Sec Form 4 Filing - Healey Don @ Adicet Bio, Inc. - 2023-08-14

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 Healey Don 2. Issuer Name and Ticker or Trading Symbol Adicet Bio, Inc. [ ACET] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Technology Officer (Last) (First) (Middle) C/O ADICET BIO, INC., 200 BERKELEY STREET, 19TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 08/14/2023 (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

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) $ 13.27 08/14/2023 D( 1 ) 70,000 ( 2 ) 01/12/2031 Common Stock 70,000 $ 0 ( 1 ) 0 D Stock Option (Right to Buy) $ 2.14 ( 3 ) 08/14/2023 A( 1 ) 70,000 ( 2 ) 01/12/2031 Common Stock 70,000 $ 0 ( 1 ) 70,000 D Stock Option (Right to Buy) $ 16.82 08/14/2023 D( 1 ) 30,400 ( 4 ) 02/11/2031 Common Stock 30,400 $ 0 ( 1 ) 0 D Stock Option (Right to Buy) $ 2.14 ( 3 ) 08/14/2023 A( 1 ) 30,400 ( 4 ) 02/11/2031 Common Stock 30,400 $ 0 ( 1 ) 30,400 D Stock Option (Right to Buy) $ 15.52 08/14/2023 D( 1 ) 125,000 ( 5 ) 01/06/2032 Common Stock 125,000 $ 0 ( 1 ) 0 D Stock Option (Right to Buy) $ 2.14 ( 3 ) 08/14/2023 A( 1 ) 125,000 ( 5 ) 01/06/2032 Common Stock 125,000 $ 0 ( 1 ) 125,000 D Stock Option (Right to Buy) $ 9.05 08/14/2023 D( 1 ) 117,200 ( 6 ) 01/23/2033 Common Stock 117,200 $ 0 ( 1 ) 0 D Stock Option (Right to Buy) $ 2.14 ( 3 ) 08/14/2023 A( 1 ) 117,200 ( 6 ) 01/23/2033 Common Stock 117,200 $ 0 ( 1 ) 117,200 D Stock Option (Right to Buy) $ 2.14 08/14/2023 A 149,944 ( 7 ) 08/13/2033 Common Stock 149,944 $ 0 149,944 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Healey Don C/O ADICET BIO, INC. 200 BERKELEY STREET, 19TH FLOOR BOSTON, MA02116 Chief Technology Officer Signatures /s/ Nick Harvey, Attorney-in-Fact 08/16/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On August 8, 2023, the Issuer's Board of Directors approved an option repricing (the "Repricing"), effective as of August 14, 2023 (the "Effective Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable. ( 2 )25% of the shares subject to this option vested and became exercisable on January 13, 2022, with the remaining 75% vesting in thirty-six (36) equal monthly installments thereafter, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date. ( 3 )The exercise price of the option is $2.14 per share, representing the fair market value per share of the Issuer's Common Stock on the Effective Date; provided that the repriced option will revert to its original exercise price if, prior to the first anniversary of the Effective Date, (a) the Reporting Person's employment is terminated by the Issuer with cause or by the Reporting Person or (b) the option is exercised. ( 4 )25% of the shares subject to this option vested and became exercisable on February 12, 2022, with the remaining 75% vesting in thirty-six (36) equal monthly installments thereafter, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date. ( 5 )The shares subject to this option shall vest in forty-eight (48) equal installments on each monthly anniversary following January 7, 2022, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date. ( 6 )The shares subject to this option shall vest in forty-eight (48) equal installments on each monthly anniversary following January 24, 2023, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date. ( 7 )Prior to August 14, 2024, no shares shall be vested or exercisable under this option. Effective as of August 14, 2024, the following vesting schedule shall apply: 25% of the shares shall have vested and become exercisable on October 27, 2021, with the remaining 75% vesting in thirty-six (36) equal installments on each monthly anniversary following October 27, 2021, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date. This option was issued to the Reporting Person because his previously awarded option granted under Nasdaq Listing Rule 5635(c)(4) is not eligible for repricing.

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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