015
Description	Capital increase
# of shares	713,380
Par value	€ 44.50
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	May 11, 2015
Description	Exercise of warrant issued in May 2010
# of shares	500
Par value	€ 22.44
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Jun. 24, 2015
Description	Capital increase
# of shares	1,460,000
Par value	€ 60.25
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Aug. 4, 2015
Description	Exercise of warrant issued in May 2010
# of shares	666
Par value	€ 22.44
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Transaction date	Aug. 4, 2015
Description	Exercise of warrant issued in October 2010
# of shares	5,250
Par value	€ 35.36
Ordinary shares twenty [member]
Disclosure of classes of share capital [line items]
Transaction date	Feb. 1, 2017
Description	Exercise of warrant issued in May 2013
# of shares	207,250
Par value	€ 2.64
Ordinary shares twenty one [member]
Disclosure of classes of share capital [line items]
Transaction date	May 2, 2017
Description	Exercise of warrant issued in May 2013
# of shares	4,900
Par value	€ 2.64
Ordinary shares twenty two [member]
Disclosure of classes of share capital [line items]
Transaction date	Aug. 1, 2017
Description	Exercise of warrant issued in May 2013
# of shares	7,950
Par value	€ 2.64
Ordinary shares twenty three [member]
Disclosure of classes of share capital [line items]
Transaction date	Aug. 23, 2017
Description	Contribution in kind (Celdara Medical LLC)
# of shares	328,275
Par value	€ 32.35
Ordinary shares twenty four [member]
Disclosure of classes of share capital [line items]
Transaction date	Nov. 9, 2017
Description	Exercise of warrant issued in May 2013
# of shares	5,000
Par value	€ 2.64
Ordinary shares twenty five [member]
Disclosure of classes of share capital [line items]
Transaction date	Nov. 9, 2017
Description	Exercise of warrant issued in October 2010
# of shares	866
Par value	€ 35.36
Ordinary shares twenty six [member]
Disclosure of classes of share capital [line items]
Transaction date	Feb. 7, 2018
Description	Exercise of warrant issued in May 2013
# of shares	4,500
Par value	€ 2.64
Ordinary shares twenty seven [member]
Disclosure of classes of share capital [line items]
Transaction date	May 22, 2018
Description	Capital increase
# of shares	2,070,000
Par value	€ 22.29
Ordinary SharesTwenty Eight Member [Member]
Disclosure of classes of share capital [line items]
Transaction date	Sep. 16, 2019
Description	Capital increase
# of shares	2,000,000
Par value	€ 9.08

Share-based Payments - Changes

Share-based Payments - Changes in Number of Warrants Outstanding (Detail)	Oct. 25, 2019Warrant€ / shares	Oct. 26, 2018Warrant	Jun. 29, 2017Warrant	Nov. 05, 2015Warrant	May 05, 2014Warrant	May 06, 2013Warrant€ / shares	Oct. 29, 2010Warrant€ / shares	Dec. 31, 2019Warrant€ / shares	Dec. 31, 2018Warrant€ / shares
Disclosure of terms and conditions of share-based payment arrangement [abstract]
Weighted average exercise price, outstanding, beginning of period | € / shares								€ 30.71	€ 31.76
Weighted average exercise price, granted | € / shares								13.21	23.09
Weighted average exercise price, forfeited | € / shares								8.24	28.79
Weighted average exercise price, exercised | € / shares									2.64
Weighted average exercise price, expired | € / shares								23.60
Weighted average exercise price outstanding, end of period | € / shares	€ 8.16					€ 2.64	€ 35.36	€ 22.56	€ 30.71
Number of warrants outstanding, beginning of period | Warrant								731,229	674,962
Number of warrants, granted | Warrant	273,500	426,050	334,400	353,550	94,400	253,150	61,050	610,250	111,600
Number of warrants, forfeited | Warrant								(24,100)	(50,833)
Number of warrants, exercised | Warrant					(100,000)	(253,150)	(61,050)	0	(4,500)
Number of warrants, expired | Warrant								(24,999)	0
Number of warrants outstanding, end of period | Warrant	273,500	401,350	285,084	250,982	35,698	2,500	766	1,292,380	731,229

Share-based Payments - Addition

Share-based Payments - Additional Information (Detail) € / shares in Units, € in Millions	Oct. 25, 2019Warrant€ / sharesshares	Oct. 26, 2018Warrant€ / sharesshares	Jun. 29, 2017Warrant€ / sharesshares	Dec. 08, 2016Warrant€ / shares	Nov. 05, 2015WarrantTranches€ / sharesshares	May 05, 2014WarrantTranches€ / sharesshares	May 06, 2013Warrant€ / sharesshares	Oct. 29, 2010Warrant€ / sharesshares	Dec. 31, 2019EUR (€)Warrant€ / shares	Dec. 31, 2018EUR (€)Warrant€ / shares	Dec. 31, 2017Warrant€ / shares	Dec. 31, 2015	Dec. 31, 2014
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrant exercised						100,000	253,150	61,050	0	4,500
Number of warrants authorized | shares	939,500	700,000	520,000		466,000	100,000	266,241	79,500
Number of warrants offered	273,500	426,050	334,400		353,550	94,400	253,150	61,050	610,250	111,600
Number of warrants outstanding	273,500	401,350	285,084		250,982	35,698	2,500	766	1,292,380	731,229	674,962
Warrants expiration date	3 years	3 years	3 years	3 years	3 years	3 years	3 years	3 years
Percentage of warrants vested	100.00%	100.00%	100.00%	100.00%	100.00%	100.00%	100.00%	100.00%
Exercise price of the different tranches ranges | € / shares	€ 8.16						€ 2.64	€ 35.36	€ 22.56	€ 30.71	€ 31.76
Warrants exercise period	5 years	5 years	5 years	5 years	10 years	10 years	10 years	10 years			Over four different exercise periods	Over three different exercise periods	Over four different exercise periods
Number of tranches | Tranches					5	5
Number of warrants cancelled									24,100	50,833
Net expense recognized | €									€ 2.8	€ 3.6
Warrants Issued And Outstanding Percentage									8.48%
Bottom of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise price of the different tranches ranges | € / shares		€ 9.36	€ 31.34	€ 17.60	€ 15.90	€ 33.49
Top of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise price of the different tranches ranges | € / shares		€ 22.04	€ 48.89	€ 36.81	€ 34.65	€ 45.05
Warrant1 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrant exercised											0
New issue of warrants									24,999
Warrants plan issuance date 5 November 2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
New issue of warrants				100,000
Number of warrants offered				42,500
Number of warrants outstanding				45,000
Number of warrants cancelled				100,000

Share-based Payments - Summary

Share-based Payments - Summary of Warrants Outstanding (Detail)	12 Months Ended
	Dec. 31, 2019Warrant	Oct. 25, 2019Warrant	Dec. 31, 2018Warrant€ / shares	Oct. 26, 2018Warrant	Dec. 31, 2017Warrant	Jun. 29, 2017Warrant	Nov. 05, 2015Warrant	May 05, 2014Warrant	May 06, 2013Warrant	Oct. 29, 2010Warrant
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants outstanding as of 31 December, Ex 2016	1,292,380	273,500	731,229	401,350	674,962	285,084	250,982	35,698	2,500	766
29 Oct 2010 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrant plan issuance date	29 October 2010
Vesting date	29 October 2013
Expiry date	29 October 2020
Number of warrants outstanding as of 31 December, Ex 2016	766		766
Exercise price per share | € / shares			€ 35.36
06 May 2013 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrant plan issuance date	06 May 2013
Vesting date	06 May 2016
Expiry date	06 May 2023
Number of warrants outstanding as of 31 December, Ex 2016	2,500		2,500
Exercise price per share | € / shares			€ 2.64
05 May 2014 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrant plan issuance date	05 May 2014
Vesting date	05 May 2017
Expiry date	05 May 2024
Number of warrants outstanding as of 31 December, Ex 2016	35,698		60,697
Exercise price per share | € / shares			€ 38.29
05 November 2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrant plan issuance date	05 November 2015
Vesting date	05 November 2018
Expiry date	05 November 2025
Number of warrants outstanding as of 31 December, Ex 2016	250,982		245,982
Exercise price per share | € / shares			€ 33.39
08 December 2016 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrant plan issuance date	08 December 2016
Vesting date	08 December 2019
Expiry date	08 December 2021
Number of warrants outstanding as of 31 December, Ex 2016	42,500		42,500
Exercise price per share | € / shares			€ 22.41
29 June 2017 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrant plan issuance date	29 June 2017
Vesting date	29 June 2020
Expiry date	29 June 2022
Number of warrants outstanding as of 31 December, Ex 2016	285,084		294,484
Exercise price per share | € / shares			€ 31.44
26 October 2018 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrant plan issuance date	26 October 2018
Vesting date	26 October 2021
Expiry date	19 September 2024
Number of warrants outstanding as of 31 December, Ex 2016	401,350		84,300
Exercise price per share | € / shares			€ 18.07
25 October 2019 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrant plan issuance date	25 October 2019
Vesting date	25 October 2022
Expiry date	25 October 2024
Number of warrants outstanding as of 31 December, Ex 2016	273,500
Exercise price per share | € / shares			€ 8.16

