X0306 5 2021-12-31 0 0 1 0001720580 Adicet Bio, Inc. ACET 0001823901 Jakobovits Aya C/O ADICET BIO, INC. 200 CLARENDON STREET, FLOOR 6 BOSTON MA 02116 1 0 0 0 Common Stock 2021-12-22 4 S 0 L 7000 16.0162 D 332552 I See Footnote Common Stock 2021-12-22 4 S 0 L 7000 16.0286 D 332553 I See Footnote Common Stock 2021-12-23 5 G 0 L 109488 0.00 D 0 I See Footnote Common Stock 2021-12-23 5 G 0 L 29905 0.00 A 138076 I See Footnote Common Stock 2021-12-23 5 G 0 L 39791 0.00 A 372343 I See Footnote Common Stock 2021-12-23 5 G 0 L 39792 0.00 A 372345 I See Footnote These sales were effected pursuant to Rule 10b5-1 trading plans previously adopted by the Reporting Person. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $15.46 to $16.34. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request. Shares held in a trust of which Dr. Jakobovits' spouse is the trustee and Dr. Jakobovits' daughter is the beneficiary. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $15.47 to $16.34. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request. Shares held in a trust of which Dr. Jakobovits' spouse is the trustee and Dr. Jakobovits' son is the beneficiary. Represents a gift of Common Stock made on December 23, 2021. Shares transferred from a grantor retained annuity trust ("GRAT") of which Dr. Jakobovits' spouse is the trustee and Dr. Jakobovits the sole annuitant and current beneficiary. Following this transaction, this GRAT was terminated. Shares held in a revocable trust of which Dr. Jakobovits and her spouse are co-trustees. The Form 4s filed by Dr. Jakobovits on May 14, 2021, May 20, 2021 and June 17, 2021 (the "Prior Filings") incorrectly allocated the shares between trusts over which Dr. Jakobovits has beneficial ownership. The aggregate number of shares beneficially owned as reported in Column 5 of Table I on each of the Prior Filings was correct. Following the transactions reported on this Form 5, the shares over which Dr. Jakobovits has beneficial ownership are held in three trusts: (i) a trust of which Dr. Jakobovits' spouse is the trustee and Dr. Jakobovits' daughter is the beneficiary, (ii) a trust of which Dr. Jakobovits' spouse is the trustee and Dr. Jakobovits' son is the beneficiary, and (ii) a revocable trust of which Dr. Jakobovits and her spouse are co-trustees. /s/ Nick Harvey, Attorney-in-Fact for Aya Jakobovits 2022-02-14