Repare Therapeutics (RPTX) 10-Q 10 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 10, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Trading Symbol	RPTX
Entity Registrant Name	Repare Therapeutics Inc.
Entity Central Index Key	0001808158
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		41,735,057
Title of 12(b) Security	Common shares, no par value
Security Exchange Name	NASDAQ
Entity File Number	001-39335
Entity Incorporation, State or Country Code	A8
Entity Tax Identification Number	00-0000000
Entity Address, Address Line One	7210 Frederick-Banting
Entity Address, Address Line Two	Suite 100
Entity Address, City or Town	St-Laurent
Entity Address, State or Province	QC
Entity Address, Country	CA
Entity Address, Postal Zip Code	H4S 2A1
City Area Code	857
Local Phone Number	412-7018
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 260,995	$ 326,184
Marketable securities	7,194	7,526
Research and development tax credits receivable	2,317	2,011
Other receivables	767	4,153
Prepaid expenses	9,103	6,678
Total current assets	280,376	346,552
Property and equipment, net	4,165	3,948
Restricted cash		212
Operating lease right-of-use assets	7,253	4,674
Other assets	1,008	288
Deferred tax assets	2,843	1,412
TOTAL ASSETS	295,645	357,086
CURRENT LIABILITIES:
Accounts payable	1,860	2,251
Accrued expenses and other current liabilities	11,020	5,975
Operating lease liability, current portion	1,458	697
Deferred revenue, current portion	8,925	2,073
Income tax payable	147	18
Total current liabilities	23,410	11,014
Operating lease liability, net of current portion	5,623	3,308
Deferred revenue, net of current portion	48,359	55,934
TOTAL LIABILITIES	77,392	70,256
SHAREHOLDERS’ EQUITY
Preferred shares, no par value per share; unlimited shares authorized as of September 30, 2021 and December 31, 2020, respectively; 0 shares issued and outstanding as of September 30, 2021, and December 31, 2020, respectively
Common shares, no par value per share; unlimited shares authorized as of September 30, 2021 and December 31, 2020; 37,133,938 and 36,902,924 shares issued and outstanding as of September 30, 2021 and December 31, 2020, respectively	385,990	384,313
Additional paid-in capital	14,239	5,875
Accumulated deficit	(181,976)	(103,358)
Total shareholders’ equity	218,253	286,830
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$ 295,645	$ 357,086

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Preferred stock par value	$ 0	$ 0
Preferred stock shares authorized	Unlimited	Unlimited
Preferred stock shares issued	0	0
Preferred stock shares outstanding	0	0
Common stock par value	$ 0	$ 0
Common stock shares authorized	Unlimited	Unlimited
Common stock shares issued	37,133,938	36,902,924
Common stock shares outstanding	37,133,938	36,902,924

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue:
Collaboration agreements	$ 278		$ 723
Operating expenses:
Research and development, net of tax credits	25,361	$ 10,091	62,075	$ 27,674
General and administrative	6,596	3,996	18,574	9,551
Total operating expenses	31,957	14,087	80,649	37,225
Loss from operations	(31,679)	(14,087)	(79,926)	(37,225)
Other income (expense), net
Realized and unrealized gain (loss) on foreign exchange	33	290	(92)	(846)
Interest income	53	156	155	156
Other expense	(7)	(4)	(21)	(10)
Total other income (expense), net	79	442	42	(700)
Loss before income taxes	(31,600)	(13,645)	(79,884)	(37,925)
Income tax recovery (expense)	708	(106)	1,266	(229)
Net loss and comprehensive loss	(30,892)	(13,751)	(78,618)	(38,154)
Net loss attributable to common shareholders—basic and diluted	$ (30,892)	$ (13,751)	$ (78,618)	$ (38,154)
Net loss per share attributable to common shareholders—basic and diluted	$ (0.83)	$ (0.37)	$ (2.12)	$ (2.63)
Weighted-average common shares outstanding—basic and diluted	37,122,668	36,756,694	37,026,116	14,486,896

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Convertible Preferred Shares and Shareholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Initial Public Offering	2020 Employee Share Purchase Plan	Series A Convertible Preferred Shares	Series B Convertible Preferred Shares	Common Shares	Common SharesInitial Public Offering	Common Shares2020 Employee Share Purchase Plan	Additional Paid-in Capital	Additional Paid-in Capital2020 Employee Share Purchase Plan	Accumulated Deficit
Balance at Dec. 31, 2019	$ (46,129)					$ 1			$ 3,811		$ (49,941)
Temporary equity balance, Shares at Dec. 31, 2019				11,090,135	10,468,258
Temporary equity balance, Value at Dec. 31, 2019				$ 53,749	$ 82,248
Balance, Shares at Dec. 31, 2019						1,528,374
Exercise of stock options	324					$ 520			(196)
Exercise of stock options, Shares						181,318
Share-based compensation expense	271								271
Net loss and comprehensive loss	(12,601)										(12,601)
Balance at Mar. 31, 2020	(58,135)					$ 521			3,886		(62,542)
Temporary equity balance, Shares at Mar. 31, 2020				11,090,135	10,468,258
Temporary equity balance, Value at Mar. 31, 2020				$ 53,749	$ 82,248
Balance, Shares at Mar. 31, 2020						1,709,692
Balance at Dec. 31, 2019	$ (46,129)					$ 1			3,811		(49,941)
Temporary equity balance, Shares at Dec. 31, 2019				11,090,135	10,468,258
Temporary equity balance, Value at Dec. 31, 2019				$ 53,749	$ 82,248
Balance, Shares at Dec. 31, 2019						1,528,374
Exercise of stock options, Shares	278,246
Issuance of warrant and conversion into common shares,Value	$ 15,000
Net loss and comprehensive loss	(38,154)
Balance at Sep. 30, 2020	300,798					$ 383,852			5,041		(88,095)
Balance, Shares at Sep. 30, 2020						36,765,013
Balance at Mar. 31, 2020	(58,135)					$ 521			3,886		(62,542)
Temporary equity balance, Shares at Mar. 31, 2020				11,090,135	10,468,258
Temporary equity balance, Value at Mar. 31, 2020				$ 53,749	$ 82,248
Balance, Shares at Mar. 31, 2020						1,709,692
Exercise of stock options	164					$ 257			(93)
Exercise of stock options, Shares						85,369
Share-based compensation expense	389								389
Issuance of common shares		$ 232,043					$ 232,043
Issuance of common shares, Shares							12,650,000
Conversion of convertible preferred shares into an equivalent number of common shares, Value	135,997			$ (53,749)	$ (82,248)	$ 135,997
Conversion of convertible preferred shares into an equivalent number of common shares, Shares				(11,090,135)	(10,468,258)	21,558,393
Issuance of warrant and conversion into common shares,Value	15,000					$ 15,000
Issuance of warrant and conversion into common shares, Shares						750,000
Net loss and comprehensive loss	(11,802)										(11,802)
Balance at Jun. 30, 2020	313,656					$ 383,818			4,182		(74,344)
Balance, Shares at Jun. 30, 2020						36,753,454
Exercise of stock options	22					$ 34			(12)
Exercise of stock options, Shares						11,559
Share-based compensation expense	871								871
Net loss and comprehensive loss	(13,751)										(13,751)
Balance at Sep. 30, 2020	300,798					$ 383,852			5,041		(88,095)
Balance, Shares at Sep. 30, 2020						36,765,013
Balance at Dec. 31, 2020	286,830					$ 384,313			5,875		(103,358)
Balance, Shares at Dec. 31, 2020						36,902,924
Exercise of stock options	183					$ 297			(114)
Exercise of stock options, Shares						87,786
Share-based compensation expense	2,057								2,057
Net loss and comprehensive loss	(21,417)										(21,417)
Balance at Mar. 31, 2021	267,653					$ 384,610			7,818		(124,775)
Balance, Shares at Mar. 31, 2021						36,990,710
Balance at Dec. 31, 2020	$ 286,830					$ 384,313			5,875		(103,358)
Balance, Shares at Dec. 31, 2020						36,902,924
Exercise of stock options, Shares	217,772
Net loss and comprehensive loss	$ (78,618)
Balance at Sep. 30, 2021	218,253					$ 385,990			14,239		(181,976)
Balance, Shares at Sep. 30, 2021						37,133,938
Balance at Mar. 31, 2021	267,653					$ 384,610			7,818		(124,775)
Balance, Shares at Mar. 31, 2021						36,990,710
Exercise of stock options	449					$ 731			(282)
Exercise of stock options, Shares						115,497
Share-based compensation expense	3,183								3,183
Issuance of common shares	113					$ 113
Issuance of common shares, Shares						3,299
Net loss and comprehensive loss	(26,309)										(26,309)
Balance at Jun. 30, 2021	245,089					$ 385,454			10,719		(151,084)
Balance, Shares at Jun. 30, 2021						37,109,506
Exercise of stock options	80					$ 129			(49)
Exercise of stock options, Shares						14,489
Share-based compensation expense	3,693								3,693
Issuance of common shares under the 2020 Employee Share Purchase Plan			$ 283					$ 407		$ 124
Issuance of common shares under the 2020 Employee Share Purchase Plan, Shares								9,943
Net loss and comprehensive loss	(30,892)										(30,892)
Balance at Sep. 30, 2021	$ 218,253					$ 385,990			$ 14,239		$ (181,976)
Balance, Shares at Sep. 30, 2021						37,133,938

