Adaptimmune Therapeutics (ADAP) 10-Q 1 Aug 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 29, 2019
Document and Entity Information [Abstract]
Entity Central Index Key	0001621227
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2019
Document Transition Report	false
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
Local Phone Number	1235 430000
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	American Depositary Shares, each representing 6 Ordinary Shares, par value £0.001 per share
Trading Symbol	ADAP
Security Exchange Name	NASDAQ
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		630,762,860
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2

UNAUDITED CONDENSED CONSOLIDATE

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 34,574	$ 68,379
Marketable securities - available-for-sale debt securities	98,832	136,755
Accounts receivable, net of allowance for doubtful accounts of $0 and $0	3,809	192
Other current assets and prepaid expenses (including current portion of clinical materials)	37,918	25,769
Total current assets	175,133	231,095
Restricted cash	4,403	4,097
Clinical materials	2,690	3,953
Operating lease right-of-use assets, net of accumulated amortization	21,507
Property, plant and equipment, net of accumulated depreciation of $19,528 (2018: $15,924)	33,722	36,118
Intangibles, net of accumulated amortization	2,066	1,473
Total assets	239,521	276,736
Current liabilities
Accounts payable	4,344	4,083
Operating lease liabilities, current	2,338
Accrued expenses and other accrued liabilities	18,595	20,354
Deferred revenue	3,016
Total current liabilities	28,293	24,437
Operating lease liabilities, non-current	23,666
Other liabilities, non-current	571	5,414
Total liabilities	52,530	29,851
Stockholders' equity
Common stock - Ordinary shares par value ?0.001, 785,857,300 authorized and 630,672,578 issued and outstanding (2018: 701,103,126 authorized and 627,454,270 issued and outstanding)	943	939
Additional paid in capital	581,245	574,208
Accumulated other comprehensive loss	(8,199)	(9,763)
Accumulated deficit	(386,998)	(318,499)
Total stockholders' equity	186,991	246,885
Total liabilities and stockholders' equity	$ 239,521	$ 276,736

UNAUDITED CONDENSED CONSOLIDA_2

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) $ in Thousands	Jun. 30, 2019£ / shares	Jun. 30, 2019USD ($)shares	Dec. 31, 2018£ / shares	Dec. 31, 2018USD ($)shares
UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS
Allowance for doubtful accounts | $		$ 0		$ 0
Property, plant and equipment, accumulated depreciation | $		$ 19,528		$ 15,924
Common stock, par value | £ / shares	£ 0.001		£ 0.001
Common stock, shares authorized		785,857,300		701,103,126
Common stock, shares issued		630,672,578		627,454,270
Common stock, shares outstanding		630,672,578		627,454,270

UNAUDITED CONDENSED CONSOLIDA_3

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue	$ 157	$ 9,038	$ 157	$ 17,234
Operating expenses
Research and development	(25,511)	(26,624)	(47,530)	(52,016)
General and administrative	(10,148)	(11,291)	(21,921)	(22,495)
Total operating expenses	(35,659)	(37,915)	(69,451)	(74,511)
Operating loss	(35,502)	(28,877)	(69,294)	(57,277)
Interest income	757	540	1,709	1,199
Other expense, net	(6,277)	(15,406)	(847)	(8,276)
Loss before income taxes	(41,022)	(43,743)	(68,432)	(64,354)
Income taxes	(65)	(102)	(67)	(229)
Net loss attributable to ordinary shareholders	$ (41,087)	$ (43,845)	$ (68,499)	$ (64,583)
Net loss per ordinary share - Basic and diluted
Basic and diluted (in dollars per share)	$ (0.07)	$ (0.08)	$ (0.11)	$ (0.11)
Weighted average shares outstanding:
Basic and diluted (in shares)	629,355,975	565,197,217	628,655,278	563,804,832
Development revenue
Revenue	$ 157	$ 9,038	$ 157	$ 17,234

UNAUDITED CONDENSED CONSOLIDA_4

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS
Net loss	$ (41,087)	$ (43,845)	$ (68,499)	$ (64,583)
Other comprehensive loss, net of tax
Foreign currency translation adjustments, net of tax of $0, $0, $0 and $0	4,842	6,107	1,299	3,582
Unrealized gains on available-for-sale debt securities
Unrealized holding gains on available-for-sale debt securities, net of tax of $0, $0, $0 and $0	68	5,223	278	1,167
Reclassification adjustment for (gains) losses on available-for-sale debt securities included in net loss, net of tax of $0, $0, $0 and $0	(13)	1,310	(13)	2,473
Total comprehensive loss for the period	$ (36,190)	$ (31,205)	$ (66,935)	$ (57,361)

UNAUDITED CONDENSED CONSOLIDA_5

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS
Foreign currency translation adjustments, tax	$ 0	$ 0	$ 0	$ 0
Unrealized holding gains on available-for-sale debt securities, tax	0	0	0	0
Reclassification adjustment for losses on available-for-sale debt securities included in net loss, tax	$ 0	$ 0	$ 0	$ 0

