Adaptimmune Therapeutics (ADAP) 10-Q8 Nov 232023 Q3 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2023	Nov. 07, 2023
Cover [Abstract]
Document Type	10-Q
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Document Quarterly Report	true
Entity File Number	001-37368
Entity Registrant Name	ADAPTIMMUNE THERAPEUTICS PLC
Entity Incorporation, State or Country Code	X0
Entity Address, Address Line One	60 Jubilee Avenue, Milton Park
Entity Address, City or Town	Abingdon, Oxfordshire
Entity Address, Country	GB
Entity Address, Postal Zip Code	OX14 4RX
City Area Code	44
Entity Tax Identification Number	00-0000000
Title of 12(b) Security	American Depositary Shares, each representing 6 Ordinary Shares, par value £0.001 per share
Local Phone Number	1235 430000
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Trading Symbol	ADAP
Entity Common Stock, Shares Outstanding		1,362,729,582
Entity Central Index Key	0001621227
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false

UNAUDITED CONDENSED CONSOLIDATE

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 90,059,000	$ 108,033,000
Marketable securities - available-for-sale debt securities	71,669,000	96,572,000
Accounts receivable, net of allowance for expected credit losses of $0 and $0	789,000	7,435,000
Other current assets and prepaid expenses	56,851,000	43,330,000
Total current assets	219,368,000	255,370,000
Restricted cash	3,013,000	1,569,000
Operating lease right-of-use assets, net of accumulated amortization of $11,930 and $9,470	21,302,000	18,019,000
Property, plant and equipment, net of accumulated depreciation of $42,543 and $38,588	52,571,000	53,516,000
Intangible assets, net of accumulated amortization of $5,008 and $4,676	384,000	442,000
Total assets	296,638,000	328,916,000
Current liabilities
Accounts payable	13,922,000	4,753,000
Operating lease liabilities, current	5,081,000	2,728,000
Accrued expenses and other current liabilities	26,831,000	31,215,000
Restructuring provision		2,285,000
Deferred revenue, current	29,312,000	23,520,000
Total current liabilities	75,146,000	64,501,000
Operating lease liabilities, non-current	20,520,000	20,349,000
Deferred revenue, non-current	111,487,000	160,892,000
Other liabilities, non-current	1,356,000	1,296,000
Total liabilities	208,509,000	247,038,000
Stockholders' equity
Common stock - Ordinary shares par value £0.001, 1,702,760,280 authorized and 1,361,595,036 issued and outstanding (2022: 1,282,773,750 authorized and 987,109,890 issued and outstanding)	1,863,000	1,399,000
Additional paid in capital	1,061,420,000	990,656,000
Accumulated other comprehensive gain/(loss)	102,000	(875,000)
Accumulated deficit	(975,256,000)	(909,302,000)
Total stockholders' equity	88,129,000	81,878,000
Total liabilities and stockholders' equity	$ 296,638,000	$ 328,916,000

UNAUDITED CONDENSED CONSOLIDA_2

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) shares	Dec. 31, 2022 USD ($) shares	Sep. 30, 2023 £ / shares	Dec. 31, 2022 £ / shares
UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS
Allowance for expected credit losses	$ 0	$ 0
Operating lease right-of-use assets, accumulated amortization	11,930	9,470
Property, plant and equipment, accumulated depreciation	42,543	38,588
Intangibles, accumulated amortization	$ 5,008	$ 4,676
Common stock, par value \| £ / shares			£ 0.001	£ 0.001
Common stock, shares authorized \| shares	1,702,760,280	1,282,773,750
Common stock, shares issued \| shares	1,361,595,036	987,109,890
Common stock, shares outstanding \| shares	1,361,595,036	987,109,890

UNAUDITED CONDENSED CONSOLIDA_3

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Revenue	$ 7,319,000	$ 7,007,000	$ 60,050,000	$ 16,120,000
Operating expenses
Research and development	(37,788,000)	(33,182,000)	(93,301,000)	(104,674,000)
General and administrative	(16,164,000)	(16,815,000)	(56,634,000)	(48,169,000)
Total operating expenses	(53,952,000)	(49,997,000)	(149,935,000)	(152,843,000)
Operating loss	(46,633,000)	(42,990,000)	(89,885,000)	(136,723,000)
Interest income	2,149,000	324,000	4,368,000	1,019,000
Gain on bargain purchase			22,049,000
Remeasurement on bargain purchase	(106,000)
Other income (expense), net	(324,000)	1,644,000	(494,000)	1,001,000
Loss before income tax expense	(44,914,000)	(41,022,000)	(63,962,000)	(134,703,000)
Income tax expense	(687,000)	(399,000)	(1,992,000)	(1,503,000)
Net loss attributable to ordinary shareholders	$ (45,601,000)	$ (41,421,000)	$ (65,954,000)	$ (136,206,000)
Net loss per ordinary share
Basic (in dollars per share)	$ (0.03)	$ (0.04)	$ (0.06)	$ (0.14)
Diluted (in dollars per share)	$ (0.03)	$ (0.04)	$ (0.06)	$ (0.14)
Weighted average shares outstanding:
Basic (in shares)	1,357,849,656	980,791,114	1,153,791,567	961,354,122
Diluted (in shares)	1,357,849,656	980,791,114	1,153,791,567	961,354,122

UNAUDITED CONDENSED CONSOLIDA_4

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/LOSS
Net loss	$ (45,601)	$ (41,421)	$ (65,954)	$ (136,206)
Other comprehensive (loss)/income, net of tax
Foreign currency translation adjustments, net of tax of $0, and $0	24,359	58,011	(4,830)	122,496
Foreign currency gains (losses) on intercompany loan of a long-term investment nature, net of tax of $0, and $0	(21,321)	(50,489)	4,794	(103,404)
Unrealized holding gains (losses) on available-for-sale debt securities, net of tax of $0, and $0	69	204	926	(1,267)
Reclassification adjustment for gains on available-for-sale debt securities included in net loss, net of tax of $0 and $0	87		87
Total comprehensive loss for the period	$ (42,407)	$ (33,695)	$ (64,977)	$ (118,381)

UNAUDITED CONDENSED CONSOLIDA_5

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/LOSS (Parenthetical) - USD ($)	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/LOSS
Foreign currency translation adjustments, tax	$ 0	$ 0
Foreign currency gains (losses) on intercompany loan of a long-term investment nature, tax	0	0
Unrealized holding gains (losses) on available-for-sale debt securities, tax	0	$ 0
Reclassification adjustment for gains on available-for-sale debt securities included in net loss, tax	$ 0

UNAUDITED CONDENSED CONSOLIDA_6

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CHANGE IN EQUITY - USD ($) $ in Thousands	Common stock	Additional paid in capital	Accumulated other comprehensive (loss) income	Accumulated deficit	Total
Balance at the beginning of the period, shares at Dec. 31, 2021	937,547,934
Balance at the beginning of the period at Dec. 31, 2021	$ 1,337	$ 959,611	$ (11,142)	$ (743,846)	$ 205,960
Increase (Decrease) in Stockholders' Equity
Issuance of shares upon exercise of stock options	$ 5	30			35
Issuance of shares upon exercise of stock options (in shares)	3,318,072
Other comprehensive loss (gain)			1,829		1,829
Share-based compensation expense		5,586			5,586
Net loss				(50,265)	(50,265)
Balance at the end of the period at Mar. 31, 2022	$ 1,342	965,227	(9,313)	(794,111)	163,145
Balance at the end of the period, shares at Mar. 31, 2022	940,866,006
Balance at the beginning of the period, shares at Dec. 31, 2021	937,547,934
Balance at the beginning of the period at Dec. 31, 2021	$ 1,337	959,611	(11,142)	(743,846)	205,960
Increase (Decrease) in Stockholders' Equity
Net loss					(136,206)
Balance at the end of the period at Sep. 30, 2022	$ 1,394	985,312	6,683	(880,052)	113,337
Balance at the end of the period, shares at Sep. 30, 2022	982,719,936
Balance at the beginning of the period, shares at Mar. 31, 2022	940,866,006
Balance at the beginning of the period at Mar. 31, 2022	$ 1,342	965,227	(9,313)	(794,111)	163,145
Increase (Decrease) in Stockholders' Equity
Issuance of shares upon exercise of stock options	$ 1				1
Issuance of shares upon exercise of stock options (in shares)	759,336
Issue of shares under At The Market sales agreement, net of commission and expenses	$ 44	9,932			9,976
Issue of shares under At The Market sales agreement, net of commission and expenses (in shares)	35,134,182
Other comprehensive loss (gain)			8,270		8,270
Share-based compensation expense		5,045			5,045
Net loss				(44,520)	(44,520)
Balance at the end of the period at Jun. 30, 2022	$ 1,387	980,204	(1,043)	(838,631)	141,917
Balance at the end of the period, shares at Jun. 30, 2022	976,759,524
Increase (Decrease) in Stockholders' Equity
Issuance of shares upon exercise of stock options	$ 1	5			6
Issuance of shares upon exercise of stock options (in shares)	1,005,558
Issuance of shares upon completion of public offering, net of issuance costs	$ 6	1,440			1,446
Issuance of shares upon completion of public offering, net of issuance costs (in shares)	4,954,854
Other comprehensive loss (gain)			7,726		7,726
Share-based compensation expense		3,663			3,663
Net loss				(41,421)	(41,421)
Balance at the end of the period at Sep. 30, 2022	$ 1,394	985,312	6,683	(880,052)	$ 113,337
Balance at the end of the period, shares at Sep. 30, 2022	982,719,936
Balance at the beginning of the period, shares at Dec. 31, 2022	987,109,890				987,109,890
Balance at the beginning of the period at Dec. 31, 2022	$ 1,399	990,656	(875)	(909,302)	$ 81,878
Increase (Decrease) in Stockholders' Equity
Issuance of shares upon exercise of stock options	$ 7	1			8
Issuance of shares upon exercise of stock options (in shares)	6,035,574
Issue of shares under At The Market sales agreement, net of commission and expenses	$ 1	187			188
Issue of shares under At The Market sales agreement, net of commission and expenses (in shares)	554,496
Other comprehensive loss (gain)			(910)		(910)
Share-based compensation expense		1,676			1,676
Net loss				1,036	1,036
Balance at the end of the period at Mar. 31, 2023	$ 1,407	992,520	(1,785)	(908,266)	$ 83,876
Balance at the end of the period, shares at Mar. 31, 2023	993,699,960
Balance at the beginning of the period, shares at Dec. 31, 2022	987,109,890				987,109,890
Balance at the beginning of the period at Dec. 31, 2022	$ 1,399	990,656	(875)	(909,302)	$ 81,878
Increase (Decrease) in Stockholders' Equity
Net loss					(65,954)
Balance at the end of the period at Sep. 30, 2023	$ 1,863	1,061,420	102	(975,256)	$ 88,129
Balance at the end of the period, shares at Sep. 30, 2023	1,361,595,036				1,361,595,036
Balance at the beginning of the period, shares at Mar. 31, 2023	993,699,960
Balance at the beginning of the period at Mar. 31, 2023	$ 1,407	992,520	(1,785)	(908,266)	$ 83,876
Increase (Decrease) in Stockholders' Equity
Issuance of shares upon exercise of stock options	$ 1	13			14
Issuance of shares upon exercise of stock options (in shares)	698,778
Issuance of shares upon acquisition of TCR	$ 443	60,320			60,763
Issuance of shares upon acquisition of TCR (in shares)	357,429,306
Other comprehensive loss (gain)			(1,307)		(1,307)
Share-based compensation expense		4,694			4,694
Net loss				(21,389)	(21,389)
Balance at the end of the period at Jun. 30, 2023	$ 1,851	1,057,547	(3,092)	(929,655)	126,651
Balance at the end of the period, shares at Jun. 30, 2023	1,351,828,044
Increase (Decrease) in Stockholders' Equity
Issuance of shares upon exercise of stock options	$ 9	152			161
Issuance of shares upon exercise of stock options (in shares)	6,466,992
Issuance of shares upon completion of public offering, net of issuance costs	$ 3	432			435
Issuance of shares upon completion of public offering, net of issuance costs (in shares)	3,300,000
Other comprehensive loss (gain)			3,194		3,194
Share-based compensation expense		3,289			3,289
Net loss				(45,601)	(45,601)
Balance at the end of the period at Sep. 30, 2023	$ 1,863	$ 1,061,420	$ 102	$ (975,256)	$ 88,129
Balance at the end of the period, shares at Sep. 30, 2023	1,361,595,036				1,361,595,036