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Convertible Preferred Shares and Shareholders' Equity (Deficit) (Parenthetical) (Unaudited) $ in Thousands	3 Months Ended
	Jun. 30, 2020USD ($)
Initial Public Offering
Stock issuance costs	$ 20,957

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash Flows From Operating Activities:
Net loss and comprehensive loss for the period	$ (78,618)	$ (38,154)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	8,933	1,531
Depreciation expense	1,103	610
Non-cash lease expense	1,248	520
Foreign exchange loss	10	835
Amortization of premiums on marketable securities	85
Deferred tax	(1,431)	(86)
Changes in operating assets and liabilities:
Prepaid expenses	(2,425)	(8,834)
Research and development tax credits receivable	(295)	(584)
Other receivables	3,429	(1,283)
Other non-current assets	(616)	71
Accounts payable	(295)	(1,120)
Accrued expenses and other current liabilities	5,166	3,540
Operating lease liability, current portion	(174)	(97)
Income tax payable	129	265
Operating lease liability, net of current portion	(584)	(351)
Deferred revenue	(723)	50,000
Net cash (used in) provided by operating activities	(65,058)	6,863
Cash Flows From Investing Activities:
Purchases of property and equipment	(1,525)	(516)
Proceeds from maturities of marketable securities	5,450
Purchase of marketable securities	(5,203)
Net cash used in investing activities	(1,278)	(516)
Cash Flows From Financing Activities:
Proceeds from exercise of stock options	712	510
Proceeds from issuance of common stock under the 2020 Employee Share Purchase Plan	283
Proceeds from issuance of warrant		15,000
Net proceeds from issuance of common shares in initial public offering		232,043
Net cash provided by financing activities	995	247,553
Effect of exchange rate fluctuations on cash held	(60)	(830)
Net (Decrease) Increase In Cash And Cash Equivalents And Restricted Cash	(65,401)	253,070
Cash and cash equivalents and restricted cash at beginning of period	326,396	95,005
Cash and cash equivalents and restricted cash at end of period	260,995	348,075
Reconciliation Of Cash And Cash Equivalents And Restricted Cash
Cash and cash equivalents	260,995	347,872
Restricted cash		203
Total cash and cash equivalents and restricted cash	260,995	348,075
Supplemental Disclosure Of Cash Flow Information:
Property and equipment purchases in incurred but not yet paid	13	950
Right-of-use asset obtained in exchange for new operating lease liability	3,827	4,516
Deferred Financing Costs In Accruals And Other Current Liabilities	$ 104
Conversion of Series A and B convertible preferred shares into common shares		135,997
Issuance of warrant and conversion into common shares,Value		$ 15,000

