CytomX Therapeutics Q1 Earnings Call Highlights

Key Points

• Varseta‑M dose optimization is complete (40 patients in the optimization cohort; 113 total in Phase 1) after reporting confirmed ORRs of 20–32% and ~7 months median PFS, and CytomX aims to start a registrational late‑line CRC study in the first half of 2027 with a broader data and early OS update expected in H2 2026.
• The company is focused on managing GI toxicity—using upfront loperamide and budesonide to target grade ≥3 diarrhea in the 10–20% range—and is advancing combination programs, including Varseta‑M + bevacizumab (initial data expected H1 2027) and a chemotherapy combo planned to start in H2 2026, plus expansion into other EpCAM tumors.
• CytomX closed March with $346.7 million in cash (runway to at least H2 2028) and will prioritize capital toward Varseta‑M; separately, masked interferon candidate CX‑801 is in dose escalation with initial clinical data targeted by year‑end 2026.

CytomX Therapeutics NASDAQ: CTMX executives highlighted progress across the company’s lead clinical programs and reviewed first-quarter 2026 financial results, emphasizing continued development momentum for its EpCAM-targeted antibody-drug conjugate Varseta-M and its masked interferon alpha-2b candidate CX-801.

Varseta-M: Dose optimization complete and registrational planning underway

Chief Executive Officer and Chairman Dr. Sean McCarthy said 2026 has started “very exciting[ly], driven by our excellent clinical progress with Varseta-M in late-line colorectal cancer.” McCarthy described Varseta-M as a “first-in-class EpCAM targeting antibody drug conjugate” enabled by CytomX’s Probody masking platform, and said it is “the only EpCAM-directed ADC in clinical development to our knowledge.”

McCarthy reiterated CytomX’s long-term ambition for Varseta-M in colorectal cancer (CRC), stating the company’s goal is for it to become “a core component of the standard of care, including in earlier line therapy.” He also pointed to plans to expand development into other EpCAM-expressing tumors with a longer-term goal of potential pan-tumor use.

Referencing an earlier Phase 1 update shared in March, McCarthy said CytomX reported confirmed overall response rates (ORR) “between 20% and 32%” in late-line metastatic CRC and “approximately 7 months of median progression-free survival.” He contrasted those data with currently available therapies in that setting, which he said offer ORR “only in the low single digits and just a few months of PFS.”

On next steps, McCarthy said the company is in dose optimization with a goal of entering a registrational study in late-line CRC in the first half of 2027. CytomX also disclosed that it has completed enrollment in its dose optimization cohorts: “40 total patients now enrolled across the 8.6 and 10 mg/kg doses,” bringing total Phase 1 enrollment to 113 patients.

Second-half Phase 1 update expected to include broader dataset and early OS look

During the Q&A, McCarthy said the second-half 2026 clinical update is expected to be “fairly substantial” and include data “across the entire study,” including the full 40-patient dose optimization cohort. He said CytomX expects to have “reasonable follow-up” for safety and efficacy, including “an initial estimate of PFS” for the optimization patients.

McCarthy also said CytomX intends to provide “a first look at OS” in the second-half update, noting that overall survival is anticipated to be the primary endpoint for a future registrational study. He added that CytomX is not selecting patients in its CRC study, calling an “all comer late-line CRC” approach a “huge competitive advantage.”

Later in the Q&A, McCarthy clarified expectations around the maturity of survival data, indicating OS from the optimization cohort itself may be “too early” given the recency of completed enrollment, but that CytomX anticipates having OS from the earlier escalation and expansion phases for the second-half update.

Safety management focus: diarrhea prophylaxis and real-world translation

McCarthy said CytomX was encouraged by preliminary dose optimization results previously shared in March suggesting updated patient management strategies could reduce high-grade diarrhea seen earlier in Phase 1 development. He said patients typically respond well to management and that discontinuation rates have been low.

Asked whether grade 3 or higher diarrhea remained near the initially disclosed rate, McCarthy said CytomX had “no new data today,” but reiterated that the company was encouraged by the earlier report showing a 10% rate in the first 20 optimization patients. He described CytomX’s goal as managing grade 3 diarrhea “into the 10%-20% range,” supported by an adverse event management approach including “upfront use of loperamide and budesonide.”

