Sec Form 4 Filing - ORBIMED ADVISORS LLC @ Adicet Bio, Inc. - 2023-06-27

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person ORBIMED ADVISORS LLC 2. Issuer Name and Ticker or Trading Symbol Adicet Bio, Inc. [ ACET] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 601 LEXINGTON AVENUE, 54TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 06/27/2023 (Street) NEW YORK, NY10022 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 06/27/2023 P 125,000 A $ 2.09 ( 1 ) 1,027,885 I See footnotes ( 2 ) ( 7 ) Common Stock 06/27/2023 P 250,000 A $ 2.09 ( 1 ) 646,657 I See footnotes ( 3 ) ( 7 ) Common Stock 06/27/2023 P 442,000 A $ 2.09 ( 1 ) 5,685,259 I See footnotes ( 4 ) ( 7 ) Common Stock 06/27/2023 P 58,000 A $ 2.09 ( 1 ) 748,054 I See footnotes ( 5 ) ( 7 ) Common Stock 214,285 I See footnotes ( 6 ) ( 7 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other ORBIMED ADVISORS LLC 601 LEXINGTON AVENUE 54TH FLOOR NEW YORK, NY10022 X X OrbiMed Capital GP V LLC 601 LEXINGTON AVENUE 54TH FLOOR NEW YORK, NY10022 X X OrbiMed Capital GP VI LLC 601 LEXINGTON AVENUE 54TH FLOOR NEW YORK, NY10022 X X OrbiMed Genesis GP LLC 601 LEXINGTON AVENUE 54TH FLOOR NEW YORK, NY10022 X X OrbiMed Advisors Israel II Ltd 5 HAHOSHLIM STREET, BUILDING B 1ST FLOOR HERZLIYA PITUACH, L3 X X OrbiMed Israel GP II, L.P. 5 HAHOSHLIM STREET, BUILDING B 1ST FLOOR HERZLIYA PITUACH, L3 X X OrbiMed Israel GP Ltd. 5 HAHOSHLIM STREET, BUILDING B 1ST FLOOR HERZLIYA PITUACH, L3 X X OrbiMed Israel BioFund GP Limited Partnership 5 HAHOSHLIM STREET, BUILDING B 1ST FLOOR HERZLIYA PITUACH, L3 X X Chimovits Erez 5 HAHOSHLIM STREET, BUILDING B 1ST FLOOR HERZLIYA PITUACH, L3 X X Signatures /s/ Carl L. Gordon, Member of OrbiMed Advisors LLC 06/29/2023 Signature of Reporting Person Date /s/ Carl L. Gordon, Member of OrbiMed Capital GP V LLC 06/29/2023 Signature of Reporting Person Date /s/ Carl L. Gordon, Member of OrbiMed Capital GP VI LLC 06/29/2023 Signature of Reporting Person Date /s/ Carl L. Gordon, Member of OrbiMed Genesis GP LLC 06/29/2023 Signature of Reporting Person Date /s/ Carl L. Gordon, Director of OrbiMed Israel GP Ltd. 06/29/2023 Signature of Reporting Person Date /s/ Carl L. Gordon, Director of OrbiMed Advisors Israel II Ltd. 06/29/2023 Signature of Reporting Person Date /s/ Carl L. Gordon, Director of OrbiMed Israel GP II, L.P. 06/29/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents the weighted average purchase price of the shares of common stock purchased, ranging from a low of $2.08 to a high of $2.12 per share. The Reporting Persons undertake, upon request by the staff of the Securities and Exchange Commission, the Issuer or a security holder of the Issuer, to provide full information regarding the number of shares purchased at each separate price. ( 2 )These shares of the Issuer's common stock are held of record by OrbiMed Israel Partners Limited Partnership ("OIP"). OrbiMed Israel BioFund GP Limited Partnership ("OrbiMed BioFund") is the general partner of OIP, and OrbiMed Israel GP Ltd. ("OrbiMed Israel GP") is the general partner of OrbiMed BioFund. By virtue of such relationships, OrbiMed BioFund and OrbiMed Israel GP may be deemed to have voting and investment power over the shares of common stock held by OIP and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Israel GP exercises this investment and voting power through an investment committee comprised of Carl L. Gordon and Erez Chimovits, each of whom disclaims beneficial ownership over the shares of common stock held by OIP. ( 3 )These shares of the Issuer's common stock are held of record by OrbiMed Israel Partners II, L.P. ("OIP II"). OrbiMed Israel GP II, L.P. ("OrbiMed Israel GP II") is the general partner of OIP II, and OrbiMed Advisors Israel II Limited ("OrbiMed Israel II") is the general partner of OrbiMed Israel GP II. By virtue of such relationships, OrbiMed Israel GP II and OrbiMed Israel II may be deemed to have voting and investment power over the shares of common stock held by OIP II and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Israel II exercises this investment and voting power through an investment committee comprised of Carl L. Gordon, David Bonita, and Erez Chimovits, each of whom disclaims beneficial ownership over the shares of common stock held by OIP II. ( 4 )These shares of the Issuer's common stock are held of record by OrbiMed Private Investments V, LP ("OPI V"). OrbiMed Capital GP V LLC ("GP V") is the general partner of OPI V, and OrbiMed Advisors LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisors Act of 1940, as amended, is the managing member of GP V. By virtue of such relationships, GP V and OrbiMed Advisors may be deemed to have voting and investment power over the shares of common stock held by OPI V and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership over the shares of common stock held by OPI V. ( 5 )These shares of the Issuer's common stock are held of record by OrbiMed Private Investments VI, LP ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI, and OrbiMed Advisors is the managing member of GP VI. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting and investment power over the shares of common stock held by OPI VI and, as a resu lt, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership over the shares of common stock held by OPI VI. ( 6 )These shares of the Issuer's common stock are held of record by OrbiMed Genesis Master Fund, L.P. ("Genesis"). OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis, and OrbiMed Advisors is the managing member of Genesis. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting and investment power over the shares of common stock held by Genesis and, as a result, may be deemed to have beneficial ownership over such shares of common stock. OrbiMed Advisors exercises this investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership over the shares of common stock held by Genesis. ( 7 )Each of OrbiMed Advisors, OrbiMed BioFund, OrbiMed Israel GP, OrbiMed Israel GP II, OrbiMed Israel II, GP V, GP VI, Genesis GP, and Erez Chimovits disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of his or its pecuniary interest therein, if any. OrbiMed Advisors, GP V and GP VI have designated a representative, Carl L. Gordon, a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any such person or entity is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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