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Checkmate Pharmaceuticals (CMPI)

Cover Page

Cover Page - shares6 Months Ended
Jun. 30, 2020Sep. 18, 2020
Document Information [Line Items]
Document Type10-Q
Amendment Flagfalse
Document Period End DateJun. 30,
2020
Document Fiscal Year Focus2020
Document Fiscal Period FocusQ2
Document Quarterly Reporttrue
Document Transition Reportfalse
Entity Interactive Data CurrentYes
Entity Registrant NameCheckmate Pharmaceuticals, Inc.
Entity Central Index Key0001651431
Current Fiscal Year End Date--12-31
Entity Current Reporting StatusNo
Entity Shell Companyfalse
Entity Filer CategoryNon-accelerated Filer
Entity Small Businesstrue
Entity Emerging Growth Companytrue
Entity Ex Transition Periodfalse
Entity Incorporation, State or Country CodeDE
Entity Address, State or ProvinceDE
Entity Address, CountryMA
Title of 12(b) SecurityCommon Stock
Trading SymbolCMPI
Security Exchange NameNASDAQ
Entity Common Stock, Shares Outstanding21,546,591

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in ThousandsJun. 30, 2020Dec. 31, 2019
Current Assets:
Cash and cash equivalents $ 80,289 $ 4,185
Restricted cash20 20
Prepaid expenses and other current assets3,147 921
Total current assets83,456 5,126
Total assets83,456 5,126
Current Liabilities:
Accounts payable3,249 2,234
Accrued expenses3,736 3,100
Series B preferred stock tranche right liability300
Total current liabilities6,985 5,634
Total liabilities6,985 5,634
Commitments and Contingencies (Note 10)
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount194,268 96,928
Stockholders' Deficit:
Common stock, $0.0001 par value; 146,000,000 and 76,000,000 shares authorized as of June 30, 2020 and December 31, 2019, respectively; 1,488,489 shares issued and outstanding as of June 30, 2020 and December 31, 2019;1 1
Additional paid-in capital
Accumulated deficit(117,798)(97,437)
Total stockholders' deficit(117,797)(97,436)
Total liabilities, redeemable convertible preferred stock and stockholders' deficit83,456 5,126
Series A Redeemable Convertible Preferred Stock [Member]
Current Liabilities:
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount33,479 32,482
Series B Redeemable Convertible Preferred Stock [Member]
Current Liabilities:
Series B preferred stock tranche right liability300
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount75,314 $ 64,446
Series C Redeemable Convertible Preferred Stock [Member]
Current Liabilities:
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount $ 85,475

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - USD ($) $ in ThousandsJun. 30, 2020Dec. 31, 2019
Temporary equity number of shares issued108,096,207 51,283,386
Temporary equity number of shares outstanding108,096,207 51,283,386
Temporary equity liquidation preference $ 193,968 $ 96,928
Common stock par value per share $ 0.0001 $ 0.0001
Common stock number of shares authorised146,000,000 76,000,000
Common stock number of shares issued1,488,489 1,488,489
Common stock number of shares outstanding1,488,489 1,488,489
Series A Redeemable Convertible Preferred Stock [Member]
Temporary equity par value per share $ 0.0001 $ 0.0001
Temporary equity number of shares authorised25,000,000 25,000,000
Temporary equity number of shares issued25,000,000 25,000,000
Temporary equity number of shares outstanding25,000,000 25,000,000
Temporary equity liquidation preference $ 33,479 $ 32,482
Series B Redeemable Convertible Preferred Stock [Member]
Temporary equity par value per share $ 0.0001 $ 0.0001
Temporary equity number of shares authorised29,972,284 29,972,284
Temporary equity number of shares issued29,972,284 26,283,386
Temporary equity number of shares outstanding29,972,284 26,283,386
Temporary equity liquidation preference $ 75,014 $ 64,446
Series C Redeemable Convertible Preferred Stock [Member]
Temporary equity par value per share $ 0.0001 $ 0.0001
Temporary equity number of shares authorised62,489,557
Temporary equity number of shares issued53,123,923
Temporary equity number of shares outstanding53,123,923
Temporary equity liquidation preference $ 85,475

Condensed Statements of Operati

Condensed Statements of Operations And Comprehensive Loss - USD ($) $ in Thousands3 Months Ended6 Months Ended
Jun. 30, 2020Jun. 30, 2019Jun. 30, 2020Jun. 30, 2019
Operating expenses:
Research and development $ 6,476 $ 5,849 $ 12,789 $ 12,049
General and administrative1,795 1,107 3,305 2,157
Total operating expenses8,271 6,956 16,094 14,206
Loss from operations(8,271)(6,956)(16,094)(14,206)
Other income (expense), net:
Interest income6 59 28 116
Change in fair value of convertible loan notes(83)(83)
Total other income (expense), net(77)59 (55)116
Net loss and comprehensive loss(8,348)(6,897)(16,149)(14,090)
Net loss(8,348)(6,897)(16,149)(14,090)
Accretion of issuance costs on redeemable convertible preferred stock(429)(33)(456)(51)
Accrued dividends on redeemable convertible preferred stock(2,187)(1,476)(3,957)(2,728)
Net loss attributable to common stockholders $ (10,964) $ (8,406) $ (20,562) $ (16,869)
Weighted-average common shares outstanding—basic and diluted1,488,489 1,429,484 1,488,489 1,413,935
Net loss per share attributable to common stockholders—basic and diluted $ (7.37) $ (5.88) $ (13.81) $ (11.93)

Condensed Statements of Redeema

Condensed Statements of Redeemable Convertible Preferred Stock And Stockholders' Deficit - USD ($) $ in ThousandsTotalPreferred Stock [Member]Common Stock [Member]Additional Paid-in Capital [Member]Accumulated Deficit [Member]Series A Redeemable Convertible Preferred Stock [Member]Series A Redeemable Convertible Preferred Stock [Member]Preferred Stock [Member]Series B Redeemable Convertible Preferred Stock [Member]Series B Redeemable Convertible Preferred Stock [Member]Preferred Stock [Member]Series C Redeemable Convertible Preferred Stock [Member]Series C Redeemable Convertible Preferred Stock [Member]Preferred Stock [Member]
Beginning balance at Dec. 31, 2018 $ 30,482 $ 41,491
Beginning balance, shares at Dec. 31, 201825,000,000 17,522,259
Beginning balance at Dec. 31, 2018 $ (62,801) $ 1 $ (62,802)
Beginning balance, shares at Dec. 31, 20181,394,961
Issuance of series redeemable convertible preferred, shares5,072,232
Issuance of series redeemable convertible preferred $ 10,949
Accretion of issuance costs related to redeemable convertible preferred stock(51)(51)51
Exercise of stock options74 $ 74
Exercise of stock options, shares77,876
Exercise of series B preferred stock tranche right0
Vesting of restricted stock awards, shares10,276
Stock-based compensation expense157 157
Accrued dividends on redeemable convertible preferred stock(2,728)(231)(2,497) $ 992 1,736
Net loss(14,090)(14,090)
Ending balance at Jun. 30, 2019 $ 31,474 $ 54,227
Ending balance, shares at Jun. 30, 201925,000,000 22,594,491
Ending balance at Jun. 30, 2019(79,439) $ 1 (79,440)
Ending balance, shares at Jun. 30, 20191,483,113
Beginning balance at Mar. 31, 2019 $ 30,975 $ 53,250
Beginning balance, shares at Mar. 31, 201925,000,000 22,594,491
Beginning balance at Mar. 31, 2019(71,185) $ 1 (71,186)
Beginning balance, shares at Mar. 31, 20191,400,099
Issuance of series redeemable convertible preferred $ 33
Conversion of convertible loan notes into redeemable preferred stock(33)
Accretion of issuance costs related to redeemable convertible preferred stock(33)(33)
Exercise of stock options74 74
Exercise of stock options, shares77,876
Vesting of restricted stock awards, shares5,138
Stock-based compensation expense78 78
Accrued dividends on redeemable convertible preferred stock(1,476)(152)(1,324) $ 499 977
Net loss(6,897)(6,897)
Ending balance at Jun. 30, 2019 $ 31,474 $ 54,227
Ending balance, shares at Jun. 30, 201925,000,000 22,594,491
Ending balance at Jun. 30, 2019(79,439) $ 1 (79,440)
Ending balance, shares at Jun. 30, 20191,483,113
Beginning balance at Dec. 31, 2019 $ 96,928 $ 32,482 $ 32,482 $ 64,446 $ 64,446
Beginning balance, shares at Dec. 31, 201951,283,386 25,000,000 25,000,000 26,283,386 26,283,386
Beginning balance at Dec. 31, 2019 $ (97,436) $ 1 (97,437)
Beginning balance, shares at Dec. 31, 20191,488,489
Issuance of series redeemable convertible preferred, shares3,688,898 46,828,167
Issuance of series redeemable convertible preferred $ 7,973 $ 74,571
Conversion of convertible loan notes into redeemable preferred stock $ 10,083
Conversion of convertible loan notes into redeemable preferred stock, shares6,295,756
Accretion of issuance costs related to redeemable convertible preferred stock $ (456)(456)27 $ 429
Exercise of stock options, shares0
Exercise of series B preferred stock tranche right $ 300 300
Stock-based compensation expense201 201
Accrued dividends on redeemable convertible preferred stock(3,957)(201)(3,756) $ 997 2,568 392
Net loss(16,149)(16,149)
Ending balance at Jun. 30, 2020 $ 194,268 $ 33,479 $ 33,479 $ 75,314 $ 75,314 $ 85,475 $ 85,475
Ending balance, shares at Jun. 30, 2020108,096,207 53,123,923 25,000,000 25,000,000 29,972,284 29,972,284 53,123,923 53,123,923
Ending balance at Jun. 30, 2020 $ (117,797) $ 1 (117,798)
Ending balance, shares at Jun. 30, 20201,488,489
Beginning balance at Mar. 31, 2020 $ 32,980 $ 74,018
Beginning balance, shares at Mar. 31, 202025,000,000 29,972,284
Beginning balance at Mar. 31, 2020(106,933) $ 1 (106,934)
Beginning balance, shares at Mar. 31, 20201,488,489
Issuance of series redeemable convertible preferred, shares46,828,167
Issuance of series redeemable convertible preferred $ 74,571
Conversion of convertible loan notes into redeemable preferred stock $ 10,083
Conversion of convertible loan notes into redeemable preferred stock, shares6,295,756
Accretion of issuance costs related to redeemable convertible preferred stock(429)(429) $ 429
Stock-based compensation expense100 100
Accrued dividends on redeemable convertible preferred stock(2,187) $ (100)(2,087) $ 499 $ 1,296 392
Net loss(8,348)(8,348)
Ending balance at Jun. 30, 2020 $ 194,268 $ 33,479 $ 33,479 $ 75,314 $ 75,314 $ 85,475 $ 85,475
Ending balance, shares at Jun. 30, 2020108,096,207 53,123,923 25,000,000 25,000,000 29,972,284 29,972,284 53,123,923 53,123,923
Ending balance at Jun. 30, 2020 $ (117,797) $ 1 $ (117,798)
Ending balance, shares at Jun. 30, 20201,488,489

