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Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2020	Aug. 13, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Trading Symbol	RPTX
Entity Registrant Name	Repare Therapeutics Inc.
Entity Central Index Key	0001808158
Entity Current Reporting Status	No
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		36,753,454
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 Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash	$ 369,933	$ 94,797
Research and development tax credits receivable	1,414	1,080
Other receivables	2,621	1,976
Prepaid expenses and other current assets	3,296	719
Total current assets	377,264	98,572
Property and equipment, net	2,453	2,390
Restricted cash	199	208
Operating lease right-of-use assets	729	1,034
Other assets	894	359
Deferred tax assets	192	132
TOTAL ASSETS	381,731	102,695
CURRENT LIABILITIES:
Accounts payable	3,576	2,127
Accrued expenses and other current liabilities	5,262	1,276
Operating lease liability, current portion	608	625
Income tax payable	351	218
Total current liabilities	9,797	4,246
Operating lease liability, net of current portion	136	439
Deferred revenue	58,142	8,142
TOTAL LIABILITIES	68,075	12,827
TOTAL CONVERTIBLE PREFERRED SHARES		135,997
SHAREHOLDERS’ EQUITY (DEFICIT)
Preferred shares, no par value per share; unlimited shares and 0 shares authorized as of June 30, 2020 and December 31, 2019, respectively; 0 shares issued and outstanding as of June 30, 2020 and December 31, 2019
Common shares, no par value per share; unlimited shares authorized as of June 30, 2020 and December 31, 2019; 36,753,454 and 1,528,374 shares issued and outstanding as of June 30, 2020, and December 31, 2019, respectively	383,818	1
Additional paid-in capital	4,182	3,811
Accumulated deficit	(74,344)	(49,941)
Total shareholders’ equity (deficit)	313,656	(46,129)
TOTAL LIABILITIES, CONVERTIBLE PREFERRED SHARES AND SHAREHOLDERS’ EQUITY (DEFICIT)	$ 381,731	102,695
Series A Convertible Preferred Shares
CURRENT LIABILITIES:
TOTAL CONVERTIBLE PREFERRED SHARES		53,749
Series B Convertible Preferred Shares
CURRENT LIABILITIES:
TOTAL CONVERTIBLE PREFERRED SHARES		$ 82,248

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Common stock par value
Common stock shares authorized	Unlimited	Unlimited
Common stock shares issued	36,753,454	1,528,374
Common stock shares outstanding	36,753,454	1,528,374
Preferred stock par value
Preferred stock shares authorized	Unlimited
Preferred stock shares authorized		0
Preferred stock shares issued	0	0
Preferred stock shares outstanding	0	0
Series A Convertible Preferred Shares
Temporary equity par value	$ 0	$ 0
Temporary equity shares authorized	0
Temporary equity shares authorized		Unlimited
Temporary equity shares issued	0	11,090,135
Temporary equity shares outstanding	0	11,090,135
Temporary equity, liquidation and redemption value	$ 0	$ 52,750
Series B Convertible Preferred Shares
Temporary equity par value	$ 0	$ 0
Temporary equity shares authorized	0
Temporary equity shares authorized		Unlimited
Temporary equity shares issued	0	10,468,258
Temporary equity shares outstanding	0	10,468,258
Temporary equity, liquidation and redemption value	$ 0	$ 82,496

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating expenses:
Research and development, net of tax credits	$ 8,951	$ 4,853	$ 17,583	$ 8,556
General and administrative	3,372	1,032	5,555	2,108
Total operating expenses	12,323	5,885	23,138	10,664
Loss from operations	(12,323)	(5,885)	(23,138)	(10,664)
Other income (expense), net
Realized and unrealized gain (loss) on foreign exchange	595	227	(1,136)	299
Change in fair value of Series A preferred share tranche obligation		(680)		(700)
Other expense	(4)	(1)	(6)	(3)
Total other income (expense), net	591	(454)	(1,142)	(404)
Loss before income taxes	(11,732)	(6,339)	(24,280)	(11,068)
Income tax expense	(70)	(20)	(123)	(129)
Net loss and comprehensive loss	(11,802)	(6,359)	(24,403)	(11,197)
Net loss attributable to common shareholders—basic and diluted	$ (11,802)	$ (6,359)	$ (24,403)	$ (11,197)
Net loss per share attributable to common shareholders—basic and diluted	$ (2.45)	$ (4.16)	$ (7.56)	$ (7.33)
Weighted-average common shares outstanding—basic and diluted	4,825,214	1,528,374	3,229,635	1,528,374

