ADC Therapeutics (ADCT) 20-F 18 Mar 21 2020 FY Annual report (foreign) Financial data

Cover Page

Cover Page	12 Months Ended
	Dec. 31, 2020shares
Entity Addresses [Line Items]
Document Type	20-F
Document Registration Statement	false
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Annual Report	true
Document Transition Report	false
Document Shell Company Report	false
Entity File Number	001-39071
Entity Registrant Name	ADC Therapeutics SA
Entity Incorporation, State or Country Code	V8
Entity Address, Address Line One	Biopôle
Entity Address, Address Line Two	Route de la Corniche 3B
Entity Address, Postal Zip Code	1066
Entity Address, Country	CH
Entity Address, City or Town	Epalinges
Title of 12(b) Security	Common Shares, par value CHF 0.08 per share
Trading Symbol	ADCT
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding	76,721,543
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Document Accounting Standard	International Financial Reporting Standards
Entity Shell Company	false
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Central Index Key	0001771910
Business Contact
Entity Addresses [Line Items]
Entity Address, Address Line One	430 Mountain Avenue, 4th Floor
Entity Address, Postal Zip Code	07974
Entity Address, State or Province	NJ
Contact Personnel Name	Jennifer Creel
City Area Code	908
Local Phone Number	546-5556
Entity Address, City or Town	Murray Hill

Consolidated Statement of Opera

Consolidated Statement of Operation - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Profit or loss [abstract]
Contract revenue	$ 0	$ 2,340,000	$ 1,140,000
Research and development expenses	(142,032,000)	(107,537,000)	(118,313,000)
Selling and marketing expenses	(22,101,000)	0	0
General and administrative expenses	(55,130,000)	(14,202,000)	(8,768,000)
Total operating expense	(219,263,000)	(121,739,000)	(127,081,000)
Loss from operations	(219,263,000)	(119,399,000)	(125,941,000)
Other income (expense)
Other income	584,000	1,655,000	0
Convertible loans, derivatives, change in fair value (expense)	(45,411,000)	0	0
Convertible loans, first tranche, derivative, transaction costs	(1,571,000)	0	0
Share of results with joint venture	24,368,000	0	0
Financial income	832,000	2,253,000	2,856,000
Financial expense	(4,926,000)	(156,000)	0
Exchange differences (loss) gain	(576,000)	(255,000)	213,000
Total other (expense) income	(26,700,000)	3,497,000	3,069,000
Loss before taxes	(245,963,000)	(115,902,000)	(122,872,000)
Income tax (expense)	(327,000)	(582,000)	(224,000)
Net loss	(246,290,000)	(116,484,000)	(123,096,000)
Net loss attributable to:
Owners of the parent	$ (246,290,000)	$ (116,484,000)	$ (123,096,000)
Net loss per share
Basic and diluted net loss per share (in USD per share)	$ (3.77)	$ (2.36)	$ (2.64)

Consolidated Statement of Compr

Consolidated Statement of Comprehensive (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Profit or loss [abstract]
Net loss	$ (246,290)	$ (116,484)	$ (123,096)
Items that will not be reclassified to profit or loss
Remeasurements of defined benefit pension	(305)	(1,346)	(193)
Total items that will not be reclassified to profit or loss	(305)	(1,346)	(193)
Items that may be reclassified subsequently to profit or loss
Currency translation differences	176	112	(79)
Total items that may be reclassified subsequently to profit or loss	176	112	(79)
Other comprehensive loss	(129)	(1,234)	(272)
Total comprehensive loss	(246,419)	(117,718)	(123,368)
Attributable to:
Owners of the parent	$ (246,419)	$ (117,718)	$ (123,368)

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 439,195	$ 115,551
Other current assets	11,255	7,055
Total current assets	450,450	122,606
Non-current assets
Property, plant and equipment	1,629	1,376
Right-of-use assets	3,129	4,898
Intangible assets	10,179	8,434
Interest in joint venture	47,908	0
Other long-term assets	397	368
Total non-current assets	63,242	15,076
Total assets	513,692	137,682
Current liabilities
Accounts payable	5,279	3,329
Other current liabilities	30,375	15,430
Lease liabilities, short-term	1,002	1,132
Current income tax payable	149	52
Convertible loans, short-term		0
Total current liabilities	40,436	19,943
Non-current liabilities
Convertible loans, long-term		0
Convertible loans, derivatives	73,208	0
Deferred gain of joint venture	23,539	0
Lease liabilities, long-term	2,465	3,899
Defined benefit pension liabilities	3,543	2,684
Other non-current liabilities	221	0
Total non-current liabilities	137,751	6,583
Total liabilities	178,187	26,526
Equity attributable to owners of the parent
Share capital	6,314	4,361
Share premium	981,056	549,922
Treasury shares	(4)	(100)
Other reserves	42,753	5,473
Cumulative translation adjustments	245	69
Cumulative translation adjustments	(694,859)	(448,569)
Total equity attributable to owners of the parent	335,505	111,156
Total liabilities and equity	$ 513,692	$ 137,682

Consolidated Statement of Chang

Consolidated Statement of Changes in Equity - USD ($) $ in Thousands	Total	Share capital	Share premium	Other reserves	Treasury shares	Cumulative translation adjustment	Accumulated losses
Equity, beginning balance at Dec. 31, 2017	$ 249,166	$ 397	$ 452,296	$ 5,426	$ 0	$ 36	$ (208,989)
Total comprehensive loss	(123,368)			(193)		(79)	(123,096)
Net loss	(123,096)						(123,096)
Other comprehensive loss	(272)			(193)		(79)
Translation adjustment	(79)					(79)
Remeasurements of defined benefit pension	(193)			(193)
Total transactions with owners	445	4	(28)	469
Issue of share capital / capital contributions	4	4
Transaction costs	(28)		(28)
Share-based compensation expense	469			469
Equity, ending balance at Dec. 31, 2018	126,243	401	452,268	5,702	0	(43)	(332,085)
Total comprehensive loss	(117,718)			(1,346)		112	(116,484)
Net loss	(116,484)						(116,484)
Other comprehensive loss	(1,234)			(1,346)		112
Translation adjustment	112					112
Remeasurements of defined benefit pension	(1,346)			(1,346)
Total transactions with owners	102,631	3,960	97,654	1,117	(100)
Issue of share capital / capital contributions	103,392	171	103,221
Transaction costs	(1,778)		(1,778)
Transfer from share premium for par value increase	0	3,789	(3,789)
Purchase of treasury shares	(141)				(141)
Sale of treasury shares	41				41
Share-based compensation expense	1,117			1,117
Equity, ending balance at Dec. 31, 2019	111,156	4,361	549,922	5,473	(100)	69	(448,569)
Total comprehensive loss	(246,419)			(305)		176	(246,290)
Net loss	(246,290)						(246,290)
Other comprehensive loss	(129)			(305)		176
Translation adjustment	176					176
Remeasurements of defined benefit pension	(305)			(305)
Total transactions with owners	470,768	1,953	431,134	37,585	96
Shares surrendered to redeem share purchase plan promissory notes	0		11,208		(11,208)
Issuance of shares through capitalization of reserves	0	393	(393)
Issuance of shares to be held as treasury shares	0	34			(34)
Grant of shares to settle 2014 incentive plan awards	0		(29)		29
Issuance of shares at initial public offering	232,668	1,007	231,661
Sale of shares under greenshoe option	34,900		23,591		11,309
Transaction costs, initial public offering and greenshoe option	(23,355)		(23,355)
Issuance of shares at follow-on offering	204,000	519	203,481
Transaction costs, follow-on offering	(15,084)		(15,084)
Exercise of options	54		54
Share-based compensation expense	37,585			37,585
Equity, ending balance at Dec. 31, 2020	$ 335,505	$ 6,314	$ 981,056	$ 42,753	$ (4)	$ 245	$ (694,859)

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash used in operating activities
Loss for the year	$ (246,290)	$ (116,484)	$ (123,096)
Adjustments for non-monetary items:
Share-based compensation expense	37,585	1,117	469
Depreciation of property, plant and equipment	774	552	488
Depreciation of right-of-use assets	1,151	1,064	0
Amortization and impairment of intangible assets	263	30	252
Share of results in joint venture	(24,368)	0	0
Convertible loans, derivatives, increase in fair value	45,411	0	0
Change in defined benefit pension liabilities	276	(53)	119
Financial income	(832)	(1,696)	(1,847)
Financial expense	4,820	15	0
Exchange differences	476	128	(29)
Income taxes	327	582	224
Operating loss before working capital changes	(180,407)	(114,745)	(123,420)
Decrease in trade accounts receivable	0	192	895
(Increase) in other current assets	(4,505)	(3,841)	(967)
(Decrease) in contract liability (short and long term)	0	(2,340)	(1,140)
Increase (decrease) in trade accounts payable	1,921	(3,425)	(858)
Increase in accrued liabilities and other payables	14,946	1,720	3,262
Cash used in operating activities	(168,729)	(121,581)	(121,362)
Interest received	797	1,164	1,051
Interest paid	(1,557)	(157)	0
Interest	105	141	0
Tax paid	(29)	(290)	(185)
Cash used in operating activities	(168,045)	(122,439)	(122,228)
Cash used in investing activities
Payment for purchases of property, plant and equipment	(801)	(358)	(944)
Payment for purchases of intangible assets	(2,008)	(1,790)	(1,526)
Payment for rent deposits	(19)	(100)	(36)
Net cash used in investing activities	(2,828)	(2,248)	(2,506)
Cash from / (used in) financing activities
Proceeds from capital contributions, net of transaction costs	0	101,614	(24)
Proceeds from public offering of common shares, net of transaction costs	433,158	0	0
Proceeds from convertible loans, net of transaction costs	62,898	0	0
Acquisition of treasury shares	0	(141)	0
Sale of treasury shares	0	41	0
Proceeds from the exercise of stock options	54	0	0
Principal portion of lease obligations payments	(1,144)	(1,002)	0
Net cash from / (used in) financing activities	494,966	100,512	(24)
Net increase (decrease) in cash and cash equivalents	323,409	(23,317)	(123,892)
Exchange gains / (losses) on cash and cash equivalents	235	61	(53)
Cash and cash equivalents at beginning of year	115,551	138,807	262,752
Cash and cash equivalents at end of year	439,195	115,551	138,807
Supplemental Non-Cash Investing Information
Capital expenditures recorded in Other current liabilities	$ 220	$ 0	$ 0

Corporate Information

Corporate Information	12 Months Ended
	Dec. 31, 2020
Corporate Information And Statement Of IFRS Compliance [Abstract]
Corporate Information	Corporate information ADC Therapeutics SA (the “Company” or “ADCT”) was incorporated on June 6, 2011 under the laws of Switzerland. The registered office of the Company is located at Route de la Corniche 3B, 1066 Epalinges, Switzerland. The Company controls two wholly-owned subsidiaries: ADC Therapeutics America, Inc. (“ADCT America”), which was incorporated in Delaware, USA on December 10, 2014, and ADC Therapeutics (UK) Ltd (“ADCT UK”), which was incorporated in England on December 12, 2014. The Company and its two subsidiaries form the ADCT Group (the “Group”). The Group is focused on the development of antibody drug conjugates, including research, development, human clinical trials, regulatory approval and commercialization. Antibody drug conjugates (“ADCs”) are drug constructs which combine monoclonal antibodies specific to particular types of cells with cytotoxic molecules or warheads which seek to kill cancer cells to which the ADC attaches. ADCs have extensive potential therapeutic applications in cancer. The Group’s core technology platform is based on the development and commercial exploitation of chemistry acquired under license from Spirogen Ltd in 2011. The license agreement, as subsequently amended in 2013, gives the Company the right to develop up to eleven specific ADCs as well as ten non-ADCs using Spirogen Ltd's intellectual property and technology in warhead and linker chemistry. These Group consolidated financial statements were authorized for issue by the Board of Directors on March 18, 2021.

Basis of preparation

Basis of preparation	12 Months Ended
	Dec. 31, 2020
Corporate Information And Statement Of IFRS Compliance [Abstract]
Basis of preparation	Basis of preparation (i) Compliance with International Financial Reporting Standards The ADCT Group consolidated financial statements have been prepared in accordance with International Financial Reporting Standards (IFRS) as issued by the International Accounting Standards Board (IASB). As of December 31, 2020, the financial statements are presented in thousand dollars (KUSD). (ii) Historical Cost Convention The consolidated financial statements have been prepared under the historical cost convention, except for the defined benefit pension liabilities, where plan assets are measured at fair value, and the embedded derivative conversion feature and the derivative associated with the convertible loans (see note 21 “Convertible loans”), which are measured at fair value. (iii) Going concern basis ADCT is a late clinical-stage company developing innovative therapeutics. The Group is exposed to all risks inherent in establishing and developing its business, including the substantial uncertainty that current projects will succeed. The Group's success may also depend on its ability to: • establish and maintain a strong patent position and protection; • develop, gain regulatory approval and commercialize drug products; • enter into collaborations with partners in the pharmaceutical industry; • acquire and retain key personnel; and • acquire additional funding to support its operations. Since its incorporation, the Group has primarily funded its growth through capital increases, both equity and debt, and additional funds provided by research collaborations. During the 2020 fiscal year, the Company issued common shares through an initial public and follow-on offering (see note 2(vi) and 2(vii)) and the issuance of convertible loans (see note 21, “Convertible loans”). The Group does not have recourse to bank loans. As a result, the Group is not exposed to liquidity risk through requests for early repayment of loans, other than, pursuant to the convertible loans, it must maintain a balance of at least USD 50 million in cash and cash equivalents at the end of each quarter. As of December 31, 2020, the Group’s cash and cash equivalents amounted to KUSD 439,195 (December 31, 2019: KUSD 115,551). Management believes that the Group has sufficient financial resources to cover its operating costs for at least the next 12 months from the date of issuance of these consolidated financial statements and as a result, is presenting these consolidated financial statements of the Group on a going concern basis. (iv) Share split On September 19, 2019, the Company effected a one-to-15,625 share split of its outstanding shares (see note 23, “Share capital”). Accordingly, all share and per share amounts for all periods presented in these consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this share split. (v) Share consolidation On April 24, 2020, the Company effected a five-to-four share consolidation of its outstanding shares (see note 23, “Share capital”). Accordingly, all share and per share amounts for all periods presented in these consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this share consolidation. (vi) Initial Public Offering (IPO) On May 19, 2020, the Company completed an IPO on the New York Stock Exchange (“NYSE”) in which it issued and sold an aggregate of 14,082,475 common shares at USD 19.00 per share, which included 1,836,844 common shares issued and sold pursuant to the underwriters’ exercise in full of their option to purchase additional common shares. The gross proceeds from the IPO were USD 267.6 million, and net proceeds were USD 244.2 million after deducting underwriting discounts and commissions as well as fees and expenses payable by the Company. The IPO resulted in a gross increase of USD 255.3 million in the Company’s share premium account prior to transaction costs associated with the IPO share issuance of USD 4.7 million and underwriting discounts and commissions of USD 18.7 million, both of which were charged directly against the Company’s share premium account. Further details are contained in note 23, “Share capital”. (vii) Follow-On Public Offering On September 28, 2020, the Company completed a public offering on the NYSE in which it issued and sold 6,000,000 common shares at USD 34.00 per share. The gross proceeds of the public offering were USD 204.0 million, and net proceeds of USD 188.9 million after deducting underwriting discounts and commissions as well as fees and expenses payable by the Company. The public offering resulted in a gross increase of USD 203.5 million in the Company’s share premium account prior to transaction costs associated with the public offering share issuance of USD 2.9 million and underwriting discounts and commissions of USD 12.2 million, both of which were charged directly against the Company’s share premium account. Further details are contained in note 23, “Share capital”. (viii) Overland Joint Venture On December 14, 2020, the Company announced the formation of a new joint venture company, Overland ADCT BioPharma (CY) Limited (“Overland ADCT BioPharma”), with Overland Pharmaceuticals (“Overland”), a fully integrated biopharmaceutical company backed by Hillhouse Capital. Overland ADCT BioPharma will develop and commercialize four of the Company’s ADC product candidates, loncastuximab tesirine (“Lonca” and previously known as ADCT-402), ADCT-601, ADCT-602 and ADCT-901 (collectively, the “Licensed Products”), in greater China and Singapore (the “Territory”). The Company agrees to supply product to Overland ADCT BioPharma for its drug development and commercialization under a supply agreement which will be entered into between the parties. Under the terms of the license agreement between the Company and Overland ADCT BioPharma, the Company licensed exclusive development and commercialization rights to the Licensed Products (the “Licensed IP”) in the Territory to Overland ADCT BioPharma. Overland invested USD 50.0 million in Overland ADCT BioPharma, and is obligated to pay the Company potential development milestone payments related to ADCT-601, ADCT-602 and ADCT-901, for a 51% equity interest. The Company received a 49% equity interest in exchange for contribution of the Licensed IP. The Company and Overland will both appoint an equal number of nominees to the board of directors of Overland ADCT BioPharma which will include the Chief Executive Officer of Overland ADCT BioPharma (“Overland CEO”). Currently, a search is underway for the Overland CEO. Pursuant to the license agreement, the Company may also earn low to mid-single digit royalties on net sales of the Licensed Products. In addition, Overland ADCT BioPharma may elect to participate in the Company’s global clinical trials. The Company also received an option, which it may exercise at its sole discretion, to exchange any or all of its equity interest in Overland ADCT BioPharma into an equity interest in Overland upon an initial public offering of Overland. Given the uncertainty of an initial public offering of Overland, the Company did not assign any value to the option. In connection with the formation of Overland ADCT BioPharma, the Company determined the fair value of its equity interest by implying a total equity value of Overland ADCT BioPharma using Overland’s investment of USD 50.0 million and the fair value of the contingent milestone consideration for Overland’s 51% equity interest. The fair value of the contingent consideration was determined to be nominal due to the high uncertainty related to achieving certain conditions associated with the contingent consideration as of the closing date. The fair value of the Company’s equity interest was determined to be KUSD 48,040, which resulted in the Company recognizing a gain of KUSD 24,501 and a deferred gain of KUSD 23,539. The gain was recognized within Share of results with joint venture in the Company’s Consolidated Statement of Operation for the year ended December 31, 2020. The deferred gain is recorded in Deferred gain of joint venture in the Company’s Consolidated Balance Sheet. In accordance with International Accounting Standard 28 Investments in Associates and Joint Ventures (“IAS 28”), the gain resulting from the transaction was only recognized to the extent of the unrelated investor’s equity interest in the joint venture, or 51%. The Company will begin to recognize the deferred gain upon the commercialization by Overland ADCT BioPharma of any or all the Licensed Products in the Territory. The deferred gain will be recognized over the estimated commercialization period in which a Licensed Product is developed and approved using a systematic approach that approximates the pattern of consumption of the Licensed IP by Overland ADCT BioPharma. Under the terms of the transaction, the Company may receive variable consideration in the form of contingent milestones and royalties. This consideration is dependent upon the success of the programs subject to the license. The Company will recognize those amounts within other income in the Company’s Consolidated Statement of Operation only to the extent a significant reversal in the amount of cumulative income recognized is not probable of occurring when the uncertainty associated with the variable consideration is subsequently resolved. In accordance with the terms of the transaction, the Company and Overland jointly control Overland ADCT BioPharma, as they must act together to direct the relevant activities of Overland ADCT BioPharma that would significantly affect its returns. As such, the Company concluded that it did not have the power to unilaterally direct these activities in accordance with International Financial Reporting Standards 10 Consolidated Financial Statements (“IFRS 10”). Therefore, the Company’s equity interest in Overland ADCT BioPharma is accounted for under the equity method of accounting in accordance with IAS 28 and is recorded in Interest in joint venture in the Company’s Consolidated Balance Sheet as of December 31, 2020. The Company’s proportionate share of Overland ADCT BioPharma’s net loss is recorded within Share of results with joint venture in the Company’s Consolidated Statement of Operation, which was KUSD 132 from the closing of the transaction to December 31, 2020. (in KUSD) Interest in joint venture January 1, 2020 — Initial investment 48,040 Share of results with joint venture (132) December 31, 2020 47,908 The tables below provide summarized financial information for Overland ADCT BioPharma that are material to the Company. The following information reflects the amounts presented in the financial statements of Overland ADCT BioPharma and not the Company’s share of those amounts. Summarized Balance Sheet As of December 31, 2020 Cash and cash equivalents 50,000 Intangible assets 48,040 Total liabilities 269 Net assets 97,771 Summarized Statement of Comprehensive Loss For the period from December 14, 2020 through December 31, 2020 Operating expenses 269 Net loss 269 (ix) COVID – 19 The COVID-19 pandemic has negatively impacted the economies of most countries around the world. The Group’s operations, similar to those of other life sciences companies, have been impacted by the COVID-19 pandemic. As the Group advances its clinical programs, it is in close contact with its principal investigators and clinical sites, which are located in jurisdictions affected by the COVID-19 pandemic, and is assessing the impact of the COVID-19 pandemic on its clinical trials, expected timelines and costs on an ongoing basis. In light of recent developments relating to the COVID-19 pandemic, the primary focus of healthcare providers and hospitals is currently on fighting the novel coronavirus. In addition, in response to the spread of COVID-19, the Group has modified its business practices, including

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies, Changes In Accounting Estimates And Errors [Abstract]
Significant Accounting Policies	Significant accounting policies The principal accounting policies applied in the preparation of these consolidated financial statements are set out below. These policies have been consistently applied to all the years presented, unless otherwise stated. 3.1. Consolidation The annual closing date of the individual financial statements is December 31. Subsidiaries are all entities over which the Company has control. The Company controls an entity when the Company is exposed to, or has rights to, variable returns from its involvement with the entity and has the ability to affect those returns through its power over the entity. Subsidiaries are fully consolidated from the date on which control is transferred to the Company. They are de-consolidated from the date that control ceases. All intercompany transactions have been eliminated. 3.2. Foreign currency translation Functional and presentation currency Items included in the financial statements of each of the Group entities are measured using the currency of the primary economic environment in which the entity operates (“the functional currency”). The consolidated financial statements are presented in US dollars (“USD” or “Dollars”), which is the Company’s functional and Group’s presentation currency. Transactions and balances Foreign currency transactions are translated into the functional currency using the exchange rates prevailing at the dates of the transactions. Foreign exchange gains and losses resulting from the settlement of such transactions and from the translation at year-end exchange rates of monetary assets and liabilities denominated in foreign currencies are recognized in Consolidated Statement of Operation. All foreign exchange gains and losses are presented in the Consolidated Statement of Operation within “Exchange differences”. Group companies The results and financial position of all the Group entities that have a functional currency different from the presentation currency are translated into the presentation currency as follows: (i) assets and liabilities for each balance sheet presented are translated at the closing rate at the date of that balance sheet; (ii) income and expenses for each Consolidated Statement of Operation are translated at monthly average exchange rates; and (iii) all resulting exchange differences are recognized in other comprehensive loss, under “Cumulative translation adjustments”. 3.3. Cash and cash equivalents Cash and cash equivalents includes cash on hand, deposits held at call with external financial institutions and other short-term highly liquid investments with original maturities to the Company of three months or less. They are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Any bank overdrafts are not netted against cash and cash equivalents but are shown as part of current liabilities on the Consolidated Balance Sheet. 3.4. Inventory The Company assessed its accounting policy for inventory costs, with the Company’s submission of its biologics license application (“BLA”) to the U.S. Food and Drug Administration (“FDA”) for Lonca for the treatment of relapsed or refractory diffuse large B-cell lymphoma (“DLBCL”). The Company believes that capitalization of inventory costs associated with certain products prior to regulatory approval of such products, or for inventory produced in new production facilities, is appropriate when management considers it highly probable that pre-approval inventory costs will be recoverable through future sales of the drug product. The determination to capitalize is based on the particular facts and circumstances relating to the expected regulatory approval of the product or production facility being considered and, accordingly, the time frame within which the determination is made varies from product to product. The assessment of whether or not the product is considered highly probable to be saleable will be made on a quarterly basis and includes, but is not limited to, how far a particular product or facility has progressed along the approval process, any known safety or efficacy concerns, potential labeling restrictions and other impediments. As of December 31, 2020, the Company believes it is highly probable that it will receive regulatory approval for Lonca. Accordingly, such costs incurred to manufacture pre-approved product would qualify to be capitalized as inventory. However, the Company has written-down such inventory costs incurred related to the manufacture of Lonca to a net realizable value of zero. The impairment charge has been recorded as research and development expense because of the inherent risks associated with the development of a product candidate, uncertainty about the regulatory approval process, including the expected dating of Lonca at the time of launch, as well as the timing of the associated commercial launch and market size for the drug candidate, and lack of history for the Company’s ability to obtain regulatory approval for drug candidates. The Company anticipates that it will reverse impairments resulting from the write-down of its inventory to a net realizable value of zero upon receiving regulatory approval of Lonca based on a number of factors including the existence of inventory on hand and estimated demand as well as the expiration of such product. 3.5. Property, plant and equipment All property, plant and equipment is stated at historical cost less accumulated depreciation. Historical cost includes expenditure that is directly attributable to the acquisition of the items. Depreciation is calculated using the straight-line method to reduce the cost of each asset to its residual value over its estimated useful life, as follows: Leasehold improvements 3 to 10 years Laboratory equipment 5 years Office equipment 5 years Hardware 3 years See note 14, “Property, plant and equipment” for further information. 3.6. Intangible assets Licenses Licenses acquired are capitalized as intangible assets at historical cost. Licenses with definite-useful lives are amortized over their useful lives, which are determined on a basis of the expected pattern of consumption of the expected future economic benefits embodied in the licenses and which therefore commence only once the necessary regulatory and marketing approval has been received. Prior to regulatory and marketing approval, licenses are treated as indefinite-lived assets and not amortized. These licenses are tested annually for impairment in the last quarter of each fiscal year and more frequently if events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. Amortization and impairment of licenses Prior to regulatory and marketing approval, impairment of indefinite-lived licenses is charged to research and development expenses. Subsequent to regulatory and marketing approval, amortization of licenses will be charged to cost of goods sold. See note 16, “Intangible assets” for further information. 3.7. Investments in joint ventures A joint venture is a joint arrangement whereby the parties that have joint control of the arrangement have rights to the net assets of the joint arrangement. Joint control is the contractually agreed sharing of control of an arrangement, which exists only when decisions about the relevant activities require unanimous consent of the parties sharing control. An investment in a joint venture is accounted for using the equity method from the date on which the investee becomes a joint venture. Under the equity method, an investment in a joint venture is recognized initially in the Consolidated Balance Sheet at cost and adjusted thereafter to recognize the Company’s share of the profit or loss, other comprehensive income or loss of the joint venture, distributions from the joint venture and other adjustments to the Company’s proportionate interest in the joint venture. The Company’s initial investment is recorded as an Interest in joint venture in the Consolidated Balance Sheet. The Company’s proportionate share of net income or losses of equity investments is included within Share of results with joint venture in the Consolidated Statement of Operation. The Company’s carrying value of its investment in a joint venture increases or decreases in relation to the Company’s proportionate share of comprehensive income or loss of the joint venture. When the Company’s share of losses of a joint venture exceeds the Company’s interest in that joint venture less the carrying value of the deferred gain described below, the Company ceases to recognize its share of further losses. Additional losses are recognized only to the extent that the Company has incurred legal or constructive obligations or made payments on behalf of the joint venture. In connection with the Company’s initial investment, the gain resulting from the transaction was only recognized to the extent of the unrelated investors’ equity interest in the joint venture, which resulted in a deferred gain for a portion of the Company’s initial investment. The Company will begin to recognize the deferred gain upon the commercialization of any or all the licensed intellectual property by the joint venture. The deferred gain will be recognized over the estimated commercialization period in which a licensed product is developed and approved using a systematic approach that approximates the pattern of consumption of the licensed intellectual property by the joint venture. Investments accounted for under the equity method are assessed for potential impairment on a regular basis based on qualitative factors. 3.8. Impairment of non-financial assets Non-financial assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. An impairment loss is recognized for the amount by which the asset's carrying amount exceeds its recoverable amount. The recoverable amount is the higher of an asset's fair value less costs of disposal and value in use. In assessing value in use, the estimated future cash flows, adjusted for the risks specific to each asset, are discounted to their present value using a discount rate that reflects current market assessments of the time value of money and the general risks affecting the pharmaceutical industry. For the purpose of impairment testing, assets are grouped together into the smallest group of assets that generate cash inflows from continuing use that are largely independent of the cash flows of other assets (“cash-generating units”). Impairment losses are recognized in the Consolidated Statement of Operation. Prior impairments of non-financial assets are reviewed for possible reversal of the impairment at each reporting date. 3.9. Employee benefits Employee Benefit Programs Group companies operate defined benefit and defined contribution pension schemes in accordance with the local conditions and practices in the countries in which they operate. The defined benefit schemes are generally funded through payments to insurance companies or trustee-administered funds, determined by periodic actuarial calculations. A defined contribution plan is a pension plan under which the Group pays fixed contributions into a separate entity (a fund) and has no legal or constructive obligations to pay further contributions if the fund does not hold sufficient assets to pay all employees the benefits relating to employee service in the current and prior periods. A defined benefit plan is a pension plan that is not a defined contribution plan. Typically, defined benefit plans define an amount of pension benefit that an employee will receive on retirement, usually dependent on one or more factors such as age, years of service and compensation. However, as is the case with many Swiss pension plans, although the amount of ultimate pension benefit is not defined, certain legal obligations of the plan nevertheless create constructive obligations on the employer to pay further contributions to fund an eventual deficit. This results in the plan being accounted for as a defined benefit plan. The liability recognized in the balance sheet in respect of defined benefit pension plans is the present value of the defined benefit obligation at the end of the reporting period less the fair value of plan assets. The defined benefit obligation is calculated annually by independent actuaries using the projected unit credit method. The present value of the defined benefit obligation is determined by discounting the estimated future cash outflows using interest rates of high-quality corporate bonds that are denominated in the currency in which the benefits will be paid, and that have terms to maturity that approximate the terms of the related pension obligation. The current service cost of the defined benefit plan, recognized in the Consolidated Statement of Operation in employee benefit expenses, except where included in the cost of an asset, reflects the increase in the defined benefit obligation resulting from employee service in the current year. Past service costs, resulting from a plan amendment or curtailment, are recognized immediately in the Consolidated Statement of Operation. The net interest cost is calculated by applying the discount rate to the net balance of the present value of the defined benefit obligation and the fair value of plan assets. This cost is included in employee benefit expenses in the Consolidated Statement of Operation. Actuarial gains and losses arising from experience adjustments and changes in actuarial assumptions are charged or credited to equity within the Consolidated Statement of Other Comprehensive Loss in the period in which they arise. For defined contribution plans, the company pays contributions to publicly or privately administered pension insurance plans on a mandatory, contractual or voluntary basis. Once the contributions have been paid, the company has no further payment obligations. The contributions are recognized as employee benefit expenses in the Consolidated Statement of Operation. Prepaid contributions are recognized as an asset to the extent that a cash refund or a reduction in the future payments is available. See note 20, “Pension obligations” for further information. Share-based compensation expense The fair value of shares or options granted, respectively, under share purchase or share option plans is recognized as an employee share-based compensation expense with a corresponding increase in equity. The total amount to be expensed is determined by reference to the fair value of the shares or options granted: – including any market performance conditions; – excluding the impact of any service and non-market performance vesting conditions; and – including the impact of any non-vesting conditions. The total expense is recognized over the vesting period, which is the period over which all of the specified vesting conditions are to be satisfied. At the end of each period, the entity revises its estimate of the number of options that are expected to vest based on the non-market vesting and service conditions. It recognizes the impact of the revision to original estimate, if any, within the Consolidated Statement of Operation, with a corresponding adjustment to equity. The proceeds received upon the exercise of options are net of any directly attributable transaction costs and are credited directly to equity. See note 22, “Share-based compensation expense” for further information. 3.10. Share capital and share premium Share capital The Company has issued one class of common shares, which is classified as equity (see note 23, “Share Capital”). Share premium Amounts of contribution in excess of par value are accounted for as share premium. Share premium also arises from additional capital contributions from shareholders. Incremental costs directly attributable to equity transactions such as the issue of new capital shares are shown in equity as a deduction, net of tax, from the proceeds within share premium. Transaction costs that relate to equity and non-equity transactions are allocated to those transactions using a basis of allocation that is rational and a consistent methodology with previous transactions. 3.11. Treasury shares Treasury shares are recognized at acquisition cost and deducted from shareholders’ equity at the time of acquisition, until they are cancelled. Where such shares are subsequently sold, any consideration received is included in shareholders’ equity. 3.12. Leases This policy concerns instances where a Group company is the lessee. Leases are recognized as a right-of-use asset and a corresponding liability at the date at which the leased asset is available for use by the group. Each lease payment is allocated between the liability and the finance cost. The finance cost is charged to the Consolidated Statement of Operation over the lease period so as to produce a constant periodic rate of interest on the remaining balance of the liability for each period. The right-of-use asset is depreciated over the shorter of the asset’s useful life and the lease term on a straight-line basis. The lease payments are discounted using the interest rate implicit in the lease. If that rate cannot be determined, the lessee’s incremental borrowing rate is used, being the rate that the lessee would have to pay to borrow the funds necessary to obtain an asset of similar value in a similar economic environment with similar terms and conditions. Right-of-use assets are measured at cost comprising the following: – the amount of the initial measurement of lease liability; – any lease payments made at or before the commencement date less any lease incentives received; – any initial direct costs, and – restoration costs. The lease term is considered to be the non-cancellable period of a lease, together with both: – periods covered by an option to extend the lease if the Company is reasonably certain to exercise that option; and – periods covered by an option to terminate the lease if the Company is reasonably certain not to exercise that option. Assumptions as to whether the Company is reasonably likely to exercise any extension or termination options have been individually assessed based on the Company’s plans. The policy of recognizing right-of-use assets and lease liabilities is not applied to short-term (under 12 months) or low value leases. For deferred tax purposes, the Group considers the net effect of temporary differences arising from the right-of-use asset and the lease liabilities. In 2018 and prior years, leases in which a significant portion of the risks and rewards of ownership are retained by the lessor were classified as operating leases. Payments made under operating leases (net of any incentives received from the lessor) were charged to the Consolidated Statement of Operation on a straight-line basis over the period of the lease. 3.13. Convertible loans The Company entered into a USD 115.0 million Facility Agreement (the “Facility Agreement”) (see note 21, “Convertible loans”) on April 24, 2020, pursuant to which the counterparty agreed to extend senior secured convertible term loans to the Company in two separate disbursements: (i) an initial disbursement of convertible loans in the amount of USD 65.0 million upon the completion of the IPO, and satisfaction of certain other conditions (the “first tranche”) and (ii) a subsequent disbursement of convertible loans in the amount of USD 50.0 million upon the receipt of regulatory approval for Lonca, and satisfaction of certain other conditions (the “second tranche”). Accounting for the first tranche On May 19, 2020, the Company received convertible loans in the amount of USD 65.0 million upon completion of the IPO. These convertible loans have been recognized as a hybrid financial instrument and accounted for as two separate components: (i) a loan and (ii) an embedded conversion option derivative. (i) The embedded conversion option derivative was initially measured at fair value and is subsequently remeasured to fair value at each reporting date. Under IAS 32, this derivative could have been classified as a component of equity only if in all cases the contract would be settled by the Company delivering a fixed number of its own equity instruments in exchange for a fixed amount of cash or debt redemption. However, the agreement foresees, in the event of a major transaction, the payment of “make-whole” amounts that would have to be computed in the light of the circumstances and are therefore not fixed. As a result, the derivative is presented in the balance sheet as a liability and classified as non-equity in accordance with IFRS 9 and IAS 32. Changes in the fair value (gains or losses) of the derivative at the end of each period are recorded in the Consolidated Statement of Operation. (ii) The convertible loan’s initial fair value is the residual amount of the consideration received, net of attributable costs, after separating out the fair value of the embedded conversion option derivative. The loan is subsequently measured at its amortized cost in accordance with IFRS 9. It is presented as a financial liability in the Consolidated Balance Sheet. Expenses and fees payable upon the issuance of the first tranche of convertible loans were allocated pro rata to the above two components. The share of expenses allocated to the embedded conversion option derivative was charged directly to the Consolidated Statement of Operation, while the share of expenses allocated to the residual convertible loan was deducted from the loan. Accounting for the second tranche The Company is obligated to draw down the second tranche in the amount of USD 50.0 million upon receipt of regulatory approval for Lonca. However, the second tranche will automatically terminate if the Company has not received the regulatory approval on or prior to December 31, 2021. This obligation has been accounted for as a derivative, and presented in the Consolidated Balance Sheet as a financial liability. Changes in the fair value (gains or losses) of the derivative at the end of each period are recorded in the Consolidated Statement of Operation. 3.14. Revenue recognition To date, the Company has not generated any revenue from the sale of its product candidates. Revenue is measured at the fair value of the consideration received or receivable for the sale of services in the ordinary course of the Group’s activities. Revenue is shown net of value-added tax, rebates and discounts and after eliminating sales within the Group. The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company applies the five-step model to contracts only when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract, determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Performance obligation satisfied to the state of completion - deferred contract revenue amortization When the outcome of a transaction involving the rendering of services can be estimated reliably, revenue is recognized according to the stage of completion of the transaction at the end of the period using the cost input method. Under this method, revenue is recognized in the accounting periods in which the services are rendered. The recognition of revenue on this basis provides full information on the extent of service activity and performance during a period. To be able to estimate the outcome of a transaction reliably, the entity must be able to make a reliable estimate of total transaction revenue, the stage of completion and the costs to complete the transaction. The stage of completion is determined as the proportion of the transaction costs incurred for services rendered to date compared to the estimated total transaction costs. 3.15. Research and development (“R&D”) expenses Research expenditure is recognized in expense in the year in which it is incurred. Internal development expenditure is capitalized only if it meets the recognition criteria of IAS 38 “Intangible Assets”. Where regulatory and other uncertainties are such that the criteria are not met, which is almost invariably the case prior to approval of the drug by the relevant regulatory authority, the expenditure is recognized in the Consolidated Statement of Operation. When certain criteria are met, the Company may capitalize and amortize on a straight-line basis over its estimated useful life, internal development expenditures. To date, the Company has not capitalized any R&D expenses. 3.16. Selling and marketing (“S&M”) expenses S&M expense is expensed when incurred and include employee expenses (including share-based compensation expense) for commercial employees, external costs related to commercialization (including professional fees, communication costs and IT costs and travel expenses). To date, depreciation expense and facility expense has not been material. 3.17. General and administrative (“G&A”) expenses G&A expense is expensed when incurred and include employee expenses (including share-based compensation expense) for G&A employees, external costs (including in particular professional fees, communications costs and IT costs, facility expenses and travel expenses), G&A costs charged by related parties (including telecommunications costs), depreciation of property, plant and equipment, depreciation of right-of-use assets and amortization of intangible assets. 3.18. Current, deferred income tax and tax credit The tax expense for the period comprises current and deferred tax. Tax is recognized in the Consolidated Statement of Operation, except to the extent that it relates to items recognized in other comprehensive loss or directly in equity; in this case the related tax is recognized in other comprehensive loss or directly in equity, respectively. The current income tax charge is calculated on the basis of the tax laws enacted or substantively enacted at the balance sheet date in the countries where the Company and its subsidiaries operate and generate taxable income. Management periodically evaluates positions taken in tax returns with respect to situations in which applicable tax regulation is subject to interpretation. It establishes provisions where appropriate on the basis of amounts expected to be paid to the tax authorities. Taxes on income are accrued in the same periods as the revenues and expenses to which they relate. Current income tax assets and liabilities for the current period are measured at the amount expected to be recovered from or paid to the taxation authorities. Deferred income tax is recognized, using the liability method, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the Consolidated Financial Statements. However, deferred tax liabilities are not recognized if they arise from the initial recognition of goodwill. The deferred income tax is not accounted for if it arises from initial recognition of an asset or liability in a transaction other than a business combination that at the time of the transaction affects neither accounting nor taxable profit or loss. Deferred income tax is determined using tax rates (and laws) that have been enacted or substantively enacted by the balance sheet date and are expected to apply when the related deferred income tax asset is realized or the deferred income tax liability is settled. Deferred income tax assets are recognized only to the extent that it is probable that future taxable profit will be available against which the temporary differences or the unused tax losses can be utilized. Deferred income tax assets from tax credit carryforwards are recognized to the extent that the national tax authority confirms the eligibility of such a claim and that the realization of the related tax benefit through future taxable profits is probable. Deferred income tax assets and liabilities are offset when there is a legally enforceable right to offset current tax assets against current tax liabilities and when the deferred income tax assets and liabilities relate to income taxes levied by the same taxation authority on either the same taxable entity or different taxable entities where there is an intention to settle the balances on a net basis. 3.19. Segment reporting The Company is managed and operated as one business. A single management team that reports to the chief executive officer comprehensively manages the entire business. Accordingly, the Company views its business and manages its operations as one operating segment. Revenue is attributable to the Company’s country of domicile, Switzerland. The Company has locations in three regions: Switzerland, the United Kingdom and the United States. An analysis of non-current assets by geographic region is presented in note 13, “Non-current assets by geographic area”. 3.20. Loss per share Basic loss per share is calculated by dividing the net loss attributable to shareholders by the weighted average number of common shares in issue during the year, excluding common shares owned by the Company and held as treasury shares. See note 27, “Loss per share.”