Share-based Payments - Summar_2

Share-based Payments - Summary of Fair Value of Warrants Determined At Grant Date (Detail)	Oct. 25, 2019Warrant	Oct. 26, 2018Warrant	Jun. 29, 2017Warrant	Nov. 05, 2015Warrant	May 05, 2014Warrant	May 06, 2013Warrant	Oct. 29, 2010Warrant	Dec. 31, 2019EUR (€)Warrant€ / shares	Dec. 31, 2018Warrant	Dec. 31, 2017Warrant
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants granted	273,500	426,050	334,400	353,550	94,400	253,150	61,050	610,250	111,600
Number of warrants not fully vested as of 31 December 2019	273,500	401,350	285,084	250,982	35,698	2,500	766	1,292,380	731,229	674,962
Black-Scholes Pricing Model [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants issued								3,311,241
Number of warrants granted								1,981,100
Number of warrants not fully vested as of 31 December 2019								972,434
Average exercise price | € / shares								€ 22.58
Average fair value | €								€ 12.34
Warrant issued 2016 [Member] | Black-Scholes Pricing Model [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants issued								100,000
Number of warrants granted								45,000
Number of warrants not fully vested as of 31 December 2019								12,500
Average exercise price | € / shares								€ 22.41
Expected share value volatility								61.03%
Risk-free interest rate								(0.40%)
Average fair value | €								€ 11.28
Weighted average remaining contractual life								1 year 11 months 8 days
29 June 2017 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants not fully vested as of 31 December 2019								285,084	294,484
29 June 2017 [member] | Black-Scholes Pricing Model [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants issued								520,000
Number of warrants granted								334,400
Number of warrants not fully vested as of 31 December 2019								285,084
Average exercise price | € / shares								€ 31.44
Expected share value volatility								60.61%
Risk-free interest rate								(0.23%)
Average fair value | €								€ 15.65
Weighted average remaining contractual life								2 years 5 months 26 days
05 May 2010 (warrants B) [member] | Black-Scholes Pricing Model [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants issued								79,500
Number of warrants granted								61,050
Average exercise price | € / shares								€ 35.36
Expected share value volatility								35.60%
Risk-free interest rate								3.21%
Average fair value | €								€ 9
Weighted average remaining contractual life								9 months 25 days
05 May 2010 (warrants C) [member] | Black-Scholes Pricing Model [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants issued								140,000
Number of warrants granted								140,000
Average exercise price | € / shares								€ 4.52
Expected share value volatility								35.60%
Risk-free interest rate								2.30%
Average fair value | €								€ 2.22
Weighted average remaining contractual life								3 years 29 days
29 Oct 2010 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants not fully vested as of 31 December 2019								766	766
29 Oct 2010 [member] | Black-Scholes Pricing Model [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants issued								266,241
Number of warrants granted								253,150
Average exercise price | € / shares								€ 2.64
Expected share value volatility								39.55%
Risk-free interest rate								2.06%
Average fair value | €								€ 12.44
Weighted average remaining contractual life								3 years 4 months 2 days
05 May 2014 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants not fully vested as of 31 December 2019								35,698	60,697
05 May 2014 [member] | Black-Scholes Pricing Model [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants issued								100,000
Number of warrants granted								94,400
Average exercise price | € / shares								€ 38.29
Expected share value volatility								67.73%
Risk-free interest rate								1.09%
Average fair value | €								€ 25.22
Weighted average remaining contractual life								4 years 4 months 2 days
05 November 2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants not fully vested as of 31 December 2019								250,982	245,982
05 November 2015 [member] | Black-Scholes Pricing Model [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants issued								466,000
Number of warrants granted								353,550
Average exercise price | € / shares								€ 33.39
Expected share value volatility								60.53%
Risk-free interest rate								0.26%
Average fair value | €								€ 21.73
Weighted average remaining contractual life								5 years 10 months 2 days
25 October 2019 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants not fully vested as of 31 December 2019								273,500
25 October 2019 [member] | Black-Scholes Pricing Model [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants issued								939,500
Number of warrants granted								273,500
Number of warrants not fully vested as of 31 December 2019								273,500
Average exercise price | € / shares								€ 8.16
Expected share value volatility								59.14%
Risk-free interest rate								(0.38%)
Average fair value | €								€ 3.97
Weighted average remaining contractual life								4 years 9 months 25 days
26 October 2018 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants not fully vested as of 31 December 2019								401,350	84,300
26 October 2018 [member] | Black-Scholes Pricing Model [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants issued								700,000
Number of warrants granted								426,050
Number of warrants not fully vested as of 31 December 2019								401,350
Average exercise price | € / shares								€ 18.07
Expected share value volatility								58.82%
Risk-free interest rate								(0.06%)
Average fair value | €								€ 8.80
Weighted average remaining contractual life								3 years 9 months 25 days

Post Employment Benefits - Summ

Post Employment Benefits - Summary of Pension Obligations (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018
Disclosure of defined benefit plans [abstract]
Pension obligations	€ 398	€ 131
Total	€ 398	€ 131

Post Employment Benefits - Addi

Post Employment Benefits - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019EUR (€)	Dec. 31, 2018EUR (€)yr
Disclosure of net defined benefit liability (asset) [abstract]
Employee contributions | €	€ 0
Mortality rate for men | yr		5
Mortality rate for women | yr		5
Actuarial assumption of withdrawal rate each year		15.00%
Actuarial assumption of retirement age		65 years
Yearly inflation rate		1.80%
Actuarial assumption of yearly salary raise above inflation		1.50%
Actuarial assumption of yearly discount rates		1.20%
Percentage of reasonably possible increase decrease in actuarial assumption description	If the discount rate would decrease with 0,5% then, the defined benefit obligation would increase with 6.2%. Reversely if the discount rate would increase with 0,5% then the defined benefit obligation would decrease with 6.6%.
Expected contributions to pension benefit plans | €		€ 200,000

Post Employment Benefits - Su_2

Post Employment Benefits - Summary of Defined Benefit Amounts Recognized in Balance Sheet (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018
Disclosure of net defined benefit liability (asset) [abstract]
Present value of funded obligations	€ 2,330	€ 1,838
Fair value of plan assets	(1,932)	(1,706)
Deficit of funded plans	398	131
Total deficit of defined benefit pension plans	398	131
Liability in the balance sheet	€ 398	€ 131

Post Employment Benefits - Su_3

Post Employment Benefits - Summary of Change in Defined Benefit Liability (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure of net defined benefit liability (asset) [line items]
Beginning balance	€ 131	€ 204
Current service cost	193	190
Interest expense/(income)	13	5
Increase (decrease) in net defined benefit liability (asset)	339	399
Remeasurements
- Return on plan assets, excluding amounts included in interest expense/(income)	8	(9)
- Actuarial (Gain)/loss due to change in actuarial assumptions	222	(58)
- Actuarial (Gain)/Loss due to experience	70	(3)
Remeasurement of post-employment benefit obligation	301	(70)
Employer contributions:	(233)	(198)
Ending balance	398	131
Present value of obligation [member]
Disclosure of net defined benefit liability (asset) [line items]
Beginning balance	1,838	1,704
Current service cost	193	190
Interest expense/(income)	44	36
Increase (decrease) in net defined benefit liability (asset)	2,076	1,929
Remeasurements
- Actuarial (Gain)/loss due to change in actuarial assumptions	222	(58)
- Actuarial (Gain)/Loss due to experience	70	(3)
Remeasurement of post-employment benefit obligation	292	(61)
Employer contributions:	0	0
Benefits Paid	(38)	(31)
Ending balance	2,330	1,838
Fair value of plan assets [member]
Disclosure of net defined benefit liability (asset) [line items]
Beginning balance	1,707	1,499
Current service cost	0	0
Interest expense/(income)	31	31
Increase (decrease) in net defined benefit liability (asset)	1,737	1,530
Remeasurements
- Return on plan assets, excluding amounts included in interest expense/(income)	0	9
- Actuarial (Gain)/loss due to change in actuarial assumptions	0	0
- Actuarial (Gain)/Loss due to experience	0	0
Remeasurement of post-employment benefit obligation		9
Employer contributions:	233	198
Benefits Paid	(38)	(31)
Ending balance	€ 1,932	€ 1,707