Condensed Consolidated Statements of Convertible Preferred Shares and Shareholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Initial Public Offering	Series A Convertible Preferred Shares	Series B Convertible Preferred Shares	Common Shares	Common Shares Initial Public Offering	Additional Paid-in Capital	Accumulated Deficit
Balance at Dec. 31, 2018	$ (22,384)				$ 1		$ 340	$ (22,725)
Temporary equity balance, Shares at Dec. 31, 2018			6,813,340
Temporary equity balance, Value at Dec. 31, 2018			$ 31,873
Balance, Shares at Dec. 31, 2018					1,528,374
Issuance of Series A convertible preferred shares, net of issuance costs			$ 21,876
Issuance of Series A convertible preferred shares, net of issuance costs, Shares			4,276,795
Share-based compensation expense	65						65
Net loss and comprehensive loss	(4,838)							(4,838)
Balance at Mar. 31, 2019	(27,157)				$ 1		405	(27,563)
Temporary equity balance, Shares at Mar. 31, 2019			11,090,135
Temporary equity balance, Value at Mar. 31, 2019			$ 53,749
Balance, Shares at Mar. 31, 2019					1,528,374
Balance at Dec. 31, 2018	(22,384)				$ 1		340	(22,725)
Temporary equity balance, Shares at Dec. 31, 2018			6,813,340
Temporary equity balance, Value at Dec. 31, 2018			$ 31,873
Balance, Shares at Dec. 31, 2018					1,528,374
Net loss and comprehensive loss	(11,197)
Balance at Jun. 30, 2019	(33,395)				$ 1		526	(33,922)
Temporary equity balance, Shares at Jun. 30, 2019			11,090,135
Temporary equity balance, Value at Jun. 30, 2019			$ 53,749
Balance, Shares at Jun. 30, 2019					1,528,374
Balance at Mar. 31, 2019	(27,157)				$ 1		405	(27,563)
Temporary equity balance, Shares at Mar. 31, 2019			11,090,135
Temporary equity balance, Value at Mar. 31, 2019			$ 53,749
Balance, Shares at Mar. 31, 2019					1,528,374
Share-based compensation expense	121						121
Net loss and comprehensive loss	(6,359)							(6,359)
Balance at Jun. 30, 2019	(33,395)				$ 1		526	(33,922)
Temporary equity balance, Shares at Jun. 30, 2019			11,090,135
Temporary equity balance, Value at Jun. 30, 2019			$ 53,749
Balance, Shares at Jun. 30, 2019					1,528,374
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	135,997		$ 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	$ 135,997		$ 53,749	$ 82,248
Balance, Shares at Dec. 31, 2019					1,528,374
Exercise of stock options, Shares	266,687
Issuance of warrant and conversion into common shares,Value	$ 15,000
Net loss and comprehensive loss	(24,403)
Balance at Jun. 30, 2020	313,656				$ 383,818		4,182	(74,344)
Temporary equity balance, Shares at Jun. 30, 2020			0	0
Balance, Shares at Jun. 30, 2020					36,753,454
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 upon initial public offering, net of issuance costs		$ 232,043				$ 232,043
Issuance of common shares upon initial public offering, 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)
Temporary equity balance, Shares at Jun. 30, 2020			0	0
Balance, Shares at Jun. 30, 2020					36,753,454

Condensed Consolidated Statements of Convertible Preferred Shares and Shareholders' Equity (Deficit) (Parenthetical) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Mar. 31, 2019
Initial Public Offering
Stock issuance costs	$ 20,957
Series A Convertible Preferred Shares
Stock issuance costs		$ 5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash Flows From Operating Activities:
Net loss and comprehensive loss for the period	$ (24,403)	$ (11,197)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Share-based compensation expense	660	186
Depreciation expense	403	262
Change in fair value of the Series A preferred shares tranche obligation		700
Non-cash lease expense	305	86
Foreign exchange loss (gain)	1,162	(522)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(2,577)	(155)
Research and development tax credits receivable	(381)	(246)
Other receivables	(725)	(566)
Deferred tax asset	(60)	(42)
Other non-current assets	(535)	(15)
Accounts payable	915	260
Accrued expenses and other current liabilities	2,371	(119)
Operating lease liability, current portion	(9)	15
Income tax payable	133	72
Operating lease liability, net of current portion	(292)	(93)
Deferred revenue	50,000	8,142
Net cash provided by (used in) operating activities	26,967	(3,232)
Cash Flows From Investing Activities:
Purchase of property and equipment	(43)	(380)
Net cash used in investing activities	(43)	(380)
Cash Flows From Financing Activities:
Proceeds from issuance of Series A preferred shares, net		20,995
Proceeds from exercise of stock options	488
Proceeds from issuance of warrant	15,000
Net proceeds from issuance of common shares in initial public offering	233,760
Net cash provided by financing activities	249,248	20,995
Effect of exchange rate fluctuations on cash held	(1,045)	482
Net Increase In Cash And Restricted Cash	275,127	17,865
Cash and restricted cash at beginning of period	95,005	10,929
Cash and restricted cash at end of period	370,132	28,794
Reconciliation Of Cash And Restricted Cash
Cash	369,933	28,588
Restricted cash	199	206
Total cash and restricted cash	370,132	28,794
Supplemental Disclosure Of Cash Flow Information:
Property and equipment purchases in accounts payable	423	$ 14
Initial public offering costs in accounts payable	102
Initial public offering costs in accruals and other current liabilities	1,615
Conversion of Series A and B convertible preferred shares into common shares	135,997
Conversion of warrant into common shares	$ 15,000

