CytomX Therapeutics (CTMX) 12th Annual Cantor Fitzgerald Global Healthcare Conference summary

Platform and pipeline

• Masking technology is designed to improve the therapeutic window of antibodies, biologics and cytokines; two lead clinical programs demonstrate its application.

• Varseta-M, an EpCAM-targeting ADC with a topoisomerase-1 payload, is being developed initially in colorectal cancer (CRC); a first pivotal study is targeted for H1 2027.

• CX-801 is a masked interferon alfa-2b in a Phase I study in late-line, post-checkpoint melanoma; initial data are targeted for H1 2027.

• Expanded Regeneron collaboration brought a $37 million upfront payment, supporting financial capacity for pipeline execution.

Varseta-M efficacy and safety

• In fourth-line-or-later CRC, early Phase I data showed a 20%+ response rate; later updates reported 20%-30% ORR and a dose response across 7.2, 8.6 and 10 mg/kg Q3W cohorts.

• At 8.6 and 10 mg/kg, reported PFS was 6-7 months; the study includes patients previously treated with irinotecan.

• Safety observations included low hematologic toxicity, no ILD and no acute pancreatitis; grade 3 diarrhea is the principal safety signal under evaluation.

• Among 14 patients treated with budesonide in the database, 12 had at least a one-grade improvement in diarrhea; grade 3 diarrhea was 10% in the first 20 dose-optimization patients, an early result with limited follow-up.

• Optimization uses 8.6 and 10 mg/kg Q3W, upfront loperamide and budesonide, and adjusted ideal body weight dosing; target grade 3 diarrhea rate is 10%-20%.

Data and pivotal development

• By year-end 2026, an update is planned from the 113-patient Phase I study, including ORR, PFS and OS from escalation and expansion, plus ORR and PFS from dose optimization.

• Initial OS disclosure will cover the first 73 treated patients; optimization-cohort OS is expected later, and the dose decision will integrate modeling across patients.

• FDA discussions are planned around the pivotal population, comparator and dose, using exposure-safety and exposure-activity analyses in the context of Project Optimus; the goal is to communicate after FDA dialogue later in 2026.

• The working assumption is a randomized late-line CRC registrational study with an OS primary endpoint; fourth-line development is viewed as a potentially faster route, while third-line choice depends in part on OS data and trial power.

• Fourth-line addressable US population was estimated at 10,000-20,000 patients; treatment would not require selection by tumor target or clinical characteristics.