Organization and Nature of Busi

Organization and Nature of Business	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Nature of Business	REPARE THERAPEUTICS INC. NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (Amounts in U.S. dollars, unless otherwise specified) 1. Organization and Nature of Business Repare Therapeutics Inc. (“Repare” or the “Company”) is a precision medicine oncology company focused on the development of synthetic lethality-based therapies to patients with cancer. The Company was incorporated under the Canada Business Corporations Act on September 6, 2016 . On June 23, 2020, immediately prior to the completion of its initial public offering (the “IPO”), the Company was continued as a corporation under the Business Corporations Act (Québec) . On June 23, 2020, the Company completed its IPO of 12,650,000 of its common shares, including the exercise in full by the underwriters of their option to purchase up to 1,650,000 additional common shares, for aggregate gross proceeds of $ 253.0 million. The Company’s shares began trading on the Nasdaq Global Select Market under the ticker symbol “RPTX” on June 19, 2020. The Company received $ 232.0 million in net proceeds after deducting underwriting commissions and other offering expenses payable by the Company. Upon closing of the IPO, all outstanding convertible preferred shares converted into 21,558,393 common shares and the outstanding warrant was automatically exercised into 750,000 common shares.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and as amended by Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). The unaudited condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements as of and for the year ended December 31, 2020, and, in the opinion of management, reflect all adjustments, consisting of normal recurring adjustments, necessary for the fair presentation of the Company’s consolidated financial position as of September 30, 2021, the consolidated results of its operations for the three and nine months ended September 30, 2021 and 2020, its statements of shareholders’ equity (deficit) for the three and nine months ended September 30, 2021 and 2020 and its consolidated cash flows for the nine months ended September 30, 2021 and 2020. These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the accompanying notes for the year ended December 31, 2020 included in the Company’s Annual Report on Form 10-K, filed with the Securities and Exchange Commission (the “SEC”) on March 4, 2021 (the “Annual Report”). The condensed consolidated balance sheet data as of December 31, 2020 presented for comparative purposes was derived from the Company’s audited consolidated financial statements but does not include all disclosures required by U.S. GAAP. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of the operating results to be expected for the full year or for any other subsequent interim period. The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2020 included in the Annual Report. Since the date of the audited consolidated financial statements for the year ended December 31, 2020 included in the Annual Report, there have been no changes to its significant accounting policies, except for a new standard effective January 1, 2021 as described below. Principles of Consolidation These unaudited condensed consolidated financial statements of the Company include the accounts of the Company and its wholly-owned subsidiary, Repare Therapeutics USA Inc. (“Repare USA”), which was incorporated under the laws of Delaware on June 1, 2017. The financial statements of Repare USA are prepared for the same reporting period as the parent company, using consistent accounting policies. All intra-group transactions, balances, income, and expenses are eliminated in full upon consolidation. Emerging Growth Company Status The Company is an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act, or JOBS Act, and may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. Section 107 of the JOBS Act provides that an emerging growth company can take advantage of the extended transition period afforded by the JOBS Act for the implementation of new or revised accounting standards. The Company has elected to use the extended transition period for complying with new or revised accounting standards and as a result of this election, its consolidated financial statements may not be comparable to companies that comply with public company effective dates. Because the market value of its common shares held by non-affiliates exceeded $700 million as of June 30, 2021, the Company will be deemed a large accelerated filer under the Exchange Act and will lose its status as an “emerging growth company” as of December 31, 2021. The Company will no longer be able to avail itself of such extended transition period for compliance with new or revised accounting standards as of December 31, 2021. Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes - Simplifying the Accounting for Income Taxes (“ASU No. 2019-12”). ASU No. 2019-12 eliminates certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The new guidance also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. For public entities, ASU No. 2019-12 is effective for annual periods beginning after December 15, 2020, including interim periods within. For all other entities, this pronouncement is effective for fiscal years beginning after December 15, 2021, including interim periods within fiscal years beginning after December 15, 2022. Early adoption is permitted for all entities. Adoption of the standard requires certain changes to be made prospectively, with some changes to be made retrospectively. The adoption of ASU No. 2019-12 did not have a material impact on the Company’s unaudited condensed consolidated financial statements. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in consolidated financial statements and accompanying notes. Significant estimates and assumptions reflected in these unaudited condensed consolidated financial statements include, but are not limited to, estimates related to revenue recognition, accrued research and development expenses, share-based compensation, right-of-use assets and lease liabilities and income taxes. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. 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 could materially differ from those estimates. Changes in estimates are recorded in the period in which they become known. COVID-19 Pandemic With the global spread of the ongoing COVID-19 pandemic, including variants of COVID-19, the Company established a cross-functional task force and has implemented business continuity plans designed to address and mitigate the impact of the COVID-19 pandemic on its employees and its business, including its preclinical studies and its ongoing and planned clinical trials. The Company has taken measures to secure its research and development activities, while work in its laboratories and facilities has been re-organized to reduce risk of COVID-19 transmission. While the Company is experiencing limited financial impacts at this time, given the global economic slowdown, the overall disruption of global healthcare systems and the other risks and uncertainties associated with the pandemic, the Company’s business, financial condition, and results of operations could be materially adversely affected. The Company cannot predict the ultimate impact, if any, of COVID-19 related to both known and unknown risks, including future quarantines, closures and other restrictions resulting from the outbreak. The Company continues to closely monitor the COVID-19 pandemic as it evolves its business continuity plans, clinical development plans and response strategy. As of the date of these financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. Actual results could differ from these estimates, and any such differences may be material to the Company’s consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The following table presents information about the Company’s financial assets measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values as of September 30, 2021 and December 31, 2020: Description Financial Assets Quoted Significant Significant (in thousands) As at September 30, 2021 Assets Cash equivalents Money market funds $ 2,774 $ 2,774 $ — $ — Marketable securities U.S. Treasury notes 7,194 7,194 — — Total financial assets $ 9,968 $ 9,968 $ — $ — As at December 31, 2020 Assets Cash equivalents Money market funds $ 2,455 $ 2,455 $ — $ — Marketable securities U.S. Treasury notes 7,526 7,526 — — Total financial assets $ 9,981 $ 9,981 $ — $ — When developing fair value estimates, the Company maximizes the use of observable inputs and minimizes the use of unobservable inputs. When available, the Company uses quoted market prices to measure the fair value. The valuation technique used to measure fair value for the Company’s Level 1 assets is a market approach, using prices and other relevant information generated by market transactions involving identical or comparable assets. If market prices are not available, the fair value measurement is based on models that use primarily market-based parameters including yield curves, volatilities, credit ratings and currency rates. In certain cases where market rate assumptions are not available, the Company is required to make judgements about assumptions market participants would use to estimate the fair value of a financial instrument. During the nine months ended September 30, 2021 , there were no transfers between fair value measure levels.

Cash and Cash Equivalents and M

Cash and Cash Equivalents and Marketable Securities	9 Months Ended
	Sep. 30, 2021
Investments Debt And Equity Securities [Abstract]
Cash and Cash Equivalents and Marketable Securities	4. Cash and Cash Equivalents and Marketable Securities As of September 30, 2021 and December 31, 2020, cash and cash equivalents and marketable securities were comprised of the following: Amortized Cost Unrealized Gains Unrealized Losses Fair Value (in thousands) As at September 30, 2021 Money market funds included in cash and $ 2,774 $ — $ — $ 2,774 Marketable securities: U.S. Treasury notes 7,194 — — 7,194 Total $ 9,968 $ — $ — $ 9,968 As at December 31, 2020 Money market funds included in cash and $ 2,455 $ — $ — $ 2,455 Marketable securities: U.S. Treasury notes 7,526 — — 7,526 Total $ 9,981 $ — $ — $ 9,981 The amortized cost of marketable securities at September 30, 2021 is equal to their fair value. Accordingly, no unrealized gains or losses were recognized in the nine months ended September 30, 2021. The maturities of the Company’s money market funds included in cash and cash equivalents, and marketable securities is less than one year.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2021
Payables And Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	5 . Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities as of September 30, 2021 and December 31, 2020 consisted of the following: September 30, December 31, (in thousands) Accrued compensation and benefits $ 3,361 $ 2,771 Accrued research and development expense 6,808 2,584 Accrued professional services 456 436 Other 395 184 Total accrued expenses and other current liabilities $ 11,020 $ 5,975

