Cellectis (CLLS) 20-F 4 Mar 21 2020 FY Annual report (foreign) Financial data

Cover Page

Cover Page	12 Months Ended
	Dec. 31, 2020shares
Document Information [Line Items]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	CELLECTIS S.A.
Entity Central Index Key	0001627281
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	42,780,186
Entity Shell Company	false
Entity Emerging Growth Company	false
Document Transition Report	false
Document Annual Report	true
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Address, Country	FR
Document Shell Company Report	false
ICFR Auditor Attestation Flag	true
American Depositary Shares [member]
Document Information [Line Items]
Trading Symbol	CLLS
Title of 12(b) Security	American Depositary Shares, each representing one ordinary share, nominal value €0.05 per share
Security Exchange Name	NASDAQ

Statements of Consolidated Fina

Statements of Consolidated Financial Position - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Non-current assets
Intangible assets	$ 1,584	$ 1,108
Property, plant, and equipment	71,673	23,712
Right-of-use assets	73,845	45,612
Other non-current financial assets	7,007	5,517
Total non-current assets	154,109	75,949
Current assets
Inventories	1,606	2,897
Trade receivables	5,171	2,959
Subsidies receivables	10,703	9,140
Other current assets	29,643	15,617
Current financial assets	27,091	20,385
Cash and cash equivalents	241,148	340,522
Total current assets	315,362	391,520
TOTAL ASSETS	469,471	467,469
Shareholders' equity
Share capital	2,785	2,767
Premiums related to the share capital	863,912	843,478
Currency translation adjustment	(4,089)	(22,641)
Retained earnings	(505,961)	(406,390)
Net income (loss)	(81,074)	(102,091)
Total shareholders' equity - Group Share	275,573	315,123
Non-controlling interests	33,273	40,347
Total shareholders' equity	308,846	355,470
Non-current liabilities
Non-current financial liabilities	28,836
Non-current lease debts	75,764	46,540
Non-current provisions	4,010	2,855
Total non-current liabilities	108,610	49,395
Current liabilities
Current lease debts	6,696	1,067
Trade payables	24,609	29,264
Deferred revenues and contract liabilities	452	20,033
Current provisions	1,131	3,743
Other current liabilities	19,127	8,497
Total current liabilities	52,015	62,604
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 469,471	$ 467,469

Statements of Consolidated Oper

Statements of Consolidated Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Profit or loss [abstract]
Revenues	$ 73,949	$ 15,190	$ 12,731
Other income	8,507	7,800	8,701
Total revenues and other income	82,456	22,990	21,432
Operating expenses
Cost of revenue	(36,275)	(11,392)	(2,739)
Research and development expenses	(86,950)	(92,042)	(76,567)
Selling, general and administrative expenses	(44,201)	(43,017)	(47,248)
Other operating income (expenses)	(467)	(91)	31
Total operating expenses	(167,893)	(146,542)	(126,523)
Operating income (loss)	(85,437)	(123,552)	(105,091)
Financial income	5,468	11,971	20,572
Financial expenses	(17,514)	(3,631)	(3,813)
Financial gain (loss)	(12,046)	8,340	16,758
Income tax	0	0	0
Net income (loss)	(97,483)	(115,212)	(88,333)
Attributable to shareholders of Cellectis	(81,074)	(102,091)	(78,693)
Attributable to non-controlling interests	$ (16,409)	$ (13,121)	$ (9,640)
Basic / Diluted net income (loss) per share attributable to shareholders of Cellectis
Basic net income (loss) attributable to shareholders of Cellectis per share ($ /share)	$ (1.91)	$ (2.41)	$ (1.93)
Diluted net income (loss) attributable to shareholders of Cellectis per share ($ /share)	$ (1.91)	$ (2.41)	$ (1.93)

Statements of Consolidated Comp

Statements of Consolidated Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of comprehensive income [abstract]
Net income (loss)	$ (97,483)	$ (115,212)	$ (88,333)
Actuarial gains and losses	(430)	(303)	70
Other comprehensive income (loss) that will not be reclassified subsequently to income or loss	(430)	(303)	70
Currency translation adjustment	19,019	(5,714)	(19,192)
Commodity derivative contracts	0	17
Other comprehensive income (loss) that will be reclassified subsequently to income or loss	19,019	(5,697)	(19,192)
Total Comprehensive income (loss)	(78,894)	(121,212)	(107,455)
Attributable to shareholders of Cellectis	(62,952)	(108,356)	(97,125)
Attributable to non-controlling interests	$ (15,942)	$ (12,856)	$ (10,330)

Statements of Consolidated Cash

Statements of Consolidated Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net income (loss) for the period	$ (97,483)	$ (115,212)	$ (88,333)
Reconciliation of net income (loss) and of the cash provided by
Amortization and depreciation	9,819	6,875	2,377
Net loss (income) on disposals	195	15	20
Net financial loss (gain)	12,045	(8,340)	(16,759)
Expenses related to share-based payments	16,736	26,880	37,218
Provisions	(2,366)	2,093	(468)
Other non cash items	(17)	85
Interest (paid) / received	2,639	6,808	6,905
Operating cash flows before change in working capital	(58,434)	(80,796)	(59,040)
Decrease (increase) in inventories	1,311	(2,627)	(37)
Decrease (increase) in trade receivables and other current assets	(8,338)	(2,674)	(3,696)
Decrease (increase) in subsidies receivables	(685)	7,359	(8,257)
(Decrease) increase in trade payables and other current liabilities	5,802	9,635	9,374
(Decrease) increase in deferred income	(19,918)	(39)	(6,480)
Change in working capital	(21,828)	11,654	(9,096)
Net cash flows provided by (used in) operating activities	(80,262)	(69,142)	(68,137)
Cash flows from investment activities
Proceeds from disposal of property, plant and equipment	54	414	1,262
Acquisition of intangible assets	(567)	(45)	(171)
Acquisition of property, plant and equipment	(45,693)	(12,913)	(4,715)
Net change in non-current financial assets	(1,430)	(3,636)	221
Sale (Acquisition) of current financial assets	(6,706)	(19,692)	39,025
Net cash flows provided by (used in) investing activities	(54,342)	(35,872)	35,623
Cash flows from financing activities
Increase in borrowings	24,170
Decrease in borrowings			(127)
Payments on lease debts	(6,607)	(3,393)
Treasury shares			297
Net cash flows provided by (used in) financing activities	27,322	(3,862)	236,494
(Decrease) increase in cash and cash equivalents	(107,282)	(108,876)	203,981
Cash and cash equivalents at the beginning of the year	340,522	451,501	256,380
Effect of exchange rate changes on cash	7,908	(2,103)	(8,860)
Cash and cash equivalents at the end of the period	241,148	340,522	451,501
Calyxt Inc [Member]
Cash flows from financing activities
Proceeds from the exercise of stock options	210	$ (469)
Increase in share capital	9,205		49,942
Cellectis [Member]
Cash flows from financing activities
Proceeds from the exercise of stock options	$ 344		7,771
Increase in share capital			$ 178,611

Statements of Changes in Consol

Statements of Changes in Consolidated Shareholders' Equity - USD ($) $ in Thousands		Total	Calyxt Inc [member]		Share Capital Ordinary Shares [member]	Premiums Related to Share Capital [member]	Treasury Shares [member]	Currency Translation Adjustment [member]	Retained Earnings (Deficit) [member]	Retained Earnings (Deficit) [member]Calyxt Inc [member]		Income (Loss) [member]	Attributable to Shareholders of Cellectis [member]	Attributable to Shareholders of Cellectis [member]Calyxt Inc [member]		Non controlling Interests [member]	Non controlling Interests [member]Calyxt Inc [member]
Beginning balance at Dec. 31, 2017		$ 283,986			$ 2,367	$ 614,037	$ (297)	$ 1,835	$ (253,702)			$ (99,368)	$ 264,873			$ 19,113
Beginning balance, shares at Dec. 31, 2017					35,960,062
Statement [Line Items]
Net Loss		(88,333)										(78,693)	(78,693)			(9,640)
Other comprehensive income (loss)		(19,122)						(18,502)	70				(18,432)			(690)
Total Comprehensive income (loss)		(107,455)						(18,502)	70			(78,693)	(97,125)			(10,330)
Allocation of prior period loss									(99,368)			99,368
Capital Increase		178,611	$ 49,942	[1]	$ 379	178,230			2	$ 26,454	[1]		178,611	$ 26,454	[1]		$ 23,488	[1]
Capital Increase, Shares					6,146,000
Treasury shares		239					$ 297		(58)				239
Exercise of share warrants and employee warrants, amount		7,770			$ 19	7,751							7,770
Exercise of share warrants and employee warrants, shares					324,007
Non-cash stock-based compensation expense		37,218				28,507							28,507			8,711
Other movements		(40)							(28)				(28)			(12)
Balance at end of year at Dec. 31, 2018		450,272			$ 2,765	828,525		(16,668)	(326,628)			(78,693)	409,301			40,970
Ending balance, shares at Dec. 31, 2018					42,430,069
Statement [Line Items]
Net Loss		(115,212)										(102,091)	(102,091)			(13,121)
Other comprehensive income (loss)		(6,000)						(5,974)	(292)				(6,265)			265
Total Comprehensive income (loss)		(121,212)						(5,974)	(292)			(102,091)	(108,356)			(12,856)
Allocation of prior period loss									(78,693)			78,693
Capital Increase					$ 2				(2)
Capital Increase, Shares					35,600
Exercise of stock options Calyxt ,Values	[2]	(469)							(773)				(773)			304
Non-cash stock-based compensation expense		26,879				14,951							14,950			11,929
Other movements						2			(2)
Balance at end of year at Dec. 31, 2019		355,470			$ 2,767	843,478		(22,641)	(406,390)			(102,091)	315,123			40,347
Ending balance, shares at Dec. 31, 2019					42,465,669
Statement [Line Items]
Net Loss		(97,483)										(81,074)	(81,074)			(16,409)
Other comprehensive income (loss)		18,589						18,552	(430)				18,122			467
Total Comprehensive income (loss)		(78,894)						18,552	(430)			(81,074)	(62,952)			(15,942)
Allocation of prior period loss									(102,091)			102,091
Capital Increase	[3]		$ 9,205							$ 4,243				$ 4,243			$ 4,962
Exercise of stock options Calyxt ,Values	[2]	210							136				136			74
Transaction with subsidiaries									(1,461)				(1,461)			1,461
Exercise of share warrants and employee warrants, amount		6,119			$ 18	6,101							6,119
Exercise of share warrants and employee warrants, shares					314,517
Non-cash stock-based compensation expense		16,736				14,365							14,365			2,371
Other movements						(32)			32
Balance at end of year at Dec. 31, 2020		$ 308,846			$ 2,785	$ 863,912		$ (4,089)	$ (505,961)			$ (81,074)	$ 275,573			$ 33,273
Ending balance, shares at Dec. 31, 2020					42,780,186
[1]	On May 22, 2018, Calyxt Inc completed a follow-on offering of its common stock. Calyxt Inc sold an aggregate of 4,057,500 shares of common stock at a price of $15.00 per share, including 457,500 shares of common stock pursuant to the exercise of the underwriters’ option to purchase additional shares. In the aggregate, Calyxt Inc received net proceeds from the follow-on offering and exercise of the overallotment option of approximately $57.0 million, after deducting underwriting discounts and commissions of $3.2 million and offering expenses totaling approximately $0.7 million. As part of the follow-on offering, Cellectis SA purchased 550,000 shares of common stock for a value of $8.3 million. Transaction with subsidiaries also includes the exercise of 592,342 Calyxt stock options during the period for $2.4 million, partially offset by Cellectis’ purchase on June 14, 2018 of 63,175 shares of Calyxt common stock from employees and nonemployees of Calyxt and Cellectis at a price of $19.49 per share (the closing price reported on the Nasdaq Global Market on June 14, 2018) for $1.2 million.
[2]	Corresponds to the impact of Calyxt stock options exercises during the period.
[3]	On October 20, 2020, Calyxt entered into definitive agreements with institutional investors for the purchase and sale of 3,750,000 shares of Calyxt’s common stock, at a purchase price of $4.00 per share, in an SEC-registered, direct offering. The financing resulted in gross proceeds of $15.0 million before payment of all related fees and expenses. Cellectis purchased 1,250,000 shares in the offering for a value of $5.0 million, the proceeds of which are included in the net proceeds of approximately $14.0 million. Following the registered direct offering, as of December 31, 2020, Cellectis owns approximately 64.7% of Calyxt’s outstanding shares of common stock.

Statements of Changes in Cons_2

Statements of Changes in Consolidated Shareholders' Equity (Parenthetical) - USD ($) $ in Thousands	Oct. 20, 2020	Jun. 14, 2018	May 22, 2018	Oct. 28, 2014	Dec. 31, 2020
Statement [Line Items]
Gross proceeds			$ 57,000
Equity value					$ 275,573
Par value per share					$ 0.05
Calyxt Inc [member]
Statement [Line Items]
Ordinary shares issued	3,750,000		4,057,500
Selling price per common share	$ 4		$ 15
Common stock for exercising underwriters' option			457,500
Gross proceeds	$ 15,000		$ 57,000
Underwriting discounts and commissions			3,200
Offering expense			$ 700
Number of stock options exercised				592,342
Stock options exercised, value		$ 2,400
Par value per share	$ 4		$ 15
Proportion of ownership interest in subsidiary					64.70%
Calyxt Inc [member] | Cellectis [member]
Statement [Line Items]
Purchase of common stock			550,000
Equity value	$ 5,000
Purchase of common shares	1,250,000	63,175
Purchase of common stock, value	$ 14,000
Purchase of common shares price per share		$ 19.49
Purchase of common stock, value		$ 1,200	$ 8,300

The Company

The Company	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
The Company	Note 1. The Company Cellectis S.A. (hereinafter “Cellectis” or “we”) is a limited liability company (“société anonyme”) registered and domiciled in Paris, France. We are a clinical-stage biotechnological company, employing our core proprietary technologies to develop best-in-class T-cells T-cells, Cellectis S.A., Cellectis, Inc., Cellectis Biologics Inc. (which was incorporated on January 18, 2019) and Calyxt, Inc. are sometimes referred to as a consolidated group of companies as the “Group.” COVID-19 As previously reported, while implementing health and safety measures, we have continued to advance our proprietary allogeneic CAR T-cell MELANI-01 AMELI-01, BALLI-01 MELANI-01 In addition, construction is now complete for our raw materials manufacturing facility in Paris, and our commercial manufacturing facility in Raleigh, North Carolina remains on track with production expected to commence in 2021. With respect to the five out-licensed follow-up Nevertheless, the COVID-19 T-cell follow-up COVID-19 COVID-19 At Calyxt, during 2020, supply chain disruptions did not have a material impact on Calyxt’s operations. However, a resurgence of the COVID-19 The overall impact to Cellectis’ and Calyxt’s businesses will be dependent on future developments, which are highly uncertain and difficult to predict.

Accounting principles

Accounting principles	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Accounting principles	Note 2. Accounting principles 2.1 Basis for preparation The Consolidated Financial Statements of Cellectis as of and for the year ended December 31, 2020 were approved by our Board of Directors on March 4, 2021. Our Consolidated Financial Statements are presented in U.S. dollars. See Note 2.3. The Consolidated Financial Statements have been prepared in accordance with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”) and in conformity with IFRS as endorsed by the European Union. The Consolidated Financial Statements have been prepared using the historical cost measurement basis except for certain assets and liabilities that are measured at fair value in accordance with IFRS. IFRS include International Financial Reporting Standards (“IFRS”), International Accounting Standards (“the IAS”), as well as the interpretations issued by the Standards Interpretation Committee (“the SIC”), and the International Financial Reporting Interpretations Committee (“IFRIC”). The significant accounting methods used to prepare the Consolidated Financial Statements are described below. Application of new or amended standards or new amendments The following pronouncements and related amendments have been adopted by us from January 1, 2020 but had no significant impact on the Consolidated Financial Statements: • Amendments to References to the Conceptual Framework in IFRS Standards (Effective for the accounting periods as of January 1, 2020) • Amendment to IFRS 3 “Business Combinations” (Effective for the accounting periods as of January 1, 2020) • Amendments to IAS 1 “Presentation of financial statements” and IAS 8 “Accounting policies, changes in accounting estimates and errors” (Effective for the accounting periods as of January 1, 2020) • Amendments to IFRS 9 “Financial instruments”, IAS 39 “Financial instruments: Recognition and Measurement” and IFRS 7 “Financial instruments: Disclosures” (Effective for the accounting periods as of January 1, 2020)—Interest Rate Benchmark Reform • On May 28, 2020, the IASB issued “Covid-19-Related Covid-19 Standards, interpretations and amendments issued but not yet effective The following pronouncements and related amendments are applicable for first quarter accounting periods beginning after January 1, 2021. We do not anticipate that the adoption of these pronouncements and amendments will have a material impact on our results of operations, financial position or cash flows. • IFRS 17 “Insurance Contracts” (Effective for accounting periods beginning after January 1, 2023 and not yet adopted by the European Union) • Amendments to IAS 37 – Onerous Contracts: Cost of Fulfilling a Contract (Effective for the accounting periods as of January 1, 2022) • Amendments to IAS 37 – Onerous Contracts: Cost of Fulfilling a Contract (Effective for the accounting periods as of January 1, 2022) • Amendments to IAS 16 – Property, Plant and Equipment: Proceeds before Intended Use (Effective for the accounting periods as of January 1, 2022) • Amendments to IFRS 3 – Reference to the Conceptual Framework (Effective for the accounting periods as of January 1, 2022) • Amendments to IFRS 9, IAS 39, IFRS 7, IFRS 4 and IFRS 16 – Interest Rate Benchmark Reform – Phase 2 (Effective for the accounting periods as of January 1, 2021) 2.2 IFRS16 application Since January 1, 2019, Cellectis has applied the new standard IFRS 16 “Leases”. Under this standard, a financial asset and a financial liability are recognized for Group leases that meet the standard’s criteria. The financial statements for prior periods have not been restated in accordance with the transition options of IFRS 16 elected by the Group since Cellectis has applied the modified retrospective approach. The Group uses the two capitalization exemptions provided by the standard: • lease contracts with a duration of less than 12 months; and • lease contracts for which the underlying asset has a low value, which has been defined by the Group to be below $5,000. The Group has also applied the following practical expedients at the transition date: • exclusion of initial direct costs from the measurement of the right-of-use • accounting for leases for which the lease term ends within 12 months of the date of initial application as short-term leases i.e. accounting for leases expenses in Profit and loss account; and • the carrying amount of the right-of-use The following discount rates have been applied: • building rental in Paris, France (discounting rate 2%), building rental in Roseville, Minnesota, USA and Raleigh, North Carolina, USA (discounting rate of 8%), building rental in New York, New York, USA (discounting rate of 4.4%), and equipment rental (discounting rate 1%). The main changes introduced by IFRS 16 are the following: Capitalization of the right-of-use Identified lease contracts mainly concern Cellectis’ Headquarters and R&D buildings in Paris, New York and Raleigh, North Carolina, USA and Calyxt’s Headquarters and its production and storage areas in Roseville, Minnesota, USA. For purposes of IFRS 16, the lease term reflects the Group’s reasonable expectation of the period during which the underlying asset will be used. The discount rate used to calculate the lease debt has been determined, for each portfolio of assets, according to the incremental borrowing rate at the transition date. The sale and lease-back agreement entered into by Calyxt in the third quarter of 2017 has a defined lease term and was classified as an operating lease agreement under IAS 17. According to IFRS 16, this lease receives the standard accounting treatment for operating leases existing at the date of initial application and the value of the right-of-use Accounting for the other assets leases: The main lease contracts identified correspond to office and laboratory equipment. 2.3 Currency of the financial statements The Consolidated Financial Statements are presented in U.S. dollars, which differs from the functional currency of Cellectis, which is the euro. All financial information (unless indicated otherwise) is presented in thousands of U.S. dollars. The statements of financial position of consolidated entities having a functional currency different from the U.S. dollar are translated into U.S. dollars at the closing exchange rate (spot exchange rate at the statement of financial position date) and the statements of operations, statements of comprehensive income (loss) and statements of cash flow of such consolidated entities are translated at the average period to date exchange rate. The resulting translation adjustments are included in equity under the caption “Currency Translation Adjustments” in the Consolidated Statements of Changes in Shareholders’ Equity. 2.4 Basis of consolidation Going concern The consolidated financial statements were prepared on a going concern basis. With cash and cash equivalents of $241,148 thousand as of December 31, 2020, the Company believes it has sufficient resources to continue operating for at least twelve months following the consolidated financial statements’ publication. Accounting policy We control all the legal entities included in the consolidation. An investor controls an investee when the investor is exposed to variable returns from its involvement with the investee, and has the ability to affect those returns through its power over the investee. Control requires power, exposure to variability of returns and a linkage between the two. To have power, the investor needs to have existing rights that give it the current ability to direct the relevant activities that significantly affect the investee’s returns. In order to ascertain control, potential voting rights which are substantial are taken into consideration. Consolidation of a subsidiary begins when the Group obtains control over the subsidiary and ceases when the Group loses control of the subsidiary. All intra-group assets and liabilities, equity, income, expenses and cash flows relating to transactions between members of the Group are eliminated in full consolidation. Consolidated entities For the year ended December 31, 2020, the consolidated group of companies (sometimes referred to as the “Group”) includes Cellectis S.A., Cellectis, Inc., Cellectis Biologics Inc., which was incorporated on January 18, 2019, and Calyxt. As of December 31, 2020, Cellectis S.A. owns 100% of Cellectis, Inc., which owns 100% of Cellectis Biologics, Inc., and approximately 64.7% of Calyxt’s outstanding shares of common stock. As of December 31, 2019, Cellectis S.A. owned 100% of Cellectis, Inc. and approximately 68.9% of Calyxt’s outstanding shares of common stock. Until July 25, 2017, Cellectis S.A. fully owned Calyxt. On July 25, 2017, Calyxt closed its IPO with $64.4 million in gross proceeds to Calyxt from the sale of 8,050,000 shares at $8 per share, including the full exercise of the underwriter’s over-allotment option and Cellectis’ purchase of $20.0 million of shares in the IPO. On May 22, 2018, Calyxt completed a follow-on follow-on follow-on SEC-registered, Non-controlling Non-controlling non-controlling follow-on 2.5 Foreign currency Foreign currency transactions and balances Significant transactions in foreign currencies are translated into the respective functional currencies at the exchange rates effective at the transaction dates, otherwise the average rate of the previous month is used for non-significant The resulting exchange gains or losses are recorded in the consolidated statements of operations in financial gain (loss). Foreign currency translation The assets and liabilities of foreign operations having a functional currency different from the euro are translated into euros at the period end exchange rate. The income and expenses of foreign operations are translated into euros using the average exchange rate for the reporting period. Gains and losses arising from currency translation are recognized in other comprehensive loss. Consolidated financial statements are then converted into dollars using the method described in Note 2.3. The difference in effect of exchange rate changes on cash and cash equivalents between the statements of consolidated operations and consolidated cash flows is mainly explained by the following elements: • the differential between the average exchange rate and the period end rates applied to the cash flows of the period; • the differential between the opening exchange rates and the period end exchanges rate applied on our opening cash and cash equivalents balance denominated in dollars; and • the foreign exchange rate impact of the conversion of the financial statements of our US subsidiaries. 2.6 Use of judgment, estimates and assumptions The preparation of these consolidated financial statements requires management to make judgments, estimates and assumptions that affect the reported amounts of revenues, expenses, assets and liabilities, and the accompanying disclosures, including the disclosure of contingent liabilities. Actual amounts may differ from those estimates. The Group’s exposure to risks and uncertainties is disclosed in Note 8.3: Financial instruments risk management and policies. Estimates and assumptions The key assumptions concerning the future and other key sources of estimation uncertainty at the period end date, that have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year, are described below. The Group based its assumptions and estimates on parameters available when the consolidated financial statements were prepared. Existing circumstances and assumptions about future developments, however, may change due to market changes or circumstances arising that are beyond the control of the Group. Such changes are reflected in the assumptions when they occur. • Revenue recognition – Note 3.1 • Share-based payments – Note 16 • Provisions for risks and charges – Note 18 • Right-of-use