Organization and Nature of Business

6 Months Ended

Jun. 30, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Nature of Business

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 following the completion of its initial public offering (the “IPO”), the Company was continued as a corporation under the Business Corporations Act (Québec).

On June 12, 2020, the Company effected a 1-for-6.062 reverse stock split of the Company’s share capital. Accordingly, all common shares, Series A and B preferred shares, stock options and per share amounts in these unaudited condensed consolidated financial statements have been retroactively adjusted to reflect the reverse stock split on a retroactive basis for all periods presented.

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 $253,000. The Company’s shares began trading on the Nasdaq Global Select Market under the ticker symbol “RPTX” on June 19, 2020. The Company received $232,043 in net proceeds after deducting underwriting discounts and 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 Accounting Policies

6 Months Ended

Jun. 30, 2020

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, 2019, 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 June 30, 2020, the consolidated results of its operations for the three and six months ended June 30, 2020 and 2019, its statements of shareholders’ equity for the three and six months ended June 30, 2020 and 2019 and its consolidated cash flows for the six months ended June 30, 2020 and 2019.

The accompanying 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, 2019 included in the Company’s final prospectus that forms part of the Company’s Registration Statement on Form S-1 (File No. 333-238822), filed with the Securities and Exchange Commission (the “SEC”) pursuant to Rule 424(b)(4) on June 19, 2020 (the “Prospectus”). The condensed consolidated balance sheet data as of December 31, 2019 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 six months ended June 30, 2020 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, 2019 included in the Prospectus. Since the date of the audited consolidated financial statements for the year ended December 31, 2019 included in the Prospectus, there have been no changes to its significant accounting policies.

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 consolidated financial statements include, but are not limited to, accrued research and development expenses and share-based compensation. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates.

COVID-19 Pandemic

With the global spread of the ongoing COVID-19 pandemic in the first half of 2020, 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’s operations are considered as an “essential business” and therefore, the Company is continuing to operate during this period. 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 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 these estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. Actual results could differ from those estimates, and any such differences may be material to the Company’s financial statements.

Accrued Expenses and Other Current Liabilities

6 Months Ended

Jun. 30, 2020

Payables And Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

3. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities as of June 30, 2020 and December 31, 2019 consisted of the following:

	June 30, 2020		December 31, 2019
Accrued compensation and benefits	$	1,118	$	1,043
Accrued research and development expense		1,814		208
Accrued initial public offering costs		1,615		—
Accrued professional services		668		21
Other		47		4
Total accrued expenses and other current liabilities	$	5,262	$	1,276

Collaboration and License Agreement

6 Months Ended

Jun. 30, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Collaboration and License Agreement

4. 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 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. The collaboration consists of programs directed to both druggable targets and to targets commonly considered undruggable to traditional small molecule approaches. In the event that Bristol Myers Squibb elects to obtain an exclusive license for the subsequent development, manufacturing and commercialization of a program, Bristol Myers Squibb will then be solely responsible for all such worldwide activities.

Under the terms of the agreement, Bristol Myers Squibb paid the Company an initial nonrefundable upfront fee payment of $50,000 in June 2020. The Company is entitled to receive up to $301,000 in total milestones on a program-by-program basis, consisting of $176,000 in the aggregate for certain specified research, development and regulatory milestones and $125,000 in the aggregate for certain specified commercial milestones. The Company is also 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 collaboration and license 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 agreement, including research services for each campaign, as well as 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 upfront payment received of $50,000. Additional consideration to be paid to the Company upon the exercise of the license options and future milestone payments were excluded from the transaction price as they represent option fees and milestone payments that can only be achieved subsequent to option exercises and the achievement of the milestone events.

The Company will allocate the transaction price to each performance obligation based on the relative stand-alone selling price of each performance obligation at inception. Revenue is expected to be recognized at the point in time when option licenses are exercised by Bristol Myers Squibb, with the remainder to be recognized on a proportional performance basis over the period of service for research services. The upfront payment of $50,000 has been recorded as deferred revenue as of June 30, 2020 as, up to that point in time, no research and development services had been performed under the agreement and no options were exercised.

