MeiraGTx (MGTX) 10-Q 10 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 01, 2021
Document And Entity Information [Abstract]
Entity Registrant Name	MeiraGTx Holdings plc
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-38520
Document Period End Date	Sep. 30, 2021
Entity Incorporation, State or Country Code	E9
Entity Tax Identification Number	98-1448305
Entity Address, Address Line One	450 East 29th Street
Entity Address, Address Line Two	14th Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10016
City Area Code	646
Local Phone Number	860-7985
Title of 12(b) Security	Ordinary Shares,$0.00003881 par value per share
Trading Symbol	MGTX
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		44,448,624
Entity Central Index Key	0001735438
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 143,634	$ 209,520
Accounts receivable - related party	16,775	38,479
Prepaid expenses	8,840	7,082
Tax incentive receivable	5,383	12,930
Other current assets	2,299	4,565
Total Current Assets	176,931	272,576
Property and equipment, net	63,699	44,042
Intangible assets, net	1,861	2,119
In-process research and development	803	852
Security deposits	1,166	812
Other assets	201	214
Equity method and other investments	6,665
Right-of-use assets	52,010	43,082
TOTAL ASSETS	303,336	363,697
CURRENT LIABILITIES:
Accounts payable	11,421	7,134
Accrued expenses	21,926	20,861
Lease obligations, current	3,280	2,583
Deferred revenue - related party, current	23,003	23,545
Other current liabilities		24
Total Current Liabilities	59,630	54,147
Deferred revenue - related party	32,488	49,297
Lease obligations	21,262	19,666
Asset retirement obligations	1,916	1,814
Deferred income tax liability	201	214
TOTAL LIABILITIES	115,497	125,138
COMMITMENTS (Note 10)
SHAREHOLDERS' EQUITY:
Ordinary Shares, $0.00003881 par value, 1,288,327,750 authorized, 44,316,385 and 44,189,150 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	2	2
Capital in excess of par value	521,420	504,482
Accumulated other comprehensive loss	(2,906)	(4,897)
Accumulated deficit	(330,677)	(261,028)
Total Shareholders' Equity	187,839	238,559
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 303,336	$ 363,697

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.00003881	$ 0.00003881
Common stock, shares authorized	1,288,327,750	1,288,327,750
Common stock, shares issued	44,316,385	44,189,150
Common stock, shares outstanding	44,316,385	44,189,150

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
License revenue - related party	$ 6,947	$ 5,092	$ 16,658	$ 11,775
Operating expenses:
General and administrative	7,887	8,896	28,214	32,200
Research and development	21,612	4,626	53,512	28,911
Total operating expenses	29,499	13,522	81,726	61,111
Loss from operations	(22,552)	(8,430)	(65,068)	(49,336)
Other non-operating income (expense):
Foreign currency (loss) gain	(3,366)	1,875	(4,600)	767
Interest income	32	158	188	1,141
Interest expense	(59)	(35)	(169)	(103)
Net loss	(25,945)	(6,432)	(69,649)	(47,531)
Other comprehensive income (loss):
Foreign currency translation gain (loss)	2,669	(4,121)	1,991	342
Total comprehensive loss	(23,276)	(10,553)	(67,658)	(47,189)
Net loss	$ (25,945)	$ (6,432)	$ (69,649)	$ (47,531)
Basic net loss per ordinary share	$ (0.59)	$ (0.17)	$ (1.58)	$ (1.29)
Diluted net loss per ordinary share	$ (0.59)	$ (0.17)	$ (1.58)	$ (1.29)
Weighted-average number of ordinary shares outstanding, basic	44,170,299	37,223,375	44,094,873	36,940,372
Weighted-average number of ordinary shares outstanding, diluted	44,170,299	37,223,375	44,094,873	36,940,372

CONSOLIDATED STATEMENT OF SHARE

CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Ordinary Shares [Member]Visiogene License Agreement	Ordinary Shares [Member]	Capital in Excess of Par Value [Member]Visiogene License Agreement	Capital in Excess of Par Value [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Visiogene License Agreement	Total
Beginning Balance at Dec. 31, 2019		$ 1		$ 395,631	$ (1,794)	$ (203,036)		$ 190,802
Beginning Balance, Shares at Dec. 31, 2019		36,791,906
Exercise of share options				175				175
Exercise of share options, shares		26,010
Share-based compensation				5,683				5,683
Other comprehensive income (loss)					3,946			3,946
Net loss						(15,681)		(15,681)
Balance at Mar. 31, 2020		$ 1		401,489	2,152	(218,717)		184,925
Balance, Shares at Mar. 31, 2020		36,817,916
Beginning Balance at Dec. 31, 2019		$ 1		395,631	(1,794)	(203,036)		190,802
Beginning Balance, Shares at Dec. 31, 2019		36,791,906
Other comprehensive income (loss)								342
Net loss								(47,531)
Balance at Sep. 30, 2020		$ 1		431,103	(1,451)	(250,567)		179,086
Balance, Shares at Sep. 30, 2020		38,412,163
Beginning Balance at Mar. 31, 2020		$ 1		401,489	2,152	(218,717)		184,925
Beginning Balance, Shares at Mar. 31, 2020		36,817,916
Share-based compensation				5,056				5,056
Issuance of shares in connection with asset acquisitions				7,685				7,685
Issuance of shares in connection with asset acquisitions, shares		544,500
Other comprehensive income (loss)					518			518
Net loss						(25,418)		(25,418)
Balance at Jun. 30, 2020		$ 1		414,230	2,670	(244,135)		172,766
Balance, Shares at Jun. 30, 2020		37,362,416
Exercise of share options				478				478
Exercise of share options, shares		56,299
Share-based compensation				3,738				3,738
Other comprehensive income (loss)					(4,121)			(4,121)
Issuance of shares, net of issuance costs				12,657				12,657
Issuance of shares, net of issuance costs, shares		993,448
Net loss						(6,432)		(6,432)
Balance at Sep. 30, 2020		$ 1		431,103	(1,451)	(250,567)		179,086
Balance, Shares at Sep. 30, 2020		38,412,163
Beginning Balance at Dec. 31, 2020		$ 2		504,482	(4,897)	(261,028)		238,559
Beginning Balance, Shares at Dec. 31, 2020		44,189,150
Exercise of share options				141				141
Exercise of share options, shares		17,923
Share-based compensation				4,817				4,817
Issuance of shares in connection with equity method and other investments			$ 1,165				$ 1,165
Issuance of shares in connection with equity method and other investments, shares	75,000
Other comprehensive income (loss)					(271)			(271)
Net loss						(23,618)		(23,618)
Balance at Mar. 31, 2021		$ 2		510,605	(5,168)	(284,646)		220,793
Balance, Shares at Mar. 31, 2021		44,282,073
Beginning Balance at Dec. 31, 2020		$ 2		504,482	(4,897)	(261,028)		$ 238,559
Beginning Balance, Shares at Dec. 31, 2020		44,189,150
Exercise of share options, shares								52,235
Other comprehensive income (loss)								$ 1,991
Net loss								(69,649)
Balance at Sep. 30, 2021		$ 2		521,420	(2,906)	(330,677)		187,839
Balance, Shares at Sep. 30, 2021		44,316,385
Beginning Balance at Mar. 31, 2021		$ 2		510,605	(5,168)	(284,646)		220,793
Beginning Balance, Shares at Mar. 31, 2021		44,282,073
Exercise of share options				219				219
Exercise of share options, shares		27,380
Share-based compensation				5,203				5,203
Other comprehensive income (loss)					(407)			(407)
Net loss						(20,086)		(20,086)
Balance at Jun. 30, 2021		$ 2		516,027	(5,575)	(304,732)		205,722
Balance, Shares at Jun. 30, 2021		44,309,453
Exercise of share options				54				54
Exercise of share options, shares		6,932
Share-based compensation				5,339				5,339
Other comprehensive income (loss)					2,669			2,669
Net loss						(25,945)		(25,945)
Balance at Sep. 30, 2021		$ 2		$ 521,420	$ (2,906)	$ (330,677)		$ 187,839
Balance, Shares at Sep. 30, 2021		44,316,385

CONSOLIDATED STATEMENT OF SHA_2

CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (Parenthetical)	3 Months Ended
	Sep. 30, 2020USD ($)
At-the-market offering [Member]
Stock issuance costs	$ 506

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (69,649)	$ (47,531)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	15,359	14,477
Foreign currency loss (gain)	4,600	(767)
Depreciation and amortization	5,811	2,821
Net change in right-of-use assets and liabilities	161	30
Loss on disposal of equipment, furniture and fixtures		116
Gain on termination of lease liability		(144)
Amortization of interest on asset retirement obligations	112	101
Issuance of shares in connection with asset acquisition		7,685
(Increase) decrease in operating assets:
Accounts receivable - related party	21,484	(3,725)
Prepaid expenses	(1,827)	535
Tax incentive receivable	7,518	4,628
Other current assets	2,387	1,106
Security deposits	(372)	191
Other assets	(147)
Increase (decrease) in operating liabilities:
Accounts payable	3,898	481
Accrued expenses	(2,012)	(2,634)
Other current liabilities	(23)
Deferred revenue - related party	(16,658)	(11,775)
Net cash used in operating activities	(29,358)	(34,405)
Cash flows from investing activities:
Purchase of property and equipment	(21,982)	(12,909)
Payment for right-of-use asset	(8,866)	(13,877)
Equity method and other investments	(5,500)
Net cash used in investing activities	(36,348)	(26,786)
Cash flows from financing activities:
Payments on lease obligations - financing leases	(1)	(19)
Exercise of share options	414	653
Proceeds from the issuance of ordinary shares		13,163
Issuance costs in connection with ordinary shares		(506)
Net cash provided by financing activities	413	13,291
Net decrease in cash and cash equivalents	(65,293)	(47,900)
Effect of exchange rate changes on cash	(593)	(122)
Cash and cash equivalents at beginning of period	209,520	227,357
Cash and cash equivalents at end of period	143,634	179,335
Supplemental disclosure of non-cash transactions:
Issuance of shares in connection with equity method and other investments	1,165
Fixed asset acquisition included in accounts payable and accrued expenses at end of period	4,027	1,192
Right-of-use assets obtained in exchange for lease liabilities	4,424
Issuance of shares in connection with asset acquisition		$ 7,685
Supplemental disclosure of cash flow information:
Cash paid for interest	$ 57

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2021
Organization And Nature Of Business Textual [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation: The Company MeiraGTx Holdings plc and subsidiaries (the “Company” or “Meira Holdings”), an exempted company incorporated under the laws of the Cayman Islands, is a vertically integrated, clinical-stage gene therapy company with six programs in clinical development and a broad pipeline of preclinical and research programs. The Company has core capabilities in viral vector design and optimization and gene therapy manufacturing, as well as a potentially transformative gene regulation technology. Led by an experienced management team, the Company has taken a portfolio approach by licensing, acquiring and developing technologies that give depth across both product candidates and indications. The Company’s initial focus is on three distinct areas of unmet medical need: ocular, including inherited retinal diseases and large degenerative diseases, neurodegenerative diseases and severe forms of xerostomia. Though initially focusing on the eye, central nervous system and salivary gland, the Company intends to expand its focus in the future to develop additional gene therapy treatments for patients suffering from a range of serious diseases. The Company also owns and operates a current good manufacturing practices, or cGMP, multi-product, multi-viral vector manufacturing facility in London, United Kingdom, which includes fill and finish capabilities and can supply the Company’s clinical and potential commercial material. Additionally, the Company expanded its manufacturing and supply chain capabilities by acquiring a second cGMP viral vector manufacturing facility and its first cGMP plasmid and DNA production facility in Shannon, Ireland. The Company completed the acquisition of these facilities in January 2021. Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). Interim Financial Statements The accompanying condensed consolidated financial statements have been prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all the information and footnotes required by GAAP for complete consolidated financial statements. In the opinion of management, the condensed consolidated financial statements include all adjustments (consisting of normal recurring accruals) necessary in order to make the condensed consolidated financial statements not misleading. Operating results for the nine-month period ended September 30, 2021 are not necessarily indicative of the final results that may be expected for the year ending December 31, 2021. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto for the year ended December 31, 2020 included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2020 (the “Form 10-K”). Liquidity The Company has not yet achieved profitable operations. There is no assurance that profitable operations, if ever achieved, could be sustained on a continuing basis. In addition, development activities, clinical and preclinical testing, and commercialization of the Company’s product candidates will require significant additional financing. The Company’s accumulated deficit at September 30, 2021 totaled $330.7 million, and management expects to incur substantial losses in future periods. The success of the Company is subject to certain risks and uncertainties, including, among others: uncertainty of product development; competition in the Company’s field of use; uncertainty of capital availability; uncertainty in the Company’s ability to enter into agreements with collaborative partners; expanding and protecting the Company’s intellectual property portfolio, dependence on third parties, dependence on key personnel and the COVID-19 pandemic and mitigation measures. For the nine-months ended September 30, 2021, the Company used $29.4 million in cash flows from operations and there are no assurances that the Company will generate positive cash flows in the future. Additionally, there are no assurances that the Company will be successful in obtaining an adequate level of financing for the development and commercialization of its product candidates. As of September 30, 2021, the Company had cash and cash equivalents in the amount of $143.6 million, which consisted of depository accounts. On January 30, 2019, the Company entered into a collaboration, option and license agreement with Janssen Pharmaceuticals, Inc. (“Janssen”), one of the Janssen Pharmaceuticals Companies of Johnson & Johnson (the “Collaboration Agreement”), for the research, development and commercialization of gene therapies for the treatment of inherited retinal diseases (“IRD”). Under the terms of the Collaboration Agreement, the Company receives funding for certain research, manufacturing, clinical development and commercialization costs, potential additional milestone payments upon the achievement of such milestones and royalties on future net sales of products. The Company estimates that its cash and cash equivalents on-hand at September 30, 2021 will be sufficient to cover its expenses for at least the next twelve months from the date of issuance of these condensed consolidated financial statements. Risks and Uncertainties The Company operates in an industry that is subject to intense competition, government regulation and rapid technological change. The Company’s operations are subject to significant risk and uncertainties including financial, operational, technological, regulatory and other risks, including the potential risk of business failure. There are also many uncertainties regarding the pandemic caused by the novel coronavirus, or COVID-19, and the Company continues to closely monitor the impact of the pandemic on all aspects of its business, including how the pandemic will impact its financial condition, liquidity, operations, clinical studies, employees, vendors, and industry. While the pandemic did not materially affect the Company's financial results and business operations during the nine-month period ended September 30, 2021, the Company is unable to predict the impact that COVID-19 will have on its financial position and operating results in future periods due to numerous uncertainties. The Company will continue to assess the evolving impact of the COVID-19 pandemic and will make adjustments to its operations as necessary. The Company’s capital resources and operations to date have been funded primarily with the proceeds from the Collaboration Agreement and private and public equity offerings. In the future, the Company may seek to raise additional capital through equity offerings, debt financings, marketing and distribution arrangements and other collaborations, strategic alliances and licensing arrangements or other sources to enable it to complete the development and potential commercialization of its product candidates. The COVID-19 outbreak and mitigation measures also have had, and may continue to have, an adverse impact on global economic conditions, which could have an adverse effect on the Company’s ability to raise capital when needed.