Collaboration and License Agree

Collaboration and License Agreement	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaboration and License Agreement	6. Collaboration and License Agreement In May 2020, the Company entered into a collaboration and license agreement with Bristol-Myers Squibb Company (“Bristol Myers Squibb”), pursuant to which the Company and Bristol Myers Squibb have agreed to collaborate in the research and development of potential new product candidates for the treatment of cancer (the “BMS Agreement”). The Company is providing Bristol Myers Squibb access to a selected number of its existing screening campaigns and novel campaigns. The Company is responsible for carrying out early-stage research activities directed to identifying potential targets for potential licensing by Bristol Myers Squibb, in accordance with a mutually agreed upon research plan, and will be solely responsible for such costs. The collaboration consists of programs directed to both druggable targets and to targets commonly considered undruggable to traditional small molecule approaches. Upon Bristol Myers Squibb’s election to exercise its option to obtain exclusive worldwide licenses for the subsequent development, manufacturing and commercialization of a program, Bristol Myers Squibb will then be solely responsible for all such worldwide activities and costs. The collaboration term will expire 42 months after the effective date of the BMS Agreement. The BMS Agreement will expire, assuming that Bristol Myers Squibb has exercised at least one option for a program, on a licensed product-by-licensed product and country-by-country basis on expiration of the applicable royalty term and in its entirety upon expiration of the last royalty term. Either party may terminate earlier upon an uncured material breach of the agreement by the other party, or the insolvency of the other party. Additionally, Bristol Myers Squibb may terminate the BMS Agreement for any or no reason on a program-by-program basis upon specified written notice. Under the terms of the BMS Agreement, Bristol Myers Squibb paid the Company an initial nonrefundable upfront fee of $ 50.0 million in June 2020. The Company is also entitled to receive up to $ 301.0 million in total milestones on a program-by-program basis, consisting of $ 176.0 million in the aggregate for certain specified research, development and regulatory milestones and $ 125.0 million in the aggregate for certain specified commercial milestones. The Company is further entitled to a tiered percentage royalty on annual net sales ranging from high-single digits to low-double digits, subject to certain specified reductions. The Company assessed the BMS Agreement in accordance with ASC 606, Revenue from Contracts with Customers, and concluded that Bristol Myers Squibb is a customer based on the agreement structure. At inception, the Company identified several performance obligations under the BMS Agreement, being (i) research activities for each campaign over the collaboration term, as well as (ii) a selected number of material rights associated with options to obtain exclusive development, manufacturing, and commercial licenses to targets identified. The Company determined that the options to obtain the exclusive development, manufacturing and commercialization licenses were material rights under ASC 606 because there are minimal amounts to be paid to the Company upon exercise of such options. The Company determined that the transaction price at the onset of the agreement is the total non-refundable upfront payment received of $ 50.0 million. Additional consideration is to be paid to the Company upon the exercise of options to license targets and future milestone payments. The Company utilized the most likely method approach and concluded that these amounts were constrained as they represent option fees and milestone payments that can only be achieved subsequent to option exercises. As such, the Company excluded this additional consideration from the transaction price. The Company has allocated the transaction price of $ 50.0 million to each performance obligation based on the relative stand-alone selling price of each performance obligation at inception, which was determined based on each performance obligation’s estimated stand-alone selling price. The Company has determined the estimated stand-alone selling price at contract inception of the research activities based on internal estimates of the costs to perform the services, inclusive of a reasonable profit margin. Significant inputs used to determine the total costs to perform the research activities included the length of time required, the internal hours expected to be incurred on the services and the number and costs of various studies that will be performed to complete the research plan. The Company determined the estimated stand-alone selling price at contract inception of the material rights associated with options to obtain exclusive licenses to druggable targets and undruggable targets based on the fees Bristol Myers Squibb would pay to exercise these options, the probability-weighted value of expected future cash flows associated with each license related to each target and the probability that these options would be exercised by Bristol Myers Squibb. In developing such estimates, the Company also considered applicable market conditions and relevant entity-specific factors, including those factors contemplated in negotiating the agreement, probability of success and the time needed to commercialize a product candidate pursuant to the associated license. Based on the relative stand-alone selling price, the allocation of the transaction price to the separate performance obligations was as follows: Performance obligation Transaction price (in thousands) Research services $ 6,405 Options to license druggable target lesions 31,148 Options to license undruggable targets 12,447 Total transaction price $ 50,000 Revenue associated with the options has been deferred and will be recognized at the point in time when options to license are exercised by Bristol Myers Squibb or upon expiry of such options. Revenue associated with the research activities has been deferred and will be recognized on a proportional performance basis over the period of service for research activities, being the collaboration term, using input-based measurements of total costs of research incurred to estimated proportion performed. Progress towards completion is remeasured at the end of each reporting period. The Company recognized $ 0.3 million and nil for the three months ended September 30, 2021 and 2020, respectively, and $ 0.7 million and nil for the nine months ended September 30, 2021 and 2020, respectively, as revenue associated with the BMS Agreement in relation to research activities performed to date. As of September 30, 2021, there was $ 49.1 million (December 31, 2020 - $ 49.9 million ) of deferred revenue related to the BMS Agreement, of which $ 8.9 million (December 31, 2020 - $ 2.1 million ) was classified as current and $ 40.2 million (December 31, 2020 - $ 47.8 million ) was classified as non-current in the consolidated balance sheet based on the period the services are expected to be performed and the expected timing of potential option exercises. As of September 30, 2021 , no options were exercised by Bristol Myers Squibb. In October 2021, the Company received notification from Bristol Myers Squibb of their option exercise for druggable targets directed at a synthetic lethal lesion, pursuant to the terms of the BMS Agreement. As a result, the Company expects to record approximately $ 6.5 million as revenue in the fourth quarter of 2021 with regards to the option fees to be received from Bristol Meyers Squibb and the achievement of the related performance obligation.

Leases

Leases	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Leases	7. Leases The Company has historically entered into lease arrangements for its facilities. As of September 30, 2021 , the Company had five operating leases with required future minimum payments. The Company’s leases generally do not include termination or purchase options. In May 2021, the Company amended the lease agreement initially entered in June 2019 for office space in Cambridge, Massachusetts, to extend the lease term until October 2021 . The amended agreement will result in $ 0.2 million of minimum lease payments over the five-month extended lease term. In August 2021, the Company further amended the lease agreement to extend the lease term until December 2021 . This second amendment will result in $ 0.1 million of minimum lease payments over the two-month extended lease term. In June 2021, the Company amended the lease agreement entered in June 2017 for office and laboratory space located in Montreal, Quebec, to extend the lease term until July 2025 . The amended agreement will result in $ 0.5 million of minimum lease payments over the extended four-year lease term. In July 2021, the Company entered into a new lease agreement for office space in Cambridge, Massachusetts. The agreement will result in $ 3.2 million of minimum lease payments over the three-year lease term. In July 2021, the Company amended the lease agreement entered in November 2019 for office and laboratory space located in Montreal, Quebec, to include additional office space. As of September 30, 2021, the amended agreement has not commenced, and is expected to result in $ 1.1 million of minimum lease payments over the remaining lease term . Operating Leases The following table contains a summary of the lease costs recognized under ASC 842 and other information pertaining to the Company’s operating leases for the three and nine months ended September 30, 2021 and 2020: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (in thousands) Operating Leases Lease Costs Operating lease costs $ 563 $ 249 $ 1,406 $ 579 Short-term lease costs 22 34 27 38 Variable lease costs 20 16 130 108 Total lease costs $ 605 $ 299 $ 1,563 $ 725 Nine Months Ended September 30, 2021 2020 (in thousands, except as specified otherwise) Other Operating Lease Information Operating cash flows used for operating leases $ 913 $ 513 Right-of-use assets obtained in exchange for new operating lease liability $ 3,827 $ 4,516 Weighted-average remaining lease term (in years) 3.51 4.37 Weighted-average discount rate 4.0 % 5.2 %