Condensed Statements of Redee_2

Condensed Statements of Redeemable Convertible Preferred Stock And Stockholders' Deficit (Parenthetical) $ in Thousands6 Months Ended
Jun. 30, 2020USD ($)$ / sharesJun. 30, 2019USD ($)$ / shares
Cash paid for redeemable convertible preferred stock issuance $ 398 $ 0
Series B Redeemable Convertible Preferred Stock [Member]
Shares Issued, Price Per Share | $ / shares $ 2.1687 $ 2.1687
Cash paid for redeemable convertible preferred stock issuance $ 27 $ 51
Series C Redeemable Convertible Preferred Stock [Member]
Shares Issued, Price Per Share | $ / shares $ 1.6016
Cash paid for redeemable convertible preferred stock issuance $ 429

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands6 Months Ended
Jun. 30, 2020Jun. 30, 2019
Cash flows from operating activities
Net loss $ (16,149) $ (14,090)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock based compensation201 157
Change in fair value of notes payable83 0
Change in operating assets and liabilities:
Prepaid expenses and other current assets(610)(207)
Accounts payable(31)(192)
Accrued expenses464 (373)
Net cash used in operating activities(16,042)(14,705)
Cash flows from financing activities
Cash received from stock option exercise0 74
Cash paid for initial public offering costs(398)0
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs82,544 10,949
Proceeds from issuance of convertible loan notes10,000 0
Net cash provided by financing activities92,146 11,023
Net increase (decrease) in cash, cash equivalents and restricted cash76,104 (3,682)
Cash, cash equivalents and restricted cash at beginning of period4,205 12,079
Cash, cash equivalents and restricted cash at end of period80,309 8,397
Supplemental disclosure of non-cash financing activities:
Accretion of issuance costs to redeemable convertible preferred stock456 51
Exercise of series B preferred stock tranche right300 0
Accrued dividends on redeemable convertible preferred stock3,957 2,728
Deferred offering costs included in prepaid expenses and other current assets and accounts payable or accrued expenses1,217 0
Series C Redeemable Convertible Preferred Stock [Member]
Cash flows from financing activities
Cash paid for initial public offering costs(429)
Supplemental disclosure of non-cash financing activities:
Conversion of convertible loan notes into series C preferred stock $ 10,083 $ 0

Nature of Business And Basics o

Nature of Business And Basics of Presentation6 Months Ended
Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business And Basics of Presentation1 – N ATURE OF USINESS AND ASIS OF RESENTATION Nature of Business Checkmate Pharmaceuticals, Inc., or Checkmate or the Company, headquartered non-clinical Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP, and include the accounts of the Company. Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification, or ASC, and Accounting Standards Update, or ASU, of the Financial Accounting Standards Board, or FASB. The Company’s significant accounting policies are disclosed in the audited financial statements for the year ended December 31, 2019, included in the Company’s registration statement on Form S-1 No. 333-239932) Initial Public Offering On August 11 closed at which time August 11, 2020 all convertible preferred stock converted into shares of common stock. Th e unaudited condensed financial statements, including share and per share amounts, do not give effect to the IPO or the related conversion of securities into shares of common stock. On September 3, 2020 the underwriters of the IPO exercised a portion of their overallotment option by purchasing an additional 109,861 shares from the Company at the IPO price, resulting in an additional $1.5 million in net proceeds after deducting the underwriting discounts and commissions. On July 31, 2020, the Company effected a one-for-7.4771 was unaudited Risks and Uncertainties The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, the outcome of clinical trials, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations, ability to secure additional capital to fund operations, and risks associated with the COVID-19 its As of May 13, 2020, the issuance date of the Company’ s audited financial statements for the year ended December 31, 2019, the Company concluded that there was substantial doubt about its ability to continue as a going concern for one year after the date that those financial statements were issued. Subsequent to the issuance of those financial statements, the Company received net and unaudited condensed financial statements, the Company expects its cash and cash equivalents of $80.3 million as of June 30, 2020, together with the net unaudited condensed financial statements. The Company may seek additional funding through private or public equity financings, debt financings, collaborations, strategic alliances and marketing, distribution or licensing agreements. If the Company is unable to obtain additional funding, the Company will be forced to delay, reduce or eliminate some or all of its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects, or the Company may be unable to continue operations. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all. Unaudited interim financial information The accompanying interim unaudited condensed financial statements and related disclosures are unaudited and have been prepared in accordance with GAAP for interim financial information and the instructions to Form 10-Q S-X.

Summary of Significant Accounti

Summary of Significant Accounting Policies6 Months Ended
Jun. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies2 – S UMMARY OF IGNIFICANT CCOUNTING OLICIES The Company’s significant accounting policies are described in Note 3, Summary of Significant Accounting Policies December 31, 2019 in the Registration Statement. There six-month Deferred offering costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity additional paid-in capital. Fair Value Option As permitted under ASC 825, Financial Instruments, or ASC 825, the Company has elected the fair value option to account for its convertible loan notes. In accordance with ASC 825, the Company records these convertible loan notes at fair value with changes in fair value recorded as a component of other income (expense), net in the condensed statements non-contingent Recently adopted accounting pronouncements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes 2019-12. 2019-12 2019-12 In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 2018-18 In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement. ASU No. 2018-13 ASU No. 2018-13 2018-13 In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815) I. Accounting for Certain Financial Instruments with Down Round Features II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception, or ASU 2017-11 . ASU 2017-11 2017-11 2017-11