UNAUDITED CONDENSED CONSOLIDA_6

UNAUDITED CONDENSED CONSOLIDATED STATEMENT OF CHANGE IN EQUITY - USD ($) $ in Thousands	Common stock	Additional paid in capital	Accumulated foreign currency translation adjustments	Accumulated unrealized gains (losses) on available-for-sale debt securities	Accumulated deficit	Total
Increase (Decrease) in Stockholders' Equity
Cumulative effect of applying new accounting standards					$ 8,645	$ 8,645
Beginning balance as adjusted	$ 854	$ 455,401	$ (17,867)	$ (3,774)	(222,985)	211,629
Beginning balance as adjusted, shares	562,119,334
Balance at the beginning of the period at Dec. 31, 2017	$ 854	455,401	(17,867)	(3,774)	(231,630)	202,984
Balance at the beginning of the period, shares at Dec. 31, 2017	562,119,334
Increase (Decrease) in Stockholders' Equity
Net loss					(20,738)	(20,738)
Issuance of shares upon exercise of stock options	$ 4	1,530				1,534
Issuance of shares upon exercise of stock options (in shares)	2,740,626
Foreign currency translation adjustments			(2,525)			(2,525)
Unrealized holding gains (losses) on available-for-sale debt securities, net of tax of $0				(4,056)		(4,056)
Reclassification from accumulated other comprehensive income of gains on available-for-sale debt securities included in net income, net of tax of $				1,163		1,163
Share-based compensation expense		4,672				4,672
Balance at the end of the period at Mar. 31, 2018	$ 858	461,603	(20,392)	(6,667)	(243,723)	191,679
Balance at the end of the period, shares at Mar. 31, 2018	564,859,960
Balance at the beginning of the period at Dec. 31, 2017	$ 854	455,401	(17,867)	(3,774)	(231,630)	202,984
Balance at the beginning of the period, shares at Dec. 31, 2017	562,119,334
Increase (Decrease) in Stockholders' Equity
Net loss						(64,583)
Unrealized holding gains (losses) on available-for-sale debt securities, net of tax of $0						1,167
Balance at the end of the period at Jun. 30, 2018	$ 860	466,229	(14,285)	(134)	(287,568)	165,102
Balance at the end of the period, shares at Jun. 30, 2018	566,496,400
Balance at the beginning of the period at Mar. 31, 2018	$ 858	461,603	(20,392)	(6,667)	(243,723)	191,679
Balance at the beginning of the period, shares at Mar. 31, 2018	564,859,960
Increase (Decrease) in Stockholders' Equity
Net loss					(43,845)	(43,845)
Issuance of shares upon exercise of stock options	$ 2	887				889
Issuance of shares upon exercise of stock options (in shares)	1,636,440
Foreign currency translation adjustments			6,107			6,107
Unrealized holding gains (losses) on available-for-sale debt securities, net of tax of $0				5,223		5,223
Reclassification from accumulated other comprehensive income of gains on available-for-sale debt securities included in net income, net of tax of $				1,310		1,310
Share-based compensation expense		3,739				3,739
Balance at the end of the period at Jun. 30, 2018	$ 860	466,229	(14,285)	(134)	(287,568)	165,102
Balance at the end of the period, shares at Jun. 30, 2018	566,496,400
Balance at the beginning of the period at Dec. 31, 2018	$ 939	574,208	(9,607)	(156)	(318,499)	$ 246,885
Balance at the beginning of the period, shares at Dec. 31, 2018	627,454,270					627,454,270
Increase (Decrease) in Stockholders' Equity
Net loss					(27,412)	$ (27,412)
Issuance of shares upon exercise of stock options	$ 1	35				36
Issuance of shares upon exercise of stock options (in shares)	840,432
Foreign currency translation adjustments			(3,543)			(3,543)
Unrealized holding gains (losses) on available-for-sale debt securities, net of tax of $0				210		210
Share-based compensation expense		3,479				3,479
Balance at the end of the period at Mar. 31, 2019	$ 940	577,722	(13,150)	54	(345,911)	219,655
Balance at the end of the period, shares at Mar. 31, 2019	628,294,702
Balance at the beginning of the period at Dec. 31, 2018	$ 939	574,208	(9,607)	(156)	(318,499)	$ 246,885
Balance at the beginning of the period, shares at Dec. 31, 2018	627,454,270					627,454,270
Increase (Decrease) in Stockholders' Equity
Net loss						$ (68,499)
Unrealized holding gains (losses) on available-for-sale debt securities, net of tax of $0						278
Balance at the end of the period at Jun. 30, 2019	$ 943	581,245	(8,308)	109	(386,998)	$ 186,991
Balance at the end of the period, shares at Jun. 30, 2019	630,672,578					630,672,578
Balance at the beginning of the period at Mar. 31, 2019	$ 940	577,722	(13,150)	54	(345,911)	$ 219,655
Balance at the beginning of the period, shares at Mar. 31, 2019	628,294,702
Increase (Decrease) in Stockholders' Equity
Net loss					(41,087)	(41,087)
Issuance of shares upon exercise of stock options	$ 3	327				330
Issuance of shares upon exercise of stock options (in shares)	2,377,876
Foreign currency translation adjustments			4,842			4,842
Unrealized holding gains (losses) on available-for-sale debt securities, net of tax of $0				68		68
Reclassification from accumulated other comprehensive income of gains on available-for-sale debt securities included in net income, net of tax of $				(13)		(13)
Share-based compensation expense		3,196				3,196
Balance at the end of the period at Jun. 30, 2019	$ 943	$ 581,245	$ (8,308)	$ 109	$ (386,998)	$ 186,991
Balance at the end of the period, shares at Jun. 30, 2019	630,672,578					630,672,578

UNAUDITED CONDENSED CONSOLIDA_7

UNAUDITED CONDENSED CONSOLIDATED STATEMENT OF CHANGE IN EQUITY (PARENTHETICAL) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other comprehensive income (loss), available-for-sale securities, before reclassification adjustments, tax
Unrealized holding gains on available-for-sale debt securities, tax	$ 0	$ 0	$ 0	$ 0
Reclassification from accumulated other comprehensive income of gains on available-for-sale debt securities included in net income, tax	$ 0	$ 0	$ 0	$ 0

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities
Net loss	$ (68,499,000)	$ (64,583,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	3,642,000	3,499,000
Amortization	333,000	304,000
Share-based compensation expense	6,675,000	8,411,000
Realized loss on available-for-sale debt securities		2,473,000
Realized (gain) loss on available-for-sale debt securities	(13,000)
Unrealized foreign exchange losses	1,048,000	2,915,000
Other	(153,000)	16,000
Changes in operating assets and liabilities:
Increase in receivables and other operating assets	(16,851,000)	(11,602,000)
Decrease in non-current operating assets	1,263,000	87,000
Increase (decrease) in payables and deferred revenue	2,184,000	(24,162,000)
Net cash used in operating activities	(70,371,000)	(82,642,000)
Cash flows from investing activities
Acquisition of property, plant and equipment	(1,202,000)	(3,139,000)
Acquisition of intangibles	(922,000)	(10,000)
Maturity or redemption of marketable securities	54,324,000	70,717,000
Investment in marketable securities	(15,983,000)	(33,556,000)
Net cash provided by investing activities	36,217,000	34,012,000
Cash flows from financing activities
Proceeds from exercise of stock options	366,000	2,424,000
Net cash provided by financing activities	366,000	2,424,000
Effect of currency exchange rate changes on cash, cash equivalents and restricted cash	289,000	4,417,000
Net decrease in cash and cash equivalents	(33,499,000)	(41,789,000)
Cash, cash equivalents and restricted cash at start of period	72,476,000	88,296,000
Cash, cash equivalents and restricted cash at end of period	$ 38,977,000	$ 46,507,000

