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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2019	Mar. 08, 2020	Jun. 28, 2019
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Trading Symbol	MGTX
Entity Registrant Name	MeiraGTx Holdings plc
Entity Central Index Key	0001735438
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		36,817,916
Entity Public Float			$ 511,316,440.0

CONSOLIDATED BALANCE SHEETS - USD ($)	Dec. 31, 2019	Dec. 31, 2018
CURRENT ASSETS:
Cash and cash equivalents	$ 227,233,384	$ 68,080,175
Accounts receivable - related party	23,337,377
Prepaid expenses	4,464,085	1,937,785
Tax incentive receivable	11,974,437	3,416,932
Other current assets	1,970,585	1,217,173
Total Current Assets	268,979,868	74,652,065
Property and equipment, net	23,858,108	22,014,237
Security deposits	951,138	105,085
In process research and development	777,655
Restricted cash	123,376	123,376
Other assets	195,053
Right-of-use assets	29,002,448
TOTAL ASSETS	323,887,646	96,894,763
CURRENT LIABILITIES:
Accounts payable	3,759,339	3,042,861
Accrued expenses	18,083,757	11,991,697
Lease obligations, current	1,674,210	27,199
Deferred revenue - related party, current	25,678,515
Other current liabilities		437,053
Total Current Liabilities	49,195,821	15,498,810
Deferred revenue - related party	60,535,576
Lease obligations	21,504,340	7,097
Asset retirement obligations	1,654,755	128,119
Deferred rent		201,264
Deferred income tax liability	195,053
TOTAL LIABILITIES	133,085,545	15,835,290
COMMITMENTS
SHAREHOLDERS' EQUITY:
Ordinary Shares, $0.00003881 par value, 1,288,327,750 authorized 36,791,906 issued and outstanding at December 31, 2019 27,386,632 issued and outstanding at December 31, 2018	1,429	1,064
Capital in excess of par value	395,630,666	229,054,460
Accumulated other comprehensive (loss) income	(1,794,042)	293,666
Accumulated deficit	(203,035,952)	(148,289,717)
Total Shareholders' Equity	190,802,101	81,059,473
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 323,887,646	$ 96,894,763

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
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	36,791,906	27,386,632
Common stock, shares outstanding	36,791,906	27,386,632

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
License revenue - related party	$ 13,291,956
Operating expenses:
General and administrative	46,684,297	$ 44,483,938
Research and development	24,875,659	33,620,223
Total operating expenses	71,559,956	78,104,161
Loss from operations	(58,268,000)	(78,104,161)
Other non-operating income (expense):
Foreign currency gain (loss)	3,199,774	(3,824,383)
Change in fair value of warrant liability		(1,514,775)
Other income		83,075
Interest income	370,603	53,408
Interest expense	(48,612)	(33,429)
Loss before income taxes	(54,746,235)	(83,340,265)
Benefit for income taxes		474,391
Net loss	(54,746,235)	(82,865,874)
Other comprehensive (loss) income:
Foreign currency translation, net of tax of $0 and $474,391 in 2019 and 2018, respectively	(2,087,708)	2,316,143
Total comprehensive loss	(56,833,943)	(80,549,731)
Net loss	(54,746,235)	(82,865,874)
Accretion on convertible preferred C shares and warrants		(1,806,512)
Net loss attributable to ordinary shareholders	$ (54,746,235)	$ (84,672,386)
Basic and diluted adjusted net loss per ordinary share	$ (1.65)	$ (4.47)
Weighted-average number of ordinary shares outstanding	33,161,860	18,948,520

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Foreign currency translation, tax	$ 0	$ 474,391

CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED C SHARES AND SHAREHOLDERS' EQUITY (DEFICIT)	Convertible Preferred C Shares [Member] License Agreement [Member] USD ($) shares	Convertible Preferred C Shares [Member] Sales Agreement [Member] USD ($) shares	Convertible Preferred C Shares [Member] Accounts Payable [Member] USD ($) shares	Convertible Preferred C Shares [Member] USD ($) shares	Ordinary Shares [Member] IPO [Member] USD ($) shares	Ordinary Shares [Member] Vector Neurosciences Acquisition [Member] USD ($) shares	Ordinary Shares [Member] USD ($) shares	Capital in Excess of Par Value [Member] IPO [Member] USD ($)	Capital in Excess of Par Value [Member] Vector Neurosciences Acquisition [Member] USD ($)	Capital in Excess of Par Value [Member] USD ($)	Accumulated Other Comprehensive Income (Loss) [Member] USD ($)	Accumulated Deficit [Member] USD ($)	IPO [Member] USD ($)	License Agreement [Member] GBP (£) shares	License Agreement [Member] USD ($) shares	Vector Neurosciences Acquisition [Member] USD ($)	USD ($)
Beginning Balance at Dec. 31, 2017							$ 342			$ 20,080,713	$ (2,022,477)	$ (65,423,843)					$ (47,365,265)
Beginning Balance, Shares at Dec. 31, 2017 \| shares							8,826,190
Accretion of issuance costs on convertible preferred C shares										(761,012)							(761,012)
Accretion of warrants issued in connection with convertible preferred C shares				$ 1,045,500						(1,045,500)							(1,045,500)
Exercise of warrants										4,194,408							4,194,408
Conversion of convertible preferred C shares into A ordinary shares							$ 446			120,519,945							120,520,391
Conversion of convertible preferred C shares into A ordinary shares, shares \| shares							11,501,432
Sale of ordinary shares in connection with public and private placement, net of issuance costs					$ 194			$ 65,192,184					$ 65,192,378
Sale of ordinary shares in connection with public and private placement, net of issuance costs, shares \| shares					5,000,000
Issuance of ordinary shares in connection with Vector Neurosciences acquisition						$ 9			$ 2,990,241							$ 2,990,250
Issuance of ordinary shares in connection with Vector Neurosciences acquisition, shares \| shares						202,500
Share-based compensation							$ 73			17,883,481							17,883,554
Share-based compensation, shares \| shares							1,856,510
Foreign currency translation, net of income taxes											2,316,143						2,316,143
Net loss												(82,865,874)					(82,865,874)
Balance at Dec. 31, 2018							$ 1,064			229,054,460	293,666	(148,289,717)					81,059,473
Balance, Shares at Dec. 31, 2018 \| shares							27,386,632
Beginning Balance at Dec. 31, 2017				$ 51,338,631
Temporary equity, beginning Balance, Shares at Dec. 31, 2017 \| shares				5,005,935
Temporary Equity [Abstract]
Issuance of convertible preferred C shares, net of issuance costs	$ 140,000	$ 56,159,119	$ 1,356,129
Accretion of issuance costs on convertible preferred C shares				$ 761,012
Exercise of warrants				$ 9,720,000
Exercise of warrants (Shares) \| shares				927,594
Temporary Equity Shares, Conversion Of Convertible Securities \| shares				(11,501,432)
Conversion of convertible preferred C shares into A ordinary shares				$ (120,520,391)
Issuance of convertible preferred C shares, net of issuance costs (shares) \| shares	13,360	5,425,124	129,419
Issuance of ordinary shares in connection with a license agreement, shares \| shares							$ 6			1,966,334				£ 1,500,000	$ 1,966,000		1,966,340
Issuance of A ordinary shares in connection with a license agreement, shares \| shares							158,832							158,832	158,832
Exercised stock options							$ 5			557,601							557,606
Exercised stock options, shares \| shares							134,533
Exercise of warrants																	4,194,408
Conversion of convertible preferred C shares into A ordinary shares, shares \| shares							11,501,432
Sale of ordinary shares in connection with public and private placement, net of issuance costs					$ 349			$ 147,701,806					$ 147,702,155
Sale of ordinary shares in connection with public and private placement, net of issuance costs, shares \| shares					8,997,102
Share-based compensation							$ 4			15,928,966							15,928,970
Share-based compensation, shares \| shares							95,000
Issuance of ordinary shares in connection with payables							$ 1			421,499							421,500
Issuance of ordinary shares in connection with payables (shares) \| shares \| shares							19,807
Foreign currency translation, net of income taxes											(2,087,708)						(2,087,708)
Net loss												(54,746,235)					(54,746,235)
Balance at Dec. 31, 2019							$ 1,429			$ 395,630,666	$ (1,794,042)	$ (203,035,952)					$ 190,802,101
Balance, Shares at Dec. 31, 2019 \| shares							36,791,906

CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED C SHARES AND SHAREHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stock issuance costs	$ 7,497,852	$ 4,115,843
IPO [Member]
Stock issuance costs		9,807,622
Convertible Preferred C Shares [Member]
Stock issuance costs		$ 690,475

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (54,746,235)	$ (82,865,874)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Ordinary shares issued in connection with license agreements	1,966,334
Preferred C shares issued in connection with license agreements		140,000
Share-based compensation expense	15,928,970	17,883,554
Foreign currency (gain) loss	(3,199,774)	3,824,383
Depreciation	2,238,560	2,053,220
Lease obligation	1,107,805
Deferred rent		(65,189)
Amortization of interest on asset retirement obligations	20,621	(38,301)
Change in fair value of warrant liability		1,514,775
Issuance of shares for acquired research and development expense		2,990,250
Benefit for income taxes		(474,391)
(Increase) decrease in operating assets:
Accounts receivable - related party	(23,886,573)
Prepaid expenses	(2,259,984)	(35,465)
Tax incentive receivable	(8,401,283)	(3,502,692)
Other current assets	(178,805)	(181,773)
Security deposits	(796,753)	(115,573)
Increase (decrease) in operating liabilities:
Accounts payable	(8,681)	(2,119,493)
Accrued expenses	6,518,766	2,529,568
Other current liabilities		436,161
Due to Kadmon		(861,030)
Deferred revenue	85,741,929
Net cash provided by (used in) operating activities	20,044,897	(58,887,870)
Cash flows from investing activities:
Purchase of property and equipment	(8,980,425)	(11,258,479)
Purchase of Arthrogen	(389,656)
Net cash used in investing activities	(9,370,081)	(11,258,479)
Cash flows from financing activities:
Payments on lease obligations - financing leases	(24,857)	(30,852)
Exercise of warrants		9,720,000
Exercise of share options	557,606
Proceeds from the sale of ordinary shares	155,200,007	69,750,000
Issuance costs in connection with ordinary shares	(7,497,852)	(4,115,843)
Proceeds from the sale of convertible preferred C shares		56,849,594
Payment of note payable		(1,442,009)
Net cash provided by financing activities	148,234,904	130,040,415
Net increase in cash, cash equivalents and restricted cash	158,909,720	59,894,066
Effect of exchange rate changes on cash	243,489	(362,529)
Cash, cash equivalents and restricted cash at beginning of year	68,203,551	8,672,014
Cash, cash equivalents and restricted cash at end of year	227,356,760	68,203,551
Supplemental disclosure of non-cash transactions:
Fixed asset acquisition included in accounts payable and accrued expenses at end of year	1,519,454	293,051
Lease obligations for right-of-use asset	23,324,609
Reclassification of property and equipment to right-of-use asset	7,409,789
Issuance of shares in connection with payables	421,500	1,356,129
Conversion of convertible preferred C shares into ordinary shares		120,520,391
Reclassification of warrant liability upon exercise of warrants		4,194,408
Issuance costs in connection with sale of ordinary shares in accounts payable and accrued expenses at end of year		441,779
Asset retirement obligations in connection with a lease	1,501,290	(29,804)
Supplemental disclosure of cash flow information:
Cash paid for interest	$ 1,462	34,546
Convertible Preferred C Shares [Member]
Cash flows from financing activities:
Issuance costs in connection with ordinary shares		$ (690,475)

Principal Business Activity	12 Months Ended
Principal Business Activity	Dec. 31, 2019
Accounting Policies [Abstract]
Principal Business Activity	1. Principal Business Activity 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: inherited retinal 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 (“UK”), which includes fill and finish capabilities and can supply the Company’s clinical and potential commercial material. Reorganization and Initial Public Offering The Company commenced operations as MeiraGTx Limited, a private limited company incorporated under the laws of England and Wales in 2015. On June 7, 2018, in connection with its initial public offering (the “IPO”), the Company acquired all the issued and outstanding ordinary shares of MeiraGTx Limited pursuant to a series of reorganization transactions. The Company refers to these events in these notes as the “Reorganization Transactions.” In the IPO, the Company sold 5,000,000 ordinary shares (“Ordinary Shares”) at a public offering price of $15.00 per share, and received $65.2 million in net proceeds, after deducting underwriting discounts and commissions and offering expenses. Acquisition On October 17, 2019, the Company acquired 100% of the outstanding equity of Arthrogen B.V. (“Arthrogen”). Arthrogen is a biopharmaceutical company developing gene therapy for different indications, using viral mediated gene transfer. Arthrogen specializes in the development of viral gene therapy vectors, in particular adeno-associated virus (AAV-) based therapeutics. The acquisition of Arthrogen is part of the Company’s continuing efforts to expand its focus to develop additional gene therapy treatments for patients suffering from a range of serious diseases. (See Note 3 for additional information). Basis of Presentation The accompanying 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”). 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 December 31, 2019 totaled $203,035,952, 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; dependence on third parties; and dependence on key personnel. For the year ended December 31, 2019, the Company generated $20,044,897 of positive cash flows from operations. However, prior to the year ended December 31, 2019, the Company had not generated positive cash flows from operations. 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 December 31, 2019, the Company had cash, cash equivalents and restricted cash in the amount of $227,356,760, 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 received an upfront payment of $100,000,000. The Company will also receive 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, cash equivalents and restricted cash on hand at December 31, 2019 will be sufficient to cover its expenses for at least the next twelve months from the date of issuance of these 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. The Company’s capital resources and operations to date have been funded primarily with the proceeds from the Collaboration Agreement, private and public equity offerings and the IPO. 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.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Consolidation

The accompanying consolidated financial statements include the accounts of Meira Holdings and its wholly owned subsidiaries:

MeiraGTx Limited, a limited company under the laws of England and Wales (“Meira Limited”);

MeiraGTx, LLC, a Delaware corporation (“Meira LLC”);

MeiraGTx UK II Limited, (“Meira UK II”), a limited company under the laws of England and Wales;

Arthrogen, B.V., a Netherlands corporation (“Arthrogen”);

BRI-Alzan, Inc., a Delaware corporation (“BRI-Alzan”);

MeiraGTx B.V., a Netherlands corporation (“Meira BV”);

MeiraGTx Neurosciences, Inc. a Delaware corporation (“Meira Neuro”); and

MeiraGTx UK Limited (“Meira UK”), a limited company under the laws of England and Wales.

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 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 consolidated financial statements, management used significant estimates in the following areas, among others: collaboration revenue, the accounting for research and development costs, warrants, share-based compensation, leases and asset retirement obligations.

Cash and Cash Equivalents

The Company considers all highly liquid instruments with an original maturity of 90 days or less at the time of purchase to be cash equivalents. Cash and cash equivalents consist of checking and money market accounts that are readily convertible into cash.

Financial Instruments

The carrying value of accounts receivable-related party, tax incentive receivable, other current assets, and accounts payable reported in the consolidated balance sheets equal or approximate fair value due to their short maturities.

Tax Incentive Receivable

Meira UK II is eligible to participate in a UK research and development tax incentive programs under which it is eligible to receive a cash refund from Her Majesty’s Revenue & Customs (“HMRC”) for a percentage of the qualified research and development costs expended by Meira UK II under the small and medium sized enterprises (“SME”) program and the research and development expenditures credit (“RDEC”) program. The SME cash refund is available to companies with less than 500 employee and annual aggregate revenue of less than 100.0 million euro or total aggregate assets less than 86.0 million euro during the reimbursable period. The Company’s estimate of the amount of cash refund it expects to receive related to the SME and RDEC programs is included in tax incentive receivable in the accompanying consolidated balance sheets and such amounts are recorded as a reduction of research and development expense in the statements of operations. During the years ended December 31, 2019 and 2018, the Company recorded reductions to research and development expenses of $12.0 million and $3.5 million, respectively.

In addition, Meira UK II incurs Value Added Tax (“VAT”) on services provided by UK vendors, which it is entitled to reclaim. The Company’s estimate of the amount of cash refund it expects to receive related to VAT was $1.8 million and $1.1 million as of December 31, 2019 and 2018, respectively, which is included in other current assets in the accompanying consolidated balance sheet.

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 own credit risk.

The Company follows ASC Topic 820, Fair Value Measurements and Disclosures, or ASC 820, for application to financial assets and liabilities. In addition to defining fair value, the standard expands the disclosure requirements 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.

The table below represents the values of the Company's financial assets and liabilities that are required to be measured at fair value on a recurring basis:


	Fair Value Measurement Using:
			Significant		Significant Other		Significant
	December 31,		Observable Inputs		Observable Inputs		Unobservable
Description	2019		(Level 1)		(Level 2)		(Level 3)
Restricted cash	$	123,376	$	123,376	$	—	$	—
Asset retirement obligations	$	1,654,755	$	—	$	—	$	1,654,755


	Fair Value Measurement Using:
			Significant		Significant Other		Significant
	December 31,		Observable Inputs		Observable Inputs		Unobservable
Description	2018		(Level 1)		(Level 2)		(Level 3)
Restricted cash	$	123,376	$	123,376	$	—	$	—
Asset retirement obligations	$	128,119	$	—	$	—	$	128,119

The table below represents a summary of the changes in fair value of the Company’s Level 3 valuations from January 1, 2018 to December 31, 2019:


			Asset Retirement
	Warrant Liabilities		Obligations		Total
Balance as of January 1, 2018	$	2,679,633	$	178,419	$	2,858,052
Change in fair value		1,514,775		(99,090)		1,415,685
Exercise of warrants		(4,194,408)		—		(4,194,408)
Additional asset retirement obligations during the period		—		69,286		69,286
Amortization of interest		—		(38,301)		(38,301)
Effects of exchange rate		—		17,805		17,805
Balance as of December 31, 2018	$	—	$	128,119	$	128,119
Additional asset retirement obligations during the period		—		1,270,262		1,270,262
Amortization of interest		—		20,621		20,621
Change in fair value		—		255,999		255,999
Effects of exchange rate		—		(20,247)		(20,247)
Balance as of December 31, 2019	$	—	$	1,654,755	$	1,654,755

The warrants were classified as liabilities because the underlying convertible preferred C shares (“Preferred Shares”) had a redemption feature in the event of a change of control of the Company. On June 5, 2018, the warrants were exercised at which time the warrant liability was determined to be $4,194,408, which represented the difference in the market value of the Preferred Shares and the exercise price of the warrants. This resulted in an increase of the warrant liability in the amount of $1,514,775 for the period prior to exercise on June 5, 2018. The related warrant liability of $4,194,408 was reclassified as Capital in Excess of Par Value upon exercise.