UNAUDITED CONDENSED CONSOLIDA_7

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities
Net loss	$ (65,954)	$ (136,206)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	6,647	4,009
Amortization	322	629
Gain on bargain purchase	(22,049)
Share-based compensation expense	8,692	14,294
Unrealized foreign exchange losses/(gains)	709	(2,501)
(Accretion)/amortization on available-for-sale debt securities	(1,595)	2,165
Other	253	765
Changes in operating assets and liabilities:
Increase in receivables and other operating assets	(709)	(29,778)
(Decrease)/increase in payables and other current liabilities	(7,792)	15,200
Decrease in deferred revenue	(44,728)	(12,388)
Net cash used in operating activities	(126,204)	(143,811)
Cash flows from investing activities
Acquisition of property, plant and equipment	(3,854)	(26,081)
Acquisition of intangible assets	(199)	(231)
Cash from acquisition of TCR2 Therapeutics Inc.	45,264
Maturity or redemption of marketable securities	139,243	136,694
Investment in marketable securities	(73,026)	(42,197)
Other	913
Net cash provided by investing activities	108,341	68,185
Cash flows from financing activities
Proceeds from issuance of common stock from offerings, net of commissions and issuance costs	623	11,422
Proceeds from exercise of stock options	183	42
Net cash provided by financing activities	806	11,464
Effect of currency exchange rate changes on cash, cash equivalents and restricted cash	527	(6,791)
Net decrease in cash, cash equivalents and restricted cash	(16,530)	(70,953)
Cash, cash equivalents and restricted cash at start of period	109,602	151,666
Cash, cash equivalents and restricted cash at end of period	$ 93,072	$ 80,713

General

General	9 Months Ended
General	Sep. 30, 2023
General
General	Note 1 — General Adaptimmune Therapeutics plc is registered in England and Wales. Its registered office is 60 Jubilee Avenue, Milton Park, Abingdon, Oxfordshire, OX14 4RX, United Kingdom. Adaptimmune Therapeutics plc and its subsidiaries (collectively “Adaptimmune” or the “Company”) is a clinical-stage biopharmaceutical company primarily focused on providing novel cell therapies to people with cancer. We are a leader in the development of T-cell therapies for solid tumors. The Company’s proprietary platform enables it to identify cancer targets, find and develop cell therapy candidates active against those targets and produce therapeutic candidates for administration to patients. The Company is subject to a number of risks similar to other biopharmaceutical companies in the early stage of clinical development including, but not limited to, the need to obtain adequate additional funding, possible failure of preclinical programs or clinical programs, the need to obtain marketing approval for its cell therapies, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of its cell therapies, the need to develop a reliable commercial manufacturing process, the need to commercialize any cell therapies that may be approved for marketing, and protection of proprietary technology. If the Company does not successfully commercialize any of its cell therapies, it will be unable to generate product revenue or achieve profitability. The Company had an accumulated deficit of $975,256,000 as of September 30, 2023.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2023
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 2 — Summary of Significant Accounting Policies (a) Basis of presentation The condensed consolidated financial statements of Adaptimmune Therapeutics plc and its subsidiaries and other financial information included in this Quarterly Report are unaudited and have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and are presented in U.S. dollars. All significant intercompany accounts and transactions between the Company and its subsidiaries have been eliminated on consolidation. The unaudited condensed consolidated financial statements presented in this Quarterly Report should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K filed with the SEC on March 6, 2023 (the “Annual Report”). The balance sheet as of December 31, 2022 was derived from audited consolidated financial statements included in the Company’s Annual Report but does not include all disclosures required by U.S. GAAP. The Company’s significant accounting policies are described in Note 2 to those consolidated financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from these interim financial statements. However, these interim financial statements include all adjustments, consisting only of normal recurring adjustments, which are, in the opinion of management, necessary to fairly state the results of the interim period. The interim results are not necessarily indicative of results to be expected for the full year. (b) Use of estimates in interim financial statements The preparation of interim financial statements, in conformity with U.S. GAAP and SEC regulations, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the interim financial statements and reported amounts of revenues and expenses during the reporting period. Estimates and assumptions are made in various areas, including in relation to valuation allowances relating to deferred tax assets, revenue recognition, the fair value of assets acquired, liabilities assumed and consideration transferred in business combinations, and estimation of the incremental borrowing rate for operating leases. If actual results differ from the Company’s estimates, or to the extent these estimates are adjusted in future periods, the Company’s results of operations could either benefit from, or be adversely affected by, any such change in estimate. (c) Fair value measurements The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. The fair value hierarchy prioritizes valuation inputs based on the observable nature of those inputs. The hierarchy defines three levels of valuation inputs: Level 1 - Quoted prices in active markets for identical assets or liabilities Level 2 - Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly Level 3 - Unobservable inputs that reflect the Company's own assumptions about the assumptions market participants would use in pricing the asset or liability The carrying amounts of the Company’s cash and cash equivalents, restricted cash, accounts receivable, accounts payable and accrued expenses approximate fair value because of the short-term nature of these instruments. The fair value of marketable securities, which are measured at fair value on a recurring basis is detailed in Note 6, Fair value measurements. (d ) Significant concentrations of credit risk The Company held cash and cash equivalents of $90,059,000, marketable securities of $71,669,000 and restricted cash of $3,013,000 as of September 30, 2023. The cash and cash equivalents and restricted cash are held with multiple banks and the Company monitors the credit rating of those banks. The Company maintains cash balances in excess of amounts insured by the Federal Deposit Insurance Corporation in the United States and the U.K. Government Financial Services Compensation Scheme in the United Kingdom. The Company’s investment policy limits investments to certain types of instruments, such as money market instruments, corporate debt securities and commercial paper, places restrictions on maturities and concentration by type and issuer and specifies the minimum credit ratings for all investments and the average credit quality of the portfolio. The Company had two customers during the three months ended September 30, 2023 which are Genentech and GSK, and three during the nine months ended, September 30, 2023, which also includes Astellas. There were accounts receivable of $789,000 as of September 30, 2023 and $7,435,000 as of December 31, 2022. The Company has been transacting with Genentech since 2021, Astellas since 2020 and GSK since 2014, during which time no credit losses have been recognized. As of September 30, 2023, no allowance for expected credit losses is recognized on the basis that the possibility of credit losses arising on its receivables as of September 30, 2023 is considered to be remote. Management analyses current and past due accounts and determines if an allowance for credit losses is required based on collection experience, credit worthiness of customers and other relevant information. The process of estimating the uncollectible accounts involves assumptions and judgments and the ultimate amounts of uncollectible accounts receivable could be in excess of the amounts provided. (e) New accounting pronouncements Adopted in the current period Measurement of credit losses on financial instruments In June 2016, the FASB issued ASU 2016-13 - Financial Instruments - Credit losses, which replaces the incurred loss impairment methodology for financial instruments in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The Company adopted the guidance in the fiscal year beginning January 1, 2023. The guidance must be adopted using a modified-retrospective approach and a prospective transition approach is required for debt securities for which an other-than-temporary impairment had been recognized before the effective date. There was no material impact from the adoption of the guidance on the Company’s Consolidated financial statements. Accounting for Contract Assets and Contract Liabilities from Contracts with Customers In October 2021, the FASB issued ASU 2021-08 – Business Combinations (Topic 805)- Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, which improves the accounting for acquired revenue contracts with customers in a business combination by addressing diversity in and inconsistency related to the following: (1) recognition of an acquired contract liability and (2) payment terms and their effect on subsequent revenue recognized by the acquirer. The amendments in this ASU resolve this inconsistency by requiring that an entity (acquirer) recognize and measure contract assets and liabilities acquired in a business combination in accordance with Topic 606, in contrast to current GAAP which requires that assets acquired and liabilities assumed in a business combination, including contract assets and contract liabilities, are measured at fair value as of the acquisition date. The Company adopted the guidance in the fiscal year beginning January 1, 2023. The amendments in this ASU should be applied prospectively to business combinations occurring on or after the effective date of the amendments. Adoption of the new standard had no impact on the Company’s Consolidated financial statements upon transition. There was also no impact from adopting this standard on the acquisition accounting for TCR 2 (f ) Business combinations The Company determines whether a transaction or other event is a business combination by determining whether the assets acquired and liabilities assumed constitute a business. Business combinations are accounted for by applying the acquisition method as set out by ASC 805 Business combinations For leases acquired in a business combination in which the acquiree is a lessee, the acquirer shall measure the lease liability at the present value of the remaining lease payments, as if the acquired lease were a new lease of the acquirer at the acquisition date. The right-of-use asset shall be measured at the same amount as the lease liability, adjusted to reflect favorable or unfavorable terms of the lease when compared with market terms. For leases in which the acquired entity is a lessee, the Company has elected not to recognize assets or liabilities at the acquisition date for leases that, at the acquisition date, have a remaining lease term of 12 months or less. Goodwill is measured as the excess of the consideration transferred in the business combination over the net acquisition date amounts of the identifiable assets acquired and the liabilities assumed. If instead the net acquisition date amounts of the identifiable assets acquired and the liabilities assumed exceeds the consideration transferred, a gain on bargain purchase is recognized in the Consolidated Statement of Operations. The consideration transferred in a business combination is measured as the sum of the fair values of the assets transferred by the acquiring entity, the liabilities incurred by the acquiring entity to former owners of the acquired entity, and the equity interests issued by the acquiring entity. The results of operations of businesses acquired by the Company are included in the Company’s Consolidated Statement of Operations as of the respective acquisition date. Where the acquiring entity exchanges its share-based payment awards for awards held by grantees of the acquiree, such exchanges are treated as a modification of share-based payment awards and are referred to as replacement awards. The replacement awards are measured as of the acquisition date and the portion of the fair-value-based measure of the replacement award that is attributable to pre-combination vesting is considered part of the consideration transferred. For awards with service-based vesting conditions only, the amount attributable to pre-combination vesting is the fair-value-based measure of the acquiree award multiplied by the ratio of the employee’s pre-combination service period to the greater of the total service period of the original service period of the acquiree award. Acquisition-related costs, including advisory, legal and other professional fees and administrative fees are expensed as incurred except for the costs of issuing equity securities, which are recognized as a reduction to the amounts recognized in the Statement of Changes in Equity for the respective equity issuance.