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	8. Share-Based Compensation 2020 Employee Share Purchase Plan In June 2020, the Company’s board of directors adopted, and the Company’s shareholders approved the 2020 Employee Share Purchase Plan (the “ESPP”). The maximum number of common shares that may be issued under the ESPP was initially 327,000 . Additionally, the number of shares reserved and available for issuance under the ESPP automatically increases each January 1, beginning on January 1, 2021 and each January 1 thereafter through January 31, 2030, by the lesser of (1) 1.0 % of the total number of common shares outstanding on December 31 of the preceding calendar year, (2) 3,300,000 common shares, or (3) such smaller number of common shares as the Company’s board of directors may designate. As of September 30, 2021 , the number of common shares that may be issued under the ESPP is 686,086 . The ESPP enables eligible employees to purchase common shares of the Company at the end of each offering period at a price equal to 85 % of the fair market value of the shares on the first business day or the last business day of the offering period, whichever is lower. Participation in the ESPP is voluntary. Eligible employees become participants in the ESPP by enrolling in the plan and authorizing payroll deductions. At the end of each offering period, payroll deductions that have accumulated are used to purchase shares of the Company’s shares at the discounted price. The Company makes no contributions to the ESPP. A participant may withdraw from the ESPP or suspend contributions to the ESPP. If the participant elects to withdraw during an offering, all contributions are refunded as soon as administratively practicable. If a participant elects to withdraw or suspend contributions, they will not be able to re-enroll in the current offering but may elect to participate in future offerings. The ESPP purchases only whole shares of the Company’s shares. The Company’s first ESPP offering period began February 16, 2021 and ended on August 15, 2021, with a second offering period commencing on August 16, 2021. Subsequent offering periods will be on a rolling six-month basis. As of September 30, 2021 , 9,943 common shares have been issued under the ESPP. Share-based compensation expense of $ 0.1 million in the three months ended September 30, 2021 and $ 0.1 million in the nine months ended September 30, 2021 was recorded in operating expenses. No share-based compensation expense was recorded in operating expenses in the three and nine months ended September 30, 2020. Option Plan and 2020 Plan In December 2016, as further amended in December 2017 and September 2019, the Company adopted the Repare Therapeutics Inc. Option Plan (the “Option Plan”) for the issuance of share options and other share-based awards to directors, officers, employees or consultants. The Option Plan authorized up to 4,074,135 shares of the Company’s common shares to be issued. In June 2020, the Company’s board of directors adopted, and the Company’s shareholders approved the 2020 Equity Incentive Plan (the “2020 Plan”). The 2020 Plan became effective on the effective date of the IPO, at which time the Company ceased granting awards under the Option Plan. The 2020 Plan allows the Company’s compensation committee to grant equity-based and cash-based incentive awards to the Company’s officers, employees, directors and consultants. A total of 3,600,000 common shares were initially reserved for issuance under the 2020 Plan, plus the number of shares (not to exceed 3,807,448 shares) consisting of (i) 298,605 common shares that were available for the issuance of awards under the Option Plan at the time the 2020 Plan became effective, which ceased to be available for future issuance under the Option Plan at such time and (ii) any shares subject to outstanding options or other share awards that were granted under the Option Plan that terminate or expire prior to exercise or settlement; are forfeited because of the failure to vest; or are reacquired or withheld (or not issued) to satisfy a tax withholding obligation or the purchase or exercise price. In addition, the number of shares reserved and available for issuance under the 2020 Plan automatically increases each January 1, beginning on January 1, 2021 and each January 1 thereafter through January 1, 2030, by 5 % of the outstanding number of common shares on the immediately preceding December 31, or such lesser number of shares as determined by the Company’s board of directors. As of September 30, 2021 , the number of common shares reserved for issuance under the 2020 Plan is 5,797,188 . Total outstanding stock options as of September 30, 2021 and 2020 were as follows: 2021 2020 Number of Weighted Number of Weighted Outstanding at beginning of period 4,132,123 $ 6.39 3,505,119 $ 2.07 Granted 1,426,616 $ 35.73 899,274 $ 16.61 Exercised ( 217,772 ) $ 3.28 ( 278,246 ) $ 1.83 Cancelled or forfeited ( 84,614 ) $ 26.95 ( 34,637 ) $ 1.96 Outstanding at end of period 5,256,353 $ 14.15 4,091,510 $ 5.28 During the nine months ended September 30, 2021, an aggregate of 217,772 options were exercised at a weighted-average exercise price of $ 3.28 per share, for aggregate proceeds of $ 0.7 million. As a result, an amount of $ 0.4 million previously included in additional paid-in capital related to the exercised options has been credited to common shares and deducted from additional paid-in capital. Share-based compensation expense was allocated as follows: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (in thousands) Research and development $ 1,512 $ 269 $ 3,865 $ 565 General and administrative $ 2,124 602 4,919 966 Total share-based compensation expense $ 3,636 $ 871 $ 8,784 $ 1,531 The fair value of stock options, and the assumptions used in the Black Scholes option-pricing model to determine the grant date fair value of stock options granted to employees and non-employees were as follows, presented on a weighted average basis: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Fair value of stock options $ 21.99 $ 14.42 $ 23.29 $ 10.43 Risk-free interest rate 0.98 % 0.43 % 0.73 % 0.43 % Expected terms (in years) 5.85 6.07 5.99 6.07 Expected volatility 76.10 % 71.30 % 75.61 % 71.99 % Expected dividend yield 0.00 % 0.00 % 0.00 % 0.00 % As of September 30, 2021 , there was $ 36.5 million of unrecognized share-based compensation expense related to unvested stock options to be recognized over a weighted average period of 2.2 years.

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss per Share	9. Net Loss per Share The following table summarizes the computation of basic and diluted net loss per share attributable to common shareholders of the Company: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (in thousands, except share and per share amounts) Numerator: Net loss attributable to common shareholders $ ( 30,892 ) $ ( 13,751 ) $ ( 78,618 ) $ ( 38,154 ) Net loss attributable to common shareholders—basic and diluted $ ( 30,892 ) $ ( 13,751 ) $ ( 78,618 ) $ ( 38,154 ) Denominator: Weighted-average number of common shares outstanding—basic 37,122,668 36,756,694 37,026,116 14,486,896 Net loss per share attributable to common shareholders—basic $ ( 0.83 ) $ ( 0.37 ) $ ( 2.12 ) $ ( 2.63 ) The Company’s potentially dilutive securities, which include options, have been excluded from the computation of diluted net loss per share attributable to common shareholders as the effect would be to reduce the net loss per share attributable to common shareholders. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common shareholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common shareholders for the periods indicated because including them would have had an anti-dilutive effect: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Options to purchase common shares 5,256,353 4,091,510 5,256,353 4,091,510

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	10. Subsequent Events a) On November 1, 2021, the Company completed a follow-on offering of 4,600,000 of its common shares, including the exercise in full by the underwriters of their option to purchase up to 600,000 additional common shares, at a public offering price of $ 22.00 per share, for net proceeds of approximately $ 93.9 million, after deducting underwriting commissions and estimated offering expenses of $ 1.2 million payable by the Company. b) On October 13, 2021, upon the occurrence of a specified research trigger, the Company became eligible to receive a portion, amounting to ¥ 100 million ($ 0.9 million), of the research service payments provided for in its research services, license and collaboration agreement with Ono Pharmaceutical Co., Ltd., or Ono, ("Ono Agreement") for the research of potential product candidates targeting Polθ . Furthermore, on October 29, the Company and Ono entered into an amendment to the Ono Agreement whereby the Research Term, as defined in the Ono Agreement, was extended by one year .

