X0306 4 2022-09-12 0 0001701108 Spero Therapeutics, Inc. SPRO 0001946366 HAMED KAMAL C/O SPERO THERAPEUTICS, INC. 675 MASSACHUSETTS AVENUE, 14TH FLOOR CAMBRIDGE MA 02139 0 1 0 0 Chief Medical Officer Common Stock 2022-09-12 4 A 0 210000 0.00 A 210000 D Consists of restricted stock units ("RSUs"). Each RSU represents the right to receive one share of common stock upon vesting. The RSUs vest in four equal annual installments beginning on September 12, 2023, subject to the Reporting Person's continued service through the applicable vesting date. /s/ Tamara Joseph. Attorney-in-Fact for Kamal Hamed 2022-09-14