X0202 SCHEDULE 13G/A 0001104659-24-010651 0001346824 XXXXXXXX LIVE 3 Common Stock, par value $0.0001 per share 02/17/2026 0001720580 Adicet Bio, Inc. 007002207 131 Dartmouth Street, Floor 3 Boston MA 02116 Rule 13d-1(c) RA Capital Management, L.P. DE 0.00 1182624.00 0.00 1182624.00 1182624.00 12.3 IA PN Peter Kolchinsky X1 0.00 1182624.00 0.00 1182624.00 1182624.00 12.3 HC IN Rajeev Shah X1 0.00 1182624.00 0.00 1182624.00 1182624.00 12.3 HC IN RA Capital Healthcare Fund, L.P. DE 0.00 1182624.00 0.00 1182624.00 1182624.00 12.3 PN Adicet Bio, Inc. 131 Dartmouth Street, Floor 3, Boston, MA, 02116. The names of the persons filing this report (collectively, the "Reporting Persons") are: RA Capital Management, L.P. ("RA Capital") Peter Kolchinsky Rajeev Shah RA Capital Healthcare Fund, L.P. (the "Fund") The Reporting Persons expressly disclaim status as a "group" for purposes of this Schedule 13G/A. The address of the principal business office of each of the Reporting Persons is: c/o RA Capital Management, L.P., 200 Berkeley Street, 18th Floor, Boston MA 02116 RA Capital and the Fund are Delaware limited partnerships. Dr. Kolchinsky and Mr. Shah are United States citizens. Y Row 9 of each Reporting Person's cover page to this Schedule 13G/A sets forth the aggregate number of shares of common stock of the Issuer beneficially owned by such Reporting Person and is incorporated by reference. The Fund directly holds (i) 1,182,624 shares of common stock, and (ii) pre-funded warrants (the "Pre- Funded Warrants") exercisable for an aggregate of up to 1,152,833 shares of common stock. The Pre-Funded Warrants contain a provision (the "Beneficial Ownership Blocker"), which precludes the exercise of the Pre-Funded Warrants to the extent that, following exercise, the Fund, together with its affiliates and other attribution parties, would own more than 9.99% of the common stock outstanding. The Fund is currently prohibited from exercising the Pre-Funded Warrants by virtue of the Beneficial Ownership Blocker. RA Capital Healthcare Fund GP, LLC is the general partner of the Fund. The general partner of RA Capital is RA Capital Management GP, LLC, of which Dr. Kolchinsky and Mr. Shah are the controlling persons. RA Capital serves as investment adviser for the Fund and may be deemed a beneficial owner, for purposes of Section 13(d) of the Act, of any securities of the Issuer held by the Fund. The Fund has delegated to RA Capital the sole power to vote and the sole power to dispose of all securities held in the Fund's portfolio, including the shares of the Issuer's common stock reported herein. Because the Fund has divested voting and investment power over the reported securities it holds and may not revoke that delegation on less than 61 days' notice, the Fund disclaims beneficial ownership of the securities it holds for purposes of Section 13(d) of the Act. As managers of RA Capital, Dr. Kolchinsky and Mr. Shah may be deemed beneficial owners, for purposes of Section 13(d) of the Act, of any securities of the Issuer beneficially owned by RA Capital. RA Capital, Dr. Kolchinsky, and Mr. Shah disclaim beneficial ownership of the securities reported in this Schedule 13G/A other than for the purpose of determining their obligations under Section 13(d) of the Act, and the filing of this Schedule 13G/A shall not be deemed an admission that either RA Capital, Dr. Kolchinsky, or Mr. Shah is the beneficial owner of such securities for any other purpose. Row 11 of each Reporting Person's cover page to this Schedule 13G/A sets forth the percentages of the shares of common stock of the Issuer beneficially owned by such Reporting Person and is incorporated by reference. The percentage set forth in each row 11 is based upon 9,596,407 shares of common stock outstanding as of March 10, 2026, as reported in the Issuer's Annual Report on Form 10-K filed with the Securities and Exchange Commission (the "SEC") on March 12, 2026. Row 5 of each Reporting Person's cover page to this Schedule 13G/A sets forth the sole power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person and is incorporated by reference. Row 6 of each Reporting Person's cover page to this Schedule 13G/A sets forth the shared power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person and is incorporated by reference. Row 7 of each Reporting Person's cover page to this Schedule 13G/A sets forth the sole power to dispose or to direct the disposition of securities of the Issuer beneficially owned by such Reporting Person and is incorporated by reference. Row 8 of each Reporting Person's cover page to this Schedule 13G/A sets forth the shared power to dispose or to direct the disposition of securities of the Issuer beneficially owned by such Reporting Person and is incorporated by reference. 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 99.1 Joint Filing Agreement (incorporated by reference to Exhibit 1 to Schedule 13G/A filed on November 14, 2024) RA Capital Management, L.P. /s/ Peter Kolchinsky 04/13/2026 Peter Kolchinsky /s/ Peter Kolchinsky 04/13/2026 Rajeev Shah /s/ Rajeev Shah 04/13/2026 RA Capital Healthcare Fund, L.P. /s/ Peter Kolchinsky 04/13/2026