General

General	6 Months Ended
	Jun. 30, 2019
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 patients, particularly for the treatment of solid tumors. The Company’s proprietary SPEAR (Specific Peptide Enhanced Affinity Receptor) T-cell platform enables it to identify cancer targets, find and genetically engineer T-cell receptors (“TCRs”), and produce therapeutic candidates (“SPEAR T-cells”) for administration to patients. Using its affinity engineered TCRs, the Company aims to become the first company to have a TCR T-cell approved for the treatment of a solid tumor indication. 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 SPEAR T-cells, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of the Company’s SPEAR T-cells, the need to develop a suitable commercial manufacturing process and protection of proprietary technology. If the Company does not successfully commercialize any of its SPEAR T-cells, it will be unable to generate product revenue or achieve profitability. The Company had an accumulated deficit of $387.0 million as of June 30, 2019.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2019
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 2 — Summary of Significant Accounting Policies (a) Basis of presentation The condensed consolidated interim 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 interim 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 February 27, 2019 (the “Annual Report”). The balance sheet as of December 31, 2018 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. On January 1, 2019, the Company adopted new guidance on the accounting for leases, which has been codified within Accounting Standard Codification Topic 842, Leases (“ASC 842”). The Company has adopted the guidance using the modified retrospective approach, with the cumulative effect of initially applying the guidance recognized as an adjustment to the opening balance of equity at January 1, 2019. Therefore, the comparative financial information for the three and six months ended June 30, 2018 and as of December 31, 2018 has not been restated and continues to be reported under previous guidance. The effect of adopting ASC 842 on the accumulated deficit, total stockholders’ equity and net assets as at January 1, 2019 was $0. (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 consolidated financial statements and reported amounts of revenues and expenses during the reporting period. Estimates and assumptions are primarily made in relation to the valuation of share options, valuation allowances relating to deferred tax assets, revenue recognition, estimating clinical trial expenses and estimating reimbursements from R&D tax and expenditure credits. 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 8, Fair value measurements. (d) Leases On January 1, 2019, the Company adopted a new standard, Accounting Standard Update 2016-02 – Leases, which is codified in ASC 842. The comparative financial information for the three and six months ended June 30, 2018 and as of December 31, 2018 has not been restated and is prepared in accordance with the accounting policies that are described in Note 2 to the consolidated financial statements included in the Annual Report. ​ The Company determines whether an arrangement is a lease at contract inception by establishing if the contract conveys the right to use, or control the use of, identified property, plant, or equipment for a period of time in exchange for consideration. Leases may be classified as finance leases or operating leases. All the Company’s leases are classified as operating leases as they were previously classed as these and the lease classification is not reassessed on adoption of ASC 842. Operating lease right-of-use (ROU) assets and operating lease liabilities recognized in the Condensed Consolidated Balance Sheet represent the right to use an underlying asset for the lease term and an obligation to make lease payments arising from the lease respectively. ​ Operating lease ROU assets and operating lease liabilities are recognized at the lease commencement date based on the present value of minimum lease payments over the lease term. Since the rate implicit in the lease is not readily determinable, the Company uses its incremental borrowing rates (the rate of interest that the Company would have to pay to borrow on a collateralized basis over a similar term for an amount equal to the lease payments in a similar economic environment) based on the information available at commencement date in determining the discount rate used to calculate the present value of lease payments. As the Company has no external borrowings, the incremental borrowing rates are determined using information on indicative borrowing rates that would be available to the Company based on the value, currency and borrowing term provided by financial institutions, adjusted for company and market specific factors. The lease term is based on the non-cancellable period in the lease contract, and options to extend the lease are included when it is reasonably certain that the Company will exercise that option. Any termination fees are included in the calculation of the ROU asset and lease liability when it is assumed that the lease will be terminated. ​ The Company accounts for lease components (e.g. fixed payments including rent and termination costs) separately from non-lease components (e.g. common-area maintenance costs and service charges based on utilization) which are recognized over the period in which the obligation occurs. ​ At each reporting date, the operating lease liabilities are increased by interest and reduced by repayments made under the lease agreements. The right-of-use asset is subsequently measured for an operating lease at the amount of the remeasured lease liability (i.e. the present value of the remaining lease payments), adjusted for the remaining balance of any lease incentives received, any cumulative prepaid or accrued rent if the lease payments are uneven throughout the lease term, and any unamortized initial direct costs. The Company has operating leases in relation to property for office and research facilities. All of the leases have termination options, and it is assumed that the initial termination options for the buildings will be activated for most of these. The maximum lease term without activation of termination options is to 2041. ​ The Company has elected not to recognize a right-of-use asset and lease liability for short-term leases. A short-term lease is a lease with a lease term of 12 months or less and which does not include an option to purchase the underlying asset that the lessee is reasonably certain to exercise. ​ Operating lease costs are recognized on a straight line basis over the lease term, and they are categorized within Research and development and General and administrative expenses in the Condensed Consolidated Statement of Operations. The operating lease cash flows are categorized under Net cash used in operating activities in the Condensed Consolidated Statement of Cash Flows. ​ (e ) New accounting pronouncements Adopted in the period Leases On January 1, 2019, the Company adopted ​ The adoption of ASC 842 has had a material impact on the Company’s financial statements. At January 1, 2019 the Company recognized right-of-use assets and liabilities for operating leases following the adoption date of $22.2 million and $26.9 million respectively and derecognized $4.7 million of other liabilities and prepayments that had been recognized under previous guidance. During the three months ended June 30, 2019, management performed further benchmarking of the incremental borrowing rate used in the determination of the right-of-use asset and the lease liability as more information became publicly available. This has highlighted that the Company is at the lower end of the range for comparable companies and as a result, management performed further analysis of the factors which were considered. Based on this additional analysis, the incremental borrowing rate has increased from a weighted-average of 4.65% to 7.2%. The change in the incremental borrowing rate has reduced the right-of-use asset and corresponding lease liability by $2.6 million. There is no impact on the Condensed Consolidated Statement of Operations and Condensed Consolidated Statement of Cash Flows. ​ ​ To be adopted in future periods 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 guidance is effective for the fiscal year beginning January 1, 2020, including interim periods within that fiscal year. Early application is permitted for the fiscal year beginning January 1, 2019, including interim periods within that fiscal year. 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. The Company is currently evaluating the impact of the guidance on its consolidated financial statements. Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In August 2018, the FASB issued ASU 2018-15 – Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40) Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). The guidance is effective for the fiscal year beginning January 1, 2020, including interim periods within that fiscal year. Early application is permitted for the fiscal year beginning January 1, 2019, including interim periods within that fiscal year. The guidance may be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. The Company is currently evaluating the impact of the guidance on its consolidated financial statements. Changes to the Disclosure Requirements for Fair Value Measurement In August 2018, the FASB issued ASU 2018-13 – Fair Value Measurement (Topic 820) - Disclosure Framework— Changes to the Disclosure Requirements for Fair Value Measurement, which modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement. The guidance is effective for the fiscal year beginning January 1, 2020, including interim periods within that fiscal year. Early application is permitted. Certain amendments apply prospectively with the all other amendments applied retrospectively to all periods presented upon their effective date. The Company is currently evaluating the impact of the guidance on its consolidated financial statements. ​ ​ ​

