X0306 4 2022-02-04 0 0001662244 Cyteir Therapeutics, Inc. CYT 0001199637 THERO JOHN F 128 SPRING ST, BUILDING A, SUITE 510 LEXINGTON MA 02421 1 0 0 0 Stock Option (Right to Buy) 5.91 2022-02-04 4 A 0 28300 0.00 A 2032-02-04 Common Stock 28300 28300 D The shares of common stock underlying this stock option award vest as to one-third of the shares subject to the option on each of the first, second and third anniversaries of February 4, 2022, subject to the Reporting Person's continued service to the board of directors of the Issuer through the applicable vesting date. /s/ Andrew Gengos, Attorney-in-Fact 2022-02-07