Information concerning the Grou

Information concerning the Group's Consolidated Operations	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Information concerning the Group's Consolidated Operations	Note 3. Information concerning the Group’s Consolidated Operations 3.1 Revenues and other income Accounting policies Collaboration agreements and licenses Under IFRS 15, “Revenue from contracts with customers”, revenue is recognized when Cellectis satisfies a performance obligation by transferring a distinct good or service (or a distinct bundle of goods and or/ services) to a customer, i.e. when the customer obtains control of these goods or services. We have entered into certain research and development collaboration agreements that consist of the licensing of rights to technology, research and development programs, research and development cost reimbursements and royalties. We have analyzed the agreements to identify the separate performance obligations. These collaboration agreements may generate cash flows through non-refundable upfront payments related to the licensing of rights to technology and research and development programs, milestone payments research and development cost reimbursements and royalties. Licensing of rights to technology pursuant to non-cancelable, non-refundable fixed and upfront fee arrangements are recognized when such technology is delivered to the co-contracting party and our exclusive rights to access the technology have stopped. Up-front Research and development costs reimbursements are recognized on a time and material basis over the length of the specific research and development project. Milestone payments represent variable consideration, the receipt of which is dependent upon the achievement of certain scientific, regulatory, or commercial milestones. Such payments are considered variable consideration. We recognize milestone payments when it is highly probable that any revenue recognized will not be subsequently reversed. This includes consideration of whether the performance obligation is achieved and may be when the triggering event has occurred, depending on the nature of the triggering event, there are no further contingencies or services to be provided with respect to that event, and the co-contracting Royalty revenues arise from our contractual entitlement to receive a percentage of product sales achieved by co-contracting In addition, we license our technology to other third parties and revenues are recognized ratably over the period of the license agreements. Sales of products and services Revenues on sales of products are recognized at the point in time once the control over the delivered products is transferred to the customer, which is based on shipping terms. Sales include shipping and handling charges if billed to the customer and are reported net of trade promotion and other costs, including estimated allowances for returns, unsalable product and prompt pay discounts. Sales, use, value-added and other excise taxes are not recognized in revenue. Trade promotions are recorded based on estimated participation and performance levels for offered programs at the time of sale. We generally do not allow a right of return. In certain instances, we may sell grain to a processor with a commitment to repurchase any soybean meal resulting from their grain crushing activity with a single net cash settlement occurring between the parties. In those instances, we recognize revenue from the sale of grain in the amount of the final net cash settlement with the processor. We also recognize revenue on our sale of the meal to our customers in accordance with our previously disclosed revenue recognition accounting policies. Costs are ascribed to grain and meal sold pursuant to the agreement with the processor. In certain instances, we may sell grain to a processor and subsequent to the sale they will utilize our storage facility to hold the grain until such time they request it be delivered. We are responsible for all handling charges and delivery activities. In those instances, we recognize revenue from the sale of grain to the processor and concurrently accrue all estimated future storage, handling associated with that sale, except delivery costs considered as future revenues and prepaid expenses. We also offer research services, which revenue is recognized over time, as the customer receives the benefits of the services. Research Tax Credit The main Research Tax Credit from which we benefit is the Cr é dit d ’ Imp ô t Recherche, medium-sized We apply for CIR for research expenditures incurred in each fiscal year and recognize the amount claimed in the line item “Other income” in the same fiscal year. Research tax credit is subject to audit of tax authorities. When tax authorities’ payment related to CIR is late, default interests are applied and are recognized in “other income”. Details of revenues and other income Revenues by country of origin and other income For the year ended December 31, 2018 2019 2020 From France 12,495 7,896 51,057 From USA 236 7,294 22,892 Revenues 12,731 15,190 73,949 Research tax credit 8,561 7,800 8,433 Subsidies and other 140 — 74 Other income 8,701 7,800 8,507 Total revenues and other income 21,432 22,990 82,456 For the years ended December 31, 2020, 2019 and 2018, the revenue from France was generated by Cellectis S.A. For the years ended December 31, 2020, 2019 and 2018, the revenue from USA was generated by Calyxt. Revenues by nature For the year ended December 31, 2018 2019 2020 $ in thousands Recognition of previously deferred upfront payments 7,114 — 20,291 Other revenues 3,383 6,055 28,532 Collaboration agreements 10,497 6,055 48,823 Licenses 2,142 1,762 2,123 Products & services 92 7,373 23,003 Total revenues 12,731 15,190 73,949 Recognition of previously deferred upfront payments mainly reflects the recognition of $19.4 million of deferred upfront and milestone payments on released targets, which is associated with the amendment to the License, Development and Commercialization Agreement between Les Laboratoires Servier and Institut de Recherches Internationales Servier (“Servier”) and Cellectis dated March 4, 2020 (the “Servier Amendment”). In 2018, other revenues primarily consisted of research and development cost reimbursement. In addition to the cost reimbursement, for the year ended December 31, 2019, other revenues also include the recognition of a $5.0 million milestone which is associated with the initiation of the study of ALLO-715 T-cell UCART19/ALLO-501 and ALLO-501A. For the years ended December 31, 2020, 2019 and 2018, revenues related to licenses includes royalties received under our various license agreements. For the year ended December 31, 2020, products and services revenues mainly include the revenues of plants activities which in 2020 are primarily attributable to the commercialization of Calyxt’s first products, high oleic soybean oil and meal for $22.9 million. Entity-wide disclosures: In 2020, two clients represent more than 10% of the total revenue: Client A with 64% and Client B with 25%. In 2019, two clients represent more than 10% of the total revenue: Client A with 36% and Client B with 28%. In 2018, two clients represent more than 10% of the total revenue: Client A with 55% and Client B with 21%. 3.2 Operating expenses Accounting policies Prior to 2019, cost of goods sold represented immaterial costs associated with Calyxt’s out-licensing osts incurred at Calyxt associate Royalty expenses correspond to costs from license agreements that we entered into to obtain access to technology that we use in our product development efforts. Depending on the contractual provisions, expenses are based either on a percentage of revenue generated by using the patents based on fixed annual royalties or conditioned by milestones. Research and development expenses include employee-related costs, laboratory consumables, materials supplies and facility costs, as well as fees paid to non-employees Selling, general and administrative expenses consist primarily of employee-related expenses for executive, business development, intellectual property, finance, legal and human resource functions. Administrative expenses also include facility-related costs and service fees, other professional services, recruiting fees and expenses associated with maintaining patents. We classify a portion of personnel and other costs related to information technology, human resources, business development, legal, intellectual property and general management in research and development expenses based on the time that each employee or person spent contributing to research and development activities versus sales, general and administrative activities. Details of operating expenses by nature For the year ended December 31, 2018 2019 2020 $ in thousands Cost of revenue Cost of goods sold (1) — (9,280 ) (34,168 ) Royalty expenses (2,739 ) (2,112 ) (2,107 ) Cost of revenue (2,739 ) (11,392 ) (36,275 ) For the year ended December 31, 2018 2019 2020 $ in thousands Research and development expenses Wages and salaries (16,452 ) (21,294 ) (29,818 ) Social charges on stock option grants (99 ) (1,357 ) (56 ) Non-cash (18,057 ) (12,260 ) (8,029 ) Personnel expenses (34,608 ) (34,911 ) (37,903 ) Purchases and external expenses (40,458 ) (49,251 ) (41,270 ) Other (1,501 ) (7,880 ) (7,777 ) Total research and development expenses (76,567 ) (92,042 ) (86,950 ) For the year ended December 31, 2018 2019 2020 $ in thousands Selling, general and administrative expenses Wages and salaries (11,373 ) (12,822 ) (15,794 ) Social charges on stock option grants (29 ) (491 ) (23 ) Non-cash (19,161 ) (14,621 ) (8,707 ) Personnel expenses (30,563 ) (27,934 ) (24,524 ) Purchases and external expenses (14,251 ) (11,431 ) (15,358 ) Other (2,433 ) (3,652 ) (4,319 ) Total selling, general and administrative expenses (47,248 ) (43,017 ) (44,201 ) For the year ended December 31, 2018 2019 2020 $ in thousands Personnel expenses Wages and salaries (27,825 ) (34,116 ) (45,612 ) Social charges on free shares and stock option grants (128 ) (1,848 ) (79 ) Non-cash (37,218 ) (26,881 ) (16,736 ) Total personnel expenses (65,171 ) (62,845 ) (62,427 ) (1) Corresponds to the Calyxt costs of goods sold decreased by transportation costs related to Archer Daniels Midland (ADM) sales, considered as prepaid expenses under IFRS 15. 3.3 Financial income and expenses Accounting policies Financial income and financial expense include, in particular, the following: • Interest income from savings accounts and fixed term bank deposits; • Interest expense from leases; • Foreign exchange gain (loss) from transactions in foreign currencies; and • Other financial income and expenses, mainly derived from fair value adjustments related to our financial assets and derivative instruments. Details of financial income and expenses For the year ended December 31, 2018 2019 2020 Interest income 6,787 6,985 1,949 Foreign exchange gain 13,597 4,481 3,155 Other financial revenues 188 505 364 Total financial revenues 20,572 11,971 5,468 Interest expenses (39 ) (3 ) (43 ) Interest expenses for leases (7 ) (2,603 ) (3,557 ) Foreign exchange loss (3,090 ) (671 ) (13,885 ) Other financial expenses (677 ) (354 ) (29 ) Total financial expenses (3,813 ) (3,631 ) (17,514 ) Total 16,758 8,340 (12,046 ) The decrease in financial income of $6.5 million between 2019 and 2020 was mainly attributable to a decrease of the foreign exchange gain of $1.3 million (from a $4.5 million gain in 2019 to a $3.2 million gain in 2020), to the decrease of interest received from financial investment of $5.0 million and to the decrease in fair value adjustment for $0.2 million in relation with the decrease in interest rates compared to 2019. The increase in financial expenses of $13.9 million between 2019 and 2020 was mainly attributable to $13.2 million increase in foreign exchange loss (from a $0.7 million loss in 2019 to a $13.9 million loss in 2020), the increase in financial expenses related to the increase in lease debt for $1.0 million and other immaterial variances for $0.3 million. The decrease in financial income and expenses between 2018 and 2019 of $8.4 million was mainly attributable to the decrease in net foreign exchange gain ($6.7 million), and the increase in interest expenses related to IFRS 16 application ($2.6 million), partly offset by the increase of foreign exchange derivatives fair value adjustment ($0.6 million), included in other financial revenues and expenses and the increase in net interest income ($0.2 million) and other immaterial variances for $0.1 million. 3.4 Income tax Accounting policies Income tax (expense or income) comprises current tax expense (income) and deferred tax expense (income). Deferred taxes are recognized for all the temporary differences arising from the difference between the tax basis and the accounting basis of assets and liabilities. Tax losses that can be carried forward or backward may also be recognized as deferred tax assets. Tax rates that have been enacted as of the closing date are utilized to determine deferred tax. Deferred tax assets are recognized only to the extent that it is likely that future profits will be sufficient to recover them. We have not recorded deferred tax assets or liabilities in the statements of financial position. Tax proof For the year ended December 31, 2018 2019 2020 in thousands Income (loss) before taxes from continuing operations (88,333 ) (115,212 ) (97,483 ) Theoretical group tax rate 23.66 % 25.35 % 24.88 % Theoretical tax benefit (expense) 20,901 29,208 24,254 Increase/ decrease in tax benefit arising from: Permanent differences 832 (1,131 ) (1,141 ) Research tax credit 2,079 2,786 3,245 Share-based compensation & other IFRS adjustments (8,065 ) (7,828 ) (4,198 ) Non recognition of deferred tax assets related to tax losses and temporary differences (15,652 ) (23,079 ) (22,159 ) Other differences (95 ) 43 0 Effective tax expense — — — Effective tax rate 0.00 % 0.00 % 0.00 % Deferred tax assets and liabilities As of December 31, 2018 2019 2020 $ in thousands Credits and net operating loss carryforwards 65,555 102,112 141,954 Pension commitments 569 714 1,003 Leases (4 ) 47 319 Impairment of assets 10 1 1 Revenue recognition 200 197 (491 ) Other 491 284 1,308 Total unrecognized deferred tax assets, net (66,823 ) (103,354 ) (144,095 ) We have cumulative tax loss carryforwards for the French entity of the Group totaling $325 tax The cumulative tax loss carryforwards for the U.S. entities of the Group totaled $160 Calyxt’s carryforward periods are as follows: $64.0 million do not expire; zero expire in 2019 and 2020; and $41.9 million expire in 2032 and beyond. 3.5 Reportable segments Accounting policies Reportable segments are identified as components of the Group that have discrete financial information available for evaluation by the Chief Operating Decision Maker (“CODM”), for purposes of performance assessment and resource allocation. Cellectis’ CODM is composed of: • The Chief Executive Officer; • The Executive Vice President Strategic Initiatives; • The Executive Vice President Global Quality; • The Senior Vice President Europe Technical Operations (from August 6, 2020); • The Senior Vice President of US Manufacturing (from August 6, 2020); • The Chief Scientific Officer; • The Chief Financial Officer; • The General Counsel; • The Chief Business Officer; • The Chief Regulatory & Compliance Officer; • The Chief Medical Officer (from April 13, 2020); and • The Chief Human Resources Officer (from November 6, 2020). We view our operations and manage our business in two operating and reportable segments that are engaged in the following activities: • Therapeutics: • Plants: There are inter-segment transactions between the two reportable segments, including allocation of corporate general and administrative expenses by Cellectis S.A. and allocation of research and development expenses to the reportable segments. With respect to corporate general and administrative expenses, Cellectis S.A. has provided Calyxt, with general sales and administrative functions, accounting and finance functions, investor relations, intellectual property, legal advice, human resources, communication and information technology under a Management Services Agreement. Effective with the end of the third quarter 2019, Calyxt has internalized nearly all of the services previously provided by Cellectis under this agreement. Under the Management Services Agreement, Cellectis S.A. charges Calyxt, in euros at cost plus a mark-up 12-month The intersegment revenues represent the transactions between segments. Intra-segment transactions are eliminated within a segment’s results and intersegment transactions are eliminated in consolidation as well as in key performance indicators by reportable segment. Information related to each reportable segment is set out below. Segment revenues and other income, Research and development expenses, Selling, general and administrative expenses, and Cost of revenue and other operating income and expenses, and Adjusted net income (loss) attributable to shareholders of Cellectis (which does not include non-cash Adjusted Net Income (Loss) attributable to shareholders of Cellectis S.A. is not a measure calculated in accordance with IFRS. Because Adjusted Net Income (Loss) attributable to shareholders of Cellectis excludes Non-cash non-cash The net income (loss) includes the impact of the operations between segments while the intra-segment operations are eliminated. Details of key performance indicators by reportable segment For the year ended December 31, 2018 For the year ended December 31, 2019 For the year ended December 31, 2020 ( ) Plants Therapeutics Total Plants Therapeutics Total Plants Therapeutics Total External revenues 236 12,495 12,731 7,294 7,896 15,190 22,892 51,057 73,949 External other income 178 8,523 8,701 — 7,800 7,800 — 8,507 8,507 External revenues and other income 414 21,018 21,432 7,294 15,696 22,990 22,892 59,564 82,456 Cost of revenue (595 ) (2,144 ) (2,739 ) (9,275 ) (2,117 ) (11,392 ) (34,324 ) (1,951 ) (36,275 ) Research and development expenses (8,638 ) (67,929 ) (76,567 ) (12,390 ) (79,652 ) (92,042 ) (9,903 ) (77,048 ) (86,951 ) Selling, general and administrative expenses (21,067 ) (26,180 ) (47,248 ) (26,090 ) (16,927 ) (43,017 ) (21,688 ) (22,513 ) (44,201 ) Other operating income and expenses (50 ) 81 31 25 (116 ) (91 ) (103 ) (363 ) (466 ) Total operating expenses (30,351 ) (96,172 ) (126,523 ) (47,730 ) (98,812 ) (146,542 ) (66,018 ) (101,875 ) (167,893 ) Operating income (loss) before tax (29,937 ) (75,154 ) (105,091 ) (40,436 ) (83,116 ) (123,552 ) (43,126 ) (42,311 ) (85,437 ) Financial gain (loss) 1,420 15,339 16,758 294 8,045 8,340 (776 ) (11,270 ) (12,046 ) Net income (loss) (28,517 ) (59,816 ) (88,333 ) (40,142 ) (75,071 ) (115,212 ) (43,902 ) (53,581 ) (97,483 ) Non controlling interests 9,640 — 9,640 13,121 — 13,121 16,409 — 16,409 Net income (loss) attributable to shareholders of Cellectis (18,877 ) (59,816 ) (78,693 ) (27,021 ) (75,071 ) (102,091 ) (27,493 ) (53,581 ) (81,074 ) R&D non-cash 838 16,852 17,689 1,619 10,010 11,629 801 6,790 7,591 SG&A non-cash 5,218 11,655 16,873 6,673 4,940 11,613 3,536 3,238 6,774 Adjustment of share-based compensation attributable to shareholders of Cellectis 6,056 28,507 34,563 8,292 14,950 23,242 4,337 10,028 14,365 Adjusted net income (loss) attributable to shareholders of Cellectis (12,821 ) (31,309 ) (44,130 ) (18,729 ) (60,121 ) (78,849 ) (23,156 ) (43,553 ) (66,709 ) Depreciation and amortization (637 ) (1,740 ) (2,377 ) (1,233 ) (5,642 ) (6,875 ) (1,869 ) (7,950 ) (9,819 ) Additions to tangible and intangible assets 1,871 3,040 4,911 2,998 14,668 17,666 1,786 48,813 50,599

Impairment tests

Impairment tests	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Impairment tests	Note 4. Impairment tests Accounting policy Amortizable intangible assets, depreciable tangible assets and right-of-use Our cash-generating units (“CGUs”) correspond to the operating/reportable segments: Therapeutics and Plants. Results of impairment test No indicator of impairment has been identified for any intangible or tangible assets in either of the CGUs for the years ended December 31, 2018, 2019 or 2020.

Intangible assets

Intangible assets	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Intangible assets	Note 5. Intangible assets Accounting policy Capitalization of development expenses In accordance with IAS 38 Intangible Assets • technical feasibility necessary for the completion of the development project; • intention on our part to complete the project and to utilize it; • capacity to utilize the intangible asset; • proof of the probability of future economic benefits associated with the asset; • availability of the technical, financial, and other resources for completing the project; and • reliable evaluation of the development expenses. Other intangible assets The other intangible assets we acquired with definite useful lives are recognized at cost less accumulated amortization and impairment. Amortization expense is recorded on a straight-line basis over the estimated useful lives of the intangible assets, in the line Research and Development expenses or Selling, general and administrative expenses of the Statement of Consolidated Operations, depending on the use of the related asset. The estimated useful lives are as follows: • Software: from 1 year to 3 years; • Patents: amortized from acquisition until legal protection expires, maximum of 20 years. Details of intangible assets $ in thousands Software and Patents Assets under construction Total Net book value as of January 1, 2018 811 619 1,431 Additions to intangible assets 14 103 117 Disposal of intangible assets (7 ) — (7 ) Reclassification 6 — 6 Depreciation expense (217 ) — (217 ) Translation adjustments (30 ) (31 ) (61 ) Net book value as of December 31, 2018 577 691 1,268 Gross value at end of period 2,454 691 3,146 Accumulated depreciation and impairment at end of period (1,878 ) — (1,878 ) Net book value as of January 1, 2019 577 691 1,268 Additions to intangible assets 84 (2 ) 82 Disposal of intangible assets (50 ) — (50 ) Reclassification 6 — 6 Depreciation expense (174 ) — (174 ) Translation adjustments (12 ) (12 ) (24 ) Net book value as of December 31, 2019 431 677 1,108 Gross value at end of period 2,448 677 3,125 Accumulated depreciation and impairment at end of period (2,017 ) — (2,017 ) Net book value as of January 1, 2020 431 677 1,108 Additions to intangible assets 558 (41 ) 517 Disposal of intangible assets — — — Reclassification 76 — 76 Depreciation expense (206 ) — (206 ) Translation adjustments 30 59 89 Net book value as of December 31, 2020 889 695 1,584 Gross value at end of period 3,309 695 4,004 Accumulated depreciation and impairment at end of period (2,419 ) — (2,419 ) Intangible assets mainly consist of electroporation technology patents acquired in 2011. The 2018, 2019 and 2020 additions in intangible assets under construction corresponds to the internal development of existing technology.

Right-of-use assets

Right-of-use assets	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Right-of-use assets	Note 6 Right-of-use Accounting policy Lease contracts recognition Lease contracts, as defined by IFRS 16 “Leases”, are recorded in the statement of consolidated financial position, which leads to the recognition of: • an asset representing a right of use of the asset leased during the lease term of the contract “right-of-use”; • a liability related to the payment obligation “lease debt”. Measurement of the right-of At the commencement date, the right-of-use • the amount of the initial measurement of the lease liability, to which is added, if applicable, any lease payments made at or before the commencement date, less any lease incentives received; • where relevant, any initial direct costs incurred by the lessee for the conclusion of the contract. These are incremental costs which would not have been incurred if the contract had not been concluded; and • estimated costs for restoration of the leased asset according to the terms of the contract. Following the initial recognition, the right-of-use Measurement of the lease liability At the commencement date, the lease liability is recognized for an amount equal to the present value of the lease payments over the lease term. Amounts involved in the measurement of the lease liability are: • fixed payments (including in-substance in-substance • variable lease payments that depend on an index or a rate, initially measured using the index or the rate in force at the lease commencement date; amounts expected to be payable by the lessee under residual value guarantees; and • payments of penalties for terminating the lease, if the lease term reflects the lessee exercising an option to terminate the lease. The lease liability is subsequently measured based on a process similar to the amortized cost method using the discount rate: • the liability is increased by the accrued interests resulting from the discounting of the lease liability, at the beginning of the lease period; and • payments made are deducted. The interest cost for the period as well as variable payments, not taken into account in the initial measurement of the lease liability and incurred over the relevant period are recognized as costs. In addition, the lease liability may be remeasured in the following situations: • the occurrence of a change in the lease term or a modification related to the assessment of the reasonably certain nature (or not) of the exercise of an option, • a remeasurement linked to residual value guarantees, • the occurrence of an adjustment to the rates and indices according to which the rents are calculated when rent adjustments occur. COVID-19-Related On May 28, 2020, the IASB issued “Covid-19-Related Covid-19 The amount recognised in profit or loss for the reporting period to reflect changes in lease payments that arise from rent concessions to which the Group has applied the practical expedient in IFRS 16.46A is immaterial. Main contracts applicable Based on its analysis, the Group has identified lease contracts according to the standard concerning office buildings, laboratories, production facilities and storage facilities. For purposes of IFRS 16, the lease term reflects the Group’s reasonable expectation of the period during which the underlying asset will be used. The discount rate used to calculate the lease debt is determined, for each portfolio of assets, according to the incremental borrowing rate at the contract date. The incremental borrowing rate is the rate of interest that a lessee would have to pay to borrow over a similar term, and with a similar security, the funds necessary to obtain an asset of a similar value to the right-of-use The rental charges relating to short terms and low value lease remains classified as leases expenses in operating expenses and are immaterial. Details of Right-of-use IFRS 16 “Leases” was applicable for annual periods beginning on or after January 1, 2019. The consequence of the application of this standard is to recognize a right of use and lease liability on the balance sheet. For the leaseback on Calyxt Headquarters, according to IFRS 16, the value of the right-of-use The breakdown of right-of-use Building lease Office and Total $ in thousands Net book value as of January 1, 2019 36,061 1,508 37,569 Additions 11,357 1,516 12,873 Depreciation expense (4,058 ) (520 ) (4,578 ) Translation adjustments (248 ) (4 ) (252 ) Net book value as of December 31, 2019 43,112 2,500 45,612 Gross value at end of period 47,175 3,153 50,328 Accumulated depreciation at end of period (4,063 ) (653 ) (4,716 ) Net book value as of January 1, 2020 43,112 2,500 45,612 Additions 24,719 8,369 33,088 Depreciation expense (4,904 ) (1,568 ) (6,472 ) Translation adjustments 1,699 (82 ) 1,617 Net book value as of December 31, 2020 64,626 9,219 73,845 Gross value at end of period 73,878 11,511 85,389 Accumulated depreciation at end of period (9,252 ) (2,292 ) (11,544 )

Property, plant and equipment

Property, plant and equipment	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Property, plant and equipment	Note 7. Property, plant and equipment Accounting policy Property, plant and equipment are recognized at acquisition cost less accumulated depreciation and any impairment losses. Acquisition costs include expenditures that are directly attributable to the acquisition of the asset and costs to ready it for use. Depreciation is expensed on a straight-line basis over the estimated useful lives of the assets. If components of property, plant and equipment have different useful lives, they are accounted for separately. The estimated useful lives are as follows: • Buildings and other outside improvements 10-20 • Leasehold improvements 5-10 • Office furniture 10 years • Laboratory equipment 3-10 • Office equipment 5 years • IT equipment 3 years Depreciation methods, useful lives and residual values are reviewed at each reporting date and adjusted, if appropriate. Any gain or loss on disposal of an item of property, plants and equipment is determined by comparing the proceeds from disposal with the carrying amount of the item. The net amount is recognized in the statement of consolidated operations under the line item “Other operating income and expenses.” Before IFRS 16 adoption as of January 1, 2019, payments made under operating leases were expensed on a straight-line basis over the term of the lease. Lease incentives received were recognized as an integral part of the total lease expense, over the term of the lease. If, according to the terms of a lease, it appeared that substantially all the risks and rewards incidental to ownership were transferred from the lessor to the lessee, the associated leased assets were initially recognized as an asset at the lower of their fair value and the present value of the minimum lease payments and subsequently depreciated or impaired, as necessary. Finance lease assets were transferred to Right-of-use “non-current Details of property, plant and equipment Lands and Technical Fixtures, Assets under Total $ in thousands Net book value as of January 1, 2018 3,159 2,505 753 809 7,226 Additions to tangible assets 879 1,622 1,820 1,942 6,263 Disposal of tangible assets — (49 ) (690 ) (426 ) (1,164 ) Reclassification 39 216 793 (1,053 ) (6 ) Depreciation expense (758 ) (854 ) (478 ) — (2,091 ) Translation adjustments (90 ) (46 ) (27 ) (25 ) (188 ) Net book value as of December 31, 2018 3,229 3,393 2,172 1,247 10,041 Gross value at end of period 7,604 13,297 3,215 2,045 26,160 Accumulated depreciation and impairment at end of period (4,375 ) (9,903 ) (1,043 ) (798 ) (16,119 ) Net book value as of January 1, 2019 3,229 2,084 2,172 1,247 8,732 Additions to tangible assets 318 374 329 16,563 17,584 Disposal of tangible assets — (10 ) (1 ) (419 ) (430 ) Reclassification 15 1,974 630 (2,624 ) (5 ) Depreciation expense (192 ) (1,247 ) (684 ) — (2,123 ) Translation adjustments (40 ) (15 ) (11 ) 20 (46 ) Net book value as of December 31, 2019 3,330 3,160 2,435 14,787 23,712 Gross value at end of period 7,833 13,962 4,149 15,585 41,529 Accumulated depreciation and impairment at end of period (4,503 ) (10,802 ) (1,714 ) (798 ) (17,817 ) Net book value as of January 1, 2020 3,330 3,160 2,435 14,787 23,712 Additions to tangible assets 5,248 2,034 854 41,946 50,082 Disposal of tangible assets 4 (122 ) — — (118 ) Reclassification 8,258 692 670 (9,696 ) (76 ) Depreciation expense (817 ) (1,464 ) (861 ) — (3,141 ) Translation adjustments 742 136 73 264 1,215 Net book value as of December 31, 2020 16,765 4,436 3,171 47,301 71,673 Gross value at end of period 22,518 17,381 5,843 47,301 93,043 Accumulated depreciation and impairment at end of period (5,752 ) (12,946 ) (2,672 ) (0 ) (21,370 ) * See note 2.2 on IFRS16 application No assets have been pledged as security for financial liabilities. There is no restriction on title of property, plant and equipment. In 2017, Calyxt entered into a transaction whereby it sold a certain land and building (with a total net book value of $9.2 million), which was considered a sale under applicable accounting guidance and then entered into an operating lease for this property. The sale and lease-back agreement has a defined lease term and was classified as an operating lease agreement under IAS 17. According to IFRS 16, this lease receives the standard accounting treatment for operating leases existing at the date of initial application and the value of the right-of-use For the year ended December 31, 2020, we continued our investments in research and development equipment in both the United States of America and France. The addition in tangible assets reflects improvements of Calyxt and Cellectis sites for $5.2 million and other equipment for $2.9 million ($2.0 million of technical equipment and $0.9 million of other equipment). Assets under construction as of December 31, 2020 primarily relates to Cellectis’ new raw materials manufacturing facility in Paris ($2.3 million), a new commercial manufacturing facility in Raleigh, North Carolina ($37.9 million), and the balance relates to capital expenditure in New York office and in the Plants Segment. These amounts include $6.6 million related to internal costs capitalization.