Revenue

Revenue	6 Months Ended
	Jun. 30, 2019
Revenue
Revenue	Note 3 — Revenue Revenue from contracts with customers arises from one customer, which is GlaxoSmithKline (“GSK”), in one geographic location, which is the United Kingdom. Revenue comprises the following categories (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Three months ended Six months ended ​ Six months ended ​ June 30, ​ June 30, ​ June 30, ​ June 30, ​ 2019 2018 ​ 2019 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Development $ 157 $ 9,038 ​ $ 157 $ 17,234 ​ $ 157 $ 9,038 ​ $ 157 $ 17,234 ​ The Company has one contract with a customer, which is the GSK Collaboration and License Agreement. The GSK Collaboration and License Agreement consists of multiple performance obligations. In 2019, GSK nominated a third target under the Collaboration and License Agreement. Development of this target commenced during the three months ended June 30, 2019. The amount of the transaction price probable of being received that is allocated to performance obligations that are unsatisfied or partially satisfied at June 30, 2019 was $3.0 million. The revenue allocated to the third target program will be recognized over an estimated period of 18 months as the development of the target progresses. The Company became entitled to invoice GSK $3.2 million upon the nomination of the third target. Under the terms of the GSK Collaboration and License Agreement, the Company may also be entitled to development and regulatory milestones. The development and regulatory milestones are per product milestones and are dependent on achievement of certain obligations, the nature of the product being developed, stage of development of product, territory in which an obligation is achieved and type of indication or indications in relation to which the product is being developed. In addition, for any program multiple products may be developed to address different HLA-types. These amounts have not been included within the transaction price as of June 30, 2019 because they are not considered probable. ​ The Company may also receive commercialization milestones upon the first commercial sale of a product based on the indication and the territory and mid-single to low double-digit royalties on worldwide net sales. These amounts have not been included within the transaction price as of June 30, 2019 because they are sales or usage-based royalties promised in exchange for a license of intellectual property, which will be recognized when the subsequent sale or usage occurs. Development revenue recognized in the three and six months ended June 30, 2018 related to development of the second target program, PRAME, which ended in 2018, and the NY-ESO program, which was transferred to GSK on July 23, 2018. ​ The following table shows movements in deferred revenue for the six months ended June 30, 2019 (in thousands): ​ ​ ​ ​ ​ ​ Deferred revenue Deferred revenue at January 1, 2019 $ — Revenue in the period ​ (157) Amounts invoiced in the period ​ ​ 3,217 Foreign exchange arising on consolidation ​ ​ (44) Deferred revenue at June 30, 2019 ​ $ 3,016 ​

Operating Leases

Operating Leases	6 Months Ended
	Jun. 30, 2019
Operating leases
Operating leases	Note 4 – Operating leases The following table shows the lease costs for the three and six months ended June 30, 2019 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ ​ 2019 2019 Lease cost: ​ ​ ​ ​ ​ ​ Operating lease cost ​ $ 1,024 $ 2,014 Short-term lease cost ​ 121 ​ 168 ​ ​ $ 1,145 $ 2,182 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six months ended ​ ​ ​ ​ ​ June 30, ​ ​ ​ ​ ​ 2019 Other information: ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases (in thousands) ​ ​ ​ ​ $ 2,194 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ Weighted-average remaining lease term - operating leases ​ ​ ​ ​ years Weighted-average discount rate - operating leases ​ ​ ​ ​ 7.2% ​ The maturities of operating lease liabilities are as follows (in thousands): ​ ​ ​ ​ ​ ​ Operating leases ​ ​ ​ ​ 2019 $ 2,037 2020 ​ 4,110 ​ 2021 ​ 4,153 ​ 2022 ​ 4,158 ​ 2023 ​ 3,918 ​ after 2023 ​ 16,302 ​ Total lease payments ​ ​ 34,678 ​ Less: Imputed interest ​ ​ (8,674) ​ Present value of lease liability ​ $ 26,004 ​ ​ The Company has operating leases in relation to property for office and research facilities. The maximum lease term without activation of termination options is to 2041. ​

Other expense, net

Other expense, net	6 Months Ended
	Jun. 30, 2019
Other expense, net
Other income, net	Note 5 — Other expense, net Other expense, net consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign exchange losses $ (6,403) $ (14,022) $ (1,013) $ (5,605) Gains (losses) on redemption or maturity of available-for-sale debt securities ​ 13 ​ (1,310) ​ 13 ​ (2,473) Other ​ 113 ​ (74) ​ 153 ​ (198) ​ $ (6,277) $ (15,406) $ (847) $ (8,276) ​

Loss per share

Loss per share	6 Months Ended
	Jun. 30, 2019
Loss per share
Loss per share	Note 6 — Loss per share ​ The dilutive effect of 97,292,240 and 87,434,329 stock options outstanding as of June 30, 2019 and 2018, respectively, have been excluded from the diluted loss per share calculation, because they would have an antidilutive effect on the loss per share for the period.

Accumulated other comprehensive

Accumulated other comprehensive income (loss)	6 Months Ended
	Jun. 30, 2019
Accumulated other comprehensive income (loss)
Accumulated other comprehensive income (loss)	Note 7 — Accumulated other comprehensive income (loss) The following amounts were reclassified out of other comprehensive income during the three and six months ended June 30, 2019 and 2018 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount reclassified ​ ​ ​ Amount reclassified ​ ​ Three months ended ​ Three months ended ​ ​ ​ ​ Six months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ ​ ​ ​ June 30, ​ June 30, Component of accumulated other comprehensive income ​ 2019 ​ 2018 ​ ​ ​ 2019 ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized gains (losses) on available-for-sale securities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reclassification adjustment for (gains) losses on available-for-sale debt securities $ (13) ​ $ 1,310 ​ ​ ​ ​ $ (13) ​ $ 2,473 ​ The affected line in the Condensed Consolidated Statement of Operations for the amounts reclassified out of other comprehensive income above is “Other expense, net”. ​ ​

Fair value measurements

Fair value measurements	6 Months Ended
	Jun. 30, 2019
Fair value measurements
Fair value measurements	Note 8 — 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 June 30, 2019 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value measurements using ​ ​ June 30, ​ Level 1 ​ Level 2 ​ Level 3 ​ 2019 ​ ​ ​ ​ ​ ​ Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate debt securities $ 91,831 $ 91,831 $ — $ — Agency bond ​ ​ 3,999 ​ ​ — ​ ​ 3,999 ​ ​ — Certificate of deposit ​ ​ 3,002 ​ — ​ 3,002 ​ — ​ $ 98,832 $ 91,831 $ 7,001 $ — ​ 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.

