CytomX Therapeutics Announces First Patient Dosed with CX-2051, a Conditionally Activated EpCAM-Directed ADC, in a Phase 1 Study in Patients with Advanced Solid Tumors

SOUTH SAN FRANCISCO, Calif., April 08, 2024 (GLOBE NEWSWIRE) -- CytomX Therapeutics, Inc. (Nasdaq: CTMX), a leader in the field of conditionally activated, localized biologics, today announced the first patient has been dosed in a Phase 1 dose escalation study (NCT06265688) of CX-2051 in patients with advanced solid tumors. CX-2051 is a masked PROBODY® antibody drug conjugate (ADC) directed toward epithelial cell adhesion molecule (EpCAM), a cell-surface target that is highly expressed across many cancer types including colorectal, gastric, endometrial, and ovarian cancers. The cytotoxic payload utilized in CX-2051 is a derivative of camptothecin, a topoisomerase-1 inhibitor, a class of drug that has shown potent clinical anti-cancer activity and demonstrated significant clinical benefit as an approved ADC in multiple cancers. The CX-2051 Phase 1 dose escalation is designed to efficiently test the safety and preliminary anti-tumor activity of CX-2051, to provide initial clinical proof of concept to inform a potential decision to move into dose expansions in 2025.

“EpCAM is a high potential ADC target present at high levels on many solid cancers. CX-2051 has been optimized using our tailored masking strategies and possesses a potent cytotoxic payload ideally suited to specific EpCAM positive tumor types, including colorectal cancer. The successful initiation of the Phase 1 dose escalation study for CX-2051 is an important clinical milestone for CytomX as we continue to advance our multi-modality PROBODY therapeutic pipeline to address areas of significant unmet medical need,” said Wayne Chu, M.D., chief medical officer of CytomX Therapeutics.

About CytomX Therapeutics
CytomX is a clinical-stage, oncology-focused biopharmaceutical company focused on developing novel conditionally activated biologics designed to be localized to the tumor microenvironment. By pioneering a novel pipeline of localized biologics, powered by its PROBODY® therapeutic platform, CytomX’s vision is to create safer, more effective therapies for the treatment of cancer. CytomX’s robust and differentiated pipeline comprises therapeutic candidates across multiple treatment modalities including antibody-drug conjugates (“ADCs”), T-cell engagers, and immune modulators such as cytokines. CytomX’s clinical-stage pipeline includes CX-904, CX-2051 and CX-801. CX-904 is a conditionally activated T-cell-engaging bispecific antibody targeting the epidermal growth factor receptor (EGFR) on tumor cells and the CD3 receptor on T cells. CX-904 is partnered with Amgen in a global co-development alliance. CX-2051 is a conditionally activated ADC directed toward epithelial cell adhesion molecule, EpCAM, with potential applicability across multiple EpCAM-expressing epithelial cancers. CX-2051 was discovered in collaboration with Immunogen, now part of AbbVie. CX-801 is an interferon alpha-2b PROBODY® cytokine with broad potential applicability in traditionally immuno-oncology sensitive as well as insensitive (cold) tumors. CytomX has established strategic collaborations with multiple leaders in oncology, including Amgen, Astellas, Bristol Myers Squibb, Regeneron and Moderna. For more information about CytomX and how it is working to make conditionally activated treatments the new standard-of-care in the fight against cancer, visit www.cytomx.com and follow us on LinkedIn and X (formerly Twitter).

CytomX Therapeutics Forward-Looking Statements
This press release includes forward-looking statements. Such forward-looking statements involve known and unknown risks, uncertainties and other important factors that are difficult to predict, may be beyond our control, and may cause the actual results, performance, or achievements to be materially different from any future results, performance or achievements expressed or implied in such statements, including those related to the future potential of partnerships or collaboration agreements. Accordingly, you should not rely on any of these forward-looking statements, including those relating to the potential benefits, safety and efficacy or progress of CytomX’s or any of its collaborative partners’ product candidates, including CX-2051, CX-801, and CX-904, the potential benefits or applications of CytomX’s PROBODY® therapeutic platform, CytomX’s or its collaborative partners’ ability to develop and advance product candidates into and successfully complete clinical trials, including the ongoing and planned clinical trials of CX-904, and the timing of the commencement of clinical trials or initial and ongoing data availability for CX-801 and CX-2051, and other development milestones. Risks and uncertainties that contribute to the uncertain nature of the forward-looking statements include: the unproven nature of CytomX’s novel PROBODY® therapeutic technology; CytomX’s clinical trial product candidates are in the initial stages of clinical development and its other product candidates are currently in preclinical development, and the process by which preclinical and clinical development could potentially lead to an approved product is long and subject to significant risks and uncertainties, including the possibility that the results of preclinical research and early clinical trials may not be predictive of future results; the possibility that CytomX’s clinical trials will not be successful; the possibility that current preclinical research may not result in additional product candidates; CytomX’s dependence on the success of CX-904, CX-801, and CX-2051; CytomX’s reliance on third parties for the manufacture of the Company’s product candidates; possible regulatory developments in the United States and foreign countries; and the risk that we may incur higher costs than expected for research and development or unexpected costs and expenses. Additional applicable risks and uncertainties include those relating to our preclinical research and development, clinical development, and other risks identified under the heading "Risk Factors" included in CytomX’s Annual Report on Form 10-K filed with the SEC on March 11, 2024. The forward-looking statements contained in this press release are based on information currently available to CytomX and speak only as of the date on which they are made. CytomX does not undertake and specifically disclaims any obligation to update any forward-looking statements, whether as a result of any new information, future events, changed circumstances or otherwise.

PROBODY is a U.S. registered trademark of CytomX Therapeutics, Inc.

Investor Contact:
Chris Ogden
SVP, Finance and Accounting
cogden@cytomx.com

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Stern Investor Relations
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