The fair values of the warrants were estimated using the Black-Scholes valuation model with the following assumptions:


	June 4, 2018		December 31, 2017
Risk-free interest rate	1.77	%	1.72	%
Expected volatility	80	%	80	%
Expected dividend yield	0		0
Expected life	1 day		9 months

For the unobservable inputs for the warrants, the expected volatility was determined at each measurement date by taking an average of the volatility of other publicly-traded peer biotechnology companies. The expected life was determined at each measurement date based upon the Company’s estimate of the time until the Company had a conversion event, which occurred on June 5, 2018.

The fair value of the Preferred Shares were based upon recent issuances of the Company’s Preferred Shares on or about those dates.

The estimated fair values of the Company’s warrants were not necessarily indicative of the amounts that would have been realized in a current market exchange. The determination of the fair value of the warrants were sensitive to changes in the assumptions used and a change in those inputs could result in a significantly higher or lower fair value measurement. If the volatility were to increase or the expected life were to increase, the fair value of the warrant would increase. Conversely, if the volatility were to decrease or the expected life were to decrease, the fair value of the warrant would decrease.

The Company uses estimates to determine the amount of 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 consolidated statements of operations and comprehensive loss.

Concentrations of Credit Risk

The Company maintains its cash and cash equivalents primarily in depository and money market accounts within two large financial institutions in the United States and one large financial institution in the United Kingdom. Cash balances deposited at these major financial banking institutions exceed the insured limit. The Company has not experienced any losses on its bank deposits and believes these deposits do not expose the Company to any significant credit risk.

Property, Plant and Equipment, Net

Property, plant and equipment are stated at cost, net of accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the respective assets. Leasehold improvements are depreciated over the lesser of their useful lives or the life of the lease (see Note 5).

The estimated useful lives of the asset categories are as follows:


Asset Category		Useful Lives
Computer and office equipment		3 years
Laboratory equipment		5 years
Manufacturing equipment		7 years
Furniture and fixtures		5 years
Leasehold improvements		lesser of useful life or remaining term of lease

Expenditures for leasehold improvements are capitalized, and expenditures for maintenance and repairs are expensed to operations as incurred.

ASC Topic 360, Property, Plant and Equipment, addresses the financial accounting and reporting for impairment or disposal of long-lived assets. The Company reviews the recorded values of long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of an asset or group of assets may not be fully recoverable. The Company recorded no material impairment charges in 2019 or 2018.

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.

The Company adopted ASU 2016-02 using a modified retrospective transition approach as of the effective date as permitted by the amendments in ASU 2018-11, which provides an alternative modified retrospective transition method. As a result, the Company was not required to adjust its comparative period financial information for effects of the standard or make the new required lease disclosures for periods before the date of adoption (i.e. January 1, 2019). The Company has elected to adopt the package of transition practical expedients and, therefore, have not reassessed (1) whether existing or expired contracts contain a lease, (2) lease classification for existing or expired leases or (3) the accounting for initial direct costs that were previously capitalized. The Company did not elect the practical expedient to use hindsight for leases existing at the adoption date. Further, the Company does not expect the amendments in ASU 2018-01: Land Easement Practical Expedient to have an effect because the Company does not enter into land easement arrangements.

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 of 8%. Asset retirement obligations currently reported on the Company’s consolidated balance sheets 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.

Preferred Shares

The Preferred Shares were not redeemable, except in the event of a change of control which was outside the control of the Company and required shareholder approval. The redemption value of the Preferred Shares upon a change in control was equal to its liquidation value described below.

The Company accounted for its Preferred Shares under the requirements of ASC 480, Distinguishing Liabilities from Equity, which establishes standards for how an issuer classifies and measures certain financial instruments with characteristics of both liabilities and equity. The carrying value of the Preferred Shares was presented as temporary equity and was increased by periodic accretions so that the carrying amount would equal the redemption amount at the estimated date that the Preferred Shares would be converted into Ordinary Shares. These increases are affected through charges against additional paid-in capital, to the extent it is available, or accumulated deficit. For all Preferred Shares issuances, the difference between the amount invested by the holders of the Preferred Shares, net of issuance costs and the initial fair value of warrants issued in connection with the Preferred Shares (if applicable), and the liquidation value of the Preferred Shares was recorded as accretion over the estimated life of the Preferred Shares. The accretion was added to net loss to arrive at the net loss attributable to ordinary shareholders in the calculation of loss per ordinary share.

Share-Based Compensation Expense

Options

The Company grants share options to employees, non-employee members of the Company’s board of directors and non-employee consultants as compensation for services performed. Employee and non-employee members of the board of directors’ awards of share-based compensation are accounted for in accordance with ASC 718, Compensation - Stock Compensation, or ASC 718. ASC 718 requires all share-based payments to employees and non-employee directors, including grants of share options, to be recognized in the consolidated statement of operations and comprehensive loss based on their grant date fair values. The grant date fair value of share options is estimated using the Black-Scholes option valuation model.

Using this model, fair value is calculated based on assumptions with respect to (i) the fair value of the Company’s Ordinary Shares on the grant date; (ii) expected volatility of the Company’s Ordinary Share price, (iii) the periods of time over which the optionees are expected to hold their options prior to exercise (expected term), (iv) expected dividend yield on the Company’s Ordinary Shares, and (v) risk-free interest rates.

As there had been no public market for the Company’s Ordinary Shares until the Company’s IPO on June 7, 2018, the estimated fair value of the Ordinary Shares until that time had been determined by the Company’s board of directors as of the date of each option grant, with input from management, considering the most recently available third-party valuations of Ordinary Shares and the board of directors’ assessment of additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent valuation through the date of the grant. The assumptions underlying these valuations represented management’s best estimate, which involved inherent uncertainties and the application of management’s judgment. As a result, if the Company had used different assumptions or estimates, the fair value of its Ordinary Shares and its share-based compensation expense could have been materially different.

The fair value of Ordinary Shares after the Company’s IPO was determined based upon the closing share price on the date of grant.

Since the Company’s Ordinary Shares had not been traded on a public exchange prior to the Company’s IPO and have only been traded on a public exchange for a short period of time since the Company’s IPO, the Company believes that it does not have sufficient company-specific information available to determine the expected term based on its historical data. As a result, the expected term of share options granted to the optionees is determined using the average of the vesting period and contractual life of the option, an accepted method for the Company’s option grants under the Securities and Exchange Commission’s (“SEC”) Staff Accounting Bulletin No. 107 and No. 110, Share-Based Payment.

Similarly, the Company believes that its future volatility will differ materially during the expected term from the volatility that would be calculated from its historical share prices to date. Consequently, expected volatility is based on an analysis of guideline companies in accordance with ASC 718. The expected dividend yield is zero as the Company has never paid dividends and does not currently anticipate paying any in the foreseeable future. Risk-free interest rates are based on quoted U.S. Treasury rates for securities with maturities approximating the option’s expected term.

Restricted Shares

In connection with certain service agreements and research agreements, the Company has granted restricted Ordinary Shares as compensation. The Ordinary Shares are recognized in the consolidated statements of operations and comprehensive loss based on their grant date fair values. Compensation cost relating to share grants with service-based graded vesting schedules is recognized based on the vesting schedule.

Collaboration Arrangements

The Company evaluates its collaborative arrangements pursuant to ASC 808, Collaborative Arrangements (“ASC 808”) and ASC 606, Revenue from Contracts with Customers (“ASC 606”). The Company considers the nature and contractual terms of collaborative arrangements and assesses whether the arrangement involves a joint operating activity pursuant to which the Company is an active participant and is exposed to significant risks and rewards with respect to the arrangement. If the Company is an active participant and is exposed to significant risks and rewards with respect to the arrangement, the Company accounts for the arrangement as a collaboration under ASC 808. To date, the Company has entered into two separate collaboration agreements, both of which are with Janssen, which were determined to be within the scope of ASC 808.

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 10 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:

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

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 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 consolidated statement of operations and comprehensive loss consistent with ASC 730, Research and Development. The reimbursement of the research and development costs by Janssen is representative of the joint risk sharing nature of the arrangement. The Company considered the guidance in ASC 808 and recognizes the payments received from Janssen as a reduction to research and development expense when the related costs are incurred.

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, other costs associated with clinical and preclinical activities and regulatory operations and acquisition of in-process research and development write-offs. 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 consolidated financial statements as prepaid or accrued research and development expenses, as the case may be.

Foreign Currencies

The Company’s consolidated financial statements are presented in U.S. dollars, the reporting currency of the Company. The financial position and results of operations of Meira UK II, Arthrogen and Meira B.V. are measured using the foreign subsidiaries’ local currency as the functional currency. Meira UK II’s cash accounts holding U.S. dollars are remeasured based upon the exchange rate at the date of remeasurement with the resulting gain or loss included in the consolidated statements of operations and comprehensive loss. Expenses of such subsidiaries have been translated into U.S. dollars at average exchange rates prevailing during the period. Assets and liabilities have been translated at the rates of exchange on the consolidated balance sheet dates. The resulting translation gain and loss adjustments are recorded directly as a separate component of shareholders' equity and as other comprehensive loss on the consolidated statements of operations and comprehensive loss.

Income Taxes

Income taxes are recorded in accordance with ASC Topic 740, Income Taxes, or ASC 740, which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Realization of net deferred tax assets is dependent on future taxable income. Valuation allowances are provided, if based upon the weight of available evidence, it is more likely than not that some, or all, of the deferred tax assets will not be realized. Realization of net deferred tax assets is dependent on future taxable income (see Note 10).

The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. As of December 31, 2019 and 2018, the Company does not have any significant uncertain tax positions.

The Company is required to estimate income taxes in each of the jurisdictions in which it operates.

The Company's reserves related to taxes are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is more likely than not to be realized. As of December 31, 2019, the Company had no unrecognized tax benefits or related interest and penalties accrued.

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 Ordinary Share equivalents 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:


	December 31,	December 31,
	2019	2018
Restricted Ordinary Shares subject to forfeiture	217,726	653,174
Share options	3,645,360	3,262,365
	3,863,086	3,915,539

Other Comprehensive Income (Loss)

Other comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. The only component of other comprehensive income (loss) impacting the Company is foreign currency translation.

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 License and Collaboration Agreement are generated in the United Kingdom.

The following table summarizes non-current assets by geographical area:


	December 31,		December 31,
	2019		2018
United States	$	14,354,792	$	454,568
United Kingdom		39,476,700		21,788,130
Netherlands		1,076,286		—
	$	54,907,778	$	22,242,698

Accounting Pronouncements Recently Adopted

In February 2016, the FASB issued ASU No. 2016-02, Leases (“ASC 842” or “ASU 2016-02”). The amended guidance requires lessees to recognize lease liabilities and ROU assets on the balance sheet for all leases with initial terms longer than 12 months and provides enhanced disclosures on key information of leasing arrangements. In July 2018, further amendments were issued to clarify how to apply certain aspects of the amended lease guidance and to address certain implementation issues. The amended guidance was effective for the Company commencing on January 1, 2019. The adoption of the amended guidance materially affected the Company’s consolidated balance sheet and the primary impact was the recognition of minimum commitments at present value of the Company’s noncancelable operating leases as lease liabilities and corresponding ROU assets. In July 2018, the FASB issued ASU No. 2018-10, which provided narrow amendments to ASU 2016-02 to clarify how to apply the rate implicit in the lease, impairment of the net investment in the lease, lessee reassessment of lease classification, variable payments that depend on an index or rate and certain transition adjustments. In July 2018, the FASB also issued ASU No. 2018-11, which provides targeted improvements to ASU 2016-02 to provide entities the transition option to not apply the standard in the comparative periods presented in the year of adoption. The Company adopted the new standards effective January 1, 2019 using the modified retrospective transition method using the package of practical expedients and a discount rate of 8%, and elected to not apply the standard in the comparative periods presented in the year of adoption. Upon implementation, the Company recorded a ROU asset of $10,836,319, which included a reclassification from property and equipment of a fully paid lease entered into in 2018 in the amount of $7,409,789, and a corresponding lease obligation of $3,716,336.

In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other than Inventory, or ASU 2016-16, which requires that an entity recognize the income tax consequences of an intra-entity transfer of assets other than inventory when the transfer occurs. The guidance must be applied using the modified retrospective basis. This update was effective for the Company as of January 1, 2019. The adoption of the provisions of ASU 2016-16 did not have a material impact on the current financial statements.

On July 1, 2018, the Company early adopted ASU 2018-07, Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting (“ASU No. 2018-07”) which simplifies the accounting for share-based payments granted to nonemployees for goods and services. The ASU supersedes ASC 505-50 and expands the scope of ASC 718 to include all share-based payment arrangements related to the acquisition of goods and services from both nonemployees and employees. The adoption of ASU No. 2018-17 did not have a material effect on the consolidated financial statements.

In July 2019, the FASB issued ASU 2019-07, Codification Updates to SEC Sections - Amendments to SEC Paragraphs Pursuant to SEC Final Rule Releases No. 33-10532, Disclosure Update and Simplification, and Nos. 33-10231 and 33-10442, Investment Company Reporting Modernization and Miscellaneous Updates (SEC Update). ASU 2019-07 clarifies or improves the disclosure and presentation requirements of a variety of codification topics by aligning them with the SEC’s regulations, thereby eliminating redundancies and making the codification easier to apply. ASU 2019-07 became effective upon issuance and the adoption of ASU 2019-07, which is applied prospectively, did not have an impact on the Company’s current financial statements.

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, which adds a new Topic 326 to the Codification and removes the thresholds that companies apply to measure credit losses on financial instruments measured at amortized cost, such as loans, receivables, and held-to-maturity debt securities. Under current GAAP, companies generally recognize credit losses when it is probable that the loss has been incurred. The revised guidance will remove all recognition thresholds and will require companies to recognize an allowance for credit losses for the difference between the amortized cost basis of a financial instrument and the amount of amortized cost that the company expects to collect over the instrument’s contractual life. ASU 2016-13 also amends the credit loss measurement guidance for available-for-sale debt securities and beneficial interests in securitized financial assets. The guidance is applicable for fiscal years beginning after December 15, 2019 and interim periods within those years, however, the FASB extended the effective date for smaller reporting companies to fiscal years beginning after December 15, 2022. The Company is currently evaluating the potential impact of the adoption of this standard on its related disclosures.

In August 2018, the FASB issued ASU 2018-13, Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurements, which changes the fair value measurement disclosure requirements of ASC 820. The goal of the ASU is to improve the effectiveness of ASC 820’s disclosure requirements by providing users of the financial statements with better information about assets and liabilities measured at fair value in the financial statements and notes thereto. The guidance is applicable for fiscal years beginning after December 15, 2019 and interim periods within those years. The Company is currently evaluating the potential impact of the adoption of this standard on its related disclosures.

In August 2018, the FASB issued ASU No. 2018-15, Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. ASU 2018-15 requires that certain implementation costs incurred in a cloud computing arrangement be deferred and recognized over the term of the arrangement. The new standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019, and early adoption is permitted. The Company is currently evaluating the potential impact of the adoption of this standard on its results of operations, financial position and cash flows and related disclosures.

In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 (“ASU 2018-18”). The standard amends Accounting Standards Codification 808, Collaborative Agreements and Accounting Standards Codification 606, Revenue from Contracts with Customers, to clarify the interaction between collaborative arrangement participants that should be accounted for as revenue under ASC 606. In transactions when the collaborative arrangement participant is a customer in the context of a unit of account, revenue should be accounted for using the guidance in Topic 606. The amendments in ASU 2018-18 are effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. The Company is currently evaluating the new guidance included in ASU 2018-18, but does not expect it to have a material impact on its consolidated financial statements.

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740) – Simplifying the Accounting for Income Taxes. ASU 2019-12 simplifies the accounting for income taxes by removing exceptions within the general principles of Topic 740 regarding the calculation of deferred tax liabilities, the incremental approach for intraperiod tax allocation, and calculating income taxes in an interim period. In addition, the ASU adds clarifications to the accounting for franchise tax (or similar tax), which is partially based on income, evaluating tax basis of goodwill recognized from a business combination and reflecting the effect of any enacted changes in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date. The ASU is effective for fiscal year beginning after December 15, 2020, and will be applied either retrospectively or prospectively based upon the applicable amendments. Early adoption is permitted. The Company has elected to adopt this ASU as of January 1, 2020 on a prospective basis. The Company does not believe that this new guidance will have a material impact on its condolidate financial statements and related disclosures.

