Sec Form 4 Filing - Sinclair Andrew @ Adicet Bio, Inc. - 2023-06-01

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 Sinclair Andrew 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 _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O ADICET BIO, INC., 200 BERKELEY STREET, 19TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 06/01/2023 (Street) BOSTON, MA02116 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 06/01/2023 A 5,900 ( 1 ) A $ 0 5,900 D Common Stock 2,115,385 I See Footnote ( 2 ) ( 3 )

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 Stock Option (Right to Buy) $ 5.195 06/01/2023 A 26,400 ( 4 ) 05/31/2033 Common Stock 26,400 $ 0 26,400 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Sinclair Andrew C/O ADICET BIO, INC. 200 BERKELEY STREET, 19TH FLOOR BOSTON, MA02116 X Signatures /s/ Nick Harvey, Attorney-in-Fact 06/02/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Reporting Person was issued Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of Common Stock. The RSUs shall vest in full on the earlier to occur of (a) the first anniversary of the grant date or (b) the date of the next annual meeting of stockholders following the grant date, subject to the Reporting Person's continued service on the Issuer's board of directors. The RSUs may be settled only by delivering shares of Common Stock, and thus, the grant is being reported in Table I as allowed per SEC guidance. ( 2 )These shares are held by Abingworth Bioventures 8 LP ("ABV 8"). Abingworth Bioventures 8 GP LP ("Abingworth GP") serves as the general partner of ABV 8. Abingworth General Partner 8 LLP ("Abingworth GP 8"), serves as the general partner of Abingworth GP. ABV 8 (acting by its general partner Abingworth GP, acting by its general partner Abingworth GP 8) has delegated to Abingworth LLP, all investment and dispositive power over the securities held by ABV 8. The Reporting Person is a Partner and Portfolio Manager of Abingworth LLP. ( 3 )An investment committee approves investment and voting decisions by a majority vote, and no individual member has the sole control or voting power over the shares held by ABV 8. The Reporting Person is a member of the investment committee of ABV 8. From time to time, the investment committee may delegate investment and voting authority over certain securities held by ABV 8 to employees of Abingworth LLP, subject to the supervision and oversight of the investment committee, including any limits on such authority imposed by the investment committee in its discretion and the right of the investment committee to revoke such authority at any time. The Reporting Person disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein, if any. ( 4 )These shares shall vest in full on the earlier to occur of (a) the first anniversary of the grant date or (b) the date of the next annual meeting of stockholders following the grant date, subject to the Reporting Person's continued service on the Issuer's board of directors.

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).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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