New and amended IFRS standards

New and amended IFRS standards	12 Months Ended
	Dec. 31, 2020
Accounting Policies, Changes, Accounting Estimates And Errors [Abstract]
New and amended IFRS standards	New and amended IFRS standards (i) New and amended IFRS standards There are no new IFRS standards, amendments to standards or interpretations that are mandatory for the financial year beginning on January 1, 2020, that are relevant to the Group and that have had any impact in the interim periods. New standards, amendments to standards and interpretations that are not yet effective, which have been deemed by the Group as currently not relevant, and hence are not listed here. (ii) Recently adopted IFRS standards IFRS 16 “Leases” has been adopted by the Group from January 1, 2019. Under IAS 17, lessees were required to make a distinction between a finance lease (on balance sheet) and an operating lease (off balance sheet). IFRS 16 now requires lessees to recognize an asset, being the right to use the leased item, and a financial liability, reflecting future lease payments, for virtually all lease contracts, though there is an optional exemption for certain short-term leases and leases of low-value assets. The Group has applied the modified retrospective approach, which requires the recognition of the cumulative effect of initially applying IFRS 16 as of January 1, 2019 to accumulated losses without restating prior years. Since the Group recognized the right-of-use assets at an amount equal to the lease liabilities there was no impact on accumulated losses. The new accounting policy for leases is set out in note 3.12, “Leases”. The Group has elected to apply the following practical expedients in adopting IFRS 16: (i) not to recognize right-of-use assets and lease liabilities for leases of low value, (ii) to apply hindsight in determining the lease term for contracts which contain certain options to extend or terminate the lease, (iii) to account for each lease component and any non-lease components as a single lease component, (iv) to rely on its assessment of whether leases were onerous by applying IAS 37 Provisions, Contingent Liabilities and Contingent Assets immediately before the date of application, and (v) to exclude initial direct costs for the measurement of the right-of-use asset at the date of initial application. The Group’s weighted average incremental borrowing rate calculated as of January 1, 2019 was 2.66%. The following table reconciles the Group's operating lease obligations at December 31, 2018, as computed under the Group's previous accounting policy disclosed above in note 3.12, “Leases”, with the lease obligations recognized on initial application of IFRS 16 at January 1, 2019. (in KUSD) Operating lease commitments at December 31, 2018 4,378 Discounted at the incremental borrowing rate as at January 1, 2019 3,976 Short-term leases recognized on a straight-line basis as expenses (15) Low-value leases recognized on a straight-line basis as expenses — Extension options reasonably certain to be exercised 1,462 Lease obligations recognized at January 1, 2019 5,423 Of which are: Lease liabilities (short-term) 924 Lease liabilities (long-term) 4,499 In accordance with the adoption of IFRS 16 “Leases” as of January 1, 2019, the Group recorded at initial recognition a non-cash KUSD 5,423 right-of-use asset and corresponding lease liability. The Group’s Consolidated Statement of Operation for the year ended December 31, 2019 was impacted by an increase in depreciation of right-of-use leased assets of KUSD 1,064 and a reduction in operating lease expenses of KUSD 1,002. The increase in interest expense was KUSD 141. During the same periods, the Group’s cash flow statement was impacted by a shift of KUSD 1,143 from cash generated from operations to net cash used in financing activities. Overall, IFRS 16 was cash neutral for the Group. See note 15, “Leases.”

Financial risk management

Financial risk management	12 Months Ended
	Dec. 31, 2020
Financial Instruments [Abstract]
Financial risk management	Financial risk management 5.1 Financial risk factors Management and the Board of Directors regularly reviews the Group cash forecast and related foreign exchange risk. It also performs the risk assessment, defines any necessary measures and ensures the monitoring of the internal control system. The Group does not use derivative financial instruments to hedge these exposures. Foreign exchange risk The Group operates internationally and is exposed to foreign exchange risk arising from various currency exposures, primarily with respect to British pounds, Euros and Swiss francs. Transaction exposure arises because the amount of local currency paid or received in transactions denominated in foreign currencies may vary due to changes in exchange rates. Foreign exchange risk arises from: – forecast costs denominated in a currency other than the entity’s functional currency; – recognized assets and liabilities denominated in a currency other than the entity's functional currency; and – net investments in foreign operations. Management believes that foreign exchange risk is minimal, as the Company pays invoices mainly in USD and holds cash principally in USD. The Group's cash and cash equivalents are denominated in the following currencies: 2020 2020 2019 2019 December 31 in KL/C (1) in KUSD in KL/C (1) in KUSD In USD 435,750 435,750 109,939 109,939 In CHF 376 426 457 472 In GBP 2,096 2,861 3,529 4,654 In EUR 129 158 433 486 439,195 115,551 _______________ (1) Thousands Local Currencies The Group has certain investments in foreign operations whose net assets are exposed to foreign currency translation risk. Currency exposure arising from these net assets of the Group’s foreign operations is managed primarily through purchasing goods and services denominated in the relevant foreign currencies. At December 31, 2020, if the USD had weakened / strengthened by 10% against the CHF with all other variables held constant, the pre-tax loss for the year would have been KUSD 1,013 higher / lower, mainly as a result of foreign exchange losses / gains on translation of CHF-denominated net monetary liabilities (2019: KUSD 201 higher / lower on net monetary assets). At December 31, 2020, if the USD had weakened / strengthened by 10% against the EUR with all other variables held constant, the pre-tax loss for the year would have been KUSD 214 higher / lower, mainly as a result of foreign exchange losses / gains on translation of EUR-denominated net monetary liabilities (2019: KUSD 95 higher / lower on net monetary assets). At December 31, 2020, if the USD had weakened / strengthened by 10% against the GBP with all other variables held constant, the pre-tax loss for the year would have been KUSD 323 higher / lower, mainly as a result of foreign exchange losses / gains on translation of GBP-denominated net monetary liabilities (2019: KUSD 290 higher / lower), and the gain on currency translation differences credited directly to equity and arising on the translation of the net assets of ADCT UK would have been KUSD 439 higher / lower (2019: KUSD 320 higher / lower on net monetary assets). Interest rate risk Interest rate risk arises from movements in interest rates which could have adverse effects on the Group's net income or financial position. Changes in interest rates cause variations in interest income and expenses on interest-bearing assets and liabilities, and on the value of the net defined benefit pension obligation. See note 5.3, “Fair value estimation” for a further discussion on the risk free rate and implied bond yield sensitivity analysis used in determining the fair value of the embedded derivative and derivative associated with the Company’s convertible loans. Credit risk Credit risk is the risk that a counterparty will not meet its obligations under a financial instrument or customer contract, leading to a financial loss. The Group is exposed to credit risk from its operating activities and from its financing activities including deposits with banks and other financial institutions (see note 17b, “Credit quality of financial assets”). The Group’s cash and cash equivalents accounts are maintained with well established, highly rated financial institutions. The Company’s wholly-owned subsidiaries are solvent, are managed on a cost-plus service provider basis, and are supported by the Company as the parent. Liquidity risk Liquidity risk is the risk that the Group may not be able to generate sufficient cash resources to settle its obligations in full as they fall due or can do so only on terms that are materially disadvantageous. Prudent liquidity risk management implies maintaining sufficient cash to cover working capital requirements. Cash is monitored by the Group management. Funding and liquidity risks are reviewed regularly by management and the Board of Directors. The Board of Directors reviews the Group’s ongoing liquidity risks quarterly as part of the financial review process and on an ad hoc basis as necessary. To date, the Company has funded its capital requirements through capital raises, including the issuance of the Company’s common shares and the issuance of convertible loans (see note 21, “Convertible loans) or partnering of its programs. The table below analyses the Group's financial liabilities into relevant maturity groupings based on the remaining period at the balance sheet date to the contractual maturity date. (in KUSD) Note Less than 1-3 3-5 More than Trade accounts payable 5,279 — — — Lease liabilities, contractual rent 15 1,050 1,047 642 903 Convertible loan, interest and exit fee 21 3,921 7,842 7,703 — Convertible loan, principal (1) 21 — — 65,000 — At December 31, 2020 10,250 8,889 73,345 903 Trade accounts payable 3,329 — — — Lease liabilities, contractual rent 15 1,246 1,859 2,265 — At December 31, 2019 4,575 1,859 2,265 — (1) Amount represents the principal amount of the convertible loan due May 2025 associated with the first tranche of the Facility Agreement. See note 21, “Convertible loans”. In addition, the Facility Agreement contains a second tranche of USD 50.0 million that the Company is obligated to draw down upon the receipt of regulatory approval of Lonca. While the Company believes that it is highly probable that regulatory approval will be obtained, such amount has not been included in the table above as the amount has not been drawn down as of December 31, 2020. 5.2 Capital management The Group considers equity as equivalent to the IFRS equity on the balance sheet (including share capital, share premium and all other equity reserves attributable to the owners of the Company). Other than its lease liabilities, the Group’s only interest-bearing debt relates to the issuance of convertible loans (see note 21, “Convertible loans”). The primary objective of the Group's capital management is to maximize shareholder value. Management and the Board of Directors regularly reviews its shareholder return strategy. For the foreseeable future, management and the Board of Directors will maintain a capital structure that supports the Group's strategic objectives through managing funding and liquidity risks and optimizing shareholder return. The Company is a late clinical-stage biotechnology company with product candidates still at pre-clinical and clinical stages of development. During the fourth quarter of 2020, the FDA accepted the Company’s BLA for Lonca for the treatment of relapsed or refractory DLBCL and granted priority review status. The FDA set a Prescription Drug User Free Act (“PDUFA”) target date of May 21, 2021. Even if the FDA approves Lonca for commercial sale, the Company does not expect to have significant revenues in 2021. It intends to continue to explore financing opportunities either through the equity or debt markets as well as through cooperation and collaboration with pharmaceutical and biotechnology partners – potentially along the value chain from research alliances through co-development to commercialization. As explained in note 2 (iii), “Going concern basis”, management believes that the Company has sufficient financial resources available to meet all of its obligations for at least the twelve months from the issuance of these consolidated financial statements without additional capital becoming available. 5.3 Fair value estimation At December 31, 2020, the carrying amount is a reasonable approximation of fair value for the following financial assets and liabilities: – Cash and cash equivalents – Trade accounts payable In 2020, there were no significant changes in the business or economic circumstances that affect the fair value of the Group's financial assets and financial liabilities with the exception of the Company entering into the Facility Agreement. See note 21, “Convertible loans”. The Company received convertible loans in the amount of USD 65.0 million. These convertible loans have been recognized as a hybrid financial instrument and accounted for as two separate components: (i) a loan and (ii) an embedded conversion option derivative. The Company is obligated to draw down the second tranche in the amount of USD 50.0 million upon receipt of regulatory approval for Lonca. If the Company has not received the regulatory approval on or prior to December 31, 2021, the second tranche will automatically terminate on such date. This obligation has been accounted for as a derivative. Each quarter, the Company marks-to-market this derivative and the embedded conversion option derivative with changes in the fair value (gains or losses) of the derivatives recorded in the Consolidated Statement of Operation. Fair values must be estimated on an ongoing basis with regard to awards under the ADC Therapeutics SA 2019 Equity Incentive Plan (the “2019 Equity Incentive Plan”), with regard to the convertible loan conversion option derivative related to the first tranche of the convertible loans and with regard to the derivative arising from the obligation related to the second tranche of the convertible loans. The approach to valuation follows the grant date fair value principle and the key input factors are described for the share-based compensation awards in note 22, “Share-based compensation” and for the convertible loan derivatives in note 21, “Convertible loans”. Commonly accepted pricing models (Hull and Goldman Sachs) have been used to calculate the fair value of the convertible loan derivatives. The valuation of the embedded derivative in the first tranche and derivative relating to the second tranche are classified as pertaining to level 3 of the valuation hierarchy set out below. The different levels of the valuation hierarchy have been defined as follows: a. Level 1: quoted prices (unadjusted) in active markets for identical assets or liabilities; b. Level 2: inputs other than quoted prices that are observable for the asset or liability, either directly (for example, as prices) or indirectly (for example, derived from prices); c. Level 3: inputs for the asset or liability that are not based on observable market data. There were no transfers between the respective levels during the period. The embedded derivative conversion feature and the derivative associated with the first and second tranche of the Company’s convertible loans (see note 21, “Convertible loans”), respectively, are re-measured to fair value at each reporting date. The Company utilizes a risk free rate, an implied bond yield and a selected volatility in determining the fair value of its embedded derivative and derivative. A hypothetical 10% increase (decrease) in the risk free rate as of December 31, 2020 would have increased (decreased) the derivative values associated with the first and second tranche of our convertible loans by KUSD 5 (KUSD 5) and KUSD 4 (KUSD 4), respectively. A hypothetical 10% increase (decrease) in the implied bond yield as of December 31, 2020 would have increased (decreased) the derivative value associated with the first tranche of our convertible loans by KUSD 2,088 and (KUSD 898) and (decreased) increased the derivative value associated with the second tranche of our convertible loans by (KUSD 846) and KUSD 875. A hypothetical 10% increase (decrease) in the selected volatility as of December 31, 2020 would have increased (decreased) the derivative value associated with the first tranche of our convertible loans by KUSD 2,043 (KUSD 248) and decreased (increased) the derivative value associated with the second tranche of our convertible loans by (KUSD 52) and KUSD 234.

Critical accounting estimate an

Critical accounting estimate and judgements	12 Months Ended
	Dec. 31, 2020
Accounting Policies, Changes In Accounting Estimates And Errors [Abstract]
Critical accounting estimate and judgements	Critical accounting estimates and judgements Estimates and judgements are continually evaluated and are based on historical experience and other factors, including expectations of future events that are believed to be reasonable under the circumstances. The estimates, assumptions and judgements that have significantly affected reported results or that have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year are addressed below. Licenses The Company enters into collaboration, license and sublicense agreements with third parties, which grant the Company the right to use their antibodies with the Company's licensed warhead and linker technology to develop new ADCs for anti-cancer treatments. The license fees (upfront fees, signature fees, milestone payments) paid by the Company under the agreements are capitalized as intangible assets. The Company considers that those licenses have an indefinite life until regulatory and marketing approval is obtained. Once obtained, the asset will be treated as a finite intangible asset and amortization will commence. The license costs capitalized were KUSD 1,923 and KUSD 1,731 for the years 2020 and 2019, respectively. The intangible assets are tested annually for impairment and more frequently if events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. An impairment loss is recognized for the amount by which the asset's carrying amount exceeds its recoverable amount (higher of an asset's fair value less costs of disposal and value in use). Impairment losses are recognized in the Consolidated Statement of Operation. Testing for impairment inevitably involves the application of judgement. In 2020 and 2018, in relation to the termination of one of the Company's programs in each year, an impairment charge of KUSD 216 and KUSD 227, respectively (corresponding to the entire carrying amount of the capitalized license) was recognized and charged to research and development expenses in the Consolidated Statement of Operation. The Company performed its review for 2019 and concluded no impairment was required. See note 16, “Intangible assets”. Convertible loans The Company entered into the Facility Agreement, pursuant to which the counterparty agreed to extend senior secured convertible term loans to the Company in two separate tranches. The Company received the first tranche upon the completion of the IPO. The first tranche has been recognized as a hybrid financial instrument and accounted for as two separate components: (i) a loan and (ii) an embedded conversion option derivative. The Company is obligated to draw down on the second tranche upon receipt of regulatory approval for Lonca. If the Company has not received the regulatory approval on or prior to December 31, 2021, the second tranche will automatically terminate on such date. The second tranche has been accounted for as a derivative. In determining the value of the loan and embedded derivative associated with the first tranche as well as the derivative associated with the second tranche, the Company utilized significant estimates and judgements. In particular, significant judgement was required in deciding whether the conversion option derivative embedded in the notes was of a liability or equity nature, in selecting the appropriate models to value the derivatives arising from the first and second tranches of the convertible notes and in identifying the appropriate key assumptions as inputs to the selected models. Details of the models and assumptions are set out in note 21, “Convertible loans”. Share-based compensation expense The details of the ADC Therapeutics Incentive Plan 2014 (as amended and restated as of October 1, 2015, the “Incentive Plan 2014”), the Share Purchase Plan 2016 and the 2019 Equity Incentive Plan are explained in note 22, “Share-based compensation expense”. Prior to the Company’s IPO, the determination of the fair value of awards involved the application of an adjusted form of the Black-Scholes option pricing model that took into account the strike price, term of the award, impact of dilution (where material), share price at grant date and expected price volatility of the underlying share, expected dividend yield, risk free interest rate for the term of the award and correlations and volatilities of the shares of peer group companies. In addition, for awards granted on and subsequent to July 1, 2019 through the IPO date, the fair value of grants was based on a probability-weighted expected returns method that took into account both the value derived by using an adjusted form of the Black-Scholes option pricing model and a discounted estimate of the price that may have been achieved in a future transaction. This method entailed further significant judgement, both in estimating a transaction price and in estimating the probabilities of different outcomes. The adjusted form of the Black-Scholes option pricing model used to derive a value for the common share price at grant date derived the implied equity value for one type of equity security from a contemporaneous transaction involving another type of security and considered the timing, amount, liquidation preferences and dividend rights of issues of preference shares. After the Company’s IPO, the determination of the fair value of awards involves the application of the Black-Scholes option pricing model for the Company’s option equity awards, which utilizes certain assumptions including expected volatility, expected life and risk-free interest rate. In addition, the exercise price per share option is set by the Company at the fair market value of the underlying common

Contract revenue and contract l

Contract revenue and contract liability	12 Months Ended
	Dec. 31, 2020
Revenue From Contracts With Customers [Abstract]
Contract revenue and contract liability	Contract revenue and contract liabilityContract revenue represents the amortization of upfront payments received under license and collaboration contracts in order to finance the research and development that is the subject of those contracts as well as associated milestone payments. In 2013, the Company entered into a license and joint collaboration agreement which was subsequently discontinued in June 2019. As a result of the discontinuance of this joint development program, the remaining balance of the non-refundable upfront payment (consisting of deferred revenue and presented as a contract liability) received under the related license and collaboration agreement was recognized in the first half of 2019 as contract revenue, and no additional contracts giving rise to current contract revenue have been entered into by the Company. As such, the Company recognized revenue of KUSD 2,340 associated with the remaining balance of the non-refundable upfront payment for the year ended December 31, 2019. The Company recognized revenue of KUSD 1,140 for the year ended December 31, 2018. There was no deferred revenue as of December 31, 2020 and December 31, 2019.

Other income (expense)

Other income (expense)	12 Months Ended
	Dec. 31, 2020
Analysis of income and expense [abstract]
Other income (expense)	Other income (expense) Year Ended December 31, (in KUSD) Note 2020 2019 2018 Other income 584 1,655 — Convertible loans, derivatives, change in fair value (expense) 21 (45,411) — — Convertible loans, first tranche, derivative, transaction costs 21 (1,571) — — Share of results with joint venture 2 (viii) 24,368 — — Financial income 832 2,253 2,856 Financial expense (4,926) (156) — Exchange differences (loss) gain (576) (255) 213 Total other (expense) income (26,700) 3,497 3,069 Other income The Company recognizes as other income amounts received and receivable by its subsidiary, ADCT UK, under the United Kingdom’s Research and Development Expenditure Credit scheme (“UK R&D Credit Scheme”). During 2019, the Group recognized amounts received and receivable by ADCT UK for the first time under the UK R&D Expenditure Credit Scheme. The grants represent 12% of eligible expenditure (11% for periods prior to 2018). Because of the strictness of the eligibility criteria for these credits, the Group did not recognize any income under this scheme until it had positive confirmation that initial claims had been approved for payment, which occurred in 2019. The claims are payable through the tax system, as a refund of corporation tax or of other taxes, including income tax and social security payments deducted at source from qualifying (research) employees’ payroll and VAT. The relevant amounts have been therefore presented net in the balance sheet. As the credit is independent of ADCT UK’s taxable profit, is clearly designed to incentivize companies to invest in R&D activities and is itself taxable income, the Group has recognized the income as government grants within other income and not as a credit to income tax expense. Financial income Our financial income decreased to KUSD 832 for year ended December 31, 2020 primarily due to lower amounts placed on short-term deposit and lower interest rates. Financial expense Financial expense primarily relates to interest on the convertible loans, calculated at the implied effective interest rate, from May 19, 2020. This expense is explained in note 21, “Convertible loans”. Exchange differences (loss) gain Due to our international operations, the Company is exposed to foreign exchange risk arising from various currency exposures, primarily with respect to British pounds, Euros and Swiss francs. Exchange differences represent income or (loss) based on changes in foreign currencies. Favorable or unfavorable changes in foreign currencies resulted in a loss of KUSD 576 and KUSD 255 and income of KUSD 213 for the years ended December 31, 2020, 2019 and 2018, respectively.

Employee expenses

Employee expenses	12 Months Ended
	Dec. 31, 2020
Analysis of income and expense [abstract]
Employee expenses	Employee expenses Year Ended December 31, (in KUSD) Note 2020 2019 2018 Wages, salaries and other costs 44,058 24,061 19,245 Social security costs 7,292 3,871 3,452 Share-based compensation expense 22 42,928 1,117 469 Defined benefit plan costs 20 966 462 535 Defined contribution plan costs 727 540 481 Employee expenses 95,971 30,051 24,182 Employee expenses increased from KUSD 30,051

Expenses by nature

Expenses by nature	12 Months Ended
	Dec. 31, 2020
Analysis of income and expense [abstract]
Expenses by nature	Expenses by nature The following table provides the Consolidated Statement of Operation classification of our expense by nature: Year Ended December 31, (in KUSD) Note 2020 2019 2018 R&D External costs (1) 97,768 82,621 99,067 Employee expenses (2) 9 44,264 24,916 19,246 R&D expense 142,032 107,537 118,313 S&M External costs 11,887 — — Employee expenses (2) 9 10,214 — — S&M expense 22,101 — — G&A External costs (1) 13,637 9,067 3,832 Employee expenses (2) 9 41,493 5,135 4,936 G&A expense 55,130 14,202 8,768 Total operating expense 219,263 121,739 127,081 (1) Includes depreciation expense; Depreciation expense for S&M was not material. (2) Includes share-based compensation expense The increase in R&D expense in the year ended December 31, 2020 was due to higher employee expenses related to an increased number of employees as the Company continues to advance clinical trials associated with its lead product candidates, which also contributed to an increase in share-based compensation expense. External costs increased primarily due to the advancement of the Company’s clinical trials associated with its lead product candidates. In addition, we recorded a charge for a milestone payment of USD 5.0 million associated with a collaboration agreement that was achieved during December 2020. The decrease in R&D expense in 2019 was primarily due to a lower chemistry, manufacturing and controls (“CMC”) costs as the clinical trials advance, partially offset by higher employee expense due to the increased number of employees necessary to advance the Company’s lead product candidates. S&M expense in the year ended December 31, 2020 related to the build-out of the commercial organization as the Company prepares for the anticipated launch of Lonca in 2021. During the year ended December 31, 2019, the Company incurred KUSD 158 of S&M expense

Income tax expense

Income tax expense	12 Months Ended
	Dec. 31, 2020
Income Taxes [Abstract]
Income tax expense	Income tax expense Year Ended December 31, (in KUSD) 2020 2019 2018 Current income taxes for the year 417 572 218 Current income taxes related to prior years (90) 10 6 Income tax expense 327 582 224 The Group's expected tax expense for each year is based on the applicable tax rate in each individual jurisdiction, which in 2020 ranged between 13.68% and 21.0% (2019: between 11% and 27%; 2018: between 11% and 27%) in the tax jurisdictions in which the Group operates. The weighted average tax rate applicable to the profits of the consolidated entities was 13.8% (2019: 11.5%; 2018: 11.3%). This increase is due to changes in the mix of the taxable results and the changes in tax rates of the individual group companies. The tax on the Group's net loss before tax differs from the theoretical amount that would arise using the weighted average applicable tax rate as follows: Year Ended December 31, (in KUSD) 2020 2019 2018 Loss before taxes 245,963 115,902 122,872 Tax calculated at tax domestic rates applicable to profits in the respective countries (33,319) (12,332) (13,321) Tax effects of: - Tax losses for which no deferred income tax asset was recognized 26,112 13,187 13,766 - Utilization of R&D tax credit (USA) (546) (436) (310) - Income not subject to tax / (expenses not deductible for tax purposes) 8,166 156 83 - Tax relating to prior years (90) 10 6 - Other 4 (3) — Income tax expense 327 582 224

Other current assets

Other current assets	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Other current assets	Other current assets (in KUSD) December 31, 2020 December 31, 2019 VAT receivable, net 453 471 Withholding tax receivable 991 626 Prepaid insurance 2,852 — Prepaid compensation 1,488 — Prepaid expenses - other 3,815 4,215 UK R&D expenditure credit receivable 1,246 891 Other 410 852 11,255 7,055 The increase of USD 4.2 million in other current assets is primarily due to an increase in prepaid insurance relating to Director and Officer insurance and prepaid compensation in the form of employment sign-on bonuses associated with the increase in headcount in 2020. For further information regarding the UK R&D Credit Scheme, please refer to note 8, “Other income and expense”. The maturity of other current assets is less than one year. The Company considers the counterparty risk as low. The Company believes the carrying amount of the aforementioned receivables is considered to approximate their fair value.

