Clinicopathologic and Genomic Characterization of PD-L1 Positive Urothelial Carcinomas.

In this study, a higher prevalence of TP53 and RB1 alterations and APOBEC mutational signatures in the PD-L1positive urothelial carcinoma disease subset and enrichment of FGFR3 alterations in the PD-L1negative disease subset were found. These data provide the basis for future investigation into the role of these genomic changes as positive and negative predictors of immunotherapy response. Also, differences wer seen in PD-L1 positivity based on the collection site of the sample, which can provide a framework for future clinical trial design and could influence sample selection for PD-L1 testing in patients with urothelial carcinoma when multiple samples are available.