Post Employment Benefits - Su_4

Post Employment Benefits - Summary of Income Statement Charge Included in Operating Profit for Post- employment Benefits (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure of net defined benefit liability (asset) [abstract]
Current service cost	€ 193	€ 190
Interest expense on DBO	44	36
Expected return on plan assets	(40)	(30)
Net periodic pension cost	€ 198	€ 195

Post Employment Benefits - Su_5

Post Employment Benefits - Summary of Re-measurements Included in Other Comprehensive Loss (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure of net defined benefit liability (asset) [abstract]
Effect of changes in actuarial assumptions	€ 222	€ (58)
Effect of experience adjustments	70	(3)
(Gain)/Loss on assets for the year	8	(9)
Remeasurement of post-employment benefit obligations	€ 301	€ (70)

Other Reserves - Summary of Inf

Other Reserves - Summary of Information on Other Reserves (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure of information on other reserves [Line Items]
Other reserves beginning balance	€ 25,667	€ 23,322
Vested share-based payments	2,775	3,539
Currency Translation differences subsidiaries	(261)	(1,194)
Other reserves ending balance	28,181	25,667
Share based payment reserve [member]
Disclosure of information on other reserves [Line Items]
Other reserves beginning balance	10,246	6,707
Vested share-based payments	2,775	3,539
Currency Translation differences subsidiaries	0	0
Other reserves ending balance	13,021	10,246
Convertible loan [member]
Disclosure of information on other reserves [Line Items]
Other reserves beginning balance	16,631	16,631
Vested share-based payments	0	0
Currency Translation differences subsidiaries	0	0
Other reserves ending balance	16,631	16,631
Translation [member]
Disclosure of information on other reserves [Line Items]
Other reserves beginning balance	(1,211)	(17)
Vested share-based payments	0	0
Currency Translation differences subsidiaries	(261)	(1,194)
Other reserves ending balance	€ (1,472)	€ (1,211)

Advances repayable - Summary of

Advances repayable - Summary of Current and Non-current Portion Financial Liabilities (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018
Disclosure of financial liabilities [abstract]
Non-Current portion as at 1st January	€ 2,864	€ 1,544
Non-Current portion as at 31 December	4,139	2,864
Current portion as at 1st January	276	226
Current portion as at 31 December	346	276
Total Recoverable Cash Advances at 1st January	3,140	1,770
Total Recoverable Cash Advances 31 December	€ 4,484	€ 3,140

Advances Repayable - Additional

Advances Repayable - Additional Information (Detail) € in Thousands	12 Months Ended
	Dec. 31, 2019EUR (€)
Disclosure of financial liabilities [line items]
Contracted recoverable cash advances	€ 34,828
Recoverable cash advances banked	26,300
Existing contracts amounts	6,975
Contractual amount	1,500
5915 [member]
Disclosure of financial liabilities [line items]
Contracted recoverable cash advances	€ 910
Percentage of budgeted project cost	70.00%
Payment equivalent percentage of price received	10.00%
Payment equivalent percentage of price received	100.00%
Other contracts [member]
Disclosure of financial liabilities [line items]
Percentage of budgeted project cost	200.00%
Sales independent reimbursements equivalent percentage of principal amount	30.00%
Other contracts [member] | Bottom of range [member]
Disclosure of financial liabilities [line items]
Percentage of budgeted project cost	45.00%
Other contracts [member] | Top of range [member]
Disclosure of financial liabilities [line items]
Percentage of budgeted project cost	70.00%

Advances repayable - Summary _2

Advances repayable - Summary of Information on Other Outstanding Advances (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure of financial liabilities [line items]
Amounts received prior years		€ 22,559
Amounts received, Previous years	€ 34,828
Amounts received	2,593	1,187
Amounts received Cumulated cashed in	26,339
To receive in 2018 and beyond	6,975
Amount reimbursed (cumulative)	€ 3,581
5160 [member]
Disclosure of financial liabilities [line items]
Project	C-Cure
Amounts received prior years		2,920
Amounts received, Previous years	€ 2,920
Amounts received Cumulated cashed in	€ 2,920
Status	Abandoned
5731 [member]
Disclosure of financial liabilities [line items]
Project	C-Cure
Amounts received prior years		3,400
Amounts received, Previous years	€ 3,400
Amounts received Cumulated cashed in	€ 3,400
Status	Abandoned
5914 [member]
Disclosure of financial liabilities [line items]
Project	C-Cure
Amounts received prior years		687
Amounts received, Previous years	€ 700
Amounts received Cumulated cashed in	€ 687
Status	Abandoned
Amount reimbursed (cumulative)	€ 180
5915 [member]
Disclosure of financial liabilities [line items]
Project	C-Cathez
Amounts received prior years		910
Amounts received, Previous years	€ 910
Amounts received Cumulated cashed in	€ 910
Status	Exploitation
Amount reimbursed (cumulative)	€ 530
5951 [member]
Disclosure of financial liabilities [line items]
Project	Industrialization
Amounts received prior years		866
Amounts received, Previous years	€ 1,470
Amounts received Cumulated cashed in	€ 866
Status	Abandoned
Amount reimbursed (cumulative)	€ 245
6003 [member]
Disclosure of financial liabilities [line items]
Project	C-Cure
Amounts received prior years		1,715
Amounts received, Previous years	€ 1,729
Amounts received Cumulated cashed in	€ 1,715
Status	Abandoned
6230 [member]
Disclosure of financial liabilities [line items]
Project	C-Cure
Amounts received prior years		1,084
Amounts received, Previous years	€ 1,084
Amounts received Cumulated cashed in	€ 1,084
Status	Abandoned
6363 [member]
Disclosure of financial liabilities [line items]
Project	C-Cure
Amounts received prior years		1,126
Amounts received, Previous years	€ 1,140
Amounts received Cumulated cashed in	€ 1,126
Status	Abandoned
Amount reimbursed (cumulative)	€ 1,536
6548 [member]
Disclosure of financial liabilities [line items]
Project	Industrialization
Amounts received prior years		541
Amounts received, Previous years	€ 660
Amounts received Cumulated cashed in	€ 541
Status	Abandoned
6633 [member]
Disclosure of financial liabilities [line items]
Project	C-Cathez
Amounts received prior years		1,020
Amounts received, Previous years	€ 1,020
Amounts received Cumulated cashed in	€ 1,020
Status	Exploitation
Amount reimbursed (cumulative)	€ 245
6646 [member]
Disclosure of financial liabilities [line items]
Project	Proteins
Amounts received prior years		450
Amounts received, Previous years	€ 1,200
Amounts received Cumulated cashed in	€ 450
Status	Abandoned
Amount reimbursed (cumulative)	€ 450
7027 [member]
Disclosure of financial liabilities [line items]
Project	C-Cathez
Amounts received prior years		2,500
Amounts received, Previous years	€ 2,500
Amounts received Cumulated cashed in	€ 2,500
Status	Exploitation
Amount reimbursed (cumulative)	€ 375
7246 [member]
Disclosure of financial liabilities [line items]
Project	C-Cure
Amounts received prior years		2,467
Amounts received, Previous years	€ 2,467
Amounts received Cumulated cashed in	€ 2,467
Status	Abandoned
7502 [member]
Disclosure of financial liabilities [line items]
Project	CAR-T
Amounts received prior years		2,000
Amounts received, Previous years	€ 2,000
Amounts received Cumulated cashed in	€ 2,000
Status	Exploitation
Amount reimbursed (cumulative)	€ 20
7685 [member]
Disclosure of financial liabilities [line items]
Project	THINK
Amounts received prior years		873
Amounts received, Previous years	€ 3,496
Amounts received	1,086	1,187
Amounts received Cumulated cashed in	€ 3,146
To receive in 2018 and beyond		€ 350
Status	Research
8087 [member]
Disclosure of financial liabilities [line items]
Project	CYAD01-Deplethink
Amounts received, Previous years	€ 2,492
Amounts received	623
Amounts received Cumulated cashed in	623
To receive in 2018 and beyond	€ 1,869
Status	Research
8088 [member]
Disclosure of financial liabilities [line items]
Project	CYAD02-Cycle1
Amounts received, Previous years	€ 3,538
Amounts received	885
Amounts received Cumulated cashed in	885
To receive in 2018 and beyond	€ 2,654
Status	Research
1910028 [member]
Disclosure of financial liabilities [line items]
Project	CwalityCAR
Amounts received, Previous years	€ 2,102
To receive in 2018 and beyond	€ 2,102
Status	Research