Revenue

Revenue	9 Months Ended
Revenue	Sep. 30, 2023
Revenue
Revenue	Note 3 — Revenue The Company had two revenue-generating contracts with customers in the three months ended September 30, 2023 and three in the nine months ended September 30, 2023, compared to three in the three and nine months ended September 30, 2022: a collaboration agreement with Astellas that was terminated as of March 6, 2023, a strategic collaboration and license agreement with Genentech and a termination and transfer agreement with GSK that was effective on April 6, 2023. The original collaboration and license agreement with GSK was terminated in 2022. Revenue comprises the following categories (in thousands): Three months ended Nine months ended September 30, September 30, 2023 2022 2023 2022 Development revenue $ 7,319 $ 7,007 $ 60,050 $ 16,120 $ 7,319 $ 7,007 $ 60,050 $ 16,120 Deferred revenue decreased by $43,613,000 from $184,412,000 at December 31, 2022 to $140,799,000 at September 30, 2023 primarily due to revenue recognized during the quarter. This was partially offset by payments of $9,613,000 and $3,727,000 from GSK in the second and third quarters of 2023, respectively, and a $1,143,000 increase caused by the change in the exchange rate between pound sterling and the U.S. dollar from £1.00 to $1.21 at December 31, 2022 to £1.00 to $1.22 at September 30, 2023. As of December 31, 2022, there was deferred revenue of $184,412,000 of which $59,375,000 was recognized as revenue in the nine months ended September 30, 2023. The aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements as of September 30, 2023 was $305,197,000. The Genentech Collaboration and License Agreement The amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the Genentech agreement as of September 30, 2023 was $268,588,000. Of this amount $164,158,000 is allocated to the research services and rights granted for the initial ‘off-the-shelf’ collaboration targets, $85,435,000 is allocated to the research services and rights granted for the personalized therapies, $12,821,000 is allocated to the material rights to designate the additional ‘off-the-shelf’ collaboration targets, $4,939,000 is allocated to the material right for the first option to extend the research term and $1,235,000 is allocated to the material right for the option to extend the research term a second time. The Company expects to satisfy the performance obligations relating to the initial ‘off-the-shelf’ collaboration targets and the personalized therapies as development progresses and recognizes revenue based on an estimate of the percentage of completion of the project determined based on the costs incurred on the project as a percentage of the total expected costs. The Company expects to satisfy the performance obligations relating to the material rights to designate additional ‘off-the-shelf’ collaboration targets from the point that the options are exercised and then as development progresses, in line with the initial ‘off-the-shelf’ collaboration targets, or at the point in time that the rights expire. The Company expects to satisfy the performance obligations relating to the material rights to extend the research term from the point that the options are exercised and then over the period of the extension, or at the point in time that the rights expire. The Astellas Collaboration Agreement The Company and Universal Cells mutually agreed to terminate the Astellas Collaboration Agreement as of March 6, 2023 (the “Termination Date”). In connection with the termination, all licenses and sublicenses granted to either party pursuant to the Collaboration Agreement ceased as of the Termination Date. There were no termination penalties in connection with the termination; however the Company is still entitled to receive reimbursement for research and development work performed up to and including a period of 30 days after the Termination Date. The Company originally satisfied the performance obligations relating to the three co-development targets as development progresses and recognized revenue based on an estimate of the percentage of completion of the project determined based on the costs incurred on the project as a percentage of the total expected costs. The Company originally determined that the performance obligations relating to the two independent Astellas targets would be recognized at a point-in-time, upon commencement of the licenses in the event of nomination of the target, since they were right-to-use licenses. The termination was accounted for as a contract modification on a cumulative catch-up basis. No performance obligations were identified as a result of the modification as there were no further goods or services to be provided by the Company and the modification resulted in the remaining unsatisfied and partially satisfied performance obligations under the collaboration becoming fully satisfied. The aggregate transaction price of the contract modification was $42,365,000 which included the remaining deferred income that had not been recognized as revenue as of the date of the modification and variable consideration from the remaining reimbursement income to be billed under the collaboration at the end of the 30 day period after the Effective Date. The transaction price of the modification was recognized in full in March 2023 and there is no remaining transaction price allocated to performance obligations that are unsatisfied or partially satisfied under, no remaining deferred income relating to, the agreement as of September 30, 2023 and no revenue was recognized in the three months ended September 30, 2023. The GSK Collaboration and License Agreement The GSK Collaboration and License Agreement consisted of multiple performance obligations, including the development of a third target, which was the only performance obligation for which revenue was recognized in 2022. The collaboration was terminated by GSK in October 2022 (effective December 23, 2022). A further amendment to the collaboration agreement was entered into on December 19, 2022 for the deletion of certain provisions relating to GSK’s post termination manufacturing and supply obligations and payment of £5,000,000 by GSK to Adaptimmune. The aggregate transaction price of the contract modification was $6,500,000, which was recognized as revenue on the date of the modification. No revenue was recognized in relation to the GSK Collaboration and License Agreement in 2023. The GSK Termination and Transfer Agreement On April 6, 2023, the Company and GSK entered into a Termination and Transfer Agreement (the “Termination and Transfer Agreement”) regarding the return of rights and materials comprised within the PRAME and NY-ESO cell therapy programs. The parties will work collaboratively to ensure continuity for patients in ongoing lete-cel clinical trials forming part of the NY-ESO cell therapy program. As part of the agreement, sponsorship and responsibility for the ongoing IGNYTE and long-term follow-up (“LTFU”) trials relating to the NY-ESO cell therapy program will transfer to Adaptimmune. In return for this, Adaptimmune received an upfront payment of £7.5 million in June 2023 following the signing of the agreement and a milestone payment if £3 million in September 2023. Further milestone payments totalling £19.5 million will be due in relation to successive stages of transfer of the trials. The Company determined that GSK is a customer and has accounted for the agreement under ASC 606 Revenue from Contracts with Customers The aggregate transaction price at inception of the agreement was $37,335,000 comprising the total £30,000,000 upfront and milestone payments. No value was ascribed to non-cash consideration and there was no variable consideration identified. The aggregate transaction price is allocated to the performance obligations depending on the relative standalone selling price of the performance obligations. In determining the best estimate of the relative standalone selling price, the Company considered the internal pricing objectives it used in negotiating the contract, together with internal data regarding the expected costs and a standard margin on those costs, for completing the trials. The amount of the transaction price allocated to the performance obligation is recognized as or when the Company satisfies the performance obligation. The Company expects to satisfy the IGNYTE performance obligation as sponsorship of the active trials that make up the IGNYTE trial transfers, based on the number of patients transferring to the Company in each trial. The Company considers that this depicts the progress of the transfer of sponsorship of the IGNYTE trial to the Company, as each individual trial comprising IGNYTE transferred represents the transfer of a portion of the sponsorship for IGNYTE. The Company expects to satisfy the LTFU performance obligation as sponsorship of the trials that make up the LTFU trial transfers, including trials for potential future patients transferring to the LTFU trial from the IGNYTE trial, based on the number of active and potential patients transferring in each trial. The Company considers that this depicts the progress of the transfer of sponsorship of the LTFU trial to the Company, as each individual trial comprising LTFU transferred represents the transfer of a portion of sponsorship for the LTFU trial and the sponsorship of patients transferring from IGNYTE in future is part of the promise to take on the overall LTFU trial. No revenue was recognized for the agreement in the three and nine months ended September 30, 2023. The amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreement as of September 30, 2023 was $36,609,000, of which $20,501,000 is allocated to the IGNYTE performance obligation and $16,108,000 is allocated to the LTFU performance obligation.

Loss per share

Loss per share	9 Months Ended
Loss per share	Sep. 30, 2023
Loss per share
Loss per share	Note 4 — Loss per share The following tables reconcile the numerator and denominator in the basic and diluted loss per share computation (in thousands): Three months ended Nine months ended September 30, September 30, 2023 2022 2023 2022 Numerator for basic and diluted loss per share Net loss attributable to ordinary shareholders $ (45,601) $ (41,421) $ (65,954) $ (136,206) Net loss attributable to ordinary shareholders used for basic and diluted loss per share $ (45,601) $ (41,421) $ (65,954) $ (136,206) Three months ended Nine months ended September 30, September 30, 2023 2022 2023 2022 Denominator for basic loss per share - Weighted average shares outstanding 1,357,849,656 980,791,114 1,153,791,567 961,354,122 The dilutive effect of 200,370,627 and 152,427,845 stock options outstanding as of September 30, 2023 and 2022 respectively have been excluded from the diluted loss per share calculation for the three and nine months ended September 30, 2023 and 2022 because they would have an antidilutive effect on the loss per share for the period.

Accumulated other comprehensive

Accumulated other comprehensive loss	9 Months Ended
Accumulated other comprehensive loss	Sep. 30, 2023
Accumulated other comprehensive loss.
Accumulated other comprehensive loss	Note 5 — Accumulated other comprehensive (loss)/income The Company reports foreign currency translation adjustments and the foreign exchange gain or losses arising on the revaluation of intercompany loans of a long-term investment nature within Other comprehensive (loss) income. Unrealized gains and losses on available-for-sale debt securities are also reported within Other comprehensive (loss) income until a gain or loss is realized, at which point they are reclassified to Other (expense) income, net in the Condensed Consolidated Statement of Operations. The following tables show the changes in Accumulated other comprehensive (loss) income (in thousands): Accumulated Accumulated Total foreign unrealized accumulated currency (losses) gains on other translation available-for-sale comprehensive adjustments debt securities (loss) income Balance at January 1, 2023 $ 55 $ (930) $ (875) Foreign currency translation adjustments (16,908) — (16,908) Foreign currency gains on intercompany loan of a long-term investment nature, net of tax of $0 15,526 — 15,526 Unrealized holding gains on available-for-sale debt securities, net of tax of $0 — 472 472 Balance at March 31, 2023 $ (1,327) $ (458) $ (1,785) Foreign currency translation adjustments (12,281) — (12,281) Foreign currency gains on intercompany loan of a long-term investment nature, net of tax of $0 10,589 — 10,589 Unrealized holding gains on available-for-sale debt securities, net of tax of $0 — 385 385 Balance at June 30, 2023 $ (3,019) $ (73) $ (3,092) Foreign currency translation adjustments 24,359 — 24,359 Foreign currency losses on intercompany loan of a long-term investment nature, net of tax of $0 (21,321) — (21,321) Unrealized holding gains on available-for-sale debt securities, net of tax of $0 — 69 69 Reclassification from accumulated other comprehensive (loss) income of gains on available-for-sale debt securities included in net loss, net of tax of $0 — 87 87 Balance at September 30, 2023 $ 19 $ 83 $ 102 Accumulated Accumulated Total foreign unrealized accumulated currency (losses) on other translation available-for-sale comprehensive adjustments debt securities (loss) income Balance at January 1, 2022 $ (10,785) $ (357) (11,142) Foreign currency translation adjustments 16,792 — 16,792 Foreign currency losses on intercompany loan of a long-term investment nature, net of tax of $0 (13,808) — (13,808) Unrealized holding losses on available-for-sale debt securities, net of tax of $0 — (1,155) (1,155) Balance at March 31, 2022 $ (7,801) $ (1,512) $ (9,313) Foreign currency translation adjustments 47,694 — 47,694 Foreign currency losses on intercompany loan of a long-term investment nature, net of tax of $0 (39,108) — (39,108) Unrealized holding losses on available-for-sale debt securities, net of tax of $0 — (316) (316) Balance at June 30, 2022 $ 785 $ (1,828) $ (1,043) Foreign currency translation adjustments 58,011 — 58,011 Foreign currency losses on intercompany loan of a long-term investment nature, net of tax of $0 (50,489) — (50,489) Unrealized holding gains on available-for-sale debt securities, net of tax of $0 — 204 204 Balance at September 30, 2022 $ 8,307 $ (1,624) $ 6,683

Fair value measurements

Fair value measurements	9 Months Ended
Fair value measurements	Sep. 30, 2023
Fair value measurements
Fair value measurements	Note 6 — Fair value measurements Assets and liabilities measured at fair value on a recurring basis based on Level 1, Level 2, and Level 3 fair value measurement criteria as of September 30, 2023 are as follows (in thousands): Fair value measurements using September 30, Level 1 Level 2 Level 3 2023 Assets classified as cash equivalents: U.S. Treasury securities $ 7,979 $ — $ 7,979 $ — Assets classified as available-for-sale debt securities: Agency bonds $ 2,981 — 2,981 — Corporate debt securities $ 8,817 $ 8,817 $ — $ — U.S. Treasury securities $ 59,871 — $ 59,871 — $ 71,669 $ 8,817 $ 62,852 $ — The Company estimates the fair value of available-for-sale debt securities with the aid of a third party valuation service, which uses actual trade and indicative prices sourced from third-party providers on a daily basis to estimate the fair value. If observed market prices are not available (for example securities with short maturities and infrequent secondary market trades), the securities are priced using a valuation model maximizing observable inputs, including market interest rates.

Marketable securities - availab

Marketable securities - available-for-sale debt securities	9 Months Ended
Marketable securities - available-for-sale debt securities	Sep. 30, 2023
Marketable securities - available-for-sale debt securities
Marketable securities - available-for-sale debt securities	Note 7 — Marketable securities – available-for-sale debt securities As of September 30, 2023, the Company has the following investments in marketable securities (in thousands): Gross Gross Aggregate Remaining Amortized unrealized unrealized estimated contractual maturity cost gains losses fair value Cash equivalents: U.S. Treasury securities Less than 3 months 7,978 1 — 7,979 $ 7,978 $ 1 $ — $ 7,979 Available-for-sale debt securities: Corporate debt securities Less than 3 months $ 8,824 $ — $ (7) $ 8,817 U.S. Treasury securities Less than 3 months 59,780 94 (3) 59,871 Agency bonds Less than 3 months 2,984 — (3) 2,981 $ 71,588 $ 94 $ (13) $ 71,669 The aggregate fair value (in thousands) and number of securities held by the Company (including those classified as cash equivalents) in an unrealized loss position as of September 30, 2023 and December 31, 2022 are as follows: September 30, 2023 December 31, 2022 Fair market value of investments in an unrealized loss position Number of investments in an unrealized loss position Unrealized losses Fair market value of investments in an unrealized loss position Number of investments in an unrealized loss position Unrealized losses Marketable securities in a continuous loss position for 12 months or longer: Corporate debt securities $ 2,377 1 $ (6) $ 74,481 16 $ (679) Agency bond — — — 4,854 1 (154) Marketable securities in a continuous loss position for less than 12 months: Corporate debt securities $ 6,440 2 $ (1) $ 11,283 2 $ (97) U.S. Treasury securities 14,894 5 (3) — — — Agency bond 2,981 1 (3) — — — $ 26,692 9 $ (13) $ 90,618 19 $ (930) As of September 30, 2023, no allowance for expected credit losses has been recognized in relation to securities in an unrealized loss position. This is because the impairments are not severe, do not represent a significant proportion of the total fair market value of the investments and all securities have an investment-grade credit rating. Furthermore, the Company does not intend to sell the debt securities in an unrealized loss position, believes that it has the ability to hold the debt securities to maturity, and it is currently unlikely that the Company will be required to sell these securities before the recovery of the amortized cost.

