SCHEDULE 13G/A 0000947871-24-000915 0001055951 XXXXXXXX LIVE 3 Common Stock, par value $0.0001 per share 12/31/2025 0001662579 C4 Therapeutics, Inc. 12529R107 490 ARSENAL WAY SUITE 120 Watertown MA 02472 Rule 13d-1(b) OrbiMed Advisors LLC DE 0.00 521368.00 0.00 521368.00 521368.00 N 0.5 IA OrbiMed Capital LLC DE 883534.00 0.00 883534.00 0.00 883534.00 N 1.0 IA C4 Therapeutics, Inc. 490 Arsenal Way, Suite 120 Watertown, MA 02472 OrbiMed Advisors LLC OrbiMed Capital LLC 601 Lexington Avenue, 54th Floor New York, NY 10022 Please refer to Item 4 on each cover sheet for each filing person. N IA OrbiMed Advisors LLC: 521,368 OrbiMed Capital LLC: 883,534 OrbiMed Advisors LLC: 0.5% OrbiMed Capital LLC: 1.0% OrbiMed Advisors LLC: 0 OrbiMed Capital LLC: 883,534 OrbiMed Advisors LLC: 521,368 OrbiMed Capital LLC: 0 OrbiMed Advisors LLC: 0 OrbiMed Capital LLC: 883,534 OrbiMed Advisors LLC: 521,368 OrbiMed Capital LLC: 0 N Y N The Reporting Persons hold 1.5% of the shares of Common Stock in the aggregate on behalf of other persons who have the right to receive or the power to direct the receipt of dividends from, or proceeds from the sale of, such securities. OrbiMed Advisors LLC and OrbiMed Capital LLC exercise investment and voting power over the shares of Common Stock through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares of Common Stock reported herein. Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and 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. OrbiMed Advisors LLC /s/ Carl L. Gordon 02/17/2026 OrbiMed Capital LLC /s/ Carl L. Gordon 02/17/2026