UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): June 19, 2019

CYTOMX THERAPEUTICS, INC.

(Exact name of Registrant as Specified in Its Charter)

151 Oyster Point Boulevard, Suite 400

South San Francisco, CA 94080

(Address of principal executive offices, including Zip Code)

Registrant’s telephone number, including area code: (650) 515-3185

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instructions A.2. below):

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

CytomX Therapeutics, Inc. (the “Company”) held its 2019 Annual Meeting of Stockholders (the “Annual Meeting”) on June 19, 2019. On the April 22, 2019 record date, there were 45,311,464 shares of the Company’s common stock outstanding with each such share being entitled to one vote per share.

At the Annual Meeting, 38,541,136 shares of the Company’s common stock were voted in person or by proxy for the four proposals set forth below, each of which is described in the Company’s Definitive Proxy Statement on Schedule 14A filed with the U.S. Securities and Exchange Commission on April 26, 2019.

Proposal 1. The Company’s stockholders elected the Class I director nominees below to the Company’s Board of Directors to hold office until the 2022 Annual Meeting of Stockholders and until their respective successors are duly elected and qualified, or the earlier of their death, resignation or removal.

Proposal 2. The Company’s stockholders ratified the selection of Ernst & Young LLP as the independent registered public accounting firm of the Company for its fiscal year ending December 31, 2019.

As a routine proposal under applicable rules, no broker non-votes were recorded in connection with this proposal.

Proposal 3. The approval, on a non-binding, advisory basis, of the compensation of the Company’s named executive officers:

Proposal 4. The non-binding, advisory vote regarding the frequency of future advisory votes by stockholders on the compensation of the Company’s named executive officers:

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.