Advances repayable - Certain Te

Advances repayable - Certain Terms and Conditions for Recoverable Cash Advances (Detail)	12 Months Ended
	Dec. 31, 2019
5160 [member]
Disclosure of financial liabilities [line items]
Research phase	01/05/05-30/04/08
Percentage of total project costs	70.00%
Turnover- dependent reimbursment	0.18%
Turnover-independant reimbursement	Consolidated with 6363
Interest rate accrual	N/A
Amount due in case of licensing (per year) resp.Sale	N/A
5731 [member]
Disclosure of financial liabilities [line items]
Research phase	01/05/08-31/10/09
Percentage of total project costs	70.00%
Turnover- dependent reimbursment	0.18%
Turnover-independant reimbursement	Consolidated with 6363
Interest rate accrual	N/A
Amount due in case of licensing (per year) resp.Sale	N/A
5914 [member]
Disclosure of financial liabilities [line items]
Research phase	01/09/08-30/06/11
Percentage of total project costs	70.00%
Turnover- dependent reimbursment	5.00%
Turnover-independant reimbursement	€30k in 2012 and €70k each year after
Interest rate accrual	N/A
Amount due in case of licensing (per year) resp.Sale	10% with a minimum of 100/Y
5915 [member]
Disclosure of financial liabilities [line items]
Research phase	01/08/08-30/04/11
Percentage of total project costs	70.00%
Turnover- dependent reimbursment	5.00%
Turnover-independant reimbursement	€40k in 2012 and €70k each year after
Interest rate accrual	N/A
Amount due in case of licensing (per year) resp.Sale	10% with a minimum of 100/Y
5951 [member]
Disclosure of financial liabilities [line items]
Research phase	01/09/08-31/12/14
Percentage of total project costs	70.00%
Turnover- dependent reimbursment	5.00%
Turnover-independant reimbursement	€100k in 2014 and €150k each year after
Interest rate accrual	N/A
Amount due in case of licensing (per year) resp.Sale	10% with a minimum of 200/Y
6003 [member]
Disclosure of financial liabilities [line items]
Research phase	01/01/09-30/09/11
Percentage of total project costs	60.00%
Turnover- dependent reimbursment	0.18%
Turnover-independant reimbursement	Consolidated with 6363
Interest rate accrual	N/A
Amount due in case of licensing (per year) resp.Sale	N/A
6230 [member]
Disclosure of financial liabilities [line items]
Research phase	01/01/10-31/03/12
Percentage of total project costs	60.00%
Turnover- dependent reimbursment	0.18%
Turnover-independant reimbursement	Consolidated with 6363
Interest rate accrual	N/A
Amount due in case of licensing (per year) resp.Sale	N/A
6363 [member]
Disclosure of financial liabilities [line items]
Research phase	01/03/10-30/06/12
Percentage of total project costs	60.00%
Turnover- dependent reimbursment	0.18%
Turnover-independant reimbursement	From €103k to €514k starting in 2013 until 30% of advance is reached
Interest rate accrual	Starting on 01/01/13
Amount due in case of licensing (per year) resp.Sale	N/A
6548 [member]
Disclosure of financial liabilities [line items]
Research phase	01/01/11-31/03/13
Percentage of total project costs	60.00%
Turnover- dependent reimbursment	0.01%
Turnover-independant reimbursement	From €15k to €29k starting in 2014 until 30% of advance is reached
Interest rate accrual	Starting on 01/10/13
Amount due in case of licensing (per year) resp.Sale	N/A
6633 [member]
Disclosure of financial liabilities [line items]
Research phase	01/05/11-30/11/12
Percentage of total project costs	60.00%
Turnover- dependent reimbursment	0.27%
Turnover-independant reimbursement	From €10k to €51k starting in 2013 until 30% of advance is reached
Interest rate accrual	Starting on 01/06/13
Amount due in case of licensing (per year) resp.Sale	N/A
6646 [member]
Disclosure of financial liabilities [line items]
Research phase	01/05/11-30/06/15
Percentage of total project costs	60.00%
Turnover- dependent reimbursment	0.01%
Turnover-independant reimbursement	From €12k to €60k starting in 2015 until 30% of advance is reached
Interest rate accrual	Starting on 01/01/16
Amount due in case of licensing (per year) resp.Sale	N/A
7027 [member]
Disclosure of financial liabilities [line items]
Research phase	01/11/12-31/10/14
Percentage of total project costs	50.00%
Turnover- dependent reimbursment	0.33%
Turnover-independant reimbursement	From €25k to €125k starting in 2015 until 30% of advance is reached
Interest rate accrual	Starting on 01/01/15
Amount due in case of licensing (per year) resp.Sale	N/A
7246 [member]
Disclosure of financial liabilities [line items]
Research phase	01/01/14-31/12/16
Percentage of total project costs	50.00%
Turnover- dependent reimbursment	5.00%
Turnover-independant reimbursement	From €30k to €148k starting in 2017 until 30% of advance is reached.
Interest rate accrual	Starting in 2017
Amount due in case of licensing (per year) resp.Sale	N/A
7502 [member]
Disclosure of financial liabilities [line items]
Research phase	01/12/15-30/11/18
Percentage of total project costs	45.00%
Turnover- dependent reimbursment	0.19%
Turnover-independant reimbursement	From €20k to €50k starting in 2019 until 30% is reached.
Interest rate accrual	Starting 2019
Amount due in case of licensing (per year) resp.Sale	N/A
7685 [member]
Disclosure of financial liabilities [line items]
Research phase	1/01/17-31/12/19
Percentage of total project costs	45.00%
Turnover- dependent reimbursment	0.33%
Turnover-independant reimbursement	From €35k to €70k starting in 2020 until 30% is reached.
Interest rate accrual	Starting 2020
Amount due in case of licensing (per year) resp.Sale	N/A
8087 [member]
Disclosure of financial liabilities [line items]
Research phase	01/05/19-31/12/20
Percentage of total project costs	45.00%
Turnover- dependent reimbursment	0.22%
Turnover-independant reimbursement	From €25k to €75k starting in 2021 until 30% is reached
Interest rate accrual	Starting 01/01/21
Amount due in case of licensing (per year) resp.Sale	N/A
8088 [member]
Disclosure of financial liabilities [line items]
Research phase	01/05/19-31/12/20
Percentage of total project costs	45.00%
Turnover- dependent reimbursment	0.21%
Turnover-independant reimbursement	From €35k to €106k starting in 2021 until 30% is reached
Interest rate accrual	Starting 01/01/21
Amount due in case of licensing (per year) resp.Sale	N/A
1910028 [member]
Disclosure of financial liabilities [line items]
Research phase	06/06/19-05/05/21
Percentage of total project costs	45.00%
Turnover- dependent reimbursment	0.01%
Turnover-independant reimbursement	From €21k to €42k starting in 2022 until 30% is reached
Interest rate accrual	Starting 01/06/21
Amount due in case of licensing (per year) resp.Sale	N/A

Due Dates of the Financial Li_3

Due Dates of the Financial Liabilities - Aggregate Information Material Contractual Obligations and Payments Due (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Lease liabilities	€ 4,134	€ 1,136	€ 909
Finance leases		1,136
Operating leases		2,912
Bank loan	229	510	€ 536
Pension obligations	398	131
Advances repayable (current and non-current)	4,484	3,140
Total - material contractual obligations	9,949	7,829
Less than one year [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Lease liabilities	1,401
Finance leases		484
Operating leases		708
Bank loan	192	281
Advances repayable (current and non-current)	346	276
Total - material contractual obligations	1,939	1,749
One to three years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Lease liabilities	1,952
Finance leases		652
Operating leases		942
Bank loan	37	229
Advances repayable (current and non-current)	490	717
Total - material contractual obligations	2,479	2,540
Three to five years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Lease liabilities	1,100
Operating leases		729
Advances repayable (current and non-current)	486	560
Total - material contractual obligations	1,586	1,290
More than five years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Lease liabilities	385
Operating leases		533
Pension obligations	398	131
Advances repayable (current and non-current)	3,163	1,587
Total - material contractual obligations	€ 3,946	€ 2,250

Trade Payables and Other Curr_3

Trade Payables and Other Current Liabilities - Trade Payables and Other Current Liabilities (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018
Trade and other current payables [abstract]
Total trade payables	€ 6,969	€ 5,916
Other current liabilities
Social security	482	314
Payroll accruals and taxes	1,750	1,351
Other current liabilities	1,016	1,024
Total other current liabilities	3,248	2,690
Total Trade payables and other current liabilities	€ 10,217	€ 8,606

Trade Payables and Other Curr_4

Trade Payables and Other Current Liabilities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019
Disclosure of maturity analysis for non-derivative financial liabilities [abstract]
Trade payable settlement description	Trade payables are non-interest-bearing liabilities and are normally settled on a 90-day terms. Their increase is mainly attributable to timing of clinical operations in the fourth quarter of 2019.