In conjunction with the collaboration and license agreement, the Company entered into a warrant agreement with an affiliate of Bristol Myers Squibb pursuant to which the Company issued a warrant for total proceeds of $15,000. Upon closing of the IPO, this warrant was automatically exercised into 750,000 common shares of the Company. The Company evaluated whether the warrant should be treated as a separate agreement or a single arrangement with the collaboration and license agreement. Although both agreements were negotiated concurrently, the warrant was issued at fair value. Accordingly, the Company accounted for the warrant agreement separately from the collaboration and license agreement.

Leases

6 Months Ended

Jun. 30, 2020

Leases [Abstract]

Leases

5. Leases

The Company has historically entered into lease arrangements for its facilities. As of June 30, 2020, the Company had three operating leases with required future minimum payments. The Company’s leases generally do not include termination or purchase options.

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 six months ended June 30, 2020:

	Three Months Ended		Six Months Ended
	June 30, 2020		June 30, 2020
Operating Leases
Lease Cost
Operating lease cost	$	165	$	330
Short-term lease cost		1		4
Variable lease cost		39		92
Total lease cost	$	205	$	426

	June 30, 2020
Other Operating Lease Information
Operating cash flows used for operating leases	$	335
Weighted-average remaining lease term	1.37 years
Weighted-average discount rate		7.6	%

Shareholders' Deficit

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

Shareholders' Deficit

6. Shareholders’ Deficit

Convertible Preferred Shares

The Company’s Series A and Series B convertible preferred shares were convertible on a one-to-one basis into common shares. Upon completion of the IPO, all issued and outstanding Series A and Series B convertible preferred shares were converted into 21,558,393 common shares and the existing classes of Series A and Series B convertible preferred shares were removed (unlimited preferred shares authorized, 11,090,135 Series A convertible preferred shares and 10,468,258 Series B convertible preferred shares issued and outstanding as of December 31, 2019).

Effective upon the closing of the IPO, the Company authorized for issue an unlimited number of preferred shares, issuable in series. No preferred shares were issued and outstanding as of June 30, 2020.

Warrant

In conjunction with the collaboration and license agreement with Bristol Myers Squibb, the Company entered into a warrant agreement with an affiliate of Bristol Myers Squibb pursuant to which the Company issued a warrant for total proceeds of $15,000 on May 26, 2020. Upon closing of the IPO, the warrant was automatically exercised at the public offering price of $20.00 per share into 750,000 common shares of the Company.

Common Shares

Authorized share capital

An unlimited number of common shares, voting and participating, without par value.

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, at the public offering price of $20.00 per share, for aggregate gross proceeds of $253,000. The Company received $232,043 in net proceeds after deducting underwriting discounts and 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 automatically converted into 750,000 common shares.

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 is 327,000. Additionally, the number of shares reserved and available for issuance under the ESPP will automatically increase 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. 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. The ESPP will become active upon approval of the plan administrator, which is the Company’s board of directors. As of June 30, 2020, no common shares have been issued under the ESPP.

Share-Based Compensation

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 making awards under the Option Plan. The 2020 Plan allows the Company’s compensation committee to make 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) (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 will automatically increase each January 1, beginning on January 1, 2021 and each January 1 thereafter through January 31, 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.

The 2020 Plan is administered by the Company’s board of directors. The exercise prices, vesting and other restrictions are determined by the board of directors, except that the exercise price per share may not be less than 100% of the fair value of the common share on the date of grant, determined based on the average of the daily volume-weighted average trading price of shares on each of the five trading days immediately preceding the date of grant. Stock option awards under the 2020 Plan expire 10 years after the grant date and generally have vesting conditions of 25% on the first anniversary date of the grant and 75% on a monthly basis at a rate of 1/36^th unless otherwise decided by the board of directors.

Total outstanding stock options as of June 30, 2020 and 2019 were as follows:

	2020					2019
	Number of shares			Weighted average exercise price		Number of shares		Weighted average exercise price
Outstanding at beginning of period		3,505,119		$	2.07		907,315	$	1.66
Granted		869,075		$	16.35		1,013,635	$	2.06
Exercised		(266,687	)	$	1.83		—		—
Cancelled or forfeited		(7,962	)	$	2.13		—		—
Outstanding at end of period		4,099,545		$	5.11		1,920,950	$	1.87

During the six months ended June 30, 2020, an aggregate of 266,687 options were exercised at a weighted-average exercise price of $1.83 per share, for aggregate proceeds of $488. As a result, an amount of $289 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 June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Research and development	$	163	$	63	$	296	$	103
General and administrative		226		58		364		83
Total share-based compensation expense	$	389	$	121	$	660	$	186

The assumptions that the Company 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 June 30,					Six Months Ended June 30,
	2020			2019		2020			2019
Fair value of stock options	$	10.30			—	$	10.30		$	0.97
Exercise price	$	16.35			—	$	16.35		$	2.06
Share price	$	16.35			—	$	16.35		$	2.06
Risk-free interest rate		0.43	%		—		0.43	%		2.27	%
Expected terms (in years)		6.07			—		6.07			6.08
Expected volatility		71.99	%		—		71.99	%		70.79	%
Expected dividend yield		0.00	%		—		0.00	%		0.00	%

As of June 30, 2020, there was $11,837 of unrecognized share-based compensation expense related to unvested stock options to be recognized over a period of 3.0 years.