Summary of Significant Accounti

Summary of Significant Accounting Policies and Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies and Recent Accounting Pronouncements	2. Summary of Significant Accounting Policies and Recent Accounting Pronouncements: Certain of the Company’s significant accounting policies are described below. All of the Company’s significant accounting policies are disclosed in the notes to the audited consolidated financial statements as of and for the year ended December 31, 2020 included in the Company’s Form 10-K. Since the date of such financial statements, the Company has adopted the new accounting pronouncements which are disclosed further in this note. Consolidation The accompanying condensed consolidated financial statements include the accounts of Meira Holdings and its wholly owned subsidiaries: MeiraGTx Limited, a limited company incorporated under the laws of England and Wales; MeiraGTx, LLC, a Delaware limited liability company (“Meira LLC”); MeiraGTx UK II Limited, a limited company incorporated under the laws of England and Wales (“Meira UK II”); MeiraGTx Ireland DAC, a designated activity company incorporated under the laws of Ireland (“Meira Ireland”); MeiraGTx Netherlands, B.V., a private company with limited liability incorporated under the laws of the Netherlands (“Meira Netherlands”); MeiraGTx Belgium, a private company with limited liability incorporated under the laws of Belgium (“Meira Belgium”); BRI-Alzan, Inc., a Delaware corporation (“BRI-Alzan”); MeiraGTx Bio, Inc., a Delaware corporation (“Meira Bio”); MeiraGTx B.V., a private company with limited liability incorporated under the laws of the Netherlands (“Meira B.V.”); MeiraGTx Neurosciences, Inc., a Delaware corporation (“Meira Neuro”); and MeiraGTx UK Limited, a limited company incorporated under the laws of England and Wales (“Meira UK”). All intercompany balances and transactions between the consolidated companies have been eliminated in consolidation. Use of Estimates Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these condensed consolidated financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. This process may result in actual results differing materially from those estimated amounts used in the preparation of the financial statements if these results differ from historical experience, or other assumptions do not turn out to be substantially accurate, even if such assumptions are reasonable when made. In preparing these condensed consolidated financial statements, management used significant estimates in the following areas, among others: collaboration revenue, the accounting for research and development costs, share-based compensation, leases, asset retirement obligations and tax incentive receivable. Additionally, the Company has made estimates of the impact of the COVID-19 pandemic within the condensed consolidated financial statements and there may be changes to those estimates in future periods. Actual results may differ from these estimates. Fair Value Measurements Fair value is defined as the price that would be received upon sale of an asset or paid upon transfer of a liability in an orderly transaction between market participants at the measurement date and in the principal or most advantageous market for that asset or liability. The fair value should be calculated based on assumptions that market participants would use in pricing the asset or liability, not on assumptions specific to the entity. In addition, the fair value of liabilities should include consideration of non-performance risk including the Company’s credit risk. The Company follows ASC Topic 820, Fair Value Measurements and Disclosures around fair value and establishes a fair value hierarchy for valuation inputs. The hierarchy prioritizes the inputs into three levels based on the extent to which inputs used in measuring fair value are observable in the market. Each fair value measurement is reported in one of the three levels which are determined by the lowest level input that is significant to the fair value measurement in its entirety. These levels are: ● Level 1: Observable inputs such as quoted prices in active markets for identical assets the reporting entity has the ability to access as of the measurement date; ● Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly; and ● Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. Equity Method and Other Investments The Company accounts for equity investments under the equity method of accounting when the requirements for consolidation are not met, and the Company has significant influence over the operations of the investee. Equity method investments are initially recorded at cost and subsequently adjusted for the Company’s share of net income or loss and cash contributions and distributions and are included in equity method and other investments in the accompanying condensed consolidated balance sheets. Equity investments that do not result in consolidation and are not accounted for under the equity method are measured at fair value, with any changes in fair value recognized in net income (loss). For any such investments that do not have readily determinable fair values, the Company elects the measurement alternative to measure the investments at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Equity method investments are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. If it is determined that a loss in value of the equity method investment is other than temporary, an impairment loss is measured based on the excess of the carrying amount of an investment over its estimated fair value. Impairment analyses are based on current plans, intended holding periods, and available information at the time the analysis is prepared. Leases The Company accounts for leases in accordance with ASC 842. The Company determines if an arrangement is a lease at contract inception. A lease exists when a contract conveys the right to control the use of identified property, plant, or equipment for a period of time in exchange for consideration. The definition of a lease embodies two conditions: (1) there is an identified asset in the contract that is land or a depreciable asset (i.e., property, plant, and equipment), and (2) the Company has the right to control the use of the identified asset. The Company accounts for the lease and non-lease components as a single lease component. From time to time the Company enters into direct financing lease arrangements that include a lessee obligation to purchase the leased asset at the end of the lease term, a bargain purchase option, or provides for minimum lease payments with a present value of 90% or more of the fair value of the leased asset at the date of lease inception. Operating leases where the Company is the lessee are included in right-of-use (“ROU”) assets and lease obligations are included on the Company’s consolidated balance sheets. The lease obligations are initially and subsequently measured at the present value of the unpaid lease payments at the lease commencement date and subsequent reporting periods. Finance leases where the Company is the lessee are included in ROU assets and lease obligations on the Company’s consolidated balance sheets. The lease obligations are initially measured in the same manner as for operating leases and are subsequently measured at amortized cost using the effective interest method. Key estimates and judgments include how the Company determined (1) the discount rate used to discount the unpaid lease payments to present value, (2) lease term and (3) lease payments. ASC 842 requires a lessee to discount its unpaid lease payments using the interest rate implicit in the lease or, if that rate cannot be readily determined, its incremental borrowing rate. As most of the Company’s leases where it is the lessee do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The Company’s incremental borrowing rate for a lease is the rate of interest it would have to pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. The Company uses the implicit rate when readily determinable. The lease term for all of the Company’s leases includes the non-cancellable period of the lease plus any additional periods covered by either a lessee option to extend (or not to terminate) the lease that is reasonably certain to be exercised, or an option to extend (or not to terminate) the lease controlled by the lessor. The ROU asset is initially measured at cost, which comprises the initial amount of the lease liability adjusted for lease payments made at or before the lease commencement date less any lease incentives received. For operating leases, the ROU asset is subsequently measured throughout the lease term at the carrying amount of the lease liability, minus any accrued lease payments, less the unamortized balance of lease incentives received. Lease expense for lease payments is recognized on a straight-line basis over the lease term. For finance leases, the ROU asset is subsequently amortized using the straight-line method from the lease commencement date to the earlier of the end of its useful life or the end of the lease term unless the lease transfers ownership of the underlying asset, or the Company is reasonably certain to exercise an option to purchase the underlying asset. In those cases, the ROU asset is amortized over the useful life of the underlying asset. Amortization of the ROU asset is recognized and presented separately from interest expense on the lease liability. The Company has elected not to recognize ROU assets and lease liabilities for all short-term leases that have a lease term of 12 months or less at lease commencement. Lease payments associated with short-term leases are recognized as an expense on a straight-line basis over the lease term. Asset Retirement Obligations Accounting for asset retirement obligations requires legal obligations associated with the retirement of long-lived assets to be recognized at fair value when incurred and capitalized as part of the related long-lived asset. In the absence of quoted market prices, the Company estimates the fair value of its asset retirement obligations using Level 3 present value techniques, in which estimates of future cash flows associated with retirement activities are discounted using a credit-adjusted risk-free rate. Asset retirement obligations currently reported as other liabilities on the condensed consolidated balance sheet were measured during a period of historically low interest rates. The impact on measurements of new asset retirement obligations using different rates in the future may be significant. The Company uses estimates to determine the asset retirement obligations at the end of the lease term and discounts such asset retirement obligations using an estimated discount rate. Interest on the discounted asset retirement obligation is amortized over the term of the lease using the effective interest method and is recorded as interest expense in the condensed consolidated statements of operations and comprehensive loss. The change in asset retirement obligations is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Nine-Month Periods Ended September 30, ​ ​ 2021 ​ 2020 Balance at beginning of period $ 1,814 $ 1,655 Amortization of interest ​ 112 ​ 101 Effects of exchange rate ​ (10) ​ (14) Balance at end of period ​ $ 1,916 ​ $ 1,742 ​ Collaboration Arrangements The Company evaluates its collaborative arrangements pursuant to ASC 808, Collaborative Arrangements Revenue from Contracts with Customers ASC 808 does not address recognition or measurement matters related to collaborative arrangements. Payments between participants pursuant to a collaborative arrangement that are within the scope of other authoritative accounting literature on income statement classification are accounted for using the relevant provisions of that literature. If the payments are not within the scope of other authoritative accounting literature, the income statement classification for the payments is based on an analogy to authoritative accounting literature or if there is no appropriate analogy, a reasonable, rational and consistently applied accounting policy election. Payments received from a collaboration partner to which this policy applies may include upfront payments in respect of a license of intellectual property, development and commercialization-based milestones, and royalties. Refer to the discussion in Note 8 for further information related to the accounting for the Collaboration Agreement. Revenue Recognition Arrangements with collaborators may include licenses to intellectual property, research and development services, manufacturing services for clinical and commercial supply, and participation on joint steering committees. The Company evaluates the promised goods or services to determine which promises, or group of promises, represent performance obligations. In contemplation of whether a promised good or service meets the criteria required of a performance obligation, the Company considers the stage of development of the underlying intellectual property, the capabilities and expertise of the customer relative to the underlying intellectual property, and whether the promised goods or services are integral to or dependent on other promises in the contract. When accounting for an arrangement that contains multiple performance obligations, the Company must develop judgmental assumptions, which may include market conditions, reimbursement rates for personnel costs, development timelines and probabilities of regulatory success to determine the stand-alone selling price for each performance obligation identified in the contract. When the Company concludes that a contract should be accounted for as a combined performance obligation and recognized over time, the Company must then determine the period over which revenue should be recognized and the method by which to measure revenue. The Company generally recognizes revenue using a cost-based input method. The Collaboration Agreement with Janssen is accounted for under ASC 808, however, as ASC 808 does not address recognition or measurement matters such as determining the appropriate unit of accounting or when the recognition criteria are met, the Company accounts for the consideration received from Janssen in accordance with ASC 606. In accordance with ASC 606, the Company recognizes revenue when its customer or collaborator obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, it performs the following five steps: i. identify the contract(s) with a customer; ii. identify the performance obligations in the contract; iii. determine the transaction price; iv. allocate the transaction price to the performance obligations within the contract; and v. recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it determines that it is probable it will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be by analogy within the scope of ASC 606, the Company assesses the goods or services promised within the contract to determine whether each promised good or service is a performance obligation. The promised goods or services in the Company’s arrangements typically consist of a license to the Company’s intellectual property and research, development and manufacturing services. The Company may provide options to additional items in such arrangements, which are accounted for as separate contracts when the customer elects to exercise such options, unless the option provides a material right to the customer. Performance obligations are promises in a contract to transfer a distinct good or service to the customer that (i) the customer can benefit from on its own or together with other readily available resources, and (ii) is separately identifiable from other promises in the contract. Goods or services that are not individually distinct performance obligations are combined with other promised goods or services until such combined group of promises meet the requirements of a performance obligation. The Company determines transaction price based on the amount of consideration the Company expects to receive for transferring the promised goods or services in the contract. Consideration may be fixed, variable, or a combination of both. At contract inception for arrangements that include variable consideration, the Company estimates the probability and extent of consideration it expects to receive under the contract utilizing either the most likely amount method or expected amount method, whichever best estimates the amount expected to be received. The Company then considers any constraints on the variable consideration and includes in the transaction price variable consideration to the extent it is deemed probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. The Company then allocates the transaction price to each performance obligation based on the relative standalone selling price and recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) control is transferred to the customer and the performance obligation is satisfied. For performance obligations which consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The Company records amounts as accounts receivable when the right to consideration is deemed unconditional. When consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract, a contract liability is recorded as deferred revenue. Amounts received prior to satisfying the revenue recognition criteria are recognized as deferred revenue in the Company’s condensed consolidated balance sheet. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue – related party, current. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue – related party. The Company’s collaboration revenue arrangements include the following: Up-front License Fees: If a license is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from nonrefundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments: At the inception of an agreement that includes research and development milestone payments, the Company evaluates each milestone to determine when and how much of the milestone to include in the transaction price. The Company first estimates the amount of the milestone payment that the Company could receive using either the expected value or the most likely amount approach. The Company primarily uses the most likely amount approach as that approach is generally most predictive for milestone payments with a binary outcome. Then, the Company considers whether any portion of that estimated amount is subject to the variable consideration constraint (that is, whether it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty.) The Company updates the estimate of variable consideration included in the transaction price at each reporting date which includes updating the assessment of the likely amount of consideration and the application of the constraint to reflect current facts and circumstances. Royalties: For arrangements that include sales-based royalties, including milestone payments based on a level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any revenue related to sales-based royalties or milestone payments based on the level of sales. Research and Development Services: The Company is incurring research and development costs, with Janssen responsible for up to 100% of the costs, depending on the type of research and development services being performed. The Company records costs associated with the development activities as research and development expenses in the condensed consolidated statements of operations and comprehensive loss consistent with ASC 730, Research and Development Research and Development Research and development costs are charged to expense as incurred. These costs include, but are not limited to, employee-related expenses, including salaries, benefits and travel of the Company’s research and development personnel; expenses incurred under agreements with contract research organizations and investigative sites that conduct clinical and preclinical studies and for the drug product for the clinical studies and preclinical activities; facilities; supplies; rent, insurance, certain legal fees, share-based compensation, depreciation and other costs associated with clinical and preclinical activities and regulatory operations. Research funding under collaboration agreements and refundable research and development credits / tax credits are recorded as an offset to these costs. Costs for certain development activities, such as Company funded outside research programs, are recognized based on an evaluation of the progress to completion of specific tasks with respect to their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the condensed consolidated financial statements as prepaid expenses or accrued expenses, as the case may be. Net Loss per Ordinary Share Basic net loss per ordinary share is computed by dividing net loss by the weighted average number of shares of the Company’s ordinary shares assumed to be outstanding during the period of computation. Diluted net loss per ordinary share is computed similar to basic net loss per share except that the denominator is increased to include the number of additional ordinary shares that would have been outstanding if the potential ordinary shares had been issued at the beginning of the year and if the additional ordinary shares were dilutive (treasury stock method) or the two-class method, whichever is more dilutive. For all periods presented, basic and diluted net loss per ordinary share are the same, as any additional ordinary share equivalents would be anti-dilutive. The following securities are considered to be ordinary share equivalents, but were not included in the computation of diluted net loss per ordinary share because to do so would have been anti-dilutive: ​ ​ ​ ​ ​ ​ ​ September 30, September 30, ​ 2021 2020 Share options 6,141,510 4,970,531 Restricted share units ​ 1,415,000 ​ 545,000 Restricted ordinary shares subject to forfeiture ​ 145,000 ​ — ​ 7,701,510 5,515,531 ​ Segment Information Management has concluded it has a single reporting segment for purposes of reporting financial condition and results of operations. The Company’s license revenue, research funding and deferred revenue from its Collaboration Agreement are generated in the United Kingdom. The following table summarizes non-current assets by geographical area (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2021 ​ 2020 United States ​ $ 23,947 ​ $ 17,536 United Kingdom ​ 43,728 ​ 44,487 European Union ​ ​ 58,730 ​ ​ 29,098 ​ ​ $ 126,405 ​ $ 91,121 ​ Recent Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments

