The FDA granted Fast Track designation to CytomX Therapeutics’ varsetatug masetecan (Varseta-M; CX-2051) for relapsed/refractory metastatic colorectal cancer. The ADC targets EpCAM and uses a masked, conditionally activated Probody design intended to minimize systemic exposure until it reaches tumor microenvironments. Fast Track follows Phase 1 dose-expansion data from CTMX-2051-101 (NCT06265688), where confirmed objective response rate ranged from 6% to 32% across expansion doses. The median progression-free survival was reported around 5–7 months depending on dose level, and diarrhea was the most common treatment-related adverse event, including grade 3 events in a subset of patients. CytomX indicated it could initiate a potential registrational study in the first half of 2027, positioning Varseta-M for continued development in a setting with limited options after prior lines of therapy.