Globenewswire·2026-03-16 11:00Core Insights - CytomX Therapeutics announced positive Phase 1 expansion data for its EpCAM PROBODY® ADC, varsetatug masetecan (Varseta-M), in late-line metastatic colorectal cancer (CRC) [1][2] - The company plans to engage with the FDA regarding the registrational path for Varseta-M, aiming to improve treatment options for late-line CRC patients [2][3] Patient Characteristics - The study enrolled 93 patients with late-line metastatic CRC, with 60 patients in the Phase 1 expansion dose range [7] - Patients had a median of 3 prior lines of therapy, with 96% previously treated with irinotecan, and 76% had liver metastases [7] Efficacy Data - Confirmed response rates were 32% at 10 mg/kg and 20% at 8.6 mg/kg, with estimated progression-free survival (PFS) of 7.1 months and 6.8 months respectively [6][11] - Disease control rates were 84% to 90% across the expansion doses [9] Safety Profile - The safety profile was consistent with earlier data, with most treatment-related adverse events being Grade 1 or 2 [10] - The most common treatment-related adverse event was diarrhea, with a Grade 3 rate of 10% at the optimized doses [12] Future Plans - CytomX aims to align with the FDA on a potential registrational study design for Varseta-M in advanced CRC in 2026 [16] - A Phase 1 study evaluating Varseta-M in combination with bevacizumab has been initiated, with a Phase 1b/2 study expected to start by the end of 2026 [16]