Exelixis said it will file a US NDA for zanzalintinib after detailed Phase 3 Stellar‑303 results showed an overall survival benefit when combined with atezolizumab versus regorafenib in previously treated metastatic colorectal cancer. The company reported a 20% reduction in risk of death in the intent‑to‑treat population and plans a regulatory submission before year‑end. Investors reacted cautiously: Exelixis shares fell after clinicians and analysts parsed the magnitude of the survival gain and the safety profile. Company R&D head Dana Aftab framed the data as a potential new option for a hard‑to‑treat population, while analysts noted the benefit may fall short of some market expectations and that toxicity and comparative effectiveness versus existing regimens will shape uptake and regulatory review.