SCHEDULE 13D/A 0001589097 XXXXXXXX LIVE 6 Common Shares 11/19/2025 false 0001808158 760273102 Repare Therapeutics Inc.

7171 Frederick Banting Building 2, Suite 270 Saint-Laurent, Quebec Z4 H4S 1Z9

Max Eisenberg 415-801-8100 One Sansome Street Suite 1650 San Francisco CA 94104 0001589097 N Versant Venture Capital V, L.P. b WC N DE 0 0 0 0 0 N 0.0 PN 0001589095 N Versant Affiliates Fund V, L.P. b WC N DE 2693 0 2693 0 2693 N 0.0 PN All shares are held by VAF V (as defined in Item 2(a) of the Original 13D (as defined in Item 1 below)). VV V (as defined in Item 2(a) of the Original 13D) is the sole general partner of VAF V and may be deemed to have voting and dispositive power over the securities held by VAF V and as a result may be deemed to have beneficial ownership over such securities. The percentage in Row 13 is based on 42,985,755 Common Shares (as defined in Item 1 of the Original 13D) outstanding as of October 31, 2025, as set forth in the Issuer's quarterly report on Form 10-Q for the quarter ended September 30, 2025, filed with the United States Securities and Exchange Commission (the "Commission") on November 14, 2025 (the "Form 10-Q"). 0001589098 N Versant Ophthalmic Affiliates I, L.P. b WC N DE 2982 0 2982 0 2982 N 0.0 PN All shares are held by VOA (as defined in Item 2(a) of the Original 13D). VV V is the sole general partner of VOA and may be deemed to have voting and dispositive power over the securities held by VOA and as a result may be deemed to have beneficial ownership over such securities. The percentage in Row 13 is based on 42,985,755 Common Shares outstanding as of October 31, 2025, as reported in the Form 10-Q. 0001619298 N Versant Ventures V, LLC b AF N DE 0 5675 0 5675 5675 N 0.0 OO The shares reported in Rows 8 and 10 consist of (i) 2,693 Common Shares held by VAF V and (ii) 2,982 Common Shares held by VOA. VV V is the sole general partner of each of VAF V and VOA and may be deemed to have voting and dispositive power over the securities held by each of VAF V and VOA. The percentage in Row 13 is based on 42,985,755 Common Shares outstanding as of October 31, 2025, as reported in the Form 10-Q. 0001612235 N Versant Venture Capital V (Canada) LP b WC N A6 6814 0 6814 0 6814 N 0.0 PN All shares held by VVC CAN (as defined in Item 2(a) of the Original 13D). VV V CAN GP (as defined in Item 2(a) of the Original 13D) is the sole general partner of VV V CAN (as defined in Item 2(a) of the Original 13D), and VV V CAN is the sole general partner of VVC CAN. Each of VV V CAN GP and VV V CAN share voting and dispositive power over the shares held by VVC CAN and as a result may be deemed to have beneficial ownership over such securities. The percentage in Row 13 is based on 42,985,755 Common Shares outstanding as of October 31, 2025, as reported in the Form 10-Q. 0001716490 N Versant Ventures V (Canada), L.P. b AF N DE 0 6814 0 6814 6814 N 0.0 PN All shares held by VVC CAN. VV V CAN GP is the sole general partner of VV V CAN, and VV V CAN is the sole general partner of VVC CAN. Each of VV V CAN GP and VV V CAN share voting and dispositive power over the shares held by VVC CAN and as a result may be deemed to have beneficial ownership over such securities. The percentage in Row 13 is based on 42,985,755 Common Shares outstanding as of October 31, 2025, as reported in the Form 10-Q. 0001619297 N Versant Ventures V GP-GP (Canada), Inc. b AF N DE 0 6814 0 6814 6814 N 0.0 CO All shares held by VVC CAN. VV V CAN GP is the sole general partner of VV V CAN, and VV V CAN is the sole general partner of VVC CAN. Each of VV V CAN GP and VV V CAN share voting and dispositive power over the shares held by VVC CAN and as a result may be deemed to have beneficial ownership over such securities. The percentage in Row 13 is based on 42,985,755 Common Shares outstanding as of October 31, 2025, as reported in the Form 10-Q. 0001687880 N Versant Venture Capital VI, L.P. b WC N DE 0 0 0 0 0 N 0.0 PN 0001777654 N Versant Ventures VI GP, L.P. b AF N DE 0 0 0 0 0 N 0.0 PN 0001777652 N Versant Ventures VI GP-GP, LLC b AF N DE 0 0 0 0 0 N 0.0 OO 0001765253 N Versant Vantage I, L.P. b WC N DE 72211 0 72211 0 72211 N 0.2 PN All shares are held by Vantage LP (as defined in Item 2(a) of the Original 13D). Vantage LLC (as defined in the Original 13D) is the general partner of Vantage GP (as defined in Item 2(a) of the Original 13D), which is the general partner of Vantage LP. Each of Vantage LLC and Vantage GP share voting and dispositive power over the shares held by Vantage LP and as a result may be deemed