Equity Method and Other Investm

Equity Method and Other Investments	9 Months Ended
	Sep. 30, 2021
Long-term Investments [Abstract]
Equity Method and Other Investments	3. Equity Method and Other Investments The Company’s investments consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2021 Investee Investment Type Ownership Percentage Carrying Value Cost Basis Visiogene LLC ​ Equity Method Investment ​ 25 % ​ $ 5,165 ​ $ 5,165 Other ​ Equity Investment ​ 3 % ​ ​ 1,500 ​ ​ 1,500 Total equity method and other investments ​ ​ ​ ​ ​ ​ $ 6,665 ​ $ 6,665 ​ Visiogene LLC On January 4, 2021, the Company and Visiogene LLC (“Visiogene”) entered into a License and Investment Agreement (“Visiogene License Agreement”) for an exclusive, worldwide license to certain of Visiogene’s intellectual property relating to ocular gene therapy. Concurrently, the Company and Visiogene entered into a Preferred Unit Purchase Agreement (“Visiogene Unit Agreement”) pursuant to which the Company purchased 3,000,000 Visiogene preferred units. In connection with the two Visiogene agreements, the Company paid $5.0 million in cash and issued to Visiogene 75,000 ordinary shares of the Company with a fair market value of $1.2 million based on the closing price of the Company’s ordinary shares on the date of closing. The Company accounted for the payments under the Visiogene License Agreement and Visiogene Unit Agreement as a basket transaction and allocated $1.0 million to the Visiogene License Agreement and the remaining $5.2 million was allocated to the Visiogene preferred units. The $1.0 million allocated to the Visiogene License Agreement was expensed as acquired in-process research and development as the Company determined there was no alternative future use. The Company accounts for this investment using the equity method of accounting.

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2021
Payables and Accruals [Abstract]
Accrued Expenses	4. Accrued Expenses Accrued expenses for the periods presented are comprised of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2021 ​ 2020 Clinical trial costs ​ $ 11,509 ​ $ 10,261 Fixed assets ​ 3,107 ​ 949 Manufacturing costs ​ 2,923 ​ 1,886 Research and development ​ 1,813 ​ 893 Compensation and benefits ​ ​ 1,371 ​ ​ 3,791 Professional fees ​ 548 ​ 1,219 Consulting ​ 327 ​ 1,047 Other ​ ​ 328 ​ 815 ​ ​ $ 21,926 ​ $ 20,861 ​

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2021
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	5. Share-Based Compensation Equity Incentive Plans The Company’s 2018 Incentive Award Plan and 2016 Equity Incentive Plan (collectively, the “Plans”) were adopted by the Company’s board of directors and shareholders. Under the Plans, the Company has granted share options and restricted share units (“RSUs”) to selected officers, employees, non-employee members of the board of directors and non-employee consultants. The Company’s board of directors or a committee thereof administers the Plans. Upon the adoption of the 2018 Incentive Award Plan, the Company ceased issuing awards under the 2016 Equity Incentive Plan. Options ​ A summary of the Company’s share option activity related to employees, non-employee members of the board of directors and non-employee consultants as of December 31, 2020 and for the nine-month period ended September 30, 2021 is as follows (in thousands, except share and per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ Weighted- ​ Average ​ ​ ​ ​ ​ ​ Average ​ ​ Remaining ​ ​ ​ ​ Number of ​ Exercise ​ ​ Contractual ​ ​ ​ ​ Options ​ Price ​ ​ Life (years) ​ Outstanding at December 31, 2020 ​ 4,824,771 ​ $ 11.85 ​ 7.67 years Granted ​ 1,628,700 ​ $ 15.66 ​ ​ ​ Exercised ​ (52,235) ​ $ 7.92 ​ ​ ​ Expired ​ ​ (98,025) ​ $ 9.03 ​ ​ ​ ​ Forfeited ​ (161,701) ​ $ 15.19 ​ ​ ​ Outstanding at September 30, 2021 ​ 6,141,510 ​ $ 12.99 ​ ​ 7.60 years Options exercisable at September 30, 2021 ​ 3,272,190 ​ $ 10.69 ​ 6.68 years Aggregate intrinsic value of options outstanding as of September 30, 2021 ​ $ 14,914 ​ ​ ​ Aggregate intrinsic value of options exercisable as of September 30, 2021 ​ $ 13,090 ​ ​ ​ ​ Options granted under the Plans have a maximum contractual term of ten years. Options granted generally vest 25% on the first anniversary of the date of grant and the balance ratably over the next 36 months. Options granted to directors when they join the board generally vest in 36 equal monthly installments following the date of grant, and annual options granted to directors generally vest on the earlier of the first anniversary of the date of grant or the day before the Company’s annual meeting of shareholders after the date of grant. The total share-based compensation expense recorded in connection with the options was $3.6 million and $3.0 million, of which $1.4 million and $1.5 million was recorded as general and administrative expense and $2.2 million and $1.5 million was recorded as research and development expense during the three-month periods ended September 30, 2021 and 2020, respectively. The total share-based compensation expense recorded in connection with the options was $11.3 million and $9.6 million, of which $4.6 million and $5.3 million was recorded as general and administrative expense and $6.7 million and $4.3 million was recorded as research and development expense during the nine-month periods ended September 30, 2021 and 2020, respectively. The total fair value of options vested during the three-month periods ended September 30, 2021 and 2020 was $2.5 million and $1.3 million, respectively. The total fair value of options vested during the nine-month periods ended September 30, 2021 and 2020 was $12.2 million and $6.8 million, respectively. The weighted-average grant date fair value of options granted during the nine-month periods ended September 30, 2021 and 2020 was $11.54 per share and $12.73 per share, respectively. The grant date fair values of the share options granted were estimated using the Black-Scholes option valuation model with the following ranges of assumptions: ​ ​ ​ ​ ​ ​ ​ 2021 2020 Risk-free interest rate 0.62 - 1.14% 0.32 - 2.56% Expected volatility 90% 90% Expected dividend yield 0% 0% Expected life (in years) 5.5 - 6.1 5.5 - 6.1 ​ As of September 30, 2021, the total compensation expense relating to unvested options granted that had not yet been recognized was $29.5 million, which is expected to be realized over a period of 4.0 years. The Company will issue shares upon exercise of options from ordinary shares reserved under the Plans. Restricted Share Units A summary of the Company’s RSU activity related to employees, non-employee members of the board of directors and non-employee consultants as of December 31, 2020 and for the nine-month period ended September 30, 2021 is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ Number of ​ Average ​ ​ ​ Restricted ​ Grant Date ​ ​ ​ Share Units ​ Fair Value Outstanding at December 31, 2020 ​ 545,000 ​ $ 20.02 Granted ​ 870,000 ​ $ 15.36 Vested ​ ​ — ​ $ — Forfeited ​ — ​ $ — Outstanding at September 30, 2021 ​ 1,415,000 ​ $ 17.16 ​ RSUs granted generally vest 50% on the second anniversary of the date of grant and 25% on the third and fourth Total share-based compensation expense recorded in connection with the RSUs was $1.7 million and $0.7 million, of which $1.5 million and $0.6 million was recorded as general and administrative expense and $0.2 million and $0.1 million was recorded as research and development expense during the three-month periods ended September 30, 2021 and 2020, respectively. Total share-based compensation expense recorded in connection with the RSUs was $4.1 million and $2.0 million, of which $3.5 million and $1.9 million was recorded as general and administrative expense and $0.6 million and $0.1 million was recorded as research and development expense during the nine-month periods ended September 30, 2021 and 2020, respectively. As of September 30, 2021, the total compensation expense relating to unvested RSUs granted that had not yet been recognized was $17.5 million, which is expected to be realized over a period of 4.0 years. Restricted Ordinary Shares On June 7, 2018, 1,306,348 restricted ordinary shares, which represented 5% of the fully-diluted outstanding shares of the Company as of such date, were issued to certain members of senior management in accordance with their employment agreements. One-third These restricted ordinary shares were fully vested as of June 2020. Total compensation expense in connection with issuance of those restricted ordinary shares, in the amount of $6.5 million, of which $2.9 million was share-based and $3.6 million was paid in cash, was recorded as general and administrative expense during the nine-month period ended September 30, 2020. During the three-month and nine-month periods ended September 30, 2021 and 2020 the Company recognized total share-based compensation expense in the accompanying condensed consolidated statements of operations and comprehensive loss as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three-month periods ended September 30, ​ 2021 2020 Research and development ​ $ 2,436 ​ $ 1,560 General and administrative ​ 2,903 ​ 2,178 Total share-based compensation ​ $ 5,339 ​ $ 3,738 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine-month periods ended September 30, ​ 2021 2020 Research and development ​ $ 7,273 ​ $ 4,442 General and administrative ​ 8,086 ​ ​ 10,035 Total share-based compensation ​ $ 15,359 ​ $ 14,477 ​ The Company does not expect to realize any tax benefits from its share option activity or the recognition of share-based compensation expense because the Company currently has net operating losses and has a full valuation allowance against its deferred tax assets. Accordingly, no amounts related to excess tax benefits have been reported in cash flows from operations or cash flows from financing activities for the nine-month periods ended September 30, 2021 and 2020.

