X0306 4 2017-01-25 0 0001501989 CytomX Therapeutics, Inc. CTMX 0001579781 HUMPHREY RACHEL 343 OYSTER POINT BLVD. SUITE 100 SOUTH SAN FRANCISCO CA 94080 0 1 0 0 Chief Medical Officer Stock Option (right to buy) 11.94 2017-01-25 4 A 0 120000 0.00 A 2027-01-24 Common Stock 120000 120000 D 1/48th of the shares subject to the option vest on each monthly anniversary measured from January 1, 2017 (the "Vesting Commencement Date"), such that 100% of the shares subject to the option will be fully vested and exercisable on the fourth anniversary of the Vesting Commencement Date, subject to the Reporting Person's continued service to the Issuer through each such date. /s/ Cynthia J. Ladd, as Attorney-in-Fact for Rachel Humphrey 2017-01-27