Available-for-sale debt securit

Available-for-sale debt securities	6 Months Ended
	Jun. 30, 2019
Available-for-sale debt securities
Available-for-sale debt securities	Note 9 — Available-for-sale debt securities As of June 30, 2019, the Company has the following investments in available-for-sale debt securities (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ Aggregate ​ ​ Remaining ​ Amortized ​ Unrealized ​ Unrealized ​ Estimated ​ Contractual Maturity Cost Gains Losses Fair Value Cash equivalents: ​ ​ ​ ​ Money market funds Less than 3 months ​ $ 10,241 ​ $ — ​ $ — ​ $ 10,241 ​ ​ $ 10,241 ​ $ — ​ $ — ​ $ 10,241 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Marketable securities: ​ ​ ​ ​ Corporate debt securities Less than 3 months ​ $ 35,703 ​ $ 18 ​ $ — ​ $ 35,721 Corporate debt securities ​ 3 months to 1 year ​ ​ 56,027 ​ ​ 85 ​ ​ (2) ​ ​ 56,110 Agency bond ​ 3 months to 1 year ​ ​ 3,992 ​ ​ 7 ​ ​ — ​ ​ 3,999 Certificate of deposit ​ Less than 3 months ​ ​ 3,002 ​ ​ — ​ ​ — ​ ​ 3,002 ​ ​ $ 98,724 ​ $ 110 ​ $ (2) ​ $ 98,832 ​ Maturity information above is categorized by the period remaining after the reporting period until the maturity date. In the three and six months ended June 30, 2019, $13,000 of realized gains recognized on the maturity of available-for-sale debt securities were reclassified out of other accumulated other comprehensive loss. As of June 30, 2019 and December 31, 2018, the aggregate fair value of securities held by the Company in an unrealized loss position was $9.6 million and $117.2 million respectively, which consisted of 3 and 37 separate securities, respectively. No securities have been in an unrealized loss position for more than one year. As of June 30, 2019, the securities in an unrealized loss position are not considered to be other than temporarily impaired because the impairments are not severe, have been for a short duration and are due to normal market fluctuations. Furthermore, the Company does not intend to sell the debt securities in an unrealized loss position and it is unlikely that the Company will be required to sell these securities before the recovery of the amortized cost.

Other current assets

Other current assets	6 Months Ended
	Jun. 30, 2019
Other current assets
Other current assets	Note 10 — Other current assets Other current assets consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ December 31, ​ 2019 2018 Corporate tax receivable $ 26,328 $ 16,459 Prepayments ​ 8,600 ​ 6,279 Clinical materials ​ 1,755 ​ 1,087 VAT receivable ​ ​ 636 ​ ​ 1,505 Other current assets ​ 599 ​ 439 ​ ​ $ 37,918 ​ $ 25,769 ​

Accrued expenses and other curr

Accrued expenses and other current liabilities	6 Months Ended
	Jun. 30, 2019
Accrued expenses and other current liabilities
Accrued expenses and other current liabilities	Note 11 — Accrued expenses and other current liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ December 31, ​ 2019 2018 Accrued clinical & development expenditure ​ $ 9,769 ​ $ 9,637 Accrued employee expenses ​ ​ 5,678 ​ ​ 7,553 Other accrued expenditure ​ ​ 2,739 ​ ​ 2,422 Other ​ 409 ​ 742 ​ ​ $ 18,595 ​ $ 20,354 ​

Share-based compensation

Share-based compensation	6 Months Ended
	Jun. 30, 2019
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 ​ Six months ended ​ ​ ​ ​ June 30, ​ June 30, ​ ​ 2019 2018 2019 2018 ​ ​ Research and development ​ $ 786 ​ $ 2,071 ​ $ 2,807 ​ $ 4,285 ​ ​ General and administrative ​ 2,410 ​ 2,008 ​ 3,868 ​ ​ 4,126 ​ ​ ​ ​ $ 3,196 ​ $ 4,079 ​ $ 6,675 ​ $ 8,411 ​ ​ ​ 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 ​ Six months ended ​ ​ ​ June 30, ​ June 30, ​ ​ 2019 2018 2019 2018 ​ Number of options over ordinary shares granted ​ ​ 936,696 ​ ​ 1,435,685 ​ ​ 11,743,896 ​ ​ 11,430,341 ​ Weighted average fair value of ordinary shares options ​ $ 0.39 ​ $ 1.18 ​ $ 0.54 ​ $ 0.80 ​ Number of additional options with a nominal exercise price granted ​ ​ 459,240 ​ ​ 151,056 ​ ​ 6,957,366 ​ ​ 6,703,692 ​ Weighted average fair value of options with a nominal exercise price ​ $ 0.70 ​ ​ 1.88 ​ $ 0.93 ​ $ 1.35 ​ ​

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2019
Summary of Significant Accounting Policies
Basis of presentation	(a) Basis of presentation The condensed consolidated interim 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 interim 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 February 27, 2019 (the “Annual Report”). The balance sheet as of December 31, 2018 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. On January 1, 2019, the Company adopted new guidance on the accounting for leases, which has been codified within Accounting Standard Codification Topic 842, Leases (“ASC 842”). The Company has adopted the guidance using the modified retrospective approach, with the cumulative effect of initially applying the guidance recognized as an adjustment to the opening balance of equity at January 1, 2019. Therefore, the comparative financial information for the three and six months ended June 30, 2018 and as of December 31, 2018 has not been restated and continues to be reported under previous guidance. The effect of adopting ASC 842 on the accumulated deficit, total stockholders’ equity and net assets as at January 1, 2019 was $0.
Use of estimates in 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 consolidated financial statements and reported amounts of revenues and expenses during the reporting period. Estimates and assumptions are primarily made in relation to the valuation of share options, valuation allowances relating to deferred tax assets, revenue recognition, estimating clinical trial expenses and estimating reimbursements from R&D tax and expenditure credits. 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 8, Fair value measurements.
Fair value measurements	(c) Fair value measurements
Leases	(d) Leases
New accounting pronouncements	(e ) New accounting pronouncements Adopted in the period Leases On January 1, 2019, the Company adopted ​ The adoption of ASC 842 has had a material impact on the Company’s financial statements. At January 1, 2019 the Company recognized right-of-use assets and liabilities for operating leases following the adoption date of $22.2 million and $26.9 million respectively and derecognized $4.7 million of other liabilities and prepayments that had been recognized under previous guidance.
Correction of an immaterial error to the incremental borrowing rate	During the three months ended June 30, 2019, management performed further benchmarking of the incremental borrowing rate used in the determination of the right-of-use asset and the lease liability as more information became publicly available. This has highlighted that the Company is at the lower end of the range for comparable companies and as a result, management performed further analysis of the factors which were considered. Based on this additional analysis, the incremental borrowing rate has increased from a weighted-average of 4.65% to 7.2%. The change in the incremental borrowing rate has reduced the right-of-use asset and corresponding lease liability by $2.6 million. There is no impact on the Condensed Consolidated Statement of Operations and Condensed Consolidated Statement of Cash Flows. ​ ​ To be adopted in future periods 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 guidance is effective for the fiscal year beginning January 1, 2020, including interim periods within that fiscal year. Early application is permitted for the fiscal year beginning January 1, 2019, including interim periods within that fiscal year. 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. The Company is currently evaluating the impact of the guidance on its consolidated financial statements. Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In August 2018, the FASB issued ASU 2018-15 – Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40) Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). The guidance is effective for the fiscal year beginning January 1, 2020, including interim periods within that fiscal year. Early application is permitted for the fiscal year beginning January 1, 2019, including interim periods within that fiscal year. The guidance may be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. The Company is currently evaluating the impact of the guidance on its consolidated financial statements. Changes to the Disclosure Requirements for Fair Value Measurement In August 2018, the FASB issued ASU 2018-13 – Fair Value Measurement (Topic 820) - Disclosure Framework— Changes to the Disclosure Requirements for Fair Value Measurement, which modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement. The guidance is effective for the fiscal year beginning January 1, 2020, including interim periods within that fiscal year. Early application is permitted. Certain amendments apply prospectively with the all other amendments applied retrospectively to all periods presented upon their effective date. The Company is currently evaluating the impact of the guidance on its consolidated financial statements. ​

