Exelixis (Nasdaq: EXEL), based in Alameda, California, and Merck announced a clinical development collaboration to evaluate zanzalintinib in combination with Keytruda Qlex (pembrolizumab and berahyaluronidase alfa-pmph) in the STELLAR-316 trial, a planned Phase III pivotal study in patients with resected stage II/III colorectal cancer who test positive for molecular residual disease. Exelixis will sponsor the STELLAR-316 trial colorectal cancer program, with Merck supplying its subcutaneous anti-PD-1 therapy for use in the combination arm. Financial terms were not disclosed.
Asset profile: zanzalintinib
Zanzalintinib is an oral kinase inhibitor targeting the TAM kinases — TYRO3, AXL, and MER — along with MET and VEGF receptors. Exelixis is advancing the compound across multiple tumor types, including clear cell and non-clear cell renal cell carcinoma, neuroendocrine tumors, meningioma, lung cancer, and castration-resistant prostate cancer, in addition to colorectal cancer. In February 2026, the US FDA accepted an Exelixis new drug application for zanzalintinib in combination with atezolizumab (Tecentriq) for previously treated metastatic colorectal cancer, assigning a PDUFA target action date of December 3, 2026.
Keytruda Qlex is a subcutaneous formulation of pembrolizumab enabled by berahyaluronidase alfa-pmph, which facilitates subcutaneous delivery of the anti-PD-1 antibody. The product is distinct from the established intravenous pembrolizumab formulation and has received US FDA approval in at least one separate oncology indication. Its use in STELLAR-316 marks an extension of the subcutaneous anti-PD-1 therapy into a combination investigational setting with a next-generation tyrosine kinase inhibitor.
STELLAR-316 trial CRC design
STELLAR-316 will enroll patients with resected stage II/III colorectal cancer who, following definitive therapy, have tested positive for molecular residual disease and show no radiographic evidence of disease. The trial will evaluate zanzalintinib both with and without Keytruda Qlex, with disease-free survival as the primary endpoint. Circulating tumor DNA clearance is among the key secondary endpoints. Exelixis expects to initiate the STELLAR-316 trial colorectal cancer program in mid-2026.