Fair Value Measurement

Fair Value Measurement6 Months Ended
Jun. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurement3 – F AIR ALUE EASUREMENT The following tables set forth the fair value of the Company’s financial assets and liabilities by level within the fair value hierarchy that are measured at fair value on a recurring basis: June 30, 2020 Level 1 Level 2 Level 3 Total (in thousands) Assets: Money market funds $ 80,045 $ — $ — $ 80,045 Total assets $ 80,045 $ — $ — $ 80,045 December 31, 2019 Level 1 Level 2 Level 3 Total (in thousands) Assets: Money market funds $ 4,003 $ — $ — $ 4,003 Total assets $ 4,003 $ — $ — $ 4,003 Liabilities: Series B preferred stock tranche right liability $ — $ — $ 300 $ 300 Total liabilities $ — $ — $ 300 $ 300 V ALUATION OF ERIES REFERRED TOCK RANCHE IGHT IABILITY The series B preferred stock tranche right liability at December 31, 2019 is composed of the fair value of rights to purchase series B redeemable convertible preferred stock, or Series B. The fair value of the series B preferred stock tranche right liability was determined based on significant inputs not observable in the market, which represent a Level 3 measurement within the fair value hierarchy. The fair value of the preferred stock tranche right liability was determined using a binomial model, which considered as inputs the value of the Series B, the expected return of the underlying Series B during the period between the valuation date and the expected event date, the probability and timing of achieving the specified milestones as of each valuation date and a discount rate. The most significant assumption in the binomial model impacting the fair value of the series B preferred stock tranche right liability is the fair value of the Company’s Series B as of each measurement date. The Company determines the fair value per share of the underlying Series B by taking into consideration the most recent sales of its Series B, results obtained from third-party valuations and additional factors the Company deems relevant. At December 31, 2019, the fair value of each share of Series B was $2.20 per share. The series B preferred stock tranche right was exercised on January 14, 2020. The change in fair value of the series B preferred stock tranche right liability from December 31, 2019 to January 14, 2020 was not material. The following table provides a roll-forward of the aggregate fair value of the Company’s series B preferred stock tranche right liability, for which fair value is determined using Level 3 inputs: Series B Preferred (in thousands) Balance as of December 31, 2019 $ 300 Exercise of series B preferred stock tranche right (300 ) Balance as of June 30, 2020 $ — VALUATION OF CONVERTIBLE LOAN NOTES The Company elected the fair value option to account for its convertible loan notes issued during April 2020. The fair value of the convertible loan notes was determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The fair value of the initial closing of the Company’s convertible loan notes in April 2020 was determined to be equal to the proceeds of $10.0 million on issuance. The fair value of the convertible loan at the time of conversion into the Series C preferred stock in June 2020 was determined to be equal to $1.6016 per share, the value of the Company’s Series C preferred stock into which the convertible loan notes were converted . The change in fair value of the convertible notes prior to close of the Series C preferred stock financing of $0.1 million primarily related to the accrued interest earned on the convertible loan notes prior to such financing . The following table presents a roll-forward of the aggregate fair values of the Company’s convertible loan notes (Note 5) for which fair value is determined by Level 3 inputs: Convertible Loan (in thousands) Balance as of December 31, 2019 Initial fair value $ 10,000 Change in fair value plus accrued interest 83 Settlement of convertible loan note s (10,083 ) Balance as of June 30, 2020 $ —

Accrued Expenses

Accrued Expenses6 Months Ended
Jun. 30, 2020
Payables and Accruals [Abstract]
Accrued Expenses4 – A CCRUED XPENSES Accrued expenses consist of the following: June 30, December 31, 2020 2019 (in thousands) Payroll and employee related expenses $ 837 $ 1,051 External research and development 2,572 1,969 Other accrued expenses 327 80 Total accrued expenses $ 3,736 $ 3,100

Convertible Loan Notes

Convertible Loan Notes6 Months Ended
Jun. 30, 2020
Debt Disclosure [Abstract]
Convertible Loan Notes5 – C ONVERTIBLE OAN OTES On April 21, 2020, the Company entered into a note purchase agreement pursuant to which the Company issued unsecured convertible loan notes to investors for a total of $10.0 million in principal. The Company will pay simple interest on the outstanding principal amount to the extent not converted at the rate of 8% per annum. No repayment of principal or interest was due until maturity, which occurs 12 months after issuance of the convertible loan notes. Under the agreement, the convertible loan notes outstanding principal and unpaid accrued interest automatically convert upon a Qualified Financing. If the Qualified Financing is consummated within (i) three months after the date of the agreement, the conversion price shall be equal to 90% of the per share price paid by the investors; (ii) if consummated more than three months after the date of the agreement, but within six months, the conversion price shall be equal to 80% of the per share price paid by the investors; and (iii) is consummated more than six months after the date of the agreement, the conversion price shall be equal to 70% of the price per share paid by the investors. On June 2, 2020, upon the series C preferred stock financing (Note 6), the outstanding principal and unpaid accrued interest of the convertible notes of $10.1 million converted into 6,295,756 shares of series C preferred stock. Upon execution of the series C preferred stock, the noteholder investors waived their right to the 90% conversion price and converted the notes at 100% of the per share price paid by the investors in the Qualified Financing. The Company elected the fair value option to account for the convertible loan notes. The Company recorded the convertible loan notes at fair value and subsequently remeasured them to fair value upon settlement of the convertible loan notes. Changes in fair value were recognized as a component of other income (expense), net in the condensed statements of operations and comprehensive loss. The Company recognized a loss in the condensed statements of operations and comprehensive loss of $0.1 million as change in fair value of the convertible notes during the three and six months ended June 30, 2020.

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock6 Months Ended
Jun. 30, 2020
Temporary Equity Disclosure [Abstract]
Redeemable Convertible Preferred Stock6 – R EDEEMABLE ONVERTIBLE REFERRED TOCK As of each balance sheet date, the Preferred Stock consisted of the following: June 30, 2020 Issued and Carrying Liquidation Common (dollars in thousands) Series A 25,000,000 $ 33,479 $ 33,479 3,343,542 Series B 29,972,284 75,314 75,014 4,499,824 Series C 53,123,923 85,475 85,475 7,104,883 108,096,207 $ 194,268 $ 193,968 14,948,249 December 31, 2019 Issued and Carrying Liquidation Common (dollars in thousands) Series A 25,000,000 $ 32,482 $ 32,482 3,343,542 Series B 26,283,386 64,446 64,446 3,946,001 51,283,386 $ 96,928 $ 96,928 7,289,543 Preferred stock is classified outside of stockholders’ deficit because the shares contain redemption features that are not solely within the control of the Company. Series C Preferred Stock Financing In June 2020, the Company entered into the Series C Preferred Stock Purchase Agreement, or the Series C Agreement, pursuant to which the Company was authorized to issue 62,489,557 shares of Series C convertible preferred stock (Series C), at a price of $1.6016 per share. As part of the closing, the Company issued 46,828,167 shares of Series C at $1.6016 per share for consideration of $75.0 million and an additional 6,295,756 shares of Series C in satisfaction of the conversion of $10.0 million convertible loan notes and $0.1 million of accrued interest. The aggregate purchase price of the Series C was $85.1 million and the Company incurred issuance costs of $0.4 million, which was recorded as a reduction to the Series C carrying value. Series B Preferred Stock Financing In January 2020, the Company issued 3,688,898 of Series B at a price of $2.16867 per share, resulting in net proceeds received of $8.0 million. The rights and preferences of the Series B issued in January 2020 are identical to Series B issued in prior periods. As a result of the issuance, the fair value of the associated outstanding series B tranche right liability of $0.3 million was reclassified to Series B. In connection with the Series C financing, the conversion price of the Series B was decreased from $16.21536 to $14.4451 such that the rate at which shares of Series B may be converted into shares of common stock was adjusted from 1:1 to 0.15013:1. Dividends Preferred stock accrues dividends on a cumulative basis at $0.08 per share per annum for Series A, $0.17349 per share per annum for Series B and $0.128128 per share per annum for Series C, to be calculated daily and is payable when and if declared by the Company’s board of directors . No dividends may be paid to common stockholders until all dividends to preferred stockholders are paid in full, except stock dividends paid to common stockholders. Cumulative dividends were as follows: June 30, December 31, 2020 2019 (in thousands) Series A $ 8,479 $ 7,482 Series B $ 10,014 $ 7,446 Series C $ 392 $ — Through June 30, 2020, no dividends have been declared or paid by the Company.