Acquisitions	12 Months Ended
Acquisitions	Dec. 31, 2019
Business Combinations [Abstract]
Acquisitions	3. Acquisitions Arthrogen B.V. On October 17, 2019, the Company acquired 100% of the outstanding equity of Arthrogen, a biopharmaceutical company developing gene therapy for different indications, using viral mediated gene transfer. Arthrogen specializes in the development of viral gene therapy vectors, in particular adeno-associated virus (AAV-) based therapeutics. The acquisition of Arthrogen is part of the Company’s continuing efforts to expand its focus to develop additional gene therapy treatments for patients suffering from a range of serious diseases. The purchase price consideration was €500,000, or approximately $558,335 and the Company utilized cash on hand. The Company incurred €94,692, or approximately $105,740 in acquisition related costs that were expensed immediately and recorded within general and administrative expenses within the Company’s consolidated statement of operations and comprehensive loss. At the time of acquisition, the net assets acquired were comprised of cash and working capital and were recorded at their respective acquisition date fair values. The excess purchase price over the net tangible assets was ascribed to in-process research and development. The acquisition was not significant to the Company’s consolidated financial statements; therefore, pro forma results of the operations related to this business acquisition for the year ended December 31, 2019 have not been presented. The immaterial results of Arthrogen’s operations since October 17, 2019 have been included in the Company’s consolidated financial statements. Vector Neurosciences On October 5, 2018, the Company entered into an agreement to acquire Vector Neurosciences Inc. (“Vector”) pursuant to an Agreement and Plan of Merger (the “Merger Agreement”) by and among the Company, Vector, VN Acquisition, Inc., a wholly-owned subsidiary of the Company (“Merger Sub 1”), VN Acquisition 2, Inc., a wholly-owned subsidiary of the Company (“Merger Sub 2”), the Vector stockholders named therein and the Vector stockholder representative, pursuant to which Merger Sub 1 was merged with and into Vector, with Vector being the surviving corporation (“Merger 1”) and, immediately following Merger 1, Vector was merged with and into Merger Sub 2, with Merger Sub 2 being the surviving corporation (together with Merger 1, the “Merger”). As a result of the Merger, Vector is a wholly-owned subsidiary of the Company. The merger consideration to Vector’s stockholders consisted of 225,000 shares of the Company’s Ordinary Shares as initial merger consideration, consisting of 202,500 shares which were issued at the closing of the Merger and an additional 22,500 shares to be issued 18 months following the closing, subject to any indemnification claims under the Merger Agreement (See Note 9). In addition, pursuant to the terms of the Merger Agreement, the Company will issue to Vector’s stockholders additional Ordinary Shares equal to a maximum value of $21,000,000 if specified regulatory milestones are met and will make royalty payments to Vector’s stockholders in an amount equal to a percentage of the value of sales of certain products developed based on the Vector assets, which royalty payments are also payable in Ordinary Shares. The number of Ordinary Shares to be issued in connection with such milestones and royalties will be based on the three-day average closing price of the Company’s Ordinary Shares immediately prior to the date of determination of the value of the payment. The Company determined this transaction represented an asset acquisition as substantially all of the value was in the intellectual property as defined by ASC 805, Business Combinations (“ASC 805”). The asset acquisition of in-process research and development was recorded at a fair value of $2,990,250 as of October 5, 2018. The acquired in-process research and development was immediately charged to research and development expense in the consolidated statement of operations and comprehensive loss as of the acquisition date since the Company determined that there was no additional alternative use of these assets. Additionally, under ASC 805, the Company determined that as of the acquisition date and as of December 31, 2019, the contingent milestone payments in the aggregate amount of $21,000,000, and royalty payments have not been resolved and therefore have not been recorded as liability.

Prepaid Expenses

12 Months Ended

Dec. 31, 2019

Other Income and Expenses [Abstract]

Prepaid Expenses

4. Prepaid Expenses

Prepaid expenses at December 31, 2019 and 2018 consist of the following:


	December 31,		December 31,
	2019		2018
Insurance	$	1,758,915	$	623,314
Clinical Trial Costs		1,609,166		373,723
Research and Development		239,161		352,658
Dues and License Fees		264,123		169,073
Rent		183,952		88,784
Other		408,768		330,233
	$	4,464,085	$	1,937,785

Property, Plant and Equipment, net

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment, net

5. Property, Plant and Equipment, net

Property, plant and equipment, net at December 31, 2019 and 2018 consist of the following:


	December 31,		December 31,
	2019		2018
Leasehold Improvements	$	17,557,316	$	11,652,055
Capitalized Leasehold Interest		—		7,150,611
Manufacturing Equipment		5,647,484		3,779,950
Laboratory Equipment		3,700,632		1,485,544
Computer and Office Equipment		1,066,984		334,525
Furniture & Fixtures		441,101		88,660
		28,413,517		24,491,345
Less: Accumulated depreciation		(4,555,409)		(2,477,108)
	$	23,858,108	$	22,014,237

On January 1, 2019, in accordance with ASU 842, the Company reclassified the capitalized leasehold interest as a ROU Asset.

In connection with six leases, the Company has determined that it has an asset retirement obligation in the aggregate amount of $3,736,404 at the end of certain of its leases. The Company discounted the asset retirement obligations using an 8% discount rate and recorded an asset retirement obligation in the aggregate amount of $1,643,794, which is included in leasehold improvements and is being depreciated over the term of the respective leases.

Capitalized leases in the amount of $95,880 are included in computer and office equipment at December 31, 2019 and 2018, with accumulated depreciation of $95,880 and $69,912 at December 31, 2019 and 2018, respectively.

Depreciation expense was $2,238,560 and $2,053,220 for the years ended December 31, 2019 and 2018 respectively.

Accrued Expenses

12 Months Ended

Dec. 31, 2019

Payables and Accruals [Abstract]

Accrued Expenses

6. Accrued Expenses

Accrued expenses at December 31, 2019 and 2018 were comprised of the following:


	December 31,		December 31,
	2019		2018
Compensation and Benefits	$	6,850,335	$	5,731,438
Clinical Trial Costs		7,788,077		4,013,094
Professional Fees		486,743		914,540
Consulting		1,247,989		821,009
Rent		283,876		122,770
Fixed Assets		1,108,362		—
Other		318,375		388,846
	$	18,083,757	$	11,991,697

Notes Payable	12 Months Ended
Notes Payable	Dec. 31, 2019
Debt Disclosure [Abstract]
Notes Payable	7. Notes Payable On October 26, 2017, in connection with an amendment and termination of a lease, the Company issued a promissory note in the amount of $1,442,009 to ARE, the landlord and also a related party (see Note 11). The note bore interest at the rate of 5% per year and was due on December 31, 2018. However, if the Company had sufficient liquidity, as defined in the note, then the note, including accrued interest, would become due and payable at that time. In accordance with the sufficient liquidity provision, the Company repaid the note, plus accrued interest, in the amount of $1,472,433 during the year ended December 31, 2018. The Company recorded interest expense in the consolidated statements of operations and comprehensive loss in connection with the note in the amount of $17,386 for the year ended December 31, 2018.

Share-Based Compensation

12 Months Ended

Dec. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-Based Compensation

8. 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 to selected officers, employees and non-employee consultants. The Company’s board of directors or a committee thereof administers the Plans. 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. Upon the adoption of the 2018 Incentive Award Plan, the Company ceased issuing awards under the 2016 Equity Incentive Plan. Under the 2018 Incentive Award Plan the Company initially reserved up to 4,150,461 shares for issuance, of which, 1,877,611 shares remain available for future issuance as of December 31, 2019. The number of shares available for issuance under the 2018 Incentive Award Plan will be increased by an annual increase on January 1 of each calendar year beginning in 2019 and ending in and including 2028, equal to the lesser of (A) 4% of the Ordinary Shares outstanding on the final day of the immediately preceding calendar year and (B) a smaller number of shares determined by the Company's board of directors. In January 2020, the number of shares available for issuance under the 2018 Incentive Award Plan increased by 1,470,421 shares. Also, in January 2020, the Company's board of directors authorized the issuance of 505,000 restricted stock units to certain executives and up to 1,117,000 options to all other employees and consultants, in each case, under the 2018 Incentive Award Plan.

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 and for the years ended December 31, 2019 and 2018 is as follows:


					Weighted-
			Weighted-		Average
			Average		Remaining
		Number of	Exercise		Contractual
		Options	Price		Life (years)
Outstanding at December 31, 2017		938,637	$	5.12
Granted		2,326,285		8.63
Exercised		—		—
Expired		—		—
Forfeited		(10,557)		(5.51)
Outstanding at December 31, 2018		3,254,365		7.64	9.24
Granted		3,645,360		17.94
Exercised		—		—
Expired		3,254,365		—
Forfeited		—		—
Outstanding at December 31, 2019		10,154,090	$	9.31	8.45
Options exercisable at December 31, 2019		1,437,281	$	7.30	7.89
Aggregate intrinsic value of options outstanding as of December 31, 2019	$	39,261,423
Aggregate intrinsic value of options exercisable as of December 31, 2019	$	18,278,490

The total fair value of options vested during the years ended December 31, 2019 and 2018 was $6,098,621 and $1,387,607, 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 (see Note 2):


	2019	2018
Risk-free interest rate	1.76 - 2.55%	2.32% - 2.84%
Expected volatility	90%	90%
Expected dividend yield	0%	0%
Expected life (in years)	5.5 - 6.1	5.5 - 9.5

The weighted average grant date fair value of options granted during the years ended December 31, 2019 and 2018 was $13.79 and $6.53, respectively.

As of December 31, 2019, the total compensation expense relating to unvested options granted that had not yet been recognized was $16,398,970, 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 Ordinary Shares

In 2015, in connection with certain service and consulting agreements, certain employees and a consultant were awarded an aggregate of 867,935 restricted Ordinary Shares of the Company. Such shares were subject to forfeiture over a three-year service period. The shares granted to the consultant and employees were valued at $7.72 and $7.76 per share, respectively, and were included in research and development expenses in the consolidated statements of operations and comprehensive loss over the requisite service period. As of December 31, 2019, all such shares were no longer subject to forfeiture as the three-year service period has been completed.

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 of such shares vested immediately, with the balance vesting quarterly over the next eight quarters beginning three months after the effectiveness of the Company’s registration statement on Form S-1 filed with the SEC on June 7, 2018 (the “Registration Statement”). The shares were valued at $15.00 per share and the related share-based compensation expense, which is recognized over the requisite service period, is included in general and administrative expenses in the consolidated statements of operations and comprehensive loss. Additionally, under the terms of the employment agreements, the Company was required to pay the income taxes incurred by the grantees in connection with the grant of those restricted shares.

Total compensation expense in connection with the issuance of those restricted Ordinary Shares, in the amount of $15,982,670 and $20,141,876, of which $6,531,744 and $10,156,868 was share-based and $9,450,926 and $9,985,008 was paid in cash, was recorded as general and administrative expense during the years ended December 31, 2019 and 2018, respectively (See Note 12).

A summary of the restricted Ordinary Shares is as follows:


	Ordinary Shares	$ Value
Non-vested at December 31, 2017	105,913	$	865,861
Issued during 2018	1,306,348		19,595,220
Vested during 2018	(759,087)		(10,663,471)
Non-vested at December 31, 2018	653,174		9,797,610
Vested during 2019	(435,448)		(6,531,720)
Non-vested at December 31, 2019	217,726	$	3,265,890

Ordinary Shares

On March 1, 2018, a funding milestone was met under the employment agreements for certain members of senior management. Accordingly, the employees were issued an aggregate of 550,162 fully vested Ordinary Shares, which represented 3% of the fully-diluted outstanding shares of the Company as of such date. The shares were recorded as share-based compensation in the amount of $3,096,104. Additionally, under the terms of the employment agreements, the Company was required to pay the income taxes incurred by the grantees in connection with the grant of those shares. Total compensation expense in connection with the issuance of those Ordinary Shares, in the amount of $6,456,215, of which $3,096,104 was share-based, was recorded as general and administrative expense during the year ended December 31, 2018.

On October 31, 2019, the Company issued 95,000 shares to a consultant in the amount of $1,372,750.

During the years ended December 31, 2019 and 2018 the Company recognized total share-based compensation expense in the accompanying consolidated statements of operations and comprehensive loss as follows:


	2019		2018
Research and development	$	5,059,046	$	3,372,054
General and administrative		10,869,924		14,511,500
Total share based compensation	$	15,928,970	$	17,883,554

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 years ended December 31, 2019 and 2018.

Ordinary Shares, Preferred Shares and Shareholders' Deficit	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Ordinary Shares, Preferred Shares and Shareholders' Deficit	9. Ordinary Shares, Preferred Shares and Shareholders’ Deficit Ordinary Share Issuances 2019 Private Placement On February 27, 2019, the Company issued 5,797,102 ordinary shares in a private placement for gross proceeds of $80 million, excluding offering costs of approximately $2.4 million. Johnson & Johnson Innovation – JJDC, Inc. (“JJDC”), the investment arm of Johnson and Johnson and owner of Janssen, purchased 2,898,550 of the ordinary shares issued on the same terms and conditions as the other investors in the offering. In connection with the offering, the Company also entered into a registration rights agreement whereby, promptly following the date on which the Company becomes eligible to use a registration statement on Form S-3, but in no event later than July 31, 2019, the Company shall prepare and file a registration statement covering the resale of all of the Registrable Securities, as defined in the agreement. The Company filed the Form S-3 on July 2, 2019 and the Form S-3 was declared effective on July 16, 2019. Public Offering On August 7, 2019, the Company issued 3,200,000 ordinary shares in a public offering for gross proceeds of $75 million, excluding offering costs of approximately $5.1 million. License Agreement As discussed in Note 11, on March 21, 2019, the Company issued 158,832 ordinary shares in connection with a license agreement. In accordance with the license agreement, the cost basis of the shares was based on the closing share price on January 31, 2019. Other Issuances On July 7, 2019, the Company issued 19,807 shares to a vendor in the amount of $421,500. On October 31, 2019, the Company issued 95,000 shares to a consultant in the amount of $1,372,750. 2018 As discussed in Note 13, on March 1, 2018, a funding milestone was met under the employment agreements for certain members of senior management. Accordingly, the employees were issued an aggregate of 550,162 fully vested Ordinary Shares. In connection with the Company’s initial public offering, on June 7, 2018, the Company issued 5,000,000 Ordinary Shares at an offering price of $15.00 per share for gross proceeds of $75,000,000, excluding offering costs of $9,807,622. Also, as discussed in Note 13, on June 7, 2018, upon the effectiveness of the Company’s Registration Statement, 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 of such shares vested immediately, with the balance vesting quarterly over the next eight quarters. On October 5, 2018, in connection with an acquisition, the Company issued 202,500 Ordinary Shares with an additional 22,500 shares to be issued 18 months following the closing, subject to any indemnification claims under the merger agreement. Preferred Shares Issuances 2018 During the year ended December 31, 2018, the Company issued 5,425,124 Preferred Shares at an offering price of approximately $10.48 per share for gross proceeds of $56,849,611, excluding offering costs of $690,475. Also, during the year ended December 31, 2018, the Company issued 129,419 Preferred Shares in lieu of payment of accounts payable in the aggregate amount $1,356,129 to certain vendors. On March 15, 2018, the Company issued 13,360 Preferred Shares in connection with a license agreement. On June 5, 2018, the Company issued 927,594 Preferred Shares in connection with the exercise of 3,600,000 warrants. On June 7, 2018, upon effectiveness of the Company’s Registration Statement on Form S-1, all of the 11,501,432 outstanding Preferred Shares were automatically converted into 11,501,432 Ordinary Shares. In connection with the conversion of the Preferred Shares, $664,718 of unaccredited financing costs were fully accreted.

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

10. Income Taxes

For the years ended December 31, 2019 and 2018, the Company recognized a tax benefit of $0 and $(474,391), respectively.

As of December 31, 2019, the Company had federal and state net operating loss (“NOL”) carryforwards which are available to reduce future taxable income of:


	Federal		State
United States	$	27,552,418		27,493,036
United Kingdom	$	107,287,003		—
Netherlands	$	22,808,090		—

The U.S. federal and state NOL carry forwards incurred prior to January 1, 2018 in the amount of approximately $6.8 million and $6.7 million, respectively, will begin to expire in 2036. The U.S. NOL incurred after December 31, 2017 and the UK NOL will be indefinitely carried forward. The Netherlands NOL’s expire after nine years from the date incurred. Also, as of December 31, 2019, the Company had orphan drug and research and development credits in the U.S. in the amount of $2,391,137 which will begin to expire 2036. The NOL carry forwards are subject to review and possible adjustment by the U.S., UK, Netherlands and state tax authorities. NOL carry forwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders, as defined under Sections 382 Internal Revenue Code, as well as CTA 2010 Part 14 under the UK tax rules. This could limit the amount of NOLs that the Company can utilize annually to offset future taxable income or tax liabilities. As of December 31, 2018, the Company had performed such an analysis and determined that there were no limitations in the UK However, for U.S. purposes, the Company determined that a change of ownership occurred in November 2016. The Company is still in the process of determining the annual limitation on losses that occurred prior to November 2016. Subsequent ownership changes and proposed future changes to the UK (or U.S.) tax rules in respect of the utilization of losses carried forward may further affect the limitation in future years, if any. Additionally, the Company has begun a study on the completeness of the U.S. orphan drug and research and development credit.

The Company's pre tax earnings are as follows:


	December 31, 2019		December 31, 2018
United Kingdom	$	(37,993,537)	$	(73,359,978)
United States		(16,303,213)		(9,980,287)
Netherlands		(449,485)		—
	$	(54,746,235)	$	(83,340,265)

The Company is subject to the corporate tax rate in the UK as a limited UK corporation.