Ordinary Shares

Ordinary Shares	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Ordinary Shares	6. Ordinary Shares As discussed in Note 3, on January 4, 2021, the Company issued 75,000 ordinary shares in connection with the Visiogene transaction in the amount of $1.2 million. ​

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	7. Income Taxes The Company did not record a provision for income taxes for the three-month and nine-month periods ended September 30, 2021 and 2020, as the Company has generated losses for all periods. The Company periodically evaluates the realizability of its deferred tax assets based on all available evidence, both positive and negative. The realization of deferred tax assets is dependent on the Company’s ability to generate sufficient future taxable income during periods prior to the expiration of tax attributes to fully utilize these assets. The Company weighed both positive and negative evidence and determined that there is a continued need for a full valuation allowance on its deferred tax assets (after consideration of the reversal of the deferred tax liabilities for the ROU assets and fixed assets) in the United States, United Kingdom, Ireland and Netherlands as of September 30, 2021. Should the Company determine that it would be able to realize its remaining deferred tax assets in the foreseeable future, an adjustment to its remaining deferred tax assets would cause a material increase to income in the period such determination is made.

Related-Party Transactions

Related-Party Transactions	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Related-Party Transactions	8. Related-Party Transactions Collaboration and License Agreements Janssen Pharmaceuticals, Inc. On January 30, 2019, the Company entered into a Collaboration Agreement with Janssen for the research, development and commercialization of gene therapies for the treatment of IRDs. Under the agreement, Janssen paid the Company a non-refundable upfront fee of $100.0 million. Janssen and the Company will collaborate to develop the Company’s current clinical programs in retinitis pigmentosa and two genetic forms of achromatopsia, and Janssen has the exclusive right to commercialize these three product candidates (“Clinical IRD Product Candidates”) globally. Pursuant to the Collaboration Agreement, the Company and Janssen also agreed on a research collaboration to develop a pipeline of preclinical inherited retinal disease gene therapy candidates (“Research IRD Product Candidates”). The parties will select and prioritize the Research IRD Product Candidates and Janssen has the right to opt-in for a fee for each of the specified targets (each an “Option Target”) to obtain certain development, manufacturing and commercialization rights for the Research IRD Product Candidates. Unless terminated earlier under certain termination clauses, the Collaboration Agreement will continue in effect, on a product-by-product and country-by-country basis, until such time as the royalty terms expire in such country. The Company has determined enforceable rights exist in the Collaboration Agreement as the termination clauses are substantive termination penalties by way of the non-refundable upfront fee and the reversion of any licensed intellectual property granted to Janssen upon the termination of the agreement. On February 27, 2019, in connection with a private placement, the Company issued 2,898,550 ordinary shares to Johnson & Johnson Innovation – JJDC, Inc. (“JJDC”), the investment arm of Johnson and Johnson and owner of Janssen, on the same terms and conditions as the other investors in the offering. After the offering, JJDC became a related party. Clinical IRD Product Candidates Under the Collaboration Agreement, the Company and Janssen will jointly develop Clinical IRD Product Candidates to permit Janssen to commercialize such Clinical IRD Product Candidates under an exclusive license from the Company. In general, the Company will have the primary responsibility to develop each Clinical IRD Product Candidate in accordance with the development plan for each Clinical IRD Product Candidate, including where applicable, conducting any necessary research in order to submit the applicable regulatory filings to regulatory authorities. The Company will manufacture these products in its cGMP manufacturing facility for both clinical and commercial supply. Janssen will pay 100% of the clinical and commercialization costs of the products and the Company is eligible to receive untiered 20% royalties on net sales of products and additional development and commercialization milestones up to $340.0 million. Research IRD Product Candidates Under the Collaboration Agreement, the Company and Janssen will collaborate to develop Research IRD Product Candidates, with Janssen paying for the majority of the research costs. Janssen has the right to exclusively license any product coming out of the collaboration at the time of an investigational new drug application (“IND”) for an additional fee for each Research IRD Product Candidate. Janssen will then pay 100% of the clinical and commercialization costs for these Research IRD Product Candidates and the Company will receive an untiered royalty on net sales in the high teens as well as development milestones for each Research IRD Product Candidate. Revenue Recognition under the Collaboration Agreement The Collaboration Agreement is accounted for under ASC 808, however, ASC 808 does not address recognition or measurement matters. Therefore, the Company will account for the recognition and measurement of consideration under ASC 606. In determining the appropriate amount of revenue to be recognized under ASC 606, the Company performed the following steps: (i) identified the promised goods or services in the contract; (ii) determined whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The Company evaluated the potential performance obligations in the contract, which included the exclusive license to Clinical IRD Product Candidates, the research, development and manufacturing services (“the services”), and the participation in various joint committees and determined that none of the performance obligations by themselves were distinct. Goods and services that are not distinct are bundled with other goods or services in the contract until a bundle of goods or services that is distinct is created. The services, when combined with the licenses, represent a bundle and should be accounted for as a single performance obligation due to the relevance of the services to the value of the early-stage license and the potential for the intellectual property to be significantly modified during the services period. The Company also evaluated whether or not the right to purchase exclusive option rights for specified Research IRD Product Candidates represents future performance obligations and concluded that these represent a separate buyer decision at market rates, rather than a material right performance obligation. As such, these options have been excluded from the initial allocation of transaction price and the Company will account for these options as separate contracts when and if Janssen elects to exercise the options. Under ASC 606, the Company recognized collaboration revenue using the cost-to-cost input method, which it believes best depicts the transfer of control to the customer. Under the cost-to-cost input method, the extent of progress towards completion is measured based on the ratio of actual costs incurred to the total estimated costs expected upon satisfying the combined performance obligation by the potential product candidate. Under this method, revenue is being recorded as a percentage of the estimated transaction price based on the extent of progress towards completion. Under ASC 606, the estimated transaction price includes variable consideration subject to constraints. The Company does not include variable consideration to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will occur when any uncertainty associated with the variable consideration is resolved. The estimate of the Company’s measure of progress and estimate of variable consideration to be included in the transaction price will be updated at each reporting date as a change in estimate. The amount related to the unsatisfied portion will be recognized as that portion is satisfied over time. Under ASC 606 the Company accounts for (i) the licenses it conveyed with respect to the Clinical IRD Product Candidates and (ii) its obligations to perform services as a single performance obligation under the Collaboration Agreement with Janssen on a product candidate basis. Janssen’s right to purchase exclusive options to obtain certain development, manufacturing and commercialization rights are accounted for separately as they do not represent material rights, based on the criteria of ASC 606. Upon the exercise of any purchased option by Janssen, the contract promises associated with an Option Target would use a separate cost-to-cost model for purposes of revenue recognition under ASC 606. In 2019, the Company received a $100.0 million non-refundable upfront fee from Janssen and allocated this amount plus other variable consideration not subject to constraint to each identified performance obligation using a combination of methods allowable under ASC 606. The Company applies the practical expedient in Topic 606 and does not include disclosures regarding amounts for variable consideration allocated to wholly-unsatisfied performance obligations or wholly-unsatisfied distinct goods that form part of a single performance obligation, if any. This variable consideration includes expected reimbursement of research and development costs. During the three-month periods ended September 30, 2021 and 2020, the Company recognized $6.9 million and $5.1 million, respectively, of the deferred revenue – related party as license revenue. During the nine-month periods ended September 30, 2021 and 2020, the Company recognized $16.7 million and $11.8 million, respectively, of the deferred revenue – related party as license revenue. The Company also recognized $16.9 million and $16.2 million during the three-month periods ended September 30, 2021 and 2020, respectively, related to the reimbursement of research and development expenses, which were recorded as an offset to research and development expenses. The Company also recognized $47.1 million and $40.8 million during the nine-month periods ended September 30, 2021 and 2020, respectively, related to the reimbursement of research and development expenses, which were recorded as an offset to research and development expenses. As of September 30, 2021, the Company expects to recognize the remaining $55.5 million in deferred revenue associated with the non-refundable upfront fee over the estimated research and development period using the cost-to-cost input method over an estimated period of approximately 3.75 A summary of the deferred revenue recognition is as follows (in thousands): ​ ​ ​ ​ Deferred revenue at December 31, 2019 $ 86,214 Deferred revenue recognized as license revenue during the year ended December 31, 2020 ​ (15,563) Effects of exchange rate ​ 2,191 Deferred revenue at December 31, 2020 ​ ​ 72,842 Deferred revenue recognized as license revenue during the nine-month period ended September 30, 2021 ​ ​ (16,658) Effects of exchange rate ​ ​ (693) Deferred revenue at September 30, 2021 ​ $ 55,491 ​ Research Agreements The Company is a party to several master services agreements with UCL Consultants Limited, an entity affiliated with University College of London (“UCL”), which is a shareholder of the Company. Pursuant to task orders to the master services agreements, UCL Consultants Limited provides clinical and pre-clinical research and development under the direction of the Company. Total research and development expenses under these agreements for the three-month periods ended September 30, 2021 and 2020 were approximately $0.3 million and $0.3 million, respectively. Total research and development expenses under these agreements for the nine-month periods ended September 30, 2021 and 2020 were approximately $0.7 million and $0.7 million, respectively. Future obligations under the agreements as of September 30, 2021 amounted to $0.4 million. The amount due to UCL under the master services agreements at September 30, 2021 and December 31, 2020 is $0.4 million and $0.3 million, respectively, and is included in accounts payable and accrued expenses on the condensed consolidated balance sheets. License Agreement Effective February 4, 2015, the Company entered into an exclusive worldwide license agreement with UCL Business, PLC (“UCL Business”) to develop up to eight programs using certain ocular gene therapy technology. Under the terms of the agreement, the Company had agreed to pay UCL Business certain sales milestone payments, if achieved, in the aggregate amount of £39.8 million, or approximately $53.6 million using the exchange rate at September 30, 2021, and royalties on net sales, as defined upon commercialization. Additionally, the Company is responsible for all patent prosecution and maintenance costs incurred and has also agreed to pay UCL Business an annual maintenance fee of £0.05 million, or approximately $0.07 million, until the first commercial sale of a product. The agreement terminates upon the later of (i) the last valid claim in a relevant product, (ii) the expiration of regulatory exclusivity to all licensed products, or (iii) the 10 th anniversary of the first commercial sale of a product. On July 28, 2017, March 15, 2018 and September 7, 2018, the Company entered into additional exclusive worldwide license agreements with UCL Business under the same terms as the February 4, 2015 worldwide license agreement. In January and February 2019, the Company amended and restated the following agreements: (i) the License Agreement, dated February 4, 2015, as amended, between the Company and UCL Business; (ii) the License Agreement, dated July 28, 2017, as amended, between the Company and UCL Business; and (iii) the License Agreement, dated March 15, 2018, between the Company and UCL Business to establish new stand-alone license agreements for the following inherited retinal disease programs: (a) achromatopsia (“ACHM”) caused by mutations in CNGB3 CNGA3 RPE65 The Company’s obligation to pay UCL Business a share of certain sublicensing revenues, as was provided under the February 4, 2015 agreement, has been removed from each of the stand-alone agreements with respect to the IRD programs listed above. Each of the stand-alone agreements now reflects terms substantially similar to those of the February 4, 2015 agreement. Additionally, under the new stand-alone agreement related to CNGB3 the Company paid UCL Business an upfront payment of £1.5 million, or approximately $2.0 million, and issued 158,832 of the Company’s ordinary shares, which were valued at £1.5 million, or approximately $2.0 million. Effective March 23, 2020, the Company entered into another worldwide license agreement with UCL Business, to develop an additional ocular gene therapy technology. Under the terms of the agreement, the Company agreed to pay UCL Business certain development and sales milestone payments, if achieved, in the aggregate amount of $39.3 million and royalties on net sales, as defined upon commercialization. Additionally, the Company is responsible for all patent prosecution and maintenance costs incurred and also agreed to pay UCL Business an upfront payment of $0.05 million and an annual maintenance fee of $0.03 million until the first commercial sale of a product. The agreement terminates upon the later of (i) the last valid claim in a relevant product, or (ii) the 10 th anniversary of the first commercial sale of a product. The Company incurred research and development expenses under the agreements in the amount of $0.06 million and $0 during the three-month periods ended September 30, 2021 and 2020, respectively. The Company incurred research and development expenses under the agreements in the amount of $0.4 million and $0.2 million during the nine-month periods ended September 30, 2021 and 2020, respectively. Leases ARE Lease Effective July 1, 2016, the Company entered into a non-cancellable operating lease (the “ARE Lease”) for laboratory and related office facilities in New York with ARE-East River Science Park, LLC (“ARE”). The ARE Lease provided for monthly base rent and property management fees, including rent escalations and rent holidays, plus operating expenses during the lease term, which was scheduled to expire on December 31, 2021. The Company recorded monthly rent expense on a straight-line basis from July 1, 2016 through February 29, 2020, the date the ARE Lease was terminated as described below. On January 28, 2020, the Company and ARE mutually agreed to terminate the lease with no further obligation for either party effective as of February 29, 2020. Accordingly, the remaining right of use asset and operating lease liability in the amount of $0.9 million and $1.0 million, respectively, was written off which resulted in a gain of $0.1 million. The Company did not incur any rent expense under this operating lease for the three-month periods ended September 30, 2021 and 2020. The rent expense under this operating lease was $0 and $0.1 million for the nine-month periods ended September 30, 2021 and 2020, respectively. ARE Vivarium Lease Effective May 1, 2019, the Company entered into an operating lease for vivarium space with ARE, which was subsequently amended to add additional space within the vivarium. The initial lease had a term of twelve months which automatically renews on an annual basis. The rent expense under this operating lease was $0.03 million and $0.01 million for the three-month periods ended September 30, 2021 and 2020, respectively, which are included in loss from operations. The rent expense under this operating lease was $0.05 million and $0.02 million for the nine-month periods ended September 30, 2021 and 2020, respectively, which are included in loss from operations. The Company made cash payments to ARE in connection with this operating lease in the amount of $0.01 million and $0.01 million during the three-month periods ended September 30, 2021 and 2020, respectively. The Company made cash payments to ARE in connection with this operating lease in the amount of $0.05 million and $0.02 million during the nine-month periods ended September 30, 2021 and 2020, respectively. There were no amounts due to ARE under this operating lease at September 30, 2021 and December 31, 2020. Kadmon Lease The Company leases office space on a month-to-month basis from Kadmon Corporation, LLC (“Kadmon”). During the three-month periods ended September, 2021 and 2020, the Company incurred and paid rent charges from Kadmon in the amount of $0.2 million and $0.2 million, respectively, which are included in loss from operations. During the nine-month periods ended September 30, 2021 and 2020, the Company incurred and paid rent charges from Kadmon in the amount of $0.5 and $0.4 million, respectively, which are included in loss from operations. This lease has been terminated effective November 12, 2021.