Financial assets and liabilitie

Financial assets and liabilities	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Financial assets and liabilities	Note 8. Financial assets and liabilities 8.1 Accounting principles The new standard IFRS 9 “Financial instruments” is of mandatory application since January 1, 2018. Cellectis elected not to restate the 2016 and 2017 comparative periods, as authorized by the standard. Such adoption did not lead to any adjustment recorded in the Group opening equity at January 1, 2018. IFRS 9 comprises three phases: classification and measurement of financial assets and liabilities, impairment of financial assets and hedge accounting. Cellectis was not affected by the new classification required by the standard to determine the way financial assets are recognized and measured. Financial assets Under IFRS 9, Cellectis holds either: • financial assets measured at amortized cost or; • financial assets measured at fair value through profit or loss. Non-current Current financial assets correspond to investments and are recorded at fair value through profit and loss, which is the nominal value of the investment adjusted with the daily mark-to-market Trade and other receivables are recorded at fair value, which is the nominal value of invoices unless payment terms require a material adjustment for the time value discounting effect at market interest rates. Trade receivables are subsequently measured at amortized cost. A provision for expected credit losses for trade and other receivables is recognized if their recoverable amount is less than their carrying amount. The introduction of a new expected loss model for impairment of financial assets under IFRS 9 had no significant impact on the initial recognition of Cellectis trade and other receivables. Receivables are classified as current assets, except for those with a maturity exceeding 12 months after the reporting date. Government grants to Cellectis related to research and development expenses for research programs are recognized as subsidies receivables in the period in which the expenses subject to the subsidy have been incurred, provided there is a reasonable assurance that we will comply with conditions attached to the subsidy and that the subsidy will be received. Financial liabilities The application of IFRS 9 has no impact on the Cellectis’ accounting policy regarding financial liabilities. Financial liabilities include trade and other payables, finance leases, PPP loan, State Guaranteed loan « PGE » and conditional advances. We initially recognize financial liabilities on the transaction date, which is the date that we become a party to the contractual provisions of the instrument. We derecognize financial liabilities when our contractual obligations are discharged, canceled or expire. Financial liabilities are valued at amortized cost. The amount of interest recognized in financial expenses is calculated by applying the financial liability’s effective interest rate to its carrying amount. Any difference between the expense calculated using the effective interest rate and the actual interest payment impacts the value at which the financial liability is recognized. Liabilities for short term employee benefits are included in financial liabilities. They are recognized for the amount expected to be paid under short-term cash bonus or profit-sharing plans if we have a present legal or constructive obligation to pay the amount as a result of past service provided by the employee, and the obligation can be estimated reliably. 8.2 Detail of financial assets and liabilities The following table shows the carrying amounts and fair values of financial assets and financial liabilities. Accounting category Book value on the Fair Value 2019 Fair value through profit and loss Amortized cost $ in thousands Financial assets Non-current — 5,517 5,517 5,517 Trade receivables — 2,959 2,959 2,959 Subsidies receivables — 9,140 9,140 9,140 Current financial assets — 20,385 20,385 20,385 Cash and cash equivalents 340,522 — 340,522 340,522 Total financial assets 340,522 38,001 378,523 378,523 Financial liabilities Non-current — 46,540 46,540 46,540 Lease debts — 1,067 1,067 1,067 Trade payables — 29,264 29,264 29,264 Other current liabilities — 8,497 8,497 8,497 Total financial liabilities — 85,368 85,368 85,368 Accounting category Book value on the Fair Value 2020 Fair value through Amortized cost $ in thousands Financial assets Non-current — 7,007 7,007 7,007 Trade receivables — 5,171 5,171 5,171 Subsidies receivables — 10,703 10,703 10,703 Current financial assets — 27,091 27,091 27,091 Cash and cash equivalents 241,148 — 241,148 241,148 Total financial assets 241,148 49,972 291,120 291,120 Financial liabilities Non-current — 75,764 75,764 75,764 Other non-current — 28,836 28,836 28,836 Current lease debts — 6,696 6,696 6,696 Trade payables — 24,609 24,609 24,609 Other current liabilities — 19,127 19,127 19,127 Total financial liabilities — 155,032 155,032 155,032 8.3. Financial risks management We have exposure to the following risks arising from financial instruments: Foreign exchange risk A portion of our revenue is generated in currencies other than euro. Although our strategy is to favor the euro as our transaction currency when signing contracts, some agreements have been signed in US dollars (primarily agreements entered into by Calyxt and our agreement with Allogene Therapeutics, Inc.). As of December 31, 2019, 63% of our cash and cash equivalents were denominated in US dollars. As of December 31, 2020, 56% of our cash and cash equivalents were denominated in US dollars. Cellectis hedging policy is not affected by the application of IFRS 9. As of December 31, 2019 and 2020, we did not hold derivative financial instruments to hedge foreign currency exchange risks. Liquidity risk As of December 31, 2020, our financial debt consist million, a loan from a bank syndicate formed with HSBC, Société Générale, Banque Palatine and Bpifrance in the form of a state-guaranteed loan ( Pr ê t Garanti par l ’ Etat million (interests included), Calyxt’s paycheck protection program loan New-York We have incurred losses and cumulative negative cash flows from operations since our inception in 2000, and we anticipate that we will continue to incur losses for at least the next several years. As of December 31, 2020, we held $241.1 million in cash and cash equivalents. Interest rate risk We seek to engage in prudent management of our cash and cash equivalents, mainly cash on hand and common financial instruments (typically short- and mid-term Credit risk Credit risk is the risk of our financial loss if a customer or counterparty to a financial instrument defaults on its contract commitments. We are exposed to credit risk due to our trade receivables, subsidies receivables and cash equivalents. Our policy is to manage our risk by dealing with third parties with good credit standards.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Inventories	Note 9. Inventories Accounting policy Inventories are measured at the lower of cost and net realizable value. Cost is determined using the first in first out cost method. They include all costs of seed production and grain Calyxt purchases as well as costs to store, transport and process the grain into finished products. Consideration Calyxt receives from growers when they purchase seed is recorded as a reduction of inventory. Calyxt evaluates inventory balances for obsolescence on a regular basis using projected selling prices for our products, market prices for the underlying agricultural markets, the age of products and other factors that take into consideration our limited operating history. Prior to the commercialization of our high oleic soybean oil and high oleic soybean meal in early 2019, all Grain Costs were expensed as R&D. Description of inventories As of December 31, 2020, inventories amounted to $1.6 million, $1.4 million of which related to Calyxt’s grain and seed costs, and $0.2 million to raw materials and laboratory consumables (representing pharmaceutical and chemical products). As of December 31, 2019, inventories consisted of $2.9 million, $2.6 million of which related to Calyxt’s grain and seed costs, and $0.3 million to raw materials and laboratory consumables (representing pharmaceutical and chemical products). As of December 31, 2020, $3.9 million of net realizable value adjustments to period-end No provision for impairment has been recorded as of December 31, 2019.

Trade receivables and other cur

Trade receivables and other current assets	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Trade receivables and other current assets	Note 10. Trade receivables and other current assets Accounting policies for trade receivables and other current assets are described in Note 8.1. 10.1 Trade receivables As of December 31, As of December 31, 2019 2020 $ in thousands Trade receivables 3,513 5,787 Valuation allowance (554 ) (616 ) Total net value of trade receivables 2,959 5,171 All trade receivables have payment terms of less than one year. The trade receivables are mainly due to collaboration contracts and to the commercialization of Calyxt’s first products. 10.2 Subsidies receivables As of December 31, As of December 31, 2019 2020 $ in thousands Research tax credit 9,140 10,703 Total subsidies receivables 9,140 10,703 Research tax credit receivables as of December 31, 2020 include the accrual for a French research tax credit related to 2020 for $9.2 million and to previous periods for $1.3 million. The remaining amount relates to refundable tax credits in the United States. During December 2018, the French Tax Authority initiated an audit related to the 2014, 2015, 2016 and 2017 French research tax credits. Based on our current evaluation of the status of the audit, we do not believe that a provision should be recorded as of December 31, 2020. Research tax credit receivables as of December 31, 2019 mainly include the accrual for a French research tax credit related to 2019 for $7.9 million and to previous periods for $1.2 million. The remaining amount mainly relates to refundable tax credits in the United States. 10.3 Other current assets As of December 31, As of December 31, 2019 2020 $ in thousands VAT receivables 3,044 3,093 Prepaid expenses and other prepayments 11,829 14,113 Tax and social receivables 150 227 Deferred expenses and other current assets 594 12,210 Total other current assets 15,617 29,643 Prepaid expenses and other prepayments primarily include advances to our sub-contractors During the years ended December 31, 2020 and December 31, 2019, we prepaid certain manufacturing costs related to our product candidates UCART123, UCART22 and UCARTCS1 of which the delivery of products or services is expected in the coming months. As of December 31, 2019, deferred expenses and other current assets mainly relates to commission fees with respect to a letter of credit relating to our Raleigh facility, a Calyxt broker receivable and certain down payments to suppliers. As of December 31, 2020, deferred expenses and other current assets mainly relates to a $6.2 million receivable following Cellectis’ employees option exercise, a Calyxt broker receivable and certain down payments to suppliers for $2.7 million, as well as a right of $3.0 million to obtain equipment at our Raleigh facility which generates an equivalent financial liability. As of December 31, 2019, tax and social receivables relate mainly to social charges on personnel expenses and tax reimbursement. As of December 31, 2020, tax and social receivables relate mainly to social charges on personnel expenses.

Current financial assets and Ca

Current financial assets and Cash and cash equivalents	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Current financial assets and Cash and cash equivalents	Note 11. Current financial assets and Cash and cash equivalents As of December 31, 2019 Carrying amount Unrealized Gains/(Losses) Estimated fair value $ in thousands Current financial assets 20,385 — 20,385 Cash and cash equivalents 340,522 — 340,522 Current financial assets and cash and cash equivalents 360,907 — 360,907 As of December 31, 2020 Carrying amount Unrealized Gains/(Losses) Estimated fair value $ in thousands Current financial assets 27,091 — 27,091 Cash and cash equivalents 241,148 — 241,148 Current financial assets and cash and cash equivalents 268,239 — 268,239 11.1 Current financial assets Accounting policies Current financial assets include current restricted cash for $15.4 million and other current financial assets for $11.7 million related to a Calyxt’s short-term investment. As of December 31, 2020, restricted cash consists of: i. deposit to secure commitment to supplier regarding the manufacturing facility construction for $15 million classified as short-term restricted cash included within current financial assets, and ii. deposits to secure a Calyxt furniture and equipment sale-leaseback for $1.0 million of which $0.4 million are classified as short-term restricted cash included within current financial assets. As of December 31, 2019, restricted cash consists of deposit to secure commitment to supplier regarding the manufacturing facility construction for $20 million classified as short-term restricted cash included within current financial assets and deposits to secure a Calyxt furniture and equipment sale-leaseback for $1.4 million of which $0.4 million are classified as short-term restricted cash included within current financial assets. Financial assets are measured at fair value through profit or loss in accordance with IAS 39 include the following: • Financial assets including embedded derivatives for which Cellectis elected to designate at fair value through profit or loss; • Financial assets managed on a fair value basis; and • Derivative instruments that are not documented in hedging relationships. IFRS 13 (Fair Value Measurement) requires counterparty and own credit risk to be taken into account when measuring the fair value of financial instruments. This risk is estimated on the basis of observable, publicly-available statistical data. 11.2 Cash and cash equivalents Accounting policy Cash and cash equivalents are held for the purpose of meeting short-term cash commitments rather than for the purpose of investment or for other purposes. They are readily convertible into a known amount of cash and are subject to an insignificant risk of changes in value. Cash and cash equivalents include cash, bank accounts, money market funds and fixed bank deposits that meet the definition of a cash equivalent. Cash equivalents are fair valued at the end of each reporting period. Details of cash and cash equivalents As of December 31, As of December 31, 2019 2020 $ in thousands Cash and bank accounts 270,630 164,586 Money market funds 13,722 13,977 Fixed bank deposits 56,170 62,585 Total cash and cash equivalents 340,522 241,148 Money market funds earn interest and are refundable overnight. Fixed bank deposits have fixed original terms that are less than three months or are readily convertible to a known amount of cash.

Financial liabilities

Financial liabilities	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Financial liabilities	Note 12. Financial liabilities 12.1 Detail of financial liabilities As of December 31, As of December 31, 2019 2020 $ in thousands Lease debts 46,540 75,764 State Guaranteed loan « PGE » — 22,701 PPP loan 1,518 Other non-current — 4,617 Total non-current 46,540 104,600 Lease debts 1,067 6,696 Total current financial liabilities 1,067 6,696 Trade payables 29,264 24,609 Other current liabilities 8,497 19,127 Total Financial liabilities 85,368 155,032 As of December 31, 2020, the increase in non-current • a financial liability of $3.0 million related to an equipment rental agreement at our Raleigh good manufacturing practices (“GMP”) facility, which will be reclassified to lease debt when the equipment is delivered or accepted by Cellectis; • Cellectis’ obtention of a $1.5 million loan to finance leasehold improvement at our location in New-York; • Cellectis Biologics Inc’s obtention of $3.3 million tenant improvement allowance at our location in Raleigh; • Calyxt’s obtention of a $1.5 million paycheck protection program loan under the U.S. Coronavirus Aid, Relief and Economic Security (CARES) Act, for which Calyxt has applied for forgiveness on October 21, 2020 but which has not been granted yet as of December 31, 2020; and • Cellectis’s obtention of an € 18.5 million (or $22.7 COVID-19 to 12.2 Due dates of the financial liabilities Balance as of December 31, 2020 Book Value Less than One One to Five More than Five $ in thousands Lease debts 82,460 6,696 30,706 45,058 Other financial liabilities 28,836 78 24,698 4,061 Financial liabilities 111,296 6,774 55,404 49,118 Trade payables 24,609 24,609 — — Other current liabilities 19,127 19,127 — — Total financial liabilities 155,032 50,510 54,404 49,118

Other current liabilities

Other current liabilities	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Other current liabilities	Note 13. Other current liabilities As of December 31, As of December 31, 2019 2020 $ in thousands VAT Payables 130 81 Accruals for personnel related expenses 7,295 13,235 Other 1,072 6,077 Total 8,497 19,393 Accruals for personnel are related to annual bonuses, vacations accruals and social expenses on stock options. The increase in accruals for personnel related expenses between December 31, 2019 and December 31, 2020, is mainly driven by higher accrual for paid vacations, French social security and annual bonuses due to the increase of headcount recruited both in the United States and in France. As of December 31, 2020 “Other” mainly include payables to fixed asset suppliers for $3.7 million, Board of Directors attendance fees for $0.3 million liabilities and other tax liabilities for $0.2 million. As of December 31, 2019 “Other” mainly include payables to fixed asset suppliers for $0.6 million, Board of Directors attendance fees for $0.3 million liabilities and other tax liabilities for $0.2 million.

Deferred revenues and contract

Deferred revenues and contract liabilities	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Deferred revenues and contract liabilities	Note 14. Deferred revenues and contract liabilities Accounting policies Details of deferred revenues and deferred income As of December 31, 2019 As of December 31, 2020 $ in thousands Deferred revenues and contract liabilities 20,033 452 Others — — Total Deferred revenue and contract liabilities 20,033 452 Deferred revenues The deferred revenues and contract liabilities as of December 31, 2019 were mainly attributable to upfront payments and milestone payments for the collaboration agreements with Servier. During the period ended December 31, 2020, we recognized as revenue $16.9 million related to upfront payments and $2.5 million related to milestone payments on released targets based on the amendment signed in March 2020 to our collaboration agreement with Servier.

Capital

Capital	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Capital	Note 15. Capital 15.1 Share capital issued Accounting policy In general, each shareholder is entitled to one vote per share at any general shareholders’ meeting. However, our By-Laws Nature of the Transactions Share Capital Share premium Number of shares Nominal value $ in thousands in $ Balance as of January 1, 2018 2,367 614,037 35,960,062 0.05 Capital Increase 379 178,230 6,146,000 — Exercise of share warrants, employee warrants and stock options 19 7,751 324,007 — Non-cash — 28,507 — — Balance as of December 31, 2018 2,765 828,525 42,430,069 0.05 Capital Increase 2 — 35,600 — Exercise of share warrants, employee warrants and stock options — — — — Non-cash — 14,951 — — Other movements — 2 — Balance as of December 31, 2019 2,767 843,478 42,465,669 0.05 Exercise of share warrants, employee warrants and stock options 18 6,101 314,517 — Non-cash — 14,365 — — Other movements — (32 ) — Balance as of December 31, 2020 2,785 863,912 42,780,186 0.05 Capital evolution in 2020 • During the full year ended December 31, 2020, 20,464 ordinary shares were issued upon the exercise of 19,702 employee warrants (“bons de souscription de parts de créateurs”) for t o Capital evolution in 2019 • During the full year ended December 31, 2019, 35,600 free shares were converted to 35,600 ordinary shares. Capital evolution in 2018 • During the full year ended December 31, 2018, 6,146,000 ordinary shares were issued upon the closing of a follow-on non-employees BSA 2011: On October 28, 2011, using the delegation of authority granted by the General Assembly held the same day, we issued 12,195,113 warrants (Bon de Souscription d’Actions or “BSA”) to the existing shareholders with a ratio of one BSA for one share. October 28, 2014 was the closing date for the exercise of the “BSA 2011.” Pursuant to the terms of the plan, we issued 1,470,836 ordinary shares for gross proceeds of $16.4 million. Voting rights: After a shareholder continuously holds ordinary shares for two years, each ordinary share held by such shareholder is entitled to two votes. • At December 31, 2020, we had 42,780,186 ordinary shares outstanding of which 6,067,389 had a double voting right. • At December 31, 2019, we had 42,465,669 ordinary shares outstanding of which 4,389,581 had a double voting right. • At December 31, 2018, we had 42,430,069 ordinary shares outstanding of which 5,016,911 had a double voting right. Otherwise, our ordinary shares are not entitled to any preferential voting right or restriction. 15.2 Share warrants and non-employee Share warrants and non-employee Date Type Number of Number of Number of Number of Number of Maximum of shares Number of Strike price per 07/27/2010 BSPCE 19,702 — 19,702 — — — — 7.97 03/24/2015 Stock Options 1,612,994 — — 21,391 1,591,603 1,591,603 1,591,603 38.45 03/27/2015 BSA 130,000 — — — 130,000 130,000 130,000 38.45 05/18/2015 BSA 50,000 — — — 50,000 50,000 50,000 29.58 09/08/2015 BSA 224,200 — — — 224,200 224,200 224,200 28.01 09/08/2015 Stock Options 1,623,200 — — 24,500 1,598,700 1,598,700 1,598,700 27.55 03/14/2016 BSA 147,025 — — 147,025 147,025 147,025 27.37 03/14/2016 Stock Options 1,652,595 — 2,354 13,536 1,636,705 1,636,705 1,636,705 22.44 10/28/2016 BSA 148,000 — — 148,000 148,000 148,000 18.68 10/28/2016 Stock Options 2,178,893 238,660 21,599 1,918,634 1,918,634 1,918,634 17.90 10/11/2017 BSA 200,000 — — — 200,000 200,000 200,000 24.34 10/11/2017 Stock Options 960,000 — 1,000 35,000 924,000 924,000 707,722 22.57 10/08/2018 Free shares 3,000 — 3,000 — — — — 23.84 10/08/2018 Stock Options 50,000 — — 30,000 20,000 20,000 9,996 24.80 12/17/2018 Free shares 13,000 — — 13,000 — — — 16.00 12/17/2018 Stock Options 40,000 — — 40,000 — — — 18.37 03/07/2019 Free shares 2,500 — — — 2,500 2,500 — 16.00 04/24/2019 Stock Options 1,469,700 — 41,539 162,646 1,265,515 1,265,515 531,538 18.25 04/24/2019 Free shares 6,500 — — — 6,500 6,500 — 18.01 07/16/2019 Free shares 4,000 — — — 4,000 4,000 — 14.01 11/06/2019 Stock Options 55,000 — — 25,000 30,000 30,000 7,500 11.06 11/06/2019 Free shares 21,500 — — 6,500 15,000 15,000 — 11.32 11/18/2019 Stock Options 30,000 — 7,500 — 22,500 22,500 — 12.33 11/18/2019 Free shares 16,500 — — — 16,500 16,500 — 12.16 03/04/2020 Free shares — 6,500 — — 6,500 6,500 — 14.54 04/14/2020 Free shares — 20,000 — — 20,000 20,000 — 9.14 04/14/2020 Stock Options — 160,000 — — 160,000 160,000 — 8.27 06/19/2020 Free shares — 16,500 — — 16,500 16,500 — 14.76 06/19/2020 Stock Options — 17,000 — — 17,000 17,000 — 15.84 07/20/2020 Free shares — 10,000 — — 10,000 10,000 — 15.76 07/20/2020 Stock Options — 17,000 — — 17,000 17,000 — 15.12 08/05/2020 Free shares — 70,000 — — 70,000 70,000 — 14.00 08/05/2020 Stock Options — 212,000 — — 212,000 212,000 — 14.62 09/11/2020 Free shares — 15,000 — — 15,000 15,000 — 14.58 09/11/2020 Free shares — 6,500 — — 6,500 6,500 — 14.98 09/11/2020 Stock Options — 45,000 — — 45,000 45,000 — 14.36 10/14/2020 Free shares — 423,285 — 6,535 416,750 416,750 — 22.45 11/05/2020 Stock Options — 28,000 — — 28,000 28,000 — 14.62 11/05/2020 Free shares — 16,600 — — 16,600 16,600 — 14.76 12/16/2020 Free shares — 7,300 — — 7,300 7,300 — 23.75 Total 10,658,309 1,070,685 313,755 399,707 11,015,532 11,015,532 8,901,623 Holders of vested stock options and warrants are entitled to subscribe to a capital increase of Cellectis at predetermined exercise price. • In 2020, our subsidiary Calyxt granted stock options, restricted stock unit and performance stock unit in Calyxt representing as of December 31, 2020 a 2.7% interest of that subsidiary if fully exercised to a group of its employees, directors, executive officers and consultants. The compensation expense for 2020 amounted to $6.7 million (see Note 16). • In 2019, our subsidiary Calyxt granted stock options, restricted stock unit and performance stock unit in Calyxt representing as of December 31, 2019 a 6.1% interest of that subsidiary if fully exercised to a group of its employees, directors, executive officers and consultants. The compensation expense for 2019 amounted to $4.4 million (see Note 16). • In 2018, our subsidiary Calyxt granted stock options and restricted stock unit in Calyxt representing as of December 31, 2018 a 3.1% interest of that subsidiary if full y 15.3 Non-controlling On July 25, 2017, Calyxt closed its IPO with $64.4 million in gross proceeds to Calyxt from the sale of 8,050,000 shares at $8 per share, including the full exercise of the underwriter’s over-allotment option and Cellectis’ purchase of $20.0 million of shares in the IPO. On May 22, 2018, Calyxt completed a follow-on follow-on SEC-registered, As of December 31, 2020, non-controlling The following table summarizes the information relating to each of our subsidiaries that reported non-controlling CALYXT 2019 2020 $ in thousands Revenue 7,294 22,892 Net Profit (Loss) (40,142 ) (43,902 ) Net Profit (Loss) attributable to NCI (13,121 ) (16,409 ) Other comprehensive income (1,237 ) (1,196 ) Total comprehensive income (41,378 ) (45,098 ) Total comprehensive income attributable to NCI (12,856 ) (15,942 ) Current assets 63,528 39,590 Non-current 22,518 23,737 Current liabilities 6,642 6,945 Non-current 15,121 19,507 Net assets 64,283 36,875 Net assets attributable to NCI 19,973 13,035

Share-based payments

Share-based payments	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Share-based payments	Note 16. Share-based payments 16.1 Detail of Cellectis equity awards Holders of vested Cellectis stock options and warrants are entitled to exercise such options and warrants to purchase Cellectis Ordinary shares at a fixed exercise price established at the time of such options and warrants are granted during their useful life. For stock options and warrants, we estimate the fair value of each option on the grant date or other measurement date if applicable using a Black-Scholes option-pricing model, which requires us to make predictive assumptions regarding future stock price volatility, employee exercise behavior, dividend yield, and the forfeiture rate. We estimate our future stock price volatility based on Cellectis historical closing share prices over the expected term period. Our expected term represents the period of time that options granted are expected to be outstanding determined using the simplified method. The risk-free interest rate for periods during the expected term of the options is based on the French government securities with maturities similar to the expected term of the options in effect at the time of grant. We have never declared or paid any cash dividends and do not presently plan to pay cash dividends in the foreseeable future. Consequently, we used an expected dividend yield of zero. Options may be priced at 100 percent or more of the fair market value on the date of grant, and generally vest over four years after the date of grant. Options generally expire within ten years after the date of grant. Stock Options The weighted-average fair values of stock options granted and the assumptions used for the Black-Scholes option pricing model were as follows: 2018 2019 2020 Weighted-Average fair values of stock options granted 8.84€ 10.19€ 7.40€ Assumptions: Risk-free interest rate 0.13% - 0.21% -0.38% - 0.09% 0.00% Share entitlement per options 1 1 1 Exercise price 18.37€ - 24.80€ 11.06€ - 18.25€ 8.27€ - 15.84€ Grant date share fair value 16€ - 17.78€ 11.32€ - 17.80€ 9.14€ - 15.76€ Expected volatility 63.3% - 63.4% 63.8% - 66.6% 61.3% - 62.8% Expected term (in years) 6.25 6.15 - 6.25 6.15 Vesting conditions Service Service Service Vesting period Graded Graded Graded Information on stock option activity follows: Options Weighted- Options Weighted- Remaining Balance as of December 31, 2018 5,644,044 27.47 € 8,978,106 25.36 € 7.3y Granted — — € 1,650,800 17.90 € Exercised — — € 0 0.00 € Forfeited or Expired — — € (956,524 ) 24.01 € Balance as of December 31, 2019 6,922,172 26.30 € 9,672,382 24.22 € 6.8y Granted — — € 479,000 12.54 € Exercised — — € (291,053 ) 17.86 € Forfeited or Expired — — € (373,672 ) 20.61 € Balance as of December 31, 2020 8,002,398 25.28 € 9,486,657 23.97 € 5.9y Share-based compensation expense related to stock option awards was $8.9 million in 2020, $13.4 million in 2019, and $26.0 million in 2018. Warrants The weighted-average fair values of warrants granted and the assumptions used for the Black-Scholes option pricing model were as follows: 2016 2017 Weighted-Average fair values of warrants granted 9.33€ 13.20€ Assumptions: Risk-free interest rate 0.00% - 0.12% Share entitlement per options 1 1 Exercise price 18.68€ - 27.37€ 24.34€ Grant date share fair value 16.42€ - 22.48€ 24.95€ Expected volatility 62.8% - 63.1% 64.7% Expected term (in years) 6 6 Vesting conditions Service Service Vesting period Graded Graded Information on warrants activity follows: Warrants Weighted- Warrants Weighted- Remaining Balance as of December 31, 2018 687,252 27.74 € 918,927 26.74 € 7.2y Granted — — — — Exercised — — — — Forfeited or Expired — — — — Balance as of December 31, 2019 852,260 35.35 € 918,927 35.12 € 6.9y Granted — — — — Exercised — — (19,702 ) 8.28 € Forfeited or Expired — — — — Balance as of December 31, 2020 899,225 27.15 € 899,225 27.15 € 5.3y Share-based compensation expense related to warrants awards was $0.3 million in 2020, $0.9 million in 2019, and $2.3 million in 2018. Free shares The free shares granted prior to 2018 are subject to a two-year one-year two-years Information on free shares activity follows: Number of Free Weighted- Unvested balance at December 31, 2018 71,600 27.37 € Granted 57,000 13.04 € Vested (35,600 ) 25.74 € Cancelled (26,000 ) 21.65 € Unvested balance at December 31, 2019 67,000 13.98 € Granted (1) 591,685 20.10 € Vested (3,000 ) 23.84 € Cancelled (26,035 ) 16.45 € Unvested balance at December 31, 2020 629,650 19.59 € (1) 423,285 free shares have been granted in October 2020 under the 2018 Stock Option Plan and are under non-market performance vesting condition s t hese shares were voided as of December 31, 2020. The fair value of free shares corresponds to the grant date share fair value. We have never declared or paid any cash dividends and do not presently plan to pay cash dividends in the foreseeable future. Consequently, we used an expected dividend yield of zero Share-based compensation expense related to free shares awards was $0.9 million in 2020, $0.7 million in 2019, and $0.2 million in 2018. 16.2 Detail of Calyxt equity awards Stock Options The estimated fair values of stock options granted and the assumptions used for the Black-Scholes option pricing model were as follows: 2018 2019 2020 Weighted-Average fair values of stock options granted $9.09 $10.18 $3.24 Assumptions: Risk-free interest rate 2.2% - 3% 1.7% - 2.5% 0.3% - 1.7% Share entitlement per options 1 1 1 Exercise price $14.24 - $23.39 $4.05 - $15.39 $3.22 - $7.30 Grant date share fair value $14.24 - $23.39 $4.05 - $15.39 $3.22 - $7.30 Expected volatility 40.9% - 57.2% 52.6% - 78.9% 77.4% - 81.2% Expected term (in years) 5.6 - 10.0 6.8 -10.0 6.0 - 10.0 Vesting conditions Service Service Service Vesting period Graded Graded Graded Calyxt estimates the fair value of each option on the grant date or other measurement date if applicable using a Black-Scholes option-pricing model, which requires Calyxt to make predictive assumptions regarding future stock price volatility, employee exercise behavior, dividend yield, and the forfeiture rate. Calyxt estimates its future stock price volatility using the historical volatility of comparable public companies over the expected term of the option. Calyxt’s expected term represents the period of time that options granted are expected to be outstanding determined using the simplified method. The risk-free interest rate for periods during the expected term of the options is based on the U.S. Treasury zero-coupon Calyxt has not paid and does not expect to pay dividends for the foreseeable future. Options may be priced at 100 percent or more of the fair market value on the date of grant, and generally vest over six ten Information on stock option activity follows: Options Weighted- Options Weighted- Remaining Balance as of December 31, 2018 1,278,038 $ 7.45 3,201,887 $ 10.67 8.2y Granted — — 1,590,000 $ 13.80 Exercised — — (95,327 ) $ 3.61 Forfeited or Expired — — (227,696 ) $ 14.68 Other activity 12,495 $ 13.29 Balance as of December 31, 2019 1,789,567 $ 8.73 4,481,359 $ 11.73 6.8y Granted — — 887,765 $ 4.67 Exercised — — (58,575 ) $ 3.60 Forfeited or Expired — — (689,376 ) $ 12.89 Balance as of December 31, 2020 2,347,665 $ 10.15 4,621,173 $ 10.30 6.2y Stock-based compensation expense related to stock option awards was $4.0 million in 2020, $6.8 million in 2019 and $3.2 million in 2018. The options granted under the plans were originally only exercisable upon a triggering event or initial public offering as defined by the plans. Restricted Stock Units Units settled in stock subject to a restricted period may be granted to key employees under the 2017 Omnibus Plan. Restricted stock units generally vest and become unrestricted over five years after the date of grant. Information on restricted stock unit activity follows: Number of Weighted-Average Unvested balance at December 31, 2018 1,051,414 $ 14.11 Granted 100,000 $ 12.48 Vested (324,043 ) $ 9.69 Cancelled (13,845 ) $ 12.72 Unvested balance at December 31, 2019 813,526 $ 10.31 Granted 105,633 $ 6.54 Vested (309,693 ) $ 10.08 Cancelled (61,659 ) $ 10.80 Unvested balance at December 31, 2020 547,807 $ 9.49 The fair value of restricted stock units corresponds to the grant date share fair value. Calyxt has not paid and does not expect to pay dividends for the foreseeable future. Share-based compensation expense related to restricted stock units awards was $2.3 million in 2020, $4.9 million in 2019 and $5.5 million in 2018. Performance Stock Unit In June 2019, Calyxt granted performance stock units, which carry a market condition based on Calyxt share price. These awards contain a continuous service period of three years, the performance period, from the date of grant, followed by a restricted period of two years if the shares are issued following the performance period during which the grantee is required to provide continuous service and the awarded shares must be held by the grantee until the end of the period. The number of shares of common stock delivered following the performance period depends upon the change in Calyxt share price during the performance period. Calyxt granted a targeted 311,667 performance stock units, the performance criteria allow for the actual payout to be between zero and 120 percent of target. The fair value of the performance stock units and the assumptions used for the Monte Carlo simulation were as follows: Date of grant 06/28/2019 Estimated fair values of performance stock units granted $ 7.06 Assumptions: Risk-free interest rate 1.71 % Expected volatility 75.0 % Expected term (in years) 3.0 years Information on performance stock unit activity follows: Number of Weighted- Unvested balance at December 31, 2019 311,667 $ 7.06 Granted — — Vested — — Cancelled — — Unvested balance at December 31, 2020 311,667 $ 7.06 Share-based compensation expense related to performance stock unit awards was $0.4 million in 2020 and $0.2 million in 2019.