The following table summarizes a reconciliation of income tax benefit compared with the amounts at the UK statutory income tax rate:


	December 31, 2019			December 31, 2018
Statutory rate	(10,401,785)	19.00	%	(15,834,650)	19.00	%
Permanent differences - other	(411,651)	0.75	%	1,438,934	(1.73)	%
RTP and other adjustment	3,068,999	(5.61)	%	387,509	(0.46)	%
State and local rate, net of federal tax	(2,041,097)	3.73	%	(1,159,522)	1.39	%
U.K. Tax credit	1,278,072	(2.33)	%	1,707,489	(2.05)	%
U.S. Tax credit	(1,257,481)	2.30	%	(436,250)	0.52	%
Foreign tax rate differential	(347,301)	0.63	%	(171,693)	0.21	%
UK Rate change (17% at exxpected DTA turn)	362,092	(0.66)	%	1,104,863	(1.33)	%
US state rate change	—	0.00	%	(6,496)	0.01	%
Change in valuation allowance	9,750,153	(17.81)	%	12,495,425	(14.99)	%
Actual income tax benefit effective tax rate	—	0.00	%	(474,391)	0.57	%

The Expense/(Benefit) for income taxes from continuing operations consists of the following:


	December 31, 2019	December 31, 2018
Current Tax Expense/(Benefit)
United Kingdom	—	—
United States	—	—
Netherlands	—	—
Total Current	—	—
Deferred Tax Expense/(Benefit)
United Kingdom	(3,036,499)	(8,888,096)
United States	(6,631,936)	(3,606,275)
Netherlands	(81,718)	—
Total Deferred	(9,750,154)	(12,494,371)
Change in Valuation Allowance	9,750,154	12,019,980
Total Income Tax Expense/(Benefit)	—	(474,391)

Income tax (benefit) expense for each year is allocated to continuing operations, discontinued operations, extraordinary items, other comprehensive income, the cumulative effects of accounting changes, and other charges or credits recorded directly to shareholders’ equity. ASC 740-20-45 Income Taxes, Intraperiod Tax Allocation, Other Presentation Matters includes an exception to the general principle of intraperiod tax allocations. The codification source states that the tax effect of pretax income or loss from continuing operations generally should be determined by a computation that considers only the tax effects of items that are included in continuing operations. The exception to that incremental approach is that all items (i.e. other comprehensive income, discontinued operations, etc.) be considered in determining the amount of tax benefit that results from a loss from continuing operations and that benefit should be allocated to continuing operations. That is, when a company has a current period loss from continuing operations, management must consider income recorded in other categories in determining the tax benefit that is allocated to continuing operations. This includes situations in which a company has recorded a full valuation allowance at the beginning and end of the period, and the overall tax provision for the year is zero. The intraperiod tax allocation is performed once the overall tax provision has been computed and allocates that provision to various income statement (continuing operations, discontinued operations), other comprehensive income and balance sheet captions. While the intraperiod tax allocation does not change the overall tax provision, it results in a gross-up of the individual components. The level of application has been applied on the group level.

As the Company experienced a net loss from operations for the year ended December 31, 2018 and other comprehensive income from foreign currency translation adjustments, the Company allocated income tax expense against the components of other comprehensive income in 2018 using a 17% effective tax rate. Income tax benefit for the year ended December 31, 2018 includes a benefit $(474,391) due to the required intraperiod tax allocation. Conversely, other comprehensive income for the year ended December 31, 2018 includes income tax expense $474,391.

Deferred Tax Assets/(Liabilities)


	December 31, 2019
	Total		UK		US		Netherlands
Deferred Tax Assets:
Net operating loss carryforwards	$	31,929,792	$	18,238,791	$	9,015,343	$	4,675,658
Lease Liability		6,012,466		1,704,357		4,308,109		—
Other		2,581,842		485,724		2,108,121		(12,003)
R&D Credit		2,635,188		244,051		2,391,137		—
Deferred tax assets		43,159,288		20,672,923		17,822,710		4,663,655

Deferred Tax Liabilities:
Indefinite-lived intangibles & Fixed Asset PPA		(173,431)		—		—		(173,431)
Right of use assets		(5,635,987)		(1,686,019)		(3,949,968)		—
Less: valuation allowance		(37,523,301)		(18,986,904)		(13,872,742)		(4,663,655)
Net deferred tax liability	$	(173,431)	$	—	$	—	$	(173,431)


	December 31, 2018
	Total		UK		US		Netherlands
Deferred Tax Assets:
Net operating loss carryforwards	$	20,646,185	$	15,997,008	$	4,645,856	$	3,321
Other		1,414,690		(46,604)		1,461,294		—
R&D Credit		1,133,656		—		1,133,656		—
Deferred tax assets		23,194,531		15,950,404		7,240,806		3,321
Less: valuation allowance		(23,194,531)		(15,950,404)		(7,240,806)		(3,321)
Net deferred tax asset	$	—	$	—	$	—	$	—

ASC 740 requires a valuation allowance to reduce the deferred tax assets reported if, based on the weight of available evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. After consideration of all the evidence, both positive and negative, the Company has recorded a full valuation allowance, after consideration of the reversal of the deferred tax liabilities for the ROU assets and fixed assets, against its deferred tax assets at December 31, 2019 and 2018 because the Company's management has determined that is it more likely than not that these assets will not be fully realized.

Changes to the UK corporation tax rates have been announced which will impact future accounting periods. In his budget of July 8, 2015, the Chancellor of the Exchequer announced a reduction in the UK corporation tax rate to 19% for the financial year beginning April 1, 2017 and a further reduction to 18% for the financial year beginning April 1, 2020. These changes received Royal Assent on November 18, 2015. The UK Finance Act 2016 provides for a further reduction in the corporation tax rate to 17% for the Financial Year beginning April 1, 2020. This change was enacted on September 15, 2016. As the Company does not expect to be able to utilize its NOL’s in the UK prior to its financial year beginning on January 1, 2021, if at all, the deferred tax has been calculated using a tax rate of 17%.

The Company will recognize interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2019 and 2018, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company's statements of operations and comprehensive loss.

The Company files income tax returns in the United States, UK and Netherlands and various state jurisdictions. In the United States, tax years 2016, 2017 and 2018 remain subject to examination. In the United Kingdom, tax year 2018 remains subject to examination. In the Netherlands, tax years 2014, 2015, 2016, 2017 and 2018 remain subject to examination.

MeiraGTx Holdings plc is a UK tax resident with no earnings in its foreign subsidiaries and the Company does not expect any temporary basis difference in its investment in these subsidiaries to reverse in the foreseeable future. Therefore, the Company has not recorded deferred taxes on the outside basis difference in its foreign subsidiaries. It is not probable to compute the amounts, if any.

Related Party Transactions

12 Months Ended

Dec. 31, 2019

Related Party Transactions

11. 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 IRD. 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 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 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.

During the year ended December 31, 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 year ended December 31, 2019, the Company recognized $13,291,956, of the deferred revenue – related party as license revenue. The Company also recognized $27,296,062, during the year ended December 31, 2019 related to the reimbursement of research and development expenses, which was recorded as an offset to research and development expenses. As of December 31, 2019, the Company expects to recognize the remaining $86,214,091 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 5.5 years.

A summary of the deferred revenue recognition is as follows:


Non-refundable upfront fee from Janssen	$	100,000,000
Deferred revenue recognized as license revenue during the year ended December 31, 2019		(13,291,956)
Effects of exchange rate		493,053
Deferred revenue at December 31, 2019	$	86,214,091

Riboswitch Research Collaboration Agreement

On October 16, 2018, the Company entered into a riboswitch research collaboration agreement with Janssen, to develop regulatable gene therapy treatment using the Company’s proprietary riboswitch technology. As part of the agreement, the Company will use its proprietary riboswitch technology to engineer regulatable gene therapy constructs encoding proprietary gene sequences from Janssen.

Upon execution of the agreement, Janssen paid the stage 1 fee in the amount of $658,667, and such payment was recorded as deferred revenue – related party. The stage 1 fee was being amortized over the estimated research term of eight months. During the year ended December 31, 2019, the Company amortized the remaining $444,399 of the deferred revenue, which was recorded as an offset to research and development expenses. Additionally, the stage two fee, in the amount of $328,524 was recorded and fully amortized during the year ended December 31, 2019.

Research Agreement

Effective October 23, 2016, the Company entered into a four-year master services agreement with UCL Consultants Limited, an entity affiliated with University College of London (“UCL”), which is a shareholder of the Company. Pursuant to the agreement, UCL Consultants Limited provides pre-clinical research and development under the direction of the Company. Either party may terminate the agreement by giving 30 days written notice.

Total research and development expenses under this agreement for the years ended December 31, 2019 and 2018 was approximately $306,000 and $636,000, respectively.

Future obligations under the agreement equal £165,878, or approximately $218,000 through, October 2020.

The amount due to UCL under the master services agreement at December 31, 2019 and 2018 is $166,404 and $389,101, respectively, and is included in accounts payable and accrued expenses on the Company’s 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 $52.4 million using the exchange rate at December 31, 2019, 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 £50,000, or approximately $66,000, 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 10th 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; (b) ACHM caused by mutations in CNGA3; (c) X-linked retinitis pigmentosa (“XLRP”); and (d) RPE65-mediated IRD.

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 £1,500,000, or approximately $1,976,000, and issued 158,832 of the Company’s Ordinary Shares, which were valued at £1,500,000, or approximately $1,966,000.

The Company incurred research and development expenses under the agreements in the amount of $4,271,275, inclusive of the amendment payments of approximately $3,942,000, and $325,431 during the years ended December 31, 2019 and 2018, 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”), an entity that is under common control by an entity that is a minority shareholder of the Company and whose executive chairman and founder is a director of the Company. The ARE Lease provides for monthly base rent and property management fees, including rent escalations and rent holidays, plus operating expenses during the lease term, which expires on December 31, 2021. The Company records monthly rent expense on a straight-line basis from July 1, 2016 through December 31, 2021. As of December 31, 2018, the balance of deferred rent, representing the difference between cash rent paid and straight-line rent expense, was $201,264. As of December 31, 2019, and in accordance with ASC 842, the difference between cash rent paid and straight-line rent expense of $153,146 is reflected in the ROU asset.

Total rent expense under this operating lease was $487,555 for each of the years ended December 31, 2019 and 2018.

As of December 31, 2019, the aggregate future minimum rental payments under this lease are $1,128,269.

In connection with the signing of this lease, the Company entered into a standby letter of credit agreement for $122,866, which serves as a security deposit for the premises. The standby letter of credit initially expired on July 7, 2017, and is automatically renewed annually through July 7, 2021. This standby letter of credit is secured with restricted cash in a money market account in the amount of $123,676 at December 31, 2019 and 2018.

The restricted cash is included in long-term assets as of December 31, 2019 and 2018 and is measured using level 1 inputs.

The aggregate future minimum rental payments under this lease as of December 31, 2019 for years ending December 31 are as follows:


2020	$	554,432
2021		573,837
Total future rent payments	$	1,128,269

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.

Transition Services Agreement

Effective April 24, 2015, the Company entered into a transition services agreement (the “TSA”) with Kadmon Holdings, Inc. (“Kadmon”), which owned 5.8% and 12.9% of the Company at December 31, 2019 and 2018, respectively, whereby Kadmon would provide office and laboratory facilities as well as certain other personnel support activities to the Company. Under the agreement, the Company was charged for (i) rent based upon the square footage of the office and laboratory facilities used by the Company (ii) other personnel support activities based upon the hours of the personnel providing the support activities, and (iii) and other direct costs incurred by Kadmon on behalf of the Company, plus a 7% administrative fee. The TSA terminated on April 24, 2018 and the Company is currently leasing office space on a month to month basis from Kadmon.

During the years ended December 31, 2019 and 2018, the Company incurred the following charges, which are included in loss from operations:


	2019		2018
Rent	$	576,404	$	557,698
Personnel		—		6,493
Other		—		6,334
Total charges incurred	$	576,404	$	570,525

During the year ended December 31, 2019 and 2018, the Company made cash payments to Kadmon totaling $576,404 and $1,431,555, respectively.

There were no cash payments due to Kadmon at December 31, 2019 and 2018.

Lease Obligations

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Lease Obligations

12. Lease Obligations

The Company has commitments under operating leases for laboratory and office space. 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 108 years. Certain lease agreements contain provisions for future rent increases. Payments due under the lease contracts include fixed payments.

New York Sublease

Effective May 31, 2019, the Company entered into a non-cancelable operating sublease with an unrelated third party for laboratory and office space in New York. The lease, which expires on October 31, 2026, provides for monthly base rent and property management fees, including rent escalations and rent holidays, plus operating expenses during the lease term. The Company records monthly rent expense on a straight-line basis from June 20, 2019, the date the Company was allowed to access the leased premises, through October 31, 2026, when the sublease is set to terminate. In conjunction with this operating sublease, the Company recognized an initial operating lease ROU asset and corresponding operating lease liability of $11.8 million which is included in ROU assets and lease obligations on the consolidated balance sheets.

Total cash payments made under this operating lease were $180,000 for the year ended December 31, 2019.

Total rent expense recognized under this operating lease was $1,110,847, for the year ended December 31, 2019.

Tudor Street Lease

Effective June 11, 2019, the Company entered into a non-cancelable operating lease with an unrelated third party for warehouse space in London. The lease, which expires on June 10, 2029, provides for quarterly base rent and operating expenses during the lease term. The Company has the right to terminate this lease on June 10, 2024 by giving the landlord notice at least six months prior to such date. If the Company does not terminate the lease on June 10, 2024, then the annual rent is subject to a one-time adjustment based on the then current market conditions on June 11, 2024. As the Company does not expect to exercise its right to terminate the lease prior to the expiration date, the Company records monthly rent expense on a straight-line basis from June 11, 2019, the date the Company took possession of the leased premises, through June 10, 2029, when the lease is set to terminate. In conjunction with this operating lease, the Company recognized an initial operating lease ROU asset and corresponding operating lease liability of £1.2 million, or approximately $1.5 million, which is included in ROU assets and lease obligations on the consolidated balance sheets.

Total cash payments made under this operating lease were £127,800, or approximately $168,000, for the year ended December 31, 2019.

Total rent expense recognized under this operating lease was £82,149, or approximately $108,000, for the year ended December 31, 2019.

Provost Street Lease

On May 29, 2019, the Company entered into an Agreement for Lease with an unrelated third party which provided a license to lease an entire building consisting of five floors of office and laboratory space in London. The leased premises were being renovated by the landlord with such renovations being completed in September 2019. Upon completion of the landlord renovations, the Company entered into a non-cancellable operating lease, which expires on September 8, 2029. The lease provides for quarterly base rent, including a rent holiday at the commencement of the lease, plus operating expenses during the lease term. The Company has the right to terminate this lease on September 8, 2024 by giving the landlord notice at least six months prior to such date. If the Company does not terminate the lease on by September 8, 2024, then the annual rent is subject to a one-time adjustment based on the then current market conditions on September 9, 2024. As the Company does not expect to exercise its right to terminate the lease prior to the expiration date, the Company records monthly rent expense on a straight-line basis from September 11, 2019, the date the Company took possession of the leased premises, through September 8, 2029, when the lease is set to terminate. In conjunction with this operating lease, the Company recognized an operating lease ROU asset and corresponding operating lease liability of £4.9 million, or approximately $6.5 million, which is included in ROU assets and lease obligations on the consolidated balance sheets.

Total cash payments made under this operating lease were £0, for the year ended December 31, 2019.

Total rent expense recognized under this operating lease was £238,222, or approximately $314,000, for the year ended December 31, 2019.

Ebenezer Street Leases

On July 27, 2018, two leases with an unrelated third party for office and laboratory facilities in London expired and the Company entered into two new non-cancellable operating leases with the same unrelated third party for the same office and laboratory facilities. The leases, which expire on May 24, 2027, provide for quarterly base rent, plus operating expenses, during the lease term. The Company has the right to terminate this lease on May 31, 2022 by giving the landlord notice at least six months prior to such date. If the Company does not terminate the lease on May 31, 2022, then the annual rent is subject to a one-time adjustment based on the then current market conditions. As the Company does not expect to exercise its right to terminate the lease prior to the expiration date, the Company records monthly rent expense on a straight-line basis from July 27, 2018 through May 24, 2027, when the leases are set to terminate. In conjunction with these operating leases, the Company recognized an initial operating lease ROU asset and corresponding operating lease liability of £1.7 million, or approximately $2.3 million, which is included in ROU assets and lease obligations on the consolidated balance sheets.

Total cash payments made under these operating leases were £274,969 and £137,485, or approximately $362,000 and $169,000, for the years ended December 31, 2019 and 2018, respectively.

Total rent expense recognized under these operating leases was £274,969 and £137,485, or approximately $362,000 and $169,000, for the years ended December 31, 2019 and 2018, respectively.

As of December 31, 2019, the Company has short term lease commitments amounting to approximately $52,000 on a monthly basis for three leases for office space that are month-to-month leases.