Non-current assets by geographi

Non-current assets by geographic area	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Non-current assets by geographic area	Non-current assets by geographic area (in KUSD) Country December 31, 2020 December 31, 2019 Switzerland 60,231 10,903 United Kingdom 1,132 2,032 United States 1,482 1,773 62,845 14,708 Non-current assets consist of property, plant and equipment, right-of-use assets, intangible assets and interest in joint venture. All intangible assets and the interest in joint venture are located in Switzerland.

Property, plant and equipment

Property, plant and equipment	12 Months Ended
	Dec. 31, 2020
Property, plant and equipment [abstract]
Property, plant and equipment	Property, plant and equipment (in KUSD) Leasehold Laboratory Office Hardware Construction in progress Total Cost January 1, 2019 514 939 597 497 — 2,547 Additions 17 131 93 118 — 359 Exchange difference 2 41 8 3 — 54 December 31, 2019 533 1,111 698 618 — 2,960 Additions 224 30 84 616 67 1,021 Disposals and scrapping (13) (178) (117) (367) — (675) Exchange difference 2 39 6 3 — 50 December 31, 2020 746 1,002 671 870 67 3,356 Accumulated depreciation January 1, 2019 (126) (310) (245) (326) — (1,007) Depreciation charge (82) (204) (149) (117) — (552) Exchange difference (1) (19) (3) (2) — (25) December 31, 2019 (209) (533) (397) (445) — (1,584) Depreciation charge (162) (207) (173) (232) — (774) Disposals and scrapping 13 178 117 367 — 675 Exchange difference (4) (32) (4) (4) — (44) December 31, 2020 (362) (594) (457) (314) — (1,727) Net book amount December 31, 2019 324 578 301 173 — 1,376 December 31, 2020 384 408 214 556 67 1,629 In 2020, the investments in tangible fixed assets relate to hardware due to the increased number of employees and certain leasehold improvements. During 2020, the Company wrote-off fully depreciated property, plant and equipment no longer in use. In 2019, the investments in tangible fixed assets relate mainly to investments in the UK laboratory and in hardware. Depreciation of property, plant and equipment has been charged to the following categories in the Consolidated Statement of Operation: Year Ended December 31, (in KUSD) 2020 2019 2018 R&D expense 589 407 330 G&A expense 185 145 158 774 552 488

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	Leases The following tables provide balance sheet classification related to leases: (in KUSD) December 31, 2020 December 31, 2019 Properties (offices) 3,071 4,820 Vehicles 58 78 Total right-of-use assets 3,129 4,898 (in KUSD) December 31, 2020 Three Months Ended December 31, 2019 Lease liabilities (short-term) 1,002 1,132 Lease liabilities (long-term) 2,465 3,899 Total lease liabilities 3,467 5,031 Prior to fiscal year 2019, all leases were classified as ‘operating leases’ under IAS 17 and were accordingly not recognized as assets and liabilities. In 2018, lease payments incurred for all non-cancellable operating leases were recorded in the Consolidated Statement of Operation in an amount of KUSD 869. As the Company continues to grow its operations, prepares for product commercialization and further develops its pipeline, it is looking to expand its facilities. During the third quarter of 2020, the Company concluded it was reasonably certain that it would modify the terms of various existing lease agreements in accordance with the underlying terms of the agreements, which would reduce the Company’s future minimum lease obligations. As a result, the Company reduced its Right of use assets and Leased liability, non-current by KUSD 583. (in KUSD) Right-of-Use Assets Properties (Offices) Vehicles Total Cost January 1, 2019 5,399 24 5,423 Additions 466 78 544 Disposals — (24) (24) Exchange difference 22 — 22 December 31, 2019 5,887 78 5,965 Modification of lease terms (583) — (583) Exchange difference 20 — 20 December 31, 2020 5,324 78 5,402 Accumulated depreciation January 1, 2019 — — — Depreciation charge (1,051) (13) (1,064) Disposals — 13 13 Exchange difference (16) — (16) December 31, 2019 (1,067) — (1,067) Depreciation charge (1,131) (20) (1,151) Exchange difference (55) — (55) December 31, 2020 (2,253) (20) (2,273) Net book amount December 31, 2019 4,820 78 4,898 December 31, 2020 3,071 58 3,129 Depreciation of right-of-use assets have been charged to the following categories in the Consolidated Statement of Operation: For the Years Ended (in KUSD) 2020 2019 R&D expenses 915 837 G&A expenses 236 227 1,151 1,064 (in KUSD) Lease liabilities Properties (Offices) Vehicles Total January 1, 2019 5,399 24 5,423 Additions 466 78 544 Disposals — (12) (12) Cash outflow (including interest) (1,130) (13) (1,143) Interest 140 1 141 Exchange difference 78 — 78 December 31, 2019 4,953 78 5,031 Additions — — — Modification of lease terms (583) — (583) Cash outflow (including interest) (1,227) (22) (1,249) Interest 102 3 105 Exchange difference 157 6 163 December 31, 2020 3,402 65 3,467 December 31, 2019 Lease liabilities (short-term) 1,114 18 1,132 Lease liabilities (long-term) 3,839 60 3,899 Total lease liabilities 4,953 78 5,031 December 31, 2020 Lease liabilities (short-term) 981 21 1,002 Lease liabilities (long-term) 2,421 44 2,465 Total lease liabilities 3,402 65 3,467 The Company does not recognize right-of-use assets for short-term and low value leases. The Company has no low value leases. Expense relating to short-term leases incurred during 2020 and 2019 is recorded in the Consolidated Statement of Operation in an amount of KUSD 277 and KUSD 28, respectively. The amount payable in 2021 under short-term leases (with an original term of under 12 months) is KUSD 130.

Intangible assets

Intangible assets	12 Months Ended
	Dec. 31, 2020
Intangible Assets [Abstract]
Intangible assets	Intangible assets (in KUSD) Licenses Software Total Cost January 1, 2019 7,490 87 7,577 Additions 1,731 59 1,790 Exchange difference — 1 1 December 31, 2019 9,221 147 9,368 Additions 1,923 85 2,008 Disposals — (65) (65) Exchange difference — 1 1 December 31, 2020 11,144 168 11,312 Accumulated amortization January 1, 2019 (853) (50) (903) Amortization charge — (30) (30) Exchange difference — (1) (1) December 31, 2019 (853) (81) (934) Amortization charge — (47) (47) Impairment charge (216) — (216) Disposals — 65 65 Exchange difference — (1) (1) December 31, 2020 (1,069) (64) (1,133) Net book amount December 31, 2019 8,368 66 8,434 December 31, 2020 10,075 104 10,179 Amortization and impairment of intangible assets have been charged to the following categories in the Consolidated Statement of Operation: (in KUSD) Year ended December 31, 2020 Year ended December 31, 2019 Year ended December 31, 2018 R&D expenses 230 14 244 G&A expenses 33 16 8 263 30 252 Licenses Licenses classified as definite-lived intangible assets are amortized over their useful lives, which are determined on the basis of the expected pattern of consumption of the expected future economic benefits embodied in the licenses and which therefore commence only once the necessary regulatory and marketing approval has been received for the product candidates to which they relate. To date, the Company has not received any regulatory and marketing approval for any of its product candidates and therefore classifies all of its licenses as indefinite-lived intangible assets. Consequently, the Company did not recognize any amortization expense of licenses. The Company has capitalized certain payments for licenses, in accordance with its accounting policy note 3.6, “Intangible assets”. The largest amount paid to any one party was KUSD 2,500 paid to Spirogen Ltd. in 2011 under a license and collaboration agreement, pursuant to which Spirogen Ltd. granted the Company access to its next-generation PBD-based warhead and linker technology. As a result of changes to the ownership of Spirogen Ltd. and of the applicable intellectual property rights, the agreement was subsequently amended and restated (with retroactive effect to September 2011) with MedImmune replacing Spirogen Ltd. as the licensor thereunder. Under the terms of the agreement, MedImmune has granted the Company an exclusive, worldwide license under certain patent rights and related know-how to make, have made, use, sell, offer for sale and import product candidates in the field of human therapeutics and diagnostics that consist of (i) PBD-based molecules directly conjugated to an antibody (i.e., ADCs with a PBD-based warhead) that specifically bind to up to 11 approved targets (“ADC Targets”), and (ii) PBD-based molecules conjugated to a non-antibody (i.e., targeting-moiety conjugates with a PBD-based warhead) that specifically bind to up to ten approved targets (“XDC Targets”). As of December 31, 2020, there are 11 approved ADC Targets subject to the license, including CD19 (the target of Lonca) and CD25 (the target of camidanlumab tesirine (“Cami” and previously known as ADCT-301), and ten approved non-ADC Targets subject to the license. Under the terms of the agreement, the Company has the right to grant sublicenses to affiliates and, subject to MedImmune’s approval (not to be unreasonably withheld), third parties. In addition, with respect to each licensed target, the Company has agreed to use commercially reasonable efforts to develop and commercialize at least one product and submit an IND application with the FDA (or its equivalent in another jurisdiction) for one product within 48 months after formal designation of the target as an approved replacement target, which the Company has done with respect to CD19 and CD25 upon submitting the IND applications for Lonca and Cami, respectively. The Company is required to make no further payments to Spirogen Ltd or Medimmune, beyond the upfront licensing fee of USD 2.5 million paid in 2011, in consideration for the rights granted under the agreement. In 2020, the Company capitalized the following license payments: – An amount of KUSD 1,000 relating to a license agreement with a third party to use their novel and proprietary conjugation technology with a variety of payload technologies in the development, manufacturing and commercialization of antibody drug conjugates. – An amount of KUSD 548 relating to a worldwide exclusive license with a third party to use their specific binding proteins in the development, manufacturing and commercialization of products. – An amount of KUSD 250 relating to a license agreement with a third party to acquire an antibody to be used in the development, manufacturing and commercialization of products. – An amount of KUSD 125 relating to license agreements with a third party to use their technology to generate antibody-drug conjugates for up to five antibodies. In 2019, the Company capitalized the following license payments: – An amount of KUSD 1,000 relating to a license agreement with a third party to acquire an antibody to be used in pre-clinical formalization, clinical testing, manufacturing and commercialization was capitalized as intangible assets. – An amount of KUSD 500 relating to a license agreement with a third party to use their technology to generate antibody-drug conjugates for up to five antibodies was capitalized as intangible assets. – An amount of KUSD 231 relating to a license agreement with a third party to use their technology for the production of antibodies was capitalized as intangible assets. Impairment testing The Group performed an assessment of its licenses in the context of its annual impairment test. Given the stage of the Group's development activities, the Group performed the impairment test on the basis of a fair value model for the entire group using the Company’s market capitalization. The group therefore performs their annual impairment tests on their entire portfolio of intangible assets, by deriving their fair value from the market capitalization for the entire group based on the Company’s closing share price of its common stock traded on the NYSE as of the Company’s annual impairment testing date. The fair value of the intangible asset portfolio was derived by deducting the carrying value of its tangible assets, which consist primarily of cash and cash equivalents, from the Group valuation. This resulted in a derived fair value of its portfolio of intangibles that was multiple times the carrying value of its intangibles. Management's estimate of the fair value is consistent with the approach taken in prior years with the exception of deriving the value of the entire group in 2020 based on the market capitalization of the Company’s common stock traded on the NYSE and with external sources of information during 2019 and 2018 (level 3 assessment). Each of the product candidates related to the capitalized intangible assets not yet available for use was additionally tested for impairment. Assessments included reviews of the following indicators: – Historical expenditure on clinical trials, future contractual commitments and internal budgets approved by the Board of Directors for ongoing and future trials; – Consideration of the progress of clinical trials, including obtaining primary endpoint readout data, discussions with regulatory authorities for new trials and enrollment status for ongoing clinical trials; – Consideration of market potential, supported where available by external market studies, and assessments of competitor products and product candidates. If a candidate fails any of those indicators, the entire balance is written off. During 2020 and 2018, the Company terminated a program in each year. Consequently, impairment charges of KUSD 216 and KUSD 227 (corresponding to the entire carrying amount of the capitalized licenses) were recognized and charged to R&D expenses in the Consolidated Statement of Operation. No impairment losses were recognized in 2019.

Financial instruments

Financial instruments	12 Months Ended
	Dec. 31, 2020
Financial Instruments [Abstract]
Financial instruments	Financial instruments by class and by category The accounting policies for financial instruments have been applied as indicated below: (in KUSD) Note December 31, 2020 December 31, 2019 Financial assets - financial assets Cash and cash equivalents 5.1 / 17b 439,195 115,551 Other current assets (excluding prepaid expenses) 12 3,100 2,840 Other long-term assets 397 368 Total financial assets (1) 442,692 118,759 (in KUSD) Note December 31, 2020 December 31, 2019 Financial liabilities - financial liabilities Trade accounts payable 5,279 3,329 Accrued liabilities and other payables 19 30,375 15,430 Lease liabilities, short-term and long-term 15 3,467 5,031 Convertible loans, short-term and long-term 21 38,406 — Convertible loans, derivatives 21 73,208 — Other long-term liabilities 221 — Total financial liabilities (1) 150,956 23,790 Net financial position 291,736 94,969 (1) Financial assets and Financial liabilities are recorded at historical or amortized cost with the exception of Convertible loans, derivatives which are recorded at fair value. The following is the net debt rollforward for the Company for 2020. No net debt rollforward was presented for 2019 as the Company’s only debt obligation related to its lease liabilities, which were deemed not to be material. Notes Cash and cash equivalents Convertible loan (1) Embedded derivative (1) Lease liabilities (2) Total December 31, 2019 115,551 — — (5,031) 110,520 Issuance of convertible loan 21 65,000 (37,203) (27,797) — — Convertible loan transaction costs 21 (3,673) 2,102 — — (1,571) Fair value adjustments 21 — — (23,432) — (23,432) Convertible loan accretion 21 — (4,756) — — (4,756) Interest payments (1,557) 1,452 105 — Lease principal 15 (1,144) — — 1,144 — Other lease activity including foreign exchange 15 — — — 315 315 Net cash outflow 264,783 — — — 264,783 Foreign exchange on cash 235 — — — 235 December 31, 2020 (3) 439,195 (38,406) (51,229) (3,467) 346,093 (1) See note 21, “Convertible loans for further information. (2) See note 15, “Leases” for further information. (3) Totals may not foot due to rounding. The credit quality of financial assets that are neither past due nor impaired is assessed below by reference to S&P’s credit ratings (where available) or to historical information about counterparty default rates: (in KUSD) December 31, 2020 December 31, 2019 Cash and cash equivalents UBS 144,989 51,983 Credit Suisse 145,238 62,652 JP Morgan Chase 3,768 916 Bank of America 145,200 — 439,195 115,551 Other current assets (excluding prepaid expenses) and other long-term assets are fully performing, not past due and not impaired (see note 12, “Other current assets” and note 17a, “Financial instruments by class and by category”).

Deferred income taxes and tax c

Deferred income taxes and tax credit	12 Months Ended
	Dec. 31, 2020
Income Taxes [Abstract]
Deferred income taxes and tax credit	Deferred income taxes and tax credit Unrecognized temporary differences, unused tax losses and unused tax credits (in KUSD) December 31, 2020 December 31, 2019 Deductible temporary differences, unused tax losses and unused tax credits for which no deferred tax assets have been recognized are attributable to the following: Taxes losses 613,206 437,013 Unused R&D US tax credit 26,255 10,765 Deductible temporary differences related to the retirement benefit plan 3,543 2,684 Deductible temporary differences related to IFRS 16 338 (39) Offset of recognized temporary differences related to intangible assets (2,364) (2,364) Temporary difference related to investment in joint venture (24,368) — Temporary difference related to convertible loan (27,614) — Total 588,996 448,059 Tax loss carryforwards Potential deferred income tax assets from tax loss carryforwards exceed deferred tax liabilities. Deferred income tax assets from tax loss carryforwards are initially recognized to the extent of suitable deferred income tax liabilities, then to the extent that the realization of the related tax benefit through future taxable profits is probable. On this basis, the Company has decided not to recognize any deferred income tax assets at December 31, 2020 or 2019. The amounts of deferred income tax assets that arise from sources other than tax loss carryforwards and the amounts of deferred income tax liabilities are insignificant in comparison to the unrecognized tax loss carryforwards. Tax losses not recognized and to be carried forward (in KUSD): Years of expiry December 31, 2020 December 31, 2019 2020 — 14,735 2021 19,889 19,889 2022 31,128 31,128 2023 38,441 38,441 2024 92,012 92,012 Beyond 2025 431,736 240,808 613,206 437,013 All of these carryforwards relate to the Company. In 2020, unused tax losses of KUSD 14,735 expired (2019: KUSD 6,209). Deferred income tax assets from USA R&D tax credit carryforwards are recognized to the extent that the realization of the related tax benefit through future taxable profits is probable. On this basis, the Group has not recognized deferred tax assets related to the following tax credits carried forward: R&D USA tax credits carried forward (in KUSD): Years of expiry December 31, 2020 December 31, 2019 2036 1,059 783 2037 2,569 1,839 2038 7,117 3,387 2039 7,026 4,756 2040 8,484 — 26,255 10,765 An amount of KUSD 546 was utilized in 2020 (KUSD 436 in 2019), as per note 11 “Income tax expenses”. These R&D tax credits, which may be carried forward for up to 20 years, relate entirely to ADCT America.

Accrued liabilities and other p

Accrued liabilities and other payables	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Accrued liabilities and other payables	Accrued liabilities and other payables (in KUSD) December 31, 2020 December 31, 2019 Payroll and social charges 12,063 5,726 R&D costs 15,333 8,922 Other 2,979 782 30,375 15,430

Pension obligations

Pension obligations	12 Months Ended
	Dec. 31, 2020
Employee Benefits [Abstract]
Pension obligations	Pension obligations The Swiss pension plan is classified as a defined benefit plan under IFRS. Certain employees of the UK subsidiary are covered by local defined contribution plans. Pension costs for these plans are charged to the Consolidated Statement of Operation when incurred. Swiss pension plan The Company contracted with the Swiss Life Collective BVG Foundation based in Zurich for the provision of occupational benefits. All benefits in accordance with the regulations are reinsured in their entirety with Swiss Life SA within the framework of the corresponding contract. This pension solution fully reinsures the risks of disability, death and longevity with Swiss Life. Swiss Life invests the vested pension capital and provides a 100% capital and interest guarantee. The pension plan is entitled to an annual bonus from Swiss Life comprising the effective savings, risk and cost results. Although, as is the case with many Swiss pension plans, the amount of ultimate pension benefit is not defined, certain legal obligations of the plan create constructive obligations on the employer to pay further contributions to fund an eventual deficit; this results in the plan nevertheless being accounted for as a defined benefit plan. In 2020, the guaranteed interest to be credited to employees' savings was 1% for mandatory retirement savings and 0.125% for supplementary retirement savings. While the rate for converting mandatory savings to an annuity remains fixed by statute at 6.8%, the rate for converting supplementary savings to an annuity at age 65 for male and 64 for female employees was reduced for the period 2020-2022 from 5.0980% to 4.7120% for male and from 5.0995% to 4.7626% for female employees. The Swiss defined benefit plan scheme is valued by independent actuaries every year using the projected unit credit method. The latest actuarial valuation was carried out as at December 31, 2020. The net amount recognized on the balance sheet comprises: (in KUSD) December 31, 2020 December 31, 2019 Present value of defined benefit obligation for funded plan 11,809 7,880 Fair value of plan assets (8,266) (5,196) Deficit of funded plan: liability on the balance sheet 3,543 2,684 The movement in the net defined benefit obligation over the year is as follows: (in KUSD) Present value Fair value of Total Defined benefit plan - pension costs: January 1, 2019 4,372 (2,986) 1,386 Current service cost 769 — 769 Impact of plan changes (319) — (319) Interest cost / (income) 37 (25) 12 Defined benefit plan - pension costs 487 (25) 462 Employee contributions 257 (257) — Employer contributions — (515) (515) Transfers from joiners' previous plans 1,302 (1,302) — 1,559 (2,074) (515) Exchange differences 74 (69) 5 Remeasurements: Change in financial assumptions 686 — 686 Other actuarial losses 609 — 609 Plan asset gains — (2) (2) Exchange differences 93 (40) 53 Remeasurements 1,388 (42) 1,346 December 31, 2019 7,880 (5,196) 2,684 (in KUSD) Present value Fair value of Total Defined benefit plan - pension costs: January 1, 2020 7,880 (5,196) 2,684 Current service cost 960 — 960 Interest cost / (income) 17 (11) 6 Defined benefit plan - pension costs 977 (11) 966 Employee contributions 348 (348) — Employer contributions — (690) (690) Transfers from joiners' previous plans 1,451 (1,451) — 1,799 (2,489) (690) Exchange differences 838 (560) 278 Remeasurements: Other actuarial losses 775 — 775 Plan asset gains — (10) (10) Change in demographic assumptions (460) — (460) Remeasurements 315 315 (10) 305 December 31, 2020 11,809 (8,266) 3,543 The changes in demographic assumptions utilized in the valuation had a positive impact in the present value of pension obligations in 2020. More specifically, the benefit arose from using an updated mortality table as described below. The other actuarial losses in 2020 were due to a variety of experience factors, including in particular the increase in 2020, after the service cost for 2020 had been determined, in the number of active employees covered by the pension plan. The present value of the defined benefit obligation related to 28 active employees based in Switzerland (2019: 22 active employees). The principal actuarial assumptions used for accounting purposes are as follows for all periods presented: 2020 2019 Discount rate 0.20 % 0.20 % Interest credited on savings accounts 0.20 % 0.20 % Future salary increases 1.50 % 1.50 % Future pension increases 0.00 % 0.00 % Assumptions regarding future mortality experience are set based on actuarial advice provided in accordance with published statistics and experience in each territory. Mortality assumptions for Switzerland are based on the LPP 2020 and LPP 2015 mortality generational tables for 2020 and 2019, respectively. The average life expectancy in years after retirement of a pensioner retiring at age 65 (male) and 64 (female) on the balance sheet date is as follows: 2020 2019 Male 22.45 22.61 Female 25.26 25.64 The sensitivity of the defined benefit obligation and of the service cost to changes in the weighted principal assumption is: 2020 Increase in Impact on defined Decrease in Impact on defined Discount rate 0.25 % (5.00) % (0.25) % 5.40 % Future salary increases 0.50 % 0.70 % (0.50) % (0.70) % Interest credited on savings accounts 0.50 % 2.80 % (0.50) % (2.70) % Future pension increases 0.50 % 6.70 % (0.50) % (6.00) % 2019 Increase in Impact on defined Decrease in Impact on defined Discount rate 0.25 % (5.40) % (0.25) % 5.90 % Future salary increases 0.50 % 0.90 % (0.50) % (0.90) % Interest credited on savings accounts 0.50 % 3.20 % (0.50) % (3.00) % Future pension increases 0.50 % 7.00 % (0.50) % (6.30) % The above sensitivity analyses are based on a change in an assumption while holding all other assumptions constant. In practice, this is unlikely to occur, and changes in some of the assumptions may be correlated. When calculating the sensitivity of the defined benefit obligation to significant actuarial assumptions the same method (present value of the defined benefit obligation calculated with the projected unit credit method at the end of the reporting period) has been applied as when calculating the pension liability recognized within the statement of financial position. The methods and types of assumptions used in preparing the sensitivity analysis did not change compared to the prior period. Expected employer contributions to the defined benefit plan for the year ending December 31, 2021 amount to KUSD 774. The weighted average duration of the defined benefit obligation is 20.9 years (2019: 22.7 years). Asset-liability strategy The Swiss Life Collective BVG Foundation, to which the pension plan is affiliated, manages its funds in the interests of all members, with due attention to the priorities of liquidity, security and return. The Company’s pension plan benefits from the economies of scale and diversification of risk available through this affiliation. Investments by asset class Investments by asset class are as follows: (in KUSD) December 31, 2020 December 31, 2019 Cash 126 155 Bonds 4,658 3,065 Shares 564 329 Real estates and mortgages 2,353 1,303 Alternative investments 565 344 8,266 5,196 Defined benefit plan reserves The movement in the defined benefit plan reserves (included in “Other reserves”) is as follows: (in KUSD) 2020 2019 January 1 (2,389) (1,043) Remeasurements of defined benefit pension plan (305) (1,346) December 31 (2,694) (2,389)

Convertible loans

Convertible loans	12 Months Ended
	Dec. 31, 2020
Financial Instruments [Abstract]
Convertible loans	Convertible loans Facility agreement On April 24, 2020, the Company entered into a USD 115.0 million Facility Agreement with Deerfield Partners, L.P. and certain of its affiliates (“Deerfield”). Pursuant to such agreement, Deerfield agreed to extend senior secured convertible term loans to the Company in two separate disbursements: (i) an initial disbursement of convertible loans in the amount of USD 65.0 million upon the completion of the IPO, and satisfaction of certain other conditions (the “first tranche”) and (ii) a subsequent disbursement of convertible loans in the amount of USD 50.0 million upon the receipt of regulatory approval for Lonca, and satisfaction of certain other conditions (the “second tranche”). The outstanding principal amount of the convertible loans is due to be repaid in full on the fifth anniversary of the date on which the first tranche was funded, which occurred on May 19, 2020. However, any conversion of the convertible loans into common shares shall be deemed a repayment of the principal amount of the convertible loans so converted. The convertible loans bear interest at a rate of 5.95% per annum, based on a 360-day year, with interest payable quarterly in arrears commencing July 1, 2020. Upon any payment of the convertible loans or conversion of the convertible notes, whether upon redemption or at maturity or at any other time, the Company will be required to pay an exit charge equal to 2.0% of the amount of the loans so paid or converted. The Company’s obligations under the Facility Agreement are guaranteed by the Company’s wholly-owned subsidiaries and secured by a perfected, first-priority security interest in substantially all of the Company’s and its wholly-owned subsidiaries’ personal property, including its intellectual property and the equity ownership interests directly and indirectly held by the Company in its wholly-owned subsidiaries and in Overland ADCT BioPharma. Each convertible loan extended under the Facility Agreement is evidenced by a convertible note. The holder of each of the first tranche of convertible notes is entitled to convert the principal amount of convertible loans evidenced thereby, at its option, into the Company’s common shares at any time at a conversion price per share equal to 130% of the IPO share price, which was USD 19.00. The conversion price for the second tranche of convertible notes is the lesser of (i) 150% of the IPO price and (ii) 120% of the average of the volume-weighted average prices of the Company’s common shares on each of the 15 trading days immediately prior to the disbursement date of the second tranche, but in no event less than a floor equal to 81% of the IPO price. If the conversion price of the second tranche of convertible notes is less than the floor price but for the application of the floor, Deerfield will not be obligated to extend the second tranche. Upon the occurrence of a major transaction, as defined below, the holders of the convertible notes may elect to require the Company to redeem all or any portion of the notes for an amount equal to the principal amount thereof (in addition to accrued and unpaid interest, the make-whole amount and the exit charge) or alternatively the holder may elect to require the Company to convert the unredeemed portion and, in addition, receive a number of additional common shares determined as set forth in the convertible notes (in addition to accrued and unpaid interest and the exit charge). In the case of a successor major transaction, as defined below, the Company may elect to require redemption of any portion of the convertible notes that the holder does not elect to convert in connection with such transaction. Major transactions include (i) mergers and similar transactions as a result of which the holders of common shares before the transaction no longer hold a majority of the common shares after the transaction or the common shares are changed into the securities of another entity, (ii) sales of assets exceeding 50% of the Company’s enterprise value, (iii) any person or group acquiring beneficial ownership of more than 50% of the Company’s common shares or (iv) the delisting of the Company’s common shares, subject in each case to the more detailed provisions contained in the convertible notes. Successor major transactions include any major transaction in which the Company’s common shares are converted into the right to receive cash, securities of another entity and/or other assets, and any asset sale major transaction in which the Company distributes assets to its shareholders. The Company will have the right to force conversions of the convertible notes on and after the one-year anniversary of the date on which it has received regulatory approval of Lonca if each of the following is greater than 275% of the conversion price (among other conditions specified in the convertible notes): (1) the volume weighted average price of the common shares on at least 20 trading days during any period of 30 consecutive trading days, (2) the volume weighted average price of the common shares on the last trading day of such period and (3) the closing price of the common shares on the last trading day of such period. The Company will have the right to force conversions of the convertible notes on and after the three-year anniversary of the date on which it has received regulatory approval of Lonca if the same conditions above are satisfied, except that the applicable price described in the preceding sentence need only be greater than 175% of the conversion price. The Company is obligated to draw down the second tranche upon receipt of regulatory approval for Lonca. If the Company has not received the regulatory approval on or prior to December 31, 2021, the second tranche will automatically terminate on such date. The Facility Agreement contains various covenants, including a requirement to retain USD 50.0 million in cash and cash equivalents as of the end of each fiscal quarter. Bifurcation of first tranche The first tranche of convertible loans amounting to USD 65.0 million issued on May 19, 2020 has been accounted for as comprising two components: an embedded conversion option derivative and a loan, as explained in note 3, “Significant accounting policies”. Valuation of derivative embedded in first tranche The Company has used an independent valuation firm to assist in calculating the fair value of the embedded conversion option derivative, which is based on the mean of values derived from application of the Hull and Goldman Sachs convertible bond pricing models. Key inputs for the valuations as of December 31, 2020 and April 24, 2020 were as follows: As of December 31, 2020 April 24, 2020 Exercise price, in USD 24.70 22.10 Forced conversion price, in USD 67.93 60.78 Share price in USD 32.01 17.00 Risk-free interest rate 0.3 % 0.4 % Expected volatility 90 % 82 % Expected term 52 months 61 months Dividend yield — — Recovery rate 5 % 5 % Implied bond yield 13.3 % 21.0 % On the basis of the valuation of the conversion option derivative as of April 24, 2020, the USD 65.0 million amount of the first tranche of convertible loans was accounted for on inception as follows: in KUSD Embedded derivative Residual Total Gross proceeds 27,797 37,203 65,000 Less: transaction costs (1,571) (2,102) (3,673) Net 26,226 35,101 61,327 The transaction costs of the embedded derivative were charged directly to the Consolidated Statement of Operation. The fair value of the embedded derivative associated with the first tranche was KUSD 51,229 and KUSD 27,797 as of December 31, 2020 and April 24, 2020, respectively. The increase in fair value of the embedded derivative during the year ended December 31, 2020 is primarily due to the increase in the fair value of the underlying shares from April 24, 2020 to December 31, 2020. During the year ended December 31, 2020, the Company recognized a loss of KUSD 23,432 as a result of changes in the fair value of the embedded derivative, which was charged directly to the Consolidated Statement of Operation. Accounting for residual loan of first tranche As illustrated in the table above and in accordance with IFRS 9, the transaction costs of the residual convertible loan (net of the value of the embedded derivative) were deducted from the loan to arrive at the deemed net present value as of May 19, 2020 of all future cash outflows associated with the loan. The implied effective interest rate that would be needed to increase the book value of the loan to cover all future outflows, taking into account the deduction of transaction costs from the initial loan balance and based on a 365-day year, was computed at inception at 23% and will be applied over the life of the loan. For year ended December 31, 2020, the Company recorded interest expense related to the interest payable on the residual convertible loan (net of the value of the embedded conversion option derivative) in the amount of KUSD 4,756 based on the implied effective interest rate. The amount at which the convertible loan is presented as a liability in the Consolidated Balance Sheet represents the net present value of all future cash outflows associated with the loan discounted at the implied effective interest rate. The net present value of those cash outflows occurring within 12 months of the balance sheet date discounted at the same rate is presented as a short-term liability. The remainder of the amount is presented as a long-term liability. The carrying value of the convertible loan was KUSD 38,406 as of December 31, 2020, of which KUSD 34,775 was the non-current portion of the liability and KUSD 3,631 was the current portion of the liability. Accounting for second tranche The obligation to draw down the second tranche under the terms specified in the Facility Agreement has been accounted for as a derivative. The Company has used an independent valuation firm to assist in calculating the fair value of the derivative, which is based on the mean of values derived from application of the Hull and Goldman Sachs convertible bond pricing models. Key inputs for the valuation as of December 31, 2020 were as follows: As of December 31, 2020 Exercise price, in USD 28.50 Forced conversion price, in USD 78.38 Share price in USD 32.01 Risk-free interest rate 0.3 % Expected volatility 90 % Expected term 5 months Dividend yield — Recovery rate 5 % Implied bond yield 7.4 % In addition to the key inputs disclosed above for the second tranche, the Company estimated the probability of achieving regulatory approval for Lonca. For purposes of its December 31, 2020 valuation, the Company estimated it was highly probable that it would receive regulatory approval for Lonca. Significant changes which increase or decrease the probabilities of achieving the related regulatory events, or shorten or lengthen the time required to achieve such events would result in a corresponding increase or decrease in the fair value of this derivative liability. During the year ended December 31, 2020, the Company recognized a loss of KUSD 21,979 as a result of changes in the fair value of the derivative. The fair value of the derivative associated with the second tranche was KUSD 21,979 as of December 31, 2020, which was presented as a financial liability in the Consolidated Balance Sheet. The increase in fair value of the derivative during year ended December 31, 2020 is primarily due to the increase in the fair value of the underlying shares, which was charged directly to the Consolidated Statement of Operation. The value of the derivative is directly correlated with the probability estimate of obtaining regulatory approval for Lonca. An increase or decrease of 10% in the estimated probability would have resulted in an increase or decrease in the value of the derivative of KUSD 2,198.