Net Loss per Share

6 Months Ended

Jun. 30, 2020

Earnings Per Share [Abstract]

Net Loss per Share

7. 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 June 30,						Six Months Ended June 30,
	2020			2019			2020			2019
	(in thousands, except share and per share amounts)
Numerator:
Net loss attributable to common shareholders	$	(11,802	)	$	(6,359	)	$	(24,403	)	$	(11,197	)
Net loss attributable to common shareholders—basic and diluted	$	(11,802	)	$	(6,359	)	$	(24,403	)	$	(11,197	)
Denominator:
Weighted-average number of common shares outstanding—basic and diluted		4,825,214			1,528,374			3,229,635			1,528,374
Net loss per share attributable to common shareholders—basic and diluted	$	(2.45	)	$	(4.16	)	$	(7.56	)	$	(7.33	)

The Company’s potentially dilutive securities, which include convertible preferred shares and 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 June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Series A preferred shares		—		11,090,135		—		11,090,135
Series B preferred shares		—		—		—		—
Options to purchase common shares		4,099,545		1,920,950		4,099,545		1,920,950

Significant Agreements and Commitments

6 Months Ended

Jun. 30, 2020

Significant Agreements And Commitments Disclosure [Abstract]

Significant Agreements and Commitments

8. Significant Agreements and Commitments

In March 2020, the Company executed a strategic collaboration with The University of Texas M. D. Anderson Cancer Center (“MDACC”). The collaboration will consist of preclinical studies and clinical trials designed by the Company and MDACC with the research conducted by MDACC. The Company has agreed to commit $10,000 in funding for various studies over a period of five years, of which $2,000 was paid in April 2020.

In June 2020, the Company procured a directors and officers (D&O) liability insurance for a total aggregate premium of $6,420, including excise tax, of which $270 has been recognized as accrued expenses and other current liabilities as of June 30, 2020, with a corresponding increase in general and administrative expenses. The total aggregate premium of D&O insurance in the amount of $6,420 was paid and $6,150 was recorded as prepaid expenses and other current assets in July 2020.

Subsequent Events

6 Months Ended

Jun. 30, 2020

Subsequent Events [Abstract]

Subsequent Events

9. Subsequent Events

In August 2020, the board of directors of the Company authorized the issuance of an aggregate of 30,199 stock options to employees under the 2020 Plan, at a weighted average exercise price of $24.00 per share.

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2020
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, 2019, 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 June 30, 2020, the consolidated results of its operations for the three and six months ended June 30, 2020 and 2019, its statements of shareholders’ equity for the three and six months ended June 30, 2020 and 2019 and its consolidated cash flows for the six months ended June 30, 2020 and 2019. The accompanying 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, 2019 included in the Company’s final prospectus that forms part of the Company’s Registration Statement on Form S-1 (File No. 333-238822), filed with the Securities and Exchange Commission (the “SEC”) pursuant to Rule 424(b)(4) on June 19, 2020 (the “Prospectus”). The condensed consolidated balance sheet data as of December 31, 2019 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 six months ended June 30, 2020 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, 2019 included in the Prospectus. Since the date of the audited consolidated financial statements for the year ended December 31, 2019 included in the Prospectus, there have been no changes to its significant accounting policies.
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 consolidated financial statements include, but are not limited to, accrued research and development expenses and share-based compensation. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates.
COVID-19 Pandemic	COVID-19 Pandemic With the global spread of the ongoing COVID-19 pandemic in the first half of 2020, 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’s operations are considered as an “essential business” and therefore, the Company is continuing to operate during this period. 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 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 these estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. Actual results could differ from those estimates, and any such differences may be material to the Company’s financial statements.