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2019
Summary of Significant Accounting Policies
Schedule of maturities of operating lease liabilities	The maturities of operating lease liabilities are as follows (in thousands): ​ ​ ​ ​ ​ ​ Operating leases ​ ​ ​ ​ 2019 $ 2,037 2020 ​ 4,110 ​ 2021 ​ 4,153 ​ 2022 ​ 4,158 ​ 2023 ​ 3,918 ​ after 2023 ​ 16,302 ​ Total lease payments ​ ​ 34,678 ​ Less: Imputed interest ​ ​ (8,674) ​ Present value of lease liability ​ $ 26,004 ​ ​ The Company has operating leases in relation to property for office and research facilities. The maximum lease term without activation of termination options is to 2041. ​
Schedule of amounts reclassified out of other comprehensive income	The following amounts were reclassified out of other comprehensive income during the three and six months ended June 30, 2019 and 2018 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount reclassified ​ ​ ​ Amount reclassified ​ ​ Three months ended ​ Three months ended ​ ​ ​ ​ Six months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ ​ ​ ​ June 30, ​ June 30, Component of accumulated other comprehensive income ​ 2019 ​ 2018 ​ ​ ​ 2019 ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized gains (losses) on available-for-sale securities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reclassification adjustment for (gains) losses on available-for-sale debt securities $ (13) ​ $ 1,310 ​ ​ ​ ​ $ (13) ​ $ 2,473

Revenue (Tables)

Revenue (Tables)	6 Months Ended
	Jun. 30, 2019
Revenue
Schedule of movements in deferred revenue	The following table shows movements in deferred revenue for the six months ended June 30, 2019 (in thousands): ​ ​ ​ ​ ​ ​ Deferred revenue Deferred revenue at January 1, 2019 $ — Revenue in the period ​ (157) Amounts invoiced in the period ​ ​ 3,217 Foreign exchange arising on consolidation ​ ​ (44) Deferred revenue at June 30, 2019 ​ $ 3,016 ​

Operating Leases (Tables)

Operating Leases (Tables)	6 Months Ended
	Jun. 30, 2019
Operating leases
Schedule of lease cost	The following table shows the lease costs for the three and six months ended June 30, 2019 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ ​ 2019 2019 Lease cost: ​ ​ ​ ​ ​ ​ Operating lease cost ​ $ 1,024 $ 2,014 Short-term lease cost ​ 121 ​ 168 ​ ​ $ 1,145 $ 2,182 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six months ended ​ ​ ​ ​ ​ June 30, ​ ​ ​ ​ ​ 2019 Other information: ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases (in thousands) ​ ​ ​ ​ $ 2,194 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ Weighted-average remaining lease term - operating leases ​ ​ ​ ​ years Weighted-average discount rate - operating leases ​ ​ ​ ​ 7.2%
Schedule of maturities of operating lease liabilities	The maturities of operating lease liabilities are as follows (in thousands): ​ ​ ​ ​ ​ ​ Operating leases ​ ​ ​ ​ 2019 $ 2,037 2020 ​ 4,110 ​ 2021 ​ 4,153 ​ 2022 ​ 4,158 ​ 2023 ​ 3,918 ​ after 2023 ​ 16,302 ​ Total lease payments ​ ​ 34,678 ​ Less: Imputed interest ​ ​ (8,674) ​ Present value of lease liability ​ $ 26,004 ​ ​ The Company has operating leases in relation to property for office and research facilities. The maximum lease term without activation of termination options is to 2041. ​

Other expense, net (Tables)

Other expense, net (Tables)	6 Months Ended
	Jun. 30, 2019
Other expense, net
Schedule of other expense, net	Other expense, net consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ 2019 2018 2019 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign exchange losses $ (6,403) $ (14,022) $ (1,013) $ (5,605) Gains (losses) on redemption or maturity of available-for-sale debt securities ​ 13 ​ (1,310) ​ 13 ​ (2,473) Other ​ 113 ​ (74) ​ 153 ​ (198) ​ $ (6,277) $ (15,406) $ (847) $ (8,276) ​

Accumulated other comprehensi_2

Accumulated other comprehensive income (loss) (Tables)	6 Months Ended
	Jun. 30, 2019
Accumulated other comprehensive income (loss)
Schedule of amounts reclassified out of other comprehensive income	The following amounts were reclassified out of other comprehensive income during the three and six months ended June 30, 2019 and 2018 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount reclassified ​ ​ ​ Amount reclassified ​ ​ Three months ended ​ Three months ended ​ ​ ​ ​ Six months ended ​ Six months ended ​ ​ June 30, ​ June 30, ​ ​ ​ ​ June 30, ​ June 30, Component of accumulated other comprehensive income ​ 2019 ​ 2018 ​ ​ ​ 2019 ​ 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized gains (losses) on available-for-sale securities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reclassification adjustment for (gains) losses on available-for-sale debt securities $ (13) ​ $ 1,310 ​ ​ ​ ​ $ (13) ​ $ 2,473

Fair value measurements (Tables

Fair value measurements (Tables)	6 Months Ended
	Jun. 30, 2019
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 June 30, 2019 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value measurements using ​ ​ June 30, ​ Level 1 ​ Level 2 ​ Level 3 ​ 2019 ​ ​ ​ ​ ​ ​ Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate debt securities $ 91,831 $ 91,831 $ — $ — Agency bond ​ ​ 3,999 ​ ​ — ​ ​ 3,999 ​ ​ — Certificate of deposit ​ ​ 3,002 ​ — ​ 3,002 ​ — ​ $ 98,832 $ 91,831 $ 7,001 $ —