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and as amended by Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). The unaudited condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements as of and for the year ended December 31, 2020, and, in the opinion of management, reflect all adjustments, consisting of normal recurring adjustments, necessary for the fair presentation of the Company’s consolidated financial position as of September 30, 2021, the consolidated results of its operations for the three and nine months ended September 30, 2021 and 2020, its statements of shareholders’ equity (deficit) for the three and nine months ended September 30, 2021 and 2020 and its consolidated cash flows for the nine months ended September 30, 2021 and 2020. These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the accompanying notes for the year ended December 31, 2020 included in the Company’s Annual Report on Form 10-K, filed with the Securities and Exchange Commission (the “SEC”) on March 4, 2021 (the “Annual Report”). The condensed consolidated balance sheet data as of December 31, 2020 presented for comparative purposes was derived from the Company’s audited consolidated financial statements but does not include all disclosures required by U.S. GAAP. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of the operating results to be expected for the full year or for any other subsequent interim period. The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2020 included in the Annual Report. Since the date of the audited consolidated financial statements for the year ended December 31, 2020 included in the Annual Report, there have been no changes to its significant accounting policies, except for a new standard effective January 1, 2021 as described below.
Principles of Consolidation	Principles of Consolidation These unaudited condensed consolidated financial statements of the Company include the accounts of the Company and its wholly-owned subsidiary, Repare Therapeutics USA Inc. (“Repare USA”), which was incorporated under the laws of Delaware on June 1, 2017. The financial statements of Repare USA are prepared for the same reporting period as the parent company, using consistent accounting policies. All intra-group transactions, balances, income, and expenses are eliminated in full upon consolidation.
Emerging Growth Company Status	Emerging Growth Company Status The Company is an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act, or JOBS Act, and may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. Section 107 of the JOBS Act provides that an emerging growth company can take advantage of the extended transition period afforded by the JOBS Act for the implementation of new or revised accounting standards. The Company has elected to use the extended transition period for complying with new or revised accounting standards and as a result of this election, its consolidated financial statements may not be comparable to companies that comply with public company effective dates. Because the market value of its common shares held by non-affiliates exceeded $700 million as of June 30, 2021, the Company will be deemed a large accelerated filer under the Exchange Act and will lose its status as an “emerging growth company” as of December 31, 2021. The Company will no longer be able to avail itself of such extended transition period for compliance with new or revised accounting standards as of December 31, 2021.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes - Simplifying the Accounting for Income Taxes (“ASU No. 2019-12”). ASU No. 2019-12 eliminates certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The new guidance also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. For public entities, ASU No. 2019-12 is effective for annual periods beginning after December 15, 2020, including interim periods within. For all other entities, this pronouncement is effective for fiscal years beginning after December 15, 2021, including interim periods within fiscal years beginning after December 15, 2022. Early adoption is permitted for all entities. Adoption of the standard requires certain changes to be made prospectively, with some changes to be made retrospectively. The adoption of ASU No. 2019-12 did not have a material impact on the Company’s unaudited condensed consolidated financial statements.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in consolidated financial statements and accompanying notes. Significant estimates and assumptions reflected in these unaudited condensed consolidated financial statements include, but are not limited to, estimates related to revenue recognition, accrued research and development expenses, share-based compensation, right-of-use assets and lease liabilities and income taxes. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. 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 could materially differ from those estimates. Changes in estimates are recorded in the period in which they become known.
COVID-19 Pandemic	COVID-19 Pandemic With the global spread of the ongoing COVID-19 pandemic, including variants of COVID-19, the Company established a cross-functional task force and has implemented business continuity plans designed to address and mitigate the impact of the COVID-19 pandemic on its employees and its business, including its preclinical studies and its ongoing and planned clinical trials. The Company has taken measures to secure its research and development activities, while work in its laboratories and facilities has been re-organized to reduce risk of COVID-19 transmission. While the Company is experiencing limited financial impacts at this time, given the global economic slowdown, the overall disruption of global healthcare systems and the other risks and uncertainties associated with the pandemic, the Company’s business, financial condition, and results of operations could be materially adversely affected. The Company cannot predict the ultimate impact, if any, of COVID-19 related to both known and unknown risks, including future quarantines, closures and other restrictions resulting from the outbreak. The Company continues to closely monitor the COVID-19 pandemic as it evolves its business continuity plans, clinical development plans and response strategy. As of the date of these financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. Actual results could differ from these estimates, and any such differences may be material to the Company’s consolidated financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Financial Assets Measured at Fair Value on a Recurring Basis	The following table presents information about the Company’s financial assets measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values as of September 30, 2021 and December 31, 2020: Description Financial Assets Quoted Significant Significant (in thousands) As at September 30, 2021 Assets Cash equivalents Money market funds $ 2,774 $ 2,774 $ — $ — Marketable securities U.S. Treasury notes 7,194 7,194 — — Total financial assets $ 9,968 $ 9,968 $ — $ — As at December 31, 2020 Assets Cash equivalents Money market funds $ 2,455 $ 2,455 $ — $ — Marketable securities U.S. Treasury notes 7,526 7,526 — — Total financial assets $ 9,981 $ 9,981 $ — $ —

Cash and Cash Equivalents and_2

Cash and Cash Equivalents and Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2021
Investments Debt And Equity Securities [Abstract]
Summary of Cash and Cash Equivalents and Marketable Securities	As of September 30, 2021 and December 31, 2020, cash and cash equivalents and marketable securities were comprised of the following: Amortized Cost Unrealized Gains Unrealized Losses Fair Value (in thousands) As at September 30, 2021 Money market funds included in cash and $ 2,774 $ — $ — $ 2,774 Marketable securities: U.S. Treasury notes 7,194 — — 7,194 Total $ 9,968 $ — $ — $ 9,968 As at December 31, 2020 Money market funds included in cash and $ 2,455 $ — $ — $ 2,455 Marketable securities: U.S. Treasury notes 7,526 — — 7,526 Total $ 9,981 $ — $ — $ 9,981

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2021
Payables And Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities as of September 30, 2021 and December 31, 2020 consisted of the following: September 30, December 31, (in thousands) Accrued compensation and benefits $ 3,361 $ 2,771 Accrued research and development expense 6,808 2,584 Accrued professional services 456 436 Other 395 184 Total accrued expenses and other current liabilities $ 11,020 $ 5,975

Collaboration and License Agr_2

Collaboration and License Agreement (Tables)	9 Months Ended
	Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Transaction Price Performance Obligations	Based on the relative stand-alone selling price, the allocation of the transaction price to the separate performance obligations was as follows: Performance obligation Transaction price (in thousands) Research services $ 6,405 Options to license druggable target lesions 31,148 Options to license undruggable targets 12,447 Total transaction price $ 50,000

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Summary of Lease Costs	The following table contains a summary of the lease costs recognized under ASC 842 and other information pertaining to the Company’s operating leases for the three and nine months ended September 30, 2021 and 2020: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (in thousands) Operating Leases Lease Costs Operating lease costs $ 563 $ 249 $ 1,406 $ 579 Short-term lease costs 22 34 27 38 Variable lease costs 20 16 130 108 Total lease costs $ 605 $ 299 $ 1,563 $ 725
Summary of Other Operating Lease Information	Nine Months Ended September 30, 2021 2020 (in thousands, except as specified otherwise) Other Operating Lease Information Operating cash flows used for operating leases $ 913 $ 513 Right-of-use assets obtained in exchange for new operating lease liability $ 3,827 $ 4,516 Weighted-average remaining lease term (in years) 3.51 4.37 Weighted-average discount rate 4.0 % 5.2 %