Accrued Expenses and Other Current Liabilities (Tables)

6 Months Ended

Jun. 30, 2020

Payables And Accruals [Abstract]

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities as of June 30, 2020 and December 31, 2019 consisted of the following:

	June 30, 2020		December 31, 2019
Accrued compensation and benefits	$	1,118	$	1,043
Accrued research and development expense		1,814		208
Accrued initial public offering costs		1,615		—
Accrued professional services		668		21
Other		47		4
Total accrued expenses and other current liabilities	$	5,262	$	1,276

Leases (Tables)

6 Months Ended

Jun. 30, 2020

Leases [Abstract]

Summary of Lease Costs

	Three Months Ended		Six Months Ended
	June 30, 2020		June 30, 2020
Operating Leases
Lease Cost
Operating lease cost	$	165	$	330
Short-term lease cost		1		4
Variable lease cost		39		92
Total lease cost	$	205	$	426

Summary of Other Operating Lease Information

	June 30, 2020
Other Operating Lease Information
Operating cash flows used for operating leases	$	335
Weighted-average remaining lease term	1.37 years
Weighted-average discount rate		7.6	%

Shareholders' Deficit (Tables)

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

Schedule of Outstanding Stock Options

Total outstanding stock options as of June 30, 2020 and 2019 were as follows:

	2020					2019
	Number of shares			Weighted average exercise price		Number of shares		Weighted average exercise price
Outstanding at beginning of period		3,505,119		$	2.07		907,315	$	1.66
Granted		869,075		$	16.35		1,013,635	$	2.06
Exercised		(266,687	)	$	1.83		—		—
Cancelled or forfeited		(7,962	)	$	2.13		—		—
Outstanding at end of period		4,099,545		$	5.11		1,920,950	$	1.87

Schedule of Share-based Compensation Expense

Share-based compensation expense was allocated as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Research and development	$	163	$	63	$	296	$	103
General and administrative		226		58		364		83
Total share-based compensation expense	$	389	$	121	$	660	$	186

Schedule of Fair Value of Stock Options Determined on Grant Date Using Black Scholes Option-Pricing Model

	Three Months Ended June 30,					Six Months Ended June 30,
	2020			2019		2020			2019
Fair value of stock options	$	10.30			—	$	10.30		$	0.97
Exercise price	$	16.35			—	$	16.35		$	2.06
Share price	$	16.35			—	$	16.35		$	2.06
Risk-free interest rate		0.43	%		—		0.43	%		2.27	%
Expected terms (in years)		6.07			—		6.07			6.08
Expected volatility		71.99	%		—		71.99	%		70.79	%
Expected dividend yield		0.00	%		—		0.00	%		0.00	%

Net Loss per Share (Tables)

6 Months Ended

Jun. 30, 2020

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 June 30,						Six Months Ended June 30,
	2020			2019			2020			2019
	(in thousands, except share and per share amounts)
Numerator:
Net loss attributable to common shareholders	$	(11,802	)	$	(6,359	)	$	(24,403	)	$	(11,197	)
Net loss attributable to common shareholders—basic and diluted	$	(11,802	)	$	(6,359	)	$	(24,403	)	$	(11,197	)
Denominator:
Weighted-average number of common shares outstanding—basic and diluted		4,825,214			1,528,374			3,229,635			1,528,374
Net loss per share attributable to common shareholders—basic and diluted	$	(2.45	)	$	(4.16	)	$	(7.56	)	$	(7.33	)

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 June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Series A preferred shares		—		11,090,135		—		11,090,135
Series B preferred shares		—		—		—		—
Options to purchase common shares		4,099,545		1,920,950		4,099,545		1,920,950

Organization and Nature of Business - Additional Information (Details) $ in Thousands			3 Months Ended	6 Months Ended
	Jun. 23, 2020 USD ($) shares	Jun. 12, 2020	Jun. 30, 2020 shares	Jun. 30, 2020 USD ($) shares
Organization and Nature of Business [Line Items]
Entity incorporation, date of incorporation				Sep. 06, 2016
Reverse stock split of share capital				1-for-6.062
Conversion ratio		0.16496
Net proceeds from IPO \| $				$ 233,760
Common Shares
Organization and Nature of Business [Line Items]
Gross proceeds from IPO \| $	$ 253,000
Net proceeds from IPO \| $	$ 232,043
Convertible preferred shares converted into common shares	21,558,393			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

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued compensation and benefits	$ 1,118	$ 1,043
Accrued research and development expense	1,814	208
Accrued initial public offering costs	1,615
Accrued professional services	668	21
Other	47	4
Total accrued expenses and other current liabilities	$ 5,262	$ 1,276

