AMENDMENT NO. 1 TO THE OPEN MARKET SALE AGREEMENT

Exhibit 1.3

AMENDMENT NO. 1 TO THE OPEN MARKET SALE AGREEMENT

March 4, 2022

XXXXXXXXX LLC

000 Xxxxxxx Xxxxxx

New York, New York 10022

Ladies and Gentlemen:

This Amendment No. 1 to the Open Market Sale Agreement (this “Amendment”) is entered into as of the date first written above by CytomX Therapeutics, Inc., a Delaware corporation (the “Company”), and Xxxxxxxxx LLC (the “Agent”), that are parties to that certain Open Market Sale Agreement, dated February 27, 2020 (the “Original Agreement”) relating to the offering of up to $75,000,000 of the Company’s Common Shares.

All capitalized terms not defined herein shall have the meanings ascribed to them in the Original Agreement.

The parties, intending to be legally bound, hereby amend the Original Agreement as follows:

1. Section 2(a) of the Original Agreement is hereby deleted in its entirety and replaced with the following:

Registration Statement. The Company has prepared and filed with the Commission a shelf registration statement on Form S-3, as amended by Amendment No. 1 to Form S-3 (File No. 333- 258510) that contains a base prospectus (the “Base Prospectus”). Such registration statement registers the issuance and sale by the Company of the Shares under the Securities Act. Except where the context otherwise requires, such registration statement, including any information deemed to be a part thereof pursuant to Rule 430B under the Securities Act, including all financial statements, exhibits and schedules thereto and all documents incorporated or deemed to be incorporated therein by reference pursuant to Item 12 of Form S-3 under the Securities Act as from time to time amended or supplemented, is herein referred to as the “Registration Statement,” and the Base Prospectus constituting a part of such registration statement(s), together with any prospectus supplement filed with the Commission pursuant to Rule 424(b) under the Securities Act relating to a particular issuance of the Shares, including all documents incorporated or deemed to be incorporated therein by reference pursuant to Item 12 of Form S-3 under the Securities Act, in each case, as from time to time amended or supplemented, is referred to herein as the “Prospectus,” except that if any revised prospectus is provided to the Agent by the Company for use in connection with the offering of the Shares that is not required to be filed by the Company pursuant to Rule 424(b) under the Securities Act, the term “Prospectus” shall refer to such revised prospectus from and after the time it is first provided to the Agent for such use. The Registration Statement at the time it originally became effective is herein called the “Original Registration Statement.” As used in this Agreement, the terms “amendment” or “supplement” when applied to the Registration Statement or the Prospectus shall be deemed to include the filing by the Company with the Commission of any document under the Exchange Act after the date hereof that is or is deemed to be incorporated therein by reference.

All references in this Agreement to financial statements and schedules and other information which is “contained,” “included” or “stated” in the Registration Statement or the Prospectus (and all other

references of like import) shall be deemed to mean and include all such financial statements and schedules and other information which is or is deemed to be incorporated by reference in or otherwise deemed under the Securities Act to be a part of or included in the Registration Statement or the Prospectus, as the case may be, as of any specified date; and all references in this Agreement to amendments or supplements to the Registration Statement or the Prospectus shall be deemed to mean and include, without limitation, the filing of any document under the Exchange Act which is or is deemed to be incorporated by reference in or otherwise deemed under the Securities Act to be a part of or included in the Registration Statement or the Prospectus, as the case may be, as of any specified date.

At the time the Registration Statement was originally declared effective and at the time the Company’s most recent annual report on Form 10-K was filed with the Commission, the Company met the then-applicable requirements for use of Form S-3 under the Securities Act. During the Agency Period, each time the Company files an annual report on Form 10-K the Company will meet the then-applicable requirements for use of Form S-3 under the Securities Act.

2. The definition of “Sanctioned Country” as defined in Section 2(kk) of the Original Agreement is hereby replaced with the following:

“Sanctioned Country” means, at any time, a country, region or territory which is itself the subject or target of any Sanctions (at the time of this Agreement, the so-called Donetsk People’s Republic, or any other Covered Region of Ukraine identified pursuant to Executive Order 14065, the Crimea Region of Ukraine, Cuba, Iran, North Korea and Syria).

3. All references in the Original Agreement to the “Agreement” shall mean the Original Agreement as amended by this Amendment; provided, however, that all references to “date of this Agreement” in the Original Agreement shall continue to refer to the date of the Original Agreement, unless amended otherwise herein and except with respect to the first paragraph of Section 2, Section 2(b) “Compliance with Registration Requirements,” and Section 8(a) “Press Release and Disclosure,” where references to “date of this Agreement” in the Original Agreement shall mean refer to each of the date of the Original Agreement and the date of this Amendment.

4. This Amendment shall be governed by and construed in accordance with the internal laws of the State of New York applicable to agreements made and to be performed in such state. Any legal suit, action or proceeding arising out of or based upon this Amendment or the transactions contemplated hereby or by the Original Agreement may be instituted in the federal courts of the United States of America located in the Borough of Manhattan in the City of New York or the courts of the State of New York in each case located in the Borough of Manhattan in the City of New York (collectively, the “Specified Courts”), and each party irrevocably submits to the exclusive jurisdiction (except for proceedings instituted in regard to the enforcement of a judgment of any such court, as to which such jurisdiction is non-exclusive) of such courts in any such suit, action or proceeding. Service of any process, summons, notice or document by mail to such party’s address set forth in the Original Agreement shall be effective service of process for any suit, action or other proceeding brought in any such court. The parties irrevocably and unconditionally waive any objection to the laying of venue of any suit, action or other proceeding in the Specified Courts and irrevocably and unconditionally waive and agree not to plead or claim in any such court that any such suit, action or other proceeding brought in any such court has been brought in an inconvenient forum.

5. This Amendment may be executed in any number of counterparts, each of which shall be deemed to be an original, but all such counterparts shall together constitute one and the same instrument. Delivery of an executed amendment by one party to the other may be made by facsimile, electronic mail or other transmission method as permitted by applicable law, and the parties hereto agree that any counterpart so delivered shall be deemed to have been duly and validly delivered and be valid and effective for all purposes. A party’s electronic signature (complying with the New York Electronic Signatures and Records Act (N.Y. State Tech. §§ 301-309), as amended from time to time, or other applicable law) of this Amendment shall have the same validity and effect as a signature affixed by the party’s hand.

If the foregoing correctly sets forth the understanding between the Company and the Agent, please so indicate in the space provided below for that purpose, whereupon this letter shall constitute a binding amendment to the Original Agreement between the Company and the Agent.

Very truly yours,
XXXXXXXXX LLC
By:		/s/ Xxxxxxx Xxxxxxx
Name:		Xxxxxxx Xxxxxxx
Title:		Managing Director
ACCEPTED as of the date first-above written:
CYTOMX THERAPEUTICS, INC.
By:		/s/ Xxxx X. XxXxxxxx
Name:		Xxxx X. XxXxxxxx, X. Xxxx.
Title:		Chief Executive Officer

[Signature Page to Amendment No. 1 to the Open Market Sale Agreement]