Other current assets

Other current assets	9 Months Ended
Other current assets	Sep. 30, 2023
Other current assets
Other current assets	Note 8 — Other current assets Other current assets consisted of the following (in thousands): September 30, December 31, 2023 2022 Research and development credits receivable $ 40,533 $ 30,162 Prepayments 11,973 9,472 Clinical materials 1,290 1,279 VAT receivable 1,372 490 Other current assets 1,683 1,927 $ 56,851 $ 43,330

Operating Leases

Operating Leases	9 Months Ended
Operating Leases	Sep. 30, 2023
Operating leases
Operating leases	Note 9 — Operating leases The Company has operating leases in relation to property for office, manufacturing and research facilities . The following table shows the lease costs for the nine months ended September 30, 2023 and 2022 and the weighted-average remaining lease term and the weighted-average discount rate as at September 30, 2023 and 2022: Nine months ended September 30, 2023 2022 Lease cost: Operating lease cost $ 4,168 $ 3,327 Short-term lease cost 643 253 $ 4,811 $ 3,580 September 30, 2023 2022 Weighted-average remaining lease term - operating leases 5.6 years 7.0 years Weighted-average discount rate - operating leases 8.5% 6.8% The maturities of operating lease liabilities as of September 30, 2023 are as follows (in thousands): Operating leases 2023 $ 1,725 2024 6,826 2025 5,438 2026 4,255 2027 5,488 after 2027 7,385 Total lease payments 31,117 Less: Imputed interest (5,516) Present value of lease liability $ 25,601 The Company has operating leases in relation to property for office, manufacturing and research facilities. On June 1, 2023, as part of the acquisition of TCR 2 2 The third lease had a remaining lease term of less than 12 months as of June 1, 2023, and the Company elected not to recognize a lease liability or right-of-use asset as of June 1, 2023. The rent associated with this lease will be recognized on a straight-line basis over the remainder of the lease term. The maximum lease term without activation of termination options is to 2041.

Accrued expenses and other curr

Accrued expenses and other current liabilities	9 Months Ended
Accrued expenses and other current liabilities	Sep. 30, 2023
Accrued expenses and other current liabilities
Accrued expenses and other current liabilities	Note 10 — Accrued expenses and other current liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, December 31, 2023 2022 Accrued clinical and development expenditure $ 13,208 $ 16,749 Accrued employee expenses 11,047 8,232 Other accrued expenditure 2,504 4,079 Other 72 2,155 $ 26,831 $ 31,215

Contingencies and commitments

Contingencies and commitments	9 Months Ended
Contingencies and commitments	Sep. 30, 2023
Contingencies and commitments
Contingencies and commitments	Note 11 — Contingencies and commitments Universal Cells Research, Collaboration and License Agreement and Co-development and Co-commercialization agreement On November 25, 2015, the Company entered into a Research, Collaboration and License Agreement relating to gene editing and Human Leukocyte Antigen (“HLA”) engineering technology with Universal Cells, Inc. (“Universal Cells”). The Company paid an upfront license and start-up fee of $2,500,000 to Universal Cells in November 2015, a milestone payment of $3,000,000 in February 2016 and further milestone payments of $200,000 and $900,000 were made in the years ended December 31, 2018 and 2017, respectively. The agreement was amended and re-stated as of January 13, 2020, primarily to reflect changes to the development plan agreed between the parties. The agreement was further amended as of July 22, 2022, primarily to make certain changes to development milestones and to agree on the status thereof, as agreed between the parties. Following the amendment, milestone payments of $500,000, $600,000 and $400,000 were made in the year ended December 31, 2022. No remaining milestones have been accrued as of September 30, 2023. The upfront license and start-up fee and milestone payments were expensed to Research and development when incurred. This Agreement was terminated by notice on January 27, 2023, effective 30 days following receipt of notice of termination. As a result of termination, all licenses between the parties to the Agreement will cease and each party is required to return all confidential information of the other party. Astellas Collaboration Agreement Under the Astellas Collaboration Agreement, described further in Note 3, if Adaptimmune had unilaterally developed a product with technology contributed by Astellas, Astellas could have been eligible to receive milestones and royalties relating to future commercialization and sales. As a result of the termination of the collaboration, Astellas no longer has the right to receive these milestones or royalties in future. MD Anderson Strategic Alliance On September 26, 2016, the Company announced that it had entered into a multi-year strategic alliance with The University of Texas MD Anderson Cancer Center (“MD Anderson”) designed to expedite the development of T-cell therapies for multiple types of cancer. The Company and MD Anderson are collaborating on a number of studies including clinical and preclinical development of the Company’s SPEAR T-cell therapies and will collaborate on future clinical stage first and second generation SPEAR T-cell therapies across a number of cancers. Under the terms of the agreement, the Company committed at least $19,644,000 to fund studies. Payment of this funding is contingent on mutual agreement to study orders in order for any study to be included under the alliance and the performance of set milestones by MD Anderson. The Company made an upfront payment of $3,412,000 to MD Anderson in the year ended December 31, 2017 and milestone payments of $2,326,000, $3,549,000, $454,000 and $2,326,000 in the years ended December 31, 2018, 2020, 2021, and 2022, respectively. The Company is obligated to make further payments to MD Anderson as certain milestones are achieved. These costs are expensed to research and development as MD Anderson renders the services under the strategic alliance. The agreement may be terminated by either party for material breach by the other party. Individual studies may be terminated for, amongst other things, material breach, health and safety concerns or where the institutional review board, the review board at the clinical site with oversight of the clinical study, requests termination of any study. Where any legal or regulatory authorization is finally withdrawn or terminated, the relevant study will also terminate automatically.

Share-based compensation

Share-based compensation	9 Months Ended
Share-based compensation	Sep. 30, 2023
Share-based compensation
Share-based compensation	Note 12 — Share-based compensation The following table shows the total share-based compensation expense included in the unaudited consolidated statements of operations (in thousands): Three months ended Nine months ended September 30, September 30, 2023 2022 2023 2022 Research and development $ 789 $ 447 $ 2,190 $ 5,003 General and administrative 2,394 3,216 6,506 9,291 $ 3,183 $ 3,663 $ 8,696 $ 14,294 The following table shows information about share options and options which have a nominal exercise price (similar to restricted stock units (RSUs)) granted: Three months ended Nine months ended September 30, September 30, 2023 2022 2023 2022 Number of options over ordinary shares granted 7,082,892 5,996,581 59,070,294 30,608,533 Weighted average fair value of ordinary shares options $ 0.12 $ 0.21 $ 0.12 $ 0.37 Number of additional options with a nominal exercise price granted 465,960 1,866,216 26,480,652 22,916,376 Weighted average fair value of options with a nominal exercise price $ 0.15 $ 0.28 $ 0.27 $ 0.53 The information above includes the impact of 29,639,418 options over ordinary shares and 5,501,196 options with a nominal exercise price granted on June 1, 2023, as replacement awards as part of the acquisition of TCR 2

Stockholders' equity

Stockholders' equity	9 Months Ended
Stockholders' equity	Sep. 30, 2023
Stockholders' equity
Stockholders' equity	Note 13 — Stockholders’ equity On August 10, 2020 the Company entered into a sales agreement with Cowen and Company, LLC (“Cowen”) (the “Sales Agreement”) under which we may from time to time issue and sell American Depositary Shares (“ADSs”) representing our ordinary shares through Cowen in at-the-market (“ATM”) offerings for an aggregate offering price of up to $200 million. As of September 30, 2023, $197,360,000 remained available for sale under the Sales Agreement. On April 8, 2022 the Company entered into a new sales agreement with Cowen (the “2022 Sales Agreement”) under which we may from time to time issue and sell ADSs representing our ordinary shares through Cowen in ATM offerings for an aggregate offering price of up to $200 million. In the nine months ended 30 September, 2023 the Company sold 642,416 ADSs under the agreement representing 3,854,496 ordinary shares resulting in net proceeds to the Company of $596,716 after deducting commissions payable under the 2022 Sales Agreement and estimated issuance costs. As of September 30, 2023, approximately $186,067,867 remained available for sale under the 2022 Sales Agreement.

Restructuring

Restructuring	9 Months Ended
Restructuring	Sep. 30, 2023
Restructuring
Restructuring	Note 14 – Restructuring 2022-23 Restructuring programme On November 8, 2022, the Company announced that in order to extend the Company’s cash runway, it was re-focusing the business on core programs and deprioritizing non-core programs and undertaking a restructuring of the Company including a headcount reduction to be completed in the first quarter of 2023. The redundancy process was completed in the first quarter of 2023 with a reduction of approximately 25% of global headcount. The redundancy packages to be paid to departing staff comprise a combination of contractual termination benefits, relating to payments that arise from terms of employment contracts and statutory redundancy pay, and one-time employee termination benefits that were provided or enhanced specifically for this redundancy process. Due to the structure of the redundancy scheme and the different employment regulations affecting the Company’s U.K. and U.S. employees, some of the expense associated with the one-time employee termination benefits were recognized over the remaining period of employee service to be rendered. Contractual termination benefits and other one-time employee termination benefits were expensed and recognized in the year ended December 31, 2022. All expenses have been recognized in General and administrative expenses in the Statement of Operations. The amounts incurred in relation to the redundancy programme are as follows: One-time Contractual employee Total termination termination restructuring benefits benefits costs Cumulative amount incurred to December 31, 2022 $ 1,171 $ 1,114 $ 2,285 Amount incurred in the three months ended March 31, 2023 and nine months ended September 30, 2023 778 925 1,703 Total amount and cumulative amount incurred to September 30, 2023 $ 1,949 $ 2,039 $ 3,988 The table below is a summary of the changes in the restructuring provision in the Consolidated Balance Sheet in the nine months ended September 30, 2023: One-time Contractual employee Total termination termination restructuring benefits benefits provision Provision at January 1, 2023 $ 1,171 $ 1,114 $ 2,285 Costs incurred and charged to General and administrative expenses 670 947 1,617 Costs paid during the period (1,955) (1,953) (3,908) Adjustments to the liability 108 (22) 86 Effect of foreign exchange rates 6 2 8 Provision at March 31, 2023 $ — $ 88 $ 88 Costs paid during the period — (88) (88) Provision at June 30, 2023 and September 30, 2023 $ — $ — $ — The costs incurred during the period includes the element of one-time employee termination benefits that was recognized over the remaining period of employee service. The costs incurred during the nine months to 30 September 2023 also include an addition to the provision for costs incurred relating to termination benefits paid to the former Chief Commercial Officer, who left employment with the Company in the first quarter of 2023. No impairment losses were recognized as a result of the restructuring. TCR 2 post-acquisition senior leadership severance 2 2 The amounts incurred in relation to these redundancies in the nine months to September 30, 2023, are as follows: Three and nine months ending September 30, 2023 Severance and other cash payments $ 5,655 Accelerated vesting of share-based compensation awards 835 Amount incurred to June 30, 2023 $ 6,490 Accelerated vesting of share-based compensation awards 197 Total and cumulative amount incurred to September 30, 2023 $ 6,687 The expense associated with the accelerated vesting of share-based compensation awards recognized in Research and development and General and administrative expenses in the Consolidated Statement of Operations was $0.2 million and $0.8 million, respectively. The table below is a summary of the changes in the liability in the Consolidated Balance Sheet in the three and nine months ended September 30, 2023: Liability Liability at June 1, 2023 $ 805 Costs incurred and charged to Research and development expenses 1,267 Costs incurred and charged to General and administrative expenses 4,388 Costs paid during the period (4,823) Liability at June 30, 2023 $ 1,637 Costs paid during the period (752) Liability at September 30, 2023 $ 885 The amounts included in the liabilities at June 1, and September 30, 2023 and the cash paid during the period, include amounts relating to accrued payments to these employees for services provided prior to the acquisition of TCR 2