Collaboration and License Agreement - Additional Information (Details) - USD ($)		1 Months Ended		6 Months Ended
	May 26, 2020	Jun. 30, 2020	May 31, 2020	Jun. 30, 2020	Jun. 23, 2020
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from issuance of warrant				$ 15,000,000
Common Shares
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Warrants exercised to shares of common stock					750,000
Bristol-Myers Squibb Company \| Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Initial nonrefundable upfront fee payment received		$ 50,000,000
Upfront payment received			$ 50,000,000
Bristol-Myers Squibb Company \| Collaboration and License Agreement \| Deferred Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment received		$ 50,000,000		$ 50,000,000
Bristol-Myers Squibb Company \| Collaboration and License Agreement \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments entitled to be received			301,000,000
Bristol-Myers Squibb Company \| Research, Development and Regulatory Milestones \| Collaboration and License Agreement \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments entitled to be received			176,000,000
Bristol-Myers Squibb Company \| Commercial Milestones \| Collaboration and License Agreement \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments entitled to be received			125,000,000
Affiliate of Bristol Myers Squibb
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Proceeds from issuance of warrant	$ 15,000,000		$ 15,000,000
Affiliate of Bristol Myers Squibb \| Common Shares
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Warrants exercised to shares of common stock					750,000

Leases - Additional Information (Details)	6 Months Ended
Leases - Additional Information (Details)	Jun. 30, 2020 Lease
Leases [Abstract]
Number of operating leases	3
Lessee, operating lease, existence of option to terminate	false

Leases - Summary of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Lease Cost
Operating lease cost	$ 165	$ 330
Short-term lease cost	1	4
Variable lease cost	39	92
Total lease cost	$ 205	$ 426

Leases - Summary of Other Operating Lease Information (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($)
Leases [Abstract]
Operating cash flows used for operating leases	$ 335
Weighted-average remaining lease term	1 year 4 months 13 days
Weighted-average discount rate	7.60%

Shareholders' Deficit - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended		3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 23, 2020	May 26, 2020	Jun. 30, 2020	May 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Proceeds from issuance of warrant							$ 15,000
Net proceeds from issuance of common shares in initial public offering							$ 233,760
Common stock shares issued			36,753,454		36,753,454		36,753,454	1,528,374
Number of options exercised							266,687
Options, weighted-average exercise price							$ 1.83
Aggregate proceeds from exercise of options							$ 488
Decrease in additional paid-in capital as exercised options credited to common shares							289
Unrecognized share-based compensation expense related to unvested stock options			$ 11,837		$ 11,837		$ 11,837
Unrecognized share-based compensation expense related to unvested stock options, recognition period							3 years
2020 Employee Share Purchase Plan
Class Of Stock [Line Items]
Annual increase in number of shares available for issuance as percentage of outstanding shares common stock on final day of preceding calendar year			1.00%
Common stock shares issued			0		0		0
Annual increase 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%
Option Plan
Class Of Stock [Line Items]
Shares of common stock reserved for future issuance			298,605		298,605		298,605
2020 Equity Incentive Plan
Class Of Stock [Line Items]
Annual increase in number of shares available for issuance as percentage of outstanding shares common stock on final day of preceding calendar year			5.00%
Exercise price per share as minimum percentage of fair value of common share	100.00%
Expiration period	10 years
Monthly vesting rate	1/36th
2020 Equity Incentive Plan \| Vesting on First Anniversary Date of Grant
Class Of Stock [Line Items]
Vesting percentage	25.00%
2020 Equity Incentive Plan \| Vesting on Monthly Basis at Rate of 1/36th
Class Of Stock [Line Items]
Vesting percentage	75.00%
Maximum \| 2020 Employee Share Purchase Plan
Class Of Stock [Line Items]
Shares of common stock reserved for future issuance			327,000		327,000		327,000
Maximum \| 2020 Equity Incentive Plan
Class Of Stock [Line Items]
Shares of common stock reserved for future issuance			3,807,448		3,807,448		3,807,448
Shares of common stock initially reserved for future issuance			3,600,000		3,600,000		3,600,000
Affiliate of Bristol Myers Squibb
Class Of Stock [Line Items]
Proceeds from issuance of warrant		$ 15,000		$ 15,000
Affiliate of Bristol Myers Squibb \| Initial Public Offering
Class Of Stock [Line Items]
Warrant exercise price per share	$ 20.00
Series A Convertible Preferred Shares
Class Of Stock [Line Items]
Temporary equity shares authorized								Unlimited
Temporary equity shares issued			0		0		0	11,090,135
Temporary equity shares outstanding			0		0	11,090,135	0	11,090,135	11,090,135	11,090,135	6,813,340
Series B Convertible Preferred Shares
Class Of Stock [Line Items]
Temporary equity shares authorized								Unlimited
Temporary equity shares issued			0		0		0	10,468,258
Temporary equity shares outstanding			0		0	10,468,258	0	10,468,258
Common Shares
Class Of Stock [Line Items]
Preferred shares converted into common shares	21,558,393						21,558,393
Shares issued upon exercise of warrants outstanding	750,000
Shares issued, price per share	$ 20.00
Gross proceeds from IPO	$ 253,000
Net proceeds from issuance of common shares in initial public offering	$ 232,043
Number of options exercised					85,369	181,318
Common Shares \| Option Plan
Class Of Stock [Line Items]
Number of shares authorized to be issued			4,074,135		4,074,135		4,074,135
Common Shares \| Initial Public Offering
Class Of Stock [Line Items]
Issuance of common shares upon initial public offering, Shares	12,650,000				12,650,000
Common Shares \| Exercise of Underwriters Option
Class Of Stock [Line Items]
Issuance of common shares upon initial public offering, Shares	1,650,000
Common Shares \| Exercise of Underwriters Option \| Maximum
Class Of Stock [Line Items]
Issuance of common shares upon initial public offering, Shares	1,650,000
Common Shares \| Affiliate of Bristol Myers Squibb
Class Of Stock [Line Items]
Shares issued upon exercise of warrants outstanding	750,000