Financial Instruments - Summary

Financial Instruments - Summary of Carrying and Fair Values of Financial Instruments that are not Reported at Fair Value (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2017	Dec. 31, 2016
Financial Liabilities
Bank loans	€ 510	€ 229	€ 536
RCAs liability	3,140	4,484
Financial Assets
Non-current trade receivables	1,743	2,432
Other non-current assets	215	257
Short-term investments	9,197	0
Cash and cash equivalents	40,542	39,338	€ 23,253	€ 48,357
Financial liabilities at amortised cost [member]
Financial Liabilities
Bank loans	510	229
Lease liabilities	1,136	4,134
RCAs liability	3,140	4,484
Trade payables and other current liabilities	5,916	6,969
Total	10,702	15,759
Loans and receivables [member]
Financial Assets
Non-current trade receivables	1,743	2,432
Other non-current assets	215	257
Trade and other receivables		558
Trade receivables and other current assets	367
Short-term investments	9,197	0
Cash and cash equivalents	40,542	39,338
Total	52,065	42,586
At fair value [member]
Financial Liabilities
Bank loans	510	229
Lease liabilities	1,136	4,134
RCAs liability	3,140	4,484
Trade payables and other current liabilities	5,916	6,969
Total	10,702	15,759
Financial Assets
Non-current trade receivables	1,743	2,432
Other non-current assets	215	257
Trade and other receivables		558
Trade receivables and other current assets	367
Short-term investments	9,197	0
Cash and cash equivalents	40,542	39,338
Total	€ 52,065	€ 42,586

Financial Instruments - Summa_2

Financial Instruments - Summary of Carrying and Fair Values of Financial Instruments that are Reported at Fair Value (Detail) - EUR (€) € in Thousands	Dec. 31, 2019	Dec. 31, 2018
Disclosure of detailed information about financial instruments [line items]
Investment in equity securities	€ 0	€ 639
Financial assets, at fair value	0
Financial liabilities, at fair value	24,754
Contingent consideration and other financial liabilities [member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, at fair value	24,754
Level I [member]
Disclosure of detailed information about financial instruments [line items]
Investment in equity securities	0
Financial assets, at fair value	0
Level III [member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, at fair value	24,754
Level III [member] | Contingent consideration and other financial liabilities [member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, at fair value	€ 24,754

Financial Instruments - Summa_3

Financial Instruments - Summary of Contingent Consideration and Other Financial Liabilities (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure of significant unobservable inputs used in fair value measurement of liabilities [line items]
Closing balance contingent consideration and other financial liabilities at December 31	€ 24,754	€ 25,187
Contingent consideration [Member]
Disclosure of significant unobservable inputs used in fair value measurement of liabilities [line items]
Opening balance Contingent consideration at 1 January	20,282	15,549
Fair value adjustment	(430)	4,733
Closing balance Contingent consideration at 31 December	19,853	20,282
Opening balance Other financial liabilities at 1 January	4,905	4,034
Fair value adjustment	(4)	871
Closing balance Other financial liabilities at 31 December	4,901	4,905
Closing balance contingent consideration and other financial liabilities at December 31	€ 24,754	€ 25,187

Financial Instruments - Schedul

Financial Instruments - Schedule of Sensitivity Analysis on Fair Value of Contingent Consideration (Detail) € in Millions	12 Months Ended
	Dec. 31, 2019EUR (€)
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Probablity of success percentage	6.30%
Probabilities of success 20 percentage decrease [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 19.8
Impact (%)	(20.00%)
Probabilities of success 10 percentage decrease [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 22.3
Impact (%)	(10.00%)
Probabilities of success [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 24.8
Probabilities of success 10 percentage increase [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 27.2
Impact (%)	10.00%
Probabilities of success 20 percentage increase [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 29.7
Impact (%)	20.00%
Sales long-term growth rate in terminal value 40 percentage decrease [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 23.3
Impact (%)	(6.00%)
Sales long-term growth rate in terminal value thirty two point five percentage decrease [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 23.9
Impact (%)	(3.00%)
Sales long-term growth rate in terminal value 25 percentage decrease [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 24.8
Sales long-term growth rate in terminal value seventeen point five zero percentage decrease [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 26
Impact (%)	5.00%
Sales long-term growth rate in terminal value 10 percentage decrease [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 28
Impact (%)	13.00%
Discount rate ten point six percentage increase [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 32.2
Impact (%)	30.00%
Discount rate twelve point six percentage increase [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 28.2
Impact (%)	14.00%
Discount rate fourteen point six percentage increase [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 24.8
Discount rate sixteen point six percentage increase [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 21.9
Impact (%)	(12.00%)
Discount rate eighteen point six percentage increase [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Cont. consideration (€ million)	€ 19.5
Impact (%)	(21.00%)
Phase I [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Probablity of success percentage	100.00%
Phase I to II [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Probablity of success percentage	63.00%
Phase II to III [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Probablity of success percentage	26.00%
Phase III to BLA [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Probablity of success percentage	45.00%
BLA to approval [member]
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Probablity of success percentage	83.00%

Changes in Liabilities arisin_3

Changes in Liabilities arising from Financial Activities - Fair Value Measurements Using Significant Unobservable Inputs (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure of significant unobservable inputs used in fair value measurement of liabilities [line items]
Opening balance at 1 January	€ 510	€ 536
New bank loans	0	220
Installments	(281)	(245)
Closing balance at 31 December	229	510
Opening balance at January 1st	1,136	909
New finance leases	4,204	730
Installments	(1,206)	(503)
Closing balance at December 31	4,134	1,136
Opening balance at January 1st	3,140
Closing balance at December 31	4,484	3,140
RCA's [member]
Disclosure of significant unobservable inputs used in fair value measurement of liabilities [line items]
Opening balance at January 1st	3,140	1,770
Repayments	(256)	(226)
New Liability component	1,481	598
Remeasurement	120	998
Closing balance at December 31	€ 4,484	€ 3,140

Revenues and Net Other Income_3

Revenues and Net Other Income and Expenses - Summary of Revenues (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of disaggregation of revenue from contracts with customers [abstract]
Out-licensing revenue		€ 2,399	€ 3,505
C-CathEZ sales	€ 6		35
Other revenue	0	716
Total	€ 6	€ 3,115	€ 3,540

Revenues and Net Other Income_4

Revenues and Net Other Income and Expenses - Additional Information (Detail) € in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2019EUR (€)	Dec. 31, 2019USD ($)	Dec. 31, 2018EUR (€)	Dec. 31, 2017EUR (€)
Disclosure of disaggregation of revenue from contracts with customers [line items]
Non-current trade receivables	€ 2,432		€ 1,743
Remeasurement of contingent consideration	400	$ 0.4	5,604
Clinical Development milestone payment	36		1,372
Grant income (RCA's)	1,500
R&D tax credit	1,560		€ 310	€ 1,161
Federal Belgian Institute For Health Insurance Inami [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Grant income (RCA's)	200
Regional Government [Member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Grant income (RCA's)	1,600
Top of range [member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Variable consideration related to future regulatory and commercial-based milestones recognized as revenue | $		$ 17.5
Increase (decrease) due to application of IFRS 15 [member] | Mesoblast licence agreement [member]
Disclosure of disaggregation of revenue from contracts with customers [line items]
Upfront payments recognized as revenue	800
Contingent milestone payments recognized as revenue	2,200
Deferred financial income	500
Net out-licensing revenue	€ 2,400

Revenues and Net Other Income_5

Revenues and Net Other Income and Expenses - Summary of Other Operating Income and Expenses (Detail) € in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2019EUR (€)	Dec. 31, 2019USD ($)	Dec. 31, 2018EUR (€)	Dec. 31, 2017EUR (€)
Disclosure of disaggregation of revenue from contracts with customers [abstract]
Remeasurement of contingent consideration	€ 400	$ 0.4	€ 5,604
Clinical Development milestone payment	36		1,372
Remeasurement of RCA's	120		998
Fair value adjustment on securities			182
Other	35		243	€ 41
Total Other Expenses	191		8,399	41
Grant income (RCA's)	1,508		768	824
Grant income (Other)	1,788			56
Fair value adjustment on securities	182
Remeasurement of RCA's				396
Remeasurement of contingent consideration	433			193
R&D tax credit	1,560		310	1,161
Other	102
Total Other Income	€ 5,572		€ 1,078	€ 2,630