Business combinations

Business combinations	9 Months Ended
Business combinations	Sep. 30, 2023
Business combinations
Business combinations	Note 15 – Business combinations On March 6, 2023 the Company announced entry into a definitive agreement under which it would combine with TCR 2 2 2 The transaction was approved by the Company’s shareholders and TCR 2 2 2 2 2 2 The Company was identified as the acquirer, with TCR 2 The consideration transferred for TCR 2 2 2 Consideration transferred: Fair value of 357,429,306 ordinary shares issued $ 60,763 Fair value of replacement options and RSU-style options granted attributable to pre-combination service: 963 Purchase consideration $ 61,726 Identifiable assets acquired and liabilities assumed: Assets acquired Cash and cash equivalents $ 43,610 Restricted cash 1,654 Marketable securities - available-for-sale debt securities 39,532 Other current assets and prepaid expenses 6,029 Property, plant and equipment 2,712 Operating lease right-of-use assets 5,145 Intangible assets 58 Total assets acquired $ 98,740 Liabilities assumed Accounts payable (6,210) Accrued expenses and other current liabilities (4,537) Operating lease liabilities, current (1,974) Operating lease liabilities, non-current (2,244) Total liabilities assumed $ (14,965) Net assets acquired and liabilities assumed $ 83,775 The fair value of the 357,429,306 ordinary shares issued to TCR 2 The number and fair value of replacement awards of the Company granted to TCR 2 The assets acquired and liabilities assumed were measured based on management’s estimates of the fair value as of the acquisition date, excluding leases. The lease contracts acquired by the Company relate to the rental of office and manufacturing spaces in which TCR 2 2 The table below summarises the calculation for the gain on bargain purchase, recognized in the Gain on bargain purchase line in the Consolidated Statement of Operations: Gain on bargain purchase Purchase consideration $ (61,726) Net assets acquired and liabilities assumed 83,775 Gain on bargain purchase $ 22,049 The transaction resulted in a gain on bargain purchase as the purchase consideration included in the agreement on March 6, 2023 comprising Company ADSs was based on a fixed ratio of 1.5117 of the Company’s ADSs to be issued for each TCR 2 2 Nine months ended Nine months ended September 30, 2023 September 30, 2022 Revenue $ 60,050 $ 16,120 Net loss (129,684) (214,680) The supplemental pro forma earnings for the nine months ended September 30, 2023 were adjusted to exclude the $22.0 million Gain on bargain purchase, the $7.3 million of acquisition-related costs recognized by the Company, as detailed below, and the $9.0 million of acquisition-related costs incurred by TCR 2 2 TCR 2 The Company incurred the following acquisition-related costs that were recognized as an expense in the nine months ended September 30, 2023: Legal, professional and accounting fees $ 5,174 Bankers' fees 2,172 Total acquisition-related costs $ 7,346 All acquisition-related costs that were recognized as an expense were recognized in General and administrative expenses in the Consolidated Statement of Operations. No issuance costs were incurred relating to the issuance of shares to TCR 2

Subsequent events

Subsequent events	9 Months Ended
Subsequent events	Sep. 30, 2023
Subsequent events
Subsequent events	Note 16 – Subsequent events None.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2023
Summary of Significant Accounting Policies
Basis of presentation	(a) Basis of presentation The condensed consolidated financial statements of Adaptimmune Therapeutics plc and its subsidiaries and other financial information included in this Quarterly Report are unaudited and have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and are presented in U.S. dollars. All significant intercompany accounts and transactions between the Company and its subsidiaries have been eliminated on consolidation. The unaudited condensed consolidated financial statements presented in this Quarterly Report should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K filed with the SEC on March 6, 2023 (the “Annual Report”). The balance sheet as of December 31, 2022 was derived from audited consolidated financial statements included in the Company’s Annual Report but does not include all disclosures required by U.S. GAAP. The Company’s significant accounting policies are described in Note 2 to those consolidated financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from these interim financial statements. However, these interim financial statements include all adjustments, consisting only of normal recurring adjustments, which are, in the opinion of management, necessary to fairly state the results of the interim period. The interim results are not necessarily indicative of results to be expected for the full year.
Use of estimates in interim financial statements	(b) Use of estimates in interim financial statements The preparation of interim financial statements, in conformity with U.S. GAAP and SEC regulations, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the interim financial statements and reported amounts of revenues and expenses during the reporting period. Estimates and assumptions are made in various areas, including in relation to valuation allowances relating to deferred tax assets, revenue recognition, the fair value of assets acquired, liabilities assumed and consideration transferred in business combinations, and estimation of the incremental borrowing rate for operating leases. If actual results differ from the Company’s estimates, or to the extent these estimates are adjusted in future periods, the Company’s results of operations could either benefit from, or be adversely affected by, any such change in estimate.
Fair value measurements	(c) Fair value measurements The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. The fair value hierarchy prioritizes valuation inputs based on the observable nature of those inputs. The hierarchy defines three levels of valuation inputs: Level 1 - Quoted prices in active markets for identical assets or liabilities Level 2 - Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly Level 3 - Unobservable inputs that reflect the Company's own assumptions about the assumptions market participants would use in pricing the asset or liability The carrying amounts of the Company’s cash and cash equivalents, restricted cash, accounts receivable, accounts payable and accrued expenses approximate fair value because of the short-term nature of these instruments. The fair value of marketable securities, which are measured at fair value on a recurring basis is detailed in Note 6, Fair value measurements.
Significant concentrations of credit risk	(d ) Significant concentrations of credit risk The Company held cash and cash equivalents of $90,059,000, marketable securities of $71,669,000 and restricted cash of $3,013,000 as of September 30, 2023. The cash and cash equivalents and restricted cash are held with multiple banks and the Company monitors the credit rating of those banks. The Company maintains cash balances in excess of amounts insured by the Federal Deposit Insurance Corporation in the United States and the U.K. Government Financial Services Compensation Scheme in the United Kingdom. The Company’s investment policy limits investments to certain types of instruments, such as money market instruments, corporate debt securities and commercial paper, places restrictions on maturities and concentration by type and issuer and specifies the minimum credit ratings for all investments and the average credit quality of the portfolio. The Company had two customers during the three months ended September 30, 2023 which are Genentech and GSK, and three during the nine months ended, September 30, 2023, which also includes Astellas. There were accounts receivable of $789,000 as of September 30, 2023 and $7,435,000 as of December 31, 2022. The Company has been transacting with Genentech since 2021, Astellas since 2020 and GSK since 2014, during which time no credit losses have been recognized. As of September 30, 2023, no allowance for expected credit losses is recognized on the basis that the possibility of credit losses arising on its receivables as of September 30, 2023 is considered to be remote. Management analyses current and past due accounts and determines if an allowance for credit losses is required based on collection experience, credit worthiness of customers and other relevant information. The process of estimating the uncollectible accounts involves assumptions and judgments and the ultimate amounts of uncollectible accounts receivable could be in excess of the amounts provided.
New accounting pronouncements	(e) New accounting pronouncements Adopted in the current period Measurement of credit losses on financial instruments In June 2016, the FASB issued ASU 2016-13 - Financial Instruments - Credit losses, which replaces the incurred loss impairment methodology for financial instruments in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The Company adopted the guidance in the fiscal year beginning January 1, 2023. The guidance must be adopted using a modified-retrospective approach and a prospective transition approach is required for debt securities for which an other-than-temporary impairment had been recognized before the effective date. There was no material impact from the adoption of the guidance on the Company’s Consolidated financial statements. Accounting for Contract Assets and Contract Liabilities from Contracts with Customers In October 2021, the FASB issued ASU 2021-08 – Business Combinations (Topic 805)- Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, which improves the accounting for acquired revenue contracts with customers in a business combination by addressing diversity in and inconsistency related to the following: (1) recognition of an acquired contract liability and (2) payment terms and their effect on subsequent revenue recognized by the acquirer. The amendments in this ASU resolve this inconsistency by requiring that an entity (acquirer) recognize and measure contract assets and liabilities acquired in a business combination in accordance with Topic 606, in contrast to current GAAP which requires that assets acquired and liabilities assumed in a business combination, including contract assets and contract liabilities, are measured at fair value as of the acquisition date. The Company adopted the guidance in the fiscal year beginning January 1, 2023. The amendments in this ASU should be applied prospectively to business combinations occurring on or after the effective date of the amendments. Adoption of the new standard had no impact on the Company’s Consolidated financial statements upon transition. There was also no impact from adopting this standard on the acquisition accounting for TCR 2
Business combinations	(f ) Business combinations The Company determines whether a transaction or other event is a business combination by determining whether the assets acquired and liabilities assumed constitute a business. Business combinations are accounted for by applying the acquisition method as set out by ASC 805 Business combinations For leases acquired in a business combination in which the acquiree is a lessee, the acquirer shall measure the lease liability at the present value of the remaining lease payments, as if the acquired lease were a new lease of the acquirer at the acquisition date. The right-of-use asset shall be measured at the same amount as the lease liability, adjusted to reflect favorable or unfavorable terms of the lease when compared with market terms. For leases in which the acquired entity is a lessee, the Company has elected not to recognize assets or liabilities at the acquisition date for leases that, at the acquisition date, have a remaining lease term of 12 months or less. Goodwill is measured as the excess of the consideration transferred in the business combination over the net acquisition date amounts of the identifiable assets acquired and the liabilities assumed. If instead the net acquisition date amounts of the identifiable assets acquired and the liabilities assumed exceeds the consideration transferred, a gain on bargain purchase is recognized in the Consolidated Statement of Operations. The consideration transferred in a business combination is measured as the sum of the fair values of the assets transferred by the acquiring entity, the liabilities incurred by the acquiring entity to former owners of the acquired entity, and the equity interests issued by the acquiring entity. The results of operations of businesses acquired by the Company are included in the Company’s Consolidated Statement of Operations as of the respective acquisition date. Where the acquiring entity exchanges its share-based payment awards for awards held by grantees of the acquiree, such exchanges are treated as a modification of share-based payment awards and are referred to as replacement awards. The replacement awards are measured as of the acquisition date and the portion of the fair-value-based measure of the replacement award that is attributable to pre-combination vesting is considered part of the consideration transferred. For awards with service-based vesting conditions only, the amount attributable to pre-combination vesting is the fair-value-based measure of the acquiree award multiplied by the ratio of the employee’s pre-combination service period to the greater of the total service period of the original service period of the acquiree award. Acquisition-related costs, including advisory, legal and other professional fees and administrative fees are expensed as incurred except for the costs of issuing equity securities, which are recognized as a reduction to the amounts recognized in the Statement of Changes in Equity for the respective equity issuance.

Revenue (Tables)

Revenue (Tables)	9 Months Ended
Revenue (Tables)	Sep. 30, 2023
Revenue
Summary of revenue categories	Revenue comprises the following categories (in thousands): Three months ended Nine months ended September 30, September 30, 2023 2022 2023 2022 Development revenue $ 7,319 $ 7,007 $ 60,050 $ 16,120 $ 7,319 $ 7,007 $ 60,050 $ 16,120

Loss per share (Tables)

Loss per share (Tables)	9 Months Ended
Loss per share (Tables)	Sep. 30, 2023
Loss per share
Schedule of numerator and denominator in the basic and diluted loss per share computation	The following tables reconcile the numerator and denominator in the basic and diluted loss per share computation (in thousands): Three months ended Nine months ended September 30, September 30, 2023 2022 2023 2022 Numerator for basic and diluted loss per share Net loss attributable to ordinary shareholders $ (45,601) $ (41,421) $ (65,954) $ (136,206) Net loss attributable to ordinary shareholders used for basic and diluted loss per share $ (45,601) $ (41,421) $ (65,954) $ (136,206) Three months ended Nine months ended September 30, September 30, 2023 2022 2023 2022 Denominator for basic loss per share - Weighted average shares outstanding 1,357,849,656 980,791,114 1,153,791,567 961,354,122

Accumulated other comprehensi_2

Accumulated other comprehensive loss (Tables)	9 Months Ended
Accumulated other comprehensive loss (Tables)	Sep. 30, 2023
Accumulated other comprehensive loss.
Schedule of changes in Accumulated other comprehensive (loss) income	The following tables show the changes in Accumulated other comprehensive (loss) income (in thousands): Accumulated Accumulated Total foreign unrealized accumulated currency (losses) gains on other translation available-for-sale comprehensive adjustments debt securities (loss) income Balance at January 1, 2023 $ 55 $ (930) $ (875) Foreign currency translation adjustments (16,908) — (16,908) Foreign currency gains on intercompany loan of a long-term investment nature, net of tax of $0 15,526 — 15,526 Unrealized holding gains on available-for-sale debt securities, net of tax of $0 — 472 472 Balance at March 31, 2023 $ (1,327) $ (458) $ (1,785) Foreign currency translation adjustments (12,281) — (12,281) Foreign currency gains on intercompany loan of a long-term investment nature, net of tax of $0 10,589 — 10,589 Unrealized holding gains on available-for-sale debt securities, net of tax of $0 — 385 385 Balance at June 30, 2023 $ (3,019) $ (73) $ (3,092) Foreign currency translation adjustments 24,359 — 24,359 Foreign currency losses on intercompany loan of a long-term investment nature, net of tax of $0 (21,321) — (21,321) Unrealized holding gains on available-for-sale debt securities, net of tax of $0 — 69 69 Reclassification from accumulated other comprehensive (loss) income of gains on available-for-sale debt securities included in net loss, net of tax of $0 — 87 87 Balance at September 30, 2023 $ 19 $ 83 $ 102 Accumulated Accumulated Total foreign unrealized accumulated currency (losses) on other translation available-for-sale comprehensive adjustments debt securities (loss) income Balance at January 1, 2022 $ (10,785) $ (357) (11,142) Foreign currency translation adjustments 16,792 — 16,792 Foreign currency losses on intercompany loan of a long-term investment nature, net of tax of $0 (13,808) — (13,808) Unrealized holding losses on available-for-sale debt securities, net of tax of $0 — (1,155) (1,155) Balance at March 31, 2022 $ (7,801) $ (1,512) $ (9,313) Foreign currency translation adjustments 47,694 — 47,694 Foreign currency losses on intercompany loan of a long-term investment nature, net of tax of $0 (39,108) — (39,108) Unrealized holding losses on available-for-sale debt securities, net of tax of $0 — (316) (316) Balance at June 30, 2022 $ 785 $ (1,828) $ (1,043) Foreign currency translation adjustments 58,011 — 58,011 Foreign currency losses on intercompany loan of a long-term investment nature, net of tax of $0 (50,489) — (50,489) Unrealized holding gains on available-for-sale debt securities, net of tax of $0 — 204 204 Balance at September 30, 2022 $ 8,307 $ (1,624) $ 6,683

