On June 22, 2025 Exelixis, Inc. (Nasdaq: EXEL) reported 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) (Press release, Exelixis, JUN 22, 2025, View Source [SID1234654040]). 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).
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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.
About Zanzalintinib
Zanzalintinib is a third-generation oral tyrosine kinase inhibitor that inhibits the activity of receptor tyrosine kinases implicated in cancer growth and spread, including VEGF receptors, MET, AXL and MER. These receptor tyrosine kinases are involved in both normal cellular function and in pathologic processes such as oncogenesis, metastasis, tumor angiogenesis and resistance to multiple therapies, including immune checkpoint inhibitors. With zanzalintinib, Exelixis sought to build upon its extensive experience with the target profile of cabozantinib, the company’s flagship medicine, while improving key characteristics, including pharmacokinetic half-life. Zanzalintinib is currently being developed for the treatment of advanced solid tumors, including colorectal cancer, kidney cancer, head and neck cancer and neuroendocrine tumors.
Zanzalintinib is an investigational agent that is not approved for any use and is the subject of ongoing clinical trials.
About CRC
CRC is the third most common cancer and the second leading cause of cancer-related deaths in the U.S.1 Approximately 154,000 new cases will be diagnosed in the U.S. with around 53,000 expected deaths from the disease in 2025.1 CRC is most frequently diagnosed among people aged 65-74 and is more common in men and in people of non-Hispanic American Indian/Alaska Native descent.2 Nearly a quarter of CRC cases are diagnosed at the metastatic stage, at which point the five-year survival rate is just 16.2%.2 The liver is the most common site for CRC metastasis. Liver metastases significantly impact survival, with a median five-year survival rate of less than 14% when treated with palliative chemotherapy.