Exelixis Stock Falls After Phase 3 Colorectal Cancer Trial Shows Mixed Results

Core Insights - Exelixis Inc. stock is experiencing a decline following the release of detailed results from the STELLAR-303 Phase 3 trial, which evaluated zanzalintinib in combination with Roche's Tecentriq against Bayer's Stivarga for metastatic colorectal cancer [1][6] Group 1: Trial Results - The STELLAR-303 trial met one of its dual primary endpoints, showing a 20% reduction in the risk of death in the intention-to-treat population at the final analysis [2] - At a median follow-up of 18 months, median overall survival was 10.9 months for the zanzalintinib and atezolizumab combination compared to 9.4 months for regorafenib [2] - The 12- and 24-month landmark overall survival estimates were 46% and 20% for the combination, versus 38% and 10% for regorafenib [4] Group 2: Additional Findings - An interim analysis indicated a trend favoring the combination with overall survival of 15.9 months compared to 12.8 months at a median follow-up of 16.8 months [5] - A trend for improvement in progression-free survival (PFS) was also observed, although statistical superiority cannot be claimed at this time due to the prespecified hierarchical testing strategy [5][6] - The trend for PFS improvement was consistent across subgroups [6]