Common Stock

Common Stock6 Months Ended
Jun. 30, 2020
Equity [Abstract]
Common Stock7 – C OMMON TOCK The voting, dividend and liquidation rights of the common stockholders are subject to and qualified by the rights, powers and preferences of the preferred stock. The holders of the common stock are entitled to one vote for each share of common stock held at all meetings of stockholders. Common stockholders are entitled to receive dividends declared out of funds legally available, subject to the payment in full of all preferential dividends to which the holders of preferred stock are entitled. In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company, after the payment or provision for payment of all debts and liabilities of the Company and all preferential amounts to which the holders of preferred stock are entitled, if any, the common stockholders and preferred stockholders (on an as-converted The Company’s common stock available for future issuance as of June 30, 2020 is summarized as follows: Common stock authorized 146,000,000 Common stock authorized, issued and outstanding 1,488,489 Common stock authorized and reserved for future issuance: Common stock reserved for the conversion of Series A 3,343,542 Common stock reserved for the conversion of Series B 4,499,824 Common stock reserved for the conversion of Series C 7,104,883 Common stock reserved for future exercises of stock option awards 1,073,044 Common stock reserved for future share-based 729,575 Total common stock authorized and reserved for future issuance 18,239,357 Unreserved common stock available for future issuance 127,760,643

Stock based compensation

Stock based compensation6 Months Ended
Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
Stock based compensation8 – S TOCK ASED OMPENSATION Stock Options In August 2015, the Company’s board of directors approved the Checkmate Pharmaceuticals, Inc. 2015 Stock Option and Grant Plan, or 2015 Plan, to encourage and enable the officers, employees, directors, consultants 2015 d non-statutory board of directors shares of 2015 was were The Company estimates the fair value of stock option awards on the grant date using the Black-Scholes option valuation model with the following weighted-average assumptions: Three and Six Months Ended June 30, 2020 2019 Risk-free interest rate N/A 1.30 % Expected term (in years) N/A 5.75 Expected volatility N/A 70.0 % Dividend yield N/A — There were no stock options granted during the three and six months ended June 30, 2020. The per share weighted average grant date fair value of stock options granted during the three and six months ended June 30, 2019 was $1.61. As of June 30, 2020, total unrecognized compensation expense related to stock options totaled $0.95 million, which is expected to be recognized over a weighted average period of 2.6 years. The following table summarizes the activity under the Company’s stock option plan during the six months ended June 30, 2020: Number of Options Weighted- Average Exercise Price Weighted- Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2019 1,073,044 $ 2.45 8.7 $ 906 Granted — $ — Forfeited — $ — Exercised — $ — Outstanding at June 30, 2020 1,073,044 $ 2.45 8.2 $ 906 Vested and expected to vest at June 30, 2020 1,073,044 $ 2.45 8.2 $ 906 Exercisable at June 30, 2020 426,980 $ 2.23 7.6 $ 468 The aggregate intrinsic value of options is calculated as the difference between the exercise price of the options and the fair value of the Company’s common stock for those options that had exercise prices lower than the fair value of the Company’s common stock. There were no options exercised during the six months ended June 30, 2020. Restricted Stock The Company did not grant restricted stock during the six months ended June 30, 2020. All previously granted restricted stock was fully vested as of December 31, 2019. Stock-based Compensation Expense Total stock-based compensation expense was classified in the accompanying condensed statements of operations and comprehensive loss as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 ( in thousands) (in thousands) Research and development $ 39 $ 25 $ 78 $ 49 General and administrative 61 53 123 108 Total stock-based compensation expense $ 100 $ 78 $ 201 $ 157

Income taxes

Income taxes6 Months Ended
Jun. 30, 2020
Income Tax Disclosure [Abstract]
Income taxes9 – I NCOME AXES The Company incurred federal and state net operating losses and recorded a full valuation allowance against net deferred assets for all periods presented. Accordingly, the Company has not recorded a provision for federal or state income taxes. The Coronavirus Aid, Relief, and Economic Security Act, or CARES Act, signed into United States law on March 27, 2020 modifies certain provisions of the Tax Cuts and Jobs Act, or TCJA with respect to net operating losses. Under the CARES Act, the limitation on the deduction of net operating losses to 80% of annual taxable income is removed for taxable years beginning before January 1, 2021. The CARES Act did not have a material impact on the unaudited condensed financial statements.

Net Loss Per Share

Net Loss Per Share6 Months Ended
Jun. 30, 2020
Earnings Per Share [Abstract]
Net Loss Per Share10 – N ET OSS ER HARE Net Loss Per Share Attributable To Common Stockholders Because the Company reports a net loss attributable to common stockholders, basic and diluted net loss per share attributable to common stockholders are the same for both years presented. All preferred stock, unvested restricted stock, and stock options have been excluded from the computation of diluted weighted-average shares outstanding because such securities would have an antidilutive impact. Basic and diluted net loss per share attributable to common stockholders was calculated as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 (in thousands, except share (in thousands, except share Numerator Net loss $ (8,348 ) $ (6,897 ) $ (16,149 ) $ (14,090 ) Accretion of issuance costs on redeemable convertible preferred stock (429 ) (33 ) (456 ) (51 ) Accrued dividends on redeemable convertible preferred stock (2,187 ) (1,476 ) (3,957 ) (2,728 ) Net Loss attributable to common stockholders $ (10,964 ) $ (8,406 ) $ (20,562 ) $ (16,869 ) Denominator: Weighted-average common shares outstanding—basic and diluted 1,488,489 1,429,484 1,488,489 1,413,935 Net loss per share attributable to common stockholders—basic and diluted $ (7.37 ) $ (5.88 ) $ (13.81 ) $ (11.93 ) The following common stock equivalents outstanding at June 30, 2020 and 2019 have been excluded from the calculation of diluted net loss per share because their inclusion would have been antidilutive: June 30, 2020 2019 Options to purchase common stock 1,073,044 812,539 Unvested restricted common stock — 5,376 Redeemable convertible preferred stock 14,948,249 6,365,368

Commitments And Contingencies

Commitments And Contingencies6 Months Ended
Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies11 – C OMMITMENTS AND ONTINGENCIES Operating Lease The Company has a month-to-month months ended June 30, 2020 and 2019 was $0.1 million and $0.1 million, respectively. Rent expense for the , Clinical Trial Collaboration and Supply Agreement On August 22, 2018, the Company entered into the Clinical Trial Collaboration and Supply Agreement, or CTCSA Agreement, with an affiliate of Merck KgaA, or Merck, and Pfizer Inc., or Pfizer, (Merck and Pfizer together are referred to herein as the “Alliance”). Pursuant to the CTCSA, the Company, and the Alliance will each provide compound drug product that will be dosed concurrently or in combination in a clinical trial sponsored by Pfizer. This agreement was amended on March 4, 2019. In addition to providing a compound drug product to be used in the clinical trial, the Company will reimburse Pfizer for each patient dosed in the study using the Company’s compound at a specified rate outlined in the CTCSA Agreement. In no event will the amount of costs due by the Company to Pfizer exceed $4.0 million over the term of the CTCSA Agreement. The costs of services performed and material used in connection with the research and development activities of the CTCSA Agreement, including reimbursements due to Pfizer, are included in research and development costs and expensed as incurred. The Company incurred $0.5 million and $0.1 million of expense during the three and six months ended June 30, 2020, respectively, and no expense relating to the Pfizer reimbursement during the three and six months ended June 30, 2019. License Agreement In June 2015, the Company entered into an exclusive license agreement with Cytos Biotechnology LTD (now Kuros Biosciences AG or Kuros) as amended in August 2017 and as further amended in January 2018 (the Kuros License Agreement). Pursuant to the Kuros License Agreement, in return for payments made, the Company was granted an exclusive, royalty-bearing, sublicensable, worldwide license, under all of Kuros’s intellectual property rights, including any intellectual property rights arising during the term of the agreement, to commercially develop, manufacture, use, distribute, and sell certain therapeutic products, including CMP-001, CMP-001 CMP-001. As of June 30, 20 20 Other Contingencies During the ordinary course of its operations, the Company may become a party to contractual disputes, litigation, and potential claims. The Company does not believe that the resolution of any of these matters, if any, will have a material adverse effect on its financial position or results of operations.

Subsequent Events

Subsequent Events6 Months Ended
Jun. 30, 2020
Subsequent Events [Abstract]
Subsequent Events12 – S UBSEQUENT VENTS In August 2020 , Company’s board of directors and stockholders adopted and approved Plan, or the 2020 Plan. non-employee directors consultants 2020 % Plan In August 2020 , the b d the Checkmate Pharmaceuticals, Inc. 2020 Employee Stock Purchase Plan, or 2020 ESPP . The 2020 ESPP was created to provide eligible employees of the Company and other qualified participants to purchase the Company’s common stock at 85% of the fair market value of the common stock on the offering date or the exercise date, whichever is for up to 15% of such employee’s compensation for each pay period. The Company reserved 267,119 shares of common stock for the 2020 ESPP. The 2020 ESPP provides for an annual increase in the number of shares of common stock to be reserved for future issuance under the 2020 ESPP .

