Sumanta K. Pal, MD, Professor in the Department of Medical Oncology & Therapeutics Research and Co-director of the Kidney Cancer Program at the City of Hope Comprehensive Cancer Center, discusses results from Cohorts 3, 4, and 5 of the COSMIC-021 study, which is evaluating cabozantinib plus atezolizumab in various solid tumors including urothelial carcinoma. These data were recently presented at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting.

Urothelial carcinoma (also called transitional cell carcinoma) is the most common cancer of the renal pelvis or ureter, accounting for approximately 90% of all upper urinary tract tumors. Urothelial carcinoma starts in the urothelium and usually starts in the renal pelvis rather than the ureter, though in some cases it may be found in both.

As Dr. Pal explains, the COSMIC-021 study is a phase 1b study evaluating cabozantinib plus atezolizumab in a variety of solid tumors. At ASCO 2022, Dr. Pal presented results from cohorts 3, 4, and 5 which studied the treatment regimen in urothelial carcinoma patients. Patients enrolled in Cohort 3 and 4 had no prior therapy and were cisplatin-based chemo ineligible or eligible, respectively. Cohort 5 enrolled patients were those with one prior immune checkpoint inhibitor and no prior vascular endothelial growth factor receptor tyrosine kinase inhibitor (VEGFR-TKI) therapy. The primary endpoint of the study is objective response rate (ORR). Secondary outcome measures included duration of response (DOS), progression free survival (PFS), and overall survival (OS).

Thirty patients each were enrolled in Cohorts 3 and 4, and 31 in Cohort 5. As of Nov 30, 2021, the median follow-up for Cohorts 3, 4, and 5 was 27.9, 19.1, and 32.9 months, respectively. The cabozantinib plus atezolizumab regimen demonstrated clinical benefit across all cohorts. ORR for the three cohorts were 20% (Cohort 3), 30% (Cohort 4), and 10% (Cohort 5). Median DOR was 7.1 months, NE, and 4.1 months, respectively. Median PFS was 5.6 months, 7.8 months, and 3.0 months, respectively. Median OS was 14.3 months, 13.5 months, and 8.2 months, respectively.

The most common treatment-related adverse events of any grade across the three cohorts were diarrhea, nausea, fatigue, and decreased appetite. 

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