Operating Expenses - Summary of

Operating Expenses - Summary of Research and Development Expenses (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Research and Development Expenses [abstract]
Employee expenses	€ 8,362	€ 7,902	€ 7,007
Travel & Living	486	467	359
Clinical study costs	4,713	4,987	3,901
Preclinical study costs	3,711	2,680	1,820
Process development and scale-up	3,765	2,187	3,319
Consulting fees	675	1,522	1,429
IP filing and maintenance fees	260	474	564
Share-based payments	813	1,264	862
Depreciation	1,444	848	1,488
Rent and utilities	746	668	382
Delivery systems	53	117	430
Others	168	461	535
External collaborations			812
Total R&D expenses	€ 25,196	€ 23,577	€ 22,908

Operating Expenses - Additional

Operating Expenses - Additional Information (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure Of Operating Costs And Expenses [line items]
Non-recurring expenses	€ 24,300
Non cash expense from equity settlement	10,600
Total Research and Development expenses	€ 25,196	€ 23,577	€ 22,908
Percentage of changes in research and development expense	7.00%
Changes in general and administrative expenses	€ 1,300
Percentage of increase in general and administrative expenses	13.00%
C-Cure [member]
Disclosure Of Operating Costs And Expenses [line items]
Non-recurring expenses	€ 700
CorQuest Inc [member]
Disclosure Of Operating Costs And Expenses [line items]
Non-recurring expenses	€ 1,200

Operating Expenses - Summary _2

Operating Expenses - Summary of General and Administrative Expenses (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other General And Administrative Expenses [abstract]
Employee expenses	€ 3,542	€ 3,312	€ 2,630
Share-based payments	1,962	2,331	1,707
Rent & Insurances	625	1,097	1,053
Communication & Marketing	607	676	761
Consulting fees	1,532	2,192	2,227
Travel & Living	331	253	211
Post employment benefits	(33)	(3)
Depreciation	345	267	229
Other	159	263	490
Total General and administration	€ 9,070	€ 10,387	€ 9,310

Operating Expenses - Summary _3

Operating Expenses - Summary of Non-recurring Operating Income and Expenses (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2017
Disclosure of general and administrative expense [Line items]
Write-off C-Cure and Corquest assets and derecognition of related liabilities	€ 0	€ (1,932)
Amendment of Celdara Medical and Dartmouth College agreements [member]
Disclosure of general and administrative expense [Line items]
Amendment of Celdara Medical and Dartmouth College agreements		(24,341)
C-Cure IP asset impairment expense [member]
Disclosure of general and administrative expense [Line items]
C-Cure IP asset impairment expense	0	(6,045)
C-Cure RCA reversal income [member]
Disclosure of general and administrative expense [Line items]
C-Cure RCA reversal income	0	5,356
Corquest IP asset impairment expenses [member]
Disclosure of general and administrative expense [Line items]
Corquest IP asset impairment expenses	€ 0	€ (1,244)

Employee Benefit Expenses - Sum

Employee Benefit Expenses - Summary of Employee Expenses (Detail) € in Thousands	12 Months Ended
	Dec. 31, 2019EUR (€)Employees	Dec. 31, 2018EUR (€)Employees	Dec. 31, 2017EUR (€)Employees
Disclosure Of Employee Benefit Expenses [line items]
Number of employees | Employees	107	96	87
Salaries, wages and fees	€ 6,932	€ 6,439	€ 5,461
Executive Committee compensation	2,993	3,235	2,563
Share-based payments	2,775	3,595	2,569
Social security	1,473	1,301	1,277
Post employment benefits	215	217	220
Hospitalisation insurance	138	118	118
Other benefit expense	119	2
Total Employee expenses	€ 14,646	€ 14,906	€ 12,207
Belgium [member]
Disclosure Of Employee Benefit Expenses [line items]
Number of employees | Employees	103	91	83
USA [member]
Disclosure Of Employee Benefit Expenses [line items]
Number of employees | Employees	4	5	4
Clinical and Regulatory,IP,Marketing [member]
Disclosure Of Employee Benefit Expenses [line items]
Number of employees | Employees	26	19	16
Research and development [member]
Disclosure Of Employee Benefit Expenses [line items]
Number of employees | Employees	33	30	29
Manufacturing and quality [member]
Disclosure Of Employee Benefit Expenses [line items]
Number of employees | Employees	32	34	26
General Administration [member]
Disclosure Of Employee Benefit Expenses [line items]
Number of employees | Employees	16	13	16

Employee Benefit Expenses - Add

Employee Benefit Expenses - Additional Information (Detail) € in Millions	12 Months Ended
	Dec. 31, 2019EUR (€)
Disclosure of employee benefits expenses [abstract]
Percentage of increase in staff headcount	9.50%
Changes in share-based payment compensation	€ 0.8

Leases - Summary of Property Pl

Leases - Summary of Property Plant And Equipment Owned And Leased Assets (Detail)Leases - Summary of Property Plant And Equipment Owned And Leased Assets (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Leases [Abstract]
Property, Plant and Equipment owned (excluding right-of-use assets)	€ 1,713	€ 1,867
Right-of-use assets	3,348	1,147
Total Property, Plant and Equipment	€ 5,061	€ 3,014

Leases - Summary of Rights to U

Leases - Summary of Rights to Use Assets (Detail) € in Thousands	12 Months Ended
	Dec. 31, 2019EUR (€)
Disclosure of quantitative information about right-of-use assets [line items]
Opening balance	€ 1,147
Additions for the period	287
Depreciation charge for the period	(1,044)
Closing balance	3,348
Previously stated [member]
Disclosure of quantitative information about right-of-use assets [line items]
Opening balance	1,147
Increase decrease due to application of IFRS 16 [member]
Disclosure of quantitative information about right-of-use assets [line items]
Opening balance	2,958
Property [member]
Disclosure of quantitative information about right-of-use assets [line items]
Opening balance	2,780
Additions for the period	30
Depreciation charge for the period	(399)
Closing balance	2,411
Property [member] | Previously stated [member]
Disclosure of quantitative information about right-of-use assets [line items]
Opening balance	0
Property [member] | Increase decrease due to application of IFRS 16 [member]
Disclosure of quantitative information about right-of-use assets [line items]
Opening balance	2,780
Vehicles [member]
Disclosure of quantitative information about right-of-use assets [line items]
Opening balance	106
Additions for the period	257
Depreciation charge for the period	(90)
Closing balance	273
Vehicles [member] | Previously stated [member]
Disclosure of quantitative information about right-of-use assets [line items]
Opening balance	0
Vehicles [member] | Increase decrease due to application of IFRS 16 [member]
Disclosure of quantitative information about right-of-use assets [line items]
Opening balance	106
Plant and Equipments [member]
Disclosure of quantitative information about right-of-use assets [line items]
Opening balance	1,219
Additions for the period	0
Depreciation charge for the period	(555)
Closing balance	664
Plant and Equipments [member] | Previously stated [member]
Disclosure of quantitative information about right-of-use assets [line items]
Opening balance	1,147
Plant and Equipments [member] | Increase decrease due to application of IFRS 16 [member]
Disclosure of quantitative information about right-of-use assets [line items]
Opening balance	€ 72

Leases - Summary of lease expen

Leases - Summary of lease expense (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Depreciation charge of right-of-use assets
Depreciation, right-of-use assets	€ 1,044
Interest on lease liabilities (including in Financial expenses)	291	€ 18	€ 18
Interest on sublease receivable (including in Financial income)	(62)
Expenses relating to short-term leases and leases of low-value assets	182
Total expenses related to leases	1,450
Property Member [Member]
Depreciation charge of right-of-use assets
Depreciation, right-of-use assets	399
Vehicles [member]
Depreciation charge of right-of-use assets
Depreciation, right-of-use assets	90
Plant and Equipments [Member]
Depreciation charge of right-of-use assets
Depreciation, right-of-use assets	€ 555

Leases - Summary of Cash Outflo

Leases - Summary of Cash Outflow For Leases (Detail) € in Thousands	12 Months Ended
	Dec. 31, 2019EUR (€)
Disclosure of quantitative information about right-of-use assets [line items]
Total cash outflow for leases	€ 1,679

Financial Income and Expenses -

Financial Income and Expenses - Summary of Financial Revenues and Expenses (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of detailed information about financial instruments [abstract]
Interest on leases	€ 291	€ 18	€ 18
Interest on overdrafts and other finance costs	35	29	36
Interest on RCAs	17	15	90
Foreign Exchange differences			4,309
Finance expenses	343	62	4,454
Finance income on the net investment in lease	62
Interest income bank account	30	308	927
Foreign Exchange differences	326	387
Other financial income	164	109	6
Finance income	582	804	933
Net Financial result	€ 239	€ 743	€ (3,518)

Financial Income and Expenses_2

Financial Income and Expenses - Additional Information (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
TextBlockAbstract [Abstract]
Net Financial result	€ 239	€ 743	€ (3,518)
Change in value of finance leases interests	200
Change in value of interest income bank account	€ 300

