CytomX reported positive dose‑expansion data for varsetatug masetecan (varseta‑M) in metastatic colorectal cancer, delivering a 32% overall response rate and median progression‑free survival of 7.1 months at the 10 mg/kg dose. The Probody‑masked ADC targets EpCAM and carries a topoisomerase‑1 inhibitor payload; CytomX licensed the payload chemistry from ImmunoGen. CEO Sean McCarthy told analysts the company plans aggressive development in CRC and potential expansion into other high‑EpCAM tumors. Investors reacted violently: shares jumped 75% intra‑day on the results then reversed, illustrating market sensitivity to early oncology readouts and partnership shifts after Astellas terminated a prior collaboration.