Share-based compensation expens

Share-based compensation expense	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangements [Abstract]
Share-based compensation expense	Share-based compensation expense Share data have been revised to give effect to the share split and share consolidation explained in note 2 (iv) “Share split” and in note 2 (v) “Share consolidation”. Share Purchase Plan 2013 and Share Purchase Plan 2016 Under the terms of the 2013 and 2016 promissory notes issued in connection with the Share Purchase Plan 2013 and Share Purchase Plan 2016, in the case of an IPO the relevant plan participants were required to repay the outstanding amounts under the promissory notes prior to the IPO by delivering a number of shares of equivalent value to cover the amount to be repaid. In anticipation of the IPO, each of the plan participants holding promissory notes entered into loan settlement agreements with the Company dated as of April 15, 2020 pursuant to which they repaid all amounts outstanding under the promissory notes, including accrued interest, by delivering a number of shares of equivalent value to cover the amounts outstanding under the promissory notes. After consideration of all relevant factors, the Board of Directors determined the value of such shares delivered pursuant to the loan settlement agreements as of the settlement date to be USD 18.75 per share, resulting in the delivery of an aggregate of 597,774 common shares by all plan participants for the settlement of the promissory notes. These shares were held by the Company as treasury shares. These transactions resulted in the termination of both plans on May 15, 2020. All compensation expense relating to the ADC Therapeutics SA 2013 Share Purchase Plan (the “Share Purchase Plan 2013”) was recognized in prior periods. During the year ended December 31, 2020, unrecognized expense relating to the Share Purchase Plan 2016 amounting to KUSD 6,425 was charged to the Consolidated Statement of Operation with a corresponding increase to Other reserves within equity on the Consolidated Balance Sheet on completion of these transactions. The amounts of expense for all awards recognized for services received during the year ended December 31, 2020 was KUSD 7,417 (including the KUSD 6,425 discussed above). The amount of expense recognized for the years ended December 31, 2019 and December 2018 was KUSD 332 and KUSD 361, respectively. There was no expense recognized for the Share Purchase Plan 2013 for the years ended December 31, 2020, 2019 and 2018. Incentive Plan 2014 All existing awards under the Incentive Plan 2014 vested and were settled in shares upon the completion of the IPO. The Company calculated for each participant the gain arising from the difference between the exercise price and the USD 19.00 IPO price, undertook to settle in cash on behalf of the participant any associated tax and social charges liability, and transferred to the participant the remaining balance from treasury shares, valued at USD 19.00 per share. A total of 356,144 common shares were transferred to participants and an amount of KUSD 5,343 was withheld for tax and social charges during fiscal year 2020. For participants whose awards had an exercise price greater than USD 19.00 — i.e., were “out-of-the-money” — the Company made an equal number of new awards under the Equity Incentive Plan 2019 (see below) with an exercise price of USD 19.00 and with a vesting period of only three years instead of the usual four years. These new awards have been accounted for as a modification of the previous awards under the Incentive Plan 2014. Accordingly, the original compensation expense calculated for the old awards that were “out-of-the-money” will continue to be recognized over their remaining vesting period while the expense to be recognized for the new awards under the 2019 Equity Incentive Plan will be limited to the incremental fair value of the new awards over the fair value, as of May 15, 2020, of the old awards. The amounts of expense for all awards recognized for services received during the periods ended December 31, 2020, 2019 and 2018 were KUSD 361, KUSD 437 and KUSD 108, respectively. 2019 Equity Incentive Plan In November 2019, the Company adopted the 2019 Equity Incentive Plan. Under the 2019 Equity Incentive Plan, the Company may at its discretion grant to plan participants, such as directors, certain employees and service providers, awards in the form of restricted shares and restricted share units (“RSUs”), share options, share appreciation rights, performance awards and other share-based awards. The Company has reserved 7,820,000 common shares for future issuance under the 2019 Equity Incentive Plan, which include common shares pursuant to share-based equity awards issued to date. As of December 31, 2020, the Company has 3,390,148 common shares available for the future issuance of share-based equity awards. As of December 31, 2020, the cumulative amount recorded as an increase to Other Reserves within equity on the Consolidated Balance Sheet in respect of the 2019 Equity Incentive Plan was KUSD 35,498. The amounts of expense for all awards recognized for services received during the years ended December 31, 2020 and 2019 were KUSD 35,150 and KUSD 348, respectively. Share Options Pursuant to the 2019 Equity Incentive Plan, the Company may grant share options to its directors, certain employees and service providers working for the benefit of the Company at the time. The exercise price per share option is set by the Company at the fair market value of the underlying common shares on the date of grant, as determined by the Company, which is generally the closing share price of the Company’s common shares traded on the NYSE. The awards generally vest 25% on the first anniversary of the date of grant, and thereafter evenly on a monthly basis over the subsequent three years. The contractual term of each share option award granted is ten years. Under the grant, the options may be settled only in common shares of the Company. Therefore, the grants of share options under the 2019 Equity Incentive Plan have been accounted for as equity-settled under IFRS 2. As such, the Company records a charge for the vested portion of award grants and for partially earned but non-vested portions of award grants. This results in a front-loaded charge to the Company’s Consolidated Statement of Operation and a corresponding increase to Other Reserves within equity on the Consolidated Balance Sheet. The expense recognized for services received during the years ended December 31, 2020, and 2019 is KUSD 33,355 and KUSD 348, respectively. There was no expense recognized under the 2019 Equity Incentive Plan for the year ended December 31, 2018. Movements in the number of awards outstanding and their related weighted average strike prices are as follows: 2020 2019 Average strike price in USD per share Number of awards Average strike price in USD per share Number of awards At the beginning of the year 18.75 1,020,434 — — Granted 28.62 3,347,766 18.75 1,020,434 Forfeited 19.83 (88,332) — — Exercised 18.75 (2,895) — — At the end of the year 26.45 4,276,973 18.75 1,020,434 Weighted average remaining contractual life of awards outstanding at end of period 9.29 9.96 The option awards granted during the year ended December 31, 2020 include 388,333 awards that were made to compensate holders of “out-of-the-money” awards under the Incentive Plan 2014 that expired on May 15, 2020. As of December 31, 2020, 244,291 awards are vested and exercisable out of the total outstanding awards of 4,276,973 common shares. No awards have expired. As of December 31, 2020, the weighted average strike price and weighted average remaining life for vested and exercisable awards is USD 18.75 and 8.94 years, respectively. Awards outstanding at the end of the year have the following expiry date and strike prices: Grant date Expiry date Strike price Awards December 31, 2020 December 9, 2019 2029 18.75 985,848 April 1, 2020 2030 18.75 213,764 April 29, 2020 2030 18.75 1,272,213 May 15, 2020 2030 19.00 366,257 June 4, 2020 2030 34.99 341,403 July 1, 2020 2030 48.77 84,589 July 20, 2020 2030 48.59 490,883 August 3, 2020 2030 46.83 61,576 August 17, 2020 2030 38.62 135,064 September 1, 2020 2030 41.19 125,850 October 1, 2020 2030 32.15 101,875 November 2, 2020 2030 29.01 40,220 December 1, 2020 2030 38.02 57,431 Total 4,276,973 The average grant date fair value of awards granted during the year ended December 31, 2020 was USD 21.27 per award (2019: USD 15.71). The fair values of the options granted after the IPO were determined on the date of the grant using the Black-Scholes option-pricing model. Prior to the IPO, the fair value of the options granted were determined using an adjusted form of the Black-Scholes option pricing model. The Company has used an independent valuation firm to assist in calculating the fair value of the award grants per participant. See note 6, “Critical accounting estimates and judgements”. The fair values of the options granted during the years ended December 31, 2020 and 2019 were determined on the date of grant using the following assumptions: Year ended December 31, 2020 Year ended December 31, 2019 a) weighted average share price in USD 15.95-48.77 16.31 b) strike price in USD 18.75-48.77 18.75 c) expected volatility in % 80-206 176.6 d) award life in # of years 5.02-6.08 5.65 e) expected dividends in % 0 0 f) risk-free interest rate in % 0.29-0.70 1.67 The expected volatility for options granted was based on historical volatility and selected volatility determined by median values observed among comparable public companies. The award life for options granted was based on the time interval between the date of grant and the date during the ten-year life after which, when making the grant, the Company expected on average that participants would exercise their options. RSUs Pursuant to the 2019 Equity Incentive Plan, the Company may grant RSUs to its directors, certain employees and service providers working for the benefit of the Company at the time. The awards generally vest annually over a period of three years commencing on the first anniversary of the date of grant. Under the grant, the RSUs may be settled only in common shares of the Company. Therefore, the grant of RSUs under the 2019 Equity Incentive Plan have been accounted for as equity-settled under IFRS 2. As such, the Company records a charge for the vested portion of award grants and for partially earned but non-vested portions of award grants. This results in a front-loaded charge to the Company’s Consolidated Statement of Operation and a corresponding increase to Other Reserves within equity on the Consolidated Balance Sheet. The expense recognized for services received during the year ended December 31, 2020 is KUSD 1,795. Number of awards Weighted average grant date fair value December 31, 2019 — — Granted 149,984 46.50 December 31, 2020 149,984 46.50 There were no vested RSUs as of December 31, 2020. Share-based Compensation Reserves The movement in the Share-based Compensation Reserves (included in Other reserves within equity) is as follows: (in KUSD) 2020 2019 2018 January 1 7,862 6,745 6,276 Incentive Plan 2014 361 437 108 Share Purchase Plan 2016 7,417 332 361 2019 Equity Incentive Plan - Options 33,355 348 — 2019 Equity Incentive Plan - RSUs 1,795 — — Tax and social charge deductions - Incentive Plan 2014 (5,343) — — December 31 45,447 7,862 6,745

Share capital

Share capital	12 Months Ended
	Dec. 31, 2020
Share Capital, Reserves And Other Equity Interest [Abstract]
Share capital	Share capital Share data have been revised to give effect to the share split and share consolidation as explained in note 2 (iv) and 2 (v), respectively. The movements in the Company’s share capital, share premium and treasury shares accounts for the years ended December 31, 2020, 2019 and 2018 are set out in the following table: Issued share capital Share premium Treasury shares Increase / (Decrease) in net assets Price per share Issued share capital Treasury shares Outstanding share capital In KUSD Number of shares issued Number of shares (held or received) / delivered Number of shares outstanding December 18, 2018 Issuance of share capital 4 — — 4 CHF 0.08 450,000 — 450,000 December 18, 2018 Transaction costs, issuance of share capital (28) — (28) — — — Movements during the year ended December 31, 2018 4 (28) — (24) 450,000 — 450,000 Balances as of January 1, 2018, revised for share consolidation and share split 397 452,296 — 452,693 47,375,000 — 47,375,000 Balance at December 31, 2018 401 452,268 — 452,669 47,825,000 — 47,825,000 February 6, 2019 Increase share capital 1 — — 1 CHF 0.008 75,000 — 75,000 February 6, 2019 Transaction costs, increase in share capital — (19) — (19) — — — June 7, 2019 Increase in share capital 22 75,578 — 75,600 CHF 0.008 2,700,000 — 2,700,000 June 7, 2019 Transaction costs, increase in share capital — (1,432) — (1,432) — — — June 14, 2019 Increase in share capital — 700 — 700 CHF 0.008 25,000 — 25,000 June 14, 2019 Transaction costs, increase in share capital — (13) — (13) — — — July 5, 2019 Increase in share capital 7 26,943 — 26,950 CHF 0.008 962,500 — 962,500 July 5, 2019 Transaction costs, increase in share capital — (306) — (306) — — — August 22, 2019 Transfer from share premium for par value increase 3,789 (3,789) — — — — — September 2, 2019 Purchase of treasury shares 141 — (141) — CHF 0.08 1,750,000 (1,750,000) — September 2, 2019 Transaction costs, increase in share capital — (8) — (8) — — — December 16, 2019 Sale of treasury shares — — 41 41 CHF 0.08 — 509,460 509,460 Movements during the year ended December 31, 2019 3,960 97,654 (100) 101,514 5,512,500 (1,240,540) 4,271,960 Balances as of January 1, 2019, revised for share consolidation and share split 401 452,268 — 452,669 47,825,000 — 47,825,000 Balance at December 31, 2019 4,361 549,922 (100) 554,183 53,337,500 (1,240,540) 52,096,960 April 15, 2020 Shares surrendered by Share Purchase Plan 2013 and Share Purchase Plan 2016 participants to settle share purchase plan promissory notes — 11,208 (11,208) — USD 18.75 — (597,774) (597,774) April 16, 2020 Issuance of shares per shareholder's agreement addendum through capitalization of reserves 393 (393) — — CHF 0.08 4,777,996 — 4,777,996 April 24, 2020 Elimination of fractional holdings — — — — CHF 0.08 — 51 51 May 19, 2020 Issuance of shares to be held as treasury 34 — (34) — CHF 0.08 408,873 (408,873) — May 19, 2020 Grant of shares to settle Incentive Plan 2014 awards, net — (29) 29 — CHF 0.08 — 356,144 356,144 May 19, 2020 Issuance of shares at IPO 1,007 231,661 — 232,668 USD 19.00 12,245,631 — 12,245,631 May 19, 2020 Sale of shares under greenshoe option — 23,591 11,309 34,900 USD 19.00 — 1,836,844 1,836,844 May 19, 2020 Transaction costs, IPO and greenshoe option — (23,355) — (23,355) — — — September 28, 2020 Issuance of shares at follow-on offering 519 203,481 — 204,000 USD 34.00 6,000,000 — 6,000,000 September 28, 2020 Transaction costs, follow-on offering — (15,084) — (15,084) — — — September 30, 2020 Other — — — — CHF 0.08 — 2,796 2,796 December 14, 2020 Shares issued for exercise of option awards — 34 — 34 CHF 0.08 — 1,861 1,861 December 16, 2020 Shares issued for exercise of option awards — 10 — 10 CHF 0.08 — 517 517 December 29, 2020 Shares issued for exercise of option awards — 10 — 10 CHF 0.08 — 517 517 Movements during the year ended December 31,2020 1,953 431,134 96 433,183 23,432,500 1,192,083 24,624,583 Balances reported at December 31, 2019, revised for share consolidation and share split 4,361 549,922 (100) 53,337,500 (1,240,540) 52,096,960 Balance at December 31, 2020 6,314 981,056 (4) 76,770,000 (48,457) 76,721,543 Authorized Capital The Board of Directors was authorized, subject to compliance with the Company's shareholder agreement, to increase the share capital at any time until April 23, 2022, by a maximum amount of CHF 2,080,000, by issuing a maximum of 26,000,000 common shares, fully paid up, with a par value of CHF 0.08 each. An increase of the share capital in partial amounts is permissible. As of December 31, 2020, the remaining maximum amount is CHF 2,080,000, which may be raised by issuing a maximum of 26,000,000 common shares. Conditional Share Capital Conditional Share Capital for Warrants and Convertible Bonds Our nominal share capital may be increased, including to prevent takeovers and changes in control, by a maximum aggregate amount of CHF 1,624,000 through the issuance of not more than 20,300,000 common shares, which would have to be fully paid-in, each with a par value of CHF 0.08 per share, by the exercise of option and conversion rights granted in connection with warrants, convertible bonds or similar instruments of the Company or one of its subsidiaries. Shareholders will not have pre-emptive subscription rights in such circumstances, but will have advance subscription rights to subscribe for such warrants, convertible bonds or similar instruments. The holders of warrants, convertible bonds or similar instruments are entitled to the new shares upon the occurrence of the applicable conversion feature. Conditional Share Capital for Equity Incentive Plans Our nominal share capital may, to the exclusion of the pre-emptive subscription rights and advance subscription rights of shareholders, be increased by a maximum aggregate amount of CHF 936,000 through the (direct or indirect) issuance of not more than 11,700,000 common shares, which would have to be fully paid-in, each with a par value of CHF 0.08 per share, by the exercise of options, other rights to receive shares or conversion rights that have been granted to employees, members of the board of directors, contractors or consultants of the Company or of one of its subsidiaries or other persons providing services to the Company or to a subsidiary through one or more equity incentive plans created by the board of directors. Dividend

Commitments

Commitments	12 Months Ended
	Dec. 31, 2020
Other Provisions, Contingent Liabilities And Contingent Assets [Abstract]
Commitments	Commitments The Company has contractual obligations as follows: Collaborations and co-operations with development partners The Company has entered into various collaborations with development partners, including in-licensing and manufacturing agreements. These agreements provide for the Company to make potential future milestone and royalty payments that are conditional on success, and that are spread over various stages of development and commercialization, including achieving preclinical proof of concept, filing an investigational new drug (“IND”) application, commencing or completing multiple clinical development stages, obtaining regulatory approval in multiple countries, and achieving various levels of commercial sales. Due to the nature of these arrangements, the future potential payments related to the attainment of the specified milestones are inherently uncertain, and accordingly, no amounts have been recorded for these future potential payments in the Company’s Consolidated Balance Sheets as of December 31, 2020 and 2019. As of December 31, 2020, the aggregate amount of such potential milestone payments, under all such collaboration agreements, was KUSD 350,422 (2019: KUSD 323,973). These milestone payments relate to product candidates in the following phases: (in KUSD): R&D Phase Development Regulatory Sales-based Total Pre-clinical 53,497 11,650 158,259 223,406 Phase I 23,719 19,000 73,500 116,219 Phase II 10,797 — — 10,797 December 31, 2020 88,013 30,650 231,759 350,422 R&D Phase Development Regulatory Sales-based Total Pre-clinical 55,290 19,000 118,000 192,290 Phase I 23,615 19,000 73,500 116,115 Phase II 15,568 — — 15,568 December 31, 2019 94,473 38,000 191,500 323,973 The net increase in the aggregate milestone payments from December 31, 2019 primarily relates to the license agreements entered in fiscal year 2020. See note 16, “Intangible assets” for further details.

Contingent liabilities

Contingent liabilities	12 Months Ended
	Dec. 31, 2020
Other Provisions, Contingent Liabilities And Contingent Assets [Abstract]
Contingent liabilities	Contingent liabilitiesThe Group has no contingent liabilities in respect of legal claims arising in the ordinary course of business. There are no material legal proceedings to which the Company is a party.

Related parties

Related parties	12 Months Ended
	Dec. 31, 2020
Related Party [Abstract]
Related parties	Related partiesParties are considered to be related if one party has the ability, directly or indirectly, to control the other party or exercise significant influence over the other party in making financial and operating decisions. A.T. Holdings II Sàrl (“AT Holdings II”) is a shareholder in the Company. AT Holdings II is in turn ultimately entirely owned by Auven Therapeutics Holdings, L.P. (“ATH”), a limited partnership registered in the British Virgin Islands. ATH’s General Partner is Auven Therapeutics General L.P., which itself is a limited partnership whose General Partner is Auven Therapeutics GP Ltd. The manager of ATH is Auven Therapeutics Management L.L.L.P. (“ATM”). Services provided by the Company The Company provides registered office and simple administrative services to four subsidiaries of ATH. The amounts invoiced in 2020, and recovered through G&A expenses, amounted to KUSD 4 (2019: KUSD 4 and 2018: KUSD 7). Services provided to the Company There were no services provided to the Company during 2020 by related parties. Auven affiliated companies incurred expenses on behalf of the Company, relating to a telecommunication contract with a third-party vendor, and recharged these at cost. The costs incurred are recognized as G&A expenses and amounted to KUSD 11 in 2019 and KUSD 38 in 2018. Other transactions with related parties Of the 597,774 shares surrendered by Share Purchase Plan 2013 and Share Purchase Plan 2016 participants to settle share purchase plan promissory notes on April 15, 2020 (see note 23, “Share capital”), 556,799 were surrendered by related parties. Of the 4,777,996 shares issued by way of capitalization of reserves on April 16, 2020 (see note 23, “Share capital”), 1,222,966 shares were issued to related parties. Out of the 3,687,500 class E shares issued in 2019, 809,107 shares were purchased by related parties. Shares were issued to and repurchased at the same price from a related party in September 2019 in order to have available treasury shares to meet the demand for shares when share options are exercised. In connection with the Company’s IPO, HPWH TH AG purchased 950,000 shares on the same terms as other investors. In connection with the Company’s follow-on offering Auven Therapeutics GP Ltd., through A.T. Holdings II Sàrl and ADC Products Switzerland Sàrl (“the Selling Shareholders”) granted to the underwriters an option to purchase up to 900,000 additional common shares at the public offering price of USD 34.00 per share, less underwriting discounts and commissions. On October 9, 2020, the underwriters exercised in full their option to purchase an additional 900,000 common shares from the Selling Shareholders at a price of USD 34.00, less underwriting discounts and commissions. The Company did not receive any proceeds or incur any costs related to the sale of these shares by the Selling Shareholders. The Selling Shareholders incurred all costs in addition to underwriting fees and commissions. Chairman’s equity awards The Company granted the Chairman, Mr. Squarer, options to acquire 1,125,545 common shares at USD 18.75 per share in connection with his election to the Board of Directors, representing approximately 2% of our then-outstanding share capital. These options are scheduled to vest upon Mr. Squarer’s continued service through designated dates over a three-year period, or immediately upon a change in control. In accordance with its agreement with Mr. Squarer, the Company provided Mr. Squarer with an additional grant of 341,403 options on June 4, 2020 with an exercise price equal to the fair market value of the Company’s shares on that date, to bring Mr. Squarer’s total rights to acquire the Company’s shares to 2% of the then-outstanding share capital (measured without consideration of the shares underlying these grants). Related party balances at year-end There were no trade accounts payable with related parties at December 31, 2020. Trade accounts payable at December 31, 2019, include amounts payable to Auven companies amounting to KUSD 1. There were no trade accounts receivable with related parties at both December 31, 2020 and December 31, 2019. Key management compensation Key management compensation was: (in KUSD) Year ended December 31, 2020 Year ended December 31, 2019 Year ended December 31, 2018 Salaries and other short-term employee benefits 7,690 5,364 4,512 Pension costs 455 407 299 Share-based compensation expenses 16,752 396 341 Other compensation 196 73 183 25,093 6,240 5,335

Loss per share

Loss per share	12 Months Ended
	Dec. 31, 2020
Earnings per share [abstract]
Loss per share	Loss per share The basic loss per share is calculated by dividing the net loss attributable to shareholders by the weighted average number of shares in issue during the period, excluding common shares owned by the Company and held as treasury shares, as follows: For the Years Ended December 31, (in KUSD, except per share amounts) 2020 2019 2018 Net loss attributable to shareholders (246,290) (116,484) (123,096) Weighted average number of shares in issue (1) 65,410,292 49,279,961 46,600,000 Basic and diluted loss per share (in USD) (3.77) (2.36) (2.64) (1) Share data have been revised to give effect to the share split and share consolidation as explained in note 2 (iv) and note 2 (v), respectively as all Class B, C, D and E preferred shares were converted into common shares upon the completion of the IPO, loss per share data are presented on that basis for all periods. For the years ended December 31, 2020, 2019 and 2018, basic and diluted loss per share are calculated on the weighted average number of shares issued and outstanding and exclude shares to be issued under the 2019 Equity Incentive Plan and the conversion of the principal amount of the convertible loans into the Company’s common shares (see note 22, “Share-based compensation expense and note 21, “Convertible loans”), as the effect of including those shares would be anti-dilutive. Potentially dilutive securities that were not included in the diluted per share calculations because the effect of including them would be anti-dilutive were as follows: For the Years Ended December 31, 2020 2019 2018 Incentive Plan 2014 — 2,074,996 1,959,782 Share Purchase Plan 2016 — 2,784,918 2,369,521 2019 Equity Incentive Plan - Share Options 2,904,673 61,506 — 2019 Equity Incentive Plan - RSUs 63,281 — — Conversion of the principal amount of convertible loans into the Company's common shares 1,665,465 — — 4,633,419 4,921,420 4,329,303

Foreign currency exchange rate

Foreign currency exchange rate	12 Months Ended
	Dec. 31, 2020
Effects Of Changes In Foreign Exchange Rates [Abstract]
Foreign currency exchange rate	Foreign currency exchange rate The following exchange rates have been used for the translation of the financial statements of ADCT UK, the functional currency of which is the British pound: USD / GBP Year ended December 31, 2020 Year ended December 31, 2019 Year ended December 31, 2018 Closing rate, GBP 1 1.36501 1.3186 1.2690 Weighted average exchange rate, GBP 1 1.28423 1.2747 1.3501

Events after reporting period

Events after reporting period	12 Months Ended
	Dec. 31, 2020
Events After Reporting Period [Abstract]
Events after the reporting date	Events after the reporting dateThe Company has evaluated its subsequent events through March 18, 2021, the date the financial statements were available to be issued, and has concluded that there are no subsequent events requiring disclosure in the financial statements other than those described below. As the Company continues to grow its operations, prepares for product commercialization and further develops its pipeline, it is looking to expand its facilities. During the first quarter of 2021, the Company entered into a new lease agreement with a ten-year term commencing in January 2021 for space in the iHub building on the Imperial University college campus in White City, West London. The primary function of the new facility, which consists of approximately 1,100m 2