The components of lease cost for the year ended December 31, 2019 are as follows:


Finance lease cost
Amortization of right-of-use assets	$	300,229
Interest on lease liabilities		2,409
Total Finance Lease Cost		302,638
Operating lease cost		2,384,048
Short-term lease cost		1,282,709
Total lease cost	$	3,969,395

Amounts reported in the consolidated balance sheets for leases where the Company is the lessee as of December 31, 2019 were as follows:


Operating leases
Right of Use Asset	$	21,857,600
Capitalized Lease Obligations	$	23,127,813
Finance leases
Right-of-Use Asset	$	7,144,848
Capitalized Lease Obligations	$	50,737
Weighted-Average Remaining Lease Term
Operating leases		7.9	years
Finance leases		107.0	years
Weighted-Average Discount Rate
Operating Leases		8.5	%
Finance Leases		7.3	%

Other information related to leases as of the year ended December 31, 2019 are as follows:


Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from finance leases	$	28,187
Operating cash flows from operating leases	$	1,246,169
Financing cash flows from finance leases	$	2,355

Right-of-use assets obtained in exchange for lease liabilities
Operating leases	$	23,279,980
Finance leases	$	44,629

Future minimum lease payments under non-cancellable leases as of December 31, 2019 are as follows:


	Operating Leases		Finance Leases
2020	$	3,555,287	$	26,451
2021		3,888,355		16,880
2022		3,955,076		12,660
2023		4,023,799		—
2024		3,826,294		—
Thereafter		10,708,509		—
Total undiscounted lease payments	$	29,957,320	$	55,991
Less: Imputed interest		(6,829,507)		(5,254)
Total lease liabilities	$	23,127,813	$	50,737

Commitments	12 Months Ended
Commitments	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments	13. Commitments Service Agreements On April 27, 2015, the Company entered into service agreements with two senior officers of the Company. Under the terms of the agreements, the employees will receive aggregate compensation of £300,000, which has been increased to a maximum aggregate amount of £430,000 per year, or approximately $566,000. The agreements also provide for contributions to a defined contribution pension plan to be set up by the Company and a discretionary bonus. The agreements may be terminated at any time by either party by giving twelve-months’ notice, or the Company may terminate the officer’s employment effective immediately upon notice, and within 28 days after making payment in lieu of notice consisting of a sum equivalent to the officer’s annual salary for the relevant period. For the years ended December 31, 2019 and 2018, the Company recorded £944,500 and £1,001,000 or approximately $1,234,000 and $1,334,000, respectively, in research and development costs under these agreements. Future obligations to be paid under these agreements equal £157,000, or approximately $207,000 at December 31, 2019. In connection with the service agreements, on April 24, 2015, the employees were awarded, under a share award agreement (the “Share Award Agreement”), an aggregate of 696,933 restricted Ordinary Shares and 193 B ordinary shares, which B ordinary shares have been converted into Ordinary Shares of the Company. Under the Share Award Agreement, such shares are subject to forfeiture ratably over a period of three years if the employee’s do not remain an employee or consultant to the Company. The shares were valued at $7.76 per share and, in accordance with ASC 718, were charged to operations as share-based compensation ratably over the forfeiture period. As of December 31, 2019, all such shares were no longer subject to forfeiture as the three-year service period had been completed. Employment Agreements In February 2016, the Company entered into three-year employment agreements with certain senior officers of the Company. Under the terms of the agreements, which automatically renew for successive one-year terms, the employees will receive annual compensation in the aggregate amount of $710,000, which has been increased to a maximum aggregate amount of $1,075,000. The employment agreements also provide for an annual guaranteed cash bonus targeted at 100% of annual compensation. The agreements also provide for discretionary annual performance bonuses targeted to be not less than 50-60% of the employee’s base salary and grants of restricted shares. In January 2018, the Company’s compensation committee approved a discretionary bonus in the aggregate amount of $1,196,000. This discretionary bonus and the guaranteed bonus for 2017, in the aggregate amount of $850,000, were subject to compensation committee approval and meeting certain future funding conditions. On February 28, 2018, the funding conditions were met. Bonuses granted to the senior officers, which included their guaranteed and discretionary bonuses, for the years ended December 31, 2019 and 2018, in the aggregate amount of $5,403,000 and $3,415,000 were paid in January of the subsequent years. Additionally, the agreements provided for equity incentives of up to an aggregate maximum of 8.0% of the Company’s fully diluted outstanding shares upon the attainment of certain milestones. On March 1, 2018, a funding milestone was met. Accordingly, the employees were issued an aggregate of 3% of the fully-diluted outstanding shares of the Company as of such date. On June 7, 2018, an additional milestone was met. Accordingly, the employees were issued an aggregate of 5% of the fully-diluted outstanding shares of the Company as of such date (see Note 9). The employees are also entitled to participate in all incentive and deferred compensation and employee benefit programs available to employees and executive officers of the Company. Future obligations to be paid under these agreements equal $2,418,750, as of December 31, 2019. Consulting and other Agreements Effective September 28, 2015, the Company entered into a three-year consulting agreement with a consultant to provide ongoing strategic advice and to serve on the Company’s board of directors. In connection with the agreement, the Company issued 170,809 restricted Ordinary Shares. Under the consulting agreement, such shares were subject to forfeiture ratably over a period of three years if the consultant does not remain a consultant to the Company. The shares were valued at $7.72 per share and were charged to general and administrative expenses upon the expiration of each forfeiture period. For the years ended December 31, 2019 and 2018, the Company recorded $0 and $263,970, respectively, in general and administrative expense under this agreement. As of December 31, 2019, all such shares were no longer subject to forfeiture as the three-year service period had been completed. Research Agreements On April 24, 2015, the Company entered into a cooperative research and development agreement (“CRADA”) with the U.S. Department of Health & Human Services, as represented by the National Institute of Dental and Craniofacial Research (“NIDCR”) and Institute or Center of the National Institutes of Health (“NIH”). The CRADA provided for quarterly payments of $21,250 for three years through April 30, 2017 and a cost per patient for each patient enrolled in the Company’s xerostomia clinical trial. The CRADA was amended on March 25, 2016 to extend the term through March 25, 2021 and to extend the annual payments throughout the revised term. Research and development expenses under the CRADA for the years ended December 31, 2019 and 2018 were $117,592 and $111,938, respectively. Future obligations to be paid under the CRADA, as amended, through March 25, 2021 equal $106,250. On March 22, 2016, the Company entered into another CRADA with the NIDCR and NIH for the treatment of Sjögren’s syndrome associated salivary hypofunction. The CRADA provided for quarterly payments of $104,500 for the first three years of the agreement plus a cost per patient for each patient enrolled in a clinical trial. The costs associated with years four and five of the Sjögren’s syndrome CRADA will be determined at a later date. Total research and development expenses under this agreement for the years ended December 31, 2019 and 2018 were $92,657 and $418,000, respectively. There are no future obligations to be paid under the agreement. Effective December 5, 2016, the Company entered into a three-year research collaboration agreement with Cornell University. Pursuant to the agreement, Cornell University provides research and development under the direction of the Company. In connection with the agreement, in July 2017, the Company issued 6,441 Ordinary Shares to Cornell University, which were recorded as research and development expenses in the amount of $17,000. The Company amended this agreement, effective June 12, 2017, to add a second three-year research collaboration project through September 2019. The Company further amended this agreement, effective October 18, 2018 to include additional costs related to the research. Total research and development expenses under this agreement, as amended, for the years ended December 31, 2019 and 2018 were $1,756,487 and $1,625,152, respectively. Future obligations to be paid under the agreements are $206,984. On February 14, 2017, the Company entered into a one-year research collaboration agreement with Cornell University in the amount of $679,473. On August 24, 2017, the agreement was amended to add an additional study in the amount of $182,520. Total research and development expenses under this agreement for the years ended December 31, 2019 and 2018 were $20,613 and $143,073, respectively. License Agreements On September 7, 2018, the Company entered into an exclusive licensing agreement with the National Institutes of Health for worldwide rights to expanded indications for use of AAV-AQP1 for treatment of xerostomia (dry mouth) and xerophthalmia (dry eye) associated with Sjögren's syndrome. This agreement expands the Company’s original exclusive licensing agreement with the NIH for exclusive worldwide rights to AAV-AQP1 that was executed as of November 9, 2017. AAV-AQP1 is currently in Phase 1/2 development for treatment of grade 2 or 3 radiation-induced xerostomia. Total research and development expenses under the agreement for the years ended December 31, 2019 and 2018 were $60,000 and $50,000, respectively. Effective January 1, 2016, the Company acquired all of the outstanding shares of BRI-Alzan from the shareholders of BRI-Alzan. In connection with the Agreement, the Company will pay certain development milestone payments if achieved, in the aggregate amount of $4.5 million, and annual royalty payments on annual net sales following the first commercial sale of any product containing the technology acquired. Total research and development expenses under the agreement for the years ended December 31, 2019 and 2018 were $15,000 and $15,000, respectively.

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2019
Postemployment Benefits [Abstract]
Employee Benefit Plans	14. Employee Benefit Plans United States On January 1, 2017, Meira LLC adopted a defined contribution retirement plan that complies with Section 401(k) of the Internal Revenue Code. All Meira LLC employees over the age of 21 are eligible to participate in the plan after three consecutive months of service. Employees are able to defer a portion of their pay into the plan on the first day of the month or after the day all age and service requirements have been met. The plan provides for a Company matching contribution. All eligible employees receive an employer matching contribution equal to the lesser of the amount the employee contributes to the plan or 6% of their salary up to the annual IRS limit. United Kingdom On August 1, 2016, Meira UK II adopted a defined contribution group personal pension plan that complies with HMRC for tax relief. All Meira UK II employees are eligible to participate in the plan upon joining the company and providing the required services. All eligible employees, if they elect to join the pension scheme, receive an employer pension contribution equal to 7.5% to 10.0% of their pensionable earnings. Currently, employees are not required to contribute, but may make optional contributions up to the annual allowance HMRC limits. Under the HMRC requirements, current required 6+minimum employer contributions are 8-9%. Netherlands Arthrogen B.V. operates a defined contribution pension. All of its employees participate in the plan. All eligible employees receive an employer pension contribution and are also required to contribute. During the years ended December 31, 2019 and 2018, employer contributions to all plans were $604,294 and $440,368, respectively.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	15. Subsequent Events Except for the item disclosed in Note 8, there have been no subsequent events through the date these financial statements were issued.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Consolidation

The accompanying consolidated financial statements include the accounts of Meira Holdings and its wholly owned subsidiaries:

MeiraGTx Limited, a limited company under the laws of England and Wales (“Meira Limited”);

MeiraGTx, LLC, a Delaware corporation (“Meira LLC”);

MeiraGTx UK II Limited, (“Meira UK II”), a limited company under the laws of England and Wales;

Arthrogen, B.V., a Netherlands corporation (“Arthrogen”);

BRI-Alzan, Inc., a Delaware corporation (“BRI-Alzan”);

MeiraGTx B.V., a Netherlands corporation (“Meira BV”);

MeiraGTx Neurosciences, Inc. a Delaware corporation (“Meira Neuro”); and

MeiraGTx UK Limited (“Meira UK”), a limited company under the laws of England and Wales.

All intercompany balances and transactions between the consolidated companies have been eliminated in consolidation.

Use of Estimates

Cash and Cash Equivalents

Financial Instruments

Tax Incentive Receivable

Fair Value Measurements

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.

The table below represents the values of the Company's financial assets and liabilities that are required to be measured at fair value on a recurring basis:


	Fair Value Measurement Using:
			Significant		Significant Other		Significant
	December 31,		Observable Inputs		Observable Inputs		Unobservable
Description	2019		(Level 1)		(Level 2)		(Level 3)
Restricted cash	$	123,376	$	123,376	$	—	$	—
Asset retirement obligations	$	1,654,755	$	—	$	—	$	1,654,755


	Fair Value Measurement Using:
			Significant		Significant Other		Significant
	December 31,		Observable Inputs		Observable Inputs		Unobservable
Description	2018		(Level 1)		(Level 2)		(Level 3)
Restricted cash	$	123,376	$	123,376	$	—	$	—
Asset retirement obligations	$	128,119	$	—	$	—	$	128,119

The table below represents a summary of the changes in fair value of the Company’s Level 3 valuations from January 1, 2018 to December 31, 2019:


			Asset Retirement
	Warrant Liabilities		Obligations		Total
Balance as of January 1, 2018	$	2,679,633	$	178,419	$	2,858,052
Change in fair value		1,514,775		(99,090)		1,415,685
Exercise of warrants		(4,194,408)		—		(4,194,408)
Additional asset retirement obligations during the period		—		69,286		69,286
Amortization of interest		—		(38,301)		(38,301)
Effects of exchange rate		—		17,805		17,805
Balance as of December 31, 2018	$	—	$	128,119	$	128,119
Additional asset retirement obligations during the period		—		1,270,262		1,270,262
Amortization of interest		—		20,621		20,621
Change in fair value		—		255,999		255,999
Effects of exchange rate		—		(20,247)		(20,247)
Balance as of December 31, 2019	$	—	$	1,654,755	$	1,654,755

The fair values of the warrants were estimated using the Black-Scholes valuation model with the following assumptions:


	June 4, 2018		December 31, 2017
Risk-free interest rate	1.77	%	1.72	%
Expected volatility	80	%	80	%
Expected dividend yield	0		0
Expected life	1 day		9 months

The fair value of the Preferred Shares were based upon recent issuances of the Company’s Preferred Shares on or about those dates.

Concentrations of Credit Risk

Property, Plant and Equipment, Net

The estimated useful lives of the asset categories are as follows:


Asset Category		Useful Lives
Computer and office equipment		3 years
Laboratory equipment		5 years
Manufacturing equipment		7 years
Furniture and fixtures		5 years
Leasehold improvements		lesser of useful life or remaining term of lease

Expenditures for leasehold improvements are capitalized, and expenditures for maintenance and repairs are expensed to operations as incurred.

Leases

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.

Asset Retirement Obligations

Preferred Shares

Share-Based Compensation Expense

Options

The fair value of Ordinary Shares after the Company’s IPO was determined based upon the closing share price on the date of grant.

Restricted Shares

Collaboration Arrangements

Refer to the discussion in Note 10 for further information related to the accounting for the Collaboration Agreement.

Revenue Recognition

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

recognize revenue when (or as) the entity satisfies a performance obligation.

The Company’s collaboration revenue arrangements include the following:

Research and Development

Foreign Currencies

Income Taxes

The Company is required to estimate income taxes in each of the jurisdictions in which it operates.

Net Loss per Ordinary Share


	December 31,	December 31,
	2019	2018
Restricted Ordinary Shares subject to forfeiture	217,726	653,174
Share options	3,645,360	3,262,365
	3,863,086	3,915,539

Other Comprehensive Income (Loss)

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 License and Collaboration Agreement are generated in the United Kingdom.

The following table summarizes non-current assets by geographical area:


	December 31,		December 31,
	2019		2018
United States	$	14,354,792	$	454,568
United Kingdom		39,476,700		21,788,130
Netherlands		1,076,286		—
	$	54,907,778	$	22,242,698

Accounting Pronouncements Recently Adopted

Recent Accounting Pronouncements Not Yet Adopted

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Company's Financial Assets and Liabilities Measured at Fair Value

The table below represents the values of the Company's financial assets and liabilities that are required to be measured at fair value on a recurring basis:


	Fair Value Measurement Using:
			Significant		Significant Other		Significant
	December 31,		Observable Inputs		Observable Inputs		Unobservable
Description	2019		(Level 1)		(Level 2)		(Level 3)
Restricted cash	$	123,376	$	123,376	$	—	$	—
Asset retirement obligations	$	1,654,755	$	—	$	—	$	1,654,755


	Fair Value Measurement Using:
			Significant		Significant Other		Significant
	December 31,		Observable Inputs		Observable Inputs		Unobservable
Description	2018		(Level 1)		(Level 2)		(Level 3)
Restricted cash	$	123,376	$	123,376	$	—	$	—
Asset retirement obligations	$	128,119	$	—	$	—	$	128,119

Summary of the changes in fair value of the Company’s Level 3 valuations

The table below represents a summary of the changes in fair value of the Company’s Level 3 valuations from January 1, 2018 to December 31, 2019:


			Asset Retirement
	Warrant Liabilities		Obligations		Total
Balance as of January 1, 2018	$	2,679,633	$	178,419	$	2,858,052
Change in fair value		1,514,775		(99,090)		1,415,685
Exercise of warrants		(4,194,408)		—		(4,194,408)
Additional asset retirement obligations during the period		—		69,286		69,286
Amortization of interest		—		(38,301)		(38,301)
Effects of exchange rate		—		17,805		17,805
Balance as of December 31, 2018	$	—	$	128,119	$	128,119
Additional asset retirement obligations during the period		—		1,270,262		1,270,262
Amortization of interest		—		20,621		20,621
Change in fair value		—		255,999		255,999
Effects of exchange rate		—		(20,247)		(20,247)
Balance as of December 31, 2019	$	—	$	1,654,755	$	1,654,755

Fair Values of Warrants Estimated by Using Black-Scholes Valuation Model

The fair values of the warrants were estimated using the Black-Scholes valuation model with the following assumptions:


	June 4, 2018		December 31, 2017
Risk-free interest rate	1.77	%	1.72	%
Expected volatility	80	%	80	%
Expected dividend yield	0		0
Expected life	1 day		9 months

Schedule of Estimated Useful Lives of Assets

The estimated useful lives of the asset categories are as follows:


Asset Category		Useful Lives
Computer and office equipment		3 years
Laboratory equipment		5 years
Manufacturing equipment		7 years
Furniture and fixtures		5 years
Leasehold improvements		lesser of useful life or remaining term of lease

Schedule of Anti-dilutive Securities Excluded from Computation of Earnings per Share


	December 31,	December 31,
	2019	2018
Restricted Ordinary Shares subject to forfeiture	217,726	653,174
Share options	3,645,360	3,262,365
	3,863,086	3,915,539

Summary of Non-Current Assets by Geographical Area

The following table summarizes non-current assets by geographical area:


	December 31,		December 31,
	2019		2018
United States	$	14,354,792	$	454,568
United Kingdom		39,476,700		21,788,130
Netherlands		1,076,286		—
	$	54,907,778	$	22,242,698

Prepaid Expenses (Tables)

12 Months Ended

Dec. 31, 2019

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Summary of Prepaid Expenses

Prepaid expenses at December 31, 2019 and 2018 consist of the following:


	December 31,		December 31,
	2019		2018
Insurance	$	1,758,915	$	623,314
Clinical Trial Costs		1,609,166		373,723
Research and Development		239,161		352,658
Dues and License Fees		264,123		169,073
Rent		183,952		88,784
Other		408,768		330,233
	$	4,464,085	$	1,937,785

