SCHEDULE 13G/A 0001831942-25-000016 0001831942 XXXXXXXX LIVE 1 Common Stock, $0.001 Par Value 09/30/2025 0001622229 Cogent Biosciences, Inc. 19240Q201 275 Wyman Street 3rd Floor Waltham MA 02451 Rule 13d-1(c) Commodore Capital LP DE 0.00 10208060.00 0.00 10208060.00 10208060.00 7.2 IA PN Commodore Capital Master LP E9 0.00 10208060.00 0.00 10208060.00 10208060.00 7.2 PN Robert Egen Atkinson X1 0.00 10208060.00 10208060.00 0.00 10208060.00 7.2 HC IN Michael Kramarz X1 0.00 10208060.00 0.00 10208060.00 10208060.00 7.2 HC IN Cogent Biosciences, Inc. 275 Wyman Street, 3rd Floor, Waltham, MASSACHUSETTS, 02451. Commodore Capital LP Commodore Capital Master LP Robert Egen Atkinson Michael Kramarz Each a "Filer." The address for Commodore Capital LP, Robert Egen Atkinson, and Michael Kramarz is 444 Madison Avenue, Floor 35, New York, NY 10022. The address for Commodore Capital Master LP is c/o Maples Corporate Services Limited, Ugland House, South Church Street, PO Box 309, Grand Cayman KY1-1104, Cayman Islands. See Item 4 of the cover page for each Filer. Y See Item 9 of the cover page for each Filer. This report on Schedule 13G is being filed by Commodore Capital LP (the "Firm"), Commodore Capital Master LP ("Commodore Master"), Michael Kramarz, and Robert Egen Atkinson. The Firm is the investment manager to Commodore Master. As of September 30, 2025, the Firm may be deemed to beneficially own an aggregate of 10,208,060 shares Common Stock, $0.001 Par Value per share (the "Common Stock"), of Cogent Biosciences, Inc. (the "Issuer"), consisting of (i) 7,250,000 shares of Common Stock (ii) 2,352,000 shares of Common Stock underlying Series B Non-Voting Convertible Preferred Stock, which is subject to a beneficial ownership limitation of 9.99%, and (iii) 606,060 shares of Common Stock underlying a warrant which is subject to a beneficial ownership limitation of 9.99%. The Firm, as the investment manager to Commodore Master, may be deemed to beneficially own these securities. Michael Kramarz and Robert Egen Atkinson are the managing partners of the Firm and exercise investment discretion with respect to these securities. Ownership percentages are based on 139,827,662 Common Shares reported as issued and outstanding as of September 30, 2025 in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 7, 2025, plus 2,352,000 shares of Common Stock underlying Series B Non-Voting Convertible Preferred Stock and 606,060 shares of Common Stock which the Filers may acquire upon the exercise of the warrants, subject to the beneficial ownership limitation of 9.99%. See Item 11 of the cover page for each Filer. See Item 5 of the cover page for each Filer. See Item 6 of the cover page for each Filer. See Item 7 of the cover page for each Filer. See Item 8 of the cover page for each Filer. Y Y Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11. Exhibit 1: Joint Filing Agreement Commodore Capital LP Michael Kramarz 11/14/2025 Commodore Capital Master LP Michael Kramarz 11/14/2025 Robert Egen Atkinson Robert Egen Atkinson 11/14/2025 Michael Kramarz Michael Kramarz 11/14/2025