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)6 Months Ended
Jun. 30, 2020
Accounting Policies [Abstract]
Nature of BusinessNature of Business Checkmate Pharmaceuticals, Inc., or Checkmate or the Company, headquartered non-clinical
Basis of PresentationBasis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP, and include the accounts of the Company. Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification, or ASC, and Accounting Standards Update, or ASU, of the Financial Accounting Standards Board, or FASB. The Company’s significant accounting policies are disclosed in the audited financial statements for the year ended December 31, 2019, included in the Company’s registration statement on Form S-1 No. 333-239932)
Initial Public OfferingInitial Public Offering On August 11 closed at which time August 11, 2020 all convertible preferred stock converted into shares of common stock. Th e unaudited condensed financial statements, including share and per share amounts, do not give effect to the IPO or the related conversion of securities into shares of common stock. On September 3, 2020 the underwriters of the IPO exercised a portion of their overallotment option by purchasing an additional 109,861 shares from the Company at the IPO price, resulting in an additional $1.5 million in net proceeds after deducting the underwriting discounts and commissions. On July 31, 2020, the Company effected a one-for-7.4771 was unaudited
Risks and UncertaintiesRisks and Uncertainties The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, the outcome of clinical trials, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations, ability to secure additional capital to fund operations, and risks associated with the COVID-19 its As of May 13, 2020, the issuance date of the Company’ s audited financial statements for the year ended December 31, 2019, the Company concluded that there was substantial doubt about its ability to continue as a going concern for one year after the date that those financial statements were issued. Subsequent to the issuance of those financial statements, the Company received net and unaudited condensed financial statements, the Company expects its cash and cash equivalents of $80.3 million as of June 30, 2020, together with the net unaudited condensed financial statements. The Company may seek additional funding through private or public equity financings, debt financings, collaborations, strategic alliances and marketing, distribution or licensing agreements. If the Company is unable to obtain additional funding, the Company will be forced to delay, reduce or eliminate some or all of its research and development programs, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects, or the Company may be unable to continue operations. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all.
Unaudited interim financial informationUnaudited interim financial information The accompanying interim unaudited condensed financial statements and related disclosures are unaudited and have been prepared in accordance with GAAP for interim financial information and the instructions to Form 10-Q S-X.
Deferred offering costsDeferred offering costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity additional paid-in capital.
Fair Value OptionFair Value Option As permitted under ASC 825, Financial Instruments, or ASC 825, the Company has elected the fair value option to account for its convertible loan notes. In accordance with ASC 825, the Company records these convertible loan notes at fair value with changes in fair value recorded as a component of other income (expense), net in the condensed statements non-contingent
Recently adopted accounting pronouncementsRecently adopted accounting pronouncements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes 2019-12. 2019-12 2019-12 In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 2018-18 In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement. ASU No. 2018-13 ASU No. 2018-13 2018-13 In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815) I. Accounting for Certain Financial Instruments with Down Round Features II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception, or ASU 2017-11 . ASU 2017-11 2017-11 2017-11

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)6 Months Ended
Jun. 30, 2020
Fair Value Disclosures [Abstract]
Schedule of Fair Value Assets And Liabilities Measured On Recurring Basis June 30, 2020 Level 1 Level 2 Level 3 Total (in thousands) Assets: Money market funds $ 80,045 $ — $ — $ 80,045 Total assets $ 80,045 $ — $ — $ 80,045 December 31, 2019 Level 1 Level 2 Level 3 Total (in thousands) Assets: Money market funds $ 4,003 $ — $ — $ 4,003 Total assets $ 4,003 $ — $ — $ 4,003 Liabilities: Series B preferred stock tranche right liability $ — $ — $ 300 $ 300 Total liabilities $ — $ — $ 300 $ 300
Schedule of Aggregate Fair Value of The Company's Series B Preferred Stock Tranche Right LiabilityThe following table provides a roll-forward of the aggregate fair value of the Company’s series B preferred stock tranche right liability, for which fair value is determined using Level 3 inputs: Series B Preferred (in thousands) Balance as of December 31, 2019 $ 300 Exercise of series B preferred stock tranche right (300 ) Balance as of June 30, 2020 $ —
Schedule of Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input ReconciliationThe following table presents a roll-forward of the aggregate fair values of the Company’s convertible loan notes (Note 5) for which fair value is determined by Level 3 inputs: Convertible Loan (in thousands) Balance as of December 31, 2019 Initial fair value $ 10,000 Change in fair value plus accrued interest 83 Settlement of convertible loan note s (10,083 ) Balance as of June 30, 2020 $ —

Accrued Expenses (Tables)

Accrued Expenses (Tables)6 Months Ended
Jun. 30, 2020
Payables and Accruals [Abstract]
Accrued ExpensesAccrued expenses consist of the following: June 30, December 31, 2020 2019 (in thousands) Payroll and employee related expenses $ 837 $ 1,051 External research and development 2,572 1,969 Other accrued expenses 327 80 Total accrued expenses $ 3,736 $ 3,100

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock (Tables)6 Months Ended
Jun. 30, 2020
Temporary Equity Disclosure [Abstract]
Schedule of Redeemable Convertible Preferred StockAs of each balance sheet date, the Preferred Stock consisted of the following: June 30, 2020 Issued and Carrying Liquidation Common (dollars in thousands) Series A 25,000,000 $ 33,479 $ 33,479 3,343,542 Series B 29,972,284 75,314 75,014 4,499,824 Series C 53,123,923 85,475 85,475 7,104,883 108,096,207 $ 194,268 $ 193,968 14,948,249 December 31, 2019 Issued and Carrying Liquidation Common (dollars in thousands) Series A 25,000,000 $ 32,482 $ 32,482 3,343,542 Series B 26,283,386 64,446 64,446 3,946,001 51,283,386 $ 96,928 $ 96,928 7,289,543
Schedule of Cumulative DividendsCumulative dividends were as follows: June 30, December 31, 2020 2019 (in thousands) Series A $ 8,479 $ 7,482 Series B $ 10,014 $ 7,446 Series C $ 392 $ —

Common Stock (Tables)

Common Stock (Tables)6 Months Ended
Jun. 30, 2020
Equity [Abstract]
Summary of Common Stock Available for Future IssuanceThe Company’s common stock available for future issuance as of June 30, 2020 is summarized as follows: Common stock authorized 146,000,000 Common stock authorized, issued and outstanding 1,488,489 Common stock authorized and reserved for future issuance: Common stock reserved for the conversion of Series A 3,343,542 Common stock reserved for the conversion of Series B 4,499,824 Common stock reserved for the conversion of Series C 7,104,883 Common stock reserved for future exercises of stock option awards 1,073,044 Common stock reserved for future share-based 729,575 Total common stock authorized and reserved for future issuance 18,239,357 Unreserved common stock available for future issuance 127,760,643

Stock based compensation - (Ta

Stock based compensation - (Tables)6 Months Ended
Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
Schedule of fair value of stock option awards on the grant date using the black-scholes option valuation modelThe Company estimates the fair value of stock option awards on the grant date using the Black-Scholes option valuation model with the following weighted-average assumptions: Three and Six Months Ended June 30, 2020 2019 Risk-free interest rate N/A 1.30 % Expected term (in years) N/A 5.75 Expected volatility N/A 70.0 % Dividend yield N/A —
Summary of activity under the company's stock option planThe following table summarizes the activity under the Company’s stock option plan during the six months ended June 30, 2020: Number of Options Weighted- Average Exercise Price Weighted- Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2019 1,073,044 $ 2.45 8.7 $ 906 Granted — $ — Forfeited — $ — Exercised — $ — Outstanding at June 30, 2020 1,073,044 $ 2.45 8.2 $ 906 Vested and expected to vest at June 30, 2020 1,073,044 $ 2.45 8.2 $ 906 Exercisable at June 30, 2020 426,980 $ 2.23 7.6 $ 468
Summary of total stock-based compensation expenseTotal stock-based compensation expense was classified in the accompanying condensed statements of operations and comprehensive loss as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 ( in thousands) (in thousands) Research and development $ 39 $ 25 $ 78 $ 49 General and administrative 61 53 123 108 Total stock-based compensation expense $ 100 $ 78 $ 201 $ 157

