Basis of presentation	12 Months Ended
Dec. 31, 2019
Basis of presentation
Basis of Presentation	2. Basis of presentation The accompanying financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”), or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial statements upon adoption. Under the Jumpstart Our Business Startups Act of 2012, as amended (“the JOBS Act”), the Company meets the definition of an emerging growth company, and has elected the extended transition period for complying with new or revised accounting standards, which delays the adoption of these accounting standards until they would apply to private companies. Recently adopted accounting pronouncements In May 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, which amends the guidance for accounting for revenue from contracts with customers. This ASU supersedes the revenue recognition requirements in ASC Topic 605, Revenue Recognition, (“ASC 605”), and creates a new topic, ASC 606, Revenue from Contracts with Customers. Through subsequent targeted amendments, the FASB issued additional ASUs that delayed the effective date of ASC 606 and clarified various aspects of the new revenue guidance, including principal versus agent considerations, identifying performance obligations, licensing, and other improvements and practical expedients. The Company adopted this new standard on January 1, 2019 using the modified retrospective transition method. The Company presents revenue from contracts with customers as collaboration revenue in the Company’s statements of operations. The Company applied this new standard to all contracts with customers that were not complete as of the adoption date and has determined that no cumulative catch-up adjustment to accumulated deficit was required. See Note 4, “Research collaboration agreement with Allergan” for additional information regarding the Company’s single contract that falls within the scope of ASC 606. The Company considered the adoption of ASC 606 compared to what would have been recognized by the Company under the prior revenue standard, ASC 605. The adoption of ASC 606 did not have a material impact on the Company’s financial statements as of and for the year ended December 31, 2019. The Company has determined that the accounting for the Company’s various grant agreements is outside the scope of ASC 606, as the government agencies granting the Company funds are not receiving reciprocal value for their contributions. There are currently no grants outstanding in 2019. Since the accounting for government grants falls outside the scope of ASC 606, the Company has reclassified the grant income earned in 2018 separate and apart from revenue earned from contracts with customers in the Company’s statements of operations to conform to the current year presentation. In June 2018, the FASB issued ASU 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. This ASU expands the scope of Topic 718, Compensation—Stock Compensation to include share-based payments issued to nonemployees for goods or services. Under the new guidance, the existing employee guidance will apply to nonemployee share based transactions (as long as the transaction is not effectively a form of financing), with the exception of specific guidance related to the attribution of compensation cost. The cost of nonemployee awards will continue to be recorded as if the grantor had paid cash for the goods or services. The new accounting guidance will be effective for the Company on January 1, 2020. The Company has early adopted this new standard on January 1, 2019. The adoption did not have a material impact on the Company’s financial statements. Recently issued accounting pronouncements In February 2016, the FASB issued ASU No. 2016‑02, Leases (“ASC 842”), which requires a lessee to recognize assets and liabilities on the balance sheet for operating leases and changes many key definitions, including the definition of a lease. The new standard includes a short‑term lease exception for leases with a term of 12 months or less, as part of which a lessee can make an accounting policy election not to recognize lease assets and lease liabilities. Lessees will continue to differentiate between finance leases (previously referred to as capital leases) and operating leases using classification criteria that are substantially similar to the previous guidance. The new standard will be effective for the Company in fiscal years beginning after December 15, 2020, and early adoption is permitted. The Company anticipates that the adoption of this standard will have an impact on its balance sheet due to the recognition of right-of-use assets and lease liabilities; however, the Company is currently evaluating the impact that the adoption of ASC 842 will have on its financial statements.

2. Basis of presentation

The accompanying financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”), or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial statements upon adoption. Under the Jumpstart Our Business Startups Act of 2012, as amended (“the JOBS Act”), the Company meets the definition of an emerging growth company, and has elected the extended transition period for complying with new or revised accounting standards, which delays the adoption of these accounting standards until they would apply to private companies.

Recently adopted accounting pronouncements

In May 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, which amends the guidance for accounting for revenue from contracts with customers. This ASU supersedes the revenue recognition requirements in ASC Topic 605, Revenue Recognition, (“ASC 605”), and creates a new topic, ASC 606, Revenue from Contracts with Customers. Through subsequent targeted amendments, the FASB issued additional ASUs that delayed the effective date of ASC 606 and clarified various aspects of the new revenue guidance, including principal versus agent considerations, identifying performance obligations, licensing, and other improvements and practical expedients. The Company adopted this new standard on January 1, 2019 using the modified retrospective transition method. The Company presents revenue from contracts with customers as collaboration revenue in the Company’s statements of operations. The Company applied this new standard to all contracts with customers that were not complete as of the adoption date and has determined that no cumulative catch-up adjustment to accumulated deficit was required. See Note 4, “Research collaboration agreement with Allergan” for additional information regarding the Company’s single contract that falls within the scope of ASC 606. The Company considered the adoption of ASC 606 compared to what would have been recognized by the Company under the prior revenue standard, ASC 605. The adoption of ASC 606 did not have a material impact on the Company’s financial statements as of and for the year ended December 31, 2019.

The Company has determined that the accounting for the Company’s various grant agreements is outside the scope of ASC 606, as the government agencies granting the Company funds are not receiving reciprocal value for their contributions. There are currently no grants outstanding in 2019. Since the accounting for government grants falls outside the scope of ASC 606, the Company has reclassified the grant income earned in 2018 separate and apart from revenue earned from contracts with customers in the Company’s statements of operations to conform to the current year presentation.

In June 2018, the FASB issued ASU 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. This ASU expands the scope of Topic 718, Compensation—Stock Compensation to include share-based payments issued to nonemployees for goods or services. Under the new guidance, the existing employee guidance will apply to nonemployee share based transactions (as long as the transaction is not effectively a form of financing), with the exception of specific guidance related to the attribution of compensation cost. The cost of nonemployee awards will continue to be recorded as if the grantor had paid cash for the goods or services. The new accounting guidance will be effective for the Company on January 1, 2020. The Company has early adopted this new standard on January 1, 2019. The adoption did not have a material impact on the Company’s financial statements.

Recently issued accounting pronouncements

In February 2016, the FASB issued ASU No. 2016‑02, Leases (“ASC 842”), which requires a lessee to recognize assets and liabilities on the balance sheet for operating leases and changes many key definitions, including the definition of a lease. The new standard includes a short‑term lease exception for leases with a term of 12 months or less, as part of which a lessee can make an accounting policy election not to recognize lease assets and lease liabilities. Lessees will continue to differentiate between finance leases (previously referred to as capital leases) and operating leases using classification criteria that are substantially similar to the previous guidance. The new standard will be effective for the Company in fiscal years beginning after December 15, 2020, and early adoption is permitted. The Company anticipates that the adoption of this standard will have an impact on its balance sheet due to the recognition of right-of-use assets and lease liabilities; however, the Company is currently evaluating the impact that the adoption of ASC 842 will have on its financial statements.