Earnings per share

Earnings per share	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Earnings per share	Note 17. Earnings per share Accounting policy Basic earnings per share are calculated by dividing profit attributable to our ordinary shareholders by the weighted average number of ordinary shares outstanding during the period, adjusted to take into account the impact of treasury shares. Diluted earnings per share is calculated by adjusting profit attributable to ordinary shareholders and the weighted average number of ordinary shares outstanding, for the effects of all potentially dilutive ordinary shares (stock-options, free shares, share warrants, employee warrants). Detail of earnings per share For the year ended December 31, 2018 2019 2020 Net income (loss) attributable to shareholders of Cellectis ($ in thousands) (78,693 ) (102,091 ) (81,074 ) Adjusted weighted average number of outstanding shares, used to calculate both basic and diluted net result per share 40,774,197 42,442,136 42,503,447 Basic / Diluted net income (loss) per share attributable to shareholders of Cellectis Basic net income (loss) attributable to shareholders of Cellectis per share ( $ /share) (1.93 ) (2.41 ) (1.91 ) Diluted net income (loss) attributable to shareholders of Cellectis per share ( $ /share) (1.93 ) (2.41 ) (1.91 )

Provisions

Provisions	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Provisions	Note 18. Provisions Accounting policy A provision is recognized if, as a result of a past event, we have a present legal or constructive obligation that can be estimated reliably, and it is probable that an outflow of economic benefits will be required to settle the obligation. The amount recognized as a provision is the best estimate of the expenditure required to settle the present obligation at the reporting date. Provisions for retirement and other benefits Our defined benefit obligations, and their cost, are determined using the projected unit credit method. The method consists in measuring the obligation based on a projected end-of-career Actuarial assumptions used to determine the benefit obligations are specific to each country and each benefit plan. The discount rate used is the yield at the reporting date on AA credit-rated bonds with maturity dates that approximate the expected payments for our obligations. Actuarial gains or losses are recognized in the statement of comprehensive loss for the year in which they occur. Other long-term employee benefits Our net obligation for long-term employee benefits other than retirement plans is equal to the value of employees’ future benefits vested in exchange for services rendered in the current and prior periods. The benefits are discounted and the fair value of any plan assets is deducted. The obligation is measured using the projected unit credit method. The discount rate is the same as the one used for the provisions for retirement and other benefits. Actuarial gains or losses are recognized in profit or loss for the year in which they occur. Termination benefits Termination benefits are recognized as a liability and expense at the earlier of the following dates: • When the entity can no longer withdraw the offer of those benefits; and • When the entity recognizes costs for a restructuring that is within the scope of IAS 37 Provisions and involves the payment of termination benefits. Details of provisions 01/01/2019 as restated Reclassification Additions Amounts used Reversals OCI 12/31/2019 $ in thousands Pension 2,278 — 314 — — 263 2,855 Loss on contract — 1,043 690 (1,461 ) — — 272 Employee litigation 41 — 715 (43 ) (75 ) 1 639 Commercial litigation 850 — 2,604 (595 ) (17 ) (11 ) 2,832 Total 3,169 1,043 4,323 (2,099 ) (92 ) 253 6,598 Non-current 2,278 314 — — 263 2,855 Current provisions 891 1,043 4,009 (2,099 ) (92 ) (10 ) 3,743 01/01/2020 Additions Amounts used Reversals OCI 12/31/2020 Pension 2,855 410 — — 745 4,010 Loss on contract 272 — (272 ) — — — Employee litigation 639 229 (308 ) (49 ) 49 560 Commercial litigation 2,832 329 (1,692 ) (985 ) 86 571 Total 6,598 968 (2,272 ) (1,034 ) 881 5,141 Non-current 2,855 410 — — 745 4,010 Current provisions 3,743 558 (2,272 ) (1,034 ) 136 1,131 * As of January 1, 2019, Montvale, New Jersey facility lease agreement provision for loss on contract was scoped under IFRS 16 and classified as lease debts. During the period, the agreement has been discontinued which changed its treatment placing it outside the scope of IFRS 16 and resulting in the reclassification to “loss on contract” presented above. During the year ended December 31, 2020, additions mainly relate to (i) commercial litigation for $0.3 million, (ii) employee litigation for $0.2 million and (ii) pension service cost of the period for $0.4 million. The amounts used and reversed during the period mainly relate to (i) fee payments in connection with the Montvale, New Jersey facility discontinuation, for $0.3 million, (ii) the settlement of employee litigation for $0.3 million and (iii) the settlement of a commercial litigation (for $2.7 million, of which $1.7 million was paid). During the year ended December 31, 2019, additions mainly relate to (i) the discontinuation of the lease for a non-operational Commitments for compensation payable to employees upon their retirement France In France, pension funds are generally financed by employer and employee contributions and are accounted for as defined contribution plans, with the employer contributions recognized as expense as incurred. There are no actuarial liabilities in connection with these plans. Expenses recorded in the years ended December 31, 2018, 2019 and 2020 amounted to $1.5 million, $1.1 million and $1.5 million, respectively. French law also requires payment of a lump sum retirement indemnity to employees based on years of service and annual compensation at retirement. Benefits do not vest prior to retirement. We are paying this defined benefit plan. It is calculated as the present value of estimated future benefits to be paid, applying the projected unit credit method whereby each period of service is seen as giving rise to an additional unit of benefit entitlement, each unit being measured separately to build up the final. The calculation of legal compensation for termination has changed in 2017 following the publication of a new French law. The two important changes are: • Seniority conditions: the employee must be entitled to an indemnity of 8 working months against one year before. • Calculation of the allowance: 1/4 of a month of salary per year of seniority up to 10 years, against 1/5 before, and no change beyond the 11th year. As part of the estimation of the retirement indemnity to employee, the following assumptions were used for all categories of employees: 2018 2019 2020 % social security contributions 45.00% 45.00% 45.00% Salary increases 3.50% 3.50% 3.50% Discount rate 1.75% 1.00% 0.68% Terms of retirement voluntary retirement Retirement age 65 years old 65 years old 65 years old The discount rates are based on the market yield at the end of the reporting period on high quality corporate bonds. The following table shows reconciliation from the opening balances to the closing balances for net defined benefit liability and its components. $ in thousands As of January 1, 2018 (2,194 ) Current service cost (276 ) Interest cost (38 ) Benefit paid 54 Actuarial gains and losses 70 Reclassification/CTA 105 As of December 31, 2018 (2,278 ) Current service cost (275 ) Interest cost (39 ) Benefit paid Actuarial gains and losses (303 ) Reclassification/CTA 40 As of December 31, 2019 (2,855 ) Current service cost (381 ) Interest cost (29 ) Benefit paid Actuarial gains and losses (411 ) Reclassification/CTA (334 ) As of December 31, 2020 (4,010 ) United States of America There is no defined benefit plan for Cellectis S.A.’s subsidiaries located in the United States.

Commitments

Commitments	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Commitments	Note 19. Commitments Accounting policy The commitment amounts are associated with contracts that are enforceable and legally binding and that specify all significant terms, including fixed or minimum services to be used, fixed, minimum or variable price provisions, and the approximate timing of the actions under the contracts. Thy do not include obligations under agreements that we can cancel without a significant penalty. Details of commitments As of December 31, 2020 Total Less than 1 1 - 3 3 - 5 More than 5 $ in thousands License agreements 19,110 1,530 3,060 3,060 11,460 Manufacturing agreements 942 942 — — — Clinical & R&D agreements 1,353 946 408 — — Construction agreements 9,272 9,272 — — — Other agreements 21,704 21,631 72 — — Total commitments 52,381 34,321 3,540 3,060 11,460 Obligations under the terms of lease agreement Almost all of our lease agreement are accounted for under IFRS 16 and thereby are presented in the statement of consolidated financial position. The commitments related to operating leases exempted from IFRS 16 application are immaterial. Obligations under the terms of license agreements We have entered into various license agreements with third parties that subject us to certain fixed license fees, as well as fees based on future events, such as research and sales milestones. We also have collaboration agreements whereby we are obligated to pay royalties and milestones based on future events that are uncertain and therefore they are not included in the table above. Obligations under the terms of manufacturing agreements We have manufacturing agreements whereby we are obligated to pay for services rendered in the next year regarding our products UCART123, UCARTCS1 and UCART22. Obligations under the terms of Clinical & Research agreements We have entered into clinical and research agreements where we are obligated to pay for services to be provided in the next years regarding our research collaboration agreements, clinical trials and translational research projects. Obligations under the terms of Construction agreements We have entered into a construction agreement regarding our manufacturing facility based in Raleigh, North Carolina, where we committed to pay for construction work. Obligations under the terms of other agreements Calyxt enters into seed and grain production agreements (Forward Purchase Contracts) with seed producers and growers. Calyxt announced in December 2020 that Archer Daniels Midland has committed to purchase over four million bushels of Calyxt’s grain, which includes all the 2020 soybean crop, which Calyxt will purchase from growers between January 1, 2021 and August 31, 2021. Calyxt expects to sell that grain throughout 2021 and no later than December 31, 2021. Calyxt expects to sell the remaining grain to Archer Daniels Midland at market prices, and as a result, Calyxt will continue to hedge fixed price grain inventories and fixed price Forward Purchase Contracts to mitigate the risk changing market prices may have on Calyxt’s margins. The seed contracts often require Calyxt to pay prices for the seed produced at an exchange-traded price of grain plus a premium with the seed grower having the option to fix their price with Calyxt throughout the term of the agreement. The grower contracts are linked to a commodity futures market prices with the grain grower having the option to fix their price with Calyxt throughout the term of the agreement. The grain grower contracts allow for delivery of grain to Calyxt at harvest if so specified when the agreement is executed, otherwise delivery occurs on a date that Calyxt elects through August 31 of the following year. In all periods presented, we considered Forward Purchase Contracts as normal purchases and not derivatives. Any mark-to-market

Related parties

Related parties	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Related parties	Note 20. Related parties Key management personnel remuneration Key management personnel include members of the Board of Directors and the CODM as of December 31, 2020, as described in Note 3.5. Short-term employee benefits paid to key management personnel totaled to $4.4 million in the fiscal year 2018, $5.2 million in the fiscal year 2019 and $6.3 million in the fiscal year 2020. On September 4, 2014, the Board of Directors adopted a change of control plan which applies to the members of the CODM. This plan defines the conditions under which a severance package will be paid after a change of control of our company. Key management personnel employment agreements include a termination indemnity or additional post-employment compensation. Key management personnel received an aggregate of 380,100 securities in share-based remuneration (free shares and stock options) over the year ended December 31, 2020. The associated non-cash Other transactions with related parties Mr. Godard, a member of the Board of Directors, entered into two service agreements with us and provided consultancy services in the area of (i) global development strategy and (ii) specific development of agricultural biotechnology activities. Compensation paid for those services in the years ended December 31, 2018, 2019 and 2020 amounted to $70 thousand, $71 thousand and $58 thousand respectively. No balances were outstanding at the end of each fiscal year. As of December 31, 2020, Mr. Godard held 220,175 non-employee

Subsequent events

Subsequent events	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Subsequent events	Note 21. Subsequent events On February 16, 2021, Cytovia Therapeutics, Inc., a biopharmaceutical company developing allogeneic “off-the-shelf” (CAR)-NK ® CAR-NK ® On February 19, 2021 Yves Ribeill, Ph.D., Chair of the Board of Directors of Calyxt, Inc., was appointed as the Executive Chair of the Board of Directors and in that capacity, will serve as Calyxt’s principal executive officer until the appointment of a successor to James Blome, Calyxt’s former Chief Executive Officer. Mr. Blome is entitled to compensation and benefits as part of this termination without cause, and in the first quarter of 2021 Calyxt expect to record up to $2.3 million of cash expense for separation-related payments as well as an additional non-cash sign-on s non-cash

Accounting principles (Policies

Accounting principles (Policies)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Basis for preparation	2.1 Basis for preparation The Consolidated Financial Statements of Cellectis as of and for the year ended December 31, 2020 were approved by our Board of Directors on March 4, 2021. Our Consolidated Financial Statements are presented in U.S. dollars. See Note 2.3. The Consolidated Financial Statements have been prepared in accordance with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”) and in conformity with IFRS as endorsed by the European Union. The Consolidated Financial Statements have been prepared using the historical cost measurement basis except for certain assets and liabilities that are measured at fair value in accordance with IFRS. IFRS include International Financial Reporting Standards (“IFRS”), International Accounting Standards (“the IAS”), as well as the interpretations issued by the Standards Interpretation Committee (“the SIC”), and the International Financial Reporting Interpretations Committee (“IFRIC”). The significant accounting methods used to prepare the Consolidated Financial Statements are described below. Application of new or amended standards or new amendments The following pronouncements and related amendments have been adopted by us from January 1, 2020 but had no significant impact on the Consolidated Financial Statements: • Amendments to References to the Conceptual Framework in IFRS Standards (Effective for the accounting periods as of January 1, 2020) • Amendment to IFRS 3 “Business Combinations” (Effective for the accounting periods as of January 1, 2020) • Amendments to IAS 1 “Presentation of financial statements” and IAS 8 “Accounting policies, changes in accounting estimates and errors” (Effective for the accounting periods as of January 1, 2020) • Amendments to IFRS 9 “Financial instruments”, IAS 39 “Financial instruments: Recognition and Measurement” and IFRS 7 “Financial instruments: Disclosures” (Effective for the accounting periods as of January 1, 2020)—Interest Rate Benchmark Reform • On May 28, 2020, the IASB issued “Covid-19-Related Covid-19 Standards, interpretations and amendments issued but not yet effective The following pronouncements and related amendments are applicable for first quarter accounting periods beginning after January 1, 2021. We do not anticipate that the adoption of these pronouncements and amendments will have a material impact on our results of operations, financial position or cash flows. • IFRS 17 “Insurance Contracts” (Effective for accounting periods beginning after January 1, 2023 and not yet adopted by the European Union) • Amendments to IAS 37 – Onerous Contracts: Cost of Fulfilling a Contract (Effective for the accounting periods as of January 1, 2022) • Amendments to IAS 37 – Onerous Contracts: Cost of Fulfilling a Contract (Effective for the accounting periods as of January 1, 2022) • Amendments to IAS 16 – Property, Plant and Equipment: Proceeds before Intended Use (Effective for the accounting periods as of January 1, 2022) • Amendments to IFRS 3 – Reference to the Conceptual Framework (Effective for the accounting periods as of January 1, 2022) • Amendments to IFRS 9, IAS 39, IFRS 7, IFRS 4 and IFRS 16 – Interest Rate Benchmark Reform – Phase 2 (Effective for the accounting periods as of January 1, 2021)
IFRS16 application	2.2 IFRS16 application Since January 1, 2019, Cellectis has applied the new standard IFRS 16 “Leases”. Under this standard, a financial asset and a financial liability are recognized for Group leases that meet the standard’s criteria. The financial statements for prior periods have not been restated in accordance with the transition options of IFRS 16 elected by the Group since Cellectis has applied the modified retrospective approach. The Group uses the two capitalization exemptions provided by the standard: • lease contracts with a duration of less than 12 months; and • lease contracts for which the underlying asset has a low value, which has been defined by the Group to be below $5,000. The Group has also applied the following practical expedients at the transition date: • exclusion of initial direct costs from the measurement of the right-of-use • accounting for leases for which the lease term ends within 12 months of the date of initial application as short-term leases i.e. accounting for leases expenses in Profit and loss account; and • the carrying amount of the right-of-use The following discount rates have been applied: • building rental in Paris, France (discounting rate 2%), building rental in Roseville, Minnesota, USA and Raleigh, North Carolina, USA (discounting rate of 8%), building rental in New York, New York, USA (discounting rate of 4.4%), and equipment rental (discounting rate 1%). The main changes introduced by IFRS 16 are the following: Capitalization of the right-of-use Identified lease contracts mainly concern Cellectis’ Headquarters and R&D buildings in Paris, New York and Raleigh, North Carolina, USA and Calyxt’s Headquarters and its production and storage areas in Roseville, Minnesota, USA. For purposes of IFRS 16, the lease term reflects the Group’s reasonable expectation of the period during which the underlying asset will be used. The discount rate used to calculate the lease debt has been determined, for each portfolio of assets, according to the incremental borrowing rate at the transition date. The sale and lease-back agreement entered into by Calyxt in the third quarter of 2017 has a defined lease term and was classified as an operating lease agreement under IAS 17. According to IFRS 16, this lease receives the standard accounting treatment for operating leases existing at the date of initial application and the value of the right-of-use Accounting for the other assets leases: The main lease contracts identified correspond to office and laboratory equipment.
Currency of the financial statements	2.3 Currency of the financial statements The Consolidated Financial Statements are presented in U.S. dollars, which differs from the functional currency of Cellectis, which is the euro. All financial information (unless indicated otherwise) is presented in thousands of U.S. dollars. The statements of financial position of consolidated entities having a functional currency different from the U.S. dollar are translated into U.S. dollars at the closing exchange rate (spot exchange rate at the statement of financial position date) and the statements of operations, statements of comprehensive income (loss) and statements of cash flow of such consolidated entities are translated at the average period to date exchange rate. The resulting translation adjustments are included in equity under the caption “Currency Translation Adjustments” in the Consolidated Statements of Changes in Shareholders’ Equity.
Basis of consolidation	2.4 Basis of consolidation Going concern The consolidated financial statements were prepared on a going concern basis. With cash and cash equivalents of $241,148 thousand as of December 31, 2020, the Company believes it has sufficient resources to continue operating for at least twelve months following the consolidated financial statements’ publication. Accounting policy We control all the legal entities included in the consolidation. An investor controls an investee when the investor is exposed to variable returns from its involvement with the investee, and has the ability to affect those returns through its power over the investee. Control requires power, exposure to variability of returns and a linkage between the two. To have power, the investor needs to have existing rights that give it the current ability to direct the relevant activities that significantly affect the investee’s returns. In order to ascertain control, potential voting rights which are substantial are taken into consideration. Consolidation of a subsidiary begins when the Group obtains control over the subsidiary and ceases when the Group loses control of the subsidiary. All intra-group assets and liabilities, equity, income, expenses and cash flows relating to transactions between members of the Group are eliminated in full consolidation. Consolidated entities For the year ended December 31, 2020, the consolidated group of companies (sometimes referred to as the “Group”) includes Cellectis S.A., Cellectis, Inc., Cellectis Biologics Inc., which was incorporated on January 18, 2019, and Calyxt. As of December 31, 2020, Cellectis S.A. owns 100% of Cellectis, Inc., which owns 100% of Cellectis Biologics, Inc., and approximately 64.7% of Calyxt’s outstanding shares of common stock. As of December 31, 2019, Cellectis S.A. owned 100% of Cellectis, Inc. and approximately 68.9% of Calyxt’s outstanding shares of common stock. Until July 25, 2017, Cellectis S.A. fully owned Calyxt. On July 25, 2017, Calyxt closed its IPO with $64.4 million in gross proceeds to Calyxt from the sale of 8,050,000 shares at $8 per share, including the full exercise of the underwriter’s over-allotment option and Cellectis’ purchase of $20.0 million of shares in the IPO. On May 22, 2018, Calyxt completed a follow-on follow-on follow-on SEC-registered, Non-controlling Non-controlling non-controlling follow-on
Foreign currency	2.5 Foreign currency Foreign currency transactions and balances Significant transactions in foreign currencies are translated into the respective functional currencies at the exchange rates effective at the transaction dates, otherwise the average rate of the previous month is used for non-significant The resulting exchange gains or losses are recorded in the consolidated statements of operations in financial gain (loss). Foreign currency translation The assets and liabilities of foreign operations having a functional currency different from the euro are translated into euros at the period end exchange rate. The income and expenses of foreign operations are translated into euros using the average exchange rate for the reporting period. Gains and losses arising from currency translation are recognized in other comprehensive loss. Consolidated financial statements are then converted into dollars using the method described in Note 2.3. The difference in effect of exchange rate changes on cash and cash equivalents between the statements of consolidated operations and consolidated cash flows is mainly explained by the following elements: • the differential between the average exchange rate and the period end rates applied to the cash flows of the period; • the differential between the opening exchange rates and the period end exchanges rate applied on our opening cash and cash equivalents balance denominated in dollars; and • the foreign exchange rate impact of the conversion of the financial statements of our US subsidiaries.
Use of judgment, estimates and assumptions	2.6 Use of judgment, estimates and assumptions The preparation of these consolidated financial statements requires management to make judgments, estimates and assumptions that affect the reported amounts of revenues, expenses, assets and liabilities, and the accompanying disclosures, including the disclosure of contingent liabilities. Actual amounts may differ from those estimates. The Group’s exposure to risks and uncertainties is disclosed in Note 8.3: Financial instruments risk management and policies. Estimates and assumptions The key assumptions concerning the future and other key sources of estimation uncertainty at the period end date, that have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year, are described below. The Group based its assumptions and estimates on parameters available when the consolidated financial statements were prepared. Existing circumstances and assumptions about future developments, however, may change due to market changes or circumstances arising that are beyond the control of the Group. Such changes are reflected in the assumptions when they occur. • Revenue recognition – Note 3.1 • Share-based payments – Note 16 • Provisions for risks and charges – Note 18 • Right-of-use

Information concerning the Gr_2

Information concerning the Group's Consolidated Operations (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Revenues By Country of Origin and Other Income	Revenues by country of origin and other income For the year ended December 31, 2018 2019 2020 From France 12,495 7,896 51,057 From USA 236 7,294 22,892 Revenues 12,731 15,190 73,949 Research tax credit 8,561 7,800 8,433 Subsidies and other 140 — 74 Other income 8,701 7,800 8,507 Total revenues and other income 21,432 22,990 82,456
Revenues by Nature	Revenues by nature For the year ended December 31, 2018 2019 2020 $ in thousands Recognition of previously deferred upfront payments 7,114 — 20,291 Other revenues 3,383 6,055 28,532 Collaboration agreements 10,497 6,055 48,823 Licenses 2,142 1,762 2,123 Products & services 92 7,373 23,003 Total revenues 12,731 15,190 73,949
Details of Operating Expenses by Nature	Details of operating expenses by nature For the year ended December 31, 2018 2019 2020 $ in thousands Cost of revenue Cost of goods sold (1) — (9,280 ) (34,168 ) Royalty expenses (2,739 ) (2,112 ) (2,107 ) Cost of revenue (2,739 ) (11,392 ) (36,275 ) For the year ended December 31, 2018 2019 2020 $ in thousands Research and development expenses Wages and salaries (16,452 ) (21,294 ) (29,818 ) Social charges on stock option grants (99 ) (1,357 ) (56 ) Non-cash (18,057 ) (12,260 ) (8,029 ) Personnel expenses (34,608 ) (34,911 ) (37,903 ) Purchases and external expenses (40,458 ) (49,251 ) (41,270 ) Other (1,501 ) (7,880 ) (7,777 ) Total research and development expenses (76,567 ) (92,042 ) (86,950 ) For the year ended December 31, 2018 2019 2020 $ in thousands Selling, general and administrative expenses Wages and salaries (11,373 ) (12,822 ) (15,794 ) Social charges on stock option grants (29 ) (491 ) (23 ) Non-cash (19,161 ) (14,621 ) (8,707 ) Personnel expenses (30,563 ) (27,934 ) (24,524 ) Purchases and external expenses (14,251 ) (11,431 ) (15,358 ) Other (2,433 ) (3,652 ) (4,319 ) Total selling, general and administrative expenses (47,248 ) (43,017 ) (44,201 ) For the year ended December 31, 2018 2019 2020 $ in thousands Personnel expenses Wages and salaries (27,825 ) (34,116 ) (45,612 ) Social charges on free shares and stock option grants (128 ) (1,848 ) (79 ) Non-cash (37,218 ) (26,881 ) (16,736 ) Total personnel expenses (65,171 ) (62,845 ) (62,427 ) (1) Corresponds to the Calyxt costs of goods sold decreased by transportation costs related to Archer Daniels Midland (ADM) sales, considered as prepaid expenses under IFRS 15.
Details of Financial Income and Expenses	Details of financial income and expenses For the year ended December 31, 2018 2019 2020 Interest income 6,787 6,985 1,949 Foreign exchange gain 13,597 4,481 3,155 Other financial revenues 188 505 364 Total financial revenues 20,572 11,971 5,468 Interest expenses (39 ) (3 ) (43 ) Interest expenses for leases (7 ) (2,603 ) (3,557 ) Foreign exchange loss (3,090 ) (671 ) (13,885 ) Other financial expenses (677 ) (354 ) (29 ) Total financial expenses (3,813 ) (3,631 ) (17,514 ) Total 16,758 8,340 (12,046 )
Disclosure of Income Tax (Expense or Income)	Tax proof For the year ended December 31, 2018 2019 2020 in thousands Income (loss) before taxes from continuing operations (88,333 ) (115,212 ) (97,483 ) Theoretical group tax rate 23.66 % 25.35 % 24.88 % Theoretical tax benefit (expense) 20,901 29,208 24,254 Increase/ decrease in tax benefit arising from: Permanent differences 832 (1,131 ) (1,141 ) Research tax credit 2,079 2,786 3,245 Share-based compensation & other IFRS adjustments (8,065 ) (7,828 ) (4,198 ) Non recognition of deferred tax assets related to tax losses and temporary differences (15,652 ) (23,079 ) (22,159 ) Other differences (95 ) 43 0 Effective tax expense — — — Effective tax rate 0.00 % 0.00 % 0.00 %
Disclosure of Deferred Tax Assets and Liabilities	Deferred tax assets and liabilities As of December 31, 2018 2019 2020 $ in thousands Credits and net operating loss carryforwards 65,555 102,112 141,954 Pension commitments 569 714 1,003 Leases (4 ) 47 319 Impairment of assets 10 1 1 Revenue recognition 200 197 (491 ) Other 491 284 1,308 Total unrecognized deferred tax assets, net (66,823 ) (103,354 ) (144,095 )
Summary of Key Performance Indicators by Reportable Segments	Details of key performance indicators by reportable segment For the year ended December 31, 2018 For the year ended December 31, 2019 For the year ended December 31, 2020 ( ) Plants Therapeutics Total Plants Therapeutics Total Plants Therapeutics Total External revenues 236 12,495 12,731 7,294 7,896 15,190 22,892 51,057 73,949 External other income 178 8,523 8,701 — 7,800 7,800 — 8,507 8,507 External revenues and other income 414 21,018 21,432 7,294 15,696 22,990 22,892 59,564 82,456 Cost of revenue (595 ) (2,144 ) (2,739 ) (9,275 ) (2,117 ) (11,392 ) (34,324 ) (1,951 ) (36,275 ) Research and development expenses (8,638 ) (67,929 ) (76,567 ) (12,390 ) (79,652 ) (92,042 ) (9,903 ) (77,048 ) (86,951 ) Selling, general and administrative expenses (21,067 ) (26,180 ) (47,248 ) (26,090 ) (16,927 ) (43,017 ) (21,688 ) (22,513 ) (44,201 ) Other operating income and expenses (50 ) 81 31 25 (116 ) (91 ) (103 ) (363 ) (466 ) Total operating expenses (30,351 ) (96,172 ) (126,523 ) (47,730 ) (98,812 ) (146,542 ) (66,018 ) (101,875 ) (167,893 ) Operating income (loss) before tax (29,937 ) (75,154 ) (105,091 ) (40,436 ) (83,116 ) (123,552 ) (43,126 ) (42,311 ) (85,437 ) Financial gain (loss) 1,420 15,339 16,758 294 8,045 8,340 (776 ) (11,270 ) (12,046 ) Net income (loss) (28,517 ) (59,816 ) (88,333 ) (40,142 ) (75,071 ) (115,212 ) (43,902 ) (53,581 ) (97,483 ) Non controlling interests 9,640 — 9,640 13,121 — 13,121 16,409 — 16,409 Net income (loss) attributable to shareholders of Cellectis (18,877 ) (59,816 ) (78,693 ) (27,021 ) (75,071 ) (102,091 ) (27,493 ) (53,581 ) (81,074 ) R&D non-cash 838 16,852 17,689 1,619 10,010 11,629 801 6,790 7,591 SG&A non-cash 5,218 11,655 16,873 6,673 4,940 11,613 3,536 3,238 6,774 Adjustment of share-based compensation attributable to shareholders of Cellectis 6,056 28,507 34,563 8,292 14,950 23,242 4,337 10,028 14,365 Adjusted net income (loss) attributable to shareholders of Cellectis (12,821 ) (31,309 ) (44,130 ) (18,729 ) (60,121 ) (78,849 ) (23,156 ) (43,553 ) (66,709 ) Depreciation and amortization (637 ) (1,740 ) (2,377 ) (1,233 ) (5,642 ) (6,875 ) (1,869 ) (7,950 ) (9,819 ) Additions to tangible and intangible assets 1,871 3,040 4,911 2,998 14,668 17,666 1,786 48,813 50,599