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)6 Months Ended
Jun. 30, 2020
Earnings Per Share [Abstract]
Summary of Basic And Diluted Net Loss Per Share Attributable To Common StockholdersBasic and diluted net loss per share attributable to common stockholders was calculated as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 (in thousands, except share (in thousands, except share Numerator Net loss $ (8,348 ) $ (6,897 ) $ (16,149 ) $ (14,090 ) Accretion of issuance costs on redeemable convertible preferred stock (429 ) (33 ) (456 ) (51 ) Accrued dividends on redeemable convertible preferred stock (2,187 ) (1,476 ) (3,957 ) (2,728 ) Net Loss attributable to common stockholders $ (10,964 ) $ (8,406 ) $ (20,562 ) $ (16,869 ) Denominator: Weighted-average common shares outstanding—basic and diluted 1,488,489 1,429,484 1,488,489 1,413,935 Net loss per share attributable to common stockholders—basic and diluted $ (7.37 ) $ (5.88 ) $ (13.81 ) $ (11.93 )
Summary of Potentially Dilutive Shares Excluded From The Calculation of Diluted Net LossThe following common stock equivalents outstanding at June 30, 2020 and 2019 have been excluded from the calculation of diluted net loss per share because their inclusion would have been antidilutive: June 30, 2020 2019 Options to purchase common stock 1,073,046 812,539 Unvested restricted common stock — 5,376 Redeemable convertible preferred stock 14,948,249 6,365,368

Nature of Business And Basics_2

Nature of Business And Basics of Presentation - Additional Information (Detail) $ / shares in Units, $ in ThousandsSep. 03, 2020USD ($)sharesAug. 31, 2020USD ($)Aug. 11, 2020USD ($)$ / sharessharesJul. 31, 2020Jun. 30, 2020USD ($)$ / sharesJun. 30, 2019USD ($)Dec. 31, 2019USD ($)
Subsidiary, Sale of Stock [Line Items]
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs $ 82,544 $ 10,949
Cash and cash equivalents $ 80,289 $ 4,185
Series C Redeemable Convertible Preferred Stock [Member]
Subsidiary, Sale of Stock [Line Items]
Shares Issued, Price Per Share | $ / shares $ 1.6016
Proceeds from initial public offering gross $ 75,000
Common Stock [Member] | Subsequent Event [Member]
Subsidiary, Sale of Stock [Line Items]
Reverse stock split, conversion ratio7.4771
Description of the reverse stock split arrangementOn July 31, 2020, the Company effected a one-for-7.4771 reverse stock split of its common stock. Upon the effectiveness of the reverse stock split, (i) all shares of outstanding common stock were adjusted; (ii) the number of shares of common stock for which each outstanding option to purchase common stock is exercisable were adjusted; and (iii) the exercise price of each outstanding option to purchase common stock were adjusted. All of the outstanding common stock share numbers (including shares of common stock subject to the Company's options and as converted for the outstanding convertible preferred stock shares), share prices, exercise prices and per share amounts contained in the interim unaudited condensed financial statements have been retroactively adjusted in the interim condensed financial statements to reflect this reverse stock split for all periods presented. The par value per share and the authorized number of shares of common stock were not adjusted as a result of the reverse stock split. The reverse stock split resulted in an adjustment to the redeemable convertible preferred stock conversion prices to reflect a proportional decrease in the number of shares of common stock to be issued upon conversion.
Proceeds from initial public offering $ 67,000
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs $ 68,500
IPO [Member] | Common Stock [Member] | Subsequent Event [Member]
Subsidiary, Sale of Stock [Line Items]
Shares Issued During Period | shares5,000,000
Shares Issued, Price Per Share | $ / shares $ 15
Over-Allotment Option [Member] | Common Stock [Member] | Subsequent Event [Member]
Subsidiary, Sale of Stock [Line Items]
Shares Issued During Period | shares109,861
Sale of stock consideration received on the transaction $ 1,500

Fair Value Measurement - Schedu

Fair Value Measurement - Schedule of Fair Value Assets And Liabilities Measured On Recurring Basis (Detail) - USD ($) $ in ThousandsJun. 30, 2020Dec. 31, 2019
Assets:
Assets, Fair Value Disclosure $ 80,045 $ 4,003
Liabilities:
Financial Liabilities Fair Value Disclosure300
Money Market Funds [Member]
Assets:
Assets, Fair Value Disclosure80,045 4,003
Series B Preferred Stock Tranche Right Liability [Member]
Liabilities:
Financial Liabilities Fair Value Disclosure300
Fair Value, Inputs, Level 1 [Member]
Assets:
Assets, Fair Value Disclosure80,045 4,003
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets:
Assets, Fair Value Disclosure $ 80,045 4,003
Fair Value, Inputs, Level 3 [Member]
Liabilities:
Financial Liabilities Fair Value Disclosure300
Fair Value, Inputs, Level 3 [Member] | Series B Preferred Stock Tranche Right Liability [Member]
Liabilities:
Financial Liabilities Fair Value Disclosure $ 300

Fair Value Measurement - Sche_2

Fair Value Measurement - Schedule of Aggregate Fair Value of The Company's Series B Preferred Stock Tranche Right Liability (Detail) - USD ($) $ in Thousands6 Months Ended
Jun. 30, 2020Jun. 30, 2019
Schedule Of Aggregate fair value of the Companys series B preferred stock tranche right liability [Line Items]
Balance as of December 31, 2019 $ 300
Exercise of series B preferred stock tranche right300 $ 0
Series B Redeemable Convertible Preferred Stock [Member]
Schedule Of Aggregate fair value of the Companys series B preferred stock tranche right liability [Line Items]
Balance as of June 30, 2020300
Series B Redeemable Convertible Preferred Stock [Member] | Fair Value, Inputs, Level 3 [Member]
Schedule Of Aggregate fair value of the Companys series B preferred stock tranche right liability [Line Items]
Balance as of December 31, 2019300
Exercise of series B preferred stock tranche right(300)
Balance as of June 30, 2020 $ 0

Fair Value Measurement - Sche_3

Fair Value Measurement - Schedule of Fair Value, Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation (Detail) - USD ($) $ in Thousands6 Months Ended
Jun. 30, 2020Jun. 30, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Initial fair value $ 10,000 $ 0
Convertible Notes Payable [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Initial fair value10,000
Change in fair value plus accrued interest83
Settlement of convertible loan notes(10,083)
Ending balance $ 0

Fair Value Measurement - Additi

Fair Value Measurement - Additional Information (Details) - USD ($) $ / shares in Units, $ in ThousandsDec. 31, 2019Apr. 30, 2020Jun. 30, 2020Jun. 30, 2019Apr. 01, 2020
Fair Value Disclosures [Line Items]
Proceeds from convertible loan notes $ 10,000 $ 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Disclosures [Line Items]
Proceeds from convertible loan notes $ 10,000
Series B Redeemable Convertible Preferred Stock [Member]
Fair Value Disclosures [Line Items]
Fair value per share $ 2.20
Exercise date of preferred stock tranche rightJan. 14,
2020
Series C Redeemable Convertible Preferred Stock [Member]
Fair Value Disclosures [Line Items]
Debt instrument conversion price $ 1.6016
Series C Redeemable Convertible Preferred Stock [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Disclosures [Line Items]
Change in fair value of convertible notes $ 100

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in ThousandsJun. 30, 2020Dec. 31, 2019
Payables and Accruals [Abstract]
Payroll and employee related expenses $ 837 $ 1,051
External research and development2,572 1,969
Other accrued expenses327 80
Total accrued expenses $ 3,736 $ 3,100

