Effect of concurrent beta-blocker (BB) use in patients receiving immune checkpoint inhibitors for metastatic urothelial (mUC) and renal cell carcinomas (mRCC).

467Background: Stress-induced adrenergic signaling suppresses the immune system. A pre-clinical mouse model has shown that pharmacologic beta-blockade can stimulate CD8+ T-cell activity, and as a result improve efficacy of checkpoint inhibitors (CPI) to inhibit growth in solid tumors. Herein, we investigate the effect of BB on outcomes of patients receiving immunotherapy in mUC and mRCC. Methods: Using the Mount Sinai Genitourinary (GU) Cancer Biorepository, an IRB approved database containing all consented GU cancer patients seen between 2010-2018, we identified patients with either UC or RCC that have received CTLA-4 and/or PD-1/PD-L1 blockade. Patients who received only 1 dose of CPI were excluded from this analysis. A descriptive analysis was performed to assess clinical characteristics and treatment response. Overall Survival (OS) was calculated with Kaplan-Meier curves and cox proportional hazard models. Results: We identified 34 evaluable patients with mUC and 14 with mRCC that received CPI (Table)...