Property, Plant and Equipment, net (Tables)

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant and Equipment, net

Property, plant and equipment, net at December 31, 2019 and 2018 consist of the following:


	December 31,		December 31,
	2019		2018
Leasehold Improvements	$	17,557,316	$	11,652,055
Capitalized Leasehold Interest		—		7,150,611
Manufacturing Equipment		5,647,484		3,779,950
Laboratory Equipment		3,700,632		1,485,544
Computer and Office Equipment		1,066,984		334,525
Furniture & Fixtures		441,101		88,660
		28,413,517		24,491,345
Less: Accumulated depreciation		(4,555,409)		(2,477,108)
	$	23,858,108	$	22,014,237

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2019

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses at December 31, 2019 and 2018 were comprised of the following:


	December 31,		December 31,
	2019		2018
Compensation and Benefits	$	6,850,335	$	5,731,438
Clinical Trial Costs		7,788,077		4,013,094
Professional Fees		486,743		914,540
Consulting		1,247,989		821,009
Rent		283,876		122,770
Fixed Assets		1,108,362		—
Other		318,375		388,846
	$	18,083,757	$	11,991,697

Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

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


					Weighted-
			Weighted-		Average
			Average		Remaining
		Number of	Exercise		Contractual
		Options	Price		Life (years)
Outstanding at December 31, 2017		938,637	$	5.12
Granted		2,326,285		8.63
Exercised		—		—
Expired		—		—
Forfeited		(10,557)		(5.51)
Outstanding at December 31, 2018		3,254,365		7.64	9.24
Granted		3,645,360		17.94
Exercised		—		—
Expired		3,254,365		—
Forfeited		—		—
Outstanding at December 31, 2019		10,154,090	$	9.31	8.45
Options exercisable at December 31, 2019		1,437,281	$	7.30	7.89
Aggregate intrinsic value of options outstanding as of December 31, 2019	$	39,261,423
Aggregate intrinsic value of options exercisable as of December 31, 2019	$	18,278,490

Schedule of Grant Date Fair Values of the Stock Options Granted

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 (see Note 2):


	2019	2018
Risk-free interest rate	1.76 - 2.55%	2.32% - 2.84%
Expected volatility	90%	90%
Expected dividend yield	0%	0%
Expected life (in years)	5.5 - 6.1	5.5 - 9.5

Summary of Restricted Ordinary Shares


	Ordinary Shares	$ Value
Non-vested at December 31, 2017	105,913	$	865,861
Issued during 2018	1,306,348		19,595,220
Vested during 2018	(759,087)		(10,663,471)
Non-vested at December 31, 2018	653,174		9,797,610
Vested during 2019	(435,448)		(6,531,720)
Non-vested at December 31, 2019	217,726	$	3,265,890

Schedule of Share-Based Compensation Expense


	2019		2018
Research and development	$	5,059,046	$	3,372,054
General and administrative		10,869,924		14,511,500
Total share based compensation	$	15,928,970	$	17,883,554

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Summary of Net Operating Loss Carryforwards


	Federal		State
United States	$	27,552,418		27,493,036
United Kingdom	$	107,287,003		—
Netherlands	$	22,808,090		—

Schedule of Company's Pre Tax Earnings

The Company's pre tax earnings are as follows:


	December 31, 2019		December 31, 2018
United Kingdom	$	(37,993,537)	$	(73,359,978)
United States		(16,303,213)		(9,980,287)
Netherlands		(449,485)		—
	$	(54,746,235)	$	(83,340,265)

Schedule of Reconciliation of Income Tax Benefit with Amounts at the U.K. Statutory Income Tax Rate

The following table summarizes a reconciliation of income tax benefit compared with the amounts at the UK statutory income tax rate:


	December 31, 2019			December 31, 2018
Statutory rate	(10,401,785)	19.00	%	(15,834,650)	19.00	%
Permanent differences - other	(411,651)	0.75	%	1,438,934	(1.73)	%
RTP and other adjustment	3,068,999	(5.61)	%	387,509	(0.46)	%
State and local rate, net of federal tax	(2,041,097)	3.73	%	(1,159,522)	1.39	%
U.K. Tax credit	1,278,072	(2.33)	%	1,707,489	(2.05)	%
U.S. Tax credit	(1,257,481)	2.30	%	(436,250)	0.52	%
Foreign tax rate differential	(347,301)	0.63	%	(171,693)	0.21	%
UK Rate change (17% at exxpected DTA turn)	362,092	(0.66)	%	1,104,863	(1.33)	%
US state rate change	—	0.00	%	(6,496)	0.01	%
Change in valuation allowance	9,750,153	(17.81)	%	12,495,425	(14.99)	%
Actual income tax benefit effective tax rate	—	0.00	%	(474,391)	0.57	%

Schedule of Expense/(Benefit) for Income Taxes from Continuing Operations

The Expense/(Benefit) for income taxes from continuing operations consists of the following:


	December 31, 2019	December 31, 2018
Current Tax Expense/(Benefit)
United Kingdom	—	—
United States	—	—
Netherlands	—	—
Total Current	—	—
Deferred Tax Expense/(Benefit)
United Kingdom	(3,036,499)	(8,888,096)
United States	(6,631,936)	(3,606,275)
Netherlands	(81,718)	—
Total Deferred	(9,750,154)	(12,494,371)
Change in Valuation Allowance	9,750,154	12,019,980
Total Income Tax Expense/(Benefit)	—	(474,391)

Schedule of Deferred Tax Assets and Liabilities

Deferred Tax Assets/(Liabilities)


	December 31, 2019
	Total		UK		US		Netherlands
Deferred Tax Assets:
Net operating loss carryforwards	$	31,929,792	$	18,238,791	$	9,015,343	$	4,675,658
Lease Liability		6,012,466		1,704,357		4,308,109		—
Other		2,581,842		485,724		2,108,121		(12,003)
R&D Credit		2,635,188		244,051		2,391,137		—
Deferred tax assets		43,159,288		20,672,923		17,822,710		4,663,655

Deferred Tax Liabilities:
Indefinite-lived intangibles & Fixed Asset PPA		(173,431)		—		—		(173,431)
Right of use assets		(5,635,987)		(1,686,019)		(3,949,968)		—
Less: valuation allowance		(37,523,301)		(18,986,904)		(13,872,742)		(4,663,655)
Net deferred tax liability	$	(173,431)	$	—	$	—	$	(173,431)


	December 31, 2018
	Total		UK		US		Netherlands
Deferred Tax Assets:
Net operating loss carryforwards	$	20,646,185	$	15,997,008	$	4,645,856	$	3,321
Other		1,414,690		(46,604)		1,461,294		—
R&D Credit		1,133,656		—		1,133,656		—
Deferred tax assets		23,194,531		15,950,404		7,240,806		3,321
Less: valuation allowance		(23,194,531)		(15,950,404)		(7,240,806)		(3,321)
Net deferred tax asset	$	—	$	—	$	—	$	—

Related Party Transactions (Tables)

12 Months Ended

Dec. 31, 2019

Summary of the Deferred Revenue Recognition


Non-refundable upfront fee from Janssen	$	100,000,000
Deferred revenue recognized as license revenue during the year ended December 31, 2019		(13,291,956)
Effects of exchange rate		493,053
Deferred revenue at December 31, 2019	$	86,214,091

Schedule of Future Minimum Lease Payments Under Non-Cancellable Leases


	Operating Leases		Finance Leases
2020	$	3,555,287	$	26,451
2021		3,888,355		16,880
2022		3,955,076		12,660
2023		4,023,799		—
2024		3,826,294		—
Thereafter		10,708,509		—
Total undiscounted lease payments	$	29,957,320	$	55,991
Less: Imputed interest		(6,829,507)		(5,254)
Total lease liabilities	$	23,127,813	$	50,737

Incurred Charges Included in Loss from Operations

During the years ended December 31, 2019 and 2018, the Company incurred the following charges, which are included in loss from operations:


	2019		2018
Rent	$	576,404	$	557,698
Personnel		—		6,493
Other		—		6,334
Total charges incurred	$	576,404	$	570,525

July 2016 Lease [Member]

Schedule of Future Minimum Lease Payments Under Non-Cancellable Leases

The aggregate future minimum rental payments under this lease as of December 31, 2019 for years ending December 31 are as follows:


2020	$	554,432
2021		573,837
Total future rent payments	$	1,128,269

Lease Obligations (Tables)

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Schedule of Components of Lease Cost


Finance lease cost
Amortization of right-of-use assets	$	300,229
Interest on lease liabilities		2,409
Total Finance Lease Cost		302,638
Operating lease cost		2,384,048
Short-term lease cost		1,282,709
Total lease cost	$	3,969,395

Schedule of Condensed Consolidated Balance Sheets for Leases


Operating leases
Right of Use Asset	$	21,857,600
Capitalized Lease Obligations	$	23,127,813
Finance leases
Right-of-Use Asset	$	7,144,848
Capitalized Lease Obligations	$	50,737
Weighted-Average Remaining Lease Term
Operating leases		7.9	years
Finance leases		107.0	years
Weighted-Average Discount Rate
Operating Leases		8.5	%
Finance Leases		7.3	%

Schedule of Other Information Related to Leases


Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from finance leases	$	28,187
Operating cash flows from operating leases	$	1,246,169
Financing cash flows from finance leases	$	2,355

Right-of-use assets obtained in exchange for lease liabilities
Operating leases	$	23,279,980
Finance leases	$	44,629

Schedule of Future Minimum Lease Payments Under Non-Cancellable Leases


	Operating Leases		Finance Leases
2020	$	3,555,287	$	26,451
2021		3,888,355		16,880
2022		3,955,076		12,660
2023		4,023,799		—
2024		3,826,294		—
Thereafter		10,708,509		—
Total undiscounted lease payments	$	29,957,320	$	55,991
Less: Imputed interest		(6,829,507)		(5,254)
Total lease liabilities	$	23,127,813	$	50,737

Principal Business Activity - Additional Information (Details) - USD ($)				1 Months Ended	12 Months Ended
	Jan. 30, 2019	Jun. 07, 2018	Mar. 01, 2018	Jan. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Oct. 17, 2019
Schedule Of Description Of Business [Line Items]
Accumulated deficit					$ (203,035,952)	$ (148,289,717)
Cash flows from operations					20,044,897	(58,887,870)
Cash and cash equivalents					227,233,384	$ 68,080,175
Collaboration Option And License Agreement [Member] \| Janssen Pharmaceuticals Inc [Member]
Schedule Of Description Of Business [Line Items]
Upfront payment	$ 100,000,000			$ 100,000,000	$ 100,000,000
Minimum [Member] \| Collaboration Option And License Agreement [Member] \| JJDC [Member]
Schedule Of Description Of Business [Line Items]
Offsetting expense, period					12 months
Ordinary Shares [Member]
Schedule Of Description Of Business [Line Items]
Sale of ordinary shares in connection with public and private placement, net of issuance costs, shares		5,000,000	550,162
Ordinary shares, offering price		$ 15.00
Proceeds from issuance initial public offering net		$ 65,200,000
Arthrogen B.V. [Member]
Schedule Of Description Of Business [Line Items]
Equity acquired							100.00%

Summary of Significant Accounting Policies - Tax Incentive Receivable (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Tax incentive receivable	$ 11,974,437	$ 3,416,932
Other Current Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
VAT receivable	$ 1,800,000	$ 1,100,000

Summary of Significant Accounting Policies - Company's Financial Assets and Liabilities Measured at Fair Value (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Restricted Cash [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, net asset (liability)	$ 123,376	$ 123,376
Asset Retirement Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, net asset (liability)	1,654,755	128,119
Fair Value, Inputs, Level 1 [Member] \| Restricted Cash [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, net asset (liability)	123,376	123,376
Fair Value, Inputs, Level 3 [Member] \| Asset Retirement Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, net asset (liability)	$ 1,654,755	$ 128,119

Summary of Significant Accounting Policies - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Summary of the changes in fair value of the Company's Level 3 valuations
Balance ending	$ 128,119	$ 2,858,052
Change in fair value	255,999	1,415,685
Exercise of warrants		(4,194,408)
Additional asset retirement obligations during the period	1,270,262	69,286
Amortization of interest on asset retirement obligations	20,621	(38,301)
Effects of exchange rate	(20,247)	17,805
Balance beginning	1,654,755	128,119
Warrant Liabilities
Summary of the changes in fair value of the Company's Level 3 valuations
Balance ending		2,679,633
Change in fair value		1,514,775
Exercise of warrants		(4,194,408)
Asset Retirement Obligations
Summary of the changes in fair value of the Company's Level 3 valuations
Balance ending	128,119	178,419
Change in fair value	255,999	(99,090)
Additional asset retirement obligations during the period	1,270,262	69,286
Amortization of interest on asset retirement obligations	20,621	(38,301)
Effects of exchange rate	(20,247)	17,805
Balance beginning	$ 1,654,755	$ 128,119

Summary of Significant Accounting Policies - Additional Information (Details)		12 Months Ended
	Jan. 01, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 05, 2018 USD ($)
Change in fair value of warrants			$ 1,514,775
Exercise of warrants liability		$ 4,194,408	4,194,408
Liability for uncertainty in income taxes		0	0
Unrecognized tax benefits, income tax penalties and interest accrued		0
Reclassification from property and equipment of fully paid lease	$ 7,409,789
Discount rate	8.00%
Right-of-Use Asset		21,857,600
Lease obligations	$ 3,716,336
Capitalized Lease Obligations		$ 23,127,813
Measurement Input, Risk Free Interest Rate [Member]
Credit-adjusted risk-free rate		8
Accounting Standards Update 2016-02 [Member] \| Restatement Adjustment [Member]
Right-of-Use Asset		$ 10,836,319
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Warrant liability				$ 4,194,408
Change in fair value of warrants			$ 1,514,775

Summary of Significant Accounting Policies - Schedule of Change in Asset Retirement Obligations (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Asset Retirement Obligation [Abstract]
Balance at beginning of year	$ 128,119
Amortization of interest on asset retirement obligations	20,621	$ (38,301)
Effects of exchange rate	(20,247)	17,805
Balance at end of year	$ 1,654,755	$ 128,119

Summary of Significant Accounting Policies - Fair Values of Warrants Estimated by Using Black-Scholes Valuation Model (Details)		12 Months Ended
	Jun. 04, 2018	Dec. 31, 2017
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected life		9 months
Warrants [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Risk-free interest rate	1.77%	1.72%
Expected volatility	80.00%	80.00%
Expected dividend yield	0.00%	0.00%
Expected life	1 day

Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives of Assets (Details)	12 Months Ended
	Dec. 31, 2019
Computer Equipment And Software [Member]
Depreciation Amortization Impairment [Line Items]
Estimated useful life (years)	3 years
Laboratory Equipment [Member]
Depreciation Amortization Impairment [Line Items]
Estimated useful life (years)	5 years
Manufacturing Equipment [Member]
Depreciation Amortization Impairment [Line Items]
Estimated useful life (years)	7 years
Furniture & Fixtures [Member]
Depreciation Amortization Impairment [Line Items]
Estimated useful life (years)	5 years
Leasehold Improvements [Member]
Depreciation Amortization Impairment [Line Items]
Estimated useful life (years)	lesser of useful life or remaining term of lease

Summary of Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings per Share (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earning per share, amount	3,863,086	3,915,539
Restricted Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earning per share, amount	217,726	653,174
Share Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earning per share, amount	3,645,360	3,262,365

Summary of Significant Accounting Policies - Summary of Non-Current Assets by Geographical Area (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Operation By Geographical [Line Items]
Non-current assets	$ 54,907,778	$ 22,242,698
United States [Member]
Operation By Geographical [Line Items]
Non-current assets	14,354,792	454,568
United Kingdom [Member]
Operation By Geographical [Line Items]
Non-current assets	39,476,700	$ 21,788,130
Netherlands [Member]
Operation By Geographical [Line Items]
Non-current assets	$ 1,076,286

Acquisitions - Additional Information (Details)				12 Months Ended
Acquisitions - Additional Information (Details)	Oct. 17, 2019 EUR (€)	Oct. 17, 2019 USD ($)	Oct. 05, 2018 USD ($) shares	Dec. 31, 2019 USD ($)
Acquisition Date [Line Items]
Fair value of asset acquisition in process R&D \| $			$ 2,990,250
Contingent milestone payment \| $				$ 21,000,000
Vector Neurosciences Inc [Member]
Acquisition Date [Line Items]
Number of shares issued as initial merger consideration \| shares			225,000
Agreement date			Oct. 05, 2018
Period of shares issued as initial merger consideration			18 months
Vector Neurosciences Inc [Member] \| Maximum [Member]
Acquisition Date [Line Items]
Value of stockholders additional ordinary shares \| $			$ 21,000,000
Vector Neurosciences Inc [Member] \| Issued At Closing of Merger [Member]
Acquisition Date [Line Items]
Number of shares issued as initial merger consideration \| shares			202,500
Vector Neurosciences Inc [Member] \| Issued Following Closing of Merger [Member]
Acquisition Date [Line Items]
Number of shares issued as initial merger consideration \| shares			22,500
Arthrogen B.V. [Member]
Acquisition Date [Line Items]
Ownership percentage	100.00%	100.00%
Purchase price consideration	€ 500,000	$ 558,335
Acquisition related costs	€ 94,692	$ 105,740

Prepaid Expenses - Summary of Prepaid Expenses (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Insurance	$ 1,758,915	$ 623,314
Clinical Trial Costs	1,609,166	373,723
Research and Development	239,161	352,658
Dues and License Fees	264,123	169,073
Rent	183,952	88,784
Other	408,768	330,233
Total	$ 4,464,085	$ 1,937,785

