X0306 4 2022-07-19 0 0001501989 CytomX Therapeutics, Inc. CTMX 0001761518 Campoy Carlos C/O CYTOMX THERAPEUTICS, INC. 151 OYSTER POINT BLVD., STE. 400 SOUTH SAN FRANCISCO CA 94080 0 1 0 0 Chief Financial Officer Common Stock 2022-07-19 4 A 0 15000 0 A 43921 D Common Stock 2022-07-20 4 S 0 3949 1.4224 D 39972 D Represents Performance Stock Units ("PSUs") initially granted on October 24, 2021 that were subject to a performance-based vesting condition. The first milestone vesting condition was determined to be satisfied upon which 50% of the PSUs vested. Includes 22,500 restricted stock units. The shares were sold solely to satisfy tax or other government withholding obligations in connection with the vesting of shares subject to a PSU of the Issuer. /s/ Lloyd Rowland, as Attorney-in-Fact for Carlos Campoy 2022-07-21