Real-world effectiveness and treatment (tx) patterns in patients (pts) with locally advanced/metastatic urothelial carcinoma (la/mUC) receiving avelumab first-line maintenance (1LM) in Japan: Results from the JAVEMACS chart review study.

701 Background: Avelumab 1LM was approved in Feb 2021 in Japan based on results of the JAVELIN Bladder 100 phase 3 trial, which showed prolonged overall survival (OS) in pts with la/mUC that had not progressed with platinum-based chemotherapy (PBC). We report the primary analysis from a chart review study of pts with la/mUC receiving avelumab 1LM in Japan. Methods: This multicenter retrospective study reviewed medical charts of pts with la/mUC who received 1L PBC and started avelumab 1LM between Feb 2021 and Dec 2023. Pt characteristics, effectiveness, and tx patterns were analyzed. Results: The study included 354 pts. At data cutoff (Jun 2024), median observation period was 14.6 mo from start of avelumab and 19.8 mo from start of 1L PBC. At the start of avelumab, median age was 73 y (range, 43-93), 261 pts (73.7%) were male, and ECOG PS was 0 in 287 (81.1%), 1 in 57 (16.1%), and ≥2 in 6 (1.7%). Primary tumor location was bladder in 179 (50.6%) and renal pelvis/ureter in 170 (48.0%). 1L PBC was gemcitabine (gem) + cisplatin (cis) in 198 (55.9%) and gem + carboplatin (carbo) in 117 (33.1%); 101 pts (28.5%) were cis eligible, and 187 (52.8%) were cis ineligible/platinum eligible. Number of PBC cycles was 1-3 in 71 (20.1%), 4 in 206 (58.2%), 5-6 in 61 (17.2%), and ≥7 in 16 (4.5%). Median time from start of PBC to start of avelumab was 19.1 wk (IQR, 15.4-24.1). At last follow-up, 68 (19.2%) were still receiving avelumab, 202 (57.1%) had received second-line (2L) tx, and 84 (23.7%) had received third-line (3L) tx. The most common 2L and 3L tx were enfortumab vedotin (EV) in 134 (66.3%) and 25 (29.8%), cis/carbo + gem in 41 (20.3%) and 13 (15.5%), and pembrolizumab in 17 (8.4%) and 37 (44.0%), respectively. OS analyses are shown in the Table. Conclusions: Avelumab 1LM seems to provide long-term OS benefits in this population of pts with la/mUC that had not progressed with 1L PBC in clinical practice in Japan. Adequate 1L PBC selection may result in long-term OS regardless of cis eligibility. Although pts were not resistant to PBC, 2L EV was more common than 2L PBC after avelumab 1LM, highlighting the evolving tx landscape. OS, median (95% CI), mo OS from start of avelumab 1LM OS from start of 1L PBC* OS from start of 2L Overall (N=354) 31.8 (24.6-NE) 38.9 (35.6-NE) - 1L PBC Gem + cis (n=198) NE (31.2-NE) 40.8 (37.6-NE) - Gem + carbo (n=117) 24.3 (19.5-30.6) 28.9 (23.9-NE) - Platinum eligibility Cis eligible (n=101) 31.2 (20.0-NE) 38.9 (26.9-NE) - Cis ineligible/platinum eligible (n=187) 31.8 (22.6-NE) 38.7 (26.3-NE) - 2L analysis set (n=202) 24.3 (20.2-31.2) 31.3 (26.3-38.7) 15.1 (13.2-20.1) EV (n=134) 31.8 (20.6-NE) 37.2 (26.6-60.6) 17.8 (11.9-NE) PBC (n=42) 23.5 (16.9-NE) 26.9 (22.2-NE) 15.1 (11.6-NE) NE, not estimable. *Population included only pts without disease progression after 1L PBC and survived to receive avelumab 1LM.