Available-for-sale debt secur_2

Available-for-sale debt securities (Tables)	6 Months Ended
	Jun. 30, 2019
Available-for-sale debt securities
Schedule of investments in available-for-sale debt securities	As of June 30, 2019, the Company has the following investments in available-for-sale debt securities (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ Aggregate ​ ​ Remaining ​ Amortized ​ Unrealized ​ Unrealized ​ Estimated ​ Contractual Maturity Cost Gains Losses Fair Value Cash equivalents: ​ ​ ​ ​ Money market funds Less than 3 months ​ $ 10,241 ​ $ — ​ $ — ​ $ 10,241 ​ ​ $ 10,241 ​ $ — ​ $ — ​ $ 10,241 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Marketable securities: ​ ​ ​ ​ Corporate debt securities Less than 3 months ​ $ 35,703 ​ $ 18 ​ $ — ​ $ 35,721 Corporate debt securities ​ 3 months to 1 year ​ ​ 56,027 ​ ​ 85 ​ ​ (2) ​ ​ 56,110 Agency bond ​ 3 months to 1 year ​ ​ 3,992 ​ ​ 7 ​ ​ — ​ ​ 3,999 Certificate of deposit ​ Less than 3 months ​ ​ 3,002 ​ ​ — ​ ​ — ​ ​ 3,002 ​ ​ $ 98,724 ​ $ 110 ​ $ (2) ​ $ 98,832

Other current assets (Tables)

Other current assets (Tables)	6 Months Ended
	Jun. 30, 2019
Other current assets
Summary of other current assets	Other current assets consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ December 31, ​ 2019 2018 Corporate tax receivable $ 26,328 $ 16,459 Prepayments ​ 8,600 ​ 6,279 Clinical materials ​ 1,755 ​ 1,087 VAT receivable ​ ​ 636 ​ ​ 1,505 Other current assets ​ 599 ​ 439 ​ ​ $ 37,918 ​ $ 25,769 ​

Accrued expenses and other cu_2

Accrued expenses and other current liabilities (Tables)	6 Months Ended
	Jun. 30, 2019
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): ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, ​ December 31, ​ 2019 2018 Accrued clinical & development expenditure ​ $ 9,769 ​ $ 9,637 Accrued employee expenses ​ ​ 5,678 ​ ​ 7,553 Other accrued expenditure ​ ​ 2,739 ​ ​ 2,422 Other ​ 409 ​ 742 ​ ​ $ 18,595 ​ $ 20,354 ​

Share-based compensation (Table

Share-based compensation (Tables)	6 Months Ended
	Jun. 30, 2019
Share-based compensation
Summary of share-based compensation expense included in the unaudited 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 ​ Six months ended ​ ​ ​ ​ June 30, ​ June 30, ​ ​ 2019 2018 2019 2018 ​ ​ Research and development ​ $ 786 ​ $ 2,071 ​ $ 2,807 ​ $ 4,285 ​ ​ General and administrative ​ 2,410 ​ 2,008 ​ 3,868 ​ ​ 4,126 ​ ​ ​ ​ $ 3,196 ​ $ 4,079 ​ $ 6,675 ​ $ 8,411 ​ ​
Summary of share options and options which have a nominal exercise price	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 ​ Six months ended ​ ​ ​ June 30, ​ June 30, ​ ​ 2019 2018 2019 2018 ​ Number of options over ordinary shares granted ​ ​ 936,696 ​ ​ 1,435,685 ​ ​ 11,743,896 ​ ​ 11,430,341 ​ Weighted average fair value of ordinary shares options ​ $ 0.39 ​ $ 1.18 ​ $ 0.54 ​ $ 0.80 ​ Number of additional options with a nominal exercise price granted ​ ​ 459,240 ​ ​ 151,056 ​ ​ 6,957,366 ​ ​ 6,703,692 ​ Weighted average fair value of options with a nominal exercise price ​ $ 0.70 ​ ​ 1.88 ​ $ 0.93 ​ $ 1.35 ​ ​

General (Details)

General (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
General
Accumulated deficit	$ 386,998	$ 318,499

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Basis of Presentation (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Dec. 31, 2017
Summary of Significant Accounting Policies
Cumulative effect of applying new accounting standards	$ 0	$ 8,645

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Leases - General Information (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Jun. 30, 2019	Dec. 31, 2017
Cumulative effect of applying new accounting standards	$ 0		$ 8,645
Operating lease right-of-use assets		$ 21,507
Operating lease liability		$ 26,004
ASU 2016-02 | Restatement Adjustment
Operating lease right-of-use assets	22,200
Operating lease liability	26,900
Decrease in other liabilities and prepayments	$ 4,700

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Leases - Cash Flow and cost (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Summary of Significant Accounting Policies
Operating cash flows from operating leases (in thousands)		$ 2,194
Operating lease cost	$ 1,024	2,014
Short-term lease cost	$ 121	$ 168

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Leases - Balance Sheet Information (Details) $ in Thousands	Jun. 30, 2019USD ($)
Summary of Significant Accounting Policies
Operating lease right-of-use assets	$ 21,507
Operating lease liabilities, current	(2,338)
Operating lease liabilities, non-current	$ (23,666)

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Correction of an immaterial error (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019
Summary of Significant Accounting Policies
Weighted average borrowing rate	7.20%	4.65%
Reduction in right-of-use asset	$ 2.6
Reduction in lease liability	$ 2.6

Revenue - Revenue from contract

Revenue - Revenue from contracts with customers (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019USD ($)customer	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)locationcontractcustomer	Jun. 30, 2018USD ($)
Revenue
Revenue, Product and Service [Extensible List]	adap:DevelopmentAndServiceMember	adap:DevelopmentAndServiceMember	adap:DevelopmentAndServiceMember	adap:DevelopmentAndServiceMember
Revenue	$ 157	$ 9,038	$ 157	$ 17,234
Contract assets, liability and receivables
Transaction price			$ 3,000
Revenue recognition period			18 months
Revenue recognized in the period			$ 3,200
Change in contract with customer, liability
Revenue in the period	(157)	(9,038)	(157)	(17,234)
Amounts invoiced in the period			3,217
Foreign exchange arising on consolidation			(44)
Deferred revenue at end of the period	3,016		3,016
Development revenue
Revenue
Revenue	157	9,038	157	17,234
Change in contract with customer, liability
Revenue in the period	$ (157)	$ (9,038)	$ (157)	$ (17,234)
GlaxoSmithKline Intellectual Property Development Ltd
Revenue
Number of customers | customer	1		1
Number of geographic locations | location			1
Number of contracts with customers | contract			1
Contract assets, liability and receivables
Number of customers | customer	1		1