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Outstanding Stock Options	Total outstanding stock options as of September 30, 2021 and 2020 were as follows: 2021 2020 Number of Weighted Number of Weighted Outstanding at beginning of period 4,132,123 $ 6.39 3,505,119 $ 2.07 Granted 1,426,616 $ 35.73 899,274 $ 16.61 Exercised ( 217,772 ) $ 3.28 ( 278,246 ) $ 1.83 Cancelled or forfeited ( 84,614 ) $ 26.95 ( 34,637 ) $ 1.96 Outstanding at end of period 5,256,353 $ 14.15 4,091,510 $ 5.28
Schedule of Share-based Compensation Expense	Share-based compensation expense was allocated as follows: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (in thousands) Research and development $ 1,512 $ 269 $ 3,865 $ 565 General and administrative $ 2,124 602 4,919 966 Total share-based compensation expense $ 3,636 $ 871 $ 8,784 $ 1,531
Schedule of Fair Value of Stock Options Determined on Grant Date Using Black Scholes Option-Pricing Model	The fair value of stock options, and the assumptions used in the Black Scholes option-pricing model to determine the grant date fair value of stock options granted to employees and non-employees were as follows, presented on a weighted average basis: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Fair value of stock options $ 21.99 $ 14.42 $ 23.29 $ 10.43 Risk-free interest rate 0.98 % 0.43 % 0.73 % 0.43 % Expected terms (in years) 5.85 6.07 5.99 6.07 Expected volatility 76.10 % 71.30 % 75.61 % 71.99 % Expected dividend yield 0.00 % 0.00 % 0.00 % 0.00 %

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Summary of Computation of Basic and Diluted Net Loss Per Share Attributable To Common Shareholders	The following table summarizes the computation of basic and diluted net loss per share attributable to common shareholders of the Company: Three Months Ended Nine Months Ended 2021 2020 2021 2020 (in thousands, except share and per share amounts) Numerator: Net loss attributable to common shareholders $ ( 30,892 ) $ ( 13,751 ) $ ( 78,618 ) $ ( 38,154 ) Net loss attributable to common shareholders—basic and diluted $ ( 30,892 ) $ ( 13,751 ) $ ( 78,618 ) $ ( 38,154 ) Denominator: Weighted-average number of common shares outstanding—basic 37,122,668 36,756,694 37,026,116 14,486,896 Net loss per share attributable to common shareholders—basic $ ( 0.83 ) $ ( 0.37 ) $ ( 2.12 ) $ ( 2.63 )
Computation of Diluted Net Loss Per Share in Attributable to Common Shareholders Indicate to Anti Diluted Effect	The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common shareholders for the periods indicated because including them would have had an anti-dilutive effect: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Options to purchase common shares 5,256,353 4,091,510 5,256,353 4,091,510

Organization and Nature of Bu_2

Organization and Nature of Business - Additional Information (Details) - USD ($) $ in Thousands	Jun. 23, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Organization and Nature of Business [Line Items]
Entity incorporation, date of incorporation				Sep. 6, 2016
Net proceeds from IPO					$ 232,043
Common Shares
Organization and Nature of Business [Line Items]
Shares issued		3,299
Gross proceeds from IPO	$ 253,000
Net proceeds from IPO	$ 232,000
Convertible preferred shares converted into common shares	21,558,393
Shares issued upon exercise of warrants outstanding	750,000
Common Shares | Initial Public Offering
Organization and Nature of Business [Line Items]
Shares issued	12,650,000		12,650,000
Common Shares | Exercise of Underwriters Option
Organization and Nature of Business [Line Items]
Shares issued	1,650,000

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets Measured at Fair Value on a Recurring Basis (Details) - Fair Value Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets
Total financial assets	$ 9,968	$ 9,981
Money Market Funds
Assets
Total financial assets	2,774	2,455
U.S. Treasury Notes
Assets
Total financial assets	7,194	7,526
Quoted Prices in Active Markets for identical Assets (Level 1)
Assets
Total financial assets	9,968	9,981
Quoted Prices in Active Markets for identical Assets (Level 1) | Money Market Funds
Assets
Total financial assets	2,774	2,455
Quoted Prices in Active Markets for identical Assets (Level 1) | U.S. Treasury Notes
Assets
Total financial assets	$ 7,194	$ 7,526

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details)	Sep. 30, 2021USD ($)
Fair Value Disclosures [Abstract]
Fair value, assets, transfers between levels	$ 0

Cash and Cash Equivalents and_3

Cash and Cash Equivalents and Marketable Securities - Summary of Cash and Cash Equivalents and Marketable Securities (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 9,968,000	$ 9,981,000
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	9,968,000	9,981,000
Money Market Funds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	2,774,000	2,455,000
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	2,774,000	2,455,000
U.S. Treasury Notes
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	7,194,000	7,526,000
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	$ 7,194,000	$ 7,526,000

Cash and Cash Equivalents and_4

Cash and Cash Equivalents and Marketable Securities - Additional Information (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Unrealized gains	$ 0	$ 0
Unrealized losses	$ 0	$ 0

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued compensation and benefits	$ 3,361	$ 2,771
Accrued research and development expense	6,808	2,584
Accrued professional services	456	436
Other	395	184
Total accrued expenses and other current liabilities	$ 11,020	$ 5,975

Collaboration and License Agr_3

Collaboration and License Agreement - Additional Information (Details) - Bristol-Myers Squibb Company - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	May 31, 2021	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	May 31, 2020
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-refundable upfront payment received			$ 50,000		$ 50,000
Options to License Druggable Target Lesions
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-refundable upfront payment received			31,148		31,148
Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration term expiration period	42 months
Initial nonrefundable upfront fee received		$ 50,000
Non-refundable upfront payment received									$ 50,000
Deferred revenue recognized			300	$ 0	700	$ 0
Deferred revenue			49,100		49,100			$ 49,900
Deferred revenue, current			8,900		8,900			2,100
Deferred revenue, noncurrent			$ 40,200		$ 40,200			$ 47,800
Collaboration and License Agreement | Options to License Druggable Target Lesions | Scenario Forecast
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments entitled to be received							$ 6,500
Collaboration and License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments entitled to be received									301,000
Collaboration and License Agreement | Maximum | Research, Development and Regulatory Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments entitled to be received									176,000
Collaboration and License Agreement | Maximum | Commercial Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments entitled to be received									$ 125,000

Collaboration and License Agr_4

Collaboration and License Agreement - Schedule of Transaction Price Performance Obligations (Details) - Bristol-Myers Squibb Company $ in Thousands	Sep. 30, 2021USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price	$ 50,000
Research Activities
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price	6,405
Options to License Druggable Target Lesions
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price	31,148
Options to License Undruggable Targets
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price	$ 12,447