Fair value measurements (Tables

Fair value measurements (Tables)	9 Months Ended
Fair value measurements (Tables)	Sep. 30, 2023
Fair value measurements
Summary of fair value of assets and liabilities on a recurring basis based on fair value measurement criteria	Assets and liabilities measured at fair value on a recurring basis based on Level 1, Level 2, and Level 3 fair value measurement criteria as of September 30, 2023 are as follows (in thousands): Fair value measurements using September 30, Level 1 Level 2 Level 3 2023 Assets classified as cash equivalents: U.S. Treasury securities $ 7,979 $ — $ 7,979 $ — Assets classified as available-for-sale debt securities: Agency bonds $ 2,981 — 2,981 — Corporate debt securities $ 8,817 $ 8,817 $ — $ — U.S. Treasury securities $ 59,871 — $ 59,871 — $ 71,669 $ 8,817 $ 62,852 $ —

Marketable securities - avail_2

Marketable securities - available-for-sale debt securities (Tables)	9 Months Ended
	Sep. 30, 2023
Marketable securities - available-for-sale debt securities
Schedule of marketable securities	As of September 30, 2023, the Company has the following investments in marketable securities (in thousands): Gross Gross Aggregate Remaining Amortized unrealized unrealized estimated contractual maturity cost gains losses fair value Cash equivalents: U.S. Treasury securities Less than 3 months 7,978 1 — 7,979 $ 7,978 $ 1 $ — $ 7,979 Available-for-sale debt securities: Corporate debt securities Less than 3 months $ 8,824 $ — $ (7) $ 8,817 U.S. Treasury securities Less than 3 months 59,780 94 (3) 59,871 Agency bonds Less than 3 months 2,984 — (3) 2,981 $ 71,588 $ 94 $ (13) $ 71,669
Schedule of aggregate fair value and number of securities held by the Company in an unrealized loss position	The aggregate fair value (in thousands) and number of securities held by the Company (including those classified as cash equivalents) in an unrealized loss position as of September 30, 2023 and December 31, 2022 are as follows: September 30, 2023 December 31, 2022 Fair market value of investments in an unrealized loss position Number of investments in an unrealized loss position Unrealized losses Fair market value of investments in an unrealized loss position Number of investments in an unrealized loss position Unrealized losses Marketable securities in a continuous loss position for 12 months or longer: Corporate debt securities $ 2,377 1 $ (6) $ 74,481 16 $ (679) Agency bond — — — 4,854 1 (154) Marketable securities in a continuous loss position for less than 12 months: Corporate debt securities $ 6,440 2 $ (1) $ 11,283 2 $ (97) U.S. Treasury securities 14,894 5 (3) — — — Agency bond 2,981 1 (3) — — — $ 26,692 9 $ (13) $ 90,618 19 $ (930)

Other current assets (Tables)

Other current assets (Tables)	9 Months Ended
Other current assets (Tables)	Sep. 30, 2023
Other current assets
Summary of other current assets	Other current assets consisted of the following (in thousands): September 30, December 31, 2023 2022 Research and development credits receivable $ 40,533 $ 30,162 Prepayments 11,973 9,472 Clinical materials 1,290 1,279 VAT receivable 1,372 490 Other current assets 1,683 1,927 $ 56,851 $ 43,330

Operating Leases (Tables)

Operating Leases (Tables)	9 Months Ended
Operating Leases (Tables)	Sep. 30, 2023
Operating leases
Schedule of weighted-average remaining lease term and the weighted-average discount rate	Nine months ended September 30, 2023 2022 Lease cost: Operating lease cost $ 4,168 $ 3,327 Short-term lease cost 643 253 $ 4,811 $ 3,580 September 30, 2023 2022 Weighted-average remaining lease term - operating leases 5.6 years 7.0 years Weighted-average discount rate - operating leases 8.5% 6.8%
Schedule of maturities of operating lease liabilities	The maturities of operating lease liabilities as of September 30, 2023 are as follows (in thousands): Operating leases 2023 $ 1,725 2024 6,826 2025 5,438 2026 4,255 2027 5,488 after 2027 7,385 Total lease payments 31,117 Less: Imputed interest (5,516) Present value of lease liability $ 25,601

Accrued expenses and other cu_2

Accrued expenses and other current liabilities (Tables)	9 Months Ended
Accrued expenses and other current liabilities (Tables)	Sep. 30, 2023
Accrued expenses and other current liabilities
Schedule of accrued expenses and other current liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, December 31, 2023 2022 Accrued clinical and development expenditure $ 13,208 $ 16,749 Accrued employee expenses 11,047 8,232 Other accrued expenditure 2,504 4,079 Other 72 2,155 $ 26,831 $ 31,215

Share-based compensation (Table

Share-based compensation (Tables)	9 Months Ended
Share-based compensation (Tables)	Sep. 30, 2023
Share-based compensation
Summary of share-based compensation expense included in the consolidated statements of operations	The following table shows the total share-based compensation expense included in the unaudited consolidated statements of operations (in thousands): Three months ended Nine months ended September 30, September 30, 2023 2022 2023 2022 Research and development $ 789 $ 447 $ 2,190 $ 5,003 General and administrative 2,394 3,216 6,506 9,291 $ 3,183 $ 3,663 $ 8,696 $ 14,294
Summary of all stock option activity	The following table shows information about share options and options which have a nominal exercise price (similar to restricted stock units (RSUs)) granted: Three months ended Nine months ended September 30, September 30, 2023 2022 2023 2022 Number of options over ordinary shares granted 7,082,892 5,996,581 59,070,294 30,608,533 Weighted average fair value of ordinary shares options $ 0.12 $ 0.21 $ 0.12 $ 0.37 Number of additional options with a nominal exercise price granted 465,960 1,866,216 26,480,652 22,916,376 Weighted average fair value of options with a nominal exercise price $ 0.15 $ 0.28 $ 0.27 $ 0.53

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
Restructuring (Tables)	Sep. 30, 2023
Restructuring
Schedule of amounts incurred in relation to the redundancy programme	The amounts incurred in relation to the redundancy programme are as follows: One-time Contractual employee Total termination termination restructuring benefits benefits costs Cumulative amount incurred to December 31, 2022 $ 1,171 $ 1,114 $ 2,285 Amount incurred in the three months ended March 31, 2023 and nine months ended September 30, 2023 778 925 1,703 Total amount and cumulative amount incurred to September 30, 2023 $ 1,949 $ 2,039 $ 3,988
Schedule of changes in the restructuring provision	The table below is a summary of the changes in the restructuring provision in the Consolidated Balance Sheet in the nine months ended September 30, 2023: One-time Contractual employee Total termination termination restructuring benefits benefits provision Provision at January 1, 2023 $ 1,171 $ 1,114 $ 2,285 Costs incurred and charged to General and administrative expenses 670 947 1,617 Costs paid during the period (1,955) (1,953) (3,908) Adjustments to the liability 108 (22) 86 Effect of foreign exchange rates 6 2 8 Provision at March 31, 2023 $ — $ 88 $ 88 Costs paid during the period — (88) (88) Provision at June 30, 2023 and September 30, 2023 $ — $ — $ —
Schedule of amounts incurred in relation to redundancies	The amounts incurred in relation to these redundancies in the nine months to September 30, 2023, are as follows: Three and nine months ending September 30, 2023 Severance and other cash payments $ 5,655 Accelerated vesting of share-based compensation awards 835 Amount incurred to June 30, 2023 $ 6,490 Accelerated vesting of share-based compensation awards 197 Total and cumulative amount incurred to September 30, 2023 $ 6,687
Summary of changes in the liability in the Consolidated Balance Sheet	Liability Liability at June 1, 2023 $ 805 Costs incurred and charged to Research and development expenses 1,267 Costs incurred and charged to General and administrative expenses 4,388 Costs paid during the period (4,823) Liability at June 30, 2023 $ 1,637 Costs paid during the period (752) Liability at September 30, 2023 $ 885

Business combinations (Tables)

Business combinations (Tables)	9 Months Ended
Business combinations (Tables)	Sep. 30, 2023
Business combinations
Summary of the consideration transferred and the amounts of the assets acquired and liabilities assumed recognized at the acquisition date	Consideration transferred: Fair value of 357,429,306 ordinary shares issued $ 60,763 Fair value of replacement options and RSU-style options granted attributable to pre-combination service: 963 Purchase consideration $ 61,726 Identifiable assets acquired and liabilities assumed: Assets acquired Cash and cash equivalents $ 43,610 Restricted cash 1,654 Marketable securities - available-for-sale debt securities 39,532 Other current assets and prepaid expenses 6,029 Property, plant and equipment 2,712 Operating lease right-of-use assets 5,145 Intangible assets 58 Total assets acquired $ 98,740 Liabilities assumed Accounts payable (6,210) Accrued expenses and other current liabilities (4,537) Operating lease liabilities, current (1,974) Operating lease liabilities, non-current (2,244) Total liabilities assumed $ (14,965) Net assets acquired and liabilities assumed $ 83,775
Schedule of calculation for the gain on bargain purchase	Gain on bargain purchase Purchase consideration $ (61,726) Net assets acquired and liabilities assumed 83,775 Gain on bargain purchase $ 22,049
Schedule of amount of revenue and earnings of the combined entity	Nine months ended Nine months ended September 30, 2023 September 30, 2022 Revenue $ 60,050 $ 16,120 Net loss (129,684) (214,680)
Schedule of acquisition-related costs that were recognized as an expense	The Company incurred the following acquisition-related costs that were recognized as an expense in the nine months ended September 30, 2023: Legal, professional and accounting fees $ 5,174 Bankers' fees 2,172 Total acquisition-related costs $ 7,346

General (Details)

General (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
General
Accumulated deficit	$ 975,256	$ 909,302

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Cash, cash equivalents and restricted cash (Details) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Summary of Significant Accounting Policies
Cash and cash equivalents	$ 90,059,000	$ 108,033,000
Marketable securities - available-for-sale debt securities	71,669,000	$ 96,572,000
Restricted cash	$ 3,013,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Accounts receivable (Details)	Sep. 30, 2023 USD ($) customer	Dec. 31, 2022 USD ($)
Accounts receivable
Allowance for doubtful accounts	$ 0
Accounts receivable	789,000	$ 7,435,000
Customer Concentration Risk
Accounts receivable
Accounts receivable	$ 789,000	$ 7,435,000
Customer Concentration Risk \| Astellas, Genentech and GSK Customers
Accounts receivable
Number of customers \| customer	3
Customer Concentration Risk \| Genentech and GSK Customers
Accounts receivable
Number of customers \| customer	2

Revenue - Revenue from contract

Revenue - Revenue from contracts with customers (Details)	3 Months Ended			9 Months Ended		12 Months Ended
Revenue - Revenue from contracts with customers (Details)	Sep. 30, 2023 USD ($) contract	Mar. 31, 2023 USD ($)	Sep. 30, 2022 USD ($) contract	Sep. 30, 2023 USD ($) contract	Sep. 30, 2022 USD ($) contract	Dec. 31, 2022 USD ($)	Jun. 30, 2023 USD ($)
Revenue
Revenue	$ 7,319,000		$ 7,007,000	$ 60,050,000	$ 16,120,000
Number of contracts with customers \| contract	2		3	3	3
Deferred revenue decrease						$ 43,613,000
Deferred revenue		$ 140,799,000				$ 184,412,000
Upfront payment by GSK for Termination and Transfer Agreement							$ 9,613,000
Amount of increase in deferred income caused by the change in the exchange rate		$ 1,143,000
Exchange rate	1.22			1.22		1.21
Milestone payments received	$ 3,727,000
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements	305,197,000			$ 305,197,000
Revenue recognized in the period				59,375,000
Development revenue
Revenue
Revenue	$ 7,319,000		$ 7,007,000	$ 60,050,000	$ 16,120,000

