Real-world (rw) treatment (tx) patterns and overall survival (OS) in patients (pts) with locally advanced/metastatic urothelial carcinoma (la/mUC) treated with avelumab first-line maintenance (1LM): Updated results from the SPEAR Bladder II study.

393 Background: Avelumab 1LM tx is approved in the US for pts with la/mUC who do not have disease progression after platinum-based chemotherapy (PBC). The tx landscape is evolving due to the recent approvals of newer therapies for pts with la/mUC. This study examines rw tx patterns, tx sequencing post avelumab 1LM, and OS in pts with la/mUC who initiated 1L tx in the US community oncology setting. Methods: This retrospective cohort study used the US Oncology Network (iKnowMed) EHR database. The study included adult pts (≥18 years) with la/mUC initiating 1L tx (index date) between Dec 1, 2019, and Nov 30, 2023. Pts were censored for OS at their last contact date or the end of study period, Feb 28, 2024. Descriptive statistics were used to describe tx patterns. Kaplan-Meier analysis was used to evaluate OS from the start of 1LM or second-line (2L) enfortumab vedotin (EV) treatment post avelumab 1LM. Results: A total of 1,658 pts with la/mUC initiated 1L tx with a median (range) follow-up of 9.0 months (0.1-50.4). The median (range) age at diagnosis was 73 years (31-90+), 74.7% were male and 47.1% had ECOG performance status ≤1. The 1L therapies included: IO monotherapy (41.2%), PBC only (32.4%), PBC followed by avelumab 1LM (11.2%), and other tx (15.1%). Since the US FDA approval (June 30, 2020), the utilization of avelumab 1LM among 1L PBC users ranged from 25.0% to 32.9% in 2023. Median (range) follow-up from the start of avelumab 1LM was 9.1 months (0.5-42.2). During the study observation period, 44 pts (23.7%) remained on avelumab 1LM. Median (95% CI) OS from start of avelumab 1LM was 18.5 months (13.8-23.8). Among the overall study cohort, 598 (36.1%) and 196 pts (11.8%) received 2L and third-line tx, respectively. The most common 2L therapies were IO monotherapy (44.1%) and EV monotherapy (23.9%). After discontinuation of avelumab 1LM, 81 pts (43.5%) received 2L tx, 48 (59.3%) of those received EV; median OS from start of 2L EV was 12.7 months (7.2-16.5). Conclusions: These rw study findings demonstrate avelumab 1LM effectiveness for pts whose disease has not progressed on 1L PBC and provides evidence of the use of 2L EV after avelumab 1LM. There was an increased uptake of avelumab 1LM since its FDA approval. Survival outcomes are consistent with the JAVELIN Bladder 100 clinical trial and other rw studies that had shorter follow-up. We observed high IO monotherapy use despite the platinum-ineligible population typically making up 11% of pts with la/mUC. 1 Some of these pts treated with IO monotherapy may benefit from alternative 1L regimens. Future rw studies are needed to further characterize contemporary tx patterns, optimal tx sequencing, and survival in pts with la/mUC amidst the evolving tx landscape. 1 Gupta S, et al. JNCI 2024;116(4):547–554.