Intra-patient heterogeneity in urothelial cancer (UC) circulating tumor cells (CTC) and PDL1 expression to identify biomarkers of response and new therapeutic targets: A pilot study.

4537Background: Recent use of immune checkpoint inhibitors (CI) has improved overall survival (OS) in a subset of patients (pts) with metastatic UC. Intra-patient tumoral heterogeneity and epitheli...