CTMX

• Leadership & Team Updates: Welcome Rachael Lester as new Chief Business Officer, bringing strategic planning and business development experience to support the company's transition to commercial stage. CytomX's core mission is to develop innovative cancer treatments that are more effective than current standard of care, leveraging its proprietary ProBody masked therapeutic platform that selectively targets tumor tissue to spare healthy tissue and reduce toxicities.
• CX2051 (EPCAM-directed ProBody ADC for colorectal cancer (CRC)): CX2051 is the first and only EPCAM-directed ADC in clinical development, designed to address the large unmet need in metastatic CRC, where 5-year survival is just 13% and existing systemic EPCAM therapies failed due to normal tissue toxicity. Positive interim Phase 1 data (reported May 2025) showed robust clinical activity: confirmed objective responses or disease control in nearly all patients, preliminary median progression-free survival (PFS) of 5.8 months (compared to 2-3 months for current late-line treatments), activity across patient subgroups including liver metastases and KRAS mutations, and a favorable safety profile with no pancreatitis or liver toxicity that limited prior EPCAM therapies. The most common adverse event is diarrhea, a known side effect of topoisomerase I inhibitor-based therapies, which the company is actively focused on managing. By Q3 2025, the three planned dose expansion cohorts (7.2 mg/kg, 8.6 mg/kg, 10 mg/kg) reached their initial enrollment targets of ~20 patients each. Total enrollment in the Phase 1 study is now expected to reach ~100 patients ahead of the Q1 2026 data readout. CX2051 has potential as a pan-CRC therapy with additional opportunity across other EPCAM-expressing solid tumors, with updates on non-CRC indications planned for 2026.
• CX801 (masked interferon alpha 2B for advanced melanoma): CX801 is a masked dual-domain interferon program being developed in combination with Keytruda for advanced melanoma, designed to restore the potent anti-tumor activity of interferon while reducing systemic toxicity. Initial biomarker data to be presented at CITSE includes data from 5 monotherapy-treated patients, showing consistent interferon signaling activation in the tumor microenvironment, T cell activation, and preferential tumor activity with stable systemic chemokine levels. Monotherapy dose escalation has reached the fourth dose level, exceeding the approved clinical dose of unmasked interferon alpha 2B, confirming the masking technology works as intended. Combination dosing with Keytruda initiated in May 2025, with initial combination data expected by the end of 2026.
• Pipeline and Collaborations: A new preclinical program, CX908 (a masked T-cell engager targeting CDH3/P-cadherin), will be presented at CITSE, demonstrating that masking can widen the therapeutic window for T-cell engager modalities. The company continues ongoing collaboration work with Astellas and Regeneron in T-cell engagers and bispecifics.

• Cash runway: Current cash balance is projected to fund operations through at least the second quarter of 2027. This guidance does not include potential future milestone payments from existing collaborations or new business development activity.
• CX2051 Milestones: A full Phase 1 data update is expected in Q1 2026, which will inform dose selection for future studies and registrational path planning in line with FDA Project Optimus requirements. A Phase 1b combination study with Bevacizumab (a standard-of-care anti-VEGF therapy for CRC) is expected to initiate in Q1 2026. Updates on development plans for non-CRC indications for CX2051 are expected in 2026.
• CX801 Milestones: Initial clinical data for the CX801 + Keytruda combination is expected by the end of 2026.
• Capital Allocation: Advancing CX2051 to potential approval is the company's top capital allocation priority for 2026, with disciplined capital allocation focused on delivering key milestones for CX2051 and CX801.

CytomX is a clinical-stage biotech focused on oncology therapeutics, with no reported segment breakdown of revenue in this call. Total company revenue for Q3 2025 was $6 million, a sharp decrease from $33.4 million in Q3 2024, driven by completed performance obligations under the Bristol-Myers Squibb collaboration. Total operating expenses for Q3 2025 were $21.7 million, down from $29.3 million in Q3 2024. Research and development (R&D) expenses were $15.3 million, a $6.1 million decrease year-over-year, primarily due to lower expenses for the CX904 program and reduced general research costs. General and administrative (G&A) expenses were $6.4 million, a $1.5 million decrease year-over-year, driven by lower personnel, patent, and legal costs. As of September 30, 2025, CytomX held $143.6 million in cash, cash equivalents, and investments, down from $158.1 million at the end of Q2 2025.

• Forward-looking statements related to trial results, development timelines, and regulatory approvals are inherently uncertain, as clinical outcomes and regulatory feedback are outside of the company's control. Diarrhea is a common adverse event for CX2051 that requires ongoing management and protocol refinement, which could impact the drug's clinical profile and development path. Successfully demonstrating efficacy and safety sufficient for regulatory approval is not guaranteed, even with positive initial Phase 1 data. The cash runway projection excludes potential future funding needs from new initiatives or unexpected trial costs, requiring potential additional financing to extend operations beyond 2027. The competitive landscape for CRC treatment is evolving, with multiple investigational programs in late-stage development, creating market and clinical competition.

Q: What expectations should investors have for ORR and PFS at the Q1 2026 CX2051 readout, and will data be broken out by dose to support dose selection? / A: Initial data from the expansion dose levels already showed a 28% confirmed response rate, which is substantially higher than the single-digit ORR for current late-line standard of care, with a preliminary 5.8-month PFS compared to the current 2-3 month standard. Management expects the larger mature dataset will continue to show strong performance, and the Q1 2026 update will break out all efficacy and safety data by dose to support selection for Phase 2/3 studies.

Q: What is driving strong CX2051 enrollment, how is diarrhea prophylaxis progressing, and what are your thoughts on competing recent ESMO CRC data? / A: Rapid enrollment is driven by high investigator and patient interest in the program, following the positive May 2025 data readout. Prophylactic loperamide for diarrhea was implemented early in the expansion phase with investigator discretion for use, and the company is actively refining adverse event management protocols, with more data expected in 2026. Management noted that increased innovation in CRC is positive, and recent competitor data did not change their outlook for CX2051.

Q: What is the strategy for the CX2051 + Bevacizumab combination, and what line of therapy will it target? / A: The Phase 1b combination study will initiate in Q1 2026, starting with testing a small number of CX2051 doses to evaluate safety and activity. The long-term goal of the combination is to eventually move into second-line CRC therapy, with further trial design details to be determined after monotherapy data matures.

Q: What is your current regulatory strategy for CX2051 monotherapy, what line of therapy will you target for registrational development? / A: All registrational trial designs remain on the table. Early data already suggests CX2051 can outperform standard of care in fourth-line CRC. For third-line, where current standard of care has a ~5.5 month PFS, the mature PFS data from the Q1 2026 readout will clarify how competitive CX2051 can be in that setting before a final registrational path is selected.