Convertible Loan Notes - Additi

Convertible Loan Notes - Additional Information (Detail) - USD ($) $ in MillionsJun. 02, 2020Jun. 30, 2020Jun. 30, 2020Jun. 30, 2020Apr. 30, 2020Apr. 21, 2020
Convertible Notes Payable [Member]
Disclosure of Convertible Loan Notes [Line Items]
Debt Face Amount $ 10
Debt Instrument Interest Rate8.00%
Convertible Notes Payable [Member] | Fair Value, Inputs, Level 3 [Member]
Disclosure of Convertible Loan Notes [Line Items]
Gain loss on change in fair value of convertible notes $ 0.1 $ 0.1
Convertible Notes Payable [Member] | Debt Instrument Conversion Price Percentage One [Member]
Disclosure of Convertible Loan Notes [Line Items]
Debt instrument conversion price as a percentage of share price90.00%90.00%90.00%
Convertible Notes Payable [Member] | Debt Instrument Conversion Price Percentage One [Member] | Qualified Financing Period One [Member] | Maximum [Member]
Disclosure of Convertible Loan Notes [Line Items]
Term of qualified financing from the date of agreement for conversion price eligibility3 months
Convertible Notes Payable [Member] | Debt Instrument Conversion Price Percentage Two [Member]
Disclosure of Convertible Loan Notes [Line Items]
Debt instrument conversion price as a percentage of share price80.00%80.00%80.00%
Convertible Notes Payable [Member] | Debt Instrument Conversion Price Percentage Two [Member] | Qualified Financing Period Two [Member] | Maximum [Member]
Disclosure of Convertible Loan Notes [Line Items]
Term of qualified financing from the date of agreement for conversion price eligibility6 months
Convertible Notes Payable [Member] | Debt Instrument Conversion Price Percentage Two [Member] | Qualified Financing Period Two [Member] | Minimum [Member]
Disclosure of Convertible Loan Notes [Line Items]
Term of qualified financing from the date of agreement for conversion price eligibility3 months
Convertible Notes Payable [Member] | Debt Instrument Conversion Price Percentage Three [Member]
Disclosure of Convertible Loan Notes [Line Items]
Debt instrument conversion price as a percentage of share price70.00%70.00%70.00%
Convertible Notes Payable [Member] | Debt Instrument Conversion Price Percentage Three [Member] | Qualified Financing Period Three [Member]
Disclosure of Convertible Loan Notes [Line Items]
Term of qualified financing from the date of agreement for conversion price eligibility6 months
Series C Redeemable Convertible Preferred Stock [Member]
Disclosure of Convertible Loan Notes [Line Items]
Debt conversion, shares issued6,295,756
Series C Redeemable Convertible Preferred Stock [Member] | Convertible Notes Payable [Member]
Disclosure of Convertible Loan Notes [Line Items]
Debt Instrument benenficial conversion feature $ 10.1
Conversion price as a percentage of share price waived90.00%
Conversion price as a percentage of share price into which the debt instrument is converted100.00%

Redeemable Convertible Prefer_3

Redeemable Convertible Preferred Stock - Schedule of Redeemable Convertible Preferred Stock (Detail) - USD ($) $ in ThousandsJun. 30, 2020Dec. 31, 2019
Temporary Equity [Line Items]
Temporary equity number of shares issued108,096,207 51,283,386
Temporary equity number of shares outstanding108,096,207 51,283,386
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount $ 194,268 $ 96,928
Temporary equity liquidation preference $ 193,968 $ 96,928
Common stock issuable upon conversion14,948,249 7,289,543
Series A Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity number of shares issued25,000,000 25,000,000
Temporary equity number of shares outstanding25,000,000 25,000,000
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount $ 33,479 $ 32,482
Temporary equity liquidation preference $ 33,479 $ 32,482
Common stock issuable upon conversion3,343,542 3,343,542
Series B Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity number of shares issued29,972,284 26,283,386
Temporary equity number of shares outstanding29,972,284 26,283,386
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount $ 75,314 $ 64,446
Temporary equity liquidation preference $ 75,014 $ 64,446
Common stock issuable upon conversion4,499,824 3,946,001
Series C Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity number of shares issued53,123,923
Temporary equity number of shares outstanding53,123,923
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount $ 85,475
Temporary equity liquidation preference $ 85,475
Common stock issuable upon conversion7,104,883

Redeemable Convertible Prefer_4

Redeemable Convertible Preferred Stock - Schedule of Cumulative Dividends (Detail) - USD ($) $ in Thousands6 Months Ended12 Months Ended
Jun. 30, 2020Dec. 31, 2019
Series A Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Preferred stock amount of cumulative dividend $ 8,479 $ 7,482
Series B Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Preferred stock amount of cumulative dividend10,014 $ 7,446
Series C Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Preferred stock amount of cumulative dividend $ 392

Redeemable Convertible Prefer_5

Redeemable Convertible Preferred Stock - Additional Information (Detail)1 Months Ended6 Months Ended
Jun. 30, 2020USD ($)$ / sharessharesJan. 31, 2020$ / sharessharesJun. 30, 2020USD ($)$ / sharessharesJun. 30, 2019USD ($)Dec. 31, 2019USD ($)shares
Temporary Equity [Line Items]
Gross Proceeds from temporary equity $ 82,544,000 $ 10,949,000
Preferred stock tranche right liability current $ 300,000
Series A Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Preferred stock per share amount of cumulative dividend | $ / shares $ 0.08
Preferred stock dividend declared $ 0
Temporary equity shares authorised | shares25,000,000 25,000,000 25,000,000
Series B Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity issue price per share | $ / shares $ 2.16867
Net proceeds from temporary equity $ 8,000,000
Preferred stock per share amount of cumulative dividend | $ / shares $ 0.17349
Preferred stock dividend declared $ 0
Preferred stock tranche right liability current $ 300,000 $ 300,000
Temporary equity shares authorised | shares29,972,284 29,972,284 29,972,284
Temporary equity shares issued during the period | shares3,688,898
Series B Redeemable Convertible Preferred Stock [Member] | Conversion Ratio One [Member]
Temporary Equity [Line Items]
Conversion ratio of redeemable covertible preferred stock into common stock1 1
Series B Redeemable Convertible Preferred Stock [Member] | Conversion Ratio Two [Member]
Temporary Equity [Line Items]
Conversion ratio of redeemable covertible preferred stock into common stock0.15013 0.15013
Series B Redeemable Convertible Preferred Stock [Member] | Conversion Price One [Member]
Temporary Equity [Line Items]
Redeemable convertible preferred stock conversion price | $ / shares $ 16.21536 $ 16.21536
Series B Redeemable Convertible Preferred Stock [Member] | Conversion Price Two [Member]
Temporary Equity [Line Items]
Redeemable convertible preferred stock conversion price | $ / shares14.4451 14.4451
Series C Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity issue price per share | $ / shares $ 1.6016 1.6016
Preferred stock per share amount of cumulative dividend | $ / shares $ 0.128128
Preferred stock dividend declared $ 0
Temporary equity shares authorised | shares62,489,557 62,489,557
Series C Redeemable Convertible Preferred Stock [Member] | Series C Preferred Stock Purchase Agreement [Member]
Temporary Equity [Line Items]
Temporary equity issue price per share | $ / shares $ 1.6016 $ 1.6016
Gross Proceeds from temporary equity $ 75,000,000
Temporary equity shares authorised | shares62,489,557 62,489,557
Temporary equity shares issued during the period | shares46,828,167
Temporary equity unamortised stock issuance costs $ 400,000 $ 400,000
Series C Redeemable Convertible Preferred Stock [Member] | Series C Preferred Stock Purchase Agreement [Member] | Convertible Notes Payable [Member] | Unsecured Debt [Member]
Temporary Equity [Line Items]
Temporary equity shares issued during the period | shares6,295,756
Debt instrument converted value In excess of principal $ 100,000
Debt conversion original debt amount10,000,000
Temporary equity shares issued during the period $ 85,100,000

Common Stock - Summary of Commo

Common Stock - Summary of Common Stock Available for Future Issuance (Detail) - sharesJun. 30, 2020Dec. 31, 2019
Disclosure of Common Stock Summary of Outstanding and Reserved for Future Issuance [Line Items]
Common stock authorized146,000,000 76,000,000
Common stock issued1,488,489 1,488,489
Common stock outstanding1,488,489 1,488,489
Common stock authorized and reserved for future issuance14,948,249 7,289,543
Total common stock authorized and reserved for future issuance18,239,357
Unreserved common stock available for future issuance127,760,643
Employee Stock Option [Member]
Disclosure of Common Stock Summary of Outstanding and Reserved for Future Issuance [Line Items]
Common stock authorized and reserved for future issuance1,073,044
Share-based Payment Arrangement [Member]
Disclosure of Common Stock Summary of Outstanding and Reserved for Future Issuance [Line Items]
Common stock authorized and reserved for future issuance729,575
Series A Redeemable Convertible Preferred Stock [Member]
Disclosure of Common Stock Summary of Outstanding and Reserved for Future Issuance [Line Items]
Common stock authorized and reserved for future issuance3,343,542 3,343,542
Series B Redeemable Convertible Preferred Stock [Member]
Disclosure of Common Stock Summary of Outstanding and Reserved for Future Issuance [Line Items]
Common stock authorized and reserved for future issuance4,499,824 3,946,001
Series C Redeemable Convertible Preferred Stock [Member]
Disclosure of Common Stock Summary of Outstanding and Reserved for Future Issuance [Line Items]
Common stock authorized and reserved for future issuance7,104,883