Leases

Leases	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Leases	9. Leases The Company has commitments under operating leases for laboratory, warehouse and office space, as well as facilities to support clinical trial studies. The Company also has finance leases for manufacturing space and office equipment. The Company’s leases have initial lease terms ranging from 3 years to 191 years. Certain lease agreements contain provisions for future rent increases. Payments due under the lease contracts include fixed payments. Total rent expense under these leases was $1.3 million and $0.8 million for the three-month periods ended September 30, 2021 and 2020, respectively. Total rent expense under these leases was $3.7 million and $2.5 million for the nine-month periods ended September 30, 2021 and 2020, respectively. As of September 30, 2021, the Company has short term lease commitments amounting to approximately $0.01 million on a monthly basis for one lease for vivarium space that is on a one-year lease. On August 4, 2020, Meira Ireland entered into two agreements (the “Agreements”) with Shannon Commercial Enterprises DAC trading as Shannon Commercial Properties, to acquire two properties in the Shannon Free Zone in Shannon, Ireland for an aggregate price of €18 million, or approximately $21.2 million. These properties will serve as the Company’s second cGMP viral vector manufacturing facility and its first cGMP plasmid and DNA production facility. The closing for the first building occurred in August 2020 and the closing for the second building occurred in January 2021. The total cost of the first and second buildings, including taxes and legal fees, was €11.9 million and €7.5 million, or approximately $13.8 million and $8.9 million, respectively, and have been recorded as right of use assets in the condensed consolidated balance sheets as of September 30, 2021. There is no corresponding lease liability as the Company paid the full cost on the date of the closings. At the closings, Meira Ireland entered into a lease for each property providing for a long leasehold interest of approximately 191 years. The leases also include customary terms and conditions, with a nominal annual lease cost and annual maintenance fees of approximately €0.03 million, or approximately $0.04 million, in the aggregate, which is subject to change depending on the annual maintenance costs within the Shannon Free Zone development. During the nine-month period ended September 30, 2021, the Company recognized seven operating leases for locations in connection with its clinical trials for its IRD product candidates with initial lease terms between 5 years and 6 years. Certain lease agreements contain provisions for tenant allowances and future rent increases. Payments due under the lease contracts include fixed payments. In conjunction with these operating leases, the Company recognized initial operating lease right-of-use assets in the amount of $2.2 million and corresponding lease liabilities in the amount of $2.3 million which are included in the right-of-use assets and lease obligations in the condensed consolidated balance sheets as of September 30, 2021. The components of lease cost for the three-month and nine-month periods ended September 30, 2021 and 2020 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Three-month periods ended September 30, ​ ​ 2021 ​ 2020 Finance lease cost ​ ​ Amortization of right-of-use assets ​ $ 305 ​ $ 82 Interest on lease liabilities ​ — ​ 1 Total finance lease cost ​ 305 ​ 83 Operating lease cost ​ 1,293 ​ 830 Short-term lease cost ​ 182 ​ 187 Total lease cost ​ $ 1,780 ​ $ 1,100 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine-month periods ended September 30, ​ ​ 2021 ​ 2020 Finance lease cost ​ ​ ​ Amortization of right-of-use assets ​ $ 927 ​ $ 228 Interest on lease liabilities ​ 1 ​ 2 Total finance lease cost ​ 928 ​ 230 Operating lease cost ​ 3,715 ​ 2,571 Short-term lease cost ​ 640 ​ 527 Total lease cost ​ $ 5,283 ​ $ 3,328 ​ Amounts reported in the condensed consolidated balance sheets for leases where the Company is the lessee as of September 30, 2021 and December 31, 2020 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2021 ​ 2020 ​ Operating leases ​ ​ ​ ​ ​ Right-of-use asset ​ $ 23,581 ​ ​ $ 21,486 ​ Capitalized lease obligations ​ $ 24,525 ​ ​ $ 22,221 ​ Finance leases ​ ​ ​ ​ Right-of-use asset ​ $ 28,429 ​ ​ $ 21,596 ​ Capitalized lease obligations ​ $ 17 ​ ​ $ 28 ​ Weighted-average remaining lease term ​ ​ ​ ​ Operating leases ​ 6.7 years ​ 7.0 years Finance leases ​ 176.9 years ​ 175.1 years Weighted-average discount rate ​ ​ ​ ​ ​ Operating leases ​ 8.5 % ​ 8.6 % Finance leases ​ 8.0 % ​ 8.0 % ​ Other information related to leases for the three-month and nine-month periods ended September 30, 2021 and 2020 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Three-month periods ended September 30, ​ 2021 ​ 2020 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from finance leases $ 4 ​ $ 4 Operating cash flows from operating leases $ 1,234 ​ $ 970 Financing cash flows from finance leases $ — ​ $ 1 ​ ​ ​ ​ ​ ​ Right-of-use assets obtained in exchange for lease liabilities ​ ​ ​ Operating leases $ — ​ $ — Finance leases $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ Nine-month periods ended September 30, ​ 2021 ​ 2020 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from finance leases $ 12 ​ $ 17 Operating cash flows from operating leases $ 3,678 ​ $ 2,512 Financing cash flows from finance leases $ 1 ​ $ 2 ​ ​ ​ ​ ​ ​ Right-of-use assets obtained in exchange for lease liabilities ​ ​ ​ Operating leases $ 4,424 ​ $ — Finance leases $ — ​ $ — ​ Future minimum lease payments under non-cancellable leases as of September 30, 2021 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating Leases Finance Leases 2021 ​ $ 1,292 ​ $ 4 2022 ​ ​ 5,250 ​ ​ 14 2023 ​ 5,380 ​ — 2024 ​ 5,221 ​ — 2025 ​ 5,225 ​ — Thereafter ​ 9,265 ​ — Total undiscounted lease payments ​ $ 31,633 ​ $ 18 Less: Imputed interest ​ (7,108) ​ (1) Total lease liabilities ​ $ 24,525 ​ $ 17 ​

Commitments

Commitments	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments	10. Commitments There were no new material commitments entered into during the nine-month period ended September 30, 2021. ​

