Results of Operations and Financial Condition. On November 5, 2026, CytomX Therapeutics, Inc., a Delaware corporation (the “Company”), issued a press release reporting its unaudited financial results as of and for the three and nine months ended September 30, 2026. A copy of the press release is furnished herewith as Exhibit 99.1. The information in

of this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this

Director — Charles Fuchs, M.D., M.P.H.: Dr. Charles Fuchs was appointed to the Board of Directors as a Class II director.

The filing describes amendments to equity incentive and employee stock purchase plans, not a management change.

Entry into a Material Definitive Agreement. CytomX Therapeutics, Inc. (the “Company”) previously entered into that certain Collaboration and License Agreement, effective November 16, 2022 (as amended, the “Agreement”), with Regeneron Pharmaceuticals, Inc. (“Regeneron”), providing for the collaboration on the creation of conditionally-activated investigational bispecific cancer therapies utilizing the Company’s Probody ® therapeutic platform and Regeneron’s Veloci-Bi ® bispecific antibody deve…

of this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this

Other Events. On March 17, 2026, CytomX Therapeutics, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Jefferies LLC, Piper Sandler & Co. and Cantor Fitzgerald & Co., as representatives of the several underwriters named therein (collectively, the “Underwriters”), in connection with the offering, issuance and sale by the Company of 45,990,567 shares of the Company’s common stock, $0.00001 par value per share (the “Common Stock”), at an offering pr…

of this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this

of this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this

of this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this

The filing details the amendment and restatement of equity incentive plans, which is a routine corporate action.

Other Events. On May 12, 2025, CytomX Therapeutics, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Jefferies LLC and Piper Sandler & Co., as representatives of the several underwriters named therein (collectively, the “Underwriters”), in connection with the offering, issuance and sale by the Company of 76,923,076 shares of the Company’s common stock, $0.00001 par value per share (the “Common Stock”), at an offering price of $1.30 per share, les…

of this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this

Other Events. CX-2051 Phase 1 Interim Data Summary in Advanced, Late-line Colorectal Cancer On May 12, 2025, the Company announced positive interim Phase 1 data for its EpCAM PROBODY ® ADC candidate, CX-2051 monotherapy in advanced, late-line metastatic colorectal cancer (“CRC”). The interim data are as of an April 7 th 2025 data cutoff from the ongoing CTMX-2051-101 Phase 1 study. The data encompassed certain results from 25 CRC patients treated with CX-2051 at 5 dose levels ranging from 2.4…

of this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing. On February 24, 2025, CytomX Therapeutics, Inc. (the “Company”) received a written notice from the staff (the “Staff”) of the Listing Qualifications Department of the Nasdaq Stock Market (“Nasdaq”), notifying the Company that, for the 30 consecutive business day period between January 8, 2025 and February 21, 2025 the Company’s common stock, $0.00001 par value per share (the “Common Stock”), h…

Senior Vice President, Chief Business Officer, and Head of Strategy — Jeffrey Landau: Mr. Jeffrey Landau's employment with CytomX Therapeutics, Inc. was terminated.

Costs Associated with Exit or Disposal Activities. On January 6, 2025, CytomX Therapeutics, Inc. (the “Company”) announced plans to restructure its business to streamline its organization and prioritize CX-2051 (EpCAM PROBODY® ADC) and its activities to support its research collaborations. Based on the revised focus and capital allocation priorities, CytomX will reduce its organizational headcount by approximately 40%. The workforce reduction will primarily impact staff in general and adminis…

of this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this

of this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this

Chief Financial Officer — Chris Ogden: Chris Ogden was promoted to Chief Financial Officer from his previous role as Senior Vice President, Finance and Accounting.

of this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this

Director — Zhen Su, M.D., M.B.A.: Dr. Zhen Su was appointed to the Board of Directors, filling a vacancy.

of this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this

of this Form 8-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities and Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this