Stock based compensation - Sche

Stock based compensation - Schedule of fair value of stock option awards on the grant date using the Black-Scholes option valuation model (Detail)6 Months Ended
Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk-free interest rate1.30%
Expected term (in years)5 years 9 months
Expected volatility70.00%
Dividend yield0.00%

Stock based compensation - Summ

Stock based compensation - Summary the activity under the Company's stock option plan (Detail) $ / shares in Units, $ in Thousands6 Months Ended12 Months Ended
Jun. 30, 2020USD ($)$ / sharessharesDec. 31, 2019USD ($)$ / sharesshares
Share-based Payment Arrangement [Abstract]
Outstanding Number, Beginning balance | shares1,073,044
Outstanding Number, Granted | shares0
Outstanding Number, Forfeited | shares0
Outstanding Number ,Exercised | shares0
Outstanding Number , Ending balance | shares1,073,044 1,073,044
Outstanding Number, Vested and expected to vest | shares1,073,044
Outstanding Number, Exercisable | shares426,980
Weighted Average Exercise price, Beginning balance | $ / shares $ 2.45
Weighted Average Exercise price, Granted | $ / shares0
Weighted Average Exercise price, Forfeited | $ / shares0
Weighted Average Exercise price, Exercised | $ / shares0
Weighted Average Exercise price, Ending balance | $ / shares2.45 $ 2.45
Weighted Average Exercise price, Vested and expected to vest | $ / shares2.45
Weighted Average Exercise price, Exercisable | $ / shares $ 2.23
Weighted-Average Remaining Contractual Term8 years 2 months 12 days8 years 8 months 12 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest8 years 2 months 12 days
Weighted-Average Remaining Contractual Term, Exercisable7 years 7 months 6 days
Aggregate Intrinsic Value | $ $ 906 $ 906
Aggregate Intrinsic Value, Vested and expected to vest | $906 $ 906
Aggregate Intrinsic Value, Exercisable | $ $ 468

Stock based compensation - Su_2

Stock based compensation - Summary of total stock-based compensation expense (Details) - USD ($) $ in Thousands3 Months Ended6 Months Ended
Jun. 30, 2020Jun. 30, 2019Jun. 30, 2020Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense $ 100 $ 78 $ 201 $ 157
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense39 25 78 49
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense $ 61 $ 53 $ 123 $ 108

Stock based compensation - Add

Stock based compensation - Additional information (Detail) - USD ($)Aug. 31, 2015Jun. 30, 2020Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options exercised0
Stock options granted gross0
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU's granted0
RSU's vested0
Two Thousand And Fifteen Stock Option And Grant Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards, vesting period4 years
Share-based Payment Award, Number of Shares Available for Issuance729,575 729,575
Unrecognized compensation expense related to stock option $ 0.95 $ 0.95
Unrecognized compensation expense expected to be recognized, Weighted average period2 years 7 months 6 days
Options exercised0
Stock options granted gross0 0
Weighted average grant date fair value of stock options granted, fair value $ 1.61 $ 1.61
Two Thousand And Fifteen Stock Option And Grant Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Award, Number of Shares Authorized for Issuance2,025,764

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail)6 Months Ended
Jun. 30, 2020
Taxable Years Beginning After January 2021 [Member]
Income Tax Disclosure [Line Items]
Percentage of net operating losses eligible for deduction80.00%

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Basic And Diluted Net Loss Per Share Attributable To Common Stockholders (Detail) - USD ($) $ / shares in Units, $ in Thousands3 Months Ended6 Months Ended
Jun. 30, 2020Jun. 30, 2019Jun. 30, 2020Jun. 30, 2019
Earnings Per Share [Abstract]
Net loss $ (8,348) $ (6,897) $ (16,149) $ (14,090)
Accretion of issuance costs related to redeemable convertible preferred stock(429)(33)(456)(51)
Accrued dividends on redeemable convertible preferred stock(2,187)(1,476)(3,957)(2,728)
Net loss attributable to common stockholders $ (10,964) $ (8,406) $ (20,562) $ (16,869)
Weighted-average common shares outstanding—basic and diluted1,488,489 1,429,484 1,488,489 1,413,935
Net loss per share attributable to common stockholders—basic and diluted $ (7.37) $ (5.88) $ (13.81) $ (11.93)

Net Loss Per Share - Summary _2

Net Loss Per Share - Summary of Potentially Dilutive Shares Excluded From The Calculation of Diluted Net Loss (Detail) - shares6 Months Ended
Jun. 30, 2020Jun. 30, 2019
Options to purchase common stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount1,073,044 812,539
Unvested restricted common stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount5,376
Redeemable convertible preferred stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount14,948,249 6,365,368

Commitments And Contingencies -

Commitments And Contingencies - Additional information (Detail) - USD ($) $ in ThousandsMar. 04, 2019Jun. 30, 2015Jun. 30, 2020Jun. 30, 2019Jun. 30, 2020Jun. 30, 2019Jun. 30, 2018Jun. 30, 2016Jun. 30, 2015
Long-term Purchase Commitment [Line Items]
Research and development expenses recognised $ 6,476 $ 5,849 $ 12,789 $ 12,049
Operating lease rental expenses100 $ 100 300 $ 200
CTSA Agreement [Member] | Research and Development Arrangement [Member]
Long-term Purchase Commitment [Line Items]
CTCSA agreement, commitment amount $ 4,000
Research and development costs and expenses Incurred500 100
Kuros Agreement commitment amount $ 4,000
CTSA Agreement [Member] | Research and Development Arrangement [Member] | Pfizer [Member]
Long-term Purchase Commitment [Line Items]
Research and development costs and expenses Incurred $ 0 0
Kuros License Agreement [Member]
Long-term Purchase Commitment [Line Items]
CTCSA agreement, commitment amount $ 56,000
Kuros Agreement commitment amount56,000
Milestone Payments Paid $ 2,300
Kuros License Agreement [Member] | Phase one Trail [Member]
Long-term Purchase Commitment [Line Items]
CTCSA agreement, commitment amount2,000
Kuros Agreement commitment amount2,000
Kuros License Agreement [Member] | Phase Two Trial [Member]
Long-term Purchase Commitment [Line Items]
CTCSA agreement, commitment amount4,000
Kuros Agreement commitment amount $ 4,000
Kuros License Agreement [Member] | License [Member]
Long-term Purchase Commitment [Line Items]
Research and development expenses recognised $ 1,000
Kuros License Agreement [Member] | Technology Service [Member] | Phase one Trail [Member]
Long-term Purchase Commitment [Line Items]
Research and development expenses recognised $ 1,000
Kuros License Second Amendment Agreement [Member]
Long-term Purchase Commitment [Line Items]
Research and development expenses recognised $ 0
Kuros License Second Amendment Agreement [Member] | License [Member]
Long-term Purchase Commitment [Line Items]
Research and development expenses recognised $ 300

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - sharesJan. 01, 2021Aug. 31, 2020Jun. 30, 2020Dec. 31, 2019Aug. 31, 2015
Shares of common stock reserved for issuance under 2015 plan14,948,249 7,289,543
2015 Stock Option and Grant Plan [Member]
Share-based Payment Award, Number of Shares Available for Issuance729,575
Maximum [Member] | 2015 Stock Option and Grant Plan [Member]
Share-based Payment Award, Number of Shares Authorized for Issuance2,025,764
Subsequent Event [Member] | 2020 Stock Option and Grant Plan [Member]
Share-based Payment Award, Number of Shares Available for Issuance3,205,430
Share-based Payment Award, Percentage of Outstanding Stock Maximum4.00%
Subsequent Event [Member] | 2015 Stock Option and Grant Plan [Member]
Share-based Payment Award, Number of Shares Available for Issuance729,575
Subsequent Event [Member] | 2020 Employee Stock Purchase Plan [Member]
Discount on purchase85.00%
Shares of common stock reserved for issuance under 2015 plan267,119
Subsequent Event [Member] | Maximum [Member] | 2020 Stock Option and Grant Plan [Member]
Share-based Payment Award, Number of Shares Authorized for Issuance3,935,005
Subsequent Event [Member] | Maximum [Member] | 2020 Employee Stock Purchase Plan [Member]
Discount on purchase15.00%