Real-world (rw) treatment (tx) patterns and clinical outcomes in patients (pts) with locally advanced/metastatic urothelial carcinoma (la/mUC): Insights from The US Oncology Network electronic health record (EHR).

e16551 Background: Current standard-of-care first-line (1L) tx for la/mUC includes platinum-based chemotherapy (PBC) followed by avelumab 1L maintenance (1LM) in pts without disease progression or immuno-oncology (IO) monotherapy for platinum-ineligible pts. However, not all pts receive guideline-based care. This study examines rw tx patterns and overall survival (OS) in pts with la/mUC receiving 1L systemic tx in the US, post FDA approval of avelumab 1LM tx in June 2020. Methods: This retrospective study used The US Oncology Network (iKnowMed) EHR database. The study included adult (≥18 y) pts diagnosed with la/mUC who initiated 1L tx (index date) between Dec 1, 2019, and Sep 30, 2022. For OS, pts were followed from index date until Dec 31, 2022. Pt characteristics and tx patterns were assessed descriptively. Kaplan-Meier analyses from 1L or 1LM initiation were used to evaluate OS. Results: Of 1,072 pts with la/mUC who initiated 1L tx, median (range) age at diagnosis was 73 y (40-90+), 74.9% were male and 46.2% had ECOG PS 0-1. Median (range) follow-up time from index date was 7.6 mo (0.3-39.5). Pts received the following 1L tx: IO monotherapy, n=469 (43.8%), PBC only, n=400 (37.3%), PBC with avelumab 1LM, n=112 (10.4%), and other, n=91 (8.5%). Median (range) age was highest in pts treated with IO monotherapy: 77 y (44-90+). Second-line (2L) and third-line tx were administered to 372 (34.7%) and 106 (9.9%) pts, respectively. Overall, the most common 2L tx were IO monotherapy (51.6%) and enfortumab vedotin (EV) monotherapy (24.5%). After avelumab 1LM, 34.8% of pts received 2L tx; 74.4% of those received EV. Median (range) follow-up from avelumab 1LM start was 6.6 mo (0.0-29.0). Median (95% CI) OS from start of avelumab 1LM was 14.0 mo (10.8-23.2). Median (95% CI) OS calculated from start of 1L PBC for pts who had received cisplatin- or carboplatin-based PBC with avelumab 1LM was 20 mo (16.0-26.5) and 18.4 mo (11.8-not reached), respectively. Median (95% CI) OS from start of 1L PBC was 15.5 mo (12.5-28.7) for cisplatin-based tx only, 11.5 mo (8.7-16.9) for carboplatin-based tx only, and 13.8 mo (11.7-17.5) for IO monotherapy. Conclusions: In this rw study of 1L tx in pts with la/mUC in community oncology practices, we observed a large proportion of pts receiving IO monotherapy and these pts were also older than pts receiving other 1L tx. Data from previously published rw studies showed substantial use of IO monotherapy even among platinum-eligible pts, outlining an opportunity to improve outcomes in select pts currently receiving IO monotherapy. Outcomes further support avelumab 1LM as a standard of care for pts without progression on PBC. Follow-up time was short; future studies with longer follow-up are needed to further characterize clinical outcomes to optimize tx selection and sequencing in pts with la/mUC.