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Event	11. Subsequent Event Management has evaluated subsequent events through the date of this filing. Based on its evaluation, there were no subsequent events to report.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Consolidation	Consolidation The accompanying condensed consolidated financial statements include the accounts of Meira Holdings and its wholly owned subsidiaries: MeiraGTx Limited, a limited company incorporated under the laws of England and Wales; MeiraGTx, LLC, a Delaware limited liability company (“Meira LLC”); MeiraGTx UK II Limited, a limited company incorporated under the laws of England and Wales (“Meira UK II”); MeiraGTx Ireland DAC, a designated activity company incorporated under the laws of Ireland (“Meira Ireland”); MeiraGTx Netherlands, B.V., a private company with limited liability incorporated under the laws of the Netherlands (“Meira Netherlands”); MeiraGTx Belgium, a private company with limited liability incorporated under the laws of Belgium (“Meira Belgium”); BRI-Alzan, Inc., a Delaware corporation (“BRI-Alzan”); MeiraGTx Bio, Inc., a Delaware corporation (“Meira Bio”); MeiraGTx B.V., a private company with limited liability incorporated under the laws of the Netherlands (“Meira B.V.”); MeiraGTx Neurosciences, Inc., a Delaware corporation (“Meira Neuro”); and MeiraGTx UK Limited, a limited company incorporated under the laws of England and Wales (“Meira UK”). All intercompany balances and transactions between the consolidated companies have been eliminated in consolidation.
Use of Estimates	Use of Estimates Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these condensed consolidated financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. This process may result in actual results differing materially from those estimated amounts used in the preparation of the financial statements if these results differ from historical experience, or other assumptions do not turn out to be substantially accurate, even if such assumptions are reasonable when made. In preparing these condensed consolidated financial statements, management used significant estimates in the following areas, among others: collaboration revenue, the accounting for research and development costs, share-based compensation, leases, asset retirement obligations and tax incentive receivable. Additionally, the Company has made estimates of the impact of the COVID-19 pandemic within the condensed consolidated financial statements and there may be changes to those estimates in future periods. Actual results may differ from these estimates.
Fair Value Measurements	Fair Value Measurements Fair value is defined as the price that would be received upon sale of an asset or paid upon transfer of a liability in an orderly transaction between market participants at the measurement date and in the principal or most advantageous market for that asset or liability. The fair value should be calculated based on assumptions that market participants would use in pricing the asset or liability, not on assumptions specific to the entity. In addition, the fair value of liabilities should include consideration of non-performance risk including the Company’s credit risk. The Company follows ASC Topic 820, Fair Value Measurements and Disclosures around fair value and establishes a fair value hierarchy for valuation inputs. The hierarchy prioritizes the inputs into three levels based on the extent to which inputs used in measuring fair value are observable in the market. Each fair value measurement is reported in one of the three levels which are determined by the lowest level input that is significant to the fair value measurement in its entirety. These levels are: ● Level 1: Observable inputs such as quoted prices in active markets for identical assets the reporting entity has the ability to access as of the measurement date; ● Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly; and ● Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.
Equity Method and Other Investments	Equity Method and Other Investments The Company accounts for equity investments under the equity method of accounting when the requirements for consolidation are not met, and the Company has significant influence over the operations of the investee. Equity method investments are initially recorded at cost and subsequently adjusted for the Company’s share of net income or loss and cash contributions and distributions and are included in equity method and other investments in the accompanying condensed consolidated balance sheets. Equity investments that do not result in consolidation and are not accounted for under the equity method are measured at fair value, with any changes in fair value recognized in net income (loss). For any such investments that do not have readily determinable fair values, the Company elects the measurement alternative to measure the investments at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Equity method investments are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. If it is determined that a loss in value of the equity method investment is other than temporary, an impairment loss is measured based on the excess of the carrying amount of an investment over its estimated fair value. Impairment analyses are based on current plans, intended holding periods, and available information at the time the analysis is prepared.
Leases	Leases The Company accounts for leases in accordance with ASC 842. The Company determines if an arrangement is a lease at contract inception. A lease exists when a contract conveys the right to control the use of identified property, plant, or equipment for a period of time in exchange for consideration. The definition of a lease embodies two conditions: (1) there is an identified asset in the contract that is land or a depreciable asset (i.e., property, plant, and equipment), and (2) the Company has the right to control the use of the identified asset. The Company accounts for the lease and non-lease components as a single lease component. From time to time the Company enters into direct financing lease arrangements that include a lessee obligation to purchase the leased asset at the end of the lease term, a bargain purchase option, or provides for minimum lease payments with a present value of 90% or more of the fair value of the leased asset at the date of lease inception. Operating leases where the Company is the lessee are included in right-of-use (“ROU”) assets and lease obligations are included on the Company’s consolidated balance sheets. The lease obligations are initially and subsequently measured at the present value of the unpaid lease payments at the lease commencement date and subsequent reporting periods. Finance leases where the Company is the lessee are included in ROU assets and lease obligations on the Company’s consolidated balance sheets. The lease obligations are initially measured in the same manner as for operating leases and are subsequently measured at amortized cost using the effective interest method. Key estimates and judgments include how the Company determined (1) the discount rate used to discount the unpaid lease payments to present value, (2) lease term and (3) lease payments. ASC 842 requires a lessee to discount its unpaid lease payments using the interest rate implicit in the lease or, if that rate cannot be readily determined, its incremental borrowing rate. As most of the Company’s leases where it is the lessee do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The Company’s incremental borrowing rate for a lease is the rate of interest it would have to pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. The Company uses the implicit rate when readily determinable. The lease term for all of the Company’s leases includes the non-cancellable period of the lease plus any additional periods covered by either a lessee option to extend (or not to terminate) the lease that is reasonably certain to be exercised, or an option to extend (or not to terminate) the lease controlled by the lessor. The ROU asset is initially measured at cost, which comprises the initial amount of the lease liability adjusted for lease payments made at or before the lease commencement date less any lease incentives received. For operating leases, the ROU asset is subsequently measured throughout the lease term at the carrying amount of the lease liability, minus any accrued lease payments, less the unamortized balance of lease incentives received. Lease expense for lease payments is recognized on a straight-line basis over the lease term. For finance leases, the ROU asset is subsequently amortized using the straight-line method from the lease commencement date to the earlier of the end of its useful life or the end of the lease term unless the lease transfers ownership of the underlying asset, or the Company is reasonably certain to exercise an option to purchase the underlying asset. In those cases, the ROU asset is amortized over the useful life of the underlying asset. Amortization of the ROU asset is recognized and presented separately from interest expense on the lease liability. The Company has elected not to recognize ROU assets and lease liabilities for all short-term leases that have a lease term of 12 months or less at lease commencement. Lease payments associated with short-term leases are recognized as an expense on a straight-line basis over the lease term.
Asset Retirement Obligations	Asset Retirement Obligations Accounting for asset retirement obligations requires legal obligations associated with the retirement of long-lived assets to be recognized at fair value when incurred and capitalized as part of the related long-lived asset. In the absence of quoted market prices, the Company estimates the fair value of its asset retirement obligations using Level 3 present value techniques, in which estimates of future cash flows associated with retirement activities are discounted using a credit-adjusted risk-free rate. Asset retirement obligations currently reported as other liabilities on the condensed consolidated balance sheet were measured during a period of historically low interest rates. The impact on measurements of new asset retirement obligations using different rates in the future may be significant. The Company uses estimates to determine the asset retirement obligations at the end of the lease term and discounts such asset retirement obligations using an estimated discount rate. Interest on the discounted asset retirement obligation is amortized over the term of the lease using the effective interest method and is recorded as interest expense in the condensed consolidated statements of operations and comprehensive loss. The change in asset retirement obligations is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Nine-Month Periods Ended September 30, ​ ​ 2021 ​ 2020 Balance at beginning of period $ 1,814 $ 1,655 Amortization of interest ​ 112 ​ 101 Effects of exchange rate ​ (10) ​ (14) Balance at end of period ​ $ 1,916 ​ $ 1,742
Collaboration Arrangements	Collaboration Arrangements The Company evaluates its collaborative arrangements pursuant to ASC 808, Collaborative Arrangements Revenue from Contracts with Customers ASC 808 does not address recognition or measurement matters related to collaborative arrangements. Payments between participants pursuant to a collaborative arrangement that are within the scope of other authoritative accounting literature on income statement classification are accounted for using the relevant provisions of that literature. If the payments are not within the scope of other authoritative accounting literature, the income statement classification for the payments is based on an analogy to authoritative accounting literature or if there is no appropriate analogy, a reasonable, rational and consistently applied accounting policy election. Payments received from a collaboration partner to which this policy applies may include upfront payments in respect of a license of intellectual property, development and commercialization-based milestones, and royalties. Refer to the discussion in Note 8 for further information related to the accounting for the Collaboration Agreement.
Revenue Recognition	Revenue Recognition Arrangements with collaborators may include licenses to intellectual property, research and development services, manufacturing services for clinical and commercial supply, and participation on joint steering committees. The Company evaluates the promised goods or services to determine which promises, or group of promises, represent performance obligations. In contemplation of whether a promised good or service meets the criteria required of a performance obligation, the Company considers the stage of development of the underlying intellectual property, the capabilities and expertise of the customer relative to the underlying intellectual property, and whether the promised goods or services are integral to or dependent on other promises in the contract. When accounting for an arrangement that contains multiple performance obligations, the Company must develop judgmental assumptions, which may include market conditions, reimbursement rates for personnel costs, development timelines and probabilities of regulatory success to determine the stand-alone selling price for each performance obligation identified in the contract. When the Company concludes that a contract should be accounted for as a combined performance obligation and recognized over time, the Company must then determine the period over which revenue should be recognized and the method by which to measure revenue. The Company generally recognizes revenue using a cost-based input method. The Collaboration Agreement with Janssen is accounted for under ASC 808, however, as ASC 808 does not address recognition or measurement matters such as determining the appropriate unit of accounting or when the recognition criteria are met, the Company accounts for the consideration received from Janssen in accordance with ASC 606. In accordance with ASC 606, the Company recognizes revenue when its customer or collaborator obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, it performs the following five steps: i. identify the contract(s) with a customer; ii. identify the performance obligations in the contract; iii. determine the transaction price; iv. allocate the transaction price to the performance obligations within the contract; and v. recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it determines that it is probable it will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be by analogy within the scope of ASC 606, the Company assesses the goods or services promised within the contract to determine whether each promised good or service is a performance obligation. The promised goods or services in the Company’s arrangements typically consist of a license to the Company’s intellectual property and research, development and manufacturing services. The Company may provide options to additional items in such arrangements, which are accounted for as separate contracts when the customer elects to exercise such options, unless the option provides a material right to the customer. Performance obligations are promises in a contract to transfer a distinct good or service to the customer that (i) the customer can benefit from on its own or together with other readily available resources, and (ii) is separately identifiable from other promises in the contract. Goods or services that are not individually distinct performance obligations are combined with other promised goods or services until such combined group of promises meet the requirements of a performance obligation. The Company determines transaction price based on the amount of consideration the Company expects to receive for transferring the promised goods or services in the contract. Consideration may be fixed, variable, or a combination of both. At contract inception for arrangements that include variable consideration, the Company estimates the probability and extent of consideration it expects to receive under the contract utilizing either the most likely amount method or expected amount method, whichever best estimates the amount expected to be received. The Company then considers any constraints on the variable consideration and includes in the transaction price variable consideration to the extent it is deemed probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. The Company then allocates the transaction price to each performance obligation based on the relative standalone selling price and recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) control is transferred to the customer and the performance obligation is satisfied. For performance obligations which consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The Company records amounts as accounts receivable when the right to consideration is deemed unconditional. When consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract, a contract liability is recorded as deferred revenue. Amounts received prior to satisfying the revenue recognition criteria are recognized as deferred revenue in the Company’s condensed consolidated balance sheet. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue – related party, current. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue – related party. The Company’s collaboration revenue arrangements include the following: Up-front License Fees: If a license is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from nonrefundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments: At the inception of an agreement that includes research and development milestone payments, the Company evaluates each milestone to determine when and how much of the milestone to include in the transaction price. The Company first estimates the amount of the milestone payment that the Company could receive using either the expected value or the most likely amount approach. The Company primarily uses the most likely amount approach as that approach is generally most predictive for milestone payments with a binary outcome. Then, the Company considers whether any portion of that estimated amount is subject to the variable consideration constraint (that is, whether it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty.) The Company updates the estimate of variable consideration included in the transaction price at each reporting date which includes updating the assessment of the likely amount of consideration and the application of the constraint to reflect current facts and circumstances. Royalties: For arrangements that include sales-based royalties, including milestone payments based on a level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any revenue related to sales-based royalties or milestone payments based on the level of sales. Research and Development Services: The Company is incurring research and development costs, with Janssen responsible for up to 100% of the costs, depending on the type of research and development services being performed. The Company records costs associated with the development activities as research and development expenses in the condensed consolidated statements of operations and comprehensive loss consistent with ASC 730, Research and Development
Research and Development	Research and Development Research and development costs are charged to expense as incurred. These costs include, but are not limited to, employee-related expenses, including salaries, benefits and travel of the Company’s research and development personnel; expenses incurred under agreements with contract research organizations and investigative sites that conduct clinical and preclinical studies and for the drug product for the clinical studies and preclinical activities; facilities; supplies; rent, insurance, certain legal fees, share-based compensation, depreciation and other costs associated with clinical and preclinical activities and regulatory operations. Research funding under collaboration agreements and refundable research and development credits / tax credits are recorded as an offset to these costs. Costs for certain development activities, such as Company funded outside research programs, are recognized based on an evaluation of the progress to completion of specific tasks with respect to their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the condensed consolidated financial statements as prepaid expenses or accrued expenses, as the case may be.
Net Loss per Ordinary Share	Net Loss per Ordinary Share Basic net loss per ordinary share is computed by dividing net loss by the weighted average number of shares of the Company’s ordinary shares assumed to be outstanding during the period of computation. Diluted net loss per ordinary share is computed similar to basic net loss per share except that the denominator is increased to include the number of additional ordinary shares that would have been outstanding if the potential ordinary shares had been issued at the beginning of the year and if the additional ordinary shares were dilutive (treasury stock method) or the two-class method, whichever is more dilutive. For all periods presented, basic and diluted net loss per ordinary share are the same, as any additional ordinary share equivalents would be anti-dilutive. The following securities are considered to be ordinary share equivalents, but were not included in the computation of diluted net loss per ordinary share because to do so would have been anti-dilutive: ​ ​ ​ ​ ​ ​ ​ September 30, September 30, ​ 2021 2020 Share options 6,141,510 4,970,531 Restricted share units ​ 1,415,000 ​ 545,000 Restricted ordinary shares subject to forfeiture ​ 145,000 ​ — ​ 7,701,510 5,515,531 ​
Segment Information	Segment Information Management has concluded it has a single reporting segment for purposes of reporting financial condition and results of operations. The Company’s license revenue, research funding and deferred revenue from its Collaboration Agreement are generated in the United Kingdom. The following table summarizes non-current assets by geographical area (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2021 ​ 2020 United States ​ $ 23,947 ​ $ 17,536 United Kingdom ​ 43,728 ​ 44,487 European Union ​ ​ 58,730 ​ ​ 29,098 ​ ​ $ 126,405 ​ $ 91,121 ​
Recent Accounting Pronouncements Not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments

Summary of Significant Accoun_3

Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Tables)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Schedule of Change in Asset Retirement Obligations	The change in asset retirement obligations is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Nine-Month Periods Ended September 30, ​ ​ 2021 ​ 2020 Balance at beginning of period $ 1,814 $ 1,655 Amortization of interest ​ 112 ​ 101 Effects of exchange rate ​ (10) ​ (14) Balance at end of period ​ $ 1,916 ​ $ 1,742
Schedule of Anti-dilutive Securities Excluded from Computation of Earnings per Share	​ ​ ​ ​ ​ ​ ​ September 30, September 30, ​ 2021 2020 Share options 6,141,510 4,970,531 Restricted share units ​ 1,415,000 ​ 545,000 Restricted ordinary shares subject to forfeiture ​ 145,000 ​ — ​ 7,701,510 5,515,531
Summary of Non-Current Assets by Geographical Area	The following table summarizes non-current assets by geographical area (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2021 ​ 2020 United States ​ $ 23,947 ​ $ 17,536 United Kingdom ​ 43,728 ​ 44,487 European Union ​ ​ 58,730 ​ ​ 29,098 ​ ​ $ 126,405 ​ $ 91,121

Equity Method and Other Inves_2

Equity Method and Other Investments (Tables)	9 Months Ended
	Sep. 30, 2021
Long-term Investments [Abstract]
Schedule of investments	The Company’s investments consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2021 Investee Investment Type Ownership Percentage Carrying Value Cost Basis Visiogene LLC ​ Equity Method Investment ​ 25 % ​ $ 5,165 ​ $ 5,165 Other ​ Equity Investment ​ 3 % ​ ​ 1,500 ​ ​ 1,500 Total equity method and other investments ​ ​ ​ ​ ​ ​ $ 6,665 ​ $ 6,665

