Exelixis Sees Stock Surge After Combo Therapy Shows Survival Advantage in Colorectal Cancer Trial

Shares of Exelixis Inc. $EXEL advanced 8.8% in early trading following interim findings from the STELLAR-303 Phase 3 study, which investigated a dual-therapy regimen for metastatic colorectal cancer (mCRC). The investigational compound zanzalintinib, used alongside the PD-L1 inhibitor atezolizumab, demonstrated a statistically meaningful improvement in overall survival versus regorafenib, a current second-line therapy.

Interim Data Underscore Survival Impact

In patients with previously treated mCRC, the combination therapy achieved one of the two primary endpoints, overall survival in the intent-to-treat (ITT) cohort. A pre-specified final analysis will now assess survival in patients without liver metastases. Importantly, the safety profile aligned with historical trends and revealed no emergent risks.

Implications for Exelixis’ Oncology Strategy

The outcome provides clinical validation for zanzalintinib as a viable component in Exelixis’ evolving oncology pipeline. With efficacy demonstrated against a high-benchmark comparator, the data enhance the compound’s potential in a competitive therapeutic segment. Dr. Amy Peterson, EVP of Product Development and Chief Medical Officer at Exelixis, described the milestone as a foundational achievement that supports the company’s commitment to advancing targeted therapies in solid tumors.

Market Response Reflects Confidence in Late-Stage Pipeline

The favorable survival signal triggered investor optimism, especially given the ongoing pressure across the biotech sector. While Cabozantinib (Cabometyx) remains the cornerstone of Exelixis’ commercial portfolio, the clinical progress of zanzalintinib suggests a diversification of revenue prospects in the medium term. Within the broader immuno-oncology space, dual-regimen approaches like zanzalintinib plus atezolizumab could reshape treatment strategies for hard-to-treat mCRC, particularly where tolerability and progression-free survival remain unmet needs.

Forward Momentum and Clinical Relevance

Pending the final analysis, Exelixis may explore regulatory engagement with health authorities. A positive outcome could position zanzalintinib as a competitive alternative to regorafenib, potentially offering superior efficacy with a manageable safety profile.

The results come at a time when combination regimens with checkpoint inhibitors are gaining ground in colorectal and other solid tumors. Zanzalintinib’s performance may also inform future trials in additional oncology settings.