Exelixis Inc. (NASDAQ:EXEL) stock is trading lower on Monday after the company shared detailed results from the STELLAR-303 Phase 3 trial.
The trial evaluated zanzalintinib plus Roche Holdings AG’s (OTC:RHHBY) Tecentriq (atezolizumab) versus Bayer AG’s (OTC:BAYRY) Stivarga (regorafenib) for previously treated non-microsatellite instability (MSI)-high metastatic colorectal cancer (CRC).
In June, the company said the study met one of its dual primary endpoints, demonstrating a 20% reduction in the risk of death with the combination in the intention-to-treat (ITT) population at the final analysis.
At a median follow-up of 18.0 months, median overall survival in the ITT population was 10.9 months with zanzalintinib in combination with atezolizumab versus 9.4 months with regorafenib.
Also Read: Exelixis’ Zanzalintinib Combo Boosts Survival In Colorectal Cancer, Stock Soars
Overall survival is the length of time a person is alive from the start of a disease or treatment.
Detailed findings from the study were presented at the 2025 European Society for Medical Oncology.
An overall survival benefit with the combination was consistently observed across prespecified subgroups.
The 12- and 24-month landmark overall survival estimates were 46% and 20%, respectively, for the combination of zanzalintinib and atezolizumab, and 38% and 10%, respectively, for regorafenib.
Overall survival in patients without liver metastases (non-liver metastases, NLM), were immature at the data cutoff.
A prespecified interim analysis showed a trend in OS favoring the combination 15.9 months versus 12.8 months at a median follow-up of 16.8 months. The trial will proceed to the planned final analysis for this endpoint.
A trend for improvement in PFS with the combination was also observed in the ITT population. However, statistical superiority cannot be claimed at this time due to the prespecified hierarchical testing strategy. Investors are likely reacting to this update.
The trend for PFS improvement with zanzalintinib in combination with atezolizumab versus regorafenib was consistent across subgroups.
Price Action: EXEL stock is down 12.17% at $34.47 at the last check on Monday.
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