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies, Changes In Accounting Estimates And Errors [Abstract]
Compliance with International Financial Reporting Standards	Compliance with International Financial Reporting StandardsThe ADCT Group consolidated financial statements have been prepared in accordance with International Financial Reporting Standards (IFRS) as issued by the International Accounting Standards Board (IASB). As of December 31, 2020, the financial statements are presented in thousand dollars (KUSD).
Historical Cost Convention	Historical Cost ConventionThe consolidated financial statements have been prepared under the historical cost convention, except for the defined benefit pension liabilities, where plan assets are measured at fair value, and the embedded derivative conversion feature and the derivative associated with the convertible loans (see note 21 “Convertible loans”), which are measured at fair value.
Going concern basis	Going concern basis ADCT is a late clinical-stage company developing innovative therapeutics. The Group is exposed to all risks inherent in establishing and developing its business, including the substantial uncertainty that current projects will succeed. The Group's success may also depend on its ability to: • establish and maintain a strong patent position and protection; • develop, gain regulatory approval and commercialize drug products; • enter into collaborations with partners in the pharmaceutical industry; • acquire and retain key personnel; and • acquire additional funding to support its operations. Since its incorporation, the Group has primarily funded its growth through capital increases, both equity and debt, and additional funds provided by research collaborations. During the 2020 fiscal year, the Company issued common shares through an initial public and follow-on offering (see note 2(vi) and 2(vii)) and the issuance of convertible loans (see note 21, “Convertible loans”). The Group does not have recourse to bank loans. As a result, the Group is not exposed to liquidity risk through requests for early repayment of loans, other than, pursuant to the convertible loans, it must maintain a balance of at least USD 50 million in cash and cash equivalents at the end of each quarter. As of December 31, 2020, the Group’s cash and cash equivalents amounted to KUSD 439,195 (December 31, 2019: KUSD 115,551).
Consolidation	ConsolidationThe annual closing date of the individual financial statements is December 31. Subsidiaries are all entities over which the Company has control. The Company controls an entity when the Company is exposed to, or has rights to, variable returns from its involvement with the entity and has the ability to affect those returns through its power over the entity. Subsidiaries are fully consolidated from the date on which control is transferred to the Company. They are de-consolidated from the date that control ceases. All intercompany transactions have been eliminated.
Foreign currency translation	Foreign currency translation Functional and presentation currency Items included in the financial statements of each of the Group entities are measured using the currency of the primary economic environment in which the entity operates (“the functional currency”). The consolidated financial statements are presented in US dollars (“USD” or “Dollars”), which is the Company’s functional and Group’s presentation currency. Transactions and balances Foreign currency transactions are translated into the functional currency using the exchange rates prevailing at the dates of the transactions. Foreign exchange gains and losses resulting from the settlement of such transactions and from the translation at year-end exchange rates of monetary assets and liabilities denominated in foreign currencies are recognized in Consolidated Statement of Operation. All foreign exchange gains and losses are presented in the Consolidated Statement of Operation within “Exchange differences”. Group companies The results and financial position of all the Group entities that have a functional currency different from the presentation currency are translated into the presentation currency as follows: (i) assets and liabilities for each balance sheet presented are translated at the closing rate at the date of that balance sheet; (ii) income and expenses for each Consolidated Statement of Operation are translated at monthly average exchange rates; and (iii) all resulting exchange differences are recognized in other comprehensive loss, under “Cumulative translation adjustments”.
Cash and cash equivalents	Cash and cash equivalentsCash and cash equivalents includes cash on hand, deposits held at call with external financial institutions and other short-term highly liquid investments with original maturities to the Company of three months or less. They are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Any bank overdrafts are not netted against cash and cash equivalents but are shown as part of current liabilities on the Consolidated Balance Sheet.
Inventory	InventoryThe Company assessed its accounting policy for inventory costs, with the Company’s submission of its biologics license application (“BLA”) to the U.S. Food and Drug Administration (“FDA”) for Lonca for the treatment of relapsed or refractory diffuse large B-cell lymphoma (“DLBCL”). The Company believes that capitalization of inventory costs associated with certain products prior to regulatory approval of such products, or for inventory produced in new production facilities, is appropriate when management considers it highly probable that pre-approval inventory costs will be recoverable through future sales of the drug product. The determination to capitalize is based on the particular facts and circumstances relating to the expected regulatory approval of the product or production facility being considered and, accordingly, the time frame within which the determination is made varies from product to product. The assessment of whether or not the product is considered highly probable to be saleable will be made on a quarterly basis and includes, but is not limited to, how far a particular product or facility has progressed along the approval process, any known safety or efficacy concerns, potential labeling restrictions and other impediments. As of December 31, 2020, the Company believes it is highly probable that it will receive regulatory approval for Lonca. Accordingly, such costs incurred to manufacture pre-approved product would qualify to be capitalized as inventory. However, the Company has written-down such inventory costs incurred related to the manufacture of Lonca to a net realizable value of zero. The impairment charge has been recorded as research and development expense because of the inherent risks associated with the development of a product candidate, uncertainty about the regulatory approval process, including the expected dating of Lonca at the time of launch, as well as the timing of the associated commercial launch and market size for the drug candidate, and lack of history for the Company’s ability to obtain regulatory approval for drug candidates. The Company anticipates that it will reverse impairments resulting from the write-down of its inventory to a net realizable value of zero upon receiving regulatory approval of Lonca based on a number of factors including the existence of inventory on hand and estimated demand as well as the expiration of such product.
Property, plant and equipment	Property, plant and equipmentAll property, plant and equipment is stated at historical cost less accumulated depreciation. Historical cost includes expenditure that is directly attributable to the acquisition of the items.
Intangible assets	Intangible assets Licenses Licenses acquired are capitalized as intangible assets at historical cost. Licenses with definite-useful lives are amortized over their useful lives, which are determined on a basis of the expected pattern of consumption of the expected future economic benefits embodied in the licenses and which therefore commence only once the necessary regulatory and marketing approval has been received. Prior to regulatory and marketing approval, licenses are treated as indefinite-lived assets and not amortized. These licenses are tested annually for impairment in the last quarter of each fiscal year and more frequently if events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. Amortization and impairment of licenses Prior to regulatory and marketing approval, impairment of indefinite-lived licenses is charged to research and development expenses. Subsequent to regulatory and marketing approval, amortization of licenses will be charged to cost of goods sold. See note 16, “Intangible assets” for further information.
Investments in joint ventures	Investments in joint venturesA joint venture is a joint arrangement whereby the parties that have joint control of the arrangement have rights to the net assets of the joint arrangement. Joint control is the contractually agreed sharing of control of an arrangement, which exists only when decisions about the relevant activities require unanimous consent of the parties sharing control. An investment in a joint venture is accounted for using the equity method from the date on which the investee becomes a joint venture. Under the equity method, an investment in a joint venture is recognized initially in the Consolidated Balance Sheet at cost and adjusted thereafter to recognize the Company’s share of the profit or loss, other comprehensive income or loss of the joint venture, distributions from the joint venture and other adjustments to the Company’s proportionate interest in the joint venture. The Company’s initial investment is recorded as an Interest in joint venture in the Consolidated Balance Sheet. The Company’s proportionate share of net income or losses of equity investments is included within Share of results with joint venture in the Consolidated Statement of Operation. The Company’s carrying value of its investment in a joint venture increases or decreases in relation to the Company’s proportionate share of comprehensive income or loss of the joint venture. When the Company’s share of losses of a joint venture exceeds the Company’s interest in that joint venture less the carrying value of the deferred gain described below, the Company ceases to recognize its share of further losses. Additional losses are recognized only to the extent that the Company has incurred legal or constructive obligations or made payments on behalf of the joint venture. In connection with the Company’s initial investment, the gain resulting from the transaction was only recognized to the extent of the unrelated investors’ equity interest in the joint venture, which resulted in a deferred gain for a portion of the Company’s initial investment. The Company will begin to recognize the deferred gain upon the commercialization of any or all the licensed intellectual property by the joint venture. The deferred gain will be recognized over the estimated commercialization period in which a licensed product is developed and approved using a systematic approach that approximates the pattern of consumption of the licensed intellectual property by the joint venture. Investments accounted for under the equity method are assessed for potential impairment on a regular basis based on qualitative factors.
Impairment of non-financial assets	Impairment of non-financial assetsNon-financial assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. An impairment loss is recognized for the amount by which the asset's carrying amount exceeds its recoverable amount. The recoverable amount is the higher of an asset's fair value less costs of disposal and value in use. In assessing value in use, the estimated future cash flows, adjusted for the risks specific to each asset, are discounted to their present value using a discount rate that reflects current market assessments of the time value of money and the general risks affecting the pharmaceutical industry. For the purpose of impairment testing, assets are grouped together into the smallest group of assets that generate cash inflows from continuing use that are largely independent of the cash flows of other assets (“cash-generating units”). Impairment losses are recognized in the Consolidated Statement of Operation. Prior impairments of non-financial assets are reviewed for possible reversal of the impairment at each reporting date.
Employee benefits	Employee benefits Employee Benefit Programs Group companies operate defined benefit and defined contribution pension schemes in accordance with the local conditions and practices in the countries in which they operate. The defined benefit schemes are generally funded through payments to insurance companies or trustee-administered funds, determined by periodic actuarial calculations. A defined contribution plan is a pension plan under which the Group pays fixed contributions into a separate entity (a fund) and has no legal or constructive obligations to pay further contributions if the fund does not hold sufficient assets to pay all employees the benefits relating to employee service in the current and prior periods. A defined benefit plan is a pension plan that is not a defined contribution plan. Typically, defined benefit plans define an amount of pension benefit that an employee will receive on retirement, usually dependent on one or more factors such as age, years of service and compensation. However, as is the case with many Swiss pension plans, although the amount of ultimate pension benefit is not defined, certain legal obligations of the plan nevertheless create constructive obligations on the employer to pay further contributions to fund an eventual deficit. This results in the plan being accounted for as a defined benefit plan. The liability recognized in the balance sheet in respect of defined benefit pension plans is the present value of the defined benefit obligation at the end of the reporting period less the fair value of plan assets. The defined benefit obligation is calculated annually by independent actuaries using the projected unit credit method. The present value of the defined benefit obligation is determined by discounting the estimated future cash outflows using interest rates of high-quality corporate bonds that are denominated in the currency in which the benefits will be paid, and that have terms to maturity that approximate the terms of the related pension obligation. The current service cost of the defined benefit plan, recognized in the Consolidated Statement of Operation in employee benefit expenses, except where included in the cost of an asset, reflects the increase in the defined benefit obligation resulting from employee service in the current year. Past service costs, resulting from a plan amendment or curtailment, are recognized immediately in the Consolidated Statement of Operation. The net interest cost is calculated by applying the discount rate to the net balance of the present value of the defined benefit obligation and the fair value of plan assets. This cost is included in employee benefit expenses in the Consolidated Statement of Operation. Actuarial gains and losses arising from experience adjustments and changes in actuarial assumptions are charged or credited to equity within the Consolidated Statement of Other Comprehensive Loss in the period in which they arise. For defined contribution plans, the company pays contributions to publicly or privately administered pension insurance plans on a mandatory, contractual or voluntary basis. Once the contributions have been paid, the company has no further payment obligations. The contributions are recognized as employee benefit expenses in the Consolidated Statement of Operation. Prepaid contributions are recognized as an asset to the extent that a cash refund or a reduction in the future payments is available. See note 20, “Pension obligations” for further information. Share-based compensation expense The fair value of shares or options granted, respectively, under share purchase or share option plans is recognized as an employee share-based compensation expense with a corresponding increase in equity. The total amount to be expensed is determined by reference to the fair value of the shares or options granted: – including any market performance conditions; – excluding the impact of any service and non-market performance vesting conditions; and – including the impact of any non-vesting conditions. The total expense is recognized over the vesting period, which is the period over which all of the specified vesting conditions are to be satisfied. At the end of each period, the entity revises its estimate of the number of options that are expected to vest based on the non-market vesting and service conditions. It recognizes the impact of the revision to original estimate, if any, within the Consolidated Statement of Operation, with a corresponding adjustment to equity. The proceeds received upon the exercise of options are net of any directly attributable transaction costs and are credited directly to equity.
Share capital and share premium	Share capital and share premium Share capital The Company has issued one class of common shares, which is classified as equity (see note 23, “Share Capital”). Share premium Amounts of contribution in excess of par value are accounted for as share premium. Share premium also arises from additional capital contributions from shareholders. Incremental costs directly attributable to equity transactions such as the issue of new capital shares are shown in equity as a deduction, net of tax, from the proceeds within share premium. Transaction costs that relate to equity and non-equity transactions are allocated to those transactions using a basis of allocation that is rational and a consistent methodology with previous transactions.
Treasury shares	Treasury sharesTreasury shares are recognized at acquisition cost and deducted from shareholders’ equity at the time of acquisition, until they are cancelled. Where such shares are subsequently sold, any consideration received is included in shareholders’ equity.
Leases	Leases This policy concerns instances where a Group company is the lessee. Leases are recognized as a right-of-use asset and a corresponding liability at the date at which the leased asset is available for use by the group. Each lease payment is allocated between the liability and the finance cost. The finance cost is charged to the Consolidated Statement of Operation over the lease period so as to produce a constant periodic rate of interest on the remaining balance of the liability for each period. The right-of-use asset is depreciated over the shorter of the asset’s useful life and the lease term on a straight-line basis. The lease payments are discounted using the interest rate implicit in the lease. If that rate cannot be determined, the lessee’s incremental borrowing rate is used, being the rate that the lessee would have to pay to borrow the funds necessary to obtain an asset of similar value in a similar economic environment with similar terms and conditions. Right-of-use assets are measured at cost comprising the following: – the amount of the initial measurement of lease liability; – any lease payments made at or before the commencement date less any lease incentives received; – any initial direct costs, and – restoration costs. The lease term is considered to be the non-cancellable period of a lease, together with both: – periods covered by an option to extend the lease if the Company is reasonably certain to exercise that option; and – periods covered by an option to terminate the lease if the Company is reasonably certain not to exercise that option. Assumptions as to whether the Company is reasonably likely to exercise any extension or termination options have been individually assessed based on the Company’s plans. The policy of recognizing right-of-use assets and lease liabilities is not applied to short-term (under 12 months) or low value leases. For deferred tax purposes, the Group considers the net effect of temporary differences arising from the right-of-use asset and the lease liabilities. In 2018 and prior years, leases in which a significant portion of the risks and rewards of ownership are retained by the lessor were classified as operating leases. Payments made under operating leases (net of any incentives received from the lessor) were charged to the Consolidated Statement of Operation on a straight-line basis over the period of the lease.
Convertible loans	Convertible loans The Company entered into a USD 115.0 million Facility Agreement (the “Facility Agreement”) (see note 21, “Convertible loans”) on April 24, 2020, pursuant to which the counterparty agreed to extend senior secured convertible term loans to the Company in two separate disbursements: (i) an initial disbursement of convertible loans in the amount of USD 65.0 million upon the completion of the IPO, and satisfaction of certain other conditions (the “first tranche”) and (ii) a subsequent disbursement of convertible loans in the amount of USD 50.0 million upon the receipt of regulatory approval for Lonca, and satisfaction of certain other conditions (the “second tranche”). Accounting for the first tranche On May 19, 2020, the Company received convertible loans in the amount of USD 65.0 million upon completion of the IPO. These convertible loans have been recognized as a hybrid financial instrument and accounted for as two separate components: (i) a loan and (ii) an embedded conversion option derivative. (i) The embedded conversion option derivative was initially measured at fair value and is subsequently remeasured to fair value at each reporting date. Under IAS 32, this derivative could have been classified as a component of equity only if in all cases the contract would be settled by the Company delivering a fixed number of its own equity instruments in exchange for a fixed amount of cash or debt redemption. However, the agreement foresees, in the event of a major transaction, the payment of “make-whole” amounts that would have to be computed in the light of the circumstances and are therefore not fixed. As a result, the derivative is presented in the balance sheet as a liability and classified as non-equity in accordance with IFRS 9 and IAS 32. Changes in the fair value (gains or losses) of the derivative at the end of each period are recorded in the Consolidated Statement of Operation. (ii) The convertible loan’s initial fair value is the residual amount of the consideration received, net of attributable costs, after separating out the fair value of the embedded conversion option derivative. The loan is subsequently measured at its amortized cost in accordance with IFRS 9. It is presented as a financial liability in the Consolidated Balance Sheet. Expenses and fees payable upon the issuance of the first tranche of convertible loans were allocated pro rata to the above two components. The share of expenses allocated to the embedded conversion option derivative was charged directly to the Consolidated Statement of Operation, while the share of expenses allocated to the residual convertible loan was deducted from the loan. Accounting for the second tranche The Company is obligated to draw down the second tranche in the amount of USD 50.0 million upon receipt of regulatory approval for Lonca. However, the second tranche will automatically terminate if the Company has not received the regulatory approval on or prior to December 31, 2021. This obligation has been accounted for as a derivative, and presented in the Consolidated Balance Sheet as a financial liability. Changes in the fair value (gains or losses) of the derivative at the end of each period are recorded in the Consolidated Statement of Operation.
Revenue recognition	Revenue recognition To date, the Company has not generated any revenue from the sale of its product candidates. Revenue is measured at the fair value of the consideration received or receivable for the sale of services in the ordinary course of the Group’s activities. Revenue is shown net of value-added tax, rebates and discounts and after eliminating sales within the Group. The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company applies the five-step model to contracts only when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract, determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Performance obligation satisfied to the state of completion - deferred contract revenue amortization When the outcome of a transaction involving the rendering of services can be estimated reliably, revenue is recognized according to the stage of completion of the transaction at the end of the period using the cost input method. Under this method, revenue is recognized in the accounting periods in which the services are rendered. The recognition of revenue on this basis provides full information on the extent of service activity and performance during a period. To be able to estimate the outcome of a transaction reliably, the entity must be able to make a reliable estimate of total transaction revenue, the stage of completion and the costs to complete the transaction. The stage of completion is determined as the proportion of the transaction costs incurred for services rendered to date compared to the estimated total transaction costs.
Research and development (R&D) expenses	Research and development (“R&D”) expensesResearch expenditure is recognized in expense in the year in which it is incurred. Internal development expenditure is capitalized only if it meets the recognition criteria of IAS 38 “Intangible Assets”. Where regulatory and other uncertainties are such that the criteria are not met, which is almost invariably the case prior to approval of the drug by the relevant regulatory authority, the expenditure is recognized in the Consolidated Statement of Operation. When certain criteria are met, the Company may capitalize and amortize on a straight-line basis over its estimated useful life, internal development expenditures. To date, the Company has not capitalized any R&D expenses.
Selling and marketing ("S&M") expenses	Selling and marketing (“S&M”) expensesS&M expense is expensed when incurred and include employee expenses (including share-based compensation expense) for commercial employees, external costs related to commercialization (including professional fees, communication costs and IT costs and travel expenses). To date, depreciation expense and facility expense has not been material.
General and administrative ("G&A") expenses	General and administrative (“G&A”) expensesG&A expense is expensed when incurred and include employee expenses (including share-based compensation expense) for G&A employees, external costs (including in particular professional fees, communications costs and IT costs, facility expenses and travel expenses), G&A costs charged by related parties (including telecommunications costs), depreciation of property, plant and equipment, depreciation of right-of-use assets and amortization of intangible assets.
Current, deferred income tax and tax credit	Current, deferred income tax and tax credit The tax expense for the period comprises current and deferred tax. Tax is recognized in the Consolidated Statement of Operation, except to the extent that it relates to items recognized in other comprehensive loss or directly in equity; in this case the related tax is recognized in other comprehensive loss or directly in equity, respectively. The current income tax charge is calculated on the basis of the tax laws enacted or substantively enacted at the balance sheet date in the countries where the Company and its subsidiaries operate and generate taxable income. Management periodically evaluates positions taken in tax returns with respect to situations in which applicable tax regulation is subject to interpretation. It establishes provisions where appropriate on the basis of amounts expected to be paid to the tax authorities. Taxes on income are accrued in the same periods as the revenues and expenses to which they relate. Current income tax assets and liabilities for the current period are measured at the amount expected to be recovered from or paid to the taxation authorities. Deferred income tax is recognized, using the liability method, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the Consolidated Financial Statements. However, deferred tax liabilities are not recognized if they arise from the initial recognition of goodwill. The deferred income tax is not accounted for if it arises from initial recognition of an asset or liability in a transaction other than a business combination that at the time of the transaction affects neither accounting nor taxable profit or loss. Deferred income tax is determined using tax rates (and laws) that have been enacted or substantively enacted by the balance sheet date and are expected to apply when the related deferred income tax asset is realized or the deferred income tax liability is settled. Deferred income tax assets are recognized only to the extent that it is probable that future taxable profit will be available against which the temporary differences or the unused tax losses can be utilized. Deferred income tax assets from tax credit carryforwards are recognized to the extent that the national tax authority confirms the eligibility of such a claim and that the realization of the related tax benefit through future taxable profits is probable. Deferred income tax assets and liabilities are offset when there is a legally enforceable right to offset current tax assets against current tax liabilities and when the deferred income tax assets and liabilities relate to income taxes levied by the same taxation authority on either the same taxable entity or different taxable entities where there is an intention to settle the balances on a net basis.
Loss per share	Loss per shareBasic loss per share is calculated by dividing the net loss attributable to shareholders by the weighted average number of common shares in issue during the year, excluding common shares owned by the Company and held as treasury shares. See note 27, “Loss per share.”Diluted loss per share adjusts the shares used in the determination of basic loss per share to take into account the after-tax effect of interest and other financing costs associated with potentially dilutive common shares, if applicable, and the weighted average number of ordinary shares that would have been outstanding assuming the conversion of all dilutive potential ordinary shares (share option plans and convertible loans). See note 22, “Share-based compensation expense” and note 21, “Convertible loans”, respectively.
Segment reporting	Segment reporting The Company is managed and operated as one business. A single management team that reports to the chief executive officer comprehensively manages the entire business. Accordingly, the Company views its business and manages its operations as one operating segment. Revenue is attributable to the Company’s country of domicile, Switzerland. The Company has locations in three regions: Switzerland, the United Kingdom and the United States. An analysis of non-current assets by geographic region is presented in note 13, “Non-current assets by geographic area”.
New, amended, and recently adopted IFRS standards	New and amended IFRS standards There are no new IFRS standards, amendments to standards or interpretations that are mandatory for the financial year beginning on January 1, 2020, that are relevant to the Group and that have had any impact in the interim periods. New standards, amendments to standards and interpretations that are not yet effective, which have been deemed by the Group as currently not relevant, and hence are not listed here. (ii) Recently adopted IFRS standards IFRS 16 “Leases” has been adopted by the Group from January 1, 2019. Under IAS 17, lessees were required to make a distinction between a finance lease (on balance sheet) and an operating lease (off balance sheet). IFRS 16 now requires lessees to recognize an asset, being the right to use the leased item, and a financial liability, reflecting future lease payments, for virtually all lease contracts, though there is an optional exemption for certain short-term leases and leases of low-value assets. The Group has applied the modified retrospective approach, which requires the recognition of the cumulative effect of initially applying IFRS 16 as of January 1, 2019 to accumulated losses without restating prior years. Since the Group recognized the right-of-use assets at an amount equal to the lease liabilities there was no impact on accumulated losses. The new accounting policy for leases is set out in note 3.12, “Leases”.

Basis of preparation (Tables)

Basis of preparation (Tables)	12 Months Ended
	Dec. 31, 2020
Corporate Information And Statement Of IFRS Compliance [Abstract]
Schedule of movement in interest in joint venture	(in KUSD) Interest in joint venture January 1, 2020 — Initial investment 48,040 Share of results with joint venture (132) December 31, 2020 47,908
Summary of financial information in joint venture	The tables below provide summarized financial information for Overland ADCT BioPharma that are material to the Company. The following information reflects the amounts presented in the financial statements of Overland ADCT BioPharma and not the Company’s share of those amounts. Summarized Balance Sheet As of December 31, 2020 Cash and cash equivalents 50,000 Intangible assets 48,040 Total liabilities 269 Net assets 97,771 Summarized Statement of Comprehensive Loss For the period from December 14, 2020 through December 31, 2020 Operating expenses 269 Net loss 269

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies, Changes, Accounting Estimates And Errors [Abstract]
Schedule of property, plant and equipment useful lives	Depreciation is calculated using the straight-line method to reduce the cost of each asset to its residual value over its estimated useful life, as follows: Leasehold improvements 3 to 10 years Laboratory equipment 5 years Office equipment 5 years Hardware 3 years (in KUSD) Leasehold Laboratory Office Hardware Construction in progress Total Cost January 1, 2019 514 939 597 497 — 2,547 Additions 17 131 93 118 — 359 Exchange difference 2 41 8 3 — 54 December 31, 2019 533 1,111 698 618 — 2,960 Additions 224 30 84 616 67 1,021 Disposals and scrapping (13) (178) (117) (367) — (675) Exchange difference 2 39 6 3 — 50 December 31, 2020 746 1,002 671 870 67 3,356 Accumulated depreciation January 1, 2019 (126) (310) (245) (326) — (1,007) Depreciation charge (82) (204) (149) (117) — (552) Exchange difference (1) (19) (3) (2) — (25) December 31, 2019 (209) (533) (397) (445) — (1,584) Depreciation charge (162) (207) (173) (232) — (774) Disposals and scrapping 13 178 117 367 — 675 Exchange difference (4) (32) (4) (4) — (44) December 31, 2020 (362) (594) (457) (314) — (1,727) Net book amount December 31, 2019 324 578 301 173 — 1,376 December 31, 2020 384 408 214 556 67 1,629 Depreciation of property, plant and equipment has been charged to the following categories in the Consolidated Statement of Operation: Year Ended December 31, (in KUSD) 2020 2019 2018 R&D expense 589 407 330 G&A expense 185 145 158 774 552 488

New and amended IFRS standards

New and amended IFRS standards (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies, Changes In Accounting Estimates And Errors [Abstract]
Reconciliation of operating lease obligations under previous accounting policy as compared to initial application of IFRS 16	The following table reconciles the Group's operating lease obligations at December 31, 2018, as computed under the Group's previous accounting policy disclosed above in note 3.12, “Leases”, with the lease obligations recognized on initial application of IFRS 16 at January 1, 2019. (in KUSD) Operating lease commitments at December 31, 2018 4,378 Discounted at the incremental borrowing rate as at January 1, 2019 3,976 Short-term leases recognized on a straight-line basis as expenses (15) Low-value leases recognized on a straight-line basis as expenses — Extension options reasonably certain to be exercised 1,462 Lease obligations recognized at January 1, 2019 5,423 Of which are: Lease liabilities (short-term) 924 Lease liabilities (long-term) 4,499

Financial risk management (Tabl

Financial risk management (Tables)	12 Months Ended
	Dec. 31, 2020
Financial Instruments [Abstract]
Schedule of cash and cash equivalents	The Group's cash and cash equivalents are denominated in the following currencies: 2020 2020 2019 2019 December 31 in KL/C (1) in KUSD in KL/C (1) in KUSD In USD 435,750 435,750 109,939 109,939 In CHF 376 426 457 472 In GBP 2,096 2,861 3,529 4,654 In EUR 129 158 433 486 439,195 115,551 _______________ (1) Thousands Local Currencies
Schedule of financial liabilities	The table below analyses the Group's financial liabilities into relevant maturity groupings based on the remaining period at the balance sheet date to the contractual maturity date. (in KUSD) Note Less than 1-3 3-5 More than Trade accounts payable 5,279 — — — Lease liabilities, contractual rent 15 1,050 1,047 642 903 Convertible loan, interest and exit fee 21 3,921 7,842 7,703 — Convertible loan, principal (1) 21 — — 65,000 — At December 31, 2020 10,250 8,889 73,345 903 Trade accounts payable 3,329 — — — Lease liabilities, contractual rent 15 1,246 1,859 2,265 — At December 31, 2019 4,575 1,859 2,265 — (1) Amount represents the principal amount of the convertible loan due May 2025 associated with the first tranche of the Facility Agreement. See note 21, “Convertible loans”. In addition, the Facility Agreement contains a second tranche of USD 50.0 million that the Company is obligated to draw down upon the receipt of regulatory approval of Lonca. While the Company believes that it is highly probable that regulatory approval will be obtained, such amount has not been included in the table above as the amount has not been drawn down as of December 31, 2020.

Other income (expense) (Tables)

Other income (expense) (Tables)	12 Months Ended
	Dec. 31, 2020
Analysis of income and expense [abstract]
Schedule of Other income (expense)	Year Ended December 31, (in KUSD) Note 2020 2019 2018 Other income 584 1,655 — Convertible loans, derivatives, change in fair value (expense) 21 (45,411) — — Convertible loans, first tranche, derivative, transaction costs 21 (1,571) — — Share of results with joint venture 2 (viii) 24,368 — — Financial income 832 2,253 2,856 Financial expense (4,926) (156) — Exchange differences (loss) gain (576) (255) 213 Total other (expense) income (26,700) 3,497 3,069

Employee expenses (Tables)

Employee expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Analysis of income and expense [abstract]
Schedule of Employee expenses	Year Ended December 31, (in KUSD) Note 2020 2019 2018 Wages, salaries and other costs 44,058 24,061 19,245 Social security costs 7,292 3,871 3,452 Share-based compensation expense 22 42,928 1,117 469 Defined benefit plan costs 20 966 462 535 Defined contribution plan costs 727 540 481 Employee expenses 95,971 30,051 24,182

Expenses by nature (Tables)

Expenses by nature (Tables)	12 Months Ended
	Dec. 31, 2020
Analysis of income and expense [abstract]
Schedule of Expenses by nature	The following table provides the Consolidated Statement of Operation classification of our expense by nature: Year Ended December 31, (in KUSD) Note 2020 2019 2018 R&D External costs (1) 97,768 82,621 99,067 Employee expenses (2) 9 44,264 24,916 19,246 R&D expense 142,032 107,537 118,313 S&M External costs 11,887 — — Employee expenses (2) 9 10,214 — — S&M expense 22,101 — — G&A External costs (1) 13,637 9,067 3,832 Employee expenses (2) 9 41,493 5,135 4,936 G&A expense 55,130 14,202 8,768 Total operating expense 219,263 121,739 127,081 (1) Includes depreciation expense; Depreciation expense for S&M was not material. (2) Includes share-based compensation expense

Income tax expense (Tables)

Income tax expense (Tables)	12 Months Ended
	Dec. 31, 2020
Income Taxes [Abstract]
Disclosure Of Major Components Of Tax Expense (Income)	Year Ended December 31, (in KUSD) 2020 2019 2018 Current income taxes for the year 417 572 218 Current income taxes related to prior years (90) 10 6 Income tax expense 327 582 224
Disclosure Of Reconciliation Of Accounting Profit Multiplied By Applicable Tax Rates	The tax on the Group's net loss before tax differs from the theoretical amount that would arise using the weighted average applicable tax rate as follows: Year Ended December 31, (in KUSD) 2020 2019 2018 Loss before taxes 245,963 115,902 122,872 Tax calculated at tax domestic rates applicable to profits in the respective countries (33,319) (12,332) (13,321) Tax effects of: - Tax losses for which no deferred income tax asset was recognized 26,112 13,187 13,766 - Utilization of R&D tax credit (USA) (546) (436) (310) - Income not subject to tax / (expenses not deductible for tax purposes) 8,166 156 83 - Tax relating to prior years (90) 10 6 - Other 4 (3) — Income tax expense 327 582 224

Other current assets (Tables)

Other current assets (Tables)	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Schedule of Other Current Assets	(in KUSD) December 31, 2020 December 31, 2019 VAT receivable, net 453 471 Withholding tax receivable 991 626 Prepaid insurance 2,852 — Prepaid compensation 1,488 — Prepaid expenses - other 3,815 4,215 UK R&D expenditure credit receivable 1,246 891 Other 410 852 11,255 7,055

Non-current assets by geograp_2

Non-current assets by geographic area (Tables)	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Schedule of Non-current assets by geographic area	(in KUSD) Country December 31, 2020 December 31, 2019 Switzerland 60,231 10,903 United Kingdom 1,132 2,032 United States 1,482 1,773 62,845 14,708

Property, plant and equipment (

Property, plant and equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property, plant and equipment [abstract]
Schedule of property, plant and equipment useful lives	Depreciation is calculated using the straight-line method to reduce the cost of each asset to its residual value over its estimated useful life, as follows: Leasehold improvements 3 to 10 years Laboratory equipment 5 years Office equipment 5 years Hardware 3 years (in KUSD) Leasehold Laboratory Office Hardware Construction in progress Total Cost January 1, 2019 514 939 597 497 — 2,547 Additions 17 131 93 118 — 359 Exchange difference 2 41 8 3 — 54 December 31, 2019 533 1,111 698 618 — 2,960 Additions 224 30 84 616 67 1,021 Disposals and scrapping (13) (178) (117) (367) — (675) Exchange difference 2 39 6 3 — 50 December 31, 2020 746 1,002 671 870 67 3,356 Accumulated depreciation January 1, 2019 (126) (310) (245) (326) — (1,007) Depreciation charge (82) (204) (149) (117) — (552) Exchange difference (1) (19) (3) (2) — (25) December 31, 2019 (209) (533) (397) (445) — (1,584) Depreciation charge (162) (207) (173) (232) — (774) Disposals and scrapping 13 178 117 367 — 675 Exchange difference (4) (32) (4) (4) — (44) December 31, 2020 (362) (594) (457) (314) — (1,727) Net book amount December 31, 2019 324 578 301 173 — 1,376 December 31, 2020 384 408 214 556 67 1,629 Depreciation of property, plant and equipment has been charged to the following categories in the Consolidated Statement of Operation: Year Ended December 31, (in KUSD) 2020 2019 2018 R&D expense 589 407 330 G&A expense 185 145 158 774 552 488

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Schedule of quantitative information about right-of-use assets	The following tables provide balance sheet classification related to leases: (in KUSD) December 31, 2020 December 31, 2019 Properties (offices) 3,071 4,820 Vehicles 58 78 Total right-of-use assets 3,129 4,898 (in KUSD) Right-of-Use Assets Properties (Offices) Vehicles Total Cost January 1, 2019 5,399 24 5,423 Additions 466 78 544 Disposals — (24) (24) Exchange difference 22 — 22 December 31, 2019 5,887 78 5,965 Modification of lease terms (583) — (583) Exchange difference 20 — 20 December 31, 2020 5,324 78 5,402 Accumulated depreciation January 1, 2019 — — — Depreciation charge (1,051) (13) (1,064) Disposals — 13 13 Exchange difference (16) — (16) December 31, 2019 (1,067) — (1,067) Depreciation charge (1,131) (20) (1,151) Exchange difference (55) — (55) December 31, 2020 (2,253) (20) (2,273) Net book amount December 31, 2019 4,820 78 4,898 December 31, 2020 3,071 58 3,129 Depreciation of right-of-use assets have been charged to the following categories in the Consolidated Statement of Operation: For the Years Ended (in KUSD) 2020 2019 R&D expenses 915 837 G&A expenses 236 227 1,151 1,064
Schedule of quantitative information about lease liabilities	(in KUSD) December 31, 2020 Three Months Ended December 31, 2019 Lease liabilities (short-term) 1,002 1,132 Lease liabilities (long-term) 2,465 3,899 Total lease liabilities 3,467 5,031 (in KUSD) Lease liabilities Properties (Offices) Vehicles Total January 1, 2019 5,399 24 5,423 Additions 466 78 544 Disposals — (12) (12) Cash outflow (including interest) (1,130) (13) (1,143) Interest 140 1 141 Exchange difference 78 — 78 December 31, 2019 4,953 78 5,031 Additions — — — Modification of lease terms (583) — (583) Cash outflow (including interest) (1,227) (22) (1,249) Interest 102 3 105 Exchange difference 157 6 163 December 31, 2020 3,402 65 3,467 December 31, 2019 Lease liabilities (short-term) 1,114 18 1,132 Lease liabilities (long-term) 3,839 60 3,899 Total lease liabilities 4,953 78 5,031 December 31, 2020 Lease liabilities (short-term) 981 21 1,002 Lease liabilities (long-term) 2,421 44 2,465 Total lease liabilities 3,402 65 3,467