Income Tax expense - Summary of

Income Tax expense - Summary of Group Reports Income Taxes in the Income Statement (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Major components of tax expense (income) [abstract]
Current tax (expense) / income	€ 8	€ 0	€ 1
Deferred tax (expense) / income	0
Total income tax expense in profit or loss	€ 8	€ 0	€ 1

Income Tax - Additional Informa

Income Tax - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Applicable tax rate	29.58%	29.58%	33.99%
United States of America, Dollars
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Applicable tax rate	22.83%

Income Tax - Schedule of Reconc

Income Tax - Schedule of Reconciliation Between Effective And Theoretical Income Tax (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred tax expense (income) [abstract]
Loss before tax	€ (28,640)	€ (37,428)	€ (56,396)
Tax disallowed expenses	967	269	221
Share-based payment	€ 2,775	€ 3,595	€ 2,569
Nominal tax rate	29.58%	29.58%	33.99%
Tax income at nominal taxe rate	€ 7,365	€ 9,928	€ 18,220
Deferred Tax assets not recognised	(7,357)	(9,928)	(18,219)
Effective tax expense	€ 8	€ 0	€ 1
Effective tax rate	0.00%	0.00%	0.00%

Deferred Taxes - Schedule of Un

Deferred Taxes - Schedule of Unrecognized Deferred Tax Assets and Liabilities (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Deferred Tax Assets And Liabilities [line items]
Unrecognized deferred tax assets	€ 0
Unrecognized deferred tax liabilities	0
Unrecognized deferred tax assets and liabilities, net	61,300	€ 53,279	€ 48,839	€ 39,370
Netting by tax entity	0
Unrecognized Net Deferred Tax assets/(liabilities)	61,300	53,279	48,839
Intangible asset [member]
Disclosure of Deferred Tax Assets And Liabilities [line items]
Unrecognized deferred tax assets	0	49
Unrecognized deferred tax liabilities	(894)		(3,974)
Unrecognized deferred tax assets and liabilities, net	(894)	49	(3,974)
Tangible assets [member]
Disclosure of Deferred Tax Assets And Liabilities [line items]
Unrecognized deferred tax assets	0
Unrecognized deferred tax liabilities	(90)	(154)	(215)
Unrecognized deferred tax assets and liabilities, net	(90)	(154)	(215)
Deferred tax asset [member]
Disclosure of Deferred Tax Assets And Liabilities [line items]
Unrecognised Gross Deferred Tax assets/(liabilities)	62,758	53,869	53,028
Netting by tax entity	(1,365)	(437)	(3,974)
Unrecognized Net Deferred Tax assets/(liabilities)	61,393	53,432	49,054
Deferred tax liabilities [member]
Disclosure of Deferred Tax Assets And Liabilities [line items]
Unrecognised Gross Deferred Tax assets/(liabilities)	(1,458)	(590)	(4,189)
Netting by tax entity	1,365	437	3,974
Unrecognized Net Deferred Tax assets/(liabilities)	(93)	(153)	(215)
Contingent consideration liabilities [member]
Disclosure of Deferred Tax Assets And Liabilities [line items]
Unrecognized deferred tax assets	6,189	6,297	4,471
Unrecognized deferred tax liabilities	0
Unrecognized deferred tax assets and liabilities, net	6,189	6,297	4,471
RCA's [member]
Disclosure of Deferred Tax Assets And Liabilities [line items]
Unrecognized deferred tax assets	1,056	633	349
Unrecognized deferred tax liabilities	0
Unrecognized deferred tax assets and liabilities, net	1,056	633	349
Employee benefits liability [member]
Disclosure of Deferred Tax Assets And Liabilities [line items]
Unrecognized deferred tax assets	100	33	51
Unrecognized deferred tax liabilities	0
Unrecognized deferred tax assets and liabilities, net	100	33	51
Other temporary differences [member]
Disclosure of Deferred Tax Assets And Liabilities [line items]
Unrecognized deferred tax assets	0		5
Unrecognized deferred tax liabilities	(473)	(436)
Unrecognized deferred tax assets and liabilities, net	(473)	(436)	5
Tax Losses Carry forward [member]
Disclosure of Deferred Tax Assets And Liabilities [line items]
Unrecognized deferred tax assets	55,414	46,858	48,152
Unrecognized deferred tax liabilities	0
Unrecognized deferred tax assets and liabilities, net	€ 55,414	€ 46,858	€ 48,152

Deferred Taxes - Schedule of _2

Deferred Taxes - Schedule of Unrecognised Deferred Tax Asset Balance Roll Forward (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Opening balance	€ 53,279	€ 48,839	€ 39,370
Temporary difference creation or reversal	(536)	5,734	(15,580)
Change in Tax-losses carried forward	8,556	(1,294)	44,011
Change in tax rate applicable			(113)
Closing balance	€ 61,300	€ 53,279	48,839
Belgium [member] | 34% > 25% [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Change in tax rate applicable			(14,896)
USA [member] | 35% > 23% [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Change in tax rate applicable			€ (3,953)

