On May 19, 2026 Exelixis, Inc. (Nasdaq: EXEL) reported that the company has entered into a clinical development collaboration with Merck, known as MSD outside of the United States and Canada, to supply KEYTRUDA QLEX (pembrolizumab and berahyaluronidase alfa-pmph) injection for subcutaneous administration in combination with zanzalintinib in STELLAR-316, a planned phase 3 pivotal trial in patients with resected stage II/III colorectal cancer (CRC). Under the terms of the clinical development collaboration with Merck, Exelixis is sponsoring the STELLAR-316 pivotal trial, and Merck will supply KEYTRUDA QLEX.
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"This collaboration with Merck for the STELLAR-316 trial reflects the continued progress of the zanzalintinib clinical development program and is an important step forward in our efforts to advance a potentially new treatment option that may help prevent or delay metastatic progression for patients with resected colorectal cancer," said Dana T. Aftab, Ph.D., Executive Vice President, Research and Development, Exelixis. "We look forward to initiating the clinical trial to evaluate this novel combination, with the goal of enhancing treatment strategies and meaningfully improving clinical outcomes for patients with this form of cancer who face a high risk of recurrence."
STELLAR-316 is a planned phase 3 pivotal trial that will evaluate zanzalintinib with and without KEYTRUDA QLEX in patients with resected stage II/III CRC who, following definitive therapy, have tested positive for molecular residual disease (MRD+) and have no radiographic evidence of disease. The primary endpoint of the trial will be disease-free survival, with key secondary endpoints including circulating tumor DNA clearance. In January 2026, Exelixis announced a collaboration with Natera, a global leader in cell-free DNA and precision medicine, for STELLAR-316. Natera will provide its Signatera assay to identify MRD+ patients for trial enrollment. Exelixis expects to initiate STELLAR-316 in mid-2026.
About CRC
CRC is the third most common cancer and a leading cause of cancer-related deaths in the U.S.1 Approximately 159,000 new cases will be diagnosed in the U.S. in 2026, with around 55,000 expected deaths from the disease.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 around just 15%.1,2 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.3
About Zanzalintinib
Zanzalintinib is a novel oral kinase inhibitor that inhibits the activity of the TAM kinases (TYRO3, AXL, MER), MET and VEGF receptors. These kinases play important roles in oncogenic processes, including tumor cell proliferation, metastasis, angiogenesis, drug resistance and evasion of antitumor immunity. The zanzalintinib development program includes a series of ongoing and planned pivotal trials to explore its therapeutic potential in CRC, clear cell and non-clear cell renal cell carcinoma, and neuroendocrine tumors, as well as earlier-stage trials in meningioma, lung cancer and castration-resistant prostate cancer.
In February 2026, Exelixis announced that the U.S. Food and Drug Administration (FDA) accepted the company’s New Drug Application for zanzalintinib, in combination with atezolizumab (Tecentriq), for the treatment of adult patients with metastatic CRC who have been previously treated with fluoropyrimidine-, oxaliplatin- and irinotecan-based chemotherapy, and, if RAS wild-type, an anti-epidermal growth factor receptor (EGFR) therapy. The FDA assigned a Prescription Drug User Fee Act target action date of December 3, 2026.
Zanzalintinib is an investigational agent that is not approved for any use and is the subject of ongoing clinical trials.
(Press release, Exelixis, MAY 19, 2026, https://ir.exelixis.com/news-releases/news-release-details/exelixis-announces-clinical-development-collaboration-merck [SID1234665868])