Principal Business Activity	12 Months Ended
Dec. 31, 2021
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: ocular diseases, including inherited retinal diseases as well as large degenerative ocular 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. Additionally, on August 4, 2020, the Company entered into agreements to acquire the buildings for its second cGMP viral vector manufacturing facility and its first cGMP plasmid and DNA production facility in Shannon, Ireland to expand its manufacturing and supply chain capabilities. The Company closed on the acquisition of the first building in August 2020 and closed on the acquisition of the second building in January 2021. Acquisitions On October 4, 2021, the Company acquired Bullseye Therapeutics, Inc. (“Bullseye”), a company engaged in developing mechanisms to deliver retinal drugs and gene therapies to the eye. Bullseye was renamed MeiraGTx Therapeutics, Inc. On April 9, 2020, the Company acquired Emrys Bio Inc. (“Emrys”), a pre-clinical biopharmaceutical company developing brain-derived neurotrophic factor gene therapy for treatment of genetic obesity disorders, as well as the development of gene therapy product candidates for other central nervous system diseases. Emrys was renamed MeiraGTx Bio, Inc. These acquisitions are 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, 2021 totaled $340.6 million, and management expects to incur substantial losses in future periods. The success of the Company is subject to certain risks and uncertainties, including among others, uncertainty of product development; competition in the Company’s field of use; uncertainty of capital availability; uncertainty in the Company’s ability to enter into agreements with collaborative partners; expanding and protecting the Company’s intellectual property portfolio; dependence on third parties; dependence on key personnel; the COVID-19 pandemic and mitigation measures. For the year ended December 31, 2021, the Company used $10.5 million in cash flows from operations and there are no assurances that the Company will generate positive cash flows in the future. Additionally, there are no assurances that the Company will be successful in obtaining an adequate level of financing for the development and commercialization of its product candidates. As of December 31, 2021, the Company had cash and cash equivalents in the amount of $137.7 million, which consisted of depository and money market 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 $100.0 million in March 2019 and a $30.0 million milestone payment in December 2021. The Company also receives funding for certain research, manufacturing, clinical development and commercialization costs, potential additional milestone payments upon the achievement of such milestones and royalties on future net sales of products. The Company estimates that its cash and cash equivalents on hand and accounts receivable – related party at December 31, 2021 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. There are also many uncertainties regarding the pandemic caused by the novel coronavirus, or COVID-19, and the Company continues to monitor the impact of the pandemic on all aspects of its business, including how the pandemic will impact its financial condition, liquidity, operations, clinical studies, employees, vendors, and industry. While the pandemic did not materially affect the Company's financial results and business operations in the year ended December 31, 2021 and 2020, the Company is unable to predict the impact that COVID-19 will have on its financial position and operating results in future periods due to numerous uncertainties. The Company will continue to assess the evolving impact of the COVID-19 pandemic and will make adjustments to its operations as necessary. The Company’s capital resources and operations to date have been funded primarily with the proceeds from the Collaboration Agreement and private and public equity offerings. In the future, the Company may seek to raise additional capital through equity offerings, debt financings, marketing and distribution arrangements and other collaborations, strategic alliances and licensing arrangements or other sources to enable it to complete the development and potential commercialization of its product candidates. The COVID-19 outbreak and mitigation measures also have had, and may continue to have, an adverse impact on global economic conditions, which could have an adverse effect on the Company’s ability to raise capital when needed.

Principal Business Activity

12 Months Ended

Dec. 31, 2021

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: ocular diseases, including inherited retinal diseases as well as large degenerative ocular 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. Additionally, on August 4, 2020, the Company entered into agreements to acquire the buildings for its second cGMP viral vector manufacturing facility and its first cGMP plasmid and DNA production facility in Shannon, Ireland to expand its manufacturing and supply chain capabilities. The Company closed on the acquisition of the first building in August 2020 and closed on the acquisition of the second building in January 2021.

Acquisitions

On October 4, 2021, the Company acquired Bullseye Therapeutics, Inc. (“Bullseye”), a company engaged in developing mechanisms to deliver retinal drugs and gene therapies to the eye. Bullseye was renamed MeiraGTx Therapeutics, Inc.

On April 9, 2020, the Company acquired Emrys Bio Inc. (“Emrys”), a pre-clinical biopharmaceutical company developing brain-derived neurotrophic factor gene therapy for treatment of genetic obesity disorders, as well as the development of gene therapy product candidates for other central nervous system diseases. Emrys was renamed MeiraGTx Bio, Inc.

These acquisitions are 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, 2021 totaled $340.6 million, and management expects to incur substantial losses in future periods. The success of the Company is subject to certain risks and uncertainties,

including among others, uncertainty of product development; competition in the Company’s field of use; uncertainty of capital availability; uncertainty in the Company’s ability to enter into agreements with collaborative partners; expanding and protecting the Company’s intellectual property portfolio; dependence on third parties; dependence on key personnel; the COVID-19 pandemic and mitigation measures. For the year ended December 31, 2021, the Company used $10.5 million in cash flows from operations and there are no assurances that the Company will generate positive cash flows in the future. Additionally, there are no assurances that the Company will be successful in obtaining an adequate level of financing for the development and commercialization of its product candidates.

As of December 31, 2021, the Company had cash and cash equivalents in the amount of $137.7 million, which consisted of depository and money market 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 $100.0 million in March 2019 and a $30.0 million milestone payment in December 2021. The Company also receives funding for certain research, manufacturing, clinical development and commercialization costs, potential additional milestone payments upon the achievement of such milestones and royalties on future net sales of products. The Company estimates that its cash and cash equivalents on hand and accounts receivable – related party at December 31, 2021 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.

There are also many uncertainties regarding the pandemic caused by the novel coronavirus, or COVID-19, and the Company continues to monitor the impact of the pandemic on all aspects of its business, including how the pandemic will impact its financial condition, liquidity, operations, clinical studies, employees, vendors, and industry. While the pandemic did not materially affect the Company's financial results and business operations in the year ended December 31, 2021 and 2020, the Company is unable to predict the impact that COVID-19 will have on its financial position and operating results in future periods due to numerous uncertainties. The Company will continue to assess the evolving impact of the COVID-19 pandemic and will make adjustments to its operations as necessary.

The Company’s capital resources and operations to date have been funded primarily with the proceeds from the Collaboration Agreement and private and public equity offerings. In the future, the Company may seek to raise additional capital through equity offerings, debt financings, marketing and distribution arrangements and other collaborations, strategic alliances and licensing arrangements or other sources to enable it to complete the development and potential commercialization of its product candidates. The COVID-19 outbreak and mitigation measures also have had, and may continue to have, an adverse impact on global economic conditions, which could have an adverse effect on the Company’s ability to raise capital when needed.