Treatment (tx) characteristics of patients (pts) with locally advanced or metastatic urothelial cancer (mUC) receiving checkpoint inhibitor (CPI) monotherapy in a US clinical practice.

4526 Background: Approval of anti–PD-L1/anti–PD-1 CPI agents has changed the mUC tx landscape, but real-world (RW) tx patterns are not well described. Here, we describe pt characteristics, time on tx (TOT), tx-cycle distribution, relative dose intensity (RDI) and subsequent tx for pts receiving atezolizumab (atezo), nivolumab (nivo) or pembrolizumab (pembro) monotherapy. Methods: Pts diagnosed with mUC who completed atezo, nivo or pembro in the first-line (1L) or prior-platinum second-line and beyond (2L+) settings by April 30, 2018, were identified from the US-based Flatiron Health electronic health record–derived database. TOT was defined as time from first to last CPI administration + 1 cycle, tx cycles as number of CPI doses received during TOT and RDI as ratio of actual to planned dose per week to reflect any dose interruption. Results: RW data from pts receiving atezo, nivo and pembro were analyzed (Table). Up to 38% of pts had ECOG PS > 1. Median TOT ranged from 2.1-2.8 mo, with overlapping 95% CIs; mean TOT ranged from 2.7-4.1 mo. Over 50% of pts had ≤ 4 tx cycles. 21%-38% of pts did not have RDI within 95%-105% of the labeled dose. Most common subsequent txs were platinum-based chemotherapy combinations with gemcitabine or taxanes (post–1L CPI) and taxane monotherapy or other CPI monotherapy/combinations (post–2L+ CPI). Conclusions: Here, we present the largest analysis of RW CPI use in mUC to date. Overall, this unadjusted descriptive analysis showed relative comparability of pt and tx characteristics and TOT across CPI-treated groups. Insights into RW tx allow for an understanding of how clinical trial data translate to broader pt populations, including those with ECOG PS > 1, and may be useful for practitioners. [Table: see text]