X0306 4 2020-06-23 0 0001808158 Repare Therapeutics Inc. RPTX 0001572451 Bonita David P C/O REPARE THERAPEUTICS INC. 7210 FREDERICK-BANTING, SUITE 100 ST-LAURENT A8 H4S 2A1 QUEBEC, CANADA 1 0 0 0 Common Shares 2020-06-23 4 C 0 2601325 A 2601325 I See Footnote Common Shares 2020-06-23 4 P 0 675000 20.00 A 3276325 I See Footnote Common Shares 2020-06-23 4 P 0 99200 20.00 A 99200 I See Footnote Class B Preferred Shares 2020-06-23 4 C 0 2601325 D Common Shares 2601325 0 I See Footnote Each Series B Preferred Share converted into the same number of Common Shares upon the closing of the Issuer's initial public offering and had no expiration date. These securities are held of record by OrbiMed Private Investments VII, LP ("OPI VII"). OrbiMed Capital GP VII LLC ("OrbiMed GP VII") is the general partner of OPI VII and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of OrbiMed GP VII. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, OrbiMed GP VII and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VII and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Capital LLC ("OrbiMed Capital") is a relying advisor of OrbiMed Advisors. OrbiMed Advisors and OrbiMed Capital exercise voting and investment power through a management committee comprised of the Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VII. These securities are held of record by OrbiMed Partners Master Fund Limited ("OPM"). OrbiMed Capital is the investment advisor to OPM. OrbiMed Capital is a relying advisor of OrbiMed Advisors. OrbiMed Advisors and OrbiMed Capital exercise voting and investment power through a management committee comprised of the Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPM. /s/ Steve Forte, Attorney-in-Fact 2020-06-25