CytomX reported expansion‑cohort data from a Phase 1 study of Varseta‑M, a ‘masked’ conditionally activated antibody‑drug conjugate targeting EpCAM, showing objective response rates of 20–32% at higher doses and median progression‑free survival of about 6.8–7.1 months in heavily pretreated metastatic colorectal cancer patients. The company said diarrhea was the most frequent treatment‑related adverse event but generally manageable with prophylaxis adjustments. CytomX plans to present additional data at upcoming meetings and to engage the FDA on a monotherapy development pathway in advanced CRC. One‑sentence clarification: a masked ADC uses tumor‑specific activation to widen the therapeutic window by limiting toxicity in normal tissues expressing the same antigen. Why it matters: these data validate conditional ADC strategies against hard‑to‑drug targets like EpCAM and could revive investor and partner interest after previous corporate strategic shifts away from ADCs.