to have beneficial ownership over such securities. The percentage in Row 13 is based on 42,985,755 Common Shares outstanding as of October 31, 2025, as reported in the Form 10-Q. 0001777651 N Versant Vantage I GP, L.P. b AF N DE 0 72211 0 72211 72211 N 0.2 PN All shares are held by Vantage LP. Vantage LLC is the general partner of Vantage GP, which is the general partner of Vantage LP. Each of Vantage LLC and Vantage GP share voting and dispositive power over the shares held by Vantage LP and as a result may be deemed to have beneficial ownership over such securities. The percentage in Row 13 is based on 42,985,755 Common Shares outstanding as of October 31, 2025, as reported in the Form 10-Q. 0001777653 N Versant Vantage I GP-GP, LLC b AF N DE 0 72211 0 72211 72211 N 0.2 OO All shares are held by Vantage LP. Vantage LLC is the general partner of Vantage GP, which is the general partner of Vantage LP. Each of Vantage LLC and Vantage GP share voting and dispositive power over the shares held by Vantage LP and as a result may be deemed to have beneficial ownership over such securities. The percentage in Row 13 is based on 42,985,755 Common Shares outstanding as of October 31, 2025, as reported in the Form 10-Q. Common Shares Repare Therapeutics Inc. 7171 Frederick Banting Building 2, Suite 270 Saint-Laurent, Quebec Z4 H4S 1Z9 This Amendment No. 6 (this "Amendment") amends and supplements the Schedule 13D originally filed by the Reporting Persons with the Commission on July 7, 2020, as amended by Amendment No. 1 filed with the Commission on January 25, 2021, Amendment No. 2 filed with the Commission on February 26, 2021, Amendment No. 3 filed with the Commission on August 16, 2021, Amendment No. 4 filed with the Commission on June 13, 2022 and Amendment No. 5 filed with the Commission on January 6, 2023 (collectively, the "Original 13D"). Only those items that are hereby reported are amended; all other items reported in the Original 13D remain unchanged. Information given in response to each item shall be deemed incorporated by reference in all other items, as applicable. Capitalized terms not defined in this Amendment have the meanings ascribed to them in the Original 13D. One Sansome Street, Suite 1650, San Francisco, CA 94104 See Items 7-11 and 13 of the cover pages of this Amendment for each Reporting Person and the corresponding comments. See Items 7-11 and 13 of the cover pages of this Amendment for each Reporting Person and the corresponding comments. On November 19, 2025, VVC V sold 44,594 Common Shares at a price per share of $2.1605 for aggregate proceeds of approximately $96,345.34. On November 19, 2025, Versant VI sold 331,558 Common Shares at a price per share of $2.1605 for aggregate proceeds of approximately $716,331.06. On November 20, 2025, VVC V sold 237,107 Common Shares at a price per share of $2.1064 for aggregate proceeds of approximately $499,442.18. On November 20, 2025, Versant VI sold 1,762,893 Common Shares at a price per share of $2.1064 for aggregate proceeds of approximately $3,713,357.82. On November 20, 2025, Vantage LP sold 4,006 Common Shares at a price per share of $2.1275 for aggregate proceeds of approximately $8,522.77. On November 21, 2025, VAF V sold 5,782 Common Shares at a price per share of $2.1357 for aggregate proceeds of approximately $12,348.53. On November 21, 2025, VOA sold 6,399 Common Shares at a price per share of $2.1357 for aggregate proceeds of approximately $13,666.25. On November 21, 2025, VVC CAN sold 14,624 Common Shares at a price per share of $2.1357 for aggregate proceeds of approximately $31,232.26. On November 21, 2025, Vantage LP sold 154,994 Common Shares at a price per share of $2.1357 for aggregate proceeds of approximately $331,018.36. November 20, 2025 Versant Venture Capital V, L.P. /s/ Max Eisenberg 11/21/2025 Versant Affiliates Fund V, L.P. /s/ Max Eisenberg 11/21/2025 Versant Ophthalmic Affiliates I, L.P. /s/ Max Eisenberg 11/21/2025 Versant Ventures V, LLC /s/ Max Eisenberg 11/21/2025 Versant Venture Capital V (Canada) LP /s/ Max Eisenberg 11/21/2025 Versant Ventures V (Canada), L.P. /s/ Max Eisenberg 11/21/2025 Versant Ventures V GP-GP (Canada), Inc. /s/ Max Eisenberg 11/21/2025 Versant Venture Capital VI, L.P. /s/ Max Eisenberg 11/21/2025 Versant Ventures VI GP, L.P. /s/ Max Eisenberg 11/21/2025 Versant Ventures VI GP-GP, LLC /s/ Max Eisenberg 11/21/2025 Versant Vantage I, L.P. /s/ Max Eisenberg 11/21/2025 Versant Vantage I GP, L.P. /s/ Max Eisenberg 11/21/2025 Versant Vantage I GP-GP, LLC /s/ Max Eisenberg 11/21/2025