McCarthy also addressed whether prophylaxis could create implementation friction in broader use, saying CytomX does not expect challenges translating the strategy into community oncology settings, and framed the dose optimization work as intended to define an approach suitable for pivotal studies and eventual commercialization.

Combination strategy: bevacizumab and chemotherapy studies

McCarthy said CytomX is advancing Varseta-M into combinations to support potential earlier-line use in CRC. The company has initiated a combination study with bevacizumab, which McCarthy called a “foundational combination” given anti-VEGF antibodies’ extensive use in CRC across settings. CytomX expects initial clinical data for the Varseta-M plus bevacizumab combination by the first half of 2027.

He added that dosing in the bevacizumab combination will include both every-two-week and every-four-week schedules, aligning with bevacizumab’s clinical use. In response to a question about whether a formulation change was required, McCarthy said “there’s no real formulation work that needs to be done,” describing it as a scheduling adjustment from every three weeks to every two or four weeks to match bevacizumab use in two-week regimens.

CytomX also plans to begin a Phase 1/2 chemotherapy combination study in the second half of 2026 evaluating Varseta-M with bevacizumab, 5-fluorouracil, and leucovorin. In the Q&A, McCarthy said the company intends to evaluate the “Varseta-M plus chemo plus Bev combination,” and stated it does not view the ongoing Varseta-M plus bevacizumab data as “gating necessarily” to starting the chemotherapy combination work in the second half of 2026.

Separately, CytomX said it remains on track to begin Phase 1 expansion cohorts in additional EpCAM-expressing indications in the second half of 2026, with McCarthy noting the company is still working through prioritization and expects to provide more specifics later in the year.

CX-801: Dose escalation continues, with initial clinical data targeted by year-end

McCarthy also provided an update on CX-801, CytomX’s masked interferon alpha-2b program in Phase 1 for advanced checkpoint-refractory melanoma. He described the company’s aim for CX-801 to serve as a combination immunotherapy “centerpiece,” and pointed to single-digit response rates with approved standard-of-care options in PD-1 refractory melanoma.

McCarthy said the monotherapy dose escalation has advanced to the fourth dose level, which “exceeds the approved clinical dose of unmasked interferon alpha-2b,” and that CX-801 has been “well-tolerated to date.” Combination dose escalation with KEYTRUDA is enrolling at the third dose level. McCarthy said CytomX expects to share initial clinical data by the end of 2026.

Financial results: cash balance increased following March financing

Chief Financial Officer Chris Ogden said CytomX “kicked off 2026 from a position of strength,” citing encouraging Varseta-M data and a financing completed in March. Ogden said CytomX projects cash runway “to at least the second half of 2028,” noting the guidance excludes potential collaboration milestones or new business development.

As of March 31, 2026, CytomX reported $346.7 million in cash equivalents and investments, compared to $137.1 million as of Dec. 31, 2025.

Ogden reported total revenue of $10.3 million for the first quarter, down from $50.9 million in the first quarter of 2025. He attributed the decline primarily to completion of collaboration obligations in 2025 under partnerships with Bristol Myers Squibb and Amgen.

Operating expenses were $29.8 million, compared with $28.3 million in the year-ago quarter. Research and development (R&D) expenses were $19.2 million, up $0.4 million year over year, which Ogden said was primarily due to increased manufacturing activities for Varseta-M, partially offset by restructuring expense incurred in the first quarter of 2025. General and administrative (G&A) expenses were $10.6 million, compared to $9.4 million in the prior-year quarter, which Ogden noted included one-time restructuring expenses.

Ogden said CytomX expects capital allocation to be “highly focused on Varseta-M” in the near to medium term, and said current cash resources are expected to support advancing Varseta-M into a registrational study in late-line CRC and generating additional Varseta-M data in combinations and in indications beyond CRC.

About CytomX Therapeutics NASDAQ: CTMX

CytomX Therapeutics, Inc is a clinical-stage biopharmaceutical company focused on the discovery and development of next-generation therapeutics based on its proprietary Probody® platform. The company engineers masked antibody prodrugs that remain inactive in healthy tissue but are selectively activated in the tumor microenvironment. This approach is designed to enhance the safety and tolerability of antibody-based therapies, particularly those targeting immuno-oncology pathways.

At the core of CytomX's pipeline is Pacmilimab (CX-072), an anti–PD-L1 Probody therapeutic currently undergoing clinical evaluation for multiple solid tumor indications.

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