X0306 4 2021-05-28 0 0001808158 Repare Therapeutics Inc. RPTX 0001473930 Foley Todd C/O MPM CAPITAL 450 KENDALL STREET CAMBRIDGE MA 02142 1 0 0 0 Common Shares 2021-05-28 4 S 0 7377 32.67 D 2393081 I See Footnote Common Shares 2021-06-01 4 S 0 6671 32.50 D 2386410 I See Footnote Common Shares 2021-06-02 4 S 0 2608 31.83 D 2383802 I See Footnote Common Shares 2021-06-02 4 S 0 130 32.42 D 2383672 I See Footnote Transaction effected pursuant to a plan established pursuant to Rule 10b5-1 on 3/31/2021. The shares were sold as follows: 7,131 by MPM BioVentures 2014, L.P. ("BV 2014") and 246 by MPM Asset Management Investors BV2014 LLC ("AM BV2014"). The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $32.04 to $32.89 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. The shares are held as follows: 2,182,128 by BV 2014, 135,843 by MPM BioVentures 2014(B), L.P. ("BV 2014(B)") and 75,110 by AM BV2014. MPM BioVentures 2014 GP LLC and MPM BioVentures 2014 LLC ("BV LLC") are the direct and indirect general partners of BV 2014 and BV 2014(B). BV LLC is the manager of AM BV2014. Todd Foley is a managing director of BV LLC. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein. The shares were sold as follows: 6,449 by BV 2014 and 222 by AM BV2014. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $32.12 to $32.98 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. The shares are held as follows: 2,175,679 by BV 2014, 135,843 by BV 2014(B) and 74,888 by AM BV2014. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein. The shares were sold as follows: 2,521 by BV 2014 and 87 by AM BV2014. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $31.29 to $32.24 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. The shares are held as follows: 2,173,158 by BV 2014, 135,843 by BV 2014(B) and 74,801 by AM BV2014. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein. The shares were sold as follows: 126 by BV 2014 and 4 by AM BV2014. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $32.31 to $32.58 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. The shares are held as follows: 2,173,032 by BV 2014, 135,843 by BV 2014(B) and 74,797 by AM BV2014. The Reporting Person disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein. /s/ Todd Foley 2021-06-02