CytomX Therapeutics released Phase 1 expansion data showing its masked antibody‑drug conjugate Varseta‑M achieved 20–32% response rates in heavily pretreated colorectal cancer cohorts and extended progression‑free survival by several months at higher doses. The company said diarrhea was the main treatment‑related toxicity but remained manageable with prophylaxis adjustments and that it will discuss registrational paths with the FDA. Separately, Astellas notified CytomX it will discontinue a $1.6 billion collaboration on T‑cell engagers, ending a six‑year alliance. Astellas’ exit narrows CytomX’s partnership runway even as the ADC data rekindles investor interest in the company’s lead oncology programs; CytomX indicated it will evaluate strategic options to advance Varseta‑M.