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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K ( Mark One ) ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM ΤΟ Commission File Number 001-39335 Repare Therapeutics Inc. ( Exact name of Registrant as specified in its Charter ) Québec ( State or other jurisdiction of incorporation or organization ) 7210 Frederick - Banting , Suite 100 St - Laurent , Québec , Canada ( Address of principal executive offices ) Securities registered pursuant to Section 12 ( b ) of the Act : Registrant's telephone number , including area code : ( 857 ) 412-7018 Title of each class Common Shares , no par value Not applicable ( I.R.S. Employer Identification No. ) Trading Symbol ( s ) RPTX H4S 2A1 ( Zip Code ) Name of each exchange on which registered The Nasdaq Stock Market LLC Securities registered pursuant to Section 12 ( g ) of the Act : None Indicate by check mark if the Registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . YESNO > Indicate by check mark if the Registrant is not required to file reports pursuant to Section 13 or 15 ( d ) of the Act . YES NO Indicate by check mark whether the Registrant : ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 during the preceding 12 months ( or for such shorter period that the Registrant was required to file such reports ) , and ( 2 ) has been subject to such filing requirements for the past 90 days . YES > NO Indicate by check mark whether the Registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S - T ( §232.405 of this chapter ) during the preceding 12 months ( or for such shorter period that the Registrant was required to submit such files ) . YES > NO Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , smaller reporting company , or an emerging growth company . See the definitions of " large accelerated filer , " " accelerated filer , " " smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . Large accelerated filer Accelerated filer Non - accelerated filer Smaller reporting company U X Emerging growth company If an emerging growth company , indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13 ( a ) of the Exchange Act . Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404 ( b ) of the Sarbanes - Oxley Act ( 15 U.S.C. 7262 ( b ) ) by the registered public accounting firm that prepared or issued its audit report . Indicate by check mark whether the Registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . YES NO The aggregate market value of the registrant's common shares held by non - affiliates was $ 703,850,221 as of June 30 , 2020 , based on a total of 22,690,207 common shares held by non affiliates and a closing price of $ 31.02 as reported on The Nasdaq Stock Market on June 30 , 2020. For purposes of this computation , all officers , directors and 10 % beneficial owners of the registrant are deemed to be affiliates . Such determination should not be an admission that such officers , directors and 10 % beneficial owners are , in fact , affiliates of the registrant . The number of shares of registrant's common shares outstanding as of March 1 , 2021 was 36,904,446 . DOCUMENTS INCORPORATED BY REFERENCE Portions of the definitive proxy statement for the registrant's 2021 annual meeting of shareholders , which is to be filed within 120 days after the end of the registrant's fiscal year ended December 31 , 2020 , are incorporated by reference into Part III of this Form 10 - K , to the extent described in Part III .