CytomX reported positive dose‑expansion data from a Phase I trial of varsetatug masetecan (varseta‑M) in metastatic colorectal cancer, prompting sharp intraday stock moves. At the 10 mg/kg dose cohort, varseta‑M produced a 32% overall response rate and median progression‑free survival of 7.1 months, the company disclosed (NCT06265688). CEO Sean McCarthy described the results as encouraging on an earnings call. Investors cheered the data even as Astellas recently terminated a collaboration with CytomX; the stock jumped 75% intraday before retreating and then oscillating over subsequent sessions. Jefferies analyst Roger Song framed the asset as a multibillion‑dollar opportunity if the masked ADC can expand beyond 3L mCRC. Market participants will look for confirmatory data and clarity on registrational strategy for varseta‑M.