Property, Plant and Equipment, net - Schedule of Property, Plant and Equipment, net (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 28,413,517	$ 24,491,345
Less: Accumulated depreciation	(4,555,409)	(2,477,108)
Property, plant and equipment, net	23,858,108	22,014,237
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	17,557,316	11,652,055
Capitalized Leasehold Interest [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		7,150,611
Manufacturing Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	5,647,484	3,779,950
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,700,632	1,485,544
Computer and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,066,984	334,525
Furniture & Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 441,101	$ 88,660

Property, Plant and Equipment, net - Additional Information (Details)		12 Months Ended
	Jan. 01, 2019 USD ($)	Dec. 31, 2019 USD ($) item	Dec. 31, 2018 USD ($)
Property, Plant and Equipment [Line Items]
Asset retirement obligations, discounted rate	8.00%
Asset retirement obligations	$ 3,736,404	$ 1,654,755	$ 128,119
Number of operating leases \| item		6
Depreciation expense		$ 2,238,560	2,053,220
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Asset retirement obligations		1,643,794
Computer and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Capital lease obligations		95,880	95,880
Accumulated depreciation		$ 95,880	$ 69,912

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Compensation and Benefits	$ 6,850,335	$ 5,731,438
Clinical Trial Costs	7,788,077	4,013,094
Professional Fees	486,743	914,540
Consulting	1,247,989	821,009
Rent	283,876	122,770
Fixed Assets	1,108,362
Other	318,375	388,846
Accrued Expenses	$ 18,083,757	$ 11,991,697

Notes Payable - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Oct. 26, 2017
Debt Instrument [Line Items]
Interest expense	$ 48,612	$ 33,429
ARE [Member]
Debt Instrument [Line Items]
Promissory note issued			$ 1,442,009
Promissory note rate of interest		5.00%
Promissory note expiration due date		Dec. 31, 2018
Repayment of promissory note		$ 1,472,433
Interest expense		$ 17,386

Share-Based Compensation - Additional Information (Details) - USD ($)				1 Months Ended	12 Months Ended
	Nov. 18, 2019	Jun. 07, 2018	Mar. 01, 2018	Jan. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term					P10Y
Shares reserved for issuance					4,150,461
Additional shares reserved for issuance				1,470,421
Shares available for future issuance					1,877,611
Weighted-average remaining contractual life of options, outstanding					8 years 5 months 12 days	9 years 2 months 27 days
Fair value of options Vested					$ 6,098,621	$ 1,387,607
Share options granted during the period					3,645,360	2,326,285
Share-based compensation					$ 15,928,970	$ 17,883,554
Total share-based compensation					15,928,970	17,883,554
Excess Tax Benefit from Share-based Compensation, Operating Activities					0	0
Excess Tax Benefit from Share-based Compensation, Financing Activities					0	0
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation					10,869,924	14,511,500
Ordinary Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ordinary shares awarded, per share		$ 15.00
Fully-diluted outstanding shares			3.00%
Share-based compensation			$ 3,096,104			6,456,215
Sale of ordinary shares in connection with public and private placement, net of issuance costs, shares		5,000,000	550,162
Ordinary Shares [Member] \| General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation						$ 3,096,104
Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ordinary shares		1,306,348				1,306,348
Ordinary shares forfeiture period							3 years
Ordinary shares awarded, per share		$ 15.00
Fully-diluted outstanding shares		5.00%
Share-based compensation					15,982,670	$ 20,141,876
Total share-based compensation					6,531,744	10,156,868
Restricted Shares [Member] \| General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation					9,450,926	$ 9,985,008
Restricted Shares [Member] \| Ordinary Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ordinary shares							867,935
Employee and Non Employee Board of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unvested options compensation expense					$ 16,398,970
Unvested options expected to be realized						4 years
Weighted average grant date fair value of options granted					$ 13.79	$ 6.53
Consultant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of ordinary shares in connection with public and private placement, net of issuance costs, shares	95,000
Shares issued, value	$ 1,372,750
Consultant [Member] \| Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ordinary shares awarded, per share					7.72
Employee [Member] \| Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ordinary shares awarded, per share					$ 7.76
Executive Officer [Member] \| Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance				505,000
Employee And Consultant [Member] \| Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance				1,117,000
First Anniversary [Member]
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 - Summary of Company's Share Option Activity Related to Employees, Non-Employee Members of the Board of Directors and Non-Employee Consultants (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of options, Beginning balance	3,254,365	938,637
Number of options, Granted	3,645,360	2,326,285
Number of options, Expired	3,254,365	0
Number of options, Forfeited		(10,557)
Number of options, Ending balance	10,154,090	3,254,365
Weighted-average exercise price, Beginning balance	$ 7.64	$ 5.12
Weighted-average remaining contractual life of options, outstanding	8 years 5 months 12 days	9 years 2 months 27 days
Weighted-average exercise price, Granted	$ 17.94	$ 8.63
Number of options, Options exercisable	1,437,281
Weighted-average remaining contractual life of options, exercisable	7 years 10 months 21 days
Weighted-average exercise price, Expired		0.00
Weighted-average exercise price, Forfeited		(5.51)
Weighted-average exercise price, Ending balance	$ 9.31	$ 7.64
Weighted-average exercise price, Option exercisable	$ 7.30
Aggregate intrinsic value, options outstanding	$ 39,261,423
Aggregate intrinsic value, options exercisable	$ 18,278,490

Share-Based Compensation - Schedule of Grant Date Fair Values of the Stock Option Granted Black-Scholes Valuation Model (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life of non-employee options (in years)			9 months
Employee and Non Employee Board of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, minimum	1.76%	2.32%
Risk-free interest rate, maximum	2.55%	2.84%
Expected volatility	90.00%	90.00%
Expected dividend yield	0.00%	0.00%
Minimum [Member] \| Employee and Non Employee Board of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life of non-employee options (in years)	5 years 6 months	5 years 6 months
Maximum [Member] \| Employee and Non Employee Board of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life of non-employee options (in years)	6 years 1 month 6 days	9 years 6 months

Share-Based Compensation - Summary of Restricted Ordinary Shares (Details) - Restricted Shares [Member] - USD ($)		12 Months Ended
	Jun. 07, 2018	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested Ordinary Shares, Beginning Balance		653,174	105,913
Issued, Ordinary Shares	1,306,348		1,306,348
Issued, Value			$ 19,595,220
Vested, Ordinary Shares		(435,448)	(759,087)
Non-vested Ordinary Shares, Ending Balance		217,726	653,174
Non-vested Value, Beginning Balance		$ 9,797,610	$ 865,861
Vested, Value		(6,531,720)	(10,663,471)
Non-vested Value, Ending Balance		$ 3,265,890	$ 9,797,610

Share-Based Compensation - Schedule of Share-Based Compensation Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Expense [Line Items]
Total share-based compensation	$ 15,928,970	$ 17,883,554
Research and Development Expenses [Member]
Share Based Compensation Expense [Line Items]
Total share-based compensation	5,059,046	3,372,054
General and Administrative Expense [Member]
Share Based Compensation Expense [Line Items]
Total share-based compensation	$ 10,869,924	$ 14,511,500

Ordinary Shares, Preferred Shares and Shareholders' Deficit - Additional Information (Details) - USD ($)											12 Months Ended
	Nov. 18, 2019	Aug. 07, 2019	Jul. 07, 2019	Mar. 21, 2019	Feb. 27, 2019	Oct. 05, 2018	Jun. 07, 2018	Jun. 05, 2018	Mar. 15, 2018	Mar. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2015
Offering costs											$ 7,497,852	$ 4,115,843
Common stock, shares issued											36,791,906	27,386,632
Gross proceeds from preferred shares												$ 56,849,594
Conversion of note payable into convertible preferred C shares												120,520,391
Preferred shares, purchase								3,600,000
Accretion of warrants issued in connection with convertible preferred shares												(1,045,500)
Change in fair value of warrant liability												1,514,775
Shares issued in exercise of warrants (in shares)								927,594
Preferred shares, value							$ 664,718					9,720,000
Proceeds from the sale of ordinary shares											$ 155,200,007	$ 69,750,000
Vector Neurosciences Inc [Member]
Number of shares issued as initial merger consideration						225,000
Period of shares issued as initial merger consideration						18 months
Vector Neurosciences Inc [Member] \| Issued At Closing of Merger [Member]
Number of shares issued as initial merger consideration						202,500
Vector Neurosciences Inc [Member] \| Issued Following Closing of Merger [Member]
Number of shares issued as initial merger consideration						22,500
License Agreement [Member]
Ordinary shares issued in connection with a license agreement											158,832
Restricted Shares [Member]
Ordinary shares, offering price							$ 15.00
Ordinary shares							1,306,348					1,306,348
Percentage of fully diluted shares							5.00%
Ordinary Shares [Member]
Sale of ordinary shares in connection with public and private placement, net of issuance costs, shares							5,000,000			550,162
Ordinary shares, offering price							$ 15.00
Proceeds from issuance initial public offering							$ 75,000,000
Offering costs							$ 9,807,622
Percentage of fully diluted shares										3.00%
Ordinary shares issued in connection with a license agreement				158,832							158,832
Number of options, Exercised											(134,533)
Conversion of note payable into convertible preferred C shares, shares							11,501,432				11,501,432	11,501,432
Conversion of note payable into convertible preferred C shares												$ 446
Ordinary Shares [Member] \| Restricted Shares [Member]
Ordinary shares													867,935
Preferred Shares [Member]
Sale of ordinary shares in connection with public and private placement, net of issuance costs, shares												5,425,124
Ordinary shares, offering price												$ 10.48
Offering costs												$ 690,475
Gross proceeds from preferred shares												56,849,611
Convertible Preferred C Shares [Member]
Offering costs												690,475
Accretion of warrants issued in connection with convertible preferred shares												$ 1,045,500
Convertible Preferred C Shares [Member] \| License Agreement [Member]
Sale of ordinary shares in connection with public and private placement, net of issuance costs, shares									13,360
Convertible Preferred C Shares [Member] \| Payments In Lieu [Member]
Sale of ordinary shares in connection with public and private placement, net of issuance costs, shares												129,419
Shares issued, value												$ 1,356,129
Vendor [Member]
Sale of ordinary shares in connection with public and private placement, net of issuance costs, shares			19,807
Shares issued, value			$ 421,500
Consultant [Member]
Sale of ordinary shares in connection with public and private placement, net of issuance costs, shares	95,000
Shares issued, value	$ 1,372,750
Consultant [Member] \| Restricted Shares [Member]
Ordinary shares, offering price											$ 7.72
IPO [Member]
Shares issued, value											$ 147,702,155	65,192,378
Offering costs												$ 9,807,622
Offering costs		$ 5,100,000
Common stock, shares issued		3,200,000
Proceeds from the sale of ordinary shares		$ 75,000,000
IPO [Member] \| Ordinary Shares [Member]
Sale of ordinary shares in connection with public and private placement, net of issuance costs, shares											8,997,102	5,000,000
Shares issued, value											$ 349	$ 194
Private Placement [Member]
Offering costs											$ 7,497,852
Offering costs					$ 2,400,000
Private Placement [Member] \| JJDC [Member]
Common stock, shares issued					2,898,550
Private Placement [Member] \| JJDC [Member] \| Collaboration Option And License Agreement [Member]
Common stock, shares issued					5,797,102
Proceeds from the sale of ordinary shares					$ 80,000,000

Income Taxes - Additional Information (Details) - USD ($)			12 Months Ended
	Apr. 01, 2020	Apr. 01, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes Disclosure [Line Items]
Income tax expense (benefit)				$ (474,391)
Foreign currency translation, tax			$ 0	474,391
Federal net operating loss carryforwards					$ 6,800,000
State net operating loss carryforwards					$ 6,700,000
Deferred tax assets, tax credit carryforwards, orphan drug and research and development			2,635,188	1,133,656
Provision for valuation allowance			0
Foreign currency translation, tax			$ 0	$ 474,391
Foreign tax rate differential				17.00%
Foreign tax rate differential		19.00%
Scenario, Forecast [Member]
Income Taxes Disclosure [Line Items]
Foreign tax rate differential	17.00%
Foreign tax rate differential	18.00%

Income Taxes - Net Operating Loss Carryforwards (Details)	Dec. 31, 2019 USD ($)
Federal [Member] \| United States [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 27,552,418
Federal [Member] \| United Kingdom [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	107,287,003
Federal [Member] \| Netherlands [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	22,808,090
State [Member] \| United States [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 27,493,036

Income Taxes - Summary of Company's Pre Tax Earnings (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Before Income Taxes [Line Items]
Total	$ (54,746,235)	$ (83,340,265)
Foreign Country [Member] \| Her Majesty's Revenue and Customs (HMRC) [Member] \| United Kingdom [Member]
Income Before Income Taxes [Line Items]
Total	(37,993,537)	(73,359,978)
Foreign Country [Member] \| Tax and Customs Administration, Netherlands [Member] \| Netherlands [Member]
Income Before Income Taxes [Line Items]
Total	(449,485)
Federal [Member] \| Internal Revenue Service (IRS) [Member] \| United States [Member]
Income Before Income Taxes [Line Items]
Total	$ (16,303,213)	$ (9,980,287)

Income Taxes - Summary of Reconciliation of Income Tax Benefit with Amounts at the U.K. Statutory Income Tax Rate (Details) - USD ($)		12 Months Ended
	Apr. 01, 2017	Dec. 31, 2019	Dec. 31, 2018
Change in valuation allowance		$ 9,750,154	$ 12,019,980
Total Income Tax Expense (Benefit)			(474,391)
Foreign tax rate differential	19.00%
Her Majesty's Revenue and Customs (HMRC) [Member]
Statutory rate		(10,401,785)	(15,834,650)
Permanent differences - other		(411,651)	1,438,934
RTP and other adjustments		3,068,999	387,509
State and local rate, net of federal tax		(2,041,097)	(1,159,522)
U.K. Tax credit		1,278,072	1,707,489
U.S. Tax credit		(1,257,481)	(436,250)
Foreign tax rate differential		(347,301)	(171,693)
UK Rate change (17% at expected DTA turn)		362,092	1,104,863
US state rate change			(6,496)
Change in valuation allowance		$ 9,750,153	12,495,425
Total Income Tax Expense (Benefit)			$ (474,391)
Statutory rate		19.00%	19.00%
Permanent differences-other		0.75%	(1.73%)
RTP and other adjustments		(5.61%)	(0.46%)
State and local rate, net of federal tax		3.73%	1.39%
U.K. Tax credit		(2.33%)	(2.05%)
U.S. Tax credit		2.30%	0.52%
Foreign tax rate differential		0.63%	0.21%
UK Rate Change (17% at expected DTA turn)		(0.66%)	(1.33%)
US state rate change		0.00%	0.01%
Change in valuation allowance		(17.81%)	(14.99%)
Actual income tax benefit effective tax rate		0.00%	0.57%

Income Taxes - Schedule of Expense/(Benefit) for Income Taxes from Continuing Operations (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Total Deferred	$ (9,750,154)	$ (12,494,371)
Change in Valuation Allowance	9,750,154	12,019,980
Total Income Tax Expense (Benefit)		(474,391)
United Kingdom [Member]
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Foreign	(3,036,499)	(8,888,096)
United States [Member]
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
United States	(6,631,936)	$ (3,606,275)
Netherlands [Member]
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Foreign	$ (81,718)

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets:
Net operating loss carryforwards	$ 31,929,792	$ 20,646,185
Lease Liability	6,012,466
Other	2,581,842	1,414,690
R&D Credit	2,635,188	1,133,656
Deferred tax assets	43,159,288	23,194,531
Less: valuation allowance	(37,523,301)	(23,194,531)
Deferred Tax Liabilities, Net [Abstract]
Indefinite-lived intangibles & Fixed Asset PPA	(173,431)
Right of use assets	(5,635,987)
Less: valuation allowance	(37,523,301)	(23,194,531)
Net deferred tax liability	(173,431)
Foreign Country [Member] \| United Kingdom [Member]
Deferred Tax Assets:
Net operating loss carryforwards	18,238,791	15,997,008
Lease Liability	1,704,357
Other	485,724	(46,604)
R&D Credit	244,051
Deferred tax assets	20,672,923	15,950,404
Less: valuation allowance	(18,986,904)	(15,950,404)
Deferred Tax Liabilities, Net [Abstract]
Right of use assets	(1,686,019)
Less: valuation allowance	(18,986,904)	(15,950,404)
Foreign Country [Member] \| Netherlands [Member]
Deferred Tax Assets:
Net operating loss carryforwards	4,675,658	3,321
Other	(12,003)
Deferred tax assets	4,663,655	3,321
Less: valuation allowance	(4,663,655)	(3,321)
Deferred Tax Liabilities, Net [Abstract]
Indefinite-lived intangibles & Fixed Asset PPA	(173,431)
Less: valuation allowance	(4,663,655)	(3,321)
Net deferred tax liability	(173,431)
Federal [Member] \| United States [Member]
Deferred Tax Assets:
Net operating loss carryforwards	9,015,343	4,645,856
Lease Liability	4,308,109
Other	2,108,121	1,461,294
R&D Credit	2,391,137	1,133,656
Deferred tax assets	17,822,710	7,240,806
Less: valuation allowance	(13,872,742)	(7,240,806)
Deferred Tax Liabilities, Net [Abstract]
Right of use assets	(3,949,968)
Less: valuation allowance	$ (13,872,742)	$ (7,240,806)

