Exelixis Announces Zanzalintinib in Combination with an Immune Checkpoint Inhibitor Improved Overall Survival in STELLAR-303 Phase 3 Pivotal Trial in Patients with Metastatic Colorectal Cancer

Exelixis, Inc. (Nasdaq: EXEL) today announced positive topline results from the STELLAR-303 phase 3 pivotal trial in which zanzalintinib in combination with atezolizumab (Tecentriq) demonstrated a statistically significant improvement in overall survival (OS) versus regorafenib in the intent-to-treat (ITT) population of patients with previously treated non-microsatellite instability (MSI)-high metastatic colorectal cancer (CRC). These topline findings are from the final analysis conducted by the Independent Data Monitoring Committee of one of the dual primary endpoints of the STELLAR-303 phase 3 trial. The trial will proceed to the planned final analysis for the other dual primary endpoint of OS in patients without liver metastases (non-liver metastases, NLM).

The safety profiles of zanzalintinib in combination with atezolizumab and of regorafenib were generally consistent with what has been previously observed, and no new safety signals were identified.

The ITT population consisted of all randomized patients, regardless of the presence of liver metastases. The NLM subgroup consisted of patients who did not have active liver metastases at baseline as determined by investigator assessment.

“The STELLAR-303 results, which showed a survival benefit with the combination of zanzalintinib and atezolizumab versus regorafenib across all randomized patients with previously treated metastatic colorectal cancer, marks an important first milestone for our zanzalintinib pivotal development program,” said Amy Peterson, M.D., Executive Vice President, Product Development & Medical Affairs, and Chief Medical Officer, Exelixis. “We look forward to discussing the findings with regulatory authorities and presenting the detailed results at an upcoming medical conference.”

Secondary endpoints of STELLAR-303 include progression-free survival, objective response rate and duration of response in the ITT population and in the NLM subgroup of patients. Exelixis plans to submit detailed results of STELLAR-303 for presentation at an upcoming medical conference.

About STELLAR-303
STELLAR-303 (NCT05425940) is a global, multicenter, randomized, phase 3, open-label study that randomized 901 patients 1:1 to either zanzalintinib (100 mg) in combination with atezolizumab or regorafenib. The study includes patients with previously treated non-MSI-high metastatic CRC. The dual primary endpoints of the study are OS in the ITT population and in the NLM subgroup of patients. Presence of liver metastases at baseline for all enrolled patients was determined by investigator assessment. Secondary endpoints include progression-free survival, objective response rate and duration of response in the ITT population and in the NLM subgroup of patients. More information about the trial is available at ClinicalTrials.gov.