Revenue - Collaboration Agreeme

Revenue - Collaboration Agreement - The Genentech Collaboration and License Agreement (Details)	Sep. 30, 2023 USD ($)
Revenue
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements	$ 305,197,000
Strategic Collaboration and License Agreement
Revenue
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements	268,588,000
Strategic Collaboration and License Agreement \| Research Service Rights Granted for Initial Off the Shelf Collaboration Targets
Revenue
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements	164,158,000
Strategic Collaboration and License Agreement \| Research Service Rights Granted for Personalized Therapies
Revenue
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements	85,435,000
Strategic Collaboration and License Agreement \| Material Right to Designate the Additional Off the Shelf Collaboration Target
Revenue
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements	12,821,000
Strategic Collaboration and License Agreement \| Material Right for First Option Extend the Research Term
Revenue
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements	4,939,000
Strategic Collaboration and License Agreement \| Material Right for Second Option Extend the Research Term
Revenue
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements	$ 1,235,000

Revenue - Collaboration Agree_2

Revenue - Collaboration Agreement - The Astellas Collaboration Agreement (Details)	9 Months Ended
	Sep. 30, 2023 USD ($) item
Revenue
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements	$ 305,197,000
Astellas Collaboration Agreement.
Revenue
Number Of Co Development Target \| item	3
Number of independent targets \| item	2
Aggregate transaction price of the contract modification	$ 42,365,000
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements	$ 0

Revenue - Collaboration Agree_3

Revenue - Collaboration Agreement - The GSK Collaboration and License Agreement (Details)	Sep. 30, 2023 USD ($)	Dec. 19, 2022 USD ($)	Dec. 19, 2022 GBP (£)
Revenue
Amount of remaining deferred income under the collaboration that had not been recognized as revenue	$ 305,197,000
GSK Collaboration And License Agreement
Revenue
Aggregate transaction price of the contract modification		$ 6,500,000
Amount of remaining deferred income under the collaboration that had not been recognized as revenue	$ 0
Payment by GSK due to termination of collaboration \| £			£ 5,000,000

Revenue - Collaboration Agree_4

Revenue - Collaboration Agreement - The GSK Termination and Transfer Agreement (Details)	1 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2023 GBP (£)	Jun. 30, 2023 GBP (£)	Sep. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2023 GBP (£)	Apr. 06, 2023 USD ($)	Apr. 06, 2023 GBP (£)
Revenue
Revenue recognized in the period				$ 59,375,000
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements			$ 305,197,000	305,197,000
GSK Termination and Transfer Agreement
Revenue
Upfront payment received \| £		£ 7,500,000
Milestone payment \| £	£ 3,000,000
Potential milestone payments to be received \| £					£ 19,500,000
Amount of transaction price of the agreement at inception						$ 37,335,000
Upfront and milestone payment receivable \| £							£ 30,000,000
Revenue recognized in the period			0	0
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements			36,609,000	36,609,000
IGNYTE
Revenue
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements			20,501,000	20,501,000
LTFU
Revenue
Aggregate amount of the transaction price that is allocated to performance obligations that are unsatisfied or partially satisfied under the agreements			$ 16,108,000	$ 16,108,000

Loss per share - Basic and dilu

Loss per share - Basic and diluted loss per share (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Numerator for basic and diluted loss per share
Net Income (Loss)	$ (45,601)	$ (21,389)	$ 1,036	$ (41,421)	$ (44,520)	$ (50,265)	$ (65,954)	$ (136,206)
Net loss attributable to ordinary shareholders used for basic profit/(loss) per share	(45,601)			(41,421)			(65,954)	(136,206)
Net loss attributable to ordinary shareholders used for diluted loss per share	$ (45,601)			$ (41,421)			$ (65,954)	$ (136,206)
Denominator for basic and diluted profit/(loss) per share
Denominator for basic loss per share - Weighted average shares outstanding	1,357,849,656			980,791,114			1,153,791,567	961,354,122
Denominator for diluted loss per share	1,357,849,656			980,791,114			1,153,791,567	961,354,122

Loss per share - Antidilutive s

Loss per share - Antidilutive shares (Details) - shares	9 Months Ended
Loss per share - Antidilutive shares (Details) - shares	Sep. 30, 2023	Sep. 30, 2022
Share options
Antidilutive securities
Potentially dilutive equity instruments excluded from the diluted loss per share (in shares)	200,370,627	152,427,845

Accumulated other comprehensi_3

Accumulated other comprehensive loss (Details) - USD ($)	3 Months Ended						9 Months Ended
Accumulated other comprehensive loss (Details) - USD ($)	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated other comprehensive loss
Balance beginning of period			$ (875,000)				$ (875,000)
Foreign currency translation adjustments	$ 24,359,000			$ 58,011,000			(4,830,000)	$ 122,496,000
Foreign currency losses on intercompany loan of a long-term investment nature, net of tax of $0	(21,321,000)			(50,489,000)			4,794,000	(103,404,000)
Unrealized holding gains on available-for-sale debt securities, net of tax of $0	69,000			204,000			926,000	(1,267,000)
Reclassification from accumulated other comprehensive (loss) income of gains on available-for-sale debt securities included in net loss, net of tax of $0	(87,000)						(87,000)
Balance end of period	102,000						102,000
Accumulated other comprehensive loss (paranthetical)
Foreign currency gain on intercompany loan of a long-term investment nature, tax	0	$ 0	0	0	$ 0	$ 0	0	0
Unrealized holding gains on available-for-sale debt securities, tax	0	0	0	0	0	0	0	0
Reclassification from accumulated other comprehensive (loss) income of gains on available-for-sale debt securities included in net loss, tax	0						0
Accumulated foreign currency translation adjustments
Accumulated other comprehensive loss
Balance beginning of period	(3,019,000)	(1,327,000)	55,000	785,000	(7,801,000)	(10,785,000)	55,000	(10,785,000)
Foreign currency translation adjustments	24,359,000	(12,281,000)	(16,908,000)	58,011,000	47,694,000	16,792,000
Foreign currency losses on intercompany loan of a long-term investment nature, net of tax of $0	(21,321,000)	10,589,000	15,526,000	(50,489,000)	(39,108,000)	(13,808,000)
Balance end of period	19,000	(3,019,000)	(1,327,000)	8,307,000	785,000	(7,801,000)	19,000	8,307,000
Accumulated unrealized (losses) gains on available-for-sale debt securities
Accumulated other comprehensive loss
Balance beginning of period	(73,000)	(458,000)	(930,000)	(1,828,000)	(1,512,000)	(357,000)	(930,000)	(357,000)
Unrealized holding gains on available-for-sale debt securities, net of tax of $0	69,000	385,000	472,000	204,000	(316,000)	(1,155,000)
Reclassification from accumulated other comprehensive (loss) income of gains on available-for-sale debt securities included in net loss, net of tax of $0	87,000
Balance end of period	83,000	(73,000)	(458,000)	(1,624,000)	(1,828,000)	(1,512,000)	83,000	(1,624,000)
Accumulated other comprehensive (loss) income
Accumulated other comprehensive loss
Balance beginning of period	(3,092,000)	(1,785,000)	(875,000)	(1,043,000)	(9,313,000)	(11,142,000)	(875,000)	(11,142,000)
Foreign currency translation adjustments	24,359,000	(12,281,000)	(16,908,000)	58,011,000	47,694,000	16,792,000
Foreign currency losses on intercompany loan of a long-term investment nature, net of tax of $0	(21,321,000)	10,589,000	15,526,000	(50,489,000)	(39,108,000)	(13,808,000)
Unrealized holding gains on available-for-sale debt securities, net of tax of $0	69,000	385,000	472,000	204,000	(316,000)	(1,155,000)
Reclassification from accumulated other comprehensive (loss) income of gains on available-for-sale debt securities included in net loss, net of tax of $0	87,000
Balance end of period	$ 102,000	$ (3,092,000)	$ (1,785,000)	$ 6,683,000	$ (1,043,000)	$ (9,313,000)	$ 102,000	$ 6,683,000

Fair value measurements (Detail

Fair value measurements (Details) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Marketable securities:
Available-for-sale securities, Debt Securities, Current, Total	$ 71,669,000	$ 96,572,000
Recurring basis
Marketable securities:
Available-for-sale securities, Debt Securities, Current, Total	71,669,000
Recurring basis \| Corporate debt securities
Marketable securities:
Available-for-sale securities, Debt Securities, Current, Total	8,817,000
Recurring basis \| U.S. Treasury securities
Cash equivalents:
Total Cash Equivalents	7,979,000
Marketable securities:
Available-for-sale securities, Debt Securities, Current, Total	59,871,000
Recurring basis \| Agency bonds
Marketable securities:
Available-for-sale securities, Debt Securities, Current, Total	2,981,000
Recurring basis \| Level 1
Marketable securities:
Available-for-sale securities, Debt Securities, Current, Total	8,817,000
Recurring basis \| Level 1 \| Corporate debt securities
Marketable securities:
Available-for-sale securities, Debt Securities, Current, Total	8,817,000
Recurring basis \| Level 2
Marketable securities:
Available-for-sale securities, Debt Securities, Current, Total	62,852,000
Recurring basis \| Level 2 \| U.S. Treasury securities
Cash equivalents:
Total Cash Equivalents	7,979,000
Marketable securities:
Available-for-sale securities, Debt Securities, Current, Total	59,871,000
Recurring basis \| Level 2 \| Agency bonds
Marketable securities:
Available-for-sale securities, Debt Securities, Current, Total	$ 2,981,000

Marketable securities - Avail_3

Marketable securities - Available-for-sale debt securities (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Debt Securities
Marketable securities
Amortized cost	$ 71,588
Gross unrealized gains	94
Gross unrealized losses	(13)
Aggregate estimated fair value	71,669
Cash equivalents
Marketable securities
Amortized cost	7,978
Gross unrealized gains	1
Aggregate estimated fair value	7,979
Corporate Debt Securities Maturity Period Less Than Three Months \| Debt Securities
Marketable securities
Amortized cost	8,824
Gross unrealized losses	(7)
Aggregate estimated fair value	8,817
U.S. Treasury Securities Maturity Period Less Than Three Months
Marketable securities
Amortized cost	59,780
Gross unrealized gains	94
Gross unrealized losses	(3)
Aggregate estimated fair value	59,871
U.S. Treasury Securities Maturity Period Less Than Three Months \| Cash equivalents
Marketable securities
Amortized cost	7,978
Gross unrealized gains	1
Aggregate estimated fair value	7,979
Agency Bond Maturity Period Less Than Three Months
Marketable securities
Amortized cost	2,984
Gross unrealized losses	(3)
Aggregate estimated fair value	$ 2,981
Maximum \| Corporate Debt Securities Maturity Period Less Than Three Months \| Debt Securities
Marketable securities
Available For Sale Securities Debt Maturity Period	3 months
Maximum \| U.S. Treasury Securities Maturity Period Less Than Three Months
Marketable securities
Available For Sale Securities Debt Maturity Period	3 months
Maximum \| U.S. Treasury Securities Maturity Period Less Than Three Months \| Cash equivalents
Marketable securities
Available For Sale Securities Debt Maturity Period	3 months
Maximum \| Agency Bond Maturity Period Less Than Three Months
Marketable securities
Available For Sale Securities Debt Maturity Period	3 months

Marketable securities - Avail_4

Marketable securities - Available-for-sale debt securities - Unrealized loss position (Details) $ in Thousands	Sep. 30, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Marketable securities
Fair market value of investments in an unrealized loss position	$ 26,692	$ 90,618
Number of investments in an unrealized loss position \| security	9	19
Unrealized losses	$ (13)	$ (930)
Corporate debt securities
Marketable securities
Fair market value of investments in an unrealized loss position, 12 months or longer	2,377	74,481
Fair market value of investments in an unrealized loss position, less than 12 months	$ 6,440	$ 11,283
Number of available-for-sale securities in an unrealized loss position, 12 months or longer \| security	1	16
Number of available-for-sale securities in an unrealized loss position, less than 12 months \| security	2	2
Unrealized losses, 12 months or longer	$ (6)	$ (679)
Unrealized losses, less than 12 months	(1)	(97)
U.S. Treasury securities
Marketable securities
Fair market value of investments in an unrealized loss position, less than 12 months	$ 14,894
Number of available-for-sale securities in an unrealized loss position, less than 12 months \| security	5
Unrealized losses, less than 12 months	$ (3)
Agency bonds
Marketable securities
Fair market value of investments in an unrealized loss position, 12 months or longer		$ 4,854
Fair market value of investments in an unrealized loss position, less than 12 months	$ 2,981
Number of available-for-sale securities in an unrealized loss position, 12 months or longer \| security		1
Number of available-for-sale securities in an unrealized loss position, less than 12 months \| security	1
Unrealized losses, 12 months or longer		$ (154)
Unrealized losses, less than 12 months	$ (3)