Intangible assets (Tables)

Intangible assets (Tables)	12 Months Ended
	Dec. 31, 2020
Intangible Assets [Abstract]
Disclosure of reconciliation of changes in intangible assets and goodwill	(in KUSD) Licenses Software Total Cost January 1, 2019 7,490 87 7,577 Additions 1,731 59 1,790 Exchange difference — 1 1 December 31, 2019 9,221 147 9,368 Additions 1,923 85 2,008 Disposals — (65) (65) Exchange difference — 1 1 December 31, 2020 11,144 168 11,312 Accumulated amortization January 1, 2019 (853) (50) (903) Amortization charge — (30) (30) Exchange difference — (1) (1) December 31, 2019 (853) (81) (934) Amortization charge — (47) (47) Impairment charge (216) — (216) Disposals — 65 65 Exchange difference — (1) (1) December 31, 2020 (1,069) (64) (1,133) Net book amount December 31, 2019 8,368 66 8,434 December 31, 2020 10,075 104 10,179 Amortization and impairment of intangible assets have been charged to the following categories in the Consolidated Statement of Operation: (in KUSD) Year ended December 31, 2020 Year ended December 31, 2019 Year ended December 31, 2018 R&D expenses 230 14 244 G&A expenses 33 16 8 263 30 252

Financial instruments (Tables)

Financial instruments (Tables)	12 Months Ended
	Dec. 31, 2020
Financial Instruments [Abstract]
Schedule of financial assets	The accounting policies for financial instruments have been applied as indicated below: (in KUSD) Note December 31, 2020 December 31, 2019 Financial assets - financial assets Cash and cash equivalents 5.1 / 17b 439,195 115,551 Other current assets (excluding prepaid expenses) 12 3,100 2,840 Other long-term assets 397 368 Total financial assets (1) 442,692 118,759
Schedule of financial liabilities	(in KUSD) Note December 31, 2020 December 31, 2019 Financial liabilities - financial liabilities Trade accounts payable 5,279 3,329 Accrued liabilities and other payables 19 30,375 15,430 Lease liabilities, short-term and long-term 15 3,467 5,031 Convertible loans, short-term and long-term 21 38,406 — Convertible loans, derivatives 21 73,208 — Other long-term liabilities 221 — Total financial liabilities (1) 150,956 23,790 Net financial position 291,736 94,969 (1) Financial assets and Financial liabilities are recorded at historical or amortized cost with the exception of Convertible loans, derivatives which are recorded at fair value.
Schedule of net debt rollforward	The following is the net debt rollforward for the Company for 2020. No net debt rollforward was presented for 2019 as the Company’s only debt obligation related to its lease liabilities, which were deemed not to be material. Notes Cash and cash equivalents Convertible loan (1) Embedded derivative (1) Lease liabilities (2) Total December 31, 2019 115,551 — — (5,031) 110,520 Issuance of convertible loan 21 65,000 (37,203) (27,797) — — Convertible loan transaction costs 21 (3,673) 2,102 — — (1,571) Fair value adjustments 21 — — (23,432) — (23,432) Convertible loan accretion 21 — (4,756) — — (4,756) Interest payments (1,557) 1,452 105 — Lease principal 15 (1,144) — — 1,144 — Other lease activity including foreign exchange 15 — — — 315 315 Net cash outflow 264,783 — — — 264,783 Foreign exchange on cash 235 — — — 235 December 31, 2020 (3) 439,195 (38,406) (51,229) (3,467) 346,093 (1) See note 21, “Convertible loans for further information. (2) See note 15, “Leases” for further information.
Schedule of credit quality	The credit quality of financial assets that are neither past due nor impaired is assessed below by reference to S&P’s credit ratings (where available) or to historical information about counterparty default rates: (in KUSD) December 31, 2020 December 31, 2019 Cash and cash equivalents UBS 144,989 51,983 Credit Suisse 145,238 62,652 JP Morgan Chase 3,768 916 Bank of America 145,200 — 439,195 115,551

Deferred income taxes and tax_2

Deferred income taxes and tax credit (Tables)	12 Months Ended
	Dec. 31, 2020
Income Taxes [Abstract]
Schedule of unrecognized temporary differences, unused tax losses and unused tax credits	Unrecognized temporary differences, unused tax losses and unused tax credits (in KUSD) December 31, 2020 December 31, 2019 Deductible temporary differences, unused tax losses and unused tax credits for which no deferred tax assets have been recognized are attributable to the following: Taxes losses 613,206 437,013 Unused R&D US tax credit 26,255 10,765 Deductible temporary differences related to the retirement benefit plan 3,543 2,684 Deductible temporary differences related to IFRS 16 338 (39) Offset of recognized temporary differences related to intangible assets (2,364) (2,364) Temporary difference related to investment in joint venture (24,368) — Temporary difference related to convertible loan (27,614) — Total 588,996 448,059
Schedule of years of exipry for tax losses and tax credits to be carried forward	Tax losses not recognized and to be carried forward (in KUSD): Years of expiry December 31, 2020 December 31, 2019 2020 — 14,735 2021 19,889 19,889 2022 31,128 31,128 2023 38,441 38,441 2024 92,012 92,012 Beyond 2025 431,736 240,808 613,206 437,013 R&D USA tax credits carried forward (in KUSD): Years of expiry December 31, 2020 December 31, 2019 2036 1,059 783 2037 2,569 1,839 2038 7,117 3,387 2039 7,026 4,756 2040 8,484 — 26,255 10,765

Accrued liabilities and other_2

Accrued liabilities and other payables (Tables)	12 Months Ended
	Dec. 31, 2020
Subclassifications of assets, liabilities and equities [abstract]
Schedule of Accrued liabilities and other payables	(in KUSD) December 31, 2020 December 31, 2019 Payroll and social charges 12,063 5,726 R&D costs 15,333 8,922 Other 2,979 782 30,375 15,430

Pension obligations (Tables)

Pension obligations (Tables)	12 Months Ended
	Dec. 31, 2020
Employee Benefits [Abstract]
Schedule of movement in the net defined benefit obligation	The net amount recognized on the balance sheet comprises: (in KUSD) December 31, 2020 December 31, 2019 Present value of defined benefit obligation for funded plan 11,809 7,880 Fair value of plan assets (8,266) (5,196) Deficit of funded plan: liability on the balance sheet 3,543 2,684 The movement in the net defined benefit obligation over the year is as follows: (in KUSD) Present value Fair value of Total Defined benefit plan - pension costs: January 1, 2019 4,372 (2,986) 1,386 Current service cost 769 — 769 Impact of plan changes (319) — (319) Interest cost / (income) 37 (25) 12 Defined benefit plan - pension costs 487 (25) 462 Employee contributions 257 (257) — Employer contributions — (515) (515) Transfers from joiners' previous plans 1,302 (1,302) — 1,559 (2,074) (515) Exchange differences 74 (69) 5 Remeasurements: Change in financial assumptions 686 — 686 Other actuarial losses 609 — 609 Plan asset gains — (2) (2) Exchange differences 93 (40) 53 Remeasurements 1,388 (42) 1,346 December 31, 2019 7,880 (5,196) 2,684 (in KUSD) Present value Fair value of Total Defined benefit plan - pension costs: January 1, 2020 7,880 (5,196) 2,684 Current service cost 960 — 960 Interest cost / (income) 17 (11) 6 Defined benefit plan - pension costs 977 (11) 966 Employee contributions 348 (348) — Employer contributions — (690) (690) Transfers from joiners' previous plans 1,451 (1,451) — 1,799 (2,489) (690) Exchange differences 838 (560) 278 Remeasurements: Other actuarial losses 775 — 775 Plan asset gains — (10) (10) Change in demographic assumptions (460) — (460) Remeasurements 315 315 (10) 305 December 31, 2020 11,809 (8,266) 3,543
Schedule of actuarial assumptions	The principal actuarial assumptions used for accounting purposes are as follows for all periods presented: 2020 2019 Discount rate 0.20 % 0.20 % Interest credited on savings accounts 0.20 % 0.20 % Future salary increases 1.50 % 1.50 % Future pension increases 0.00 % 0.00 %
Schedule of actuarial assumptions	The average life expectancy in years after retirement of a pensioner retiring at age 65 (male) and 64 (female) on the balance sheet date is as follows: 2020 2019 Male 22.45 22.61 Female 25.26 25.64
Schedule of sensitivity of defined benefit obligation	The sensitivity of the defined benefit obligation and of the service cost to changes in the weighted principal assumption is: 2020 Increase in Impact on defined Decrease in Impact on defined Discount rate 0.25 % (5.00) % (0.25) % 5.40 % Future salary increases 0.50 % 0.70 % (0.50) % (0.70) % Interest credited on savings accounts 0.50 % 2.80 % (0.50) % (2.70) % Future pension increases 0.50 % 6.70 % (0.50) % (6.00) % 2019 Increase in Impact on defined Decrease in Impact on defined Discount rate 0.25 % (5.40) % (0.25) % 5.90 % Future salary increases 0.50 % 0.90 % (0.50) % (0.90) % Interest credited on savings accounts 0.50 % 3.20 % (0.50) % (3.00) % Future pension increases 0.50 % 7.00 % (0.50) % (6.30) %
Schedule of plan assets	Investments by asset class are as follows: (in KUSD) December 31, 2020 December 31, 2019 Cash 126 155 Bonds 4,658 3,065 Shares 564 329 Real estates and mortgages 2,353 1,303 Alternative investments 565 344 8,266 5,196
Schedule of defined benefit plan reserves	The movement in the defined benefit plan reserves (included in “Other reserves”) is as follows: (in KUSD) 2020 2019 January 1 (2,389) (1,043) Remeasurements of defined benefit pension plan (305) (1,346) December 31 (2,694) (2,389)

Convertible loans (Tables)

Convertible loans (Tables)	12 Months Ended
	Dec. 31, 2020
Financial Instruments [Abstract]
Schedule of key inputs used for valuation	Key inputs for the valuations as of December 31, 2020 and April 24, 2020 were as follows: As of December 31, 2020 April 24, 2020 Exercise price, in USD 24.70 22.10 Forced conversion price, in USD 67.93 60.78 Share price in USD 32.01 17.00 Risk-free interest rate 0.3 % 0.4 % Expected volatility 90 % 82 % Expected term 52 months 61 months Dividend yield — — Recovery rate 5 % 5 % Implied bond yield 13.3 % 21.0 % As of December 31, 2020 Exercise price, in USD 28.50 Forced conversion price, in USD 78.38 Share price in USD 32.01 Risk-free interest rate 0.3 % Expected volatility 90 % Expected term 5 months Dividend yield — Recovery rate 5 % Implied bond yield 7.4 %
Schedule of borrowings	On the basis of the valuation of the conversion option derivative as of April 24, 2020, the USD 65.0 million amount of the first tranche of convertible loans was accounted for on inception as follows: in KUSD Embedded derivative Residual Total Gross proceeds 27,797 37,203 65,000 Less: transaction costs (1,571) (2,102) (3,673) Net 26,226 35,101 61,327

Share-based compensation expe_2

Share-based compensation expense (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangements [Abstract]
Schedule of Shares Outstanding	Movements in the number of awards outstanding and their related weighted average strike prices are as follows: 2020 2019 Average strike price in USD per share Number of awards Average strike price in USD per share Number of awards At the beginning of the year 18.75 1,020,434 — — Granted 28.62 3,347,766 18.75 1,020,434 Forfeited 19.83 (88,332) — — Exercised 18.75 (2,895) — — At the end of the year 26.45 4,276,973 18.75 1,020,434 Weighted average remaining contractual life of awards outstanding at end of period 9.29 9.96 Grant date Expiry date Strike price Awards December 31, 2020 December 9, 2019 2029 18.75 985,848 April 1, 2020 2030 18.75 213,764 April 29, 2020 2030 18.75 1,272,213 May 15, 2020 2030 19.00 366,257 June 4, 2020 2030 34.99 341,403 July 1, 2020 2030 48.77 84,589 July 20, 2020 2030 48.59 490,883 August 3, 2020 2030 46.83 61,576 August 17, 2020 2030 38.62 135,064 September 1, 2020 2030 41.19 125,850 October 1, 2020 2030 32.15 101,875 November 2, 2020 2030 29.01 40,220 December 1, 2020 2030 38.02 57,431 Total 4,276,973
Schedule of Fair Value Assumption For Options Granted	The fair values of the options granted during the years ended December 31, 2020 and 2019 were determined on the date of grant using the following assumptions: Year ended December 31, 2020 Year ended December 31, 2019 a) weighted average share price in USD 15.95-48.77 16.31 b) strike price in USD 18.75-48.77 18.75 c) expected volatility in % 80-206 176.6 d) award life in # of years 5.02-6.08 5.65 e) expected dividends in % 0 0 f) risk-free interest rate in % 0.29-0.70 1.67
Schedule of Other Equity Instruments Outstanding	Number of awards Weighted average grant date fair value December 31, 2019 — — Granted 149,984 46.50 December 31, 2020 149,984 46.50
Schedule of Share-based Compensation Reserve	The movement in the Share-based Compensation Reserves (included in Other reserves within equity) is as follows: (in KUSD) 2020 2019 2018 January 1 7,862 6,745 6,276 Incentive Plan 2014 361 437 108 Share Purchase Plan 2016 7,417 332 361 2019 Equity Incentive Plan - Options 33,355 348 — 2019 Equity Incentive Plan - RSUs 1,795 — — Tax and social charge deductions - Incentive Plan 2014 (5,343) — — December 31 45,447 7,862 6,745

Share capital (Tables)

Share capital (Tables)	12 Months Ended
	Dec. 31, 2020
Share Capital, Reserves And Other Equity Interest [Abstract]
Schedule of movements in share capital	The movements in the Company’s share capital, share premium and treasury shares accounts for the years ended December 31, 2020, 2019 and 2018 are set out in the following table: Issued share capital Share premium Treasury shares Increase / (Decrease) in net assets Price per share Issued share capital Treasury shares Outstanding share capital In KUSD Number of shares issued Number of shares (held or received) / delivered Number of shares outstanding December 18, 2018 Issuance of share capital 4 — — 4 CHF 0.08 450,000 — 450,000 December 18, 2018 Transaction costs, issuance of share capital (28) — (28) — — — Movements during the year ended December 31, 2018 4 (28) — (24) 450,000 — 450,000 Balances as of January 1, 2018, revised for share consolidation and share split 397 452,296 — 452,693 47,375,000 — 47,375,000 Balance at December 31, 2018 401 452,268 — 452,669 47,825,000 — 47,825,000 February 6, 2019 Increase share capital 1 — — 1 CHF 0.008 75,000 — 75,000 February 6, 2019 Transaction costs, increase in share capital — (19) — (19) — — — June 7, 2019 Increase in share capital 22 75,578 — 75,600 CHF 0.008 2,700,000 — 2,700,000 June 7, 2019 Transaction costs, increase in share capital — (1,432) — (1,432) — — — June 14, 2019 Increase in share capital — 700 — 700 CHF 0.008 25,000 — 25,000 June 14, 2019 Transaction costs, increase in share capital — (13) — (13) — — — July 5, 2019 Increase in share capital 7 26,943 — 26,950 CHF 0.008 962,500 — 962,500 July 5, 2019 Transaction costs, increase in share capital — (306) — (306) — — — August 22, 2019 Transfer from share premium for par value increase 3,789 (3,789) — — — — — September 2, 2019 Purchase of treasury shares 141 — (141) — CHF 0.08 1,750,000 (1,750,000) — September 2, 2019 Transaction costs, increase in share capital — (8) — (8) — — — December 16, 2019 Sale of treasury shares — — 41 41 CHF 0.08 — 509,460 509,460 Movements during the year ended December 31, 2019 3,960 97,654 (100) 101,514 5,512,500 (1,240,540) 4,271,960 Balances as of January 1, 2019, revised for share consolidation and share split 401 452,268 — 452,669 47,825,000 — 47,825,000 Balance at December 31, 2019 4,361 549,922 (100) 554,183 53,337,500 (1,240,540) 52,096,960 April 15, 2020 Shares surrendered by Share Purchase Plan 2013 and Share Purchase Plan 2016 participants to settle share purchase plan promissory notes — 11,208 (11,208) — USD 18.75 — (597,774) (597,774) April 16, 2020 Issuance of shares per shareholder's agreement addendum through capitalization of reserves 393 (393) — — CHF 0.08 4,777,996 — 4,777,996 April 24, 2020 Elimination of fractional holdings — — — — CHF 0.08 — 51 51 May 19, 2020 Issuance of shares to be held as treasury 34 — (34) — CHF 0.08 408,873 (408,873) — May 19, 2020 Grant of shares to settle Incentive Plan 2014 awards, net — (29) 29 — CHF 0.08 — 356,144 356,144 May 19, 2020 Issuance of shares at IPO 1,007 231,661 — 232,668 USD 19.00 12,245,631 — 12,245,631 May 19, 2020 Sale of shares under greenshoe option — 23,591 11,309 34,900 USD 19.00 — 1,836,844 1,836,844 May 19, 2020 Transaction costs, IPO and greenshoe option — (23,355) — (23,355) — — — September 28, 2020 Issuance of shares at follow-on offering 519 203,481 — 204,000 USD 34.00 6,000,000 — 6,000,000 September 28, 2020 Transaction costs, follow-on offering — (15,084) — (15,084) — — — September 30, 2020 Other — — — — CHF 0.08 — 2,796 2,796 December 14, 2020 Shares issued for exercise of option awards — 34 — 34 CHF 0.08 — 1,861 1,861 December 16, 2020 Shares issued for exercise of option awards — 10 — 10 CHF 0.08 — 517 517 December 29, 2020 Shares issued for exercise of option awards — 10 — 10 CHF 0.08 — 517 517 Movements during the year ended December 31,2020 1,953 431,134 96 433,183 23,432,500 1,192,083 24,624,583 Balances reported at December 31, 2019, revised for share consolidation and share split 4,361 549,922 (100) 53,337,500 (1,240,540) 52,096,960 Balance at December 31, 2020 6,314 981,056 (4) 76,770,000 (48,457) 76,721,543

Commitments (Tables)

Commitments (Tables)	12 Months Ended
	Dec. 31, 2020
Other Provisions, Contingent Liabilities And Contingent Assets [Abstract]
Schedule of Commitments	These milestone payments relate to product candidates in the following phases: (in KUSD): R&D Phase Development Regulatory Sales-based Total Pre-clinical 53,497 11,650 158,259 223,406 Phase I 23,719 19,000 73,500 116,219 Phase II 10,797 — — 10,797 December 31, 2020 88,013 30,650 231,759 350,422 R&D Phase Development Regulatory Sales-based Total Pre-clinical 55,290 19,000 118,000 192,290 Phase I 23,615 19,000 73,500 116,115 Phase II 15,568 — — 15,568 December 31, 2019 94,473 38,000 191,500 323,973

Related parties (Tables)

Related parties (Tables)	12 Months Ended
	Dec. 31, 2020
Related Party [Abstract]
Key Management Compensation	Key management compensation was: (in KUSD) Year ended December 31, 2020 Year ended December 31, 2019 Year ended December 31, 2018 Salaries and other short-term employee benefits 7,690 5,364 4,512 Pension costs 455 407 299 Share-based compensation expenses 16,752 396 341 Other compensation 196 73 183 25,093 6,240 5,335

Loss per share (Tables)

Loss per share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings per share [abstract]
Schedule of loss per share and potentially dilutive securities	The basic loss per share is calculated by dividing the net loss attributable to shareholders by the weighted average number of shares in issue during the period, excluding common shares owned by the Company and held as treasury shares, as follows: For the Years Ended December 31, (in KUSD, except per share amounts) 2020 2019 2018 Net loss attributable to shareholders (246,290) (116,484) (123,096) Weighted average number of shares in issue (1) 65,410,292 49,279,961 46,600,000 Basic and diluted loss per share (in USD) (3.77) (2.36) (2.64) (1) Share data have been revised to give effect to the share split and share consolidation as explained in note 2 (iv) and note 2 (v), respectively as all Class B, C, D and E preferred shares were converted into common shares upon the completion of the IPO, loss per share data are presented on that basis for all periods. Potentially dilutive securities that were not included in the diluted per share calculations because the effect of including them would be anti-dilutive were as follows: For the Years Ended December 31, 2020 2019 2018 Incentive Plan 2014 — 2,074,996 1,959,782 Share Purchase Plan 2016 — 2,784,918 2,369,521 2019 Equity Incentive Plan - Share Options 2,904,673 61,506 — 2019 Equity Incentive Plan - RSUs 63,281 — — Conversion of the principal amount of convertible loans into the Company's common shares 1,665,465 — — 4,633,419 4,921,420 4,329,303

Foreign currency exchange rate

Foreign currency exchange rate (Tables)	12 Months Ended
	Dec. 31, 2020
Effects Of Changes In Foreign Exchange Rates [Abstract]
Schedule of Foreign currency exchange rate	The following exchange rates have been used for the translation of the financial statements of ADCT UK, the functional currency of which is the British pound: USD / GBP Year ended December 31, 2020 Year ended December 31, 2019 Year ended December 31, 2018 Closing rate, GBP 1 1.36501 1.3186 1.2690 Weighted average exchange rate, GBP 1 1.28423 1.2747 1.3501

Corporate Information - Narrati

Corporate Information - Narrative (Details)	12 Months Ended
	Dec. 31, 2020subsidiaryantibody_drug_conjugatenon-antibody_drug_conjugate	Dec. 31, 2011antibodyDrugConjugateTargetnon-antibodyDrugConjugateTarget
Corporate Information And Statement Of IFRS Compliance [Abstract]
Number of subsidiaries	2
Number of ADC's that can be developed	11	11
Number of non-ADC's that can be developed	10	10

Basis of preparation - Going Co

Basis of preparation - Going Concern Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Corporate Information And Statement Of IFRS Compliance [Abstract]
Cash and cash equivalents, minimum quarterly balance	$ 50,000
Cash and cash equivalents	$ 439,195	$ 115,551	$ 138,807	$ 262,752

Basis of preparation - Share Sp

Basis of preparation - Share Split (Details)	Sep. 19, 2019
Corporate Information And Statement Of IFRS Compliance [Abstract]
Share split ratio	0.000064

Basis of preparation - Share Co

Basis of preparation - Share Consolidation (Details)	Apr. 24, 2020
Corporate Information And Statement Of IFRS Compliance [Abstract]
Share consolidation ratio	0.8

Basis of preparation - Initial

Basis of preparation - Initial Public Offering and Follow-On Public Offering (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 28, 2020	May 19, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of classes of share capital [line items]
Proceeds from public offering of common shares, net of transaction costs			$ 433,158	$ 0	$ 0
Issuance of shares at follow-on offering			204,000
Share premium
Disclosure of classes of share capital [line items]
Issuance of shares at follow-on offering	$ 203,481		$ 203,481
Increase in share premium		$ 255,300
Initial Public Offering
Disclosure of classes of share capital [line items]
Number of shares issued (in shares)		14,082,475
Offering price per share (in USD per share)		$ 19
Proceeds from issue of ordinary shares, net		$ 267,600
Proceeds from public offering of common shares, net of transaction costs		244,200
Transaction costs		4,700
Underwriting discounts and commissions		$ 18,700
Underwriters Option Member
Disclosure of classes of share capital [line items]
Number of shares issued (in shares)		1,836,844
Follow-on Public Offering
Disclosure of classes of share capital [line items]
Number of shares issued (in shares)	6,000,000
Offering price per share (in USD per share)	$ 34
Proceeds from issue of ordinary shares, net	$ 204,000
Proceeds from public offering of common shares, net of transaction costs	188,900
Issuance of shares at follow-on offering	203,500
Transaction costs	2,900
Underwriting discounts and commissions	$ 12,200

Basis of preparation - Overland

Basis of preparation - Overland Joint Venture (Details) $ in Thousands	Dec. 14, 2020USD ($)product_candidate	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Disclosure of joint ventures [line items]
Deferred gain of joint venture		$ 23,539	$ 0
Overland ADCT BioPharma
Disclosure of joint ventures [line items]
Proportion of equity interest in joint venture	49.00%
Fair value of investments in joint ventures	$ 48,040
Gain on joint venture	$ 24,501
Deferred gain of joint venture		23,539
Proportionate share in joint venture's net loss		$ 132
Overland Pharmaceuticals | Overland ADCT BioPharma
Disclosure of joint ventures [line items]
Number of product candidates to be developed and commercialized | product_candidate	4
Investment in joint venture	$ 50,000
Proportion of equity interest in joint venture	51.00%

Basis of preparation - Schedule

Basis of preparation - Schedule of movement in interest in joint venture (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Disclosure of joint ventures [line items]
Beginning balance	$ 0
Ending balance	47,908
Overland ADCT BioPharma
Disclosure of joint ventures [line items]
Beginning balance	0
Initial investment	48,040
Share of results with joint venture	$ (132)

Basis of preparation - Summary

Basis of preparation - Summary of financial information in joint venture (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of joint ventures [line items]
Cash and cash equivalents	$ 439,195	$ 439,195	$ 115,551	$ 138,807	$ 262,752
Intangible assets	10,179	10,179	8,434
Total liabilities	178,187	178,187	26,526
Total operating expense		219,263	121,739	127,081
Net loss		(246,290)	$ (116,484)	$ (123,096)
Overland ADCT BioPharma
Disclosure of joint ventures [line items]
Cash and cash equivalents	50,000	50,000
Intangible assets	48,040	48,040
Total liabilities	269	269
Net assets	97,771	$ 97,771
Total operating expense	269
Net loss	$ 269

Significant Accounting Polici_4

Significant Accounting Policies (Details) $ in Millions	Apr. 24, 2020USD ($)borrowingComponent	Dec. 31, 2020regionsegmentbusiness	May 19, 2020USD ($)
Disclosure of detailed information about borrowings [line items]
Number of businesses, managed and operated | business		1
Number of operating segment | segment		1
Number of regions company is located in | region		3
Facility Agreement with Deerfield Partners, L.P.
Disclosure of detailed information about borrowings [line items]
Borrowings, maximum borrowing capacity	$ 115
Number of borrowing components | borrowingComponent	2
Disbursement upon completion of IPO
Disclosure of detailed information about borrowings [line items]
Borrowings, maximum borrowing capacity	$ 65
Borrowings	65		$ 65
Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about borrowings [line items]
Borrowings, maximum borrowing capacity	50
Borrowings	$ 50

Significant Accounting Polici_5

Significant Accounting Policies - Useful Lives (Details)	12 Months Ended
	Dec. 31, 2020
Laboratory equipment
Disclosure of detailed information about property, plant and equipment [line items]
Useful life measured as period of time, property, plant and equipment	5 years
Office equipment
Disclosure of detailed information about property, plant and equipment [line items]
Useful life measured as period of time, property, plant and equipment	5 years
Hardware
Disclosure of detailed information about property, plant and equipment [line items]
Useful life measured as period of time, property, plant and equipment	3 years
Minimum | Leasehold improvements
Disclosure of detailed information about property, plant and equipment [line items]
Useful life measured as period of time, property, plant and equipment	3 years
Maximum | Leasehold improvements
Disclosure of detailed information about property, plant and equipment [line items]
Useful life measured as period of time, property, plant and equipment	10 years

New and amended IFRS standard_2

New and amended IFRS standards - Schedule of Lease Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Accounting Policies, Changes In Accounting Estimates And Errors [Abstract]
Operating lease commitments at December 31, 2018				$ 4,378
Discounted at the incremental borrowing rate as at January 1, 2019			$ 3,976
Short-term leases recognized on a straight-line basis as expenses			(15)
Low-value leases recognized on a straight-line basis as expenses			0
Extension options reasonably certain to be exercised			1,462
Total lease liabilities	$ 3,467	$ 5,031	5,423	$ 5,423
Lease liabilities, short-term	1,002	1,132	924
Lease liabilities, long-term	$ 2,465	$ 3,899	$ 4,499

New and amended IFRS standard_3

New and amended IFRS standards - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019
Disclosure of initial application of standards or interpretations [line items]
Weighted average lessee's incremental borrowing rate applied to lease liabilities recognised at date of initial application of IFRS 16				2.66%
Right-of-use assets	$ 3,129	$ 4,898
Lease liabilities, contractual rent	3,467	5,031	$ 5,423	$ 5,423
Depreciation, right-of-use assets	1,151	1,064
Interest	105	141	0
Payments of lease liabilities, classified as financing activities	$ 1,144	1,002	$ 0
IFRS 16
Disclosure of initial application of standards or interpretations [line items]
Right-of-use assets				5,423
Lease liabilities, contractual rent				$ 5,423
Depreciation, right-of-use assets		1,064
Operating lease expense		1,002
Interest		141
Payments of lease liabilities, classified as financing activities		1,143
Payments of lease liabilities, classified as operating activities		$ 1,143

Financial risk management - Cas

Financial risk management - Cash and Cash Equivalents (Details) - Currency risk € in Thousands, £ in Thousands, SFr in Thousands, $ in Thousands	Dec. 31, 2020USD ($)	Dec. 31, 2020CHF (SFr)	Dec. 31, 2020GBP (£)	Dec. 31, 2020EUR (€)	Dec. 31, 2019USD ($)	Dec. 31, 2019CHF (SFr)	Dec. 31, 2019GBP (£)	Dec. 31, 2019EUR (€)
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	$ 439,195				$ 115,551
In USD
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	435,750				109,939
In CHF
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	426	SFr 376			472	SFr 457
In GBP
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	2,861		£ 2,096		4,654		£ 3,529
In EUR
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	$ 158			€ 129	$ 486			€ 433

Financial risk management - Nar

Financial risk management - Narrative (Details) $ in Thousands	Apr. 24, 2020USD ($)borrowingComponent	Dec. 31, 2020USD ($)	May 19, 2020USD ($)	Dec. 31, 2019USD ($)
Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about financial instruments [line items]
Borrowings	$ 50,000
Disbursement upon completion of IPO
Disclosure of detailed information about financial instruments [line items]
Borrowings	$ 65,000		$ 65,000
Facility Agreement with Deerfield Partners, L.P.
Disclosure of detailed information about financial instruments [line items]
Number of borrowing components | borrowingComponent	2
Interest rate risk | Risk-free interest rate
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis for types of interest rate risk, reasonably possible change in risk variable		10.00%
Interest rate risk | Implied bond yield
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis for types of interest rate risk, reasonably possible change in risk variable		10.00%
Interest rate risk | Disbursement upon receipt of regulatory approval for Lonca | Risk-free interest rate
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis for types of interest rate risk, reasonably possible change in risk variable, increase on derivative values		$ 4
Sensitivity analysis for types of interest rate risk, reasonably possible change in risk variable, decrease on derivative values		4
Interest rate risk | Disbursement upon receipt of regulatory approval for Lonca | Implied bond yield
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis for types of interest rate risk, reasonably possible change in risk variable, increase on derivative values		875
Sensitivity analysis for types of interest rate risk, reasonably possible change in risk variable, decrease on derivative values		846
Interest rate risk | Disbursement upon completion of IPO | Risk-free interest rate
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis for types of interest rate risk, reasonably possible change in risk variable, increase on derivative values		5
Sensitivity analysis for types of interest rate risk, reasonably possible change in risk variable, decrease on derivative values		5
Interest rate risk | Disbursement upon completion of IPO | Implied bond yield
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis for types of interest rate risk, reasonably possible change in risk variable, increase on derivative values		2,088
Sensitivity analysis for types of interest rate risk, reasonably possible change in risk variable, decrease on derivative values		$ 898
Volatility Risk
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis for volatility, reasonably possible change in risk variable		10.00%
Volatility Risk | Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis for types of volatility risk, reasonably possible change in risk variable, increase on derivative values		$ 234
Sensitivity analysis for types of volatility risk, reasonably possible change in risk variable, decrease on derivative values		52
Volatility Risk | Disbursement upon completion of IPO
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis for types of volatility risk, reasonably possible change in risk variable, increase on derivative values		2,043
Sensitivity analysis for types of volatility risk, reasonably possible change in risk variable, decrease on derivative values		$ 248
In CHF | Currency risk
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis for types of foreign currency risk, reasonably possible change in risk variable		10.00%
Sensitivity analysis for types of foreign currency risk, reasonably possible change in risk variable, impact on pre-tax loss		$ 1,013
Sensitivity analysis for types of foreign currency risk, reasonably possible change in risk variable, impact on net monetary assets				$ 201
In EUR | Currency risk
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis for types of foreign currency risk, reasonably possible change in risk variable		10.00%
Sensitivity analysis for types of foreign currency risk, reasonably possible change in risk variable, impact on pre-tax loss		$ 214
Sensitivity analysis for types of foreign currency risk, reasonably possible change in risk variable, impact on net monetary assets				95
In GBP | Currency risk
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis for types of foreign currency risk, reasonably possible change in risk variable		10.00%
Sensitivity analysis for types of foreign currency risk, reasonably possible change in risk variable, impact on pre-tax loss		$ 323
Sensitivity analysis for types of foreign currency risk, reasonably possible change in risk variable, impact on net monetary assets		$ 439		320
Sensitivity analysis for types of foreign currency risk, reasonably possible change in risk variable, impact on net monetary liabilities				$ 290

