Exelixis and Merck Collaborate on Phase 3 Trial for Colorectal Cancer Treatment
Wednesday, May 20, 2026
Exelixis has announced a clinical development collaboration with Merck for the Phase 3 STELLAR-316 pivotal trial in patients with colorectal cancer (CRC).
CRC remains one of the most common cancers and a major cause of cancer-related deaths in the United States. Around 159,000 new cases are expected to be diagnosed in 2026, with nearly 55,000 deaths linked to the disease. The condition is most commonly diagnosed in people aged between 65 and 74 years. Survival rates are significantly lower once the disease spreads to other organs, particularly the liver.
Zanzalintinib is an investigational oral kinase inhibitor targeting TAM kinases, MET and VEGF receptors, which are associated with tumour growth, metastasis, angiogenesis, drug resistance and immune evasion. The development programme for zanzalintinib includes ongoing and planned trials across several cancer types, including colorectal cancer, renal cell carcinoma and neuroendocrine tumours.
The study will evaluate the combination of KEYTRUDA QLEX™ (pembrolizumab and berahyaluronidase alfa-pmph) for subcutaneous administration with zanzalintinib in patients with resected stage II/III CRC. Under the agreement, Exelixis will sponsor the trial, while Merck will provide KEYTRUDA QLEX.
The STELLAR-316 trial is designed for patients who have undergone definitive treatment for stage II/III CRC, tested positive for molecular residual disease (MRD+) and show no radiographic evidence of disease. The study will assess zanzalintinib both with and without KEYTRUDA QLEX. The primary endpoint will be disease-free survival, while key secondary endpoints will include circulating tumour DNA clearance.
Earlier this year, Exelixis also entered a collaboration with Natera for the trial. Natera will provide its Signatera™ assay to identify MRD-positive patients eligible for enrolment. Exelixis expects to begin the STELLAR-316 study in mid-2026.
In February 2026, the U.S. Food and Drug Administration accepted Exelixis’ New Drug Application for zanzalintinib in combination with Tecentriq® for previously treated metastatic CRC patients. The FDA has set a target action date of December 3, 2026.
Source: exelixis.com