Shareholders' Deficit - Schedule of Outstanding Stock Options (Details) - $ / shares	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Equity [Abstract]
Number of shares, Outstanding at beginning of period	3,505,119	907,315
Number of shares, Granted	869,075	1,013,635
Number of shares, Exercised	(266,687)
Number of shares, Cancelled or forfeited	(7,962)
Number of shares, Outstanding at end of period	4,099,545	1,920,950
Weighted average exercise price, Outstanding at beginning of period	$ 2.07	$ 1.66
Weighted average exercise price, Granted	16.35	2.06
Weighted average exercise price, Exercised	1.83
Weighted average exercise price, Cancelled or forfeited	2.13
Weighted average exercise price, Outstanding at end of period	$ 5.11	$ 1.87

Shareholders' Deficit - Schedule of Share-based Compensation Expense (Details) - Stock Options - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 389	$ 121	$ 660	$ 186
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	163	63	296	103
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 226	$ 58	$ 364	$ 83

Shareholders' Deficit - Schedule of Fair Value of Stock Options Determined on Grant Date Using Black Scholes Option-Pricing Model (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Equity [Abstract]
Fair value of stock options	$ 10.30	$ 0.97	$ 10.30	$ 0.97
Exercise price	16.35	2.06	16.35	2.06
Share price	$ 16.35	$ 2.06	$ 16.35	$ 2.06
Risk-free interest rate	0.43%		0.43%	2.27%
Expected terms (in years)	6 years 25 days	0 years	6 years 25 days	6 years 29 days
Expected volatility	71.99%		71.99%	70.79%
Expected dividend yield	0.00%		0.00%	0.00%

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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Net loss attributable to common shareholders—basic and diluted	$ (11,802)	$ (6,359)	$ (24,403)	$ (11,197)
Net loss attributable to common shareholders—basic and diluted	$ (11,802)	$ (6,359)	$ (24,403)	$ (11,197)
Denominator:
Weighted-average common shares outstanding—basic and diluted	4,825,214	1,528,374	3,229,635	1,528,374
Net loss per share attributable to common shareholders—basic and diluted	$ (2.45)	$ (4.16)	$ (7.56)	$ (7.33)

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
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	4,099,545	1,920,950	4,099,545	1,920,950
Series A Preferred Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount		11,090,135		11,090,135

Significant Agreements and Commitments - Additional Information (Details) - USD ($)	1 Months Ended			6 Months Ended
	Jul. 31, 2020	Apr. 30, 2020	Mar. 31, 2020	Jun. 30, 2020
Directors and Officers Liability Insurance \| Subsequent Event
Significant Agreements And Commitments [Line Items]
Liability for insurance policies for total aggregate premium of including excise tax	$ 6,420,000
Directors and Officers Liability Insurance \| General and Administrative Expense
Significant Agreements And Commitments [Line Items]
Liability for insurance policies for total aggregate premium of including excise tax				$ 6,420,000
Directors and Officers Liability Insurance \| Accrued Expenses And Other Current Liabilities
Significant Agreements And Commitments [Line Items]
Liability for insurance policies for recognized				$ 270,000
Directors and Officers Liability Insurance \| Prepaid Expenses and Other Current Assets \| Subsequent Event
Significant Agreements And Commitments [Line Items]
Liability for insurance policies for recognized	$ 6,150,000
MDACC \| Preclinical Studies and Clinical Trials
Significant Agreements And Commitments [Line Items]
Contractual obligation			$ 10,000,000
Contractual obligation period			5 years
Contractual obligation paid		$ 2,000,000

Subsequent Events - Additional Information (Details) - Subsequent Event - Board of Directors - Employees Stock Options - 2020 Equity Incentive Plan	Aug. 13, 2020 $ / shares shares
Subsequent Event [Line Items]
Number of shares authorized to be issued \| shares	30,199
Weighted average exercise price per share \| $ / shares	$ 24.00