Commitments - Additional Inform

Commitments - Additional Information (Detail)	Jun. 27, 2018USD ($)	Apr. 03, 2018USD ($)	Dec. 31, 2019EUR (€)	Dec. 31, 2019USD ($)	Dec. 31, 2018EUR (€)	Dec. 31, 2017EUR (€)
Disclosure of commitments [line items]
Net Revenue | €			€ 6,000		€ 3,115,000	€ 3,540,000
Royalties percentage on its direct net sales			2.00%	2.00%
Bottom of range [member]
Disclosure of commitments [line items]
Percentage of revenue			23.00%	23.00%
Top of range [member]
Disclosure of commitments [line items]
Percentage of revenue			5.00%	5.00%
CorQuest Inc [member]
Disclosure of commitments [line items]
Share Purchase Agreement Date			Nov. 5, 2014	Nov. 5, 2014
CorQuest Inc [member] | Bottom of range [member]
Disclosure of commitments [line items]
Net Revenue | €			€ 10,000,000
CorQuest Inc [member] | Top of range [member]
Disclosure of commitments [line items]
Earn-Out royalty | €			0.04
Net Revenue | €			10,000,000
Corquest Medical Inc [member] | Bottom of range [member]
Disclosure of commitments [line items]
Earn-Out royalty | €			€ 0.02
Celdara Medical [member]
Disclosure of commitments [line items]
Share Purchase Agreement Date			Jan. 21, 2015	Jan. 21, 2015
Celdara Medical [member] | Scenario one [member] | Oncyte LLC
Disclosure of commitments [line items]
Cumulative worldwide net sales				$ 250,000,000
Celdara Medical [member] | Scenario one [member] | Affiliates and sublicensees [member]
Disclosure of commitments [line items]
Percentage of cumulative net sales of products by affiliates and sublicensees based on cumulative worldwide net sales			5.00%	5.00%
Celdara Medical [member] | Scenario two [Member] | Oncyte LLC
Disclosure of commitments [line items]
Cumulative worldwide net sales				$ 500,000,000
Celdara Medical [member] | Scenario two [Member] | Affiliates and sublicensees [member]
Disclosure of commitments [line items]
Percentage of cumulative net sales of products by affiliates and sublicensees based on cumulative worldwide net sales			6.00%	6.00%
Celdara Medical [member] | Scenario three [Member] | Oncyte LLC
Disclosure of commitments [line items]
Cumulative worldwide net sales				$ 1,000,000,000
Celdara Medical [member] | Scenario three [Member] | Affiliates and sublicensees [member]
Disclosure of commitments [line items]
Percentage of cumulative net sales of products by affiliates and sublicensees based on cumulative worldwide net sales			7.00%	7.00%
Celdara Medical [member] | Scenario four [Member] | Affiliates and sublicensees [member]
Disclosure of commitments [line items]
Percentage of cumulative net sales of products by affiliates and sublicensees based on cumulative worldwide net sales			8.00%	8.00%
Celdara Medical [member] | first patient of a Phase II trial [Member]
Disclosure of commitments [line items]
Development and regulatory milestones on other preclinical products				$ 4,000,000
Development and regulatory milestones				6,000,000
Celdara Medical [member] | first patient of the second cohort of the Phase I trial [Member]
Disclosure of commitments [line items]
Development and regulatory milestones				5,000,000
Celdara Medical [member] | first patient of a Phase III trial [Member]
Disclosure of commitments [line items]
Development and regulatory milestones on other preclinical products				6,000,000
Development and regulatory milestones				9,000,000
Celdara Medical [member] | First regulatory approval of CAR-T NKR-2 [Member]
Disclosure of commitments [line items]
Development and regulatory milestones on other preclinical products				10,000,000
Development and regulatory milestones				11,000,000
Celdara Medical [member] | CAR-T NKR-2 is approved for commercialization in the US [Member]
Disclosure of commitments [line items]
Development and regulatory milestones on other preclinical products				15,000,000
Development and regulatory milestones				14,000,000
Celdara Medical [member] | IND to FDA [member]
Disclosure of commitments [line items]
Development and regulatory milestones on other preclinical products				1,500,000
Celdara Medical [member] | Bottom of range [member] | Scenario one [member] | Oncyte LLC
Disclosure of commitments [line items]
Amount of cumulative net sales of products from acquired entity based on first cumulative worldwide net sales				15,000,000
Celdara Medical [member] | Bottom of range [member] | Scenario one [member] | Affiliates and sublicensees [member]
Disclosure of commitments [line items]
Cumulative worldwide net sales				250,000,000
Celdara Medical [member] | Bottom of range [member] | Scenario two [Member] | Oncyte LLC
Disclosure of commitments [line items]
Amount of cumulative net sales of products from acquired entity based on first cumulative worldwide net sales				25,000,000
Celdara Medical [member] | Bottom of range [member] | Scenario two [Member] | Affiliates and sublicensees [member]
Disclosure of commitments [line items]
Cumulative worldwide net sales				500,000,000
Celdara Medical [member] | Bottom of range [member] | Scenario three [Member] | Oncyte LLC
Disclosure of commitments [line items]
Amount of cumulative net sales of products from acquired entity based on first cumulative worldwide net sales				40,000,000
Celdara Medical [member] | Bottom of range [member] | Scenario three [Member] | Affiliates and sublicensees [member]
Disclosure of commitments [line items]
Cumulative worldwide net sales				500,000,000
Celdara Medical [member] | Top of range [member] | Scenario two [Member] | Affiliates and sublicensees [member]
Disclosure of commitments [line items]
Cumulative worldwide net sales				250,000,000
Celdara Medical [member] | Top of range [member] | Scenario three [Member] | Affiliates and sublicensees [member]
Disclosure of commitments [line items]
Cumulative worldwide net sales				1,000,000,000
Celdara Medical [member] | Top of range [member] | Scenario four [Member] | Affiliates and sublicensees [member]
Disclosure of commitments [line items]
Cumulative worldwide net sales				$ 1,000,000,000
Horizon Discovery Limited [Member] | Royalty [Member]
Disclosure of commitments [line items]
Percent of net sales	2.00%	1.50%
Horizon Discovery Limited [Member] | Sublicense Royalties [Member]
Disclosure of commitments [line items]
Percent of net sales		1.25%
Horizon Discovery Limited [Member] | Upfront Payments [Member]
Disclosure of commitments [line items]
Percent of net sales	15.00%
Horizon Discovery Limited [Member] | Exercise Of The Option 8 [Member]
Disclosure of commitments [line items]
Development and regulatory milestones		$ 100,000
Horizon Discovery Limited [Member] | First Effective IND Filed Relating To Product 9 [Member]
Disclosure of commitments [line items]
Development and regulatory milestones		100,000
Horizon Discovery Limited [Member] | Filing For The First Phase 2 Clinical Trial Relating To First Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones		200,000
Horizon Discovery Limited [Member] | Filing For The First Phase 3 Clinical Trial Relating To First Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones		400,000
Horizon Discovery Limited [Member] | Filing Of The First MAA or NDA Relating To First Product [Member]
Disclosure of commitments [line items]
Development and regulatory milestones	$ 2,000,000	1,250,000
Horizon Discovery Limited [Member] | First MAA or NDA Approval For The First Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	3,000,000	$ 2,000,000
Horizon Discovery Limited [Member] | Exercise Of The Option 10 [member]
Disclosure of commitments [line items]
Development and regulatory milestones	1,250,000
Horizon Discovery Limited [Member] | First Effective IND Filed Relating To First Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	200,000
Horizon Discovery Limited [Member] | Enrollment Of First Patient Phase 2 Relating To First Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	500,000
Horizon Discovery Limited [Member] | Enrollment Of First Patient Phase 3 Relating To First Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	800,000
Horizon Discovery Limited [Member] | First Effective IND Filed Relating To Second Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	200,000
Horizon Discovery Limited [Member] | Enrollment Of First Patient Phase 2 Relating To Second Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	400,000
Horizon Discovery Limited [Member] | Enrollment Of First Patient Phase 3 Relating To Second Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	450,000
Horizon Discovery Limited [Member] | Filing Of The First MAA or NDA Relating To Second Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	700,000
Horizon Discovery Limited [Member] | First MAA or NDA Approval For The Second Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	2,000,000
Horizon Discovery Limited [Member] | First Effective IND Filed Relating To Third Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	100,000
Horizon Discovery Limited [Member] | Enrollment Of First Patient Phase 2 Relating To Third Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	200,000
Horizon Discovery Limited [Member] | Enrollment Of First Patient Phase 3 Relating To Third Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	250,000
Horizon Discovery Limited [Member] | Filing Of The First MAA or NDA Relating To Third Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	300,000
Horizon Discovery Limited [Member] | First MAA or NDA Approval For The Third Product [member]
Disclosure of commitments [line items]
Development and regulatory milestones	$ 1,000,000

Relationships with Third-Part_3

Relationships with Third-Parties - Summary of Remuneration of Key Management Informations (Detail) € in Thousands	Oct. 25, 2019Warrant	Oct. 26, 2018Warrant	Jun. 29, 2017Warrant	Nov. 05, 2015Warrant	May 05, 2014Warrant	May 06, 2013Warrant	Oct. 29, 2010Warrant	Dec. 31, 2019EUR (€)WarrantMembershares	Dec. 31, 2018EUR (€)WarrantMembershares	Dec. 31, 2017EUR (€)Membershares
Disclosure of key management personnel compensation [line items]
Number of EMT members | Member								6	7	8
Number of warrants granted | Warrant	273,500	426,050	334,400	353,550	94,400	253,150	61,050	610,250	111,600
Number of warrants lapsed | Warrant								(24,999)	0
Exercised warrants | Warrant					100,000	253,150	61,050	0	4,500
Key management personnel of entity or parent [member]
Disclosure of key management personnel compensation [line items]
Short term employee benefits								€ 1,112	€ 740	€ 666
Post employee benefits								26	16	14
Share-based compensation								1,005	1,794	1,123
Other employment costs								75	27	30
Management fees								1,789	2,457	1,950
Total benefits								€ 4,006	€ 5,034	€ 3,783
Number of warrants granted								136,500	30,000	179,000
Number of warrants lapsed										(15,225)
Cumulative outstanding warrants | shares								295,500	259,000	306,500
Exercised warrants										168,000
Outstanding payables									€ 803	€ 461

Relationships with Third-Part_4

Relationships with Third-Parties - Summary of Transactions with Non-executive Directors (Detail) € in Thousands	Oct. 25, 2019Warrant	Oct. 26, 2018Warrant	Jun. 29, 2017Warrant	Nov. 05, 2015Warrant	May 05, 2014Warrant	May 06, 2013Warrant	Oct. 29, 2010Warrant	Dec. 31, 2019EUR (€)Warrantshares	Dec. 31, 2018EUR (€)Warrantshares	Dec. 31, 2017EUR (€)Warrantshares
Disclosure of transactions between related parties [line items]
Number of warrants granted | Warrant	273,500	426,050	334,400	353,550	94,400	253,150	61,050	610,250	111,600
Shares owned | Warrant	273,500	401,350	285,084	250,982	35,698	2,500	766	1,292,380	731,229	674,962
Non Executive Directors [Member]
Disclosure of transactions between related parties [line items]
Share-based compensation								€ 430	€ 420	€ 485
Management fees								429	357	387
Total benefits								€ 859	€ 776	€ 872
Number of warrants granted								100,000	20,000	60,000
Number of warrants lapsed								5,000		(2,904)
Cumulative outstanding warrants | shares								190,000	135,000	115,000
Outstanding payables								€ 210	€ 127	€ 194
Shares owned								345,453	345,453	2,512,004

Loss Per Share - Calculation of

Loss Per Share - Calculation of Earnings (Loss) Per Share (Detail) - EUR (€) € / shares in Units, € in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings per share [abstract]
Loss of the year attributable to Equity Holders	[1]	€ (28,632)	€ (37,427)	€ (56,395)
Weighted average number of shares outstanding		12,523,166	11,142,244	9,627,601
Earnings per share (non-fully diluted) in €		€ (2.29)	€ (3.36)	€ (5.86)
Outstanding warrants		1,292,380	731,229	674,962
[1]	For 2019 and 2018, the Company does not have any non-controlling interests and the losses for the year are fully attributable to owners of the parent.