531 A Phase 1b multi-tumor cohort study of cabozantinib plus atezolizumab in advanced solid tumors: results of the triple-negative breast cancer, ovarian cancer, and endometrial cancer cohorts

Background Cabozantinib, a multiple receptor tyrosine kinase inhibitor, promotes an immune-permissive environment which might enhance the activity of immune checkpoint inhibitors. COSMIC-021 ( NCT03170960 ), a multicenter phase 1b study, is evaluating the combination of cabozantinib with atezolizumab in advanced solid tumors; here we present efficacy and safety results in patients with triple negative breast cancer (TNBC), ovarian cancer (OC),...