X0508 4 2023-08-14 0 0001720580 Adicet Bio, Inc. ACET 0001886986 Aftab Blake C/O ADICET BIO, INC. 200 BERKELEY STREET, 19TH FLOOR BOSTON MA 02116 0 1 0 0 Chief Scientific Officer 0 Stock Option (Right to Buy) 15.93 2023-08-14 4 D 0 50000 0.00 D 2031-04-29 Common Stock 50000 0 D Stock Option (Right to Buy) 2.14 2023-08-14 4 A 0 50000 0.00 A 2031-04-29 Common Stock 50000 50000 D Stock Option (Right to Buy) 7.38 2023-08-14 4 D 0 56612 0.00 D 2031-10-11 Common Stock 56612 0 D Stock Option (Right to Buy) 2.14 2023-08-14 4 A 0 56612 0.00 A 2031-10-11 Common Stock 56612 56612 D Stock Option (Right to Buy) 15.52 2023-08-14 4 D 0 125000 0.00 D 2032-01-06 Common Stock 125000 0 D Stock Option (Right to Buy) 2.14 2023-08-14 4 A 0 125000 0.00 A 2032-01-06 Common Stock 125000 125000 D Stock Option (Right to Buy) 12.18 2023-08-14 4 D 0 60000 0.00 D 2032-05-09 Common Stock 60000 0 D Stock Option (Right to Buy) 2.14 2023-08-14 4 A 0 60000 0.00 A 2032-05-09 Common Stock 60000 60000 D Stock Option (Right to Buy) 9.05 2023-08-14 4 D 0 117200 0.00 D 2033-01-23 Common Stock 117200 0 D Stock Option (Right to Buy) 2.14 2023-08-14 4 A 0 117200 0.00 A 2033-01-23 Common Stock 117200 117200 D 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. A total of 60,000 shares subject to an employee stock option were granted to the Reporting Person on October 12, 2021, with 25% of the shares subject to this option vested and exercisable on April 5, 2022, and 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. The Reporting Person previously exercised 3,388 shares subject to this option. 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. 25% of the shares subject to this option vested and became exercisable on October 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. 25% of the shares subject to this option vested and became exercisable on January 7, 2023, 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. 25% of the shares subject to this option vested and became exercisable on April 29, 2023, 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. 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. /s/ Nick Harvey, Attorney-in-Fact 2023-08-16