Operating Leases (Details)-Leas

Operating Leases (Details)-Lease Cost $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019USD ($)	Jun. 30, 2019USD ($)
Operating leases
Operating lease cost	$ 1,024	$ 2,014
Short-term lease cost	121	168
Total	$ 1,145	2,182
Operating cash flows from operating leases (in thousands)		$ 2,194
Weighted-average remaining lease term - operating leases	7 years 9 months 18 days	7 years 9 months 18 days
Weighted-average discount rate - operating leases	7.20%	7.20%

Operating Leases (Details)-Matu

Operating Leases (Details)-Maturities $ in Thousands	Jun. 30, 2019USD ($)
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019	$ 2,037
2020	4,110
2021	4,153
2022	4,158
2023	3,918
after 2023	16,302
Total lease payments	34,678
Less: Imputed interest	(8,674)
Present value of lease liability	$ 26,004

Other expense, net (Details)

Other expense, net (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other expense, net
Foreign exchange losses	$ (6,403,000)	$ (14,022,000)	$ (1,013,000)	$ (5,605,000)
Gains (losses) on redemption or maturity of available-for-sale debt securities	13,000		13,000
Gains (losses) on redemption or maturity of available-for-sale debt securities		(1,310,000)		(2,473,000)
Other	113,000	(74,000)	153,000	(198,000)
Other income, net	$ (6,277,000)	$ (15,406,000)	$ (847,000)	$ (8,276,000)

Loss per share - Antidilutive s

Loss per share - Antidilutive securities (Details) - shares	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Share options
Antidilutive securities
Potentially dilutive equity instruments excluded from the diluted loss per share (in shares)	97,292,240	87,434,329

Accumulated other comprehensi_3

Accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Accumulated other comprehensive income (loss)
Reclassification adjustment for (gains) losses on available-for-sale debt securities	$ (13)	$ 1,310	$ (13)	$ 2,473

Fair value measurements (Detail

Fair value measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Marketable securities:
Available-for-sale securities, Debt Securities, Current, Total	$ 98,832	$ 136,755
Recurring basis
Marketable securities:
Corporate debt securities	91,831
Agency bond	3,999
Certificate of deposit	3,002
Available-for-sale securities, Debt Securities, Current, Total	98,832
Recurring basis | Level 1
Marketable securities:
Corporate debt securities	91,831
Available-for-sale securities, Debt Securities, Current, Total	91,831
Recurring basis | Level 2
Marketable securities:
Agency bond	3,999
Certificate of deposit	3,002
Available-for-sale securities, Debt Securities, Current, Total	$ 7,001

Available-for-sale debt secur_3

Available-for-sale debt securities (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2019USD ($)security	Jun. 30, 2018USD ($)	Jun. 30, 2019USD ($)security	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)security
Schedule of Available-for-sale Securities [Line Items]
Realized (gain) on available-for-sale debt securities	$ 13,000		$ 13,000
Realized loss on available-for-sale debt securities		$ 1,310,000		$ 2,473,000
Fair market value of investments in an unrealized loss position	$ 9,600,000		$ 9,600,000		$ 117,200,000
Number of debt securities | security	3		3		37
Number of available-for-sale securities in an unrealized loss position for more than one year | security	0		0
Cash equivalents
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 10,241,000		$ 10,241,000
Aggregate estimated fair value	10,241,000		10,241,000
Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	98,724,000		98,724,000
Gross unrealized gains	110,000		110,000
Gross unrealized losses	(2,000)		(2,000)
Aggregate estimated fair value	98,832,000		98,832,000
Corporate Debt Securities Maturity Period Less Than Three Months | Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	35,703,000		35,703,000
Gross unrealized gains	18,000		18,000
Aggregate estimated fair value	35,721,000		35,721,000
Money Market Funds Maturity Period Less Than Three Months | Cash equivalents
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	10,241,000		10,241,000
Aggregate estimated fair value	10,241,000		10,241,000
Corporate Debt Securities Maturity Period Three Months To One Year | Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	56,027,000		56,027,000
Gross unrealized gains	85,000		85,000
Gross unrealized losses	(2,000)		(2,000)
Aggregate estimated fair value	56,110,000		56,110,000
Agency Bond Maturity Period Three Months To One Year | Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	3,992,000		3,992,000
Gross unrealized gains	7,000		7,000
Aggregate estimated fair value	3,999,000		3,999,000
Certificate of Deposit Maturity Period Less Than Three Months | Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	3,002,000		3,002,000
Aggregate estimated fair value	$ 3,002,000		$ 3,002,000
Minimum | Money Market Funds Maturity Period Less Than Three Months | Cash equivalents
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Securities Debt Maturity Period			3 years
Minimum | Corporate Debt Securities Maturity Period Three Months To One Year | Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Securities Debt Maturity Period			3 months
Minimum | Agency Bond Maturity Period Three Months To One Year | Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Securities Debt Maturity Period			3 months
Minimum | Certificate of Deposit Maturity Period Three Months To One Year | Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Securities Debt Maturity Period			3 months
Maximum | Corporate Debt Securities Maturity Period Three Months To One Year | Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Securities Debt Maturity Period			1 year
Maximum | Agency Bond Maturity Period Three Months To One Year | Marketable securities
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Securities Debt Maturity Period			1 year

Other current assets (Details)

Other current assets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Other current assets
Corporate tax receivable	$ 26,328	$ 16,459
Prepayments	8,600	6,279
Clinical materials	1,755	1,087
VAT receivable	636	1,505
Other current assets	599	439
Total	$ 37,918	$ 25,769

Accrued expenses and other cu_3

Accrued expenses and other current liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accrued expenses and other current liabilities
Accrued clinical and development expenditure	$ 9,769	$ 9,637
Accrued employee expenses	5,678	7,553
Other accrued expenditure	2,739	2,422
Other	409	742
Total	$ 18,595	$ 20,354

Share-based compensation - Shar

Share-based compensation - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Total share-based compensation expense included in the consolidated statements of operations
Total share-based compensation expense	$ 3,196	$ 4,079	$ 6,675	$ 8,411
Research and development
Total share-based compensation expense included in the consolidated statements of operations
Total share-based compensation expense	786	2,071	2,807	4,285
General and administrative
Total share-based compensation expense included in the consolidated statements of operations
Total share-based compensation expense	$ 2,410	$ 2,008	$ 3,868	$ 4,126

Share-based compensation - Opti

Share-based compensation - Options (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based compensation
Number of options granted (in shares)	936,696	1,435,685	11,743,896	11,430,341
Weighted average fair value (in dollars per share)	$ 0.39	$ 1.18	$ 0.54	$ 0.80
Number of additional options with a nominal exercise price granted	459,240	151,056	6,957,366	6,703,692
Weighted average fair value of options with a nominal exercise price	$ 0.70	$ 1.88	$ 0.93	$ 1.35