Other current assets (Details)

Other current assets (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Other current assets
Research and development credits receivable	$ 40,533	$ 30,162
Prepayments	11,973	9,472
Clinical materials	1,290	1,279
VAT receivable	1,372	490
Other current assets	1,683	1,927
Total	$ 56,851	$ 43,330

Operating Leases (Details)

Operating Leases (Details) $ in Thousands	9 Months Ended
Operating Leases (Details) $ in Thousands	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jun. 01, 2023 lease
Operating leases
Operating lease cost	$ 4,168	$ 3,327
Short-term lease cost	643	253
Total	$ 4,811	$ 3,580
Weighted-average remaining lease term - operating leases	5 years 7 months 6 days	7 years
Weighted-average discount rate - operating leases	8.50%	6.80%
Number of operating leases that were acquired in a business combination for which the acquirees lease classification was retained \| lease			2

Operating Leases - Maturities (

Operating Leases - Maturities (Details) $ in Thousands	Sep. 30, 2023 USD ($)
Maturities of operating lease liabilities
2023	$ 1,725
2024	6,826
2025	5,438
2026	4,255
2027	5,488
after 2027	7,385
Total lease payments	31,117
Less: Imputed interest	(5,516)
Present value of lease liability	$ 25,601

Accrued expenses and other cu_3

Accrued expenses and other current liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Accrued expenses and other current liabilities
Accrued clinical and development expenditure	$ 13,208	$ 16,749
Accrued employee expenses	11,047	8,232
Other accrued expenditure	2,504	4,079
Other	72	2,155
Total	$ 26,831	$ 31,215

Contingencies and commitments -

Contingencies and commitments - Universal Cells Research, Collaboration and License Agreement and Co-development and Co-commercialization agreement (Details) - Collaboration and license agreement - Universal Cells, Inc.	1 Months Ended		12 Months Ended
	Feb. 29, 2016 USD ($)	Nov. 30, 2015 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2023 item	Dec. 31, 2022 USD ($)
Contingencies and commitments
Upfront license and start-up fees		$ 2,500,000
Milestone payments	$ 3,000,000		$ 200,000	$ 900,000
First milestone payment						$ 500,000
Second milestone payment						600,000
Third milestone payment						$ 400,000
Number of remaining milestones accrued \| item					0

Contingencies and commitments_2

Contingencies and commitments - MD Anderson Strategic Alliance (Details) - MD Anderson Strategic Alliance - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2017	Sep. 26, 2016
Contingencies and commitments
Upfront payment					$ 3,412,000
Milestone Payments	$ 2,326,000	$ 454,000	$ 3,549,000	$ 2,326,000
Minimum
Contingencies and commitments
Potential milestone payments						$ 19,644,000

Share-based compensation - Shar

Share-based compensation - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Total share-based compensation expense included in the consolidated statements of operations
Total share-based compensation expense	$ 3,183	$ 3,663	$ 8,696	$ 14,294
Research and development
Total share-based compensation expense included in the consolidated statements of operations
Total share-based compensation expense	789	447	2,190	5,003
General and administrative
Total share-based compensation expense included in the consolidated statements of operations
Total share-based compensation expense	$ 2,394	$ 3,216	$ 6,506	$ 9,291

Share-based compensation - Opti

Share-based compensation - Options (Details) - $ / shares		3 Months Ended		9 Months Ended
Share-based compensation - Options (Details) - $ / shares	Jun. 01, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Number of options over ordinary shares granted (in shares)		7,082,892	5,996,581	59,070,294	30,608,533
Weighted average fair value of ordinary shares options (in dollars per share)		$ 0.12	$ 0.21	$ 0.12	$ 0.37
Number of additional options with a nominal exercise price granted		465,960	1,866,216	26,480,652	22,916,376
Weighted average fair value of options with a nominal exercise price		$ 0.15	$ 0.28	$ 0.27	$ 0.53
Replacement Awards Granted To TCR2 Grantholders
Number of options over ordinary shares granted (in shares)	29,639,418
Number of additional options with a nominal exercise price granted	5,501,196

Stockholders equity - Offerings

Stockholders equity - Offerings (Details) - USD ($)			3 Months Ended				9 Months Ended
Stockholders equity - Offerings (Details) - USD ($)	Apr. 08, 2022	Aug. 10, 2020	Sep. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Sep. 30, 2023
Sales Agreement
Shareholders' equity
Remaining amount under the Sales Agreement							$ 197,360,000
Sales Agreement \| Maximum
Shareholders' equity
Aggregate offering price of ADS shares under At The Market sales agreement		$ 200,000,000
2022 Sales Agreement
Shareholders' equity
Remaining amount under the Sales Agreement							$ 186,067,867
Issuance of shares upon completion of public offering, net of issuance costs (in shares)							3,854,496
Sold shares represented by American Depositary Shares (in shares)							642,416
Net proceeds							$ 596,716
2022 Sales Agreement \| Maximum
Shareholders' equity
Aggregate offering price of ADS shares under At The Market sales agreement	$ 200,000,000
Common stock
Shareholders' equity
Issuance of shares upon completion of public offering, net of issuance costs (in shares)			3,300,000		4,954,854
Number of ordinary shares sold (in shares)				554,496		35,134,182

Restructuring (Details)

Restructuring (Details) - USD ($) $ in Thousands	9 Months Ended
Restructuring (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Restructuring
Restructuring and Related Cost, Cost Incurred to Date	$ 1,703	$ 2,285
Total amount expected to be incurred	$ 3,988
Percent of headcount reduction	25%
Contractual termination benefits
Restructuring
Restructuring and Related Cost, Cost Incurred to Date	$ 778	1,171
Total amount expected to be incurred	1,949
One-time employee termination benefits
Restructuring
Restructuring and Related Cost, Cost Incurred to Date	925	$ 1,114
Total amount expected to be incurred	$ 2,039

Restructuring - Movements in Pr

Restructuring - Movements in Provision (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Mar. 31, 2023	Sep. 30, 2023
Restructuring
Balance at the beginning		$ 2,285	$ 2,285
Costs incurred and charged to General and administrative expenses		1,617
Costs paid during the period	$ (88)	(3,908)
Adjustments to the liability		86
Effect of foreign exchange rates		8
Balance at the end		88
Impairment loss			0
Contractual termination benefits
Restructuring
Balance at the beginning		1,171	1,171
Costs incurred and charged to General and administrative expenses		670
Costs paid during the period		(1,955)
Adjustments to the liability		108
Effect of foreign exchange rates		6
One-time employee termination benefits
Restructuring
Balance at the beginning		1,114	$ 1,114
Costs incurred and charged to General and administrative expenses		947
Costs paid during the period	$ (88)	(1,953)
Adjustments to the liability		(22)
Effect of foreign exchange rates		2
Balance at the end		$ 88

Restructuring - TCR post-acquis

Restructuring - TCR post-acquisition senior leadership severance (Details) - Employee Severance - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2023
Restructuring
Severance and other cash payments		$ 5,655
Accelerated vesting of share-based compensation awards	$ 197	835
Total and cumulative amount incurred	$ 6,687	$ 6,490
Research and development
Restructuring
Accelerated vesting of share-based compensation awards			$ 200,000
General and administrative expenses
Restructuring
Accelerated vesting of share-based compensation awards			$ 800,000

Restructuring - TCR post-acqu_2

Restructuring - TCR post-acquisition senior leadership severance - Change in Liability (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Jun. 30, 2023	Sep. 30, 2023	Mar. 31, 2023
Restructuring
Beginning liability	$ 805	$ 1,637
Costs incurred and charged			$ 1,617
Cost paid during the period	(4,823)	(752)
Ending liability	1,637	$ 885
Research and development
Restructuring
Costs incurred and charged	1,267
General and administrative
Restructuring
Costs incurred and charged	$ 4,388

Business combinations (Details)

Business combinations (Details) - USD ($)			3 Months Ended
Business combinations (Details) - USD ($)	Jun. 01, 2023	May 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Consideration transferred:
Remeasurement on bargain purchase			$ (106,000)
Assets acquired
Operating lease right-of-use assets			21,302,000	$ 18,019,000
Liabilities assumed
Operating lease liabilities, current			(5,081,000)	(2,728,000)
Operating lease liabilities, non-current			$ (20,520,000)	$ (20,349,000)
TCR2 Therapeutics
Merger with TCR2 Therapeutics Inc.
Percentage held following the transaction	25%
Adaptimmune
Merger with TCR2 Therapeutics Inc.
Percentage held following the transaction	75%
TCR2 Therapeutics
Merger with TCR2 Therapeutics Inc.
Shares issued	357,429,306	357,429,306
Percentage of ownership	100%
Market price		$ 1.02
Ordinary share price per share		$ 0.17
Intangible assets relation to lease contracts acquired	$ 0
Consideration transferred:
Fair value of shares issued	60,763,000	$ 60,763,000
Fair value of replacement share options issued	963,000
Purchase consideration	61,726,000
Assets acquired
Cash and cash equivalents	43,610,000
Restricted cash	1,654,000
Marketable securities - available-for-sale debt securities	39,532,000
Other current assets and prepaid expenses	6,029,000
Property, plant and equipment	2,712,000
Operating lease right-of-use assets	5,145,000
Intangible assets	58,000
Total assets acquired	98,740,000
Liabilities assumed
Accounts payable	(6,210,000)
Accrued expenses and other current liabilities	(4,537,000)
Operating lease liabilities, current	(1,974,000)
Operating lease liabilities, non-current	(2,244,000)
Total liabilities assumed	(14,965,000)
Net assets acquired and liabilities assumed	$ 83,775,000

Business combinations - Gain on

Business combinations - Gain on bargain purchase (Details)		9 Months Ended
Business combinations - Gain on bargain purchase (Details)	Jun. 01, 2023 USD ($)	Sep. 30, 2023 USD ($)	May 31, 2023 $ / shares	Mar. 06, 2023 $ / shares
Merger with TCR2 Therapeutics Inc.
Gain on bargain purchase		$ 22,049,000
TCR2 Therapeutics
Merger with TCR2 Therapeutics Inc.
Purchase consideration	$ (61,726,000)
Net assets acquired and liabilities assumed	83,775,000
Gain on bargain purchase	$ 22,049,000	22,000,000
Ratio for issuance of Company's ADSs for each TCR2 stock acquired				1.5117
Closing price of Company's ADS \| $ / shares			$ 1.02	$ 1.32
Amount of TCR2's earnings included in the Company's Consolidated Statement of Operations		$ 23,531,000

Business combinations - Proform

Business combinations - Proforma Information (Details) - USD ($)		3 Months Ended		5 Months Ended	9 Months Ended
	Jun. 01, 2023	Sep. 30, 2023	Sep. 30, 2022	May 31, 2023	Sep. 30, 2023	Sep. 30, 2022
Merger with TCR2 Therapeutics Inc.
Gain on bargain purchase					$ 22,049,000
Share-based compensation expense		$ 3,183,000	$ 3,663,000		8,696,000	$ 14,294,000
TCR2 Therapeutics
Merger with TCR2 Therapeutics Inc.
Revenue					60,050	16,120
Net loss					(129,684)	(214,680)
Acquisition-related costs incurred by TCR2					9,000,000
Gain on bargain purchase	$ 22,049,000				22,000,000
Acquisition-related costs					$ 7,346,000
Share-based compensation expense				$ 1,000,000		$ 8,700,000

Business combinations - Acquisi

Business combinations - Acquisition-related costs (Details) - TCR2 Therapeutics $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Merger with TCR2 Therapeutics Inc.
Legal, professional and accounting fees	$ 5,174
Bankers' fees	2,172
Total acquisition-related costs	7,346
Issuance costs incurred relating to the issuance of shares to TCR2 stockholders	$ 0

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (45,601)	$ (21,389)	$ 1,036	$ (41,421)	$ (44,520)	$ (50,265)	$ (65,954)	$ (136,206)

Insider Trading Arrangements

Insider Trading Arrangements	9 Months Ended
Insider Trading Arrangements	Sep. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false