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2021
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses for the periods presented are comprised of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2021 ​ 2020 Clinical trial costs ​ $ 11,509 ​ $ 10,261 Fixed assets ​ 3,107 ​ 949 Manufacturing costs ​ 2,923 ​ 1,886 Research and development ​ 1,813 ​ 893 Compensation and benefits ​ ​ 1,371 ​ ​ 3,791 Professional fees ​ 548 ​ 1,219 Consulting ​ 327 ​ 1,047 Other ​ ​ 328 ​ 815 ​ ​ $ 21,926 ​ $ 20,861

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Company's Share Option Activity Related to Employees, Non-Employee Members of the Board of Directors and Non-Employee Consultants	A summary of the Company’s share option activity related to employees, non-employee members of the board of directors and non-employee consultants as of December 31, 2020 and for the nine-month period ended September 30, 2021 is as follows (in thousands, except share and per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ Weighted- ​ Average ​ ​ ​ ​ ​ ​ Average ​ ​ Remaining ​ ​ ​ ​ Number of ​ Exercise ​ ​ Contractual ​ ​ ​ ​ Options ​ Price ​ ​ Life (years) ​ Outstanding at December 31, 2020 ​ 4,824,771 ​ $ 11.85 ​ 7.67 years Granted ​ 1,628,700 ​ $ 15.66 ​ ​ ​ Exercised ​ (52,235) ​ $ 7.92 ​ ​ ​ Expired ​ ​ (98,025) ​ $ 9.03 ​ ​ ​ ​ Forfeited ​ (161,701) ​ $ 15.19 ​ ​ ​ Outstanding at September 30, 2021 ​ 6,141,510 ​ $ 12.99 ​ ​ 7.60 years Options exercisable at September 30, 2021 ​ 3,272,190 ​ $ 10.69 ​ 6.68 years Aggregate intrinsic value of options outstanding as of September 30, 2021 ​ $ 14,914 ​ ​ ​ Aggregate intrinsic value of options exercisable as of September 30, 2021 ​ $ 13,090 ​ ​ ​
Schedule of Grant Date Fair Values of the Stock Options Granted	​ ​ ​ ​ ​ ​ ​ 2021 2020 Risk-free interest rate 0.62 - 1.14% 0.32 - 2.56% Expected volatility 90% 90% Expected dividend yield 0% 0% Expected life (in years) 5.5 - 6.1 5.5 - 6.1
Summary of Company's RSU Activity Related to Employees, Non-Employee Members of the Board of Directors and Non-Employee Consultants	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ Number of ​ Average ​ ​ ​ Restricted ​ Grant Date ​ ​ ​ Share Units ​ Fair Value Outstanding at December 31, 2020 ​ 545,000 ​ $ 20.02 Granted ​ 870,000 ​ $ 15.36 Vested ​ ​ — ​ $ — Forfeited ​ — ​ $ — Outstanding at September 30, 2021 ​ 1,415,000 ​ $ 17.16
Schedule of Share-Based Compensation Expense	During the three-month and nine-month periods ended September 30, 2021 and 2020 the Company recognized total share-based compensation expense in the accompanying condensed consolidated statements of operations and comprehensive loss as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three-month periods ended September 30, ​ 2021 2020 Research and development ​ $ 2,436 ​ $ 1,560 General and administrative ​ 2,903 ​ 2,178 Total share-based compensation ​ $ 5,339 ​ $ 3,738 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine-month periods ended September 30, ​ 2021 2020 Research and development ​ $ 7,273 ​ $ 4,442 General and administrative ​ 8,086 ​ ​ 10,035 Total share-based compensation ​ $ 15,359 ​ $ 14,477

Related-Party Transactions (Tab

Related-Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Summary of the Deferred Revenue Recognition	A summary of the deferred revenue recognition is as follows (in thousands): ​ ​ ​ ​ Deferred revenue at December 31, 2019 $ 86,214 Deferred revenue recognized as license revenue during the year ended December 31, 2020 ​ (15,563) Effects of exchange rate ​ 2,191 Deferred revenue at December 31, 2020 ​ ​ 72,842 Deferred revenue recognized as license revenue during the nine-month period ended September 30, 2021 ​ ​ (16,658) Effects of exchange rate ​ ​ (693) Deferred revenue at September 30, 2021 ​ $ 55,491

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Schedule of Components of Lease Cost	The components of lease cost for the three-month and nine-month periods ended September 30, 2021 and 2020 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Three-month periods ended September 30, ​ ​ 2021 ​ 2020 Finance lease cost ​ ​ Amortization of right-of-use assets ​ $ 305 ​ $ 82 Interest on lease liabilities ​ — ​ 1 Total finance lease cost ​ 305 ​ 83 Operating lease cost ​ 1,293 ​ 830 Short-term lease cost ​ 182 ​ 187 Total lease cost ​ $ 1,780 ​ $ 1,100 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine-month periods ended September 30, ​ ​ 2021 ​ 2020 Finance lease cost ​ ​ ​ Amortization of right-of-use assets ​ $ 927 ​ $ 228 Interest on lease liabilities ​ 1 ​ 2 Total finance lease cost ​ 928 ​ 230 Operating lease cost ​ 3,715 ​ 2,571 Short-term lease cost ​ 640 ​ 527 Total lease cost ​ $ 5,283 ​ $ 3,328
Schedule of Consolidated Balance Sheets for Leases	Amounts reported in the condensed consolidated balance sheets for leases where the Company is the lessee as of September 30, 2021 and December 31, 2020 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, December 31, ​ ​ 2021 ​ 2020 ​ Operating leases ​ ​ ​ ​ ​ Right-of-use asset ​ $ 23,581 ​ ​ $ 21,486 ​ Capitalized lease obligations ​ $ 24,525 ​ ​ $ 22,221 ​ Finance leases ​ ​ ​ ​ Right-of-use asset ​ $ 28,429 ​ ​ $ 21,596 ​ Capitalized lease obligations ​ $ 17 ​ ​ $ 28 ​ Weighted-average remaining lease term ​ ​ ​ ​ Operating leases ​ 6.7 years ​ 7.0 years Finance leases ​ 176.9 years ​ 175.1 years Weighted-average discount rate ​ ​ ​ ​ ​ Operating leases ​ 8.5 % ​ 8.6 % Finance leases ​ 8.0 % ​ 8.0 %
Schedule of Other Information Related to Leases	Other information related to leases for the three-month and nine-month periods ended September 30, 2021 and 2020 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Three-month periods ended September 30, ​ 2021 ​ 2020 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from finance leases $ 4 ​ $ 4 Operating cash flows from operating leases $ 1,234 ​ $ 970 Financing cash flows from finance leases $ — ​ $ 1 ​ ​ ​ ​ ​ ​ Right-of-use assets obtained in exchange for lease liabilities ​ ​ ​ Operating leases $ — ​ $ — Finance leases $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ Nine-month periods ended September 30, ​ 2021 ​ 2020 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from finance leases $ 12 ​ $ 17 Operating cash flows from operating leases $ 3,678 ​ $ 2,512 Financing cash flows from finance leases $ 1 ​ $ 2 ​ ​ ​ ​ ​ ​ Right-of-use assets obtained in exchange for lease liabilities ​ ​ ​ Operating leases $ 4,424 ​ $ — Finance leases $ — ​ $ —
Schedule of Future Minimum Lease Payments Under Non-Cancellable Leases	Future minimum lease payments under non-cancellable leases as of September 30, 2021 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating Leases Finance Leases 2021 ​ $ 1,292 ​ $ 4 2022 ​ ​ 5,250 ​ ​ 14 2023 ​ 5,380 ​ — 2024 ​ 5,221 ​ — 2025 ​ 5,225 ​ — Thereafter ​ 9,265 ​ — Total undiscounted lease payments ​ $ 31,633 ​ $ 18 Less: Imputed interest ​ (7,108) ​ (1) Total lease liabilities ​ $ 24,525 ​ $ 17

Organization and Basis of Pre_2

Organization and Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Description Of Business [Line Items]
Accumulated deficit	$ (330,677)		$ (261,028)
Cash flows from operations	(29,358)	$ (34,405)
Cash, cash equivalents and restricted cash	$ 143,634	$ 179,335	$ 209,520	$ 227,357
Minimum
Schedule Of Description Of Business [Line Items]
Offsetting expense, period	12 months

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Schedule of Change in Asset Retirement Obligations (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Asset Retirement Obligation [Abstract]
Balance at beginning of period	$ 1,814	$ 1,655
Amortization of interest	112	101
Effects of exchange rate	(10)	(14)
Balance at end of period	$ 1,916	$ 1,742

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Anti-dilutive Securities Excluded from Computation of Earnings per Share (Details) - shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earning per share, amount	7,701,510	5,515,531
Share Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earning per share, amount	6,141,510	4,970,531
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earning per share, amount	1,415,000	545,000
Restricted Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earning per share, amount	145,000

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Summary of Non-Current Assets by Geographical Area (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Operation By Geographical [Line Items]
Non-current assets	$ 126,405	$ 91,121
United States
Operation By Geographical [Line Items]
Non-current assets	23,947	17,536
United Kingdom
Operation By Geographical [Line Items]
Non-current assets	43,728	44,487
European Union
Operation By Geographical [Line Items]
Non-current assets	$ 58,730	$ 29,098

Equity Method and Other Inves_3

Equity Method and Other Investments - Summary of Investments (Details) $ in Thousands	Sep. 30, 2021USD ($)
Schedule of Equity Method Investments [Line Items]
Ownership Percentage, other investments	3.00%
Carrying Value and cost other investments	$ 1,500
Total equity method and other investments	$ 6,665
Visiogene LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage	25.00%
Carrying Value	$ 5,165
Cost Basis	$ 5,165

Equity Method and Other Inves_4

Equity Method and Other Investments (Details) - USD ($) $ in Thousands	Jan. 04, 2021	Mar. 31, 2021
Visiogene License Agreement
Schedule of Equity Method Investments [Line Items]
Ordinary shares issued in connection with a license agreement (in shares)	75,000
Value of shares issued	$ 1,200	$ 1,165
Visiogene LLC
Schedule of Equity Method Investments [Line Items]
Number of preferred units acquired	3,000,000
Cash consideration	$ 5,000
Ordinary shares issued in connection with a license agreement (in shares)	75,000
Value of shares issued	$ 1,200
Visiogene LLC | Visiogene License Agreement
Schedule of Equity Method Investments [Line Items]
Allocation of payments	1,000
Investment allocated amount expensed	1,000
Visiogene LLC | Visiogene Unit Agreement
Schedule of Equity Method Investments [Line Items]
Allocation of payments	$ 5,200

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Clinical trial costs	$ 11,509	$ 10,261
Fixed assets	3,107	949
Manufacturing costs	2,923	1,886
Research and development	1,813	893
Compensation and benefits	1,371	3,791
Professional fees	548	1,219
Consulting	327	1,047
Other	328	815
Accrued expenses	$ 21,926	$ 20,861

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details)	Jun. 07, 2018item$ / sharesshares	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)$ / shares	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average remaining contractual life of options, outstanding				7 years 7 months 6 days		7 years 8 months 1 day
Fair value of options, Vested		$ 2,500,000	$ 1,300,000	$ 12,200,000	$ 6,800,000
Weighted-average grant date fair value of options granted | $ / shares				$ 11.54	$ 12.73
Share-based compensation				$ 15,359,000	$ 14,477,000
Total share-based compensation		5,339,000	3,738,000	15,359,000	14,477,000
Excess tax benefits, operating activities				0	0
Excess tax benefits, financing activities				$ 0	0
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average remaining contractual life of options, outstanding				10 years
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation		2,903,000	2,178,000	$ 8,086,000	10,035,000
Research and Development Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation		2,436,000	1,560,000	$ 7,273,000	4,442,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period expected to realize unrecognized compensation expense				4 years
Total compensation expense not yet recognized relating to unvested RSUs		17,500,000		$ 17,500,000
Ordinary shares | shares				870,000
Total share-based compensation		1,700,000	700,000	$ 4,100,000	2,000,000
Restricted Stock Units (RSUs) | General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation		1,500,000	600,000	3,500,000	1,900,000
Restricted Stock Units (RSUs) | Research and Development Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation		200,000	100,000	600,000	100,000
Share Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unvested options compensation expense not yet recognized		29,500,000		$ 29,500,000
Period expected to realize unrecognized compensation expense				4 years
Total share-based compensation		3,600,000	3,000,000	$ 11,300,000	9,600,000
Share Options | General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation		1,400,000	1,500,000	4,600,000	5,300,000
Share Options | Research and Development Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation		$ 2,200,000	$ 1,500,000	$ 6,700,000	4,300,000
Senior Management [Member] | Restricted Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	33.33%
Ordinary shares awarded, per share | $ / shares	$ 15
Ordinary shares | shares	1,306,348
Fully-diluted outstanding shares	5.00%
Number of quarters for vesting | item	8
Share-based compensation					6,500,000
Total share-based compensation					2,900,000
Senior Management [Member] | Restricted Shares | General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation					$ 3,600,000
Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				36 months
First Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				25.00%
Second Anniversary [Member] | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				50.00%
Third Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				25.00%
Fourth Anniversary [Member] | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				25.00%
Over Three Years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				36 months