Intangible assets (Tables)

Intangible assets (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Details Information About Intangible Assets	Details of intangible assets $ in thousands Software and Patents Assets under construction Total Net book value as of January 1, 2018 811 619 1,431 Additions to intangible assets 14 103 117 Disposal of intangible assets (7 ) — (7 ) Reclassification 6 — 6 Depreciation expense (217 ) — (217 ) Translation adjustments (30 ) (31 ) (61 ) Net book value as of December 31, 2018 577 691 1,268 Gross value at end of period 2,454 691 3,146 Accumulated depreciation and impairment at end of period (1,878 ) — (1,878 ) Net book value as of January 1, 2019 577 691 1,268 Additions to intangible assets 84 (2 ) 82 Disposal of intangible assets (50 ) — (50 ) Reclassification 6 — 6 Depreciation expense (174 ) — (174 ) Translation adjustments (12 ) (12 ) (24 ) Net book value as of December 31, 2019 431 677 1,108 Gross value at end of period 2,448 677 3,125 Accumulated depreciation and impairment at end of period (2,017 ) — (2,017 ) Net book value as of January 1, 2020 431 677 1,108 Additions to intangible assets 558 (41 ) 517 Disposal of intangible assets — — — Reclassification 76 — 76 Depreciation expense (206 ) — (206 ) Translation adjustments 30 59 89 Net book value as of December 31, 2020 889 695 1,584 Gross value at end of period 3,309 695 4,004 Accumulated depreciation and impairment at end of period (2,419 ) — (2,419 )

Right-of-use assets (Tables)

Right-of-use assets (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Disclosure Of Detailed Information About Breakdown Of Right Of Use Assets Explanatory	The breakdown of right-of-use Building lease Office and Total $ in thousands Net book value as of January 1, 2019 36,061 1,508 37,569 Additions 11,357 1,516 12,873 Depreciation expense (4,058 ) (520 ) (4,578 ) Translation adjustments (248 ) (4 ) (252 ) Net book value as of December 31, 2019 43,112 2,500 45,612 Gross value at end of period 47,175 3,153 50,328 Accumulated depreciation at end of period (4,063 ) (653 ) (4,716 ) Net book value as of January 1, 2020 43,112 2,500 45,612 Additions 24,719 8,369 33,088 Depreciation expense (4,904 ) (1,568 ) (6,472 ) Translation adjustments 1,699 (82 ) 1,617 Net book value as of December 31, 2020 64,626 9,219 73,845 Gross value at end of period 73,878 11,511 85,389 Accumulated depreciation at end of period (9,252 ) (2,292 ) (11,544 )

Property, plant and equipment (

Property, plant and equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Summary of Property Plant and Equipment Estimated Useful Lives	The estimated useful lives are as follows: • Buildings and other outside improvements 10-20 • Leasehold improvements 5-10 • Office furniture 10 years • Laboratory equipment 3-10 • Office equipment 5 years • IT equipment 3 years
Details of Property, Plant and Equipment	Details of property, plant and equipment Lands and Technical Fixtures, Assets under Total $ in thousands Net book value as of January 1, 2018 3,159 2,505 753 809 7,226 Additions to tangible assets 879 1,622 1,820 1,942 6,263 Disposal of tangible assets — (49 ) (690 ) (426 ) (1,164 ) Reclassification 39 216 793 (1,053 ) (6 ) Depreciation expense (758 ) (854 ) (478 ) — (2,091 ) Translation adjustments (90 ) (46 ) (27 ) (25 ) (188 ) Net book value as of December 31, 2018 3,229 3,393 2,172 1,247 10,041 Gross value at end of period 7,604 13,297 3,215 2,045 26,160 Accumulated depreciation and impairment at end of period (4,375 ) (9,903 ) (1,043 ) (798 ) (16,119 ) Net book value as of January 1, 2019 3,229 2,084 2,172 1,247 8,732 Additions to tangible assets 318 374 329 16,563 17,584 Disposal of tangible assets — (10 ) (1 ) (419 ) (430 ) Reclassification 15 1,974 630 (2,624 ) (5 ) Depreciation expense (192 ) (1,247 ) (684 ) — (2,123 ) Translation adjustments (40 ) (15 ) (11 ) 20 (46 ) Net book value as of December 31, 2019 3,330 3,160 2,435 14,787 23,712 Gross value at end of period 7,833 13,962 4,149 15,585 41,529 Accumulated depreciation and impairment at end of period (4,503 ) (10,802 ) (1,714 ) (798 ) (17,817 ) Net book value as of January 1, 2020 3,330 3,160 2,435 14,787 23,712 Additions to tangible assets 5,248 2,034 854 41,946 50,082 Disposal of tangible assets 4 (122 ) — — (118 ) Reclassification 8,258 692 670 (9,696 ) (76 ) Depreciation expense (817 ) (1,464 ) (861 ) — (3,141 ) Translation adjustments 742 136 73 264 1,215 Net book value as of December 31, 2020 16,765 4,436 3,171 47,301 71,673 Gross value at end of period 22,518 17,381 5,843 47,301 93,043 Accumulated depreciation and impairment at end of period (5,752 ) (12,946 ) (2,672 ) (0 ) (21,370 )

Financial assets and liabilit_2

Financial assets and liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Summary of Financial Assets and Liabilities	The following table shows the carrying amounts and fair values of financial assets and financial liabilities. Accounting category Book value on the Fair Value 2019 Fair value through profit and loss Amortized cost $ in thousands Financial assets Non-current — 5,517 5,517 5,517 Trade receivables — 2,959 2,959 2,959 Subsidies receivables — 9,140 9,140 9,140 Current financial assets — 20,385 20,385 20,385 Cash and cash equivalents 340,522 — 340,522 340,522 Total financial assets 340,522 38,001 378,523 378,523 Financial liabilities Non-current — 46,540 46,540 46,540 Lease debts — 1,067 1,067 1,067 Trade payables — 29,264 29,264 29,264 Other current liabilities — 8,497 8,497 8,497 Total financial liabilities — 85,368 85,368 85,368 Accounting category Book value on the Fair Value 2020 Fair value through Amortized cost $ in thousands Financial assets Non-current — 7,007 7,007 7,007 Trade receivables — 5,171 5,171 5,171 Subsidies receivables — 10,703 10,703 10,703 Current financial assets — 27,091 27,091 27,091 Cash and cash equivalents 241,148 — 241,148 241,148 Total financial assets 241,148 49,972 291,120 291,120 Financial liabilities Non-current — 75,764 75,764 75,764 Other non-current — 28,836 28,836 28,836 Current lease debts — 6,696 6,696 6,696 Trade payables — 24,609 24,609 24,609 Other current liabilities — 19,127 19,127 19,127 Total financial liabilities — 155,032 155,032 155,032

Trade receivables and other c_2

Trade receivables and other current assets (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Disclosure of Trade Receivables	10.1 Trade receivables As of December 31, As of December 31, 2019 2020 $ in thousands Trade receivables 3,513 5,787 Valuation allowance (554 ) (616 ) Total net value of trade receivables 2,959 5,171
Disclosure of Subsidies Receivables	10.2 Subsidies receivables As of December 31, As of December 31, 2019 2020 $ in thousands Research tax credit 9,140 10,703 Total subsidies receivables 9,140 10,703
Disclosure of Other Current Assets	10.3 Other current assets As of December 31, As of December 31, 2019 2020 $ in thousands VAT receivables 3,044 3,093 Prepaid expenses and other prepayments 11,829 14,113 Tax and social receivables 150 227 Deferred expenses and other current assets 594 12,210 Total other current assets 15,617 29,643

Current financial assets and _2

Current financial assets and Cash and cash equivalents (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Summary of Current Financial Assets and Cash and Cash Equivalents	As of December 31, 2019 Carrying amount Unrealized Gains/(Losses) Estimated fair value $ in thousands Current financial assets 20,385 — 20,385 Cash and cash equivalents 340,522 — 340,522 Current financial assets and cash and cash equivalents 360,907 — 360,907 As of December 31, 2020 Carrying amount Unrealized Gains/(Losses) Estimated fair value $ in thousands Current financial assets 27,091 — 27,091 Cash and cash equivalents 241,148 — 241,148 Current financial assets and cash and cash equivalents 268,239 — 268,239
Details of Cash and Cash Equivalents	Details of cash and cash equivalents As of December 31, As of December 31, 2019 2020 $ in thousands Cash and bank accounts 270,630 164,586 Money market funds 13,722 13,977 Fixed bank deposits 56,170 62,585 Total cash and cash equivalents 340,522 241,148

Financial liabilities (Tables)

Financial liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Detail of financial liabilities	12.1 Detail of financial liabilities As of December 31, As of December 31, 2019 2020 $ in thousands Lease debts 46,540 75,764 State Guaranteed loan « PGE » — 22,701 PPP loan 1,518 Other non-current — 4,617 Total non-current 46,540 104,600 Lease debts 1,067 6,696 Total current financial liabilities 1,067 6,696 Trade payables 29,264 24,609 Other current liabilities 8,497 19,127 Total Financial liabilities 85,368 155,032
Due dates of the financial liabilities	12.2 Due dates of the financial liabilities Balance as of December 31, 2020 Book Value Less than One One to Five More than Five $ in thousands Lease debts 82,460 6,696 30,706 45,058 Other financial liabilities 28,836 78 24,698 4,061 Financial liabilities 111,296 6,774 55,404 49,118 Trade payables 24,609 24,609 — — Other current liabilities 19,127 19,127 — — Total financial liabilities 155,032 50,510 54,404 49,118

Other current liabilities (Tabl

Other current liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Summary of Other Current Liabilities	As of December 31, As of December 31, 2019 2020 $ in thousands VAT Payables 130 81 Accruals for personnel related expenses 7,295 13,235 Other 1,072 6,077 Total 8,497 19,393

Deferred revenues and contrac_2

Deferred revenues and contract liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Details of Deferred Revenues and Contract Liabilities	Details of deferred revenues and deferred income As of December 31, 2019 As of December 31, 2020 $ in thousands Deferred revenues and contract liabilities 20,033 452 Others — — Total Deferred revenue and contract liabilities 20,033 452

Capital (Tables)

Capital (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Schedule of Classes of Share Capital	Nature of the Transactions Share Capital Share premium Number of shares Nominal value $ in thousands in $ Balance as of January 1, 2018 2,367 614,037 35,960,062 0.05 Capital Increase 379 178,230 6,146,000 — Exercise of share warrants, employee warrants and stock options 19 7,751 324,007 — Non-cash — 28,507 — — Balance as of December 31, 2018 2,765 828,525 42,430,069 0.05 Capital Increase 2 — 35,600 — Exercise of share warrants, employee warrants and stock options — — — — Non-cash — 14,951 — — Other movements — 2 — Balance as of December 31, 2019 2,767 843,478 42,465,669 0.05 Exercise of share warrants, employee warrants and stock options 18 6,101 314,517 — Non-cash — 14,365 — — Other movements — (32 ) — Balance as of December 31, 2020 2,785 863,912 42,780,186 0.05
Schedule of Share Warrants and Non-employee Warrants	Date Type Number of Number of Number of Number of Number of Maximum of shares Number of Strike price per 07/27/2010 BSPCE 19,702 — 19,702 — — — — 7.97 03/24/2015 Stock Options 1,612,994 — — 21,391 1,591,603 1,591,603 1,591,603 38.45 03/27/2015 BSA 130,000 — — — 130,000 130,000 130,000 38.45 05/18/2015 BSA 50,000 — — — 50,000 50,000 50,000 29.58 09/08/2015 BSA 224,200 — — — 224,200 224,200 224,200 28.01 09/08/2015 Stock Options 1,623,200 — — 24,500 1,598,700 1,598,700 1,598,700 27.55 03/14/2016 BSA 147,025 — — 147,025 147,025 147,025 27.37 03/14/2016 Stock Options 1,652,595 — 2,354 13,536 1,636,705 1,636,705 1,636,705 22.44 10/28/2016 BSA 148,000 — — 148,000 148,000 148,000 18.68 10/28/2016 Stock Options 2,178,893 238,660 21,599 1,918,634 1,918,634 1,918,634 17.90 10/11/2017 BSA 200,000 — — — 200,000 200,000 200,000 24.34 10/11/2017 Stock Options 960,000 — 1,000 35,000 924,000 924,000 707,722 22.57 10/08/2018 Free shares 3,000 — 3,000 — — — — 23.84 10/08/2018 Stock Options 50,000 — — 30,000 20,000 20,000 9,996 24.80 12/17/2018 Free shares 13,000 — — 13,000 — — — 16.00 12/17/2018 Stock Options 40,000 — — 40,000 — — — 18.37 03/07/2019 Free shares 2,500 — — — 2,500 2,500 — 16.00 04/24/2019 Stock Options 1,469,700 — 41,539 162,646 1,265,515 1,265,515 531,538 18.25 04/24/2019 Free shares 6,500 — — — 6,500 6,500 — 18.01 07/16/2019 Free shares 4,000 — — — 4,000 4,000 — 14.01 11/06/2019 Stock Options 55,000 — — 25,000 30,000 30,000 7,500 11.06 11/06/2019 Free shares 21,500 — — 6,500 15,000 15,000 — 11.32 11/18/2019 Stock Options 30,000 — 7,500 — 22,500 22,500 — 12.33 11/18/2019 Free shares 16,500 — — — 16,500 16,500 — 12.16 03/04/2020 Free shares — 6,500 — — 6,500 6,500 — 14.54 04/14/2020 Free shares — 20,000 — — 20,000 20,000 — 9.14 04/14/2020 Stock Options — 160,000 — — 160,000 160,000 — 8.27 06/19/2020 Free shares — 16,500 — — 16,500 16,500 — 14.76 06/19/2020 Stock Options — 17,000 — — 17,000 17,000 — 15.84 07/20/2020 Free shares — 10,000 — — 10,000 10,000 — 15.76 07/20/2020 Stock Options — 17,000 — — 17,000 17,000 — 15.12 08/05/2020 Free shares — 70,000 — — 70,000 70,000 — 14.00 08/05/2020 Stock Options — 212,000 — — 212,000 212,000 — 14.62 09/11/2020 Free shares — 15,000 — — 15,000 15,000 — 14.58 09/11/2020 Free shares — 6,500 — — 6,500 6,500 — 14.98 09/11/2020 Stock Options — 45,000 — — 45,000 45,000 — 14.36 10/14/2020 Free shares — 423,285 — 6,535 416,750 416,750 — 22.45 11/05/2020 Stock Options — 28,000 — — 28,000 28,000 — 14.62 11/05/2020 Free shares — 16,600 — — 16,600 16,600 — 14.76 12/16/2020 Free shares — 7,300 — — 7,300 7,300 — 23.75 Total 10,658,309 1,070,685 313,755 399,707 11,015,532 11,015,532 8,901,623
Schedule of Information Relating to Subsidiaries that Reported Non-Controlling Interest	The following table summarizes the information relating to each of our subsidiaries that reported non-controlling CALYXT 2019 2020 $ in thousands Revenue 7,294 22,892 Net Profit (Loss) (40,142 ) (43,902 ) Net Profit (Loss) attributable to NCI (13,121 ) (16,409 ) Other comprehensive income (1,237 ) (1,196 ) Total comprehensive income (41,378 ) (45,098 ) Total comprehensive income attributable to NCI (12,856 ) (15,942 ) Current assets 63,528 39,590 Non-current 22,518 23,737 Current liabilities 6,642 6,945 Non-current 15,121 19,507 Net assets 64,283 36,875 Net assets attributable to NCI 19,973 13,035

Share-based payments (Tables)

Share-based payments (Tables)	12 Months Ended
	Dec. 31, 2020
Statement [Line Items]
Summary of Number of Shares Outstanding and Weighted Average Grant Date Fair Value	Information on free shares activity follows: Number of Free Weighted- Unvested balance at December 31, 2018 71,600 27.37 € Granted 57,000 13.04 € Vested (35,600 ) 25.74 € Cancelled (26,000 ) 21.65 € Unvested balance at December 31, 2019 67,000 13.98 € Granted (1) 591,685 20.10 € Vested (3,000 ) 23.84 € Cancelled (26,035 ) 16.45 € Unvested balance at December 31, 2020 629,650 19.59 € (1) 423,285 free shares have been granted in October 2020 under the 2018 Stock Option Plan and are under non-market performance vesting condition s t hese shares were voided as of December 31, 2020.
Warrants [member]
Statement [Line Items]
Summary of Information on Stock Option Activity	Information on warrants activity follows: Warrants Weighted- Warrants Weighted- Remaining Balance as of December 31, 2018 687,252 27.74 € 918,927 26.74 € 7.2y Granted — — — — Exercised — — — — Forfeited or Expired — — — — Balance as of December 31, 2019 852,260 35.35 € 918,927 35.12 € 6.9y Granted — — — — Exercised — — (19,702 ) 8.28 € Forfeited or Expired — — — — Balance as of December 31, 2020 899,225 27.15 € 899,225 27.15 € 5.3y
Summary of assumptions Weighted-average Fair Values of Warrants Granted and Assumptions Used for Black-Scholes Option Pricing Model	The weighted-average fair values of warrants granted and the assumptions used for the Black-Scholes option pricing model were as follows: 2016 2017 Weighted-Average fair values of warrants granted 9.33€ 13.20€ Assumptions: Risk-free interest rate 0.00% - 0.12% Share entitlement per options 1 1 Exercise price 18.68€ - 27.37€ 24.34€ Grant date share fair value 16.42€ - 22.48€ 24.95€ Expected volatility 62.8% - 63.1% 64.7% Expected term (in years) 6 6 Vesting conditions Service Service Vesting period Graded Graded
Stock options [member]
Statement [Line Items]
Summary of Information on Stock Option Activity	Information on stock option activity follows: Options Weighted- Options Weighted- Remaining Balance as of December 31, 2018 5,644,044 27.47 € 8,978,106 25.36 € 7.3y Granted — — € 1,650,800 17.90 € Exercised — — € 0 0.00 € Forfeited or Expired — — € (956,524 ) 24.01 € Balance as of December 31, 2019 6,922,172 26.30 € 9,672,382 24.22 € 6.8y Granted — — € 479,000 12.54 € Exercised — — € (291,053 ) 17.86 € Forfeited or Expired — — € (373,672 ) 20.61 € Balance as of December 31, 2020 8,002,398 25.28 € 9,486,657 23.97 € 5.9y
Summary of assumptions Vesting Details	The weighted-average fair values of stock options granted and the assumptions used for the Black-Scholes option pricing model were as follows: 2018 2019 2020 Weighted-Average fair values of stock options granted 8.84€ 10.19€ 7.40€ Assumptions: Risk-free interest rate 0.13% - 0.21% -0.38% - 0.09% 0.00% Share entitlement per options 1 1 1 Exercise price 18.37€ - 24.80€ 11.06€ - 18.25€ 8.27€ - 15.84€ Grant date share fair value 16€ - 17.78€ 11.32€ - 17.80€ 9.14€ - 15.76€ Expected volatility 63.3% - 63.4% 63.8% - 66.6% 61.3% - 62.8% Expected term (in years) 6.25 6.15 - 6.25 6.15 Vesting conditions Service Service Service Vesting period Graded Graded Graded
Stock options [member] | Calyxt Inc. [member]
Statement [Line Items]
Summary of Information on Stock Option Activity	Information on stock option activity follows: Options Weighted- Options Weighted- Remaining Balance as of December 31, 2018 1,278,038 $ 7.45 3,201,887 $ 10.67 8.2y Granted — — 1,590,000 $ 13.80 Exercised — — (95,327 ) $ 3.61 Forfeited or Expired — — (227,696 ) $ 14.68 Other activity 12,495 $ 13.29 Balance as of December 31, 2019 1,789,567 $ 8.73 4,481,359 $ 11.73 6.8y Granted — — 887,765 $ 4.67 Exercised — — (58,575 ) $ 3.60 Forfeited or Expired — — (689,376 ) $ 12.89 Balance as of December 31, 2020 2,347,665 $ 10.15 4,621,173 $ 10.30 7.3y
Summary of assumptions Vesting Details	The estimated fair values of stock options granted and the assumptions used for the Black-Scholes option pricing model were as follows: 2018 2019 2020 Weighted-Average fair values of stock options granted $9.09 $10.18 $3.24 Assumptions: Risk-free interest rate 2.2% - 3% 1.7% - 2.5% 0.3% - 1.7% Share entitlement per options 1 1 1 Exercise price $14.24 - $23.39 $4.05 - $15.39 $3.22 - $7.30 Grant date share fair value $14.24 - $23.39 $4.05 - $15.39 $3.22 - $7.30 Expected volatility 40.9% - 57.2% 52.6% - 78.9% 77.4% - 81.2% Expected term (in years) 5.6 - 10.0 6.8 - 10.0 6.0 - 10.0 Vesting conditions Service Service Service Vesting period Graded Graded Graded
Restricted Stock Unit [Member] | Calyxt Inc. [member]
Statement [Line Items]
Summary of Information on Stock Option Activity	Information on restricted stock unit activity follows: Number of Weighted- Unvested balance at December 31, 2018 1,051,414 $ 14.11 Granted 100,000 $ 12.48 Vested (324,043 ) $ 9.69 Cancelled (13,845 ) $ 12.72 Unvested balance at December 31, 2019 813,526 $ 10.31 Granted 105,633 $ 6.54 Vested (309,693 ) $ 10.08 Cancelled (61,659 ) $ 10.80 Unvested balance at December 31, 2020 547,807 $ 9.49
Performance Stock Unit [Member] | Calyxt Inc. [member]
Statement [Line Items]
Summary of Information on Stock Option Activity	Information on performance stock unit activity follows: Number of Weighted-Average Unvested balance at December 31, 2019 311,667 $ 7.06 Granted — — Vested — — Cancelled — — Unvested balance at December 31, 2020 311,667 $ 7.06
Summary of assumptions Detail Of Stock Unit Activity Performance Stock	The fair value of the performance stock units and the assumptions used for the Monte Carlo simulation were as follows: Date of grant 06/28/2019 Estimated fair values of performance stock units granted $ 7.06 Assumptions: Risk-free interest rate 1.71 % Expected volatility 75.0 % Expected term (in years) 3.0 years

Earnings per share (Tables)

Earnings per share (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Earnings per share	Detail of earnings per share For the year ended December 31, 2018 2019 2020 Net income (loss) attributable to shareholders of Cellectis ($ in thousands) (78,693 ) (102,091 ) (81,074 ) Adjusted weighted average number of outstanding shares, used to calculate both basic and diluted net result per share 40,774,197 42,442,136 42,503,447 Basic / Diluted net income (loss) per share attributable to shareholders of Cellectis Basic net income (loss) attributable to shareholders of Cellectis per share ( $ /share) (1.93 ) (2.41 ) (1.91 ) Diluted net income (loss) attributable to shareholders of Cellectis per share ( $ /share) (1.93 ) (2.41 ) (1.91 )

Provisions (Tables)

