X0202 SCHEDULE 13G/A 0001352546 XXXXXXXX LIVE 2 Common Stock 06/30/2026 0001622229 Cogent Biosciences, Inc. 19240Q201 275 Wyman Street, 3rd Floor Waltham MA 02451 Rule 13d-1(c) Deerfield Mgmt, L.P. b DE 5006104.00 0.00 5006104.00 0.00 5006104.00 N 2.88 PN Comprised of shares of common stock held by Deerfield Partners, L.P., of which Deerfield Mgmt, L.P. is the general partner. Deerfield Management Company, L.P. b DE 5006104.00 0.00 5006104.00 0.00 5006104.00 N 2.88 PN Comprised of shares of common stock held by Deerfield Partners, L.P. of which Deerfield Management Company, L.P. is the investment advisor. Deerfield Partners, L.P. b DE 5006104.00 0.00 5006104.00 0.00 5006104.00 N 2.88 PN James E. Flynn b X1 5006104.00 0.00 5006104.00 0.00 5006104.00 N 2.88 IN Comprised of shares of common stock held by Deerfield Partners, L.P. Cogent Biosciences, Inc. 275 Wyman Street, 3rd Floor, Waltham, Massachusetts 02451 James E. Flynn, Deerfield Mgmt, L.P., Deerfield Management Company, L.P. and Deerfield Partners, L.P. James E. Flynn, Deerfield Mgmt, L.P., Deerfield Management Company, L.P. and Deerfield Partners, L.P., 345 Park Avenue South, 12th Floor, New York, NY 10010 Deerfield Mgmt, L.P., Deerfield Management Company, L.P. and Deerfield Partners, L.P. - Delaware limited partnerships; James E. Flynn - United States citizen Y Deerfield Mgmt, L.P. - 5,006,104 shares Deerfield Management Company, L.P. - 5,006,104 shares Deerfield Partners, L.P. - 5,006,104 shares James E. Flynn - 5,006,104 shares Deerfield Mgmt, L.P. - 2.88% Deerfield Management Company, L.P. - 2.88% Deerfield Partners, L.P. - 2.88% James E. Flynn - 2.88% All Reporting Persons - 0 Deerfield Mgmt, L.P. - 5,006,104 Deerfield Management Company, L.P. - 5,006,104 Deerfield Partners, L.P. - 5,006,104 James E. Flynn - 5,006,104 All Reporting Persons - 0 Deerfield Mgmt, L.P. - 5,006,104 Deerfield Management Company, L.P. - 5,006,104 Deerfield Partners, L.P. - 5,006,104 James E. Flynn - 5,006,104 N Y Y Y N See Exhibit B 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 A. Joint Filing Agreement. Exhibit B. Item 8 Statement. Exhibit C. Power of Attorney (1). (1) Power of Attorney previously filed as Exhibit 24 to a Form 3 with regard to BiomX Inc. filed with the Securities and Exchange Commission on March 19, 2024 by Deerfield Private Design Fund V, L.P., Deerfield Healthcare Innovations Fund II, L.P., Deerfield Mgmt V, L.P., Deerfield Mgmt HIF II, L.P., Deerfield Management Company, L.P. and James E. Flynn. Deerfield Mgmt, L.P. /s/ Jonathan Isler 08/13/2026 Deerfield Management Company, L.P. /s/ Jonathan Isler 08/13/2026 Deerfield Partners, L.P. /s/ Jonathan Isler 08/13/2026 James E. Flynn /s/ Jonathan Isler 08/13/2026