Background: The increasing use of IO agents in the treatment of urothelial cancer has revealed irAEs during therapy. We investigated whether there is an association between treatment-related irAEs and CO in urothelial cancer pts treated with IO. Methods: We performed a retrospective analysis of 67 urothelial cancer pts treated with PD-1/PD-L1 inhibitors at Winship Cancer Institute from 2015-2018. Overall survival (OS) and progression free survival (PFS) were calculated from first IO dose to date of death or hospice referral and clinical or radiographic progression, respectively. Objective response (OR) was defined as partial or complete response per RECISTv1.1. Treatment-related irAEs were determined from clinic notes. The univariate association between irAE and clinical outcomes was generated using chi-square test and Fisher’s exact test. Results: The median age was 70 and 79.1% were men. 41.8% of pts had received 2 or more prior lines of therapy. Nine pts (13.4%) experienced irAEs including infusion reactions, rashes, and joint pain. Median follow-up from date of first dose of IO was 15 months (95% CI: 11-18 months). The overall death rate for pts who experienced irAE was 0%, while it was 62% for pts who did not experience irAE (p<0.001) (Table). Conclusions: Experiencing irAEs was associated with lower death rate and progression rate and higher rate of OR in this cohort. These findings should be validated in a larger study. Univariate association of irAEs with CO.

*statistical significance at alpha < 0.05