Rachael Lester - 20 Oct 2025 Form 4 Insider Report for CytomX Therapeutics, Inc. (CTMX)

Role: Chief Business Officer
Signature: /s/ Christopher Ogden, as Attorney-in-Fact for Rachael Lester
Issuer symbol: CTMX
Transactions as of: 20 Oct 2025
Net transactions value: $0
Form type: 4
Filing time: 29 Oct 2025, 16:50:51 UTC
Next filing: 04 Feb 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Lester Rachael	Chief Business Officer	C/O CYTOMX THERAPEUTICS, INC., 151 OYSTER POINT BLVD., SUITE 400, SOUTH SAN FRANCISCO	/s/ Christopher Ogden, as Attorney-in-Fact for Rachael Lester	29 Oct 2025	0002094324

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	CTMX	Stock Option (Right to Buy)	Award	$0	+650,000		$0.000000	650,000	20 Oct 2025	Common Stock	650,000	$3.74	Direct	F1

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	25% of the shares subject to the option vest on the one year anniversary measured from October 20, 2025 (the "Vesting Commencement Date"), and 1/48th of the shares will vest monthly thereafter, 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.

Content

25% of the shares subject to the option vest on the one year anniversary measured from October 20, 2025 (the "Vesting Commencement Date"), and 1/48th of the shares will vest monthly thereafter, 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.