SCHEDULE 13G 0001224962 XXXXXXXX LIVE Common Stock, $0.00001 par value per share 08/14/2025 0001501989 CytomX Therapeutics, Inc. 23284F105 151 Oyster Point Blvd., Suite 400 South San Francisco CA 94080 Rule 13d-1(c) Perceptive Advisors LLC DE 0 9680185 0 9680185 9680185 N 5.9 IA Joseph Edelman X1 0 9680185 0 9680185 9680185 N 5.9 IN Perceptive Life Sciences Master Fund, Ltd. E9 0 9680185 0 9680185 9680185 N 5.9 CO CytomX Therapeutics, Inc. 151 Oyster Point Blvd., Suite 400, South San Francisco, CA 94080 The names of the persons filing this report (collectively, the "Reporting Persons") with respect to shares of Common Stock, par value $0.00001 per share (the "Common Stock") of CytomX Therapeutics, Inc. (the "Issuer") are: Perceptive Advisors LLC ("Perceptive Advisors") Joseph Edelman ("Mr. Edelman") Perceptive Life Sciences Master Fund, Ltd. (the "Master Fund") The address of the principal business office of each of the Reporting Persons is: 51 Astor Place, 10th Floor New York, NY 10003 Perceptive Advisors is a Delaware limited liability company Mr. Edelman is a United States citizen The Master Fund is a Cayman Islands corporation Y The information required by this item with respect to each Reporting Person is set forth in Rows 5 through 9 and 11 of the cover pages to this Schedule 13G. The ownership percentages reported are based on 164,912,906 outstanding shares of Common Stock as of July 31, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on August 7, 2025. The Master Fund directly holds 9,680,185 shares of Common Stock. Perceptive Advisors serves as the investment manager to the Master Fund and may be deemed to beneficially own the securities directly held by the Master Fund. Mr. Edelman is the managing member of Perceptive Advisors and may be deemed to beneficially own the securities directly held by the Master Fund. Perceptive Advisors: 5.9% Mr. Edelman: 5.9% Master Fund: 5.9% Perceptive Advisors: 0 Mr. Edelman: 0 Master Fund: 0 Perceptive Advisors: 9,680,185 Mr. Edelman: 9,680,185 Master Fund: 9,680,185 Perceptive Advisors: 0 Mr. Edelman: 0 Master Fund: 0 Perceptive Advisors: 9,680,185 Mr. Edelman: 9,680,185 Master Fund: 9,680,185 Y Y Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. Perceptive Advisors LLC /s/ Joseph Edelman 08/21/2025 Joseph Edelman /s/ Joseph Edelman 08/21/2025 Perceptive Life Sciences Master Fund, Ltd. /s/ Joseph Edelman 08/21/2025