Financial risk management - Sch

Financial risk management - Schedule of Financial Liabilities By Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Apr. 24, 2020	Dec. 31, 2019
Disclosure of detailed information about financial instruments [line items]
Financial liabilities	$ 150,956		$ 23,790
Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about financial instruments [line items]
Borrowings, maximum borrowing capacity		$ 50,000
Less than 1 year | Liquidity risk
Disclosure of detailed information about financial instruments [line items]
Trade and other payables, undiscounted cash flows	5,279		3,329
Gross lease liabilities	1,050		1,246
Convertible loans, short-term	3,921
Convertible loans, long-term	0
Financial liabilities	10,250		4,575
1-3  years | Liquidity risk
Disclosure of detailed information about financial instruments [line items]
Trade and other payables, undiscounted cash flows	0		0
Gross lease liabilities	1,047		1,859
Convertible loans, short-term	7,842
Convertible loans, long-term	0
Financial liabilities	8,889		1,859
3-5  years | Liquidity risk
Disclosure of detailed information about financial instruments [line items]
Trade and other payables, undiscounted cash flows	0		0
Gross lease liabilities	642		2,265
Convertible loans, short-term	7,703
Convertible loans, long-term	65,000
Financial liabilities	73,345		2,265
More than 5 years | Liquidity risk
Disclosure of detailed information about financial instruments [line items]
Trade and other payables, undiscounted cash flows	0		0
Gross lease liabilities	903		0
Convertible loans, short-term	0
Convertible loans, long-term	0
Financial liabilities	$ 903		$ 0

Critical accounting estimates a

Critical accounting estimates and judgements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of detailed information about intangible assets [line items]
Impairment losses	$ 216,000	$ 0	$ 227,000
Licenses
Disclosure of detailed information about intangible assets [line items]
Additions	1,923,000	1,731,000
Impairment losses	$ 216,000	$ 0	$ 227,000

Contract revenue and contract_2

Contract revenue and contract liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue From Contracts With Customers [Abstract]
Contract revenue	$ 0	$ 2,340	$ 1,140
Deferred revenue	$ 0	$ 0

Other income (expense) - Schedu

Other income (expense) - Schedule of Other Income (Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Analysis of income and expense [abstract]
Other income	$ 584	$ 1,655	$ 0
Convertible loans, derivatives, change in fair value (expense)	(45,411)	0	0
Convertible loans, first tranche, derivative, transaction costs	1,571	0	0
Share of results with joint venture	24,368	0	0
Financial income	832	2,253	2,856
Financial expense	(4,926)	(156)	0
Exchange differences (loss) gain	(576)	(255)	213
Total other (expense) income	$ (26,700)	$ 3,497	$ 3,069

Other income (expense)- Narrati

Other income (expense)- Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Analysis of income and expense [abstract]
Financial income	$ 832	$ 2,253	$ 2,856
Exchange differences (loss) gain	$ (576)	$ (255)	$ 213

Employee expenses - Schedule of

Employee expenses - Schedule of Employee expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Analysis of income and expense [abstract]
Wages, salaries and other costs	$ 44,058	$ 24,061	$ 19,245
Social security costs	7,292	3,871	3,452
Expense recognized	42,928	1,117	469
Defined benefit plan costs	966	462	535
Defined contribution plan costs	727	540	481
Employee expenses	$ 95,971	$ 30,051	$ 24,182

Employee expenses - Narrative (

Employee expenses - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Analysis of income and expense [abstract]
Employee expenses	$ 95,971	$ 30,051	$ 24,182
Adjustments for increase (decrease) in employee benefit liabilities	$ 65,920

Expenses by nature - Schedule o

Expenses by nature - Schedule of Expenses by nature (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Detailed Information About Expenses By Nature [Line Items]
Research and development expenses	$ 142,032,000	$ 107,537,000	$ 118,313,000
Selling and marketing expenses	22,101,000	0	0
General and administrative expenses	55,130,000	14,202,000	8,768,000
Total operating expense	219,263,000	121,739,000	127,081,000
External Costs
Disclosure Of Detailed Information About Expenses By Nature [Line Items]
Research and development expenses	97,768,000	82,621,000	99,067,000
Selling and marketing expenses	11,887,000	0	0
General and administrative expenses	13,637,000	9,067,000	3,832,000
Employee Expenses
Disclosure Of Detailed Information About Expenses By Nature [Line Items]
Research and development expenses	44,264,000	24,916,000	19,246,000
Selling and marketing expenses	10,214,000	0	0
General and administrative expenses	$ 41,493,000	$ 5,135,000	$ 4,936,000

Expenses by nature - Narrative

Expenses by nature - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Analysis of income and expense [abstract]
Research and development expense, milestone payment	$ 5,000,000
Selling and marketing expenses recorded in general and administrative expenses		$ 158,000
Selling and marketing expenses	$ 22,101,000	$ 0	$ 0

Income tax expense - Schedule o

Income tax expense - Schedule of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Abstract]
Current income taxes for the year	$ 417	$ 572	$ 218
Current income taxes related to prior years	(90)	10	6
Income tax expense	$ 327	$ 582	$ 224

Income tax expense - Narrative

Income tax expense - Narrative (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Minimum
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Applicable tax rate	13.68%	11.00%	11.00%
Maximum
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Applicable tax rate	21.00%	27.00%	27.00%
Weighted Average
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Weighted average tax rate	13.80%	11.50%	11.30%

Income tax expense - Schedule_2

Income tax expense - Schedule of Detailed Income Tax Expenses (Credits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Abstract]
Loss before taxes	$ 245,963	$ 115,902	$ 122,872
Tax calculated at tax domestic rates applicable to profits in the respective countries	(33,319)	(12,332)	(13,321)
Income Taxes, Tax Effects [Abstract]
Tax losses for which no deferred income tax asset was recognized	26,112	13,187	13,766
Utilization of R&D tax credit (USA)	(546)	(436)	(310)
Income not subject to tax / (expenses not deductible for tax purposes)	8,166	156	83
Tax relating to prior years	(90)	10	6
Other	4	(3)	0
Income tax expense	$ 327	$ 582	$ 224

Other current assets - Schedule

Other current assets - Schedule of Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Subclassifications of assets, liabilities and equities [abstract]
VAT receivable, net	$ 453	$ 471
Withholding tax receivable	991	626
Prepaid insurance	2,852	0
Prepaid compensation	1,488	0
Prepaid expenses - other	3,815	4,215
UK R&D expenditure credit receivable	1,246	891
Other	410	852
Other current assets	$ 11,255	$ 7,055

Other current assets - Narrativ

Other current assets - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Subclassifications of assets, liabilities and equities [abstract]
Increase in other current assets	$ 4.2

Non-current assets by geograp_3

Non-current assets by geographic area (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Detailed Information About Non-current Assets [Line Items]
Total non-current assets	$ 62,845	$ 14,708
Switzerland
Disclosure Of Detailed Information About Non-current Assets [Line Items]
Total non-current assets	60,231	10,903
United Kingdom
Disclosure Of Detailed Information About Non-current Assets [Line Items]
Total non-current assets	1,132	2,032
United States
Disclosure Of Detailed Information About Non-current Assets [Line Items]
Total non-current assets	$ 1,482	$ 1,773

Property, plant and equipment -

Property, plant and equipment - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	$ 1,376
Ending balance	1,629	$ 1,376
Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	2,960	2,547
Additions	1,021	359
Disposals and scrapping	(675)
Exchange difference	50	54
Ending balance	3,356	2,960
Accumulated amortization
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	(1,584)	(1,007)
Disposals and scrapping	675
Exchange difference	(44)	(25)
Depreciation charge	(774)	(552)
Ending balance	(1,727)	(1,584)
Leasehold improvements
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	324
Ending balance	384	324
Leasehold improvements | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	533	514
Additions	224	17
Disposals and scrapping	(13)
Exchange difference	2	2
Ending balance	746	533
Leasehold improvements | Accumulated amortization
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	(209)	(126)
Disposals and scrapping	13
Exchange difference	(4)	(1)
Depreciation charge	(162)	(82)
Ending balance	(362)	(209)
Laboratory equipment
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	578
Ending balance	408	578
Laboratory equipment | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	1,111	939
Additions	30	131
Disposals and scrapping	(178)
Exchange difference	39	41
Ending balance	1,002	1,111
Laboratory equipment | Accumulated amortization
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	(533)	(310)
Disposals and scrapping	178
Exchange difference	(32)	(19)
Depreciation charge	(207)	(204)
Ending balance	(594)	(533)
Office equipment
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	301
Ending balance	214	301
Office equipment | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	698	597
Additions	84	93
Disposals and scrapping	(117)
Exchange difference	6	8
Ending balance	671	698
Office equipment | Accumulated amortization
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	(397)	(245)
Disposals and scrapping	117
Exchange difference	(4)	(3)
Depreciation charge	(173)	(149)
Ending balance	(457)	(397)
Hardware
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	173
Ending balance	556	173
Hardware | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	618	497
Additions	616	118
Disposals and scrapping	(367)
Exchange difference	3	3
Ending balance	870	618
Hardware | Accumulated amortization
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	(445)	(326)
Disposals and scrapping	367
Exchange difference	(4)	(2)
Depreciation charge	(232)	(117)
Ending balance	(314)	(445)
Construction in progress
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	0
Ending balance	67	0
Construction in progress | Cost
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	0	0
Additions	67	0
Disposals and scrapping	0
Exchange difference	0	0
Ending balance	67	0
Construction in progress | Accumulated amortization
Reconciliation of changes in property, plant and equipment [abstract]
Beginning balance	0	0
Disposals and scrapping	0
Exchange difference	0	0
Depreciation charge	0	0
Ending balance	$ 0	$ 0

Property, plant and equipment_2

Property, plant and equipment - Schedule of Depreciation (Details) - 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]
Depreciation expense	$ 774	$ 552	$ 488
R&D expense
Disclosure of detailed information about property, plant and equipment [line items]
Depreciation expense	589	407	330
G&A expense
Disclosure of detailed information about property, plant and equipment [line items]
Depreciation expense	$ 185	$ 145	$ 158

Leases - Balance Sheet Classifi

Leases - Balance Sheet Classification (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use assets	$ 3,129	$ 4,898
Lease liabilities (short-term)	1,002	1,132	$ 924
Lease liabilities (long-term)	2,465	3,899	4,499
Total lease liabilities	3,467	5,031	$ 5,423	$ 5,423
Properties (offices)
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use assets	3,071	4,820
Vehicles
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use assets	$ 58	$ 78

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2020
Leases [Abstract]
Payments related to noncancellable leases			$ 869
Lease termination, right-of-use asset				$ 583
Lease termination, lease liability				$ 583
Expense relating to short-term leases for which recognition exemption has been used	$ 277	$ 28
Short-term lease payments, due in next fiscal year	$ 130

Leases - Right-of-Use Assets an

Leases - Right-of-Use Assets and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use asset, beginning balance	$ 4,898
Depreciation, right-of-use assets	(1,151)	$ (1,064)
Right-of-use asset, ending balance	3,129	4,898
Cost
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use asset, beginning balance	5,965	5,423
Additions to right-of-use assets		544
Modification of lease terms, right-of-use assets	(583)
Exchange differences, right-of-use-assets	20	22
Disposals to right-of-use assets		(24)
Right-of-use asset, ending balance	5,402	5,965
Accumulated amortization
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use asset, beginning balance	(1,067)	0
Exchange differences, right-of-use-assets	(55)	(16)
Depreciation, right-of-use assets	(1,151)	(1,064)
Disposals to right-of-use assets		13
Right-of-use asset, ending balance	(2,273)	(1,067)
Properties (offices)
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use asset, beginning balance	4,820
Right-of-use asset, ending balance	3,071	4,820
Properties (offices) | Cost
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use asset, beginning balance	5,887	5,399
Additions to right-of-use assets		466
Modification of lease terms, right-of-use assets	(583)
Exchange differences, right-of-use-assets	20	22
Disposals to right-of-use assets		0
Right-of-use asset, ending balance	5,324	5,887
Properties (offices) | Accumulated amortization
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use asset, beginning balance	(1,067)	0
Exchange differences, right-of-use-assets	(55)	(16)
Depreciation, right-of-use assets	(1,131)	(1,051)
Disposals to right-of-use assets		0
Right-of-use asset, ending balance	(2,253)	(1,067)
Vehicles
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use asset, beginning balance	78
Right-of-use asset, ending balance	58	78
Vehicles | Cost
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use asset, beginning balance	78	24
Additions to right-of-use assets		78
Modification of lease terms, right-of-use assets	0
Exchange differences, right-of-use-assets	0	0
Disposals to right-of-use assets		(24)
Right-of-use asset, ending balance	78	78
Vehicles | Accumulated amortization
Disclosure of quantitative information about right-of-use assets [line items]
Right-of-use asset, beginning balance	0	0
Exchange differences, right-of-use-assets	0	0
Depreciation, right-of-use assets	(20)	(13)
Disposals to right-of-use assets		13
Right-of-use asset, ending balance	$ (20)	$ 0

Leases - Right-of-Use Asset Dep

Leases - Right-of-Use Asset Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure of quantitative information about right-of-use assets [line items]
Depreciation, right-of-use assets	$ 1,151	$ 1,064
R&D expense
Disclosure of quantitative information about right-of-use assets [line items]
Depreciation, right-of-use assets	915	837
G&A expense
Disclosure of quantitative information about right-of-use assets [line items]
Depreciation, right-of-use assets	$ 236	$ 227

Leases - Schedule of Lease Liab

Leases - Schedule of Lease Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019
Disclosure Of Quantitative Information About Lease Liabilities [Line Items]
Beginning balance	$ 5,031	$ 5,423
Additions	0	544
Disposals		(12)
Modification of lease terms	(583)
Cash outflow (including interest)	(1,249)	(1,143)
Interest	105	141	$ 0
Exchange difference	163	78
Ending balance	3,467	5,031	5,423
Lease liabilities, short-term	1,002	1,132		$ 924
Lease liabilities, long-term	2,465	3,899		$ 4,499
Properties (offices)
Disclosure Of Quantitative Information About Lease Liabilities [Line Items]
Beginning balance	4,953	5,399
Additions	0	466
Disposals		0
Modification of lease terms	(583)
Cash outflow (including interest)	(1,227)	(1,130)
Interest	102	140
Exchange difference	157	78
Ending balance	3,402	4,953	5,399
Lease liabilities, short-term	981	1,114
Lease liabilities, long-term	2,421	3,839
Vehicles
Disclosure Of Quantitative Information About Lease Liabilities [Line Items]
Beginning balance	78	24
Additions	0	78
Disposals		(12)
Modification of lease terms	0
Cash outflow (including interest)	(22)	(13)
Interest	3	1
Exchange difference	6	0
Ending balance	65	78	$ 24
Lease liabilities, short-term	21	18
Lease liabilities, long-term	$ 44	$ 60

Intangible assets - Schedule of

Intangible assets - Schedule of Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of changes in intangible assets other than goodwill [abstract]
Beginning balance	$ 8,434,000
Impairment charge	(216,000)	$ 0	$ (227,000)
Ending balance	10,179,000	8,434,000
Licenses
Reconciliation of changes in intangible assets other than goodwill [abstract]
Beginning balance	8,368,000
Additions	1,923,000	1,731,000
Impairment charge	(216,000)	0	(227,000)
Ending balance	10,075,000	8,368,000
Software
Reconciliation of changes in intangible assets other than goodwill [abstract]
Beginning balance	66,000
Ending balance	104,000	66,000
Cost
Reconciliation of changes in intangible assets other than goodwill [abstract]
Beginning balance	9,368,000	7,577,000
Additions	2,008,000	1,790,000
Disposals	(65,000)
Exchange difference	1,000	1,000
Ending balance	11,312,000	9,368,000	7,577,000
Cost | Licenses
Reconciliation of changes in intangible assets other than goodwill [abstract]
Beginning balance	9,221,000	7,490,000
Additions	1,923,000	1,731,000
Disposals	0
Exchange difference	0	0
Ending balance	11,144,000	9,221,000	7,490,000
Cost | Software
Reconciliation of changes in intangible assets other than goodwill [abstract]
Beginning balance	147,000	87,000
Additions	85,000	59,000
Disposals	(65,000)
Exchange difference	1,000	1,000
Ending balance	168,000	147,000	87,000
Accumulated amortization
Reconciliation of changes in intangible assets other than goodwill [abstract]
Beginning balance	(934,000)	(903,000)
Disposals	65,000
Exchange difference	(1,000)	(1,000)
Amortization charge	(47,000)	(30,000)
Impairment charge	(216,000)
Ending balance	(1,133,000)	(934,000)	(903,000)
Accumulated amortization | Licenses
Reconciliation of changes in intangible assets other than goodwill [abstract]
Beginning balance	(853,000)	(853,000)
Disposals	0
Exchange difference	0	0
Amortization charge	0	0
Impairment charge	(216,000)
Ending balance	(1,069,000)	(853,000)	(853,000)
Accumulated amortization | Software
Reconciliation of changes in intangible assets other than goodwill [abstract]
Beginning balance	(81,000)	(50,000)
Disposals	65,000
Exchange difference	(1,000)	(1,000)
Amortization charge	(47,000)	(30,000)
Impairment charge	0
Ending balance	$ (64,000)	$ (81,000)	$ (50,000)

Intangible assets - Schedule _2

Intangible assets - Schedule of Intangible Assets Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of detailed information about intangible assets [line items]
Amortisation expense	$ 263	$ 30	$ 252
R&D expense
Disclosure of detailed information about intangible assets [line items]
Amortisation expense	230	14	244
G&A expense
Disclosure of detailed information about intangible assets [line items]
Amortisation expense	$ 33	$ 16	$ 8

Intangible assets - Narrative (

Intangible assets - Narrative (Details)	12 Months Ended
	Dec. 31, 2020USD ($)antibody_drug_conjugateantibodynon-antibody_drug_conjugate	Dec. 31, 2019USD ($)non-antibodyDrugConjugateTargetantibodyDrugConjugateTargetantibody	Dec. 31, 2018USD ($)	Dec. 31, 2011USD ($)antibodyDrugConjugateTargetproductnon-antibodyDrugConjugateTarget
Disclosure of detailed information about intangible assets [line items]
Purchase of intangible assets, classified as investing activities	$ 2,008,000	$ 1,790,000	$ 1,526,000
ADC Targets	11			11
XDC Targets	10			10
Number of approved ADC Targets | antibodyDrugConjugateTarget		11
Number of approved non-ADC Targets | non-antibodyDrugConjugateTarget		10
Number of products available to grant sublicenses | product				1
Period to sublicense products				48 months
Payment of upfront licensing fee				$ 2,500,000
Number of antibodies licensed to produce | antibody	5	5
Impairment losses	$ 216,000	$ 0	227,000
Licenses
Disclosure of detailed information about intangible assets [line items]
Purchase of intangible assets, classified as investing activities				$ 2,500,000
Additions	1,923,000	1,731,000
Impairment losses	216,000	0	$ 227,000
License To Use Technology, Development, Manufacturing And Commercialization
Disclosure of detailed information about intangible assets [line items]
Additions	1,000,000
License To Use Antibody Binders
Disclosure of detailed information about intangible assets [line items]
Additions	548,000
License To Acquire An Antibody
Disclosure of detailed information about intangible assets [line items]
Additions	250,000
License To Use Technology To Generate Antibody Drug Conjugates
Disclosure of detailed information about intangible assets [line items]
Additions	$ 125,000	500,000
License To Acquire Antibody To Be Used In Pre-clinical Formalization, Clinical Testing, Manufacturing And Commercialization
Disclosure of detailed information about intangible assets [line items]
Additions		1,000,000
License To Use Technology For The Production Of Antibodies
Disclosure of detailed information about intangible assets [line items]
Additions		$ 231,000

Financial instruments - Schedul

Financial instruments - Schedule of financial assets and financial liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Disclosure of detailed information about financial instruments [line items]
Financial assets	$ 442,692	$ 118,759
Financial liabilities	150,956	23,790
Net financial position	291,736	94,969
Trade accounts payable
Disclosure of detailed information about financial instruments [line items]
Financial liabilities	5,279	3,329
Accrued liabilities and other payables
Disclosure of detailed information about financial instruments [line items]
Financial liabilities	30,375	15,430
Lease liabilities
Disclosure of detailed information about financial instruments [line items]
Financial liabilities	3,467	5,031
Convertible loans, short-term and long-term
Disclosure of detailed information about financial instruments [line items]
Financial liabilities	38,406	0
Convertible loans, derivatives
Disclosure of detailed information about financial instruments [line items]
Financial liabilities	73,208	0
Other long-term liabilities
Disclosure of detailed information about financial instruments [line items]
Financial liabilities	221	0
Cash and cash equivalents
Disclosure of detailed information about financial instruments [line items]
Financial assets	439,195	115,551
Other current assets (excluding prepaid expenses)
Disclosure of detailed information about financial instruments [line items]
Financial assets	3,100	2,840
Other long-term assets
Disclosure of detailed information about financial instruments [line items]
Financial assets	$ 397	$ 368

Financial instruments - Sched_2

Financial instruments - Schedule of net debt rollforward (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Disclosure of detailed information about financial instruments [line items]
Net debt obligation, beginning balance	$ 110,520
Convertible loan transaction costs	(1,571)
Fair value adjustments	(23,432)
Convertible loan accretion	(4,756)
Other lease activity including foreign exchange	315
Net cash outflow	264,783
Foreign exchange on cash	235
Net debt obligation, ending balance	346,093
Cash and cash equivalents
Disclosure of detailed information about financial instruments [line items]
Net debt obligation, beginning balance	115,551
Issuance of convertible loan	65,000
Convertible loan transaction costs	(3,673)
Interest payments	(1,557)
Lease principal	(1,144)
Net cash outflow	264,783
Foreign exchange on cash	235
Net debt obligation, ending balance	439,195
Convertible loans, short-term and long-term
Disclosure of detailed information about financial instruments [line items]
Net debt obligation, beginning balance	0
Issuance of convertible loan	(37,203)
Convertible loan transaction costs	2,102
Convertible loan accretion	(4,756)
Interest payments	1,452
Net debt obligation, ending balance	(38,406)
Embedded derivative
Disclosure of detailed information about financial instruments [line items]
Net debt obligation, beginning balance	0
Issuance of convertible loan	(27,797)
Fair value adjustments	(23,432)
Net debt obligation, ending balance	(51,229)
Lease liabilities
Disclosure of detailed information about financial instruments [line items]
Net debt obligation, beginning balance	(5,031)
Interest payments	105
Lease principal	1,144
Other lease activity including foreign exchange	315
Net debt obligation, ending balance	$ (3,467)

Financial instruments - Sched_3

Financial instruments - Schedule of credit quality (Details) - Cash and cash equivalents - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Disclosure of credit risk exposure [line items]
Credit exposure	$ 439,195	$ 115,551
UBS
Disclosure of credit risk exposure [line items]
Credit exposure	144,989	51,983
Credit Suisse
Disclosure of credit risk exposure [line items]
Credit exposure	145,238	62,652
JP Morgan Chase
Disclosure of credit risk exposure [line items]
Credit exposure	3,768	916
Bank of America
Disclosure of credit risk exposure [line items]
Credit exposure	$ 145,200	$ 0

Deferred income taxes and tax_3

Deferred income taxes and tax credit - Schedule of unrecognized temporary differences, unused tax losses and unused tax credits (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deductible temporary differences, unused tax losses and unused tax credits for which no deferred tax assets have been recognized	$ 588,996	$ 448,059
Taxes losses
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deductible temporary differences, unused tax losses and unused tax credits for which no deferred tax assets have been recognized	613,206	437,013
Unused R&D US tax credit
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deductible temporary differences, unused tax losses and unused tax credits for which no deferred tax assets have been recognized	26,255	10,765
Deductible temporary differences related to the retirement benefit plan
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deductible temporary differences, unused tax losses and unused tax credits for which no deferred tax assets have been recognized	3,543	2,684
Deductible temporary differences related to IFRS 16
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deductible temporary differences, unused tax losses and unused tax credits for which no deferred tax assets have been recognized	338	(39)
Offset of recognized temporary differences related to intangible assets
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deductible temporary differences, unused tax losses and unused tax credits for which no deferred tax assets have been recognized	(2,364)	(2,364)
Temporary difference related to investment in joint venture
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deductible temporary differences, unused tax losses and unused tax credits for which no deferred tax assets have been recognized	(24,368)	0
Temporary difference related to convertible loan
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deductible temporary differences, unused tax losses and unused tax credits for which no deferred tax assets have been recognized	$ (27,614)	$ 0

Deferred income taxes and tax_4

Deferred income taxes and tax credit - Schedule of years of expiry for tax losses and tax credits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deferred income tax assets recognized	$ 0	$ 0
Tax losses not recognized and to be carried forward	613,206	437,013
R&D USA tax credits carried forward	26,255	10,765
Unused tax losses expired	14,735	6,209
Utilization of R&D tax credit (USA)	$ 546	436	$ 310
R&D tax credit carry forward period	20 years
2020
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax losses not recognized and to be carried forward	$ 0	14,735
2021
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax losses not recognized and to be carried forward	19,889	19,889
2022
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax losses not recognized and to be carried forward	31,128	31,128
2023
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax losses not recognized and to be carried forward	38,441	38,441
2024
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax losses not recognized and to be carried forward	92,012	92,012
Beyond 2025
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax losses not recognized and to be carried forward	431,736	240,808
2036
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
R&D USA tax credits carried forward	1,059	783
2037
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
R&D USA tax credits carried forward	2,569	1,839
2038
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
R&D USA tax credits carried forward	7,117	3,387
2039
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
R&D USA tax credits carried forward	7,026	4,756
2040
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
R&D USA tax credits carried forward	$ 8,484	$ 0

Accrued liabilities and other_3

Accrued liabilities and other payables - Schedule of Accrued liabilities and other payables (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Subclassifications of assets, liabilities and equities [abstract]
Payroll and social charges	$ 12,063	$ 5,726
R&D costs	15,333	8,922
Other	2,979	782
Total current accrued expenses and other current liabilities	$ 30,375	$ 15,430

Accrued liabilities and other_4

Accrued liabilities and other payables - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Subclassifications of assets, liabilities and equities [abstract]
Research and development expense, milestone payment	$ 5

Pension obligations - Narrative

Pension obligations - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)employeeage	Dec. 31, 2019employee
Disclosure of defined benefit plans [line items]
Capital and interest guarantee	100.00%
Guaranteed interest return on employees savings, employees' savings	1.00%
Guaranteed interest return on employees savings, supplementary retirement savings	0.125%
Rate to convert mandatory savings to annuity	6.80%
Retirement age, males	65
Retirement age, females	64
Number of employees covered | employee	28	22
Employer contributions, expected for next year | $	$ 774
Weighted average duration of defined benefit obligation	20 years 10 months 24 days	22 years 8 months 12 days
Minimum
Disclosure of defined benefit plans [line items]
Rate to convert supplementary savings to annuity for males	5.098%
Rate to convert supplementary savings to annuity for females	5.0995%
Maximum
Disclosure of defined benefit plans [line items]
Rate to convert supplementary savings to annuity for males	4.712%
Rate to convert supplementary savings to annuity for females	4.7626%

Pension obligations - Funded st

Pension obligations - Funded status (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of defined benefit plans [line items]
Funded status	$ (3,543)	$ (2,684)	$ (1,386)
Present value of obligation
Disclosure of defined benefit plans [line items]
Funded status	(11,809)	(7,880)	(4,372)
Fair value of plan assets
Disclosure of defined benefit plans [line items]
Funded status	$ (8,266)	$ (5,196)	$ (2,986)

Pension obligations - Schedule

Pension obligations - Schedule of movement in the net defined benefit obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of net defined benefit liability (asset) [line items]
Defined benefit plan, beginning balance	$ 2,684	$ 1,386
Current service cost	960	769
Impact of plan changes		(319)
Interest cost / (income)	6	12
Defined benefit plan costs	(966)	(462)	$ (535)
Employee contributions	0	0
Employer contributions	(690)	(515)
Transfers from joiners' previous plans	0	0
Increase (decrease) through changes other than recognized in profit (loss) or remeasurement, net defined benefit liability (asset)	690	515
Exchange differences	278	5
Change in financial assumptions		686
Other actuarial losses	775	609
Plan asset gains	(10)	(2)
Exchange differences		53
Change in demographic assumptions	(460)
Remeasurements	305	1,346
Defined benefit plan, ending balance	3,543	2,684	1,386
Present value of obligation
Disclosure of net defined benefit liability (asset) [line items]
Defined benefit plan, beginning balance	7,880	4,372
Current service cost	960	769
Impact of plan changes		(319)
Interest cost / (income)	17	37
Defined benefit plan costs	(977)	(487)
Employee contributions	348	257
Employer contributions	0	0
Transfers from joiners' previous plans	1,451	1,302
Increase (decrease) through changes other than recognized in profit (loss) or remeasurement, net defined benefit liability (asset)	(1,799)	(1,559)
Exchange differences	838	74
Change in financial assumptions		686
Other actuarial losses	775	609
Plan asset gains	0	0
Exchange differences		93
Change in demographic assumptions	(460)
Remeasurements	315	1,388
Defined benefit plan, ending balance	11,809	7,880	4,372
Fair value of plan assets
Disclosure of net defined benefit liability (asset) [line items]
Defined benefit plan, beginning balance	5,196	2,986
Current service cost	0	0
Impact of plan changes		0
Interest cost / (income)	11	25
Defined benefit plan costs	(11)	(25)
Employee contributions	348	257
Employer contributions	690	515
Transfers from joiners' previous plans	1,451	1,302
Increase (decrease) through changes other than recognized in profit (loss) or remeasurement, net defined benefit liability (asset)	(2,489)	(2,074)
Exchange differences	560	69
Change in financial assumptions		0
Other actuarial losses	0	0
Plan asset gains	10	2
Exchange differences		40
Change in demographic assumptions	0
Remeasurements	10	42
Defined benefit plan, ending balance	$ 8,266	$ 5,196	$ 2,986

Pension obligations - Schedul_2

Pension obligations - Schedule of actuarial assumptions (Details)	Dec. 31, 2020	Dec. 31, 2019
Employee Benefits [Abstract]
Discount rate	0.20%	0.20%
Interest credited on savings accounts	0.20%	0.20%
Future salary increases	1.50%	1.50%
Future pension increases	0.00%	0.00%

Pension obligations - Schedul_3

Pension obligations - Schedule of average life expectancy (Details) - age	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Employee Benefits [Abstract]
Average male life expectancy	22.45	22.61
Average female life expectancy	25.26	25.64

Pension obligations - Schedul_4

Pension obligations - Schedule of sensitivity of defined benefits (Details)	Dec. 31, 2020	Dec. 31, 2019
Discount rate
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase in assumption	0.25%	0.25%
Impact on defined benefit obligation and service cost	(5.00%)	(5.40%)
Decrease in assumption	(0.25%)	(0.25%)
Impact on defined benefit obligation and service cost	5.40%	5.90%
Future salary increases
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase in assumption	0.50%	0.50%
Impact on defined benefit obligation and service cost	0.70%	0.90%
Decrease in assumption	(0.50%)	(0.50%)
Impact on defined benefit obligation and service cost	(0.70%)	(0.90%)
Interest credited on savings accounts
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase in assumption	0.50%	0.50%
Impact on defined benefit obligation and service cost	2.80%	3.20%
Decrease in assumption	(0.50%)	(0.50%)
Impact on defined benefit obligation and service cost	(2.70%)	(3.00%)
Future pension increases
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Increase in assumption	0.50%	0.50%
Impact on defined benefit obligation and service cost	6.70%	7.00%
Decrease in assumption	(0.50%)	(0.50%)
Impact on defined benefit obligation and service cost	(6.00%)	(6.30%)

