SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

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☐ Preliminary Proxy Statement

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☐ Definitive Proxy Statement

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☐ Soliciting Material Pursuant to § 240.14a-12

REPARE THERAPEUTICS INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement if Other Than the Registrant)

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P.O. BOX 8016, CARY, NC 27512-9903 Repare Therapeutics Inc. Important Notice Regarding the Availability of Proxy Materials Shareholders Meeting to be held on June 8, 2023 For Shareholders of record as of April 10, 2023 complete This communication proxy materials presents that only are available an overview to you of the on the more Internet. This We encourage is not a ballot you. to You access cannot and use review this notice all of the to vote important your shares. information appoint a third contained party proxyholder, in the proxy a materials shareholder before of record voting ..must    To return provided its in proxy the proxy card by materials mail in accordance by no later than with by the 10:00 instructions A.M., Eastern Time, on June 6, 2023. To view the proxy materials, and to obtain directions to attend the meeting, go to: www.proxydocs.com/RPTX To vote your proxy while visiting this site, you will need the 12 digit control number in the box below. Under United States Securities and Exchange Commission rules, proxy materials do not have to be delivered in paper. Proxy materials can be distributed by making them available on the internet. For a convenient way to view proxy materials and VOTE go to www.proxydocs.com/RPTX Have the 12 digit control number located in the shaded box above available when you access the website and follow the instructions. If is you no charge want to to receive you for a requesting paper or e—amail copy copy . In order of the to proxy receive materials, a paper you package must request in time for one the . There deadline request on to or submit before voting 5:00 instructions, PM, Eastern as Time, applicable, on May and 26, 2023 this year’s . meeting, you must make this To order paper materials, use one of the following methods. INTERNET TELEPHONE * E-MAIL www.investorelections.com/RPTX (866) 648-8133 paper@investorelections.com When requesting via the Internet or telephone you will need the 12 digit * If requesting material by e-mail, please send a blank e-mail with the 12 digit control number (located above) control number located in the shaded box above. in the subject line. No other requests, instructions OR other inquiries should be included with your e-mail requesting material. Repare Therapeutics Inc. Meeting Type: Annual Meeting of Shareholders Date: Thursday, June 8, 2023 Time: 10:00 AM, Eastern Time Place: Annual Meeting to be held live via the Internet—please visit www.proxydocs.com/RPTX for more details. For information about this notice, please call (888) 464-5457. You must pre-register to attend the meeting online and/or participate at www.proxydocs.com/RPTX. SEE REVERSE FOR FULL AGENDA

Repare Therapeutics Inc. Annual Meeting of Shareholders THE BOARD OF DIRECTORS RECOMMENDS A VOTE FOR EACH OF THE DIRECTOR NOMINEES LISTED IN PROPOSAL 1 AND FOR PROPOSALS 2 AND 3 PROPOSAL 1. To elect our three nominees as Class III directors: Samarth Kulkarni, Ph.D., Briggs Morrison, M.D. and Lloyd M. Segal, to our board of directors, each to hold office until our Annual Meeting of Shareholders in 2026. 1.01 Samarth Kulkarni, Ph.D. 1.02 Briggs Morrison, M.D. 1.03 Lloyd M. Segal 2. To approve, on an advisory basis, the compensation of the Company’s named executive officers, as disclosed in this proxy statement. 3. To appoint Ernst & Young LLP as the independent registered public accounting firm of the Company for its fiscal year ending December 31, 2023, and to authorize the Company’s board of directors to fix Ernst & Young LLP’s remuneration. NOTE: To conduct any other business properly brought before the Annual Meeting For additional information, see “Proposal 1: Election of Directors”, “Proposal 2: Advisory Vote On Executive Compensation”, and “Proposal 3: Ratification of Selection of Independent Registered Public Accounting Firm” of the proxy statement for the 2023 Annual Meeting of Shareholders of Repare Therapeutics Inc.