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Company's Share Option Activity (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2020$ / sharesshares
Number of Options
Number of options, Beginning balance | shares	4,824,771
Number of options, Granted | shares	1,628,700
Number of options, Exercised | shares	(52,235)
Number of options, Expired | shares	(98,025)
Number of options, Forfeited | shares	(161,701)
Number of options, Ending balance | shares	6,141,510	4,824,771
Weighted-Average Exercise Price
Weighted-average exercise price, Beginning balance | $ / shares	$ 11.85
Weighted-average exercise price, Granted | $ / shares	15.66
Weighted-average exercise price, Exercised | $ / shares	7.92
Weighted-average exercise price, Expired | $ / shares	9.03
Weighted-average exercise price, Forfeited | $ / shares	15.19
Weighted-average exercise price, Ending balance | $ / shares	$ 12.99	$ 11.85
Options additional disclosures
Number of options, Options exercisable | shares	3,272,190
Weighted-average exercise price, Option exercisable | $ / shares	$ 10.69
Weighted-average remaining contractual life of options, outstanding	7 years 7 months 6 days	7 years 8 months 1 day
Weighted-average remaining contractual life of options, exercisable	6 years 8 months 4 days
Aggregate intrinsic value, options outstanding | $	$ 14,914
Aggregate intrinsic value, options exercisable | $	$ 13,090

Share-Based Compensation - Sche

Share-Based Compensation - Schedule of Grant Date Fair Values of the Share Options Granted Black-Scholes Valuation Model (Details) - Share Options	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, minimum	0.62%	0.32%
Risk-free interest rate, maximum	1.14%	2.56%
Expected volatility	90.00%	90.00%
Expected dividend yield	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	5 years 6 months	5 years 6 months
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	6 years 1 month 6 days	6 years 1 month 6 days

Share-Based Compensation - Su_2

Share-Based Compensation - Summary of Restricted Share Units (Details) - Restricted Stock Units (RSUs)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Number of restricted share units
Number of restricted share units, Beginning balance | shares	545,000
Number of restricted share units, Granted | shares	870,000
Number of restricted share units, Ending balance | shares	1,415,000
Weighted-average grant date fair value
Weighted-average grant date fair value, Beginning balance | $ / shares	$ 20.02
Weighted-average grant date fair value, Granted | $ / shares	15.36
Weighted-average grant date fair value, Ending balance | $ / shares	$ 17.16

Share-Based Compensation - Sc_2

Share-Based Compensation - Schedule of Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Based Compensation Expense [Line Items]
Total share-based compensation	$ 5,339	$ 3,738	$ 15,359	$ 14,477
General and Administrative Expense [Member]
Share Based Compensation Expense [Line Items]
Total share-based compensation	2,903	2,178	8,086	10,035
Research and Development Expenses [Member]
Share Based Compensation Expense [Line Items]
Total share-based compensation	$ 2,436	$ 1,560	$ 7,273	$ 4,442

Ordinary Shares - Additional In

Ordinary Shares - Additional Information (Details) - Visiogene License Agreement - USD ($) $ in Thousands	Jan. 04, 2021	Mar. 31, 2021
Ordinary shares issued in connection with a license agreement (in shares)	75,000
Issuance of shares in connection with a license agreement	$ 1,200	$ 1,165

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 0	$ 0	$ 0	$ 0

Related-Party Transactions - Co

Related-Party Transactions - Collaboration and License Agreements (Details) - USD ($) $ in Thousands	Jan. 30, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Feb. 27, 2019
Related Party Transaction [Line Items]
Shares issued to related party		44,316,385		44,316,385		44,189,150
Clinical IRD Product Candidate development | Maximum
Related Party Transaction [Line Items]
Additional development and commercialization milestones	$ 340,000
Clinical IRD Product Candidate development | Collaboration Agreement
Related Party Transaction [Line Items]
Royalties receivable, as a percentage	20.00%
JJDC | Private Placement [Member]
Related Party Transaction [Line Items]
Shares issued to related party								2,898,550
Janssen Pharmaceuticals Inc | Collaboration Agreement
Related Party Transaction [Line Items]
Collaboration agreement upfront payment							$ 100,000
Deferred revenue - related party recognized as license revenue		$ 6,900	$ 5,100	$ 16,658	$ 11,800	$ 15,563
Reimbursement of research and development expenses		16,900	$ 16,200	47,100	$ 40,800
Revenue, remaining performance obligation, amount		$ 55,500		$ 55,500
Estimated period to recognize remaining deferred revenue				3 years 9 months
Janssen Pharmaceuticals Inc | Research, development and commercialization of gene therapies | Collaboration Agreement
Related Party Transaction [Line Items]
Collaboration agreement upfront payment	$ 100,000
Janssen Pharmaceuticals Inc | Clinical IRD Product Candidate development | Collaboration Agreement
Related Party Transaction [Line Items]
Percentage of clinical and commercialization costs to be paid by related party	100.00%
Janssen Pharmaceuticals Inc | Research IRD Candidates development | Collaboration Agreement
Related Party Transaction [Line Items]
Percentage of clinical and commercialization costs to be paid by related party	100.00%

Related-Party Transactions - Re

Related-Party Transactions - Revenue Recognition (Details) - Janssen Pharmaceuticals Inc - Collaboration Agreement - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Related Party Transaction [Line Items]
Deferred revenue at the beginning			$ 72,842	$ 86,214	$ 86,214
Deferred revenue recognized as license revenue during period	$ (6,900)	$ (5,100)	(16,658)	$ (11,800)	(15,563)
Effects of exchange rate			(693)		2,191
Deferred revenue at the end	$ 55,491		$ 55,491		$ 72,842

Related-Party Transactions - _2

Related-Party Transactions - Research Agreements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Related Party Transaction [Line Items]
Research and development expenses	$ 21,612	$ 4,626	$ 53,512	$ 28,911
UCL Consultants Limited | Master Services Agreement [Member]
Related Party Transaction [Line Items]
Research and development expenses	300	$ 300	700	$ 700
Future obligations under agreement	400		400
UCL Consultants Limited | Master Services Agreement [Member] | Accounts Payable And Accrued Expenses
Related Party Transaction [Line Items]
Amount due under services agreement	$ 400		$ 400		$ 300

Related-Party Transactions - Li

Related-Party Transactions - License Agreement (Details) £ in Thousands, $ in Thousands	Mar. 23, 2020USD ($)	Mar. 15, 2018USD ($)shares	Mar. 15, 2018GBP (£)shares	Feb. 04, 2015USD ($)Program	Feb. 04, 2015GBP (£)Program	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)
Related Party Transaction [Line Items]
Research and development expenses						$ 21,612	$ 4,626	$ 53,512	$ 28,911
License Agreement [Member]
Related Party Transaction [Line Items]
Research and development expenses						60	$ 0	400	$ 200
License Agreement For Inherited Retinal Disease Programs Related To CNGB3 [Member]
Related Party Transaction [Line Items]
Ordinary shares issued in connection with a license agreement (in shares) | shares		158,832	158,832
Issuance of shares in connection with a license agreement		$ 2,000	£ 1,500
UCL Business, PLC [Member] | License Agreement [Member]
Related Party Transaction [Line Items]
Number of collaborations programs | Program				8	8
Aggregate sales milestone payments payable					£ 39,800	$ 53,600		$ 53,600
Maintenance fee				$ 70	£ 50
License arrangement upfront payment	$ 50
Development and sales milestone payments	39,300
Prosecution and maintenance costs	$ 30
UCL Business, PLC [Member] | License Agreement For Inherited Retinal Disease Programs Related To CNGB3 [Member]
Related Party Transaction [Line Items]
License arrangement upfront payment		$ 2,000	£ 1,500

Related-Party Transactions - Le

Related-Party Transactions - Leases (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Related Party Transaction [Line Items]
Operating lease rent expenses	$ 1,300	$ 800	$ 3,700	$ 2,500
Cash paid	1,234	970	3,678	2,512
ARE East River Science Park LLC [Member]
Related Party Transaction [Line Items]
Operating lease, right of use asset write-off	900		900
Operating lease liability write-off	1,000		1,000
Net gain on write-off of operating lease right of use asset and liability			100
Operating lease rent expenses	$ 0	0	$ 0	100
ARE East River Science Park LLC [Member] | Vivarium Space Operating Lease
Related Party Transaction [Line Items]
Operating lease, term of contract	12 months		12 months
Cash paid	$ 10	10	$ 50	20
Amount due	0		0		$ 0
ARE East River Science Park LLC [Member] | Vivarium Space Operating Lease | Loss from operations
Related Party Transaction [Line Items]
Operating lease rent expenses	30	10	50	20
Kadmon Corporation LLC [Member] | Loss from operations
Related Party Transaction [Line Items]
Operating lease rent expenses	$ 200	$ 200	$ 500	$ 400

Leases - Additional Information

Leases - Additional Information (Details) £ in Thousands, $ in Thousands

Aug. 04, 2020USD ($)propertycontract

Aug. 04, 2020GBP (£)propertycontract

Sep. 30, 2021USD ($)lease

Sep. 30, 2020USD ($)

Sep. 30, 2021USD ($)lease

Sep. 30, 2021GBP (£)lease

Sep. 30, 2020USD ($)

Jan. 31, 2021USD ($)

Jan. 31, 2021GBP (£)

Dec. 31, 2020USD ($)

Aug. 31, 2020USD ($)

Aug. 31, 2020GBP (£)

Lessee, Lease, Description [Line Items]

Operating lease rent expenses

$ 1,300

$ 800

$ 3,700

$ 2,500

Annual lease cost and annual maintenance fees

40

£ 30

Right-of-use asset

23,581

23,581

$ 21,486

Operating lease liability

24,525

24,525

$ 22,221

Building one

Lessee, Lease, Description [Line Items]

Capitalized building costs

$ 13,800

£ 11,900

Building two

Lessee, Lease, Description [Line Items]

Capitalized building costs

$ 8,900

£ 7,500

Vivarium Space

Lessee, Lease, Description [Line Items]

Short term lease commitments monthly amount

$ 10

$ 10

Number of short term leases | lease

1

1

Operating lease, term of contract

1 year

1 year

Janssen Pharmaceuticals Inc

Lessee, Lease, Description [Line Items]

Number of operating leases | lease

7

7

Right-of-use asset

$ 2,200

$ 2,200

Operating lease liability

$ 2,300

$ 2,300

Meira Ireland [Member] | Shannon Free Zone [Member]

Lessee, Lease, Description [Line Items]

Number of agreements | contract

2

2

Number of properties | property

2

2

Purchase price consideration

$ 21,200

£ 18,000

Minimum

Lessee, Lease, Description [Line Items]

Lease term

3 years

3 years

Minimum | Janssen Pharmaceuticals Inc

Lessee, Lease, Description [Line Items]

Operating lease, term of contract

5 years

5 years

Maximum

Lessee, Lease, Description [Line Items]

Lease term

191 years

191 years

Maximum | Janssen Pharmaceuticals Inc

Lessee, Lease, Description [Line Items]

Operating lease, term of contract

6 years

6 years

Leases - Schedule of Components

Leases - Schedule of Components of Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Amortization of right-of-use assets	$ 305	$ 82	$ 927	$ 228
Interest on lease liabilities		1	1	2
Total finance lease cost	305	83	928	230
Operating lease cost	1,293	830	3,715	2,571
Short-term lease cost	182	187	640	527
Total lease cost	$ 1,780	$ 1,100	$ 5,283	$ 3,328

Leases - Schedule of Consolidat

Leases - Schedule of Consolidated Balance Sheets for Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Operating leases
Right-of-use asset	$ 23,581	$ 21,486
Capitalized lease obligations	24,525	22,221
Finance Lease
Right-of-use asset	28,429	21,596
Capitalized lease obligations	$ 17	$ 28
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	mgtx:LeaseObligationsCurrent, mgtx:LeaseObligationsNonCurrent	mgtx:LeaseObligationsCurrent, mgtx:LeaseObligationsNonCurrent
Weighted-average remaining lease term
Operating leases	6 years 8 months 12 days	7 years
Finance leases	176 years 10 months 24 days	175 years 1 month 6 days
Weighted-Average Discount Rate
Operating leases	8.50%	8.60%
Finance leases	8.00%	8.00%

Leases - Schedule of Other Info

Leases - Schedule of Other Information Related to Leases (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from finance leases	$ 4	$ 4	$ 12	$ 17
Operating cash flows from operating leases	$ 1,234	970	3,678	2,512
Financing cash flows from finance leases		$ 1	1	$ 2
Right-of-use assets obtained in exchange for lease liabilities
Operating leases			$ 4,424

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Lease Payments Under Non-Cancellable Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Operating Leases
2021	$ 1,292
2022	5,250
2023	5,380
2024	5,221
2025	5,225
Thereafter	9,265
Total undiscounted lease payments	31,633
Less: Imputed interest	(7,108)
Operating lease liability	24,525	$ 22,221
Finance Leases
2021	4
2022	14
2023	0
2024	0
2025	0
Thereafter	0
Total undiscounted lease payments	18
Less: Imputed interest	(1)
Finance lease liability	$ 17	$ 28