Pension obligations - Schedul_5

Pension obligations - Schedule of Investments by asset class (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Employee Benefits [Abstract]
Cash	$ 126	$ 155
Bonds	4,658	3,065
Shares	564	329
Real estates and mortgages	2,353	1,303
Alternative investments	565	344
Investments by asset class	$ 8,266	$ 5,196

Pension obligations - Schedul_6

Pension obligations - Schedule of defined benefit plan reserve (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Employee Benefits [Abstract]
Defined benefit plan reserves, beginning balance	$ (2,389)	$ (1,043)
Remeasurements	(305)	(1,346)
Defined benefit plan reserves, beginning balance	$ (2,694)	$ (2,389)

Convertible loans - Narrative (

Convertible loans - Narrative (Details) $ / shares in Units, $ in Thousands	May 19, 2020USD ($)$ / shares	Apr. 24, 2020USD ($)dayborrowingComponent	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Disclosure of detailed information about borrowings [line items]
Cash and cash equivalents, minimum quarterly balance			$ 50,000
Convertible loans, derivatives			73,208	$ 0
Convertible loans, long-term				0
Convertible loans, short-term				0
Loss on change in fair value of derivatives			45,411	$ 0	$ 0
Initial Public Offering
Disclosure of detailed information about borrowings [line items]
Offering price per share (in USD per share) | $ / shares	$ 19
Facility Agreement with Deerfield Partners, L.P.
Disclosure of detailed information about borrowings [line items]
Borrowings, maximum borrowing capacity		$ 115,000
Number of borrowing components | borrowingComponent		2
Borrowings, interest rate		5.95%
Exit fee		2.00%
Cash and cash equivalents, minimum quarterly balance		$ 50,000
Disbursement upon completion of IPO
Disclosure of detailed information about borrowings [line items]
Borrowings, maximum borrowing capacity		65,000
Borrowings	$ 65,000	$ 65,000
Borrowings maturity		5 years
Conversion percentage		130.00%
Convertible loans, derivatives		$ 27,797	51,229
Implied effective interest rate	23.00%
Interest expense on borrowings			4,756
Loans received			38,406
Convertible loans, long-term			34,775
Convertible loans, short-term			3,631
Loss on change in fair value of derivatives			23,432
Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about borrowings [line items]
Borrowings, maximum borrowing capacity		50,000
Borrowings		$ 50,000
Average volume weighted price of common shares		120.00%
Sale of assets greater than enterprise value		50.00%
Acquisition of common shares		50.00%
Convertible loans, derivatives			21,979
Loss on change in fair value of derivatives			$ 21,979
Increase (decrease) in estimated probability of derivative			10.00%
Value of change in derivative			$ 2,198
Disbursement upon receipt of regulatory approval for Lonca | Conversion period one
Disclosure of detailed information about borrowings [line items]
Conversion period, following approval		1 year
Conversion features, percentage in excess		275.00%
Conversion feature, trading days of weighted average price of common shares | day		20
Conversion feature, trading days of weighted average price of common share, consecutive days | day		30
Disbursement upon receipt of regulatory approval for Lonca | Conversion period two
Disclosure of detailed information about borrowings [line items]
Conversion period, following approval		3 years
Conversion features, percentage in excess		175.00%
Disbursement upon receipt of regulatory approval for Lonca | Bottom of range
Disclosure of detailed information about borrowings [line items]
Conversion percentage		81.00%
Disbursement upon receipt of regulatory approval for Lonca | Top of range
Disclosure of detailed information about borrowings [line items]
Conversion percentage		150.00%

Convertible loans - Schedule of

Convertible loans - Schedule of the first tranche (Details) - Disbursement upon completion of IPO - USD ($) $ in Thousands	May 19, 2020	Apr. 24, 2020
Disclosure of detailed information about borrowings [line items]
Borrowings	$ 65,000	$ 65,000
Gross proceeds
Disclosure of detailed information about borrowings [line items]
Borrowings		65,000
Gross proceeds | Embedded derivative
Disclosure of detailed information about borrowings [line items]
Borrowings		27,797
Gross proceeds | Residual loan
Disclosure of detailed information about borrowings [line items]
Borrowings		37,203
Less: transaction costs
Disclosure of detailed information about borrowings [line items]
Borrowings		(3,673)
Less: transaction costs | Embedded derivative
Disclosure of detailed information about borrowings [line items]
Borrowings		(1,571)
Less: transaction costs | Residual loan
Disclosure of detailed information about borrowings [line items]
Borrowings		(2,102)
Net
Disclosure of detailed information about borrowings [line items]
Borrowings		61,327
Net | Embedded derivative
Disclosure of detailed information about borrowings [line items]
Borrowings		26,226
Net | Residual loan
Disclosure of detailed information about borrowings [line items]
Borrowings		$ 35,101

Convertible loans - Valuation o

Convertible loans - Valuation of derivative (Details) - Derivatives	Dec. 31, 2020period$ / shares	Apr. 24, 2020$ / sharesperiod
Written put options (in USD per share) | Disbursement upon completion of IPO
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	24.70	22.10
Written put options (in USD per share) | Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	28.50
Forced Conversion Price (in USD per share) | Disbursement upon completion of IPO
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	67.93	60.78
Forced Conversion Price (in USD per share) | Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	78.38
Share Price (in USD per share) | Disbursement upon completion of IPO
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	32.01	17
Share Price (in USD per share) | Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	32.01
Risk-free interest rate | Disbursement upon completion of IPO
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	0.003	0.004
Risk-free interest rate | Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	0.003
Expected volatility | Disbursement upon completion of IPO
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	0.90	0.82
Expected volatility | Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	0.90
Expected term | Disbursement upon completion of IPO
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations | period	52	61
Expected term | Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations | period	5
Dividend yield | Disbursement upon completion of IPO
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	0	0
Dividend yield | Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	0
Recovery rate | Disbursement upon completion of IPO
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	0.05	0.05
Recovery rate | Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	0.05
Implied bond yield | Disbursement upon completion of IPO
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	0.133	0.210
Implied bond yield | Disbursement upon receipt of regulatory approval for Lonca
Disclosure of detailed information about borrowings [line items]
Key inputs for valuations	0.074

Share-based compensation expe_3

Share-based compensation expense - Narrative (Details)	Apr. 15, 2020$ / sharesshares	Dec. 31, 2020USD ($)shares$ / shares	Dec. 31, 2019USD ($)shares$ / shares	Dec. 31, 2018USD ($)shares	May 19, 2020$ / shares	Nov. 30, 2019shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized		$ 42,928,000	$ 1,117,000	$ 469,000
Sale of stock, price per share (in USD per share) | $ / shares					$ 19
Strike price (in USD per share) | $ / shares			$ 18.75
Number of shares reserved for issue under options and contracts for sale of shares (in shares) | shares		11,700,000
Share-based compensation expense		$ 37,585,000	$ 1,117,000	$ 469,000
Number of shares granted to compensate holders "out-of-the-money" (in shares) | shares		388,333
Awards vested or exercisable (in shares) | shares		244,291
Number of awards outstanding (in shares) | shares		4,276,973	1,020,434	0
Number of awards expired (in shares) | shares		0
Weighted average exercise price of share options exercisable (in USD per share) | $ / shares			$ 18.75
Weighted average remaining life of exercisable shares		8 years 11 months 8 days
Weighted average fair value price at measurement date (in USD per share) | $ / shares		$ 21.27	15.71
Fair value grant date (in USD per share) | $ / shares		$ 28.62	$ 18.75
Award life		10 years
Share Options
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized		$ 33,355,000	$ 348,000	$ 0
Award life		10 years
Share Options | Tranche One
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting		25.00%
Share Options | Tranche Two
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting		25.00%
Share Options | Tranche Three
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting		25.00%
Share Options | Tranche Four
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting		25.00%
Restricted Share Units (RSU)
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized		$ 1,795,000
Vesting period		3 years
Shares vested (in shares) | shares		0
Share Purchase Plan 2013 And Share Purchase Plan 2016
Disclosure of terms and conditions of share-based payment arrangement [line items]
Borrowings settlement (in USD per share) | $ / shares	$ 18.75
Treasury shares (in shares) | shares	597,774
Share Purchase Plan 2016
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized		$ 7,417,000	332,000	361,000
Share Purchase Plan 2016, Borrowing Settlement
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized		6,425,000
Share Purchase Plan 2013
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized		0	0	0
Incentive Plan 2014
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized		$ 361,000	$ 437,000	108,000
Number of common shares transferred to share-based equity plan (in shares) | shares		356,144
Payments for withheld tax and social charges		$ 5,343,000
Strike price (in USD per share) | $ / shares		$ 19
Vesting period			4 years
2019 Equity Incentive Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized		$ 35,150,000	$ 348,000
Vesting period		3 years
Number of shares reserved for issue under options and contracts for sale of shares (in shares) | shares		3,390,148				7,820,000
Share-based compensation expense		$ 35,498,000
2019 Equity Incentive Plan | Share Options
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized		$ 33,355,000	$ 348,000	$ 0

Share-based compensation expe_4

Share-based compensation expense - Schedule of Number of Awards Outstanding and Weighted Average Strike Price (Details)	Dec. 29, 2020shares	Dec. 16, 2020shares	Dec. 14, 2020shares	Dec. 31, 2020shares$ / shares	Dec. 31, 2019shares$ / shares
Share-based Payment Arrangements [Abstract]
Average strike price in USD per share, At the beginning of the year (in USD per share) | $ / shares				$ 18.75	$ 0
Fair value grant date (in USD per share) | $ / shares				28.62	18.75
Average strike price in USD per share, Forfeited (in USD per share) | $ / shares				19.83	0
Average strike price in USD per share, Exercised (in USD per share) | $ / shares				18.75	0
Average strike price in USD per share, At the end of the year (in USD per share) | $ / shares				$ 26.45	$ 18.75
Number of awards, At the beginning of the year (in shares) | shares				1,020,434	0
Number of awards, Granted (in shares) | shares				3,347,766	1,020,434
Number of awards, Forfeited (in shares) | shares				(88,332)	0
Number of awards, Exercised (in shares) | shares	(517)	(517)	(1,861)	(2,895)	0
Number of awards, At the end of the year (in shares) | shares				4,276,973	1,020,434
Weighted average remaining contractual life of outstanding share options				9 years 3 months 14 days	9 years 11 months 15 days

Share-based compensation expe_5

Share-based compensation expense - Schedule of Share Options Expiry Date And Strike Prices (Details)	Dec. 31, 2020shares$ / shares	Dec. 31, 2019shares	Dec. 31, 2018shares
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Number of awards outstanding (in shares)	4,276,973	1,020,434	0
December 9, 2019
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 18.75
Number of awards outstanding (in shares)	985,848
April 1, 2020
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 18.75
Number of awards outstanding (in shares)	213,764
April 29, 2020
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 18.75
Number of awards outstanding (in shares)	1,272,213
May 15, 2020
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 19
Number of awards outstanding (in shares)	366,257
June 4, 2020
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 34.99
Number of awards outstanding (in shares)	341,403
July 1, 2020
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 48.77
Number of awards outstanding (in shares)	84,589
July 20, 2020
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 48.59
Number of awards outstanding (in shares)	490,883
August 3, 2020
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 46.83
Number of awards outstanding (in shares)	61,576
August 17, 2020
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 38.62
Number of awards outstanding (in shares)	135,064
September 1, 2020
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 41.19
Number of awards outstanding (in shares)	125,850
October 1, 2020
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 32.15
Number of awards outstanding (in shares)	101,875
November 2, 2020
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 29.01
Number of awards outstanding (in shares)	40,220
December 1, 2020
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Exercise price of outstanding share options | $ / shares	$ 38.02
Number of awards outstanding (in shares)	57,431

Share-based compensation expe_6

Share-based compensation expense - Schedule of Fair Value Assumptions For Options Granted (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)shares$ / shares	Dec. 31, 2019USD ($)shares$ / shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Weighted average share price (in USD per share)		$ 16.31
Strike price (in USD per share)		$ 18.75
Expected volatility		176.60%
Award life | shares		5.65
Expected dividends | $	$ 0	$ 0
Risk-free interest rate		1.67%
Minimum
Disclosure of terms and conditions of share-based payment arrangement [line items]
Weighted average share price (in USD per share)	$ 15.95
Strike price (in USD per share)	$ 18.75
Expected volatility	80.00%
Award life | shares	5.02
Risk-free interest rate	0.29%
Maximum
Disclosure of terms and conditions of share-based payment arrangement [line items]
Weighted average share price (in USD per share)	$ 48.77
Strike price (in USD per share)	$ 48.77
Expected volatility	206.00%
Award life | shares	6.08
Risk-free interest rate	0.70%

Share-based compensation expe_7

Share-based compensation expense - Schedule of Other Equity Instruments Outstanding (Details) - Restricted Share Units (RSU)	12 Months Ended
	Dec. 31, 2020shares$ / shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of awards, beginning of period (in shares) | shares	0
Number of awards granted (in shares) | shares	149,984
Number of awards, end of period (in shares) | shares	149,984
Weighted average grant date fair value, beginning balance (in USD per share) | $ / shares	$ 0
Weighted average grant date fair value, granted (in USD per share) | $ / shares	46.50
Weighted average grant date fair value, ending balance (in USD per share) | $ / shares	$ 46.50

Share-based compensation expe_8

Share-based compensation expense - Schedule of Share-based Compensation Reserve (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of terms and conditions of share-based payment arrangement [line items]
Reserve of share-based payments, beginning balance	$ 7,862,000	$ 6,745,000	$ 6,276,000
Expense recognized	42,928,000	1,117,000	469,000
Reserve of share-based payments, ending balance	45,447,000	7,862,000	6,745,000
Share Options
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized	33,355,000	348,000	0
Incentive Plan 2014
Disclosure of terms and conditions of share-based payment arrangement [line items]
Incentive Plan 2014	361,000	437,000	108,000
Expense recognized	361,000	437,000	108,000
Tax expense from share-based payment transactions with employees	(5,343,000)	0	0
Share Purchase Plan 2016
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized	7,417,000	332,000	361,000
2019 Equity Incentive Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized	35,150,000	348,000
2019 Equity Incentive Plan | Share Options
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized	33,355,000	348,000	0
2019 Equity Incentive Plan | Restricted Stock Units
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expense recognized	$ 1,795,000	$ 0	$ 0

Share capital - Schedule of Mov

Share capital - Schedule of Movement in share capital (Details) $ / shares in Units, $ in Thousands	Dec. 29, 2020USD ($)shares	Dec. 16, 2020USD ($)shares	Dec. 14, 2020USD ($)shares	Sep. 30, 2020SFr / sharesshares	Sep. 28, 2020USD ($)$ / sharesshares	May 19, 2020USD ($)shares	Apr. 24, 2020SFr / sharesshares	Apr. 16, 2020USD ($)shares	Apr. 15, 2020USD ($)$ / sharesshares	Dec. 19, 2019USD ($)shares	Sep. 02, 2019USD ($)shares	Aug. 22, 2019USD ($)	Jul. 05, 2019USD ($)shares	Jun. 14, 2019USD ($)shares	Jun. 07, 2019USD ($)shares	Feb. 06, 2019USD ($)shares	Dec. 18, 2018USD ($)shares	Dec. 31, 2020USD ($)shares	Dec. 31, 2019USD ($)shares	Dec. 31, 2018USD ($)shares	Dec. 31, 2020SFr / shares	Dec. 29, 2020SFr / shares	Dec. 16, 2020SFr / shares	Dec. 14, 2020SFr / shares	May 19, 2020SFr / shares	May 19, 2020$ / shares	Apr. 16, 2020SFr / shares	Dec. 16, 2019SFr / shares	Sep. 02, 2019SFr / shares	Jul. 05, 2019SFr / shares	Jun. 14, 2019SFr / shares	Jun. 07, 2019SFr / shares	Feb. 06, 2019SFr / shares	Dec. 18, 2018SFr / shares
Disclosure of classes of share capital [line items]
Equity, beginning balance																		$ 111,156	$ 126,243	$ 249,166
Number of shares outstanding, beginning of period (in shares) | shares																		52,096,960	47,825,000	47,375,000
Issue of share capital / capital contributions																			$ 103,392	$ 4
Issue of share capital / capital contributions (in shares) | shares													962,500	25,000	2,700,000	75,000	450,000
Transaction costs, issuance of share capital																			(1,778)	(28)
Transfer from share premium for par value increase																			0
Purchase of treasury shares																			141
Sale of treasury shares																			$ 41
Sale of treasury shares (in shares) | shares										509,460
Shares surrendered to redeem share purchase plan promissory notes																		$ 0
Issuance of shares through capitalization of reserves																		0
Issuance of shares through capitalization of reserves (in shares) | shares								4,777,996
Elimination of fractional holdings (in shares) | shares							51
Issuance of shares to be held as treasury shares																		0
Grant of shares to settle 2014 incentive plan awards																		0
Grant of shares to settle 2014 incentive plan awards (in shares) | shares						356,144
Issuance of shares at initial public offering																		232,668
Issuance of shares at initial public offering (in shares) | shares						12,245,631
Sale of shares under greenshoe option																		34,900
Sale of shares under greenshoe option (in shares) | shares						1,836,844
Transaction costs, initial public offering and greenshoe option																		(23,355)
Issuance of shares at follow-on offering (in shares) | shares					6,000,000
Issuance of shares at follow-on offering																		204,000
Transaction costs, follow-on offering																		(15,084)
Other (in shares) | shares				2,796
Exercise of options																		$ 54
Exercise of options (in shares) | shares	517	517	1,861															2,895	0
Shares surrendered to redeem share purchase plan promissory notes (in shares) | shares									(597,774)
Total transactions with owners																		$ 470,768	$ 102,631	$ 445
Movements during the year (in shares) | shares																		24,624,583	4,271,960	450,000
Equity, ending balance																		$ 335,505	$ 111,156	$ 126,243
Number of shares outstanding, ending of period (in shares) | shares																		76,721,543	52,096,960	47,825,000
Par value per share (value per share) | (per share)				SFr 0.08	$ 34		SFr 0.08		$ 18.75												SFr 0.08	SFr 0.08	SFr 0.08	SFr 0.08	SFr 0.08	$ 19	SFr 0.08	SFr 0.08	SFr 0.08	SFr 0.008	SFr 0.008	SFr 0.008	SFr 0.008	SFr 0.08
Equity Attributable To Share Transactions
Disclosure of classes of share capital [line items]
Equity, beginning balance																		$ 554,183	$ 452,669	$ 452,693
Issue of share capital / capital contributions													$ 26,950	$ 700	$ 75,600	$ 1	$ 4
Transaction costs, issuance of share capital											$ (8)		(306)	$ (13)	(1,432)	(19)	(28)
Sale of treasury shares										$ 41
Issuance of shares at initial public offering						$ 232,668
Sale of shares under greenshoe option						34,900
Transaction costs, initial public offering and greenshoe option						(23,355)
Issuance of shares at follow-on offering					$ 204,000
Transaction costs, follow-on offering					$ (15,084)
Exercise of options	$ 10	$ 10	$ 34
Total transactions with owners																		433,183	101,514	(24)
Equity, ending balance																			554,183	452,669
Issued share capital
Disclosure of classes of share capital [line items]
Equity, beginning balance																		$ 4,361	$ 401	$ 397
Number of shares outstanding, beginning of period (in shares) | shares																		53,337,500	47,825,000	47,375,000
Issue of share capital / capital contributions													$ 7		$ 22	$ 1	$ 4		$ 171	$ 4
Issue of share capital / capital contributions (in shares) | shares													962,500	25,000	2,700,000	75,000	450,000
Transfer from share premium for par value increase												$ 3,789							3,789
Purchase of treasury shares											$ 141
Purchase of treasury shares (in shares) | shares											1,750,000
Issuance of shares through capitalization of reserves								$ 393										$ 393
Issuance of shares through capitalization of reserves (in shares) | shares								4,777,996
Issuance of shares to be held as treasury shares						$ 34												34
Issuance of shares to be held as treasury shares (in shares) | shares						408,873
Issuance of shares at initial public offering						$ 1,007												1,007
Issuance of shares at initial public offering (in shares) | shares						12,245,631
Issuance of shares at follow-on offering (in shares) | shares					6,000,000
Issuance of shares at follow-on offering					$ 519													519
Total transactions with owners																		$ 1,953	$ 3,960	$ 4
Movements during the year (in shares) | shares																		23,432,500	5,512,500	450,000
Equity, ending balance																		$ 6,314	$ 4,361	$ 401
Number of shares outstanding, ending of period (in shares) | shares																		76,770,000	53,337,500	47,825,000
Share premium
Disclosure of classes of share capital [line items]
Equity, beginning balance																		$ 549,922	$ 452,268	$ 452,296
Issue of share capital / capital contributions													$ 26,943	$ 700	$ 75,578				103,221
Transaction costs, issuance of share capital											$ (8)		$ (306)	$ (13)	$ (1,432)	$ (19)	$ (28)		(1,778)	(28)
Transfer from share premium for par value increase												$ (3,789)							(3,789)
Shares surrendered to redeem share purchase plan promissory notes									$ 11,208									11,208
Issuance of shares through capitalization of reserves								$ (393)										(393)
Grant of shares to settle 2014 incentive plan awards						$ (29)												(29)
Issuance of shares at initial public offering						231,661												231,661
Sale of shares under greenshoe option						23,591												23,591
Transaction costs, initial public offering and greenshoe option						(23,355)												(23,355)
Issuance of shares at follow-on offering					203,481													203,481
Transaction costs, follow-on offering					$ (15,084)													(15,084)
Exercise of options	$ 10	$ 10	$ 34															54
Total transactions with owners																		431,134	97,654	(28)
Equity, ending balance																		981,056	549,922	452,268
Treasury shares
Disclosure of classes of share capital [line items]
Equity, beginning balance																		$ (100)	0	0
Number of shares outstanding, beginning of period (in shares) | shares																		(1,240,540)
Purchase of treasury shares											$ (141)								141
Purchase of treasury shares (in shares) | shares											(1,750,000)
Sale of treasury shares										$ 41									41
Sale of treasury shares (in shares) | shares										509,460
Shares surrendered to redeem share purchase plan promissory notes									$ (11,208)									$ (11,208)
Elimination of fractional holdings (in shares) | shares							51
Issuance of shares to be held as treasury shares						$ (34)												(34)
Issuance of shares to be held as treasury shares (in shares) | shares						(408,873)
Grant of shares to settle 2014 incentive plan awards						$ 29												29
Grant of shares to settle 2014 incentive plan awards (in shares) | shares						356,144
Sale of shares under greenshoe option						$ 11,309												11,309
Sale of shares under greenshoe option (in shares) | shares						1,836,844
Other (in shares) | shares				2,796
Exercise of options (in shares) | shares	517	517	1,861
Shares surrendered to redeem share purchase plan promissory notes (in shares) | shares									(597,774)
Total transactions with owners																		$ 96	$ (100)
Movements during the year (in shares) | shares																		1,192,083	(1,240,540)
Equity, ending balance																		$ (4)	$ (100)	$ 0
Number of shares outstanding, ending of period (in shares) | shares																		(48,457)	(1,240,540)

Share capital - Narrative (Deta

Share capital - Narrative (Details) SFr / shares in Units, $ / shares in Units, SFr in Thousands, $ in Thousands

Dec. 31, 2020CHF (SFr)SFr / sharesshares

Dec. 31, 2020USD ($)shares

Dec. 29, 2020SFr / shares

Dec. 16, 2020SFr / shares

Dec. 14, 2020SFr / shares

Sep. 30, 2020SFr / shares

Sep. 28, 2020$ / shares

May 19, 2020SFr / shares

May 19, 2020$ / shares

Apr. 24, 2020SFr / shares

Apr. 16, 2020SFr / shares

Apr. 15, 2020$ / shares

Dec. 16, 2019SFr / shares

Sep. 02, 2019SFr / shares

Jul. 05, 2019SFr / shares

Jun. 14, 2019SFr / shares

Jun. 07, 2019SFr / shares

Feb. 06, 2019SFr / shares

Dec. 18, 2018SFr / shares

Disclosure of classes of share capital [line items]

Number of shares authorized (in shares)

26,000,000

26,000,000

Par value per share (CHF per share) | (per share)

SFr 0.08

SFr 0.08

SFr 0.08

SFr 0.08

SFr 0.08

$ 34

SFr 0.08

$ 19

SFr 0.08

SFr 0.08

$ 18.75

SFr 0.08

SFr 0.08

SFr 0.008

SFr 0.008

SFr 0.008

SFr 0.008

SFr 0.08

Number of shares reserved for exercise of options, other rights to receive shares or conversion rights granted to employees (in shares)

11,700,000

11,700,000

Shares reserved for exercise of options, other rights to receive shares or conversion rights granted to employees | SFr

SFr 936

Shares reserved for exercise of options, other rights to receive shares or conversion rights granted to employees, par value (CHF per share) | SFr / shares

SFr 0.08

Authorised Share Capital

Disclosure of classes of share capital [line items]

Authorised share capital | SFr

SFr 2,080

Number of shares authorized (in shares)

26,000,000

26,000,000

Authorised share capital, remaining | $

$ 2,080

Conditional Share Capital

Disclosure of classes of share capital [line items]

Authorised share capital | SFr

SFr 1,624

Number of shares authorized (in shares)

20,300,000

20,300,000

Par value per share (CHF per share) | SFr / shares

SFr 0.08

Commitments - Schedule of Commi

Commitments - Schedule of Commitments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	$ 350,422	$ 323,973
Development
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	88,013	94,473
Regulatory
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	30,650	38,000
Sales-based
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	231,759	191,500
Pre-clinical
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	223,406	192,290
Pre-clinical | Development
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	53,497	55,290
Pre-clinical | Regulatory
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	11,650	19,000
Pre-clinical | Sales-based
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	158,259	118,000
Phase I
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	116,219	116,115
Phase I | Development
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	23,719	23,615
Phase I | Regulatory
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	19,000	19,000
Phase I | Sales-based
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	73,500	73,500
Phase II
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	10,797	15,568
Phase II | Development
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	10,797	15,568
Phase II | Regulatory
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	0	0
Phase II | Sales-based
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments for potential milestone payments under collaboration agreements	$ 0	$ 0

Commitments - Narrative (Detail

Commitments - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)productCandidate	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Disclosure Of Detailed Information About Commitments [Line Items]
Contractual capital commitments		$ 323,973
Number of product candidates | productCandidate	2
Research and development expenses	$ 142,032	$ 107,537	$ 118,313
Phase II
Disclosure Of Detailed Information About Commitments [Line Items]
Research and development expenses	5,000
Accrued expenses	$ 5,000

Related parties - Narrative (De

Related parties - Narrative (Details)

Oct. 09, 2020$ / sharesshares

Sep. 28, 2020$ / sharesshares

Jun. 04, 2020shares

May 19, 2020$ / sharesshares

Apr. 16, 2020shares

Apr. 15, 2020shares

Jul. 05, 2019shares

Jun. 14, 2019shares

Jun. 07, 2019shares

Feb. 06, 2019shares

Dec. 18, 2018shares

Dec. 31, 2020USD ($)sharessubsidiary$ / shares

Dec. 31, 2019USD ($)shares$ / shares

Dec. 31, 2018USD ($)

Disclosure of transactions between related parties [line items]

Services provided to, related party transactions | $

$ 4,000

$ 4,000

$ 7,000

Services received, related party transactions | $

$ 0

$ 11,000

$ 38,000

Shares surrendered to redeem share purchase plan promissory notes (in shares)

597,774

Issuance of shares through capitalization of reserves (in shares)

4,777,996

Issue of share capital / capital contributions (in shares)

962,500

25,000

2,700,000

75,000

450,000

Number of awards, Granted (in shares)

3,347,766

1,020,434

Strike price (in USD per share) | $ / shares

$ 18.75

Outstanding share capital

2.00%

Amounts payable, related party transactions | $

$ 0

$ 1,000

Amounts receivable, related party transactions | $

$ 0

$ 0

Initial Public Offering

Disclosure of transactions between related parties [line items]

Number of shares issued (in shares)

14,082,475

Offering price per share (in USD per share) | $ / shares

$ 19

Over-Allotment Option

Disclosure of transactions between related parties [line items]

Offering price per share (in USD per share) | $ / shares

$ 34

$ 34

Increase through shares issued under over-allotment option (in shares)

900,000

Class E Shares

Disclosure of transactions between related parties [line items]

Number of shares issued (in shares)

3,687,500

Related parties

Disclosure of transactions between related parties [line items]

Shares surrendered to redeem share purchase plan promissory notes (in shares)

556,799

Issuance of shares through capitalization of reserves (in shares)

1,222,966

Issue of share capital / capital contributions (in shares)

809,107

Auven Therapeutics Holdings, L.P.

Disclosure of transactions between related parties [line items]

Number of subsidiaries provide services to | subsidiary

4

HPWH TH AG | Initial Public Offering

Disclosure of transactions between related parties [line items]

Number of shares issued (in shares)

950,000

Auven Therapeutics GP Ltd | Over-Allotment Option

Disclosure of transactions between related parties [line items]

Number of shares issued (in shares)

900,000

Chairman of the Board of Directors

Disclosure of transactions between related parties [line items]

Number of awards, Granted (in shares)

341,403

1,125,545

Strike price (in USD per share) | $ / shares

$ 18.75

Outstanding share capital

2.00%

Chairman of the Board of Directors | Share Options

Disclosure of transactions between related parties [line items]

Vesting period

3 years

Related parties - Schedule of K

Related parties - Schedule of Key Management Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party [Abstract]
Salaries and other short-term employee benefits	$ 7,690	$ 5,364	$ 4,512
Pension costs	455	407	299
Share-based compensation expenses	16,752	396	341
Other compensation	196	73	183
Key management compensation	$ 25,093	$ 6,240	$ 5,335

Loss per share (Details)

Loss per share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings per share [abstract]
Net loss	$ (246,290)	$ (116,484)	$ (123,096)
Weighted average number of shares in issue (in shares)	65,410,292	49,279,961	46,600,000
Basic and diluted loss per share (in USD per share)	$ (3.77)	$ (2.36)	$ (2.64)

Loss per share - Schedule of Po

Loss per share - Schedule of Potentially Dilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings per share [line items]
Potentially dilutive securities	4,633,419,000	4,921,420,000	4,329,303,000
Incentive Plan 2014
Earnings per share [line items]
Potentially dilutive securities	0	2,074,996,000	1,959,782,000
Share Purchase Plan 2016
Earnings per share [line items]
Potentially dilutive securities	0	2,784,918,000	2,369,521,000
2019 Equity Incentive Plan - Share Options
Earnings per share [line items]
Potentially dilutive securities	2,904,673,000	61,506,000	0
2019 Equity Incentive Plan - RSUs
Earnings per share [line items]
Potentially dilutive securities	63,281,000	0	0
Conversion of the principal amount of convertible loans into the Company's common shares
Earnings per share [line items]
Potentially dilutive securities	1,665,465,000	0	0

Foreign currency exchange rat_2

Foreign currency exchange rate (Details) - $ / £	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effects Of Changes In Foreign Exchange Rates [Abstract]
Closing rate, GBP 1	1.36501	1.3186	1.2690
Weighted average exchange rate, GBP 1	1.28423	1.2747	1.3501

Events after the reporting date

Events after the reporting date (Details) - Entering into significant commitments or contingent liabilities $ in Millions	1 Months Ended
	Jan. 31, 2021USD ($)m²
Disclosure of non-adjusting events after reporting period [line items]
Lease term	10 years
Lease area (in square meters) | m²	1,100
Lease term for which payments are fixed	5 years
Aggregate minimum lease payments over the first five years | $	$ 2.4
Minimum
Disclosure of non-adjusting events after reporting period [line items]
Lease rent escalation percent	2.00%
Maximum
Disclosure of non-adjusting events after reporting period [line items]
Lease rent escalation percent	4.00%