Provisions (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Details of Provisions	Details of provisions 01/01/2019 as restated Reclassification Additions Amounts used Reversals OCI 12/31/2019 $ in thousands Pension 2,278 — 314 — — 263 2,855 Loss on contract — 1,043 690 (1,461 ) — — 272 Employee litigation 41 — 715 (43 ) (75 ) 1 639 Commercial litigation 850 — 2,604 (595 ) (17 ) (11 ) 2,832 Total 3,169 1,043 4,323 (2,099 ) (92 ) 253 6,598 Non-current 2,278 314 — — 263 2,855 Current provisions 891 1,043 4,009 (2,099 ) (92 ) (10 ) 3,743 01/01/2020 Additions Amounts used Reversals OCI 12/31/2020 Pension 2,855 410 — — 745 4,010 Loss on contract 272 — (272 ) — — — Employee litigation 639 229 (308 ) (49 ) 49 560 Commercial litigation 2,832 329 (1,692 ) (985 ) 86 571 Total 6,598 968 (2,272 ) (1,034 ) 881 5,141 Non-current 2,855 410 — — 745 4,010 Current provisions 3,743 558 (2,272 ) (1,034 ) 136 1,131 * As of January 1, 2019, Montvale, New Jersey facility lease agreement provision for loss on contract was scoped under IFRS 16 and classified as lease debts. During the period, the agreement has been discontinued which changed its treatment placing it outside the scope of IFRS 16 and resulting in the reclassification to “loss on contract” presented above.
Schedule of Estimation of Retirement Indemnity to Employee	As part of the estimation of the retirement indemnity to employee, the following assumptions were used for all categories of employees: 2018 2019 2020 % social security contributions 45.00% 45.00% 45.00% Salary increases 3.50% 3.50% 3.50% Discount rate 1.75% 1.00% 0.68% Terms of retirement voluntary retirement Retirement age 65 years old 65 years old 65 years old
Summary of Net Defined Benefit Liability and Components	The following table shows reconciliation from the opening balances to the closing balances for net defined benefit liability and its components. $ in thousands As of January 1, 2018 (2,194 ) Current service cost (276 ) Interest cost (38 ) Benefit paid 54 Actuarial gains and losses 70 Reclassification/CTA 105 As of December 31, 2018 (2,278 ) Current service cost (275 ) Interest cost (39 ) Benefit paid Actuarial gains and losses (303 ) Reclassification/CTA 40 As of December 31, 2019 (2,855 ) Current service cost (381 ) Interest cost (29 ) Benefit paid Actuarial gains and losses (411 ) Reclassification/CTA (334 ) As of December 31, 2020 (4,010 )

Commitments (Tables)

Commitments (Tables)	12 Months Ended
	Dec. 31, 2020
Text block1 [abstract]
Details of commitments	Details of commitments As of December 31, 2020 Total Less than 1 1 - 3 3 - 5 More than 5 $ in thousands License agreements 19,110 1,530 3,060 3,060 11,460 Manufacturing agreements 942 942 — — — Clinical & R&D agreements 1,353 946 408 — — Construction agreements 9,272 9,272 — — — Other agreements 21,704 21,631 72 — — Total commitments 52,381 34,321 3,540 3,060 11,460

Accounting Principles - Additio

Accounting Principles - Additional Information (Detail) - USD ($)	Oct. 20, 2020	Jun. 14, 2018	May 22, 2018	Jul. 25, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of changes in accounting estimates [line items]
Gross proceeds			$ 57,000,000	$ 64,400,000
Par value per share					$ 0.05	$ 0.05	$ 0.05
Shares to underwriters				20,000,000
Discounting Rate					1.00%
Equity value					$ 275,573,000	$ 315,123,000
Cash and cash equivalents					$ 241,148,000	$ 340,522,000	$ 451,501,000	$ 256,380,000
Paris [Member]
Disclosure of changes in accounting estimates [line items]
Discounting Rate					2.00%
Roseville [Member]
Disclosure of changes in accounting estimates [line items]
Discounting Rate					8.00%
Minnesota [Member]
Disclosure of changes in accounting estimates [line items]
Discounting Rate					8.00%
Raleigh [Member]
Disclosure of changes in accounting estimates [line items]
Discounting Rate					8.00%
North Carolina [Member]
Disclosure of changes in accounting estimates [line items]
Discounting Rate					8.00%
New York [Member]
Disclosure of changes in accounting estimates [line items]
Discounting Rate					4.40%
Top of Range [member] | IFRS 16 [Member]
Disclosure of changes in accounting estimates [line items]
Threshold limit of underlying asset					$ 5,000
Cellectis, Inc. [member]
Disclosure of changes in accounting estimates [line items]
Ownership interest in subsidiary					100.00%	100.00%
Calyxt Inc [member]
Disclosure of changes in accounting estimates [line items]
Ownership interest in subsidiary					64.70%	68.90%
Gross proceeds	$ 15,000,000		$ 57,000,000	$ 64,400,000
Common stock sold	3,750,000		4,057,500	8,050,000
Par value per share	$ 4		$ 15	$ 8
Shares to underwriters				$ 20,000,000
Selling price per common share	$ 4		$ 15
Common stock for exercising underwriters' option			457,500
Underwriting discounts and commissions			$ 3,200,000
Offering expense			$ 700,000
Non-controlling shareholders interest					35.30%	31.10%
Calyxt Inc [member] | IFRS 16 [Member]
Disclosure of changes in accounting estimates [line items]
Increase in right of used assets							$ 1,800,000
Calyxt Inc [member] | Cellectis, Inc. [member]
Disclosure of changes in accounting estimates [line items]
Purchase of common stock			550,000
Purchase of common shares	1,250,000
Equity value	$ 5,000,000
Purchase of common stock, value	$ 14,000,000
Calyxt Inc [member] | Cellectis [Member]
Disclosure of changes in accounting estimates [line items]
Purchase of common stock			550,000
Purchase of common stock, value		$ 1,200,000	$ 8,300,000
Purchase of common shares	1,250,000	63,175
Equity value	$ 5,000,000
Purchase of common stock, value	$ 14,000,000
Cellectis Biologics [Member]
Disclosure of changes in accounting estimates [line items]
Ownership interest in subsidiary					100.00%

Information Concerning the Gr_3

Information Concerning the Group's Consolidated Operations - Revenues by Country of Origin and Other Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of revenue [line items]
Revenues	$ 73,949	$ 15,190	$ 12,731
Research tax credit	8,433	7,800	8,561
Subsidies and other	74		140
Other income	8,507	7,800	8,701
Total revenues and other income	82,456	22,990	21,432
France [member]
Disclosure of revenue [line items]
Revenues	51,057	7,896	12,495
United States [member]
Disclosure of revenue [line items]
Revenues	$ 22,892	$ 7,294	$ 236

Information Concerning the Gr_4

Information Concerning the Group's Consolidated Operations - Revenues by Nature (Detail) - USD ($) $ in Thousands	Mar. 04, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of revenue [line items]
Recognition of previously deferred upfront payments	$ 19,400	$ 20,291		$ 7,114
Other revenues		28,532	$ 6,055	3,383
Collaboration agreements		48,823	6,055	10,497
Licenses		2,123	1,762	2,142
Products & services		23,003	7,373	92
Total revenues		$ 73,949	$ 15,190	$ 12,731

Information Concerning the Gr_5

Information Concerning the Group's Consolidated Operations - Additional Information (Detail) - USD ($)	Mar. 04, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated operations [line items]
Decrease (increase) in financial income and expenses			$ 8,400,000
Decrease (increase) in net foreign exchange gain		$ 1,300,000	6,700,000
Decrease (increase) in interest income and expenses		5,000,000	2,600,000	$ 0
Decrease (increase) in foreign exchange derivatives fair value adjustment		200,000	600,000	0
Net interest income			200,000	0
Other immaterial variances		300,000	100,000	0
Credits and net operating loss carryforwards		$ (141,954,000)	(102,112,000)	(65,555,000)
Carryforwards limit that can be offset against future taxable profit, additional percentage of profit exceeding the limit		50.00%
Products & services		$ 23,003,000	7,373,000	92,000
Decrease /increase in financial income		6,500,000
Foreign exchange gain		3,155,000	4,481,000	13,597,000
Decrease /increase in financial Expenses		13,900,000
Increase/ Decrease in foreign exchange losses		13,200,000
Net foreign exchange loss		13,885,000	671,000	3,090,000
Increase Decrease In Financial Expenses Lease Debt		1,000,000
Recognition of previously deferred upfront payments	$ 19,400,000	20,291,000		7,114,000
ALLO715 [Member]
Consolidated operations [line items]
Revenue from performance obligation		28,500,000	5,000,000
Top of Range [member]
Consolidated operations [line items]
Carryforwards limit that can be offset against future taxable profit		1,000,000
France [member]
Consolidated operations [line items]
Credits and net operating loss carryforwards		325,000,000	246,000,000	186,000,000
United States [member]
Consolidated operations [line items]
Credits and net operating loss carryforwards		$ 160,000,000	$ 162,000,000	$ 84,000,000
Client A [member]
Consolidated operations [line items]
Percentage of Revenue		64.00%	36.00%	55.00%
Client B [member]
Consolidated operations [line items]
Percentage of Revenue		25.00%	28.00%	21.00%
Calyxt [Member] | High Oleic Soyabean Oil [Member]
Consolidated operations [line items]
Products & services		$ 22,900,000
Calyxt [Member] | United States [member] | Indefinite Carry Forward [Member]
Consolidated operations [line items]
Credits and net operating loss carryforwards		64,000,000
Calyxt [Member] | United States [member] | 2032 and beyond [Member]
Consolidated operations [line items]
Credits and net operating loss carryforwards		41,900,000
Calyxt [Member] | US Subsidiaries [member] | 2019 [Member]
Consolidated operations [line items]
Credits and net operating loss carryforwards			$ 0
Calyxt [Member] | US Subsidiaries [member] | 2020 [Member]
Consolidated operations [line items]
Credits and net operating loss carryforwards		$ 0

Information Concerning the Gr_6

Information Concerning the Group's Consolidated Operations - Details of Operating Expenses by Nature (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Expense by nature [line Items]
Cost of good sold	$ (34,168)	$ (9,280)
Royalty expenses	(2,107)	(2,112)	$ (2,739)
Cost of revenue	(36,275)	(11,392)	(2,739)
Total research and development expenses	(86,950)	(92,042)	(76,567)
Total selling, general and administrative expenses	(44,201)	(43,017)	(47,248)
Research and Development Expenses [member]
Expense by nature [line Items]
Wages and salaries	(29,818)	(21,294)	(16,452)
Social charges on free shares and stock option grants	(56)	(1,357)	(99)
Non-cash stock based compensation expense	(8,029)	(12,260)	(18,057)
Personnel expenses	(37,903)	(34,911)	(34,608)
Purchases and external expenses	(41,270)	(49,251)	(40,458)
Other	(7,777)	(7,880)	(1,501)
Total research and development expenses	(86,950)	(92,042)	(76,567)
Personnel Expenses [member]
Expense by nature [line Items]
Wages and salaries	(45,612)	(34,116)	(27,825)
Social charges on free shares and stock option grants	(79)	(1,848)	(128)
Non-cash stock based compensation expense	(16,736)	(26,881)	(37,218)
Personnel expenses	(62,427)	(62,845)	(65,171)
Selling, General and Administrative Expenses [member]
Expense by nature [line Items]
Wages and salaries	(15,794)	(12,822)	(11,373)
Social charges on free shares and stock option grants	(23)	(491)	(29)
Non-cash stock based compensation expense	(8,707)	(14,621)	(19,161)
Personnel expenses	(24,524)	(27,934)	(30,563)
Purchases and external expenses	(15,358)	(11,431)	(14,251)
Other	(4,319)	(3,652)	(2,433)
Total selling, general and administrative expenses	$ (44,201)	$ (43,017)	$ (47,248)

Information Concerning the Gr_7

Information Concerning the Group's Consolidated Operations - Details of Financial Income and Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finance income expense [abstract]
Interest income	$ 1,949	$ 6,985	$ 6,787
Foreign exchange gain	3,155	4,481	13,597
Other financial revenues	364	505	188
Total financial revenues	5,468	11,971	20,572
Interest expenses	(43)	(3)	(39)
Interest expenses for leases	(3,557)	(2,603)	(7)
Foreign exchange loss	(13,885)	(671)	(3,090)
Other financial expenses	(29)	(354)	(677)
Total financial expenses	(17,514)	(3,631)	(3,813)
Total	$ (12,046)	$ 8,340	$ 16,758

Information Concerning the Gr_8

Information Concerning the Group's Consolidated Operations - Disclosure of Income Tax (Expense or Income) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Major components of tax expense (income) [abstract]
Income (loss) before taxes from continuing operations	$ (97,483)	$ (115,212)	$ (88,333)
Theoretical group tax rate	24.88%	25.35%	23.66%
Theoretical tax benefit (expense)	$ 24,254	$ 29,208	$ 20,901
Permanent differences	(1,141)	(1,131)	832
Research tax credit	3,245	2,786	2,079
Share-based compensation & other IFRS adjustments	(4,198)	(7,828)	(8,065)
Non recognition of deferred tax assets related to tax losses and temporary differences	(22,159)	(23,079)	(15,652)
Other differences	0	43	(95)
Effective tax expense	$ 0	$ 0	$ 0
Effective tax rate	0.00%	0.00%	0.00%

Information Concerning the Gr_9

Information Concerning the Group's Consolidated Operations - Disclosure of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in deferred tax liability (asset) [abstract]
Credits and net operating loss carryforwards	$ 141,954	$ 102,112	$ 65,555
Pension commitments	1,003	714	569
Leases	319	47	(4)
Impairment of assets	1	1	10
Revenue recognition	(491)	197	200
Other	1,308	284	491
Total unrecognized deferred tax assets, net	$ (144,095)	$ (103,354)	$ (66,823)

Information Concerning the G_10

Information Concerning the Group's Consolidated Operations - Summary of Key Performance Indicators by Reportable Segments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of operating segments [line items]
External revenues	$ 73,949	$ 15,190	$ 12,731
External other income	8,507	7,800	8,701
External revenues and other income	82,456	22,990	21,432
Cost of revenue	(36,275)	(11,392)	(2,739)
Research and development expenses	(86,950)	(92,042)	(76,567)
Selling, general and administrative expenses	(44,201)	(43,017)	(47,248)
Other operating income and expenses	(466)	(91)	31
Total operating expenses	(167,893)	(146,542)	(126,523)
Operating income (loss) before tax	(85,437)	(123,552)	(105,091)
Financial gain (loss)	(12,046)	8,340	16,758
Net income (loss) from discontinued operations	(97,483)	(115,212)	(88,333)
Non controlling interests	(16,409)	(13,121)	(9,640)
Net income (loss) attributable to shareholders of Cellectis	(81,074)	(102,091)	(78,693)
Adjustment of share-based compensation attributable to shareholders of Cellectis	14,365	23,242	34,563
Adjusted net income (loss) attributable to shareholders of Cellectis	(66,709)	(78,849)	(44,130)
Depreciation and amortization	(9,819)	(6,875)	(2,377)
Additions to tangible and intangible assets	50,599	17,666	4,911
Research and Development [member]
Disclosure of operating segments [line items]
Adjustment of share-based compensation attributable to shareholders of Cellectis	7,591	11,629	17,689
Selling, General and Administration [member]
Disclosure of operating segments [line items]
Adjustment of share-based compensation attributable to shareholders of Cellectis	6,774	11,613	16,873
Plants [member]
Disclosure of operating segments [line items]
External revenues and other income	22,892	7,294	414
Cost of revenue	(34,324)	(9,275)	(595)
Research and development expenses	(9,903)	(12,390)	(8,638)
Selling, general and administrative expenses	(21,688)	(26,090)	(21,067)
Other operating income and expenses	(103)	25	(50)
Total operating expenses	(66,018)	(47,730)	(30,351)
Operating income (loss) before tax	(43,126)	(40,436)	(29,937)
Financial gain (loss)	(776)	294	1,420
Net income (loss) from discontinued operations	(43,902)	(40,142)	(28,517)
Non controlling interests	(16,409)	(13,121)	(9,640)
Net income (loss) attributable to shareholders of Cellectis	(27,493)	(27,021)	(18,877)
Adjustment of share-based compensation attributable to shareholders of Cellectis	4,337	8,292	6,056
Adjusted net income (loss) attributable to shareholders of Cellectis	(23,156)	(18,729)	(12,821)
Depreciation and amortization	(1,869)	(1,233)	(637)
Additions to tangible and intangible assets	1,786	2,998	1,871
Plants [member] | Research and Development [member]
Disclosure of operating segments [line items]
Adjustment of share-based compensation attributable to shareholders of Cellectis	801	1,619	838
Plants [member] | Selling, General and Administration [member]
Disclosure of operating segments [line items]
Adjustment of share-based compensation attributable to shareholders of Cellectis	3,536	6,673	5,218
Therapeutics [member]
Disclosure of operating segments [line items]
External revenues and other income	59,564	15,696	21,018
Cost of revenue	(1,951)	(2,117)	(2,144)
Research and development expenses	(77,048)	(79,652)	(67,929)
Selling, general and administrative expenses	(22,513)	(16,927)	(26,180)
Other operating income and expenses	(363)	(116)	81
Total operating expenses	(101,875)	(98,812)	(96,172)
Operating income (loss) before tax	(42,311)	(83,116)	(75,154)
Financial gain (loss)	(11,270)	8,045	15,339
Net income (loss) from discontinued operations	(53,581)	(75,071)	(59,816)
Non controlling interests	0	0	0
Net income (loss) attributable to shareholders of Cellectis	(53,581)	(75,071)	(59,816)
Adjustment of share-based compensation attributable to shareholders of Cellectis	10,028	14,950	28,507
Adjusted net income (loss) attributable to shareholders of Cellectis	(43,553)	(60,121)	(31,309)
Depreciation and amortization	(7,950)	(5,642)	(1,740)
Additions to tangible and intangible assets	48,813	14,668	3,040
Therapeutics [member] | Research and Development [member]
Disclosure of operating segments [line items]
Adjustment of share-based compensation attributable to shareholders of Cellectis	6,790	10,010	16,852
Therapeutics [member] | Selling, General and Administration [member]
Disclosure of operating segments [line items]
Adjustment of share-based compensation attributable to shareholders of Cellectis	3,238	4,940	11,655
Operating Segments [member]
Disclosure of operating segments [line items]
External revenues	73,949	15,190	12,731
Operating Segments [member] | Plants [member]
Disclosure of operating segments [line items]
External revenues	22,892	7,294	236
Operating Segments [member] | Therapeutics [member]
Disclosure of operating segments [line items]
External revenues	51,057	7,896	12,495
Inter-segment Revenues [member]
Disclosure of operating segments [line items]
External other income	8,507	7,800	8,701
Inter-segment Revenues [member] | Plants [member]
Disclosure of operating segments [line items]
External other income	0	0	178
Inter-segment Revenues [member] | Therapeutics [member]
Disclosure of operating segments [line items]
External other income	$ 8,507	$ 7,800	$ 8,523

Impairment Tests - Additional I

Impairment Tests - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of impairment loss and reversal of impairment loss [line items]
Impairment of assets	$ 0	$ 0	$ 0

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020
Computer Software [member] | Bottom of Range [member]
Disclosure of detailed information about intangible assets [line items]
Estimated useful lives	1 year
Computer Software [member] | Top of Range [member]
Disclosure of detailed information about intangible assets [line items]
Estimated useful lives	3 years
Patents [member] | Top of Range [member]
Disclosure of detailed information about intangible assets [line items]
Estimated useful lives	20 years

Intangible Assets - Details Inf

Intangible Assets - Details Information About Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of detailed information about intangible assets [line items]
Beginning balance	$ 1,108	$ 1,268	$ 1,431
Additions to intangible assets	517	82	117
Disposal of intangible assets	0	(50)	(7)
Reclassification	76	6	6
Depreciation expense	(206)	(174)	(217)
Translation adjustments	89	(24)	(61)
Ending balance	1,584	1,108	1,268
Gross value at end of period	4,004	3,125	3,146
Accumulated depreciation and impairment at end of period	(2,419)	(2,017)	(1,878)
Software and Patents [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	431	577	811
Additions to intangible assets	558	84	14
Disposal of intangible assets	0	(50)	(7)
Reclassification	76	6	6
Depreciation expense	(206)	(174)	(217)
Translation adjustments	30	(12)	(30)
Ending balance	889	431	577
Gross value at end of period	3,309	2,448	2,454
Accumulated depreciation and impairment at end of period	(2,419)	(2,017)	(1,878)
Assets Under Construction [member]
Disclosure of detailed information about intangible assets [line items]
Beginning balance	677	691	619
Additions to intangible assets	(41)	(2)	103
Disposal of intangible assets	0
Reclassification	0
Depreciation expense	0
Translation adjustments	59	(12)	(31)
Ending balance	695	677	691
Gross value at end of period	695	$ 677	$ 691
Accumulated depreciation and impairment at end of period	$ 0

Right-of-use Assets - Additiona

Right-of-use Assets - Additional Information (Detail) $ in Millions	Dec. 31, 2020USD ($)
Calyxt [Member]
Disclosure of quantitative information about right-of-use assets [line items]
Right of use assets adjusted to net deferred losses	$ 1.8

Right-of-use Assets - Details I

Right-of-use Assets - Details Information About Breakdown Of Right Of Use Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of quantitative information about right-of-use assets [line items]
Beginning balance	$ 45,612
Ending balance	73,845	$ 45,612
Right-of-use assets [member]
Disclosure of quantitative information about right-of-use assets [line items]
Beginning balance	45,612	37,569
Additions	33,088	12,873
Depreciation expense	(6,472)	(4,578)
Translation adjustments	1,617	(252)
Ending balance	73,845	45,612
Gross value at end of period	85,389	50,328
Accumulated depreciation at end of period	(11,544)	(4,716)
Building lease [member] | Right-of-use assets [member]
Disclosure of quantitative information about right-of-use assets [line items]
Beginning balance	43,112	36,061
Additions	24,719	11,357
Depreciation expense	(4,904)	(4,058)
Translation adjustments	1,699	(248)
Ending balance	64,626	43,112
Gross value at end of period	73,878	47,175
Accumulated depreciation at end of period	(9,252)	(4,063)
Office and laboratory equipment [member] | Right-of-use assets [member]
Disclosure of quantitative information about right-of-use assets [line items]
Beginning balance	2,500	1,508
Additions	8,369	1,516
Depreciation expense	(1,568)	(520)
Translation adjustments	(82)	(4)
Ending balance	9,219	2,500
Gross value at end of period	11,511	3,153
Accumulated depreciation at end of period	$ (2,292)	$ (653)

Property, Plant and Equipment -

Property, Plant and Equipment - Summary of Property Plant and Equipment Estimated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2020
Buildings and Other Outside Improvements [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	10-20 years
Leasehold Improvements [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	5-10 years
Office Furniture [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	10 years
Laboratory Equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	3-10 years
Office Equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	5 years
IT Equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives	3 years

Property, Plant and Equipment_2

Property, Plant and Equipment - Disclosure of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	$ 23,712	$ 10,041	$ 7,226
Additions to tangible assets	50,082	17,584	6,263
Disposal of tangible assets	(118)	(430)	(1,164)
Reclassification	(76)	(5)	(6)
Depreciation expense	(3,141)	(2,123)	(2,091)
Translation adjustments	1,215	(46)	(188)
Ending balance	71,673	23,712	10,041
Gross value at end of period	93,043	41,529	26,160
Accumulated depreciation and impairment at end of period	(21,370)	(17,817)	(16,119)
IFRS 16 [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		8,732
Ending balance			8,732
Land and Buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	3,330	3,229	3,159
Additions to tangible assets	5,248	318	879
Disposal of tangible assets	4
Reclassification	8,258	15	39
Depreciation expense	(817)	(192)	(758)
Translation adjustments	742	(40)	(90)
Ending balance	16,765	3,330	3,229
Gross value at end of period	22,518	7,833	7,604
Accumulated depreciation and impairment at end of period	(5,752)	(4,503)	(4,375)
Land and Buildings [member] | IFRS 16 [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		3,229
Ending balance			3,229
Technical Equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	3,160	3,393	2,505
Additions to tangible assets	2,034	374	1,622
Disposal of tangible assets	(122)	(10)	(49)
Reclassification	692	1,974	216
Depreciation expense	(1,464)	(1,247)	(854)
Translation adjustments	136	(15)	(46)
Ending balance	4,436	3,160	3,393
Gross value at end of period	17,381	13,962	13,297
Accumulated depreciation and impairment at end of period	(12,946)	(10,802)	(9,903)
Technical Equipment [member] | IFRS 16 [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		2,084
Ending balance			2,084
Fixtures, Fittings and Other Equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	2,435	2,172	753
Additions to tangible assets	854	329	1,820
Disposal of tangible assets	0	(1)	(690)
Reclassification	670	630	793
Depreciation expense	(861)	(684)	(478)
Translation adjustments	73	(11)	(27)
Ending balance	3,171	2,435	2,172
Gross value at end of period	5,843	4,149	3,215
Accumulated depreciation and impairment at end of period	(2,672)	(1,714)	(1,043)
Fixtures, Fittings and Other Equipment [member] | IFRS 16 [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		2,172
Ending balance			2,172
Assets Under Construction [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance	14,787	1,247	809
Additions to tangible assets	41,946	16,563	1,942
Disposal of tangible assets	0	(419)	(426)
Reclassification	(9,696)	(2,624)	(1,053)
Depreciation expense	0
Translation adjustments	264	20	(25)
Ending balance	47,301	14,787	1,247
Gross value at end of period	47,301	15,585	2,045
Accumulated depreciation and impairment at end of period	$ 0	(798)	(798)
Assets Under Construction [member] | IFRS 16 [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning balance		$ 1,247
Ending balance			$ 1,247

Property, Plant and Equipment_3

Property, Plant and Equipment - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2020EUR (€)
Disclosure of detailed information about property, plant and equipment [line items]
Assets pledged as security for financial liabilities | €					€ 0
Additions to tangible assets	$ 50,082	$ 17,584	$ 6,263
IAS 17 [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Net deferred losses recognised				$ 1,800
Assets Put In Service [member]
Disclosure of detailed information about property, plant and equipment [line items]
Additions to tangible assets others	6,600
Assets Put In Service [member] | Paris [member]
Disclosure of detailed information about property, plant and equipment [line items]
Additions to tangible assets	2,300
Assets Put In Service [member] | North Carolina [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Additions to tangible assets	37,900
Assets Put In Service [member] | Raleigh [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Additions to tangible assets	600
Technical Equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Additions to tangible assets	2,034	$ 374	$ 1,622
Calyxt Inc and Cellectis Sites [member]
Disclosure of detailed information about property, plant and equipment [line items]
Additions to tangible assets	5,200
Other equipment	2,900
Calyxt Inc and Cellectis Sites [member] | Technical Equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Additions to tangible assets	2,000
Calyxt Inc and Cellectis Sites [member] | Other property, plant and equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Additions to tangible assets	900
Calyxt Inc. [member]
Disclosure of detailed information about property, plant and equipment [line items]
Net book value of assets sold				$ 9,200
Cellectis [member] | Assets Put In Service [member]
Disclosure of detailed information about property, plant and equipment [line items]
Additions to tangible assets	3,500
Cellectis [member] | Assets Put In Service [member] | Paris [member]
Disclosure of detailed information about property, plant and equipment [line items]
Additions to tangible assets	$ 5,500

Financial Assets and Liabilit_3

Financial Assets and Liabilities - Summary of Financial Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Disclosure of financial assets and liabilities [line items]
Accounting category fair value through profit and loss	$ 241,148	$ 340,522
Accounting category amortized cost	49,972	38,001
Book value on the statement of financial position	291,120	378,523
Fair value	291,120	378,523
Accounting category fair value through profit and loss	0
Accounting category amortized cost	155,032	85,368
Book value on the statement of financial position	155,032	85,368
Fair value	155,032	85,368
Non-Current Financial Assets [member]
Disclosure of financial assets and liabilities [line items]
Accounting category fair value through profit and loss	0
Accounting category amortized cost	7,007	5,517
Book value on the statement of financial position	7,007	5,517
Fair value	7,007	5,517
Trade Receivables [member]
Disclosure of financial assets and liabilities [line items]
Accounting category fair value through profit and loss	0
Accounting category amortized cost	5,171	2,959
Book value on the statement of financial position	5,171	2,959
Fair value	5,171	2,959
Subsidies Receivables [member]
Disclosure of financial assets and liabilities [line items]
Accounting category fair value through profit and loss	0
Accounting category amortized cost	10,703	9,140
Book value on the statement of financial position	10,703	9,140
Fair value	10,703	9,140
Current Financial Assets [member]
Disclosure of financial assets and liabilities [line items]
Accounting category fair value through profit and loss	0
Accounting category amortized cost	27,091	20,385
Book value on the statement of financial position	27,091	20,385
Fair value	27,091	20,385
Cash and Cash Equivalents [member]
Disclosure of financial assets and liabilities [line items]
Accounting category fair value through profit and loss	241,148	340,522
Accounting category amortized cost	0
Book value on the statement of financial position	241,148	340,522
Fair value	241,148	340,522
Non current lease debts [Member]
Disclosure of financial assets and liabilities [line items]
Accounting category amortized cost	75,764
Book value on the statement of financial position	75,764
Fair value	75,764
Other non current financial liabilities [member]
Disclosure of financial assets and liabilities [line items]
Accounting category amortized cost	28,836
Book value on the statement of financial position	28,836
Fair value	28,836
Current lease debts [member]
Disclosure of financial assets and liabilities [line items]
Accounting category amortized cost	6,696
Book value on the statement of financial position	6,696
Fair value	6,696
Non-Current Financial Liabilities [member]
Disclosure of financial assets and liabilities [line items]
Accounting category fair value through profit and loss
Accounting category amortized cost		46,540
Book value on the statement of financial position		46,540
Fair value		46,540
Lease debts [member]
Disclosure of financial assets and liabilities [line items]
Accounting category amortized cost		1,067
Book value on the statement of financial position		1,067
Fair value		1,067
Trade Payables [member]
Disclosure of financial assets and liabilities [line items]
Accounting category fair value through profit and loss	0
Accounting category amortized cost	24,609	29,264
Book value on the statement of financial position	24,609	29,264
Fair value	24,609	29,264
Other Current Liabilities1 [member]
Disclosure of financial assets and liabilities [line items]
Accounting category fair value through profit and loss	0
Accounting category amortized cost	19,127	8,497
Book value on the statement of financial position	19,127	8,497
Fair value	$ 19,127	$ 8,497