Related Party Transactions - Additional Information (Details)				1 Months Ended	12 Months Ended
	Jan. 30, 2019 USD ($)	Apr. 24, 2015	Feb. 04, 2015 Program	Jan. 30, 2019 USD ($)	Dec. 31, 2019 GBP (£) shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) shares	Oct. 31, 2020 GBP (£)	Oct. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) shares	Feb. 27, 2019 shares
Related Party Transaction [Line Items]
Deferred revenue recognized as license revenue during the year ended December 31, 2019						$ 13,291,956
Revenue recognized						$ 27,296,062
Deferred research funding, amortization period					8 months	8 months
Common stock, shares issued \| shares					36,791,906		27,386,632			36,791,906
Issuance of ordinary shares in connection with a license agreement, shares \| shares						$ 1,966,340
Amount due under services agreement							$ 0			$ 0
Related party transaction amounts of work orders issued						576,404	570,525
Research and development expenses						$ 24,875,659	33,620,223
Operating lease expiration date					Dec. 31, 2021	Dec. 31, 2021
Operating lease rent expenses							487,555
Operating lease rent expenses						$ 487,555
Letter of credit, secured with restricted cash							$ 123,676			$ 123,676
Transition Services Agreement with Related Party [Member] \| Kadmon [Member]
Related Party Transaction [Line Items]
Percentage of administrative fees		7.00%
Services termination date		Apr. 24, 2018
Ownership percentage by related party					5.80%		12.90%			5.80%
Cash payment						576,404	$ 1,431,555
Research Agreement [Member]
Related Party Transaction [Line Items]
Amount due under services agreement							389,101
Collaboration Option And License Agreement [Member] \| Janssen Pharmaceuticals Inc [Member]
Related Party Transaction [Line Items]
Upfront payment	$ 100,000,000			$ 100,000,000		100,000,000
Deferred revenue recognized as license revenue during the year ended December 31, 2019						(13,291,956)
Deferred revenue										$ 86,214,091
Clinical Collaborative Arrangement [Member] \| Janssen Pharmaceuticals Inc [Member]
Related Party Transaction [Line Items]
Percentage of costs payable on annual net sales of licensed product statement				100.00%
Percentage of royalties payable on annual net sales of licensed product statement				20.00%
Proceeds from development and commercial milestone payments				$ 340,000,000
Collaboration Agreement [Member] \| Janssen Pharmaceuticals Inc [Member]
Related Party Transaction [Line Items]
Deferred revenue										658,667
Collaboration Agreement [Member] \| Research and Development Expenses [Member] \| Janssen Pharmaceuticals Inc [Member]
Related Party Transaction [Line Items]
Amortized of deferred research funding						$ 444,399
Research Collaborative Arrangement [Member] \| Janssen Pharmaceuticals Inc [Member]
Related Party Transaction [Line Items]
Percentage of costs payable on annual net sales of licensed product statement				100.00%
License Agreement [Member]
Related Party Transaction [Line Items]
License Agreement Amendment Description					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; (b) ACHM caused by mutations in CNGA3; (c) X-linked retinitis pigmentosa ("XLRP"); and (d) RPE65-mediated IRD.	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; (b) ACHM caused by mutations in CNGA3; (c) X-linked retinitis pigmentosa ("XLRP"); and (d) RPE65-mediated IRD.
License arrangement upfront payment					£ 1,500,000	$ 1,976,000
Issuance of ordinary shares in connection with a license agreement, shares \| shares					1,500,000	1,966,000
Payments for research and development expenses agreement						4,271,275	325,431
Research and development expenses						3,942,000
July 2016 Lease [Member]
Related Party Transaction [Line Items]
Deferred rent							201,264
Amortization Stage Two [Member] \| Collaboration Agreement [Member] \| Research and Development Expenses [Member] \| Janssen Pharmaceuticals Inc [Member]
Related Party Transaction [Line Items]
Deferred revenue										328,524
Private Placement [Member] \| JJDC [Member]
Related Party Transaction [Line Items]
Common stock, shares issued \| shares											2,898,550
Private Placement [Member] \| Collaboration Option And License Agreement [Member] \| JJDC [Member]
Related Party Transaction [Line Items]
Common stock, shares issued \| shares											5,797,102
UCL Consultants Limited [Member] \| Research Agreement [Member]
Related Party Transaction [Line Items]
Amount due under services agreement										166,404
Research and development expenses						306,000	$ 636,000
UCL Consultants Limited [Member] \| Scenario, Forecast [Member] \| Research Agreement [Member]
Related Party Transaction [Line Items]
Future obligations under agreement								£ 165,878	$ 218,000
UCL Business, PLC [Member] \| License Agreements Effective March 15, 2018 [Member] \| License Agreement [Member]
Related Party Transaction [Line Items]
Sales milestone payments					39,800,000					52,400,000
Number of collaborations programs \| Program			8
Maintenance fee					£ 50,000	$ 66,000
July 2016 Lease [Member]
Related Party Transaction [Line Items]
Operating leases rent expense payment description					The Company records monthly rent expense on a straight-line basis from July 1, 2016 through December 31, 2021.	The Company records monthly rent expense on a straight-line basis from July 1, 2016 through December 31, 2021.
Deferred rent										153,146
Letter of credit outstanding amount										122,866
July 2016 Lease [Member] \| July 2016 Lease [Member]
Related Party Transaction [Line Items]
Aggregate future minimum rental payments under operating lease										$ 1,128,269

Related Party Transactions - Revenue Recognition (Details) - USD ($)		1 Months Ended	12 Months Ended
	Jan. 30, 2019	Jan. 30, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Deferred revenue recognized as license revenue during the year ended December 31, 2019			$ 13,291,956
Janssen Pharmaceuticals Inc [Member] \| Collaboration Option And License Agreement [Member]
Related Party Transaction [Line Items]
Non-refundable upfront fee from Janssen	$ 100,000,000	$ 100,000,000	100,000,000
Deferred revenue recognized as license revenue during the year ended December 31, 2019			(13,291,956)
Effects of exchange rate			493,053
Deferred revenue			$ 86,214,091

Related Party Transactions - Schedule of Future Minimum Rental Payments (Details)	Dec. 31, 2019 USD ($)
2020	$ 3,555,287
2021	3,888,355
Total undiscounted lease payments	29,957,320
July 2016 Lease [Member]
2020	554,432
2021	573,837
Total undiscounted lease payments	$ 1,128,269

Related Party Transactions - Incurred Charges included in Loss from Operations (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Total charges incurred	$ 576,404	$ 570,525
Rent [Member]
Related Party Transaction [Line Items]
Total charges incurred	$ 576,404	557,698
Personnel [Member]
Related Party Transaction [Line Items]
Total charges incurred		6,493
Other [Member]
Related Party Transaction [Line Items]
Total charges incurred		$ 6,334

Related Party Transactions - Performance Obligation (Details) - Research Collaborative Arrangement [Member] - Janssen Pharmaceuticals Inc [Member] - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01	Dec. 31, 2019 USD ($)
Related Party Transaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 86,214,091
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	5 years 6 months

Lease Obligations - Additional Information (Details)	9 Months Ended	12 Months Ended
Lease Obligations - Additional Information (Details)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 GBP (£)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 GBP (£)	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Jul. 31, 2019 GBP (£)
Lessee, Lease, Description [Line Items]
Short term lease commitments						$ 52,000
ROU asset						21,857,600
Operating lease liability						23,127,813
Operating leases	$ 23,279,980
Operating lease cash payments	$ 1,246,169
Operating lease rent expenses			$ 487,555
Rent expense under operating lease agreements					$ 487,555
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lease term		3 years	3 years
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lease term		108 years	108 years
New York Sublease [Member]
Lessee, Lease, Description [Line Items]
ROU asset						11,800,000
Operating lease liability						11,800,000
Operating lease rent expenses			$ 1,110,847
Tudor Street Lease [Member]
Lessee, Lease, Description [Line Items]
ROU asset \| £		£ 1,200,000
Operating lease liability						1,500,000
Operating lease cash payments		127,800	168,000
Operating lease rent expenses		£ 82,149	$ 108,000
Option to terminate		The Company has the right to terminate this lease on June 10, 2024 by giving the landlord notice at least six months prior to such date.	The Company has the right to terminate this lease on June 10, 2024 by giving the landlord notice at least six months prior to such date.
Provost Street Lease [Member]
Lessee, Lease, Description [Line Items]
Operating lease cash payments		£ 0	$ 180,000
Operating lease rent expenses		£ 238,222	$ 314,000
Option to terminate		The Company has the right to terminate this lease on September 8, 2024 by giving the landlord notice at least six months prior to such date.	The Company has the right to terminate this lease on September 8, 2024 by giving the landlord notice at least six months prior to such date.
Provost Street Lease [Member] \| Minimum [Member]
Lessee, Lease, Description [Line Items]
ROU asset \| £		£ 4,900,000
Operating lease liability \| £		4,900,000
Provost Street Lease [Member] \| Maximum [Member]
Lessee, Lease, Description [Line Items]
ROU asset						6,500,000
Operating lease liability						6,500,000
Ebenezer Street Leases [Member]
Lessee, Lease, Description [Line Items]
ROU asset						2,300,000	£ 1,700,000
Operating lease liability		1,700,000				$ 2,300,000
Operating lease cash payments		274,969	$ 362,000	£ 137,485	169,000
Operating lease rent expenses		£ 274,969	$ 362,000
Rent expense under operating lease agreements				£ 137,485	$ 169,000

Lease Obligations - Schedule of Components of Lease Cost (Details)	9 Months Ended
	Sep. 30, 2019 USD ($)
Finance Lease Costs [Abstract]
Amortization of right-of-use assets	$ 300,229
Interest on lease liabilities	2,409
Total Finance Lease Cost	302,638
Operating lease cost	2,384,048
Short-term lease cost	1,282,709
Total lease Cost	$ 3,969,395

Lease Obligations - Schedule of Condensed Consolidated Balance Sheets for Leases (Details)	Dec. 31, 2019 USD ($)
Leases [Abstract]
Right-of-Use Asset	$ 21,857,600
Capitalized Lease Obligations	$ 23,127,813
Operating Lease, Liability, Statement of Financial Position [Extensible List]	mgtx:LeaseObligationsCurrent mgtx:LeaseObligationsNonCurrent
Right-of-Use Asset	$ 7,144,848
Capitalized Lease Obligations	$ 50,737
Operating leases	7 years 10 months 24 days
Finance leases	107 years
Operating leases	8.50%
Finance leases	7.30%

Lease Obligations - Schedule of Other Information Related to Leases (Details)	9 Months Ended
	Sep. 30, 2019 USD ($)
Leases [Abstract]
Operating cash flows from finance leases	$ 28,187
Operating lease cash payments	1,246,169
Financing cash flows from finance leases	2,355
Operating leases	23,279,980
Finance leases	$ 44,629

Lease Obligations - Schedule of Future Minimum Lease Payments Under Non-Cancellable Leases (Details)	Dec. 31, 2019 USD ($)
Operating Leases
2020	$ 3,555,287
2021	3,888,355
2022	3,955,076
2023	4,023,799
2024	3,826,294
Thereafter	10,708,509
Total undiscounted lease payments	29,957,320
Less: Imputed interest	(6,829,507)
Operating lease liability	23,127,813
Finance Leases
2020	26,451
2021	16,880
2022	12,660
Total undiscounted lease payments	55,991
Less: Imputed interest	(5,254)
Finance lease liability	$ 50,737

Commitments - Additional Information (Details)										1 Months Ended			12 Months Ended
Commitments - Additional Information (Details)	Mar. 25, 2021 USD ($)	Jun. 07, 2018 $ / shares shares	Mar. 01, 2018	Aug. 24, 2017 USD ($)	Dec. 05, 2016 USD ($) shares	Mar. 22, 2016 USD ($)	Sep. 28, 2015 $ / shares shares	Apr. 24, 2015 $ / shares shares	Feb. 04, 2015 Program	Jan. 31, 2018 USD ($)	Feb. 14, 2017 USD ($)	Apr. 30, 2015 USD ($)	Dec. 31, 2019 EUR (€) shares	Dec. 31, 2019 GBP (£) shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 EUR (€) shares	Dec. 31, 2018 USD ($) shares	Jan. 31, 2018	Dec. 31, 2017 USD ($)	Dec. 31, 2015	Dec. 31, 2019 GBP (£)	Dec. 31, 2019 USD ($)	Dec. 05, 2019 USD ($)	Jan. 01, 2016 USD ($)
Other Commitments [Line Items]
Rent expense under operating lease agreements																	$ 487,555
Operating lease termination date													Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2021
Research and development expenses															$ 24,875,659		33,620,223
General and administrative expense															$ 46,684,297		$ 44,483,938
Ordinary share \| shares													3,645,360	3,645,360	3,645,360	2,326,285	2,326,285
Common Class B [Member]
Other Commitments [Line Items]
Employees share award \| shares								193
Service Agreements [Member]
Other Commitments [Line Items]
Employees aggregate compensation \| €													€ 300,000
Research and development expenses													944,500		$ 1,234,000	€ 1,001,000	$ 1,334,000
Future obligations under agreement													157,000									$ 207,000
Employment Agreements [Member]
Other Commitments [Line Items]
Employees aggregate compensation										$ 710,000
Future obligations under agreement																						2,418,750
Aggregate discretionary bonus										$ 1,196,000					5,403,000		3,415,000		$ 850,000
Employee agreement description										The employment agreements also provide for an annual guaranteed cash bonus targeted at 100% of annual compensation. The agreements also provide for discretionary annual performance bonuses targeted to be not less than 50-60% of the employee's base salary and grants of restricted shares.
Employment agreement term																		3 years
Percentage of fully-diluted outstanding shares		5.00%	3.00%
Consulting And Other Agreements [Member]
Other Commitments [Line Items]
General and administrative expense															0		263,970
Research Agreement One [Member]
Other Commitments [Line Items]
Research and development expenses															92,657		$ 418,000
Consulting agreement term						5 years
Quarterly payment received for research and development agreement						$ 104,500
License Agreement [Member]
Other Commitments [Line Items]
Research and development expenses															3,942,000
Restricted Shares [Member]
Other Commitments [Line Items]
Employees share award \| shares		1,306,348														1,306,348	1,306,348
Employees share award, per share \| $ / shares		$ 15.00
Ordinary shares forfeiture period																				3 years
Restricted Shares [Member] \| Service Agreements [Member]
Other Commitments [Line Items]
Employees share award \| shares								696,933
Employees share award, per share \| $ / shares								$ 7.76
Ordinary shares forfeiture period								3 years
Restricted Shares [Member] \| Consulting And Other Agreements [Member]
Other Commitments [Line Items]
Employees share award \| shares							170,809
Ordinary shares forfeiture period							3 years
Restricted Shares [Member] \| Director [Member] \| Consulting And Other Agreements [Member]
Other Commitments [Line Items]
Consulting agreement term							3 years
Maximum [Member] \| Service Agreements [Member]
Other Commitments [Line Items]
Employees aggregate compensation													€ 430,000		$ 566,000
Maximum [Member] \| Employment Agreements [Member]
Other Commitments [Line Items]
Employees aggregate compensation										$ 1,075,000
Percentage of fully-diluted outstanding shares													8.00%	8.00%	8.00%
General and Administrative Expense [Member] \| Restricted Shares [Member] \| Consulting And Other Agreements [Member]
Other Commitments [Line Items]
Employees share award, per share \| $ / shares							$ 7.72
U.S. Department Of Health And Human Services [Member] \| Research Agreement [Member]
Other Commitments [Line Items]
Research and development expenses															$ 117,592		$ 111,938
Quarterly payment received for research and development agreement												$ 21,250
Cornell University [Member] \| Research Agreement [Member]
Other Commitments [Line Items]
Research and development expenses															20,613		143,073
Future obligations under agreement																							$ 206,984
Agreement amended date					Jun. 12, 2017
Research and collaboration agreement period					3 years
Ordinary share \| shares					6,441
Research and collaboration agreement period											1 year
Research and collaboration agreement amount											$ 679,473
Cornell University [Member] \| Issued At Closing of Merger [Member] \| Research Agreement [Member]
Other Commitments [Line Items]
Research and development expenses					$ 17,000										1,756,487		1,625,152
Cornell University [Member] \| Issued Following Closing of Merger [Member] \| Research Agreement [Member]
Other Commitments [Line Items]
Research and development amended agreement amount				$ 182,520
National Institutes of Health [Member] \| License Agreement [Member]
Other Commitments [Line Items]
Research and development expenses															60,000		50,000
BRI-Alzan [Member] \| License Agreement [Member]
Other Commitments [Line Items]
Research and development expenses															15,000		$ 15,000
Sales milestone payments																								$ 4,500,000
Scenario, Forecast [Member] \| U.S. Department Of Health And Human Services [Member] \| Research Agreement [Member]
Other Commitments [Line Items]
Future obligations under agreement	$ 106,250
Agreement expiration date	Mar. 25, 2021
License Agreements Effective March 15, 2018 [Member] \| UCL Business, PLC [Member] \| License Agreement [Member]
Other Commitments [Line Items]
Number of collaborations programs \| Program									8
Sales milestone payments																					£ 39,800,000	$ 52,400,000
Maintenance fee														£ 50,000	$ 66,000

Employee Benefit Plans - Additional Information (Details) - USD ($)			12 Months Ended
	Jan. 01, 2017	Aug. 01, 2016	Dec. 31, 2020	Dec. 31, 2019
United States [Member]
Compensation And Retirement Disclosure [Line Items]
Defined contribution plan, annual contributions per employee, percent	6.00%
United States [Member] \| Minimum [Member]
Compensation And Retirement Disclosure [Line Items]
Defined contribution plan, employee eligibility age	21 years
United Kingdom. [Member]
Compensation And Retirement Disclosure [Line Items]
Defined benefit plan, plan assets, contributions by employer			$ 440,368	$ 604,294
United Kingdom. [Member] \| Minimum [Member]
Compensation And Retirement Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percent		7.50%		8.00%
United Kingdom. [Member] \| Maximum [Member]
Compensation And Retirement Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percent		10.00%		9.00%