X0508 4 2025-11-06 0001501989 CytomX Therapeutics, Inc. CTMX 0001654058 McCarthy Sean A. C/O CYTOMX THERAPEUTICS, INC. 151 OYSTER POINT BLVD., STE. 400 SOUTH SAN FRANCISCO CA 94080 true true CEO true Class A Common Stock 2025-11-06 4 S 0 101793 4.5377 D 987891 D Class A Common Stock 93158 I See footnote The transactions reported herein were effected pursuant to the Reporting Person's Rule 10b5-1 trading plan, adopted on August 27, 2024. This transaction was executed in multiple trades at prices ranging from $4.50 to $4.62, inclusive. The price reported above reflects the weighted average sale price. The Reporting Person undertakes to provide upon request by the staff of the Securities and Exchange Commission, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate sale price. Includes 488,750 restricted stock units. Shares held by Sean A. McCarthy 2018 Trust, of which the Reporting Person is trustee. /s/ Christopher Ogden, as Attorney-in-Fact for Sean A. McCarthy 2025-11-10