Phase 1b trial of cabozantinib in combination with atezolizumab in patients with locally advanced or metastatic urothelial carcinoma (UC) or renal cell carcinoma (RCC).

TPS42Background: Cabozantinib (CABO) is an oral receptor tyrosine kinase inhibitor of MET, VEGFR, and TAM family receptors (TYRO3, AXL, and MER). It is approved for patients (pts) with RCC after prior therapy with antiangiogenic therapy, and has demonstrated clinical activity in UC. In clinical studies, CABO exposure increased circulating CD8+ T cells and reduced immune-suppressive monocytes and Tregs. In preclinical tumor models, CABO increased MHC class 1 expression on tumor cells and reduced myeloid-derived suppressor cells. CABO may facilitate an immune-permissive tumor environment and may enhance response to immune checkpoint inhibitors. Atezolizumab (ATEZO), an anti-PD-L1 mAb, is approved for: locally advanced/metastatic UC in pts who are cisplatin-ineligible or have disease progression during/following platinum-containing chemo; pts with metastatic NSCLC and disease progression during/following platinum-containing chemo. We present the study design of an ongoing phase 1b study combining CABO with A...