CytomX Therapeutics Announces Business Update and Company Milestones for 2026

- CX-2051 (varsetatug masetecan) Phase 1 Colorectal Cancer expansion data on track for Q1 2026 -

- Varsetatug masetecan (“Varseta-M”) Phase 1 combination study with bevacizumab in Colorectal Cancer to start in Q1 2026 with initial data expected by 1H 2027 -

- Initial CX-801 Masked Interferon-alpha-2b Phase 1 combination data with KEYTRUDA^® (pembrolizumab) in melanoma expected by the end of 2026 -

- Company to present at 44th Annual JP Morgan Healthcare Conference on January 14th -

SOUTH SAN FRANCISCO, Calif., Jan. 08, 2026 (GLOBE NEWSWIRE) -- CytomX Therapeutics, Inc. (Nasdaq: CTMX), a leader in the field of masked, conditionally activated biologics, today announced a business update and anticipated milestones for 2026.

“We are excited to build on our transformational progress at CytomX with Varseta-M and will be focused on advancing this novel, potential first-in-class ADC towards a registrational study in late-line CRC. Varseta-M was specifically designed to address a broad, unselected CRC patient population based on the universally high and uniform expression of EpCAM. The promising initial clinical activity we have presented to date in Phase 1 dose escalation underscore this potential. We look forward to providing CRC Phase 1 expansion data later this quarter,” said Sean McCarthy, D.Phil., chief executive officer and chairman of CytomX.

Dr. McCarthy continued, “Given our highly encouraging start in late line CRC we aim to move rapidly towards a potentially registrational trial and advance Varseta-M into earlier lines of CRC treatment to maximize impact in this area of high unmet medical need. We also plan to capitalize on our platform leadership by progressing our broader pipeline of PROBODY^® Therapeutics, including our masked interferon-alpha-2b program, CX-801, in combination with KEYTRUDA^® in advanced melanoma.”

Clinical Program Updates and 2026 Milestones:

Varsetatug masetecan (EpCAM PROBODY Topo-1 ADC, CX-2051)

• Varseta-M Phase 1 dose expansions across the 7.2 mg/kg, 8.6 mg/kg, and 10 mg/kg doses, administered every three weeks (Q3W) are ongoing with a focus on selecting a dose or doses for a potential registrational study in advanced CRC.
• Total Phase 1 study enrollment is projected to reach approximately 100 patients by the planned Varseta-M Phase 1 update in Q1 2026.
• The Company aims to align with the FDA in 2026 on a potential registrational study design for Varseta-M monotherapy in advanced CRC.
• A Phase 1 Varseta-M combination study with bevacizumab in CRC is expected to start in Q1 2026, data from which is intended to inform potential late-phase development in earlier lines of CRC.
• Initiation of Phase 1 expansion cohort(s) in additional indications is planned for 2H 2026.
  

CX-801 (PROBODY Interferon alpha-2b)

• The CX-801 Phase 1 study is ongoing with a focus in advanced melanoma. CX-801 monotherapy dose escalation has reached the fourth dose level.  
• CX-801 monotherapy has been well tolerated at dose levels exceeding the approved dose of unmasked IFNα2b.¹
• In May 2025, Phase 1 dose escalation of CX-801 in combination with KEYTRUDA^® was initiated. Dose escalation of CX-801 in combination with KEYTRUDA^® is currently enrolling the 2^nd dose level.
• CX-801 monotherapy biomarker data in advanced melanoma patients were presented at the 2025 Society of Immunotherapy of Cancer (SITC) Annual Meeting that support CX-801’s mechanism of action and the ongoing combination study with KEYTRUDA^® (pembrolizumab).
• Initial clinical data for CX-801 in combination with KEYTRUDA^® in advanced melanoma is anticipated by the end of 2026.
  

KEYTRUDA^® is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA

CytomX JP Morgan Healthcare Conference Presentation
Dr. Sean McCarthy will present at the JP Morgan Healthcare Conference on January 14, 2026, at 9 a.m. PST. Participants may access the live webcast of the conference call from the Events and Presentations page of CytomX’s website at https://ir.cytomx.com/events-and-presentations.

About CytomX Therapeutics
CytomX is a clinical-stage, oncology-focused biopharmaceutical company focused on developing novel conditionally activated, masked 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 varsetatug masetecan (formerly CX-2051) and CX-801. Varseta-M is a masked, conditionally activated ADC directed toward epithelial cell adhesion molecule (EpCAM), armed with a topoisomerase-1 inhibitor payload and was discovered in collaboration with ImmunoGen, now part of AbbVie. EpCAM is a highly expressed but previously undruggable tumor antigen due to expression on normal tissues. Varseta-M is designed to open a therapeutic window for this high potential target and deliver meaningful anti-cancer activity in solid tumors, including CRC. CX-801 is a masked 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 and projected cash runway. 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 varsetatug masetecan (formerly CX-2051) and CX-801, 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 varsetatug masetecan and CX-801 and the timing of initial and ongoing data availability for our clinical trials, including varsetatug masetecan and CX-801, 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; uncertainties around the Company’s ability to raise sufficient funds to carry out its planned research and development; 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, including initial varsetatug masetecan results, 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 varsetatug masetecan and CX-801; 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, including China and the European Union; and the risk that we may incur higher costs than expected for research and development or unexpected costs and expenses or may not obtain expected savings from our announced restructuring. 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 Quarterly Report on Form 10-Q filed with the SEC on November 6, 2025. 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. All other trademarks are the properties of their respective owners.

Company Contact:
Chris Ogden
SVP, Chief Financial Officer
[email protected]

Investor Contact:
Precision AQ (formerly Stern Investor Relations)
Stephanie Ascher
[email protected]

Media Contact:
Redhouse Communications
Teri Dahlman
[email protected]

¹ Merck & Co., Inc. (2018). Sylatron (peginterferon alfa-2b) prescribing information. U.S. Food and Drug Administration