Financial Assets and Liabilit_4

Financial Assets and Liabilities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of financial assets and liabilities [line items]
Derivative financial assets	$ 0
Finance lease liabilities	82,460,000
Cash and cash equivalents	241,148,000	$ 340,522,000	$ 451,501,000	$ 256,380,000
Financial liability	155,032,000	$ 85,368,000
Loan received from bank	22,701,000
NEW YORK
Disclosure of financial assets and liabilities [line items]
Borrowings	1,500,000
Raleigh Good Manufacturing Practices [Member] | Equipment Rental Agreement [Member]
Disclosure of financial assets and liabilities [line items]
Financial liability	3,000,000
Paycheck Protection Program Loan [Member]
Disclosure of financial assets and liabilities [line items]
Borrowings	1,500,000
Paycheck Protection Program Loan [Member] | Calyxt Inc [member]
Disclosure of financial assets and liabilities [line items]
Borrowings	1,500,000
State Guaranteed Loan [Member]
Disclosure of financial assets and liabilities [line items]
Loan received from bank	$ 22,800,000
US Dollar [member] | Cash Cash and Cash Equivalents and Current Assets [member]
Disclosure of financial assets and liabilities [line items]
Currency denominated percentage	56.00%	63.00%

Inventories - Additional Inform

Inventories - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of inventories [line items]
Inventories	$ 1,606	$ 2,897
Grain And Seeds [Member] | Calyxt Inc [Member]
Disclosure of inventories [line items]
Inventories	1,400	2,600
Provision for impairment	3,900	0
Laboratory Equipment [member]
Disclosure of inventories [line items]
Inventories	$ 200	$ 300

Trade Receivables and Other C_3

Trade Receivables and Other Current Assets - Disclosure of Trade Receivables (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Trade and other receivables [abstract]
Trade receivables	$ 5,787	$ 3,513
Valuation allowance	(616)	(554)
Total net value of trade receivables	$ 5,171	$ 2,959

Trade Receivables and Other C_4

Trade Receivables and Other Current Assets - Disclosure of Subsidies Receivables (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Receivables1 [abstract]
Research tax credit	$ 10,703	$ 9,140
Total subsidies receivables	$ 10,703	$ 9,140

Trade Receivables and Other C_5

Trade Receivables and Other Current Assets - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Prepaid expenses and other current assets [line items]
Deferred expenses and other current assets payments to suppliers	$ 2.7
Deferred expenses and other current assets right to obtain equipment	3
Cellectis [member]
Prepaid expenses and other current assets [line items]
Deferred expenses and other current assets employee stock option receivables	6.2
France [member]
Prepaid expenses and other current assets [line items]
Research tax credit receivables	9.2	$ 7.9
France [member] | Previously stated [member]
Prepaid expenses and other current assets [line items]
Research tax credit receivables	$ 1.3	$ 1.2

Trade Receivables and Other C_6

Trade Receivables and Other Current Assets - Disclosure of Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other Current Assets [abstract]
VAT receivables	$ 3,093	$ 3,044
Prepaid expenses and other prepayments	14,113	11,829
Tax and social receivables	227	150
Deferred expenses and other current assets	12,210	594
Total other current assets	$ 29,643	$ 15,617

Current Financial Assets and _3

Current Financial Assets and Cash and Cash Equivalents - Summary of Current Financial Assets and Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of current financial assets and cash and cash equivalents [line items]
Current financial assets	$ 27,091	$ 20,385
Cash and cash equivalents	241,148	340,522	$ 451,501	$ 256,380
Carrying Value [member]
Disclosure of current financial assets and cash and cash equivalents [line items]
Current financial assets	27,091	20,385
Cash and cash equivalents	241,148	340,522
Current financial assets and cash and cash equivalents	268,239	360,907
Estimated Fair Value [member]
Disclosure of current financial assets and cash and cash equivalents [line items]
Current financial assets	27,091	20,385
Cash and cash equivalents	241,148	340,522
Current financial assets and cash and cash equivalents	$ 268,239	$ 360,907

Current Financial Assets and _4

Current Financial Assets and Cash and Cash Equivalents - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Disclosure of current financial assets and cash and cash equivalents [line items]
Restricted cash	$ 15.4
Other current financial assets	11.7
Furniture and equipment sales lease back [member]
Disclosure of current financial assets and cash and cash equivalents [line items]
Restricted cash	1	$ 1.4
Short term restricted cash	0.4	0.4
Manufacturing Facility [Member]
Disclosure of current financial assets and cash and cash equivalents [line items]
Restricted cash	$ 15
Short term restricted cash		$ 20

Current Financial Assets and _5

Current Financial Assets and Cash and Cash Equivalents - Summary of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash and cash equivalents [abstract]
Cash and bank accounts	$ 164,586	$ 270,630
Money market funds	13,977	13,722
Fixed bank deposits	62,585	56,170
Total cash and cash equivalents	$ 241,148	$ 340,522	$ 451,501	$ 256,380

Financial Liabilities - Schedul

Financial Liabilities - Schedule of Financial Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Categories of financial liabilities [abstract]
Lease debts	$ 75,764	$ 46,540
State Guaranteed loan « PGE »	22,701
PPP loan	1,518
Other non-current financial liabilities	4,617
Total non-current financial liabilities	104,600	46,540
Lease debts	6,696	1,067
Total current financial liabilities	6,696	1,067
Trade payables	24,609	29,264
Other current liabilities	19,127	8,497
Total Financial liabilities	$ 155,032	$ 85,368

Financial Liabilities - Sched_2

Financial Liabilities - Schedule Representing Due Dates of the Financial Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Disclosure of offsetting of financial liabilities [line items]
Lease debts	$ 82,460
Other financial liabilities	28,836
Financial liabilities	111,296
Trade payables	24,609	$ 29,264
Other current liabilities	19,127	8,497
Total Financial liabilities	155,032	$ 85,368
Less than One Year [member]
Disclosure of offsetting of financial liabilities [line items]
Lease debts	6,696
Other financial liabilities	78
Financial liabilities	6,774
Trade payables	24,609
Other current liabilities	19,127
Total Financial liabilities	50,510
One to Five Years [member]
Disclosure of offsetting of financial liabilities [line items]
Lease debts	30,706
Other financial liabilities	24,698
Financial liabilities	55,404
Total Financial liabilities	54,404
More than Five Years [member]
Disclosure of offsetting of financial liabilities [line items]
Lease debts	45,058
Other financial liabilities	4,061
Financial liabilities	49,118
Total Financial liabilities	$ 49,118

Financial liabilities - Additio

Financial liabilities - Additional Information (Detail) $ in Thousands, € in Millions	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)	Dec. 31, 2019USD ($)
Disclosure of offsetting of financial liabilities [line items]
Financial liability	$ 155,032		$ 85,368
Secured Borrowings	22,701
New York [Member]
Disclosure of offsetting of financial liabilities [line items]
Borrowings	1,500
Raleigh [Member]
Disclosure of offsetting of financial liabilities [line items]
Financial liabilities tenant improvement allowance	3,300
Paycheck Protection Program Loan [Member]
Disclosure of offsetting of financial liabilities [line items]
Borrowings	1,500
State Guaranteed Loan [Member]
Disclosure of offsetting of financial liabilities [line items]
Secured Borrowings	22,800
State Guaranteed Loan [Member] | Major Borrowing Transactions [Member]
Disclosure of offsetting of financial liabilities [line items]
Secured Borrowings	$ 22,700	€ 18.5
Guaranteed borrowing amount, percentage	90.00%
State Guaranteed Loan [Member] | Major Borrowing Transactions [Member] | Bottom of range [member]
Disclosure of offsetting of financial liabilities [line items]
Fixed interest rate	0.25%	0.25%
State Guaranteed Loan [Member] | Major Borrowing Transactions [Member] | Top of range [member]
Disclosure of offsetting of financial liabilities [line items]
Fixed interest rate	2.35%	2.35%
Equipment Rental Agreement [Member] | Raleigh Good Manufacturing Practices [Member]
Disclosure of offsetting of financial liabilities [line items]
Financial liability	$ 3,000

Other Current Liabilities - Sum

Other Current Liabilities - Summary of Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Miscellaneous current liabilities [abstract]
VAT Payables	$ 81	$ 130
Accruals for personnel related expenses	13,235	7,295
Other	6,077	1,072
Total	$ 19,127	$ 8,497

Other Current Liabilities - Add

Other Current Liabilities - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Other current liabilities [abstract]
Board of directors attendance fee	$ 0.3	$ 0.3
Tax liabilities	0.2	0.2
Accrued liabilitites current for fixed assets	$ 3.7	$ 0.6

Deferred Revenues and Contrac_3

Deferred Revenues and Contract Liabilities - Summary of Deferred Revenues and Contract Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accruals and deferred income [abstract]
Deferred revenues and contract liabilities	$ 452	$ 20,033
Others
Total Deferred revenue and contract liabilities	$ 452	$ 20,033

Deferred Revenues and Contrac_4

Deferred Revenues and Contract Liabilities - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 04, 2020	Dec. 31, 2020	Dec. 31, 2018
Recognition of previously deferred upfront payments	$ 19,400	$ 20,291	$ 7,114
Development And Commercial Milestones [Member]
Recognition of previously deferred upfront payments		16,900
Potential milestones to receive		$ 2,500

Capital - Schedule of Classes o

Capital - Schedule of Classes of Share Capital (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of classes of share capital [line items]
Beginning balance	$ 355,470	$ 450,272	$ 283,986
Balance at beginning of year	42,465,669	42,430,069	35,960,062
Capital increase by issuance of common shares		35,600	6,146,000
Exercise of share warrants, employee warrants and stock options	314,517		324,007
Other movements			$ (40)
Balance at end of year	$ 308,846	$ 355,470	$ 450,272
Balance at end of year	42,780,186	42,465,669	42,430,069
Nominal value	$ 0.05	$ 0.05	$ 0.05
Premiums Related to Share Capital [member]
Disclosure of classes of share capital [line items]
Beginning balance	$ 843,478	$ 828,525	$ 614,037
Capital Increase			178,230
Exercise of share warrants, employee warrants and stock options	6,101		7,751
Non-cash stock based compensation expense	14,365	14,951	28,507
Other movements	(32)	2
Balance at end of year	863,912	843,478	828,525
Share Capital Ordinary Shares [member]
Disclosure of classes of share capital [line items]
Beginning balance	2,767	2,765	2,367
Capital Increase		2	379
Exercise of share warrants, employee warrants and stock options	18		19
Balance at end of year	$ 2,785	$ 2,767	$ 2,765

Capital - Additional Informatio

Capital - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Oct. 20, 2020	May 22, 2018	Jul. 25, 2017	Oct. 28, 2014	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Oct. 28, 2011
Capital structure [line items]
Exercise stock option		$ 57,000	$ 64,400
Voting right description					At December 31, 2020, we had 42,780,186 ordinary shares outstanding of which 6,067,389 had a double voting right.	At December 31, 2019, we had 42,465,669 ordinary shares outstanding of which 4,389,581 had a double voting right.	At December 31, 2018, we had 42,430,069 ordinary shares outstanding of which 5,016,911 had a double voting right.
Number of shares ordinary outstanding					42,780,186	42,465,669	42,430,069	35,960,062
Number of shares ordinary having double voting right					6,067,389	4,389,581	5,016,911
Par value per share					$ 0.05	$ 0.05	$ 0.05
Shares to underwriters			$ 20,000
Equity value					$ 275,573	$ 315,123
BSA [member]
Capital structure [line items]
Ordinary shares issued				1,470,836					12,195,113
Number of employee warrants exercisable					19,702
Hold Two Years [member]
Capital structure [line items]
Voting right description					After a shareholder continuously holds ordinary shares for two years, each ordinary share held by such shareholder is entitled to two votes.
Calyxt Inc [member]
Capital structure [line items]
Ordinary shares issued	3,750,000	4,057,500	8,050,000
Exercise stock option	$ 15,000	$ 57,000	$ 64,400
Underwriting discounts and commissions		$ 3,200
Par value per share	$ 4	$ 15	$ 8
Shares to underwriters			$ 20,000
Non-controlling shareholders interest					35.30%	31.10%
Offering expense		$ 700
Cellectis [member] | Calyxt Inc [member]
Capital structure [line items]
Purchase of common stock		550,000
Purchase of common shares	1,250,000
Equity value	$ 5,000
Purchase of common stock, value	14,000
BSA [member]
Capital structure [line items]
Exercise stock option				$ 16,400
Calyxt Inc. [member]
Capital structure [line items]
Ordinary shares issued		4,057,500	8,050,000
Exercise stock option		$ 57,000
Equity interests					2.70%	6.10%	3.10%
Compensation expense					$ 6,700	$ 4,400	$ 3,300
Calyxt Inc. [member] | Calyxt Inc [member]
Capital structure [line items]
Exercise stock option	$ 15,000
Calyxt Inc. [member] | Cellectis [member]
Capital structure [line items]
Purchase of common stock		550,000
Purchase of common stock, value		$ 8,300
Capital evolution 2018 [member]
Capital structure [line items]
Options exercise							322,068
Exercise stock option							$ 230,629
Underwriting discounts and commissions							$ 178,611,687
Capital evolution 2018 [member] | BSA [member]
Capital structure [line items]
Ordinary shares issued							6,146,000
Number of employee warrants exercisable							1,867
Exercise stock option							$ 14,112
Number of non-employee warrants subscribed							160,000
Capital evolution 2020 [member]
Capital structure [line items]
Ordinary shares issued					20,464
Exercise stock option					$ 163,134
Capital evolution 2020 [member] | BSA [member]
Capital structure [line items]
Number of employee warrants exercisable					291,053
Exercise stock option					$ 5,197,970
BSPCE [member]
Capital structure [line items]
Exercise stock option							$ 7,525,542
Free Shares [member] | Capital evolution 2018 [member]
Capital structure [line items]
Ordinary shares issued							1,939
Free Shares [member] | Capital evolution 2019 [member] | BSA [member]
Capital structure [line items]
Number of shares converted						35,600
Free Shares [member] | Capital evolution 2019 [member] | BSA [member]
Capital structure [line items]
Number of shares converted						35,600
Free Shares [member] | Capital evolution 2020 [member]
Capital structure [line items]
Ordinary shares issued					291,053
Number of shares converted					3,000
Free Shares [member] | Capital evolution 2020 [member] | BSA [member]
Capital structure [line items]
Number of shares converted					3,000

Capital - Disclosure of Share W

Capital - Disclosure of Share Warrants and Non-employee Warrants (Detail)	12 Months Ended
	Dec. 31, 2020shares€ / shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of warrants/shares oustanding as of 01/01/2020	10,658,309
Number of warrants/shares granted	1,070,685
Number of warrants/shares vested/exercised	313,755
Number of warrants/shares voided	399,707
Number of warrants/shares oustanding as of 12/31/2020	11,015,532
Maximum of shares to be issued	11,015,532
Number of warrants/shares exercisable12/31/2020	8,901,623
Free Shares [member] | 10/08/2018 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	10/08/2018
Type	Free shares
Number of warrants/shares oustanding as of 01/01/2020	3,000
Number of warrants/shares vested/exercised	3,000
Strike price per share in euros | € / shares	€ 23.84
Free Shares [member] | 12/17/2018 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	12/17/2018
Type	Free shares
Number of warrants/shares oustanding as of 01/01/2020	13,000
Number of warrants/shares voided	13,000
Strike price per share in euros | € / shares	€ 16
Free Shares [member] | 03/07/2019 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	03/07/2019
Type	Free shares
Number of warrants/shares oustanding as of 01/01/2020	2,500
Number of warrants/shares oustanding as of 12/31/2020	2,500
Maximum of shares to be issued	2,500
Strike price per share in euros | € / shares	€ 16
Free Shares [member] | 04/24/2019 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	04/24/2019
Type	Free shares
Number of warrants/shares oustanding as of 01/01/2020	6,500
Number of warrants/shares oustanding as of 12/31/2020	6,500
Maximum of shares to be issued	6,500
Strike price per share in euros | € / shares	€ 18.01
Free Shares [member] | 07/16/2019 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	07/16/2019
Type	Free shares
Number of warrants/shares oustanding as of 01/01/2020	4,000
Number of warrants/shares oustanding as of 12/31/2020	4,000
Maximum of shares to be issued	4,000
Strike price per share in euros | € / shares	€ 14.01
Free Shares [member] | 11/06/2019 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	11/06/2019
Type	Free shares
Number of warrants/shares oustanding as of 01/01/2020	21,500
Number of warrants/shares voided	6,500
Number of warrants/shares oustanding as of 12/31/2020	15,000
Maximum of shares to be issued	15,000
Strike price per share in euros | € / shares	€ 11.32
Free Shares [member] | 11/18/2019 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	11/18/2019
Type	Free shares
Number of warrants/shares oustanding as of 01/01/2020	16,500
Number of warrants/shares oustanding as of 12/31/2020	16,500
Maximum of shares to be issued	16,500
Strike price per share in euros | € / shares	€ 12.16
Free Shares [member] | 03/4/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	03/04/2020
Type	Free shares
Number of warrants/shares granted	6,500
Number of warrants/shares oustanding as of 12/31/2020	6,500
Maximum of shares to be issued	6,500
Strike price per share in euros | € / shares	€ 14.54
Free Shares [member] | 04/14/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	04/14/2020
Type	Free shares
Number of warrants/shares granted	20,000
Number of warrants/shares oustanding as of 12/31/2020	20,000
Maximum of shares to be issued	20,000
Strike price per share in euros | € / shares	€ 9.14
Free Shares [member] | 06/19/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	06/19/2020
Type	Free shares
Number of warrants/shares granted	16,500
Number of warrants/shares oustanding as of 12/31/2020	16,500
Maximum of shares to be issued	16,500
Strike price per share in euros | € / shares	€ 14.76
Free Shares [member] | 07/20/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	07/20/2020
Type	Free shares
Number of warrants/shares granted	10,000
Number of warrants/shares oustanding as of 12/31/2020	10,000
Maximum of shares to be issued	10,000
Strike price per share in euros | € / shares	€ 15.76
Free Shares [member] | 08/05/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	08/05/2020
Type	Free shares
Number of warrants/shares granted	70,000
Number of warrants/shares oustanding as of 12/31/2020	70,000
Maximum of shares to be issued	70,000
Strike price per share in euros | € / shares	€ 14
Free Shares [member] | 09/11/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	09/11/2020
Type	Free shares
Number of warrants/shares granted	15,000
Number of warrants/shares oustanding as of 12/31/2020	15,000
Maximum of shares to be issued	15,000
Strike price per share in euros | € / shares	€ 14.58
Free Shares [member] | 10/14/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	10/14/2020
Type	Free shares
Number of warrants/shares granted	423,285
Number of warrants/shares voided	6,535
Number of warrants/shares oustanding as of 12/31/2020	416,750
Maximum of shares to be issued	416,750
Strike price per share in euros | € / shares	€ 22.45
Free Shares [member] | 11/05/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	11/05/2020
Type	Free shares
Number of warrants/shares granted	16,600
Number of warrants/shares oustanding as of 12/31/2020	16,600
Maximum of shares to be issued	16,600
Strike price per share in euros | € / shares	€ 14.76
Free Shares [member] | 12/16/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	12/16/2020
Type	Free shares
Number of warrants/shares granted	7,300
Number of warrants/shares oustanding as of 12/31/2020	7,300
Maximum of shares to be issued	7,300
Strike price per share in euros | € / shares	€ 23.75
BSA [member] | 3/27/2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	03/27/2015
Type	BSA
Number of warrants/shares oustanding as of 01/01/2020	130,000
Number of warrants/shares oustanding as of 12/31/2020	130,000
Maximum of shares to be issued	130,000
Number of warrants/shares exercisable12/31/2020	130,000
Strike price per share in euros | € / shares	€ 38.45
BSA [member] | 5/18/2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	05/18/2015
Type	BSA
Number of warrants/shares oustanding as of 01/01/2020	50,000
Number of warrants/shares oustanding as of 12/31/2020	50,000
Maximum of shares to be issued	50,000
Number of warrants/shares exercisable12/31/2020	50,000
Strike price per share in euros | € / shares	€ 29.58
BSA [member] | 9/8/2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	09/08/2015
Type	BSA
Number of warrants/shares oustanding as of 01/01/2020	224,200
Number of warrants/shares oustanding as of 12/31/2020	224,200
Maximum of shares to be issued	224,200
Number of warrants/shares exercisable12/31/2020	224,200
Strike price per share in euros | € / shares	€ 28.01
BSA [member] | 3/14/2016 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	03/14/2016
Type	BSA
Number of warrants/shares oustanding as of 01/01/2020	147,025
Number of warrants/shares oustanding as of 12/31/2020	147,025
Maximum of shares to be issued	147,025
Number of warrants/shares exercisable12/31/2020	147,025
Strike price per share in euros | € / shares	€ 27.37
BSA [member] | 10/28/2016 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	10/28/2016
Type	BSA
Number of warrants/shares oustanding as of 01/01/2020	148,000
Number of warrants/shares oustanding as of 12/31/2020	148,000
Maximum of shares to be issued	148,000
Number of warrants/shares exercisable12/31/2020	148,000
Strike price per share in euros | € / shares	€ 18.68
BSA [member] | 10/11/2017 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	10/11/2017
Type	BSA
Number of warrants/shares oustanding as of 01/01/2020	200,000
Number of warrants/shares oustanding as of 12/31/2020	200,000
Maximum of shares to be issued	200,000
Number of warrants/shares exercisable12/31/2020	200,000
Strike price per share in euros | € / shares	€ 24.34
Stock options [member] | 3/24/2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	03/24/2015
Type	Stock Options
Number of warrants/shares oustanding as of 01/01/2020	1,612,994
Number of warrants/shares voided	21,391
Number of warrants/shares oustanding as of 12/31/2020	1,591,603
Maximum of shares to be issued	1,591,603
Number of warrants/shares exercisable12/31/2020	1,591,603
Strike price per share in euros | € / shares	€ 38.45
Stock options [member] | 9/8/2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	09/08/2015
Type	Stock Options
Number of warrants/shares oustanding as of 01/01/2020	1,623,200
Number of warrants/shares voided	24,500
Number of warrants/shares oustanding as of 12/31/2020	1,598,700
Maximum of shares to be issued	1,598,700
Number of warrants/shares exercisable12/31/2020	1,598,700
Strike price per share in euros | € / shares	€ 27.55
Stock options [member] | 3/14/2016 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	03/14/2016
Type	Stock Options
Number of warrants/shares oustanding as of 01/01/2020	1,652,595
Number of warrants/shares vested/exercised	2,354
Number of warrants/shares voided	13,536
Number of warrants/shares oustanding as of 12/31/2020	1,636,705
Maximum of shares to be issued	1,636,705
Number of warrants/shares exercisable12/31/2020	1,636,705
Strike price per share in euros | € / shares	€ 22.44
Stock options [member] | 10/28/2016 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	10/28/2016
Type	Stock Options
Number of warrants/shares oustanding as of 01/01/2020	2,178,893
Number of warrants/shares vested/exercised	238,660
Number of warrants/shares voided	21,599
Number of warrants/shares oustanding as of 12/31/2020	1,918,634
Maximum of shares to be issued	1,918,634
Number of warrants/shares exercisable12/31/2020	1,918,634
Strike price per share in euros | € / shares	€ 17.90
Stock options [member] | 10/11/2017 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	10/11/2017
Type	Stock Options
Number of warrants/shares oustanding as of 01/01/2020	960,000
Number of warrants/shares vested/exercised	1,000
Number of warrants/shares voided	35,000
Number of warrants/shares oustanding as of 12/31/2020	924,000
Maximum of shares to be issued	924,000
Number of warrants/shares exercisable12/31/2020	707,722
Strike price per share in euros | € / shares	€ 22.57
Stock options [member] | 10/08/2018 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	10/08/2018
Type	Stock Options
Number of warrants/shares oustanding as of 01/01/2020	50,000
Number of warrants/shares voided	30,000
Number of warrants/shares oustanding as of 12/31/2020	20,000
Maximum of shares to be issued	20,000
Number of warrants/shares exercisable12/31/2020	9,996
Strike price per share in euros | € / shares	€ 24.80
Stock options [member] | 12/17/2018 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	12/17/2018
Type	Stock Options
Number of warrants/shares oustanding as of 01/01/2020	40,000
Number of warrants/shares voided	40,000
Strike price per share in euros | € / shares	€ 18.37
Stock options [member] | 04/24/2019 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	04/24/2019
Type	Stock Options
Number of warrants/shares oustanding as of 01/01/2020	1,469,700
Number of warrants/shares vested/exercised	41,539
Number of warrants/shares voided	162,646
Number of warrants/shares oustanding as of 12/31/2020	1,265,515
Maximum of shares to be issued	1,265,515
Number of warrants/shares exercisable12/31/2020	531,538
Strike price per share in euros | € / shares	€ 18.25
Stock options [member] | 11/06/2019 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	11/06/2019
Type	Stock Options
Number of warrants/shares oustanding as of 01/01/2020	55,000
Number of warrants/shares voided	25,000
Number of warrants/shares oustanding as of 12/31/2020	30,000
Maximum of shares to be issued	30,000
Number of warrants/shares exercisable12/31/2020	7,500
Strike price per share in euros | € / shares	€ 11.06
Stock options [member] | 11/18/2019 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	11/18/2019
Type	Stock Options
Number of warrants/shares oustanding as of 01/01/2020	30,000
Number of warrants/shares vested/exercised	7,500
Number of warrants/shares oustanding as of 12/31/2020	22,500
Maximum of shares to be issued	22,500
Strike price per share in euros | € / shares	€ 12.33
Stock options [member] | 04/14/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	04/14/2020
Type	Stock Options
Number of warrants/shares granted	160,000
Number of warrants/shares oustanding as of 12/31/2020	160,000
Maximum of shares to be issued	160,000
Strike price per share in euros | € / shares	€ 8.27
Stock options [member] | 06/19/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	06/19/2020
Type	Stock Options
Number of warrants/shares oustanding as of 01/01/2020	17,000
Number of warrants/shares granted	17,000
Maximum of shares to be issued	17,000
Strike price per share in euros | € / shares	€ 15.84
Stock options [member] | 07/20/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	07/20/2020
Type	Stock Options
Number of warrants/shares granted	17,000
Number of warrants/shares oustanding as of 12/31/2020	17,000
Maximum of shares to be issued	17,000
Strike price per share in euros | € / shares	€ 15.12
Stock options [member] | 08/05/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	08/05/2020
Type	Stock Options
Number of warrants/shares granted	212,000
Number of warrants/shares oustanding as of 12/31/2020	212,000
Maximum of shares to be issued	212,000
Strike price per share in euros | € / shares	€ 14.62
Stock options [member] | 09/11/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	09/11/2020
Type	Stock Options
Number of warrants/shares granted	45,000
Number of warrants/shares oustanding as of 12/31/2020	45,000
Maximum of shares to be issued	45,000
Strike price per share in euros | € / shares	€ 14.36
Stock options [member] | 11/05/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	11/05/2020
Type	Stock Options
Number of warrants/shares granted	28,000
Number of warrants/shares oustanding as of 12/31/2020	28,000
Maximum of shares to be issued	28,000
Strike price per share in euros | € / shares	€ 14.62
BSPCE [member] | 7/27/2010 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	07/27/2010
Type	BSPCE
Number of warrants/shares oustanding as of 01/01/2020	19,702
Number of warrants/shares vested/exercised	19,702
Strike price per share in euros | € / shares	€ 7.97
Free Shares [member] | 09/11/2020 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Date	09/11/2020
Type	Free shares
Number of warrants/shares granted	6,500
Number of warrants/shares oustanding as of 12/31/2020	6,500
Maximum of shares to be issued	6,500
Strike price per share in euros | € / shares	€ 14.98

