Summary of significant accounting policies	3 Months Ended
Mar. 31, 2020
Accounting Policies [Abstract]
Summary of significant accounting policies	Summary of significant accounting policies The following is a summary of significant accounting policies followed in the preparation of these condensed consolidated financial statements. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the Company's audited consolidated financial statements and the accompanying notes included in the Company's Annual Report on Form 10-K for the year ended December 31, 2019 (“2019 Form 10-K”). The Company's accounting policies are described in the “Notes to Consolidated Financial Statements” in the Company's 2019 Form 10-K and updated, as necessary, in the Company's Quarterly Reports on Form 10-Q. The December 31, 2019 condensed consolidated balance sheet data presented for comparative purposes were derived from the Company's audited financial statements but do not include all disclosures required by U.S. GAAP. The results of operations for the three months ended March 31, 2020 are not necessarily indicative of the operating results for the full year or for any other subsequent interim period. Basis of presentation The accompanying unaudited condensed consolidated financial statements include those accounts of the Company and a wholly owned subsidiary after elimination of all intercompany accounts and transactions. The Company operates as one segment, which is discovering, researching, developing and commercializing novel cancer immunotherapies. Use of estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, estimates related to clinical trial accruals, estimates related to prepaid and accrued research and development expenses, stock-based compensation expense, and warrants to purchase redeemable securities. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions. Significant accounting policies There were no changes to significant accounting policies during the three months ended March 31, 2020, as compared to the those disclosed in the 2019 Form 10-K. New Accounting Pronouncements The following new accounting pronouncements were adopted by the Company on January 1, 2020: In 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses on certain types of financial instruments, including trade receivables and available-for-sale debt securities. The Company early adopted the standard on January 1, 2020. Based on the composition of the Company's investment portfolio, which includes only money market funds, and the insignificance of the Company's other financial assets, current market conditions, and historical credit loss activity, the adoption of this standard did not have a material impact on the Company's consolidated financial statements and related disclosures. In 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”). The new standard requires public entities to disclose certain new information and modifies some disclosure requirements. The Company adopted the standard on the required effective date of January 1, 2020. This standard did not have a material impact on the Company's disclosures. In 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”). ASU 2018-15 requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance in Accounting Standards Codification 350-40 to determine which implementation costs to defer and recognize as an asset. The Company adopted the standard on the required effective date of January 1, 2020. This standard did not have a material impact on the Company's consolidated financial statements and related disclosures. The following new accounting pronouncements have been issued but are not yet effective: In 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ("ASU 2019-12"). ASU 2019-12 simplifies the accounting for income taxes and will be effective beginning after December 15, 2020. The Company is currently evaluating the impact of ASU 2019-12 in the consolidated financial statements, including accounting policies, processes, and systems. Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s consolidated financial statements upon adoption.

Summary of significant accounting policies

The following is a summary of significant accounting policies followed in the preparation of these condensed consolidated financial statements.

The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the Company's audited consolidated financial statements and the accompanying notes included in the Company's Annual Report on Form 10-K for the year ended December 31, 2019 (“2019 Form 10-K”). The Company's accounting policies are described in the “Notes to Consolidated Financial Statements” in the Company's 2019 Form 10-K and updated, as necessary, in the Company's Quarterly Reports on Form 10-Q. The December 31, 2019 condensed consolidated balance sheet data presented for comparative purposes were derived from the Company's audited financial statements but do not include all disclosures required by U.S. GAAP. The results of operations for the three months ended March 31, 2020 are not necessarily indicative of the operating results for the full year or for any other subsequent interim period.

Basis of presentation

The accompanying unaudited condensed consolidated financial statements include those accounts of the Company and a wholly owned subsidiary after elimination of all intercompany accounts and transactions. The Company operates as one segment, which is discovering, researching, developing and commercializing novel cancer immunotherapies.

Use of estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, estimates related to clinical trial accruals, estimates related to prepaid and accrued research and development expenses, stock-based compensation expense, and warrants to purchase redeemable securities. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.

Significant accounting policies

There were no changes to significant accounting policies during the three months ended March 31, 2020, as compared to the those disclosed in the 2019 Form 10-K.

New Accounting Pronouncements

The following new accounting pronouncements were adopted by the Company on January 1, 2020:

In 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses on certain types of financial instruments, including trade receivables and available-for-sale debt securities. The Company early adopted the standard on January 1, 2020. Based on the composition of the Company's investment portfolio, which includes only money market funds, and the insignificance of the Company's other financial assets, current market conditions, and historical credit loss activity, the adoption of this standard did not have a material impact on the Company's consolidated financial statements and related disclosures.

In 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”). The new standard requires public entities to disclose certain new information and modifies some disclosure requirements. The Company adopted the standard on the required effective date of January 1, 2020. This standard did not have a material impact on the Company's disclosures.

In 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”). ASU 2018-15 requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance in Accounting Standards Codification 350-40 to determine which implementation costs to defer and recognize as an asset. The Company adopted the standard on the required effective date of January 1, 2020. This standard did not have a material impact on the Company's consolidated financial statements and related disclosures.

The following new accounting pronouncements have been issued but are not yet effective:

In 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ("ASU 2019-12"). ASU 2019-12 simplifies the accounting for income taxes and will be effective beginning after December 15, 2020. The Company is currently evaluating the impact of ASU 2019-12 in the consolidated financial statements, including accounting policies, processes, and systems.

Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s consolidated financial statements upon adoption.