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	1 Months Ended				9 Months Ended
	Aug. 31, 2021USD ($)	Jul. 31, 2021USD ($)	Jun. 30, 2021USD ($)	May 31, 2021USD ($)	Sep. 30, 2021USD ($)Lease	Sep. 30, 2020USD ($)
Lessee Lease Description [Line Items]
Number of operating leases | Lease					5
Lessee, operating lease, existence of option to terminate					false
Operating minimum lease payments					$ 913	$ 513
Office Space | Cambridge, Massachusetts
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend	false			true
Operating lease, option to extend, description	extend the lease term until December 2021			extend the lease term until October 2021
Operating minimum lease payments	$ 100			$ 200
Operating lease, remaining extended lease term	2 months			5 months
Office Space | Cambridge, Massachusetts | New Lease Agreement
Lessee Lease Description [Line Items]
Operating minimum lease payments		$ 3,200
Operating lease, remaining extended lease term		3 years
Office and Laboratory Space | Montreal, Quebec
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend			false
Operating lease, option to extend, description			extend the lease term until July 2025
Operating minimum lease payments		$ 1,100	$ 500
Operating lease, remaining extended lease term			4 years
Operating lease, lease not yet commenced, description		As of September 30, 2021, the amended agreement has not commenced, and is expected to result in $1.1 million of minimum lease payments over the remaining lease term

Leases - Summary of Lease Costs

Leases - Summary of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Lease Costs
Operating lease costs	$ 563	$ 249	$ 1,406	$ 579
Short-term lease costs	22	34	27	38
Variable lease costs	20	16	130	108
Total lease costs	$ 605	$ 299	$ 1,563	$ 725

Leases - Summary of Other Opera

Leases - Summary of Other Operating Lease Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Operating cash flows used for operating leases	$ 913	$ 513
Right-of-use asset obtained in exchange for new operating lease liability	$ 3,827	$ 4,516
Weighted-average remaining lease term (in years)	3 years 6 months 3 days	4 years 4 months 13 days
Weighted-average discount rate	4.00%	5.20%

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended						6 Months Ended	9 Months Ended
	Jun. 30, 2020	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares issued		37,133,938							37,133,938		36,902,924
Number of options exercised									217,772	278,246
Options, weighted-average exercise price									$ 3.28	$ 1.83
Aggregate proceeds from exercise of options									$ 712,000	$ 510,000
Decrease in additional paid-in capital as exercised options credited to common shares									400,000
Unrecognized share-based compensation expense related to unvested stock options		$ 36,500,000							$ 36,500,000
Unrecognized share-based compensation expense related to unvested stock options, weighted average period									2 years 2 months 12 days
Common Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of options exercised		14,489	115,497	87,786	11,559	85,369	181,318
2020 Employee Share Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock reserved for future issuance		686,086							686,086
Annual increases in number of shares available for issuance as percentage of outstanding shares common stock on final day of preceding calendar year	1.00%
Annual increases in number of shares available for issuance maximum number of common stock issued	3,300,000
Purchase price of shares as percentage of fair market value of common stock on date of purchase	85.00%
Common stock shares issued	0	9,943				0			9,943
Share-based compensation expense		$ 100,000			$ 0				$ 100,000	$ 0
2020 Employee Share Purchase Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock reserved for future issuance	327,000					327,000
Option Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock reserved for future issuance	298,605					298,605
Option Plan | Common Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized to be issued		4,074,135							4,074,135
2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock reserved for future issuance		5,797,188							5,797,188
Annual increases in number of shares available for issuance as percentage of outstanding shares common stock on final day of preceding calendar year								5.00%
2020 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock reserved for future issuance	3,807,448					3,807,448
Shares of common stock initially reserved for future issuance	3,600,000					3,600,000

Share-Based Compensation - Sche

Share-Based Compensation - Schedule of Outstanding Stock Options (Details) - $ / shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of shares, Outstanding at beginning of period	4,132,123	3,505,119
Number of shares, Granted	1,426,616	899,274
Number of shares, Exercised	(217,772)	(278,246)
Number of shares, Cancelled or forfeited	(84,614)	(34,637)
Number of shares, Outstanding at end of period	5,256,353	4,091,510
Weighted average exercise price, Outstanding at beginning of period	$ 6.39	$ 2.07
Weighted average exercise price, Granted	35.73	16.61
Weighted average exercise price, Exercised	3.28	1.83
Weighted average exercise price, Cancelled or forfeited	26.95	1.96
Weighted average exercise price, Outstanding at end of period	$ 14.15	$ 5.28

Share-Based Compensation - Sc_2

Share-Based Compensation - Schedule of Share-based Compensation Expense (Details) - Stock Options - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 3,636	$ 871	$ 8,784	$ 1,531
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	1,512	269	3,865	565
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 2,124	$ 602	$ 4,919	$ 966

Share-Based Compensation - Sc_3

Share-Based Compensation - Schedule of Fair Value of Stock Options Determined on Grant Date Using Black Scholes Option-Pricing Model (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Fair value of stock options	$ 21.99	$ 14.42	$ 23.29	$ 10.43
Risk-free interest rate	0.98%	0.43%	0.73%	0.43%
Expected terms (in years)	5 years 10 months 6 days	6 years 25 days	5 years 11 months 26 days	6 years 25 days
Expected volatility	76.10%	71.30%	75.61%	71.99%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Net Loss per Share - Summary of

Net Loss per Share - Summary of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss attributable to common shareholders	$ (30,892)	$ (13,751)	$ (78,618)	$ (38,154)
Net loss attributable to common shareholders—basic and diluted	$ (30,892)	$ (13,751)	$ (78,618)	$ (38,154)
Denominator:
Weighted-average common shares outstanding—basic and diluted	37,122,668	36,756,694	37,026,116	14,486,896
Net loss per share attributable to common shareholders—basic and diluted	$ (0.83)	$ (0.37)	$ (2.12)	$ (2.63)

Net Loss per Share - Computatio

Net Loss per Share - Computation of Diluted Net Loss Per Share in Attributable to Common Shareholders Indicate to Anti Diluted Effect (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Options to Purchase Common Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	5,256,353	4,091,510	5,256,353	4,091,510

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) $ / shares in Units, ¥ in Millions, $ in Millions	Nov. 01, 2021USD ($)$ / sharesshares	Oct. 29, 2021	Jun. 23, 2020shares	Jun. 30, 2021shares	Oct. 13, 2021USD ($)	Oct. 13, 2021JPY (¥)
Common Shares
Subsequent Event [Line Items]
Shares issued				3,299
Follow-on Offering | Subsequent Events
Subsequent Event [Line Items]
Underwriting commissions and estimated offering expenses | $	$ 1.2
Follow-on Offering | Common Shares | Subsequent Events
Subsequent Event [Line Items]
Shares issued	4,600,000
Shares issued, price per share | $ / shares	$ 22
Net proceeds from issuance of common shares | $	$ 93.9
Exercise of Underwriters Option | Common Shares
Subsequent Event [Line Items]
Shares issued			1,650,000
Exercise of Underwriters Option | Common Shares | Maximum | Subsequent Events
Subsequent Event [Line Items]
Shares issued	600,000
Collaboration and License Agreement | Ono Pharmaceutical Co., Ltd. | Subsequent Events
Subsequent Event [Line Items]
Research service payments entitled to be received					$ 0.9	¥ 100
Collaboration term extended period		1 year