Capital - Schedule of Informati

Capital - Schedule of Information Relating to Subsidiaries that Reported Non-Controlling Interest (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of non-controlling interests [line items]
Revenue	$ 73,949	$ 15,190	$ 12,731
Net Profit (Loss)	(97,483)	(115,212)	(88,333)
Net Profit (Loss) attributable to NCI	(16,409)	(13,121)	(9,640)
Other comprehensive income	18,589	(6,000)	(19,122)
Total comprehensive income	(78,894)	(121,212)	(107,455)
Total comprehensive income attributable to NCI	(15,942)	(12,856)	$ (10,330)
Current assets	315,362	391,520
Non-current assets	154,109	75,949
Current liabilities	52,015	62,604
Non-current liabilities	108,610	49,395
Calyxt Inc. [member]
Disclosure of non-controlling interests [line items]
Revenue	22,892	7,294
Net Profit (Loss)	(43,902)	(40,142)
Net Profit (Loss) attributable to NCI	(16,409)	(13,121)
Other comprehensive income	(1,196)	(1,237)
Total comprehensive income	(45,098)	(41,378)
Total comprehensive income attributable to NCI	(15,942)	(12,856)
Current assets	39,590	63,528
Non-current assets	23,737	22,518
Current liabilities	6,945	6,642
Non-current liabilities	19,507	15,121
Net assets	36,875	64,283
Net assets attributable to NCI	$ 13,035	$ 19,973

Share-based Payments - Addition

Share-based Payments - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)shares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expected dividend yield			0.00%
Vesting period, years	4 years
Stock option expire, years	10 years
Share based arrangement number of other equity instruments granted | shares	1,070,685
Calyxt Inc. [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based compensation expense	$ 6.7	$ 4.4	$ 3.3
Stock options [member] | Calyxt Inc. [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Stock option expire, years	10 years
Expected dividend yield type description	U.S. Treasury zero-coupon yield
Performance Stock Unit [Member] | Calyxt Inc. [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share based arrangement number of other equity instruments granted | shares	311,667
Share based payment expense	$ 0.4	0.2
Performance Stock Unit [Member] | Calyxt Inc. [member] | Bottom of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share Based Payment Arrangement Percentage Payout	0.00%
Performance Stock Unit [Member] | Calyxt Inc. [member] | Top of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share Based Payment Arrangement Percentage Payout	120.00%
Performance Stock Unit [Member] | Calyxt Inc. [member] | Performance Period [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share Based Arrangement Service Period	3 years
Performance Stock Unit [Member] | Calyxt Inc. [member] | Restricted Period [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share Based Arrangement Service Period	2 years
Stock options [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based compensation expense	$ 8.9	13.4	26
Stock options [member] | Calyxt Inc. [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based compensation expense	$ 4	6.8	3.2
Vesting period of warrants	six years
Warrants [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based compensation expense	$ 0.3	0.9	2.3
S A free shares [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based compensation expense	0.9	0.7	$ 0.2
Vesting description			The free shares granted prior to 2018 are subject to a two-year vesting period for French employees and four years for foreign citizens. The free shares granted in 2018 and after are subject to a one-year vesting period for French employees and two-years for foreign citizens.
Dividend yield			0.00%
S A free shares [member] | French employees [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period, years			1 year	2 years
S A free shares [member] | Foreign citizens [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period, years			2 years	4 years
RSU Calyxt 2017 [member] | Calyxt Inc. [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based compensation expense	$ 2.3	$ 4.9	$ 5.5
Vesting description	Restricted stock units generally vest and become unrestricted over five years after the date of grant.

Share-based Payments - Summary

Share-based Payments - Summary of assumptions Vesting Details (Detail) - Equity awards [member] - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of terms and conditions of share-based payment arrangement [line items]
Weighted-Average fair values of stock options granted	$ 7.40	$ 10.19	$ 8.84
Risk-free interest rate	0.00%
Share entitlement per options	$ 1	$ 1	$ 1
Expected term (in years)	6.15		6.25
Vesting conditions	Service	Service	Service
Vesting period	Graded	Graded	Graded
Bottom of Range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate		0.38%	0.13%
Exercise price	$ 8.27	$ 11.06	$ 18.37
Grant date share fair value	$ 9.14	$ 11.32	$ 16
Expected volatility	61.30%	63.80%	63.30%
Expected term (in years)		6.15
Top of Range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate		0.09%	0.21%
Exercise price	$ 15.84	$ 18.25	$ 24.80
Grant date share fair value	$ 15.76	$ 17.80	$ 17.78
Expected volatility	62.80%	66.60%	63.40%
Expected term (in years)		6.25

Share-Based Payments - Summar_2

Share-Based Payments - Summary of Information on Stock Option Activity (Detail) - Stock options [member]	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)	Dec. 31, 2019USD ($)	Dec. 31, 2019EUR (€)	Dec. 31, 2018USD ($)	Dec. 31, 2018EUR (€)
Disclosure Of Number And Weighted Average Exercise Prices Of Share Options and awards [Line Items]
Option exercisable, beginning balance	6,922,172	6,922,172			5,644,044	5,644,044
Option exercisable, granted	0	0
Option exercisable, exercised	0	0
Option exercisable, forfeited or expired	0	0
Option exercisable, ending balance	8,002,398	8,002,398	6,922,172	6,922,172
Weighted- average exercise price per share, beginning balance | €		€ 26.30		€ 27.47
Weighted- average exercise price per share, granted | €		0
Weighted- average exercise price per share, exercised | €		0
Weighted- average exercise price per share, forfeited or expired | €		0
Weighted- average exercise price per share, ending balance | €		€ 25.28		€ 26.30		€ 27.47
Option outstanding, beginning balance	9,672,382	9,672,382			8,978,106	8,978,106
Option outstanding, granted	479,000	479,000	1,650,800	1,650,800
Option outstanding, exercised	(291,053)	(291,053)	0	0
Option outstanding, forfeited or expired	(373,672)	(373,672)	(956,524)	(956,524)
Option outstanding, ending balance	9,486,657	9,486,657	9,672,382	9,672,382
Weighted average exercise price per share, beginning balance | €		€ 24.22				€ 25.36
Weighted average exercise price per share, granted | €		12.54		€ 17.90
Weighted average exercise price per share, exercised | €		17.86		0
Weighted average exercise price per share, forfeited or expired | €		20.61		24.01
Weighted average exercise price per share, ending balance | €		€ 23.97		€ 24.22
Remaining Average Useful Life	5.9y	5.9y	6.8y	6.8y	7.3y	7.3y
Calyxt Inc. [member]
Disclosure Of Number And Weighted Average Exercise Prices Of Share Options and awards [Line Items]
Option exercisable, beginning balance	1,789,567	1,789,567			1,278,038	1,278,038
Option exercisable, granted	0	0	0	0
Option exercisable, exercised	0	0	0	0
Option exercisable, forfeited or expired	0	0	0	0
Option exercisable, ending balance	2,347,665	2,347,665	1,789,567	1,789,567
Weighted- average exercise price per share, beginning balance	$ 8.73				$ 7.45
Weighted- average exercise price per share, granted	0		$ 0
Weighted- average exercise price per share, exercised	0		0
Weighted- average exercise price per share, forfeited or expired	0		0
Weighted- average exercise price per share, ending balance	$ 10.15		$ 8.73
Option outstanding, beginning balance	4,481,359	4,481,359			3,201,887	3,201,887
Option outstanding, granted	887,765	887,765	1,590,000	1,590,000
Option outstanding, exercised	(58,575)	(58,575)	(95,327)	(95,327)
Option outstanding, forfeited or expired	(689,376)	(689,376)	(227,696)	(227,696)
Option outstanding, other activity			12,495	12,495
Option outstanding, ending balance	4,621,173	4,621,173	4,481,359	4,481,359
Weighted average exercise price per share, beginning balance	$ 11.73				$ 10.67
Weighted average exercise price per share, granted	4.67		$ 13.80
Weighted average exercise price per share, exercised	3.60		3.61
Weighted average exercise price per share, forfeited or expired	12.89		14.68
Weighted average exercise price per share, other activity			13.29
Weighted average exercise price per share, ending balance	$ 10.30		$ 11.73
Remaining Average Useful Life	6.2y	6.2y	6.8y	6.8y	8.2y	8.2y

Share-Based Payments - Summar_3

Share-Based Payments - Summary of assumptions Weighted-average Fair Values of Warrants Granted and Assumptions Used for Black-Scholes Option Pricing Model (Detail) - Warrants [member]	12 Months Ended
	Dec. 31, 2017$ / shares	Dec. 31, 2017€ / shares	Dec. 31, 2016$ / shares	Dec. 31, 2016€ / shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Weighted-Average fair values of warrants granted		€ 13.20		€ 9.33
Risk-free interest rate	0.12%	0.12%
Share entitlement per options | $ / shares	$ 1		$ 1
Exercise price		€ 24.34
Grant date share fair value		€ 24.95
Expected volatility	64.70%	64.70%
Expected term (in years)	6	6	6	6
Vesting conditions	Service	Service	Service	Service
Vesting period	Graded	Graded	Graded	Graded
Bottom of Range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate			0.00%	0.00%
Exercise price				€ 18.68
Grant date share fair value				€ 16.42
Expected volatility			62.80%	62.80%
Top of Range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate			0.04%	0.04%
Exercise price				€ 27.37
Grant date share fair value				€ 22.48
Expected volatility			63.10%	63.10%

Share-Based Payments - Summar_4

Share-Based Payments - Summary of Information on Warrants Activity (Detail) - Warrants [member]	12 Months Ended
	Dec. 31, 2020EUR (€)	Dec. 31, 2019EUR (€)	Dec. 31, 2018EUR (€)
Disclosure Of Number And Weighted Average Exercise Prices Of Share Options and awards [Line Items]
Option exercisable, beginning balance	852,260		687,252
Warrants exercisable, granted	0		0
Warrants exercisable, exercised	0		0
Warrants exercisable, forfeited or expired	0		0
Option exercisable, ending balance	899,225	852,260
Weighted- average exercise price per share, beginning balance	€ 35.35		€ 27.74
Weighted- average exercise price per share, granted	0		0
Weighted- average exercise price per share, exercised		€ 0
Weighted- average exercise price per share, forfeited or expired	0		€ 0
Weighted- average exercise price per share, ending balance	€ 27.15	€ 35.35
Option outstanding, beginning balance	918,927		918,927
Warrants outstanding, granted	0	0
Warrants outstanding, exercised	(19,702)	0
Warrants outstanding, forfeited or expired	0	0
Option outstanding, ending balance	899,225	918,927
Weighted average exercise price per share, beginning balance	€ 35.12		€ 26.74
Weighted average exercise price per share, granted	0	€ 0
Weighted average exercise price per share, exercised	8.28	0
Weighted average exercise price per share, forfeited or expired	0	0
Weighted average exercise price per share, ending balance	€ 27.15	€ 35.12
Remaining Average Useful Life	5.3y	6.9y	7.2y

Share-Based Payment - Summary o

Share-Based Payment - Summary of Number of Shares Outstanding and Weighted Average Grant Date Fair Value (Detail) - S A free shares [member]	12 Months Ended
	Dec. 31, 2020EUR (€)		Dec. 31, 2019EUR (€)
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of free shares outstanding, beginning balance	67,000		71,600
Number of free shares outstanding, granted	591,685		57,000
Number of free shares outstanding, vested	(3,000)		(35,600)
Number of free shares outstanding, cancelled	(26,035)		(26,000)
Number of free shares outstanding, ending balance	629,650		67,000
Weighted average grant date fair value, beginning balance			€ 27.37
Weighted average grant date fair Value, granted	€ 20.10	[1]	13.04
Weighted average grant date fair value, vested	23.84		25.74
Weighted average grant date fair Value, cancelled	16.45		21.65
Weighted average grant date fair value, ending balance	€ 19.59		€ 13.98
[1]	423,285 free shares have been granted in October, 2020 under the 2018 Stock Option Plan and are under non-market performance vesting conditions and with a minimum vesting period of three years. These free shares have been granted to a large number of our employees.

Share-Based Payment - Summary_2

Share-Based Payment - Summary of Number of Shares Outstanding and Weighted Average Grant Date Fair Value (Parenthetical) (Detail) - shares	1 Months Ended	12 Months Ended
	Oct. 31, 2020	Dec. 31, 2020
Disclosure of terms and conditions of share-based payment arrangement [line items]
NumberOfInstrumentsOtherEquityInstrumentsGranted		1,070,685
Free Shares [member] | 2018 Stock Option Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
NumberOfInstrumentsOtherEquityInstrumentsGranted	423,285
Number of free shares void		6,535
Free Shares [member] | Bottom of Range [member] | 2018 Stock Option Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Minimum vesting period	2 years
Free Shares [member] | Top of Range [member] | 2018 Stock Option Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Minimum vesting period	3 years

Share-Based Payments - Calyxt E

Share-Based Payments - Calyxt Eqity Summary of assumptions Vesting Details (Detail) - Calyxt Inc. [member] - Stock options [member] - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of terms and conditions of share-based payment arrangement [line items]
Weighted-Average fair values of stock options granted	$ 3.24	$ 10.18	$ 9.09
Share entitlement per options	$ 1	$ 1	$ 1
Vesting conditions	Service	Service	Service
Vesting period	Graded	Graded	Graded
Bottom of Range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate	0.30%	1.70%	2.20%
Exercise price	$ 3.22	$ 4.05	$ 14.24
Grant date share fair value	$ 3.22	$ 4.05	$ 14.24
Expected volatility	77.40%	52.60%	40.90%
Expected term (in years)	6.0	6.8	5.6
Top of Range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Risk-free interest rate	1.70%	2.50%	3.00%
Exercise price	$ 7.30	$ 15.39	$ 23.39
Grant date share fair value	$ 7.30	$ 15.39	$ 23.39
Expected volatility	81.20%	78.90%	57.20%
Expected term (in years)	10.0	10.0	10.0

Share-Based Payments - Summar_5

Share-Based Payments - Summary of Number of Shares Outstanding and Weighted Average Grant Date Fair Value (Detail) - RSU Calyxt 2017 [member] - Calyxt Inc. [member]	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of free shares outstanding, beginning balance	813,526	1,051,414
Number of restricted stock units outstanding, granted	105,633	100,000
Number of restricted stock units outstanding, vested	(309,693)	(324,043)
Number of restricted stock units outstanding, cancelled	(61,659)	(13,845)
Number of free shares outstanding, ending balance	547,807	813,526
Weighted average grant date fair value, beginning balance		$ 14.11
Weighted average grant date fair Value, granted	$ 6.54	12.48
Weighted average grant date fair value, vested	10.08	9.69
Weighted average grant date fair Value, cancelled	10.80	12.72
Weighted average grant date fair value, ending balance	$ 9.49	$ 10.31

Share-Based Payments - Detailed

Share-Based Payments - Detailed Description Inputs Stock Options Granted Performance Stock (Detail) - Performance Stock Unit [Member] - Calyxt [Member]	Jun. 28, 2019Years$ / shares
Disclosure Description Of Inputs Stock Options Granted Performance Stock [Line Items]
Estimated fair values of performance stock units granted | $ / shares	$ 7.06
Assumptions:
Risk-free interest rate	1.71%
Expected volatility	75.00%
Expected term (in years) | Years	3

Share-Based Payments - Detail_2

Share-Based Payments - Detailed Disclosure Detail Of Stock Unit Activity Performance Stock (Detail)	12 Months Ended
	Dec. 31, 2020USD ($)shares
Disclosure Detail Of Stock Unit Activity Performance Stock [Line Items]
Number of performance stock units outstanding, Granted	1,070,685
Number of performance stock units outstanding, Vested	313,755
Number of performance stock units outstanding, Cancelled	399,707
Performance Stock Unit [Member] | Calyxt [Member]
Disclosure Detail Of Stock Unit Activity Performance Stock [Line Items]
Number of free shares outstanding, beginning balance	311,667
Number of performance stock units outstanding, Granted	0
Number of performance stock units outstanding, Vested	0
Number of performance stock units outstanding, Cancelled	0
Number of free shares outstanding, ending balance	311,667
Weighted average grant date fair value, beginning balance | $	$ 7.06
Weighted average grant date fair Value, granted | $	0
Weighted average grant date fair value, vested | $	0
Weighted average grant date fair Value, cancelled | $	0
Weighted average grant date fair value, ending balance | $	$ 7.06

Earnings Per Share - Details of

Earnings Per Share - Details of Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings per share [abstract]
Net income (loss) attributable to shareholders of Cellectis ($ in thousands)	$ (81,074)	$ (102,091)	$ (78,693)
Adjusted weighted average number of outstanding shares, used to calculate both basic and diluted net result per share	42,503,447	42,442,136	40,774,197
Basic net income (loss) attributable to shareholders of Cellectis per share ( $ /share)	$ (1.91)	$ (2.41)	$ (1.93)
Diluted net income (loss) attributable to shareholders of Cellectis per share ( $ /share)	$ (1.91)	$ (2.41)	$ (1.93)

Provisions - Summary of Provisi

Provisions - Summary of Provisions for Termination Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of other provisions [line items]
Beginning balance	$ 6,598
Additions	968	$ 4,323
Amounts used during the period	(2,272)	(2,099)
Pension, Reversals	(1,034)	(92)
OCI	881	253
Ending balance	5,141	6,598
Non current provisions beginning balance	2,855
Non current provisions additions	410	314
Non current provisions OCI	745	263
Non current provisions Ending balance	4,010	2,855
Current provisions beginning balance	3,743
Current provisions additions	558	4,009
Current provisions Amounts used during period	(2,272)	(2,099)
Current provisions Reversals	(1,034)	(92)
Current provisions OCI	136	(10)
Current provisions Ending balance	1,131	3,743
Restated [member]
Disclosure of other provisions [line items]
Beginning balance	6,598	3,169
Ending balance		6,598
Non current provisions beginning balance	2,855	2,278
Non current provisions Ending balance		2,855
Current provisions beginning balance	3,743	891
Current provisions Ending balance		3,743
Reclassification [member]
Disclosure of other provisions [line items]
Beginning balance		1,043
Current provisions beginning balance		1,043
Pension [member]
Disclosure of other provisions [line items]
Beginning balance	2,855
Pension, Additions	410	314
OCI	745	263
Ending balance	4,010	2,855
Pension [member] | Restated [member]
Disclosure of other provisions [line items]
Beginning balance	2,855	2,278
Ending balance		2,855
Loss on Contract [member]
Disclosure of other provisions [line items]
Loss on contract, Beginning balance	272
Loss on contract, Additions		690
Loss on contract, Amounts used during the period	(272)	(1,461)
Loss on contract, OCI
Loss on contract, Ending balance		272
Loss on Contract [member] | Restated [member]
Disclosure of other provisions [line items]
Loss on contract, Beginning balance	272
Loss on contract, Ending balance		272
Loss on Contract [member] | Reclassification [member]
Disclosure of other provisions [line items]
Loss on contract, Beginning balance		1,043
Employee Litigation and Severance [member]
Disclosure of other provisions [line items]
Additions	200	700
Employee litigation and severance, Beginning balance	639
Employee litigation and severance, Additions	229	715
Employee litigation and severance, Amounts used during the period	(308)	(43)
Employee litigation and severance, Reversals	(49)	(75)
Employee litigation and severance, OCI	49	1
Employee litigation and severance, Ending balance	560	639
Employee Litigation and Severance [member] | Restated [member]
Disclosure of other provisions [line items]
Employee litigation and severance, Beginning balance	639	41
Employee litigation and severance, Ending balance		639
Commercial litigation [member]
Disclosure of other provisions [line items]
Additions	300
Commercial litigation, Beginning balance	2,832
Commercial litigation, Additions	329	2,604
Commercial litigation, Amounts used during the period	(1,692)	(595)
Commercial litigation, Reversals	(985)	(17)
Commercial litigation, OCI	86	(11)
Commercial litigation, Ending balance	571	2,832
Commercial litigation [member] | Restated [member]
Disclosure of other provisions [line items]
Commercial litigation, Beginning balance	$ 2,832	850
Commercial litigation, Ending balance		$ 2,832

Provisions - Additional Informa

Provisions - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of provisions [line items]
Provisions for termination benefits	$ 968	$ 4,323
Defined benefit plan	4,010	2,855	$ 2,278	$ 2,194
Operating charges with suppliers [Member]
Disclosure of provisions [line items]
Provisions for termination benefits		2,600
Pension service cost [member]
Disclosure of provisions [line items]
Provisions for termination benefits	400	300
Operating lease rentals [member]
Disclosure of provisions [line items]
Provisions for termination benefits	300	700
Commercial litigation [member]
Disclosure of provisions [line items]
Provisions for termination benefits	300
Discontinuation Of The Lease [Member]
Disclosure of provisions [line items]
Provisions for termination benefits		700
Employee Litigation and Severance [member]
Disclosure of provisions [line items]
Provisions for termination benefits	200	700
Settlement of Employee Litigation [Member]
Disclosure of provisions [line items]
Provisions for termination benefits	300
Termination of Commercial Litigation [Member]
Disclosure of provisions [line items]
Provisions for termination benefits	2,700
France [member]
Disclosure of provisions [line items]
Defined benefit plan	$ 1,500	$ 1,100	$ 1,500

Provisions - Schedule of Estima

Provisions - Schedule of Estimation of Retirement Indemnity to Employee (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of defined benefit plans [abstract]
% social security contributions	45.00%	45.00%	45.00%
Salary increases	3.50%	3.50%	3.50%
Discount rate	0.68%	1.00%	1.75%
Terms of retirement	Voluntary retirement	Voluntary retirement	Voluntary retirement
Retirement age	65 years	65 years	65 years

Provisions - Summary of Net Def

Provisions - Summary of Net Defined Benefit Liability and Components (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of net defined benefit liability (asset) [abstract]
Beginning balance	$ (2,855)	$ (2,278)	$ (2,194)
Current service cost	(381)	(275)	(276)
Interest cost	(29)	(39)	(38)
Benefit paid			54
Actuarial gains and losses	(411)	(303)	70
Reclassification/CTA	(334)	40	105
Ending balance	$ (4,010)	$ (2,855)	$ (2,278)

Commitments - Schedule of Commi

Commitments - Schedule of Commitments (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Disclosure of contingent liabilities [line items]
Total commitments	$ 52,381
License Agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	19,110
Manufacturing Agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	942
Other Agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	21,704
Clinical & R&D agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	1,353
Construction agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	9,272
Less than One Year [member]
Disclosure of contingent liabilities [line items]
Total commitments	34,321
Less than One Year [member] | License Agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	1,530
Less than One Year [member] | Manufacturing Agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	942
Less than One Year [member] | Other Agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	21,631
Less than One Year [member] | Clinical & R&D agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	946
Less than One Year [member] | Construction agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	9,272
1-3 years [member]
Disclosure of contingent liabilities [line items]
Total commitments	3,540
1-3 years [member] | License Agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	3,060
1-3 years [member] | Other Agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	72
1-3 years [member] | Clinical & R&D agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	408
3-5 years [member]
Disclosure of contingent liabilities [line items]
Total commitments	3,060
3-5 years [member] | License Agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	3,060
More than Five Years [member]
Disclosure of contingent liabilities [line items]
Total commitments	11,460
More than Five Years [member] | License Agreements [member]
Disclosure of contingent liabilities [line items]
Total commitments	$ 11,460

Related Parties - Additional In

Related Parties - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020USD ($)Agreementshares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2020€ / shares
Disclosure of transactions between related parties [line items]
Key management personnel compensation, short-term employee benefits | $	$ 6,300,000	$ 5,200,000	$ 4,400,000
Key management personnel compensation, share-based payments in shares	380,100
Key management personnel non-cash stock-based compensation expense recognized | $	$ 700,000
Mr. Godard [member]
Disclosure of transactions between related parties [line items]
Number of service agreements | Agreement	2
Compensation paid for consultancy services | $	$ 58,000	$ 71,000	$ 70,000
Transactions with related parties, amount outstanding | $	$ 0
Mr. Godard [member] | Non-Employee Warrant One [member]
Disclosure of transactions between related parties [line items]
Number of non-employee warrants exercisable to obtain shares	220,175
Number of shares to be obtained upon exercise of warrants, strike price | € / shares				€ 38.45
Mr. Godard [member] | Non-Employee Warrant Two [member]
Disclosure of transactions between related parties [line items]
Number of non-employee warrants exercisable to obtain shares	50,000
Number of shares to be obtained upon exercise of warrants	50,000
Number of shares to be obtained upon exercise of warrants, strike price | € / shares				28.01
Mr. Godard [member] | Non-Employee Warrant Three [member]
Disclosure of transactions between related parties [line items]
Number of non-employee warrants exercisable to obtain shares	40,175
Number of shares to be obtained upon exercise of warrants	40,175
Number of shares to be obtained upon exercise of warrants, strike price | € / shares				27.37
Mr. Godard [member] | Non-Employee Warrant Four [member]
Disclosure of transactions between related parties [line items]
Number of non-employee warrants exercisable to obtain shares	40,000
Number of shares to be obtained upon exercise of warrants	40,000
Number of shares to be obtained upon exercise of warrants, strike price | € / shares				18.68
Mr. Godard [member] | Non Employee Warrant Five [member]
Disclosure of transactions between related parties [line items]
Number of non-employee warrants exercisable to obtain shares	40,000
Number of shares to be obtained upon exercise of warrants	40,000
Number of shares to be obtained upon exercise of warrants, strike price | € / shares				€ 24.34

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($) $ in Millions	Feb. 19, 2021	Feb. 16, 2021	Dec. 31, 2020
Disclosure of non-adjusting events after reporting period [line items]
Key management personnel non-cash stock-based compensation expense recognized			$ 0.7
Strategic research and development collaboration [Member] | Cytovia Therapeutics, Inc. [Member]
Disclosure of non-adjusting events after reporting period [line items]
Revenue from collaborative arrangement		$ 760
Equity interest receivable value		15
Upfront cash payments		$ 15
Compensation and benefits as part termination [member] | Chief Executive Officer [Member]
Disclosure of non-adjusting events after reporting period [line items]
Key management personnel cash expense for separation related payments	$ 2.3
Key management personnel non-cash stock-based compensation expense recognized	0.1
Compensation and benefits as part termination [member] | Chief Executive Officer [Member] | Unvested stock awards [member]
Disclosure of non-adjusting events after reporting period [line items]
Key management personnel non-cash stock-based compensation expense recognized	$ 2.5