Summary of significant accounting policies	6 Months Ended
Jun. 30, 2018
Summary of significant accounting policies
Summary of significant accounting policies	2.Summary of significant accounting policies Basis of presentation The condensed financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted from this report, as is permitted by such rules and regulations. The accompanying condensed financial statements reflect all adjustments consisting of normal, recurring adjustments that are necessary for a fair presentation of the financial position results of operations and cash flows for the interim periods presented. Interim results are not necessarily indicative of results for a full year. Accordingly, these financial statements should be read in conjunction with the financial statements as of and for the year ended December 31, 2017, and notes thereto, included in the Company’s final prospectus for the IPO filed with the SEC pursuant to Rule 424(b)(4) dated June 20, 2018 (the “Prospectus”). 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. Reverse stock split On June 7, 2018, the Company effected a one-for‑27.58621 reverse stock split of the Company’s issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for the Company’s convertible preferred stock. The par value per share and authorized shares of common and convertible preferred stock were not adjusted as a result of the reverse stock split. All common stock and common stock per share amounts within the financial statements and notes thereto have been retroactively adjusted for all periods presented to give effect to this reverse stock split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital. Use of estimates The financial statements are prepared in conformity with GAAP. This process requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates. Significant accounting policies The Company’s significant accounting policies are described in Note 3, “Summary of significant accounting policies,” in the Prospectus. There have been no material changes to the significant accounting policies during the period ended June 30, 2018. Recently issued accounting pronouncements In February 2016, the FASB issued ASU 2016‑02, Leases (“ASU 2016‑02”), 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 beginning after December 15, 2019, and early adoption is permitted. The Company is currently evaluating the potential impact ASU 2016‑02 may have on its financial statements. In May 2014, the FASB issued ASU No. 2014‑09, Revenue from Contracts with Customers (“ASU 2014‑09”), which supersedes nearly all existing revenue recognition guidance. The core principle of ASU 2014‑09 is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration to which an entity expects to be entitled for those goods or services. ASU 2014‑09 defines a five step process to achieve this core principle and, in doing so, more judgment and estimates may be required within the revenue recognition process than are required under existing GAAP. The standard is effective for annual periods beginning after December 15, 2018, using either of the following transition methods: (i) a full retrospective approach reflecting the application of the standard in each prior reporting period with the option to elect certain practical expedients, or (ii) a retrospective approach with the cumulative effect of initially adopting ASU 2014‑09 recognized at the date of adoption (which includes additional footnote disclosures). The Company is evaluating the impact of the pending adoption of ASU 2014‑09 on the financial statements and has not yet determined the method by which the Company will adopt the standard when required.

2.Summary of significant accounting policies

Basis of presentation

The condensed financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted from this report, as is permitted by such rules and regulations. The accompanying condensed financial statements reflect all adjustments consisting of normal, recurring adjustments that are necessary for a fair presentation of the financial position results of operations and cash flows for the interim periods presented. Interim results are not necessarily indicative of results for a full year. Accordingly, these financial statements should be read in conjunction with the financial statements as of and for the year ended December 31, 2017, and notes thereto, included in the Company’s final prospectus for the IPO filed with the SEC pursuant to Rule 424(b)(4) dated June 20, 2018 (the “Prospectus”).

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.

Reverse stock split

On June 7, 2018, the Company effected a one-for‑27.58621 reverse stock split of the Company’s issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for the Company’s convertible preferred stock. The par value per share and authorized shares of common and convertible preferred stock were not adjusted as a result of the reverse stock split. All common stock and common stock per share amounts within the financial statements and notes thereto have been retroactively adjusted for all periods presented to give effect to this reverse stock split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital.

Use of estimates

The financial statements are prepared in conformity with GAAP. This process requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates.

Significant accounting policies

The Company’s significant accounting policies are described in Note 3, “Summary of significant accounting policies,” in the Prospectus. There have been no material changes to the significant accounting policies during the period ended June 30, 2018.

Recently issued accounting pronouncements

In February 2016, the FASB issued ASU 2016‑02, Leases (“ASU 2016‑02”), 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 beginning after December 15, 2019, and early adoption is permitted. The Company is currently evaluating the potential impact ASU 2016‑02 may have on its financial statements.

In May 2014, the FASB issued ASU No. 2014‑09, Revenue from Contracts with Customers (“ASU 2014‑09”), which supersedes nearly all existing revenue recognition guidance. The core principle of ASU 2014‑09 is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration to which an entity expects to be entitled for those goods or services. ASU 2014‑09 defines a five step process to achieve this core principle and, in doing so, more judgment and estimates may be required within the revenue recognition process than are required under existing GAAP. The standard is effective for annual periods beginning after December 15, 2018, using either of the following transition methods: (i) a full retrospective approach reflecting the application of the standard in each prior reporting period with the option to elect certain practical expedients, or (ii) a retrospective approach with the cumulative effect of initially adopting ASU 2014‑09 recognized at the date of adoption (which includes additional footnote disclosures). The Company is evaluating the impact of the pending adoption of ASU 2014‑09 on the financial statements and has not yet determined the method by which the Company will adopt the standard when required.