Evaluation of avelumab first-line (1L) maintenance therapy and subsequent treatment (tx) in patients (pts) with locally advanced or metastatic urothelial carcinoma (la/mUC) using a large claims database in Japan: JAVEMACS-D.

700 Background: In Japan, avelumab was approved in Feb 2021 as maintenance therapy for pts with curatively unresectable UC that had not progressed after platinum-based chemotherapy (PBC) based on phase 3 data from JAVELIN Bladder 100 showing prolonged overall survival. We report initial data from JAVEMACS-D, a real-world study of pts who received avelumab 1L maintenance therapy using a large claims database in Japan (Medical Data Vision). Methods: JAVEMACS-D is a longitudinal, observational, retrospective study of adults with la/mUC who had received PBC and had a first dose of avelumab maintenance therapy between Feb 2021 and Apr 2023. Pt characteristics and tx patterns were analyzed using descriptive statistics. Results: 773 pts were included. Median observation period was 14.0 mo from start of avelumab and 20.2 mo from start of 1L PBC. Median age was 74 y (interquartile range [IQR], 69.0-79.0), and 189 pts (24.5%) were aged ≥80 y. Primary tumor location was bladder in 463 (59.9%) and renal pelvis/ureter in 330 (42.7%). Prior 1L PBC tx was gemcitabine (gem) + cisplatin (cis) in 474 (61.3%), gem + carboplatin (carbo) in 281 (36.4%), dose-dense MVAC in 8 (1.0%), and others in 10 (1.3%). Use of 1L gem + carbo was more common in pts aged ≥80 y (101/189 [53.4%]) or pts with a primary tumor in the renal pelvis/ureter (142/330 [43.0%]) vs the overall cohort. Number of PBC cycles was ≤3 in 139 (18.0%), 4 in 260 (33.6%), 5-6 in 224 (29.0%), and ≥7 in 150 (19.4%). Avelumab therapy was started in 2021 in 289 (37.4%) and in 2022 or later in 484 (62.6%). Receipt of ≥7 cycles of 1L PBC was less common in pts who started avelumab in 2022 or later vs 2021 (80 [16.5%] vs 70 [24.2%]). Median interval between PBC and avelumab was 5.0 wk (IQR, 3.6-6.9); the interval was <4 wk in 239 (30.9%), 4-10 wk in 474 (61.3%), and >10 wk in 60 (7.8%). At data cutoff (Oct 2023), 170 (22.0%) were still receiving avelumab, 394 (51.0%) had received second-line (2L) tx, and 209 (27.0%) discontinued avelumab without 2L tx. The most common 2L tx was enfortumab vedotin (EV) in 185 of 394 pts (47.0%), gem + cis/carbo in 122 (31.0%), and pembrolizumab in 65 (16.5%); 2L EV was more common in pts who started avelumab in 2022 or later vs 2021 (123/221 [55.7%] vs 62/173 [35.8%]). The most common third-line tx after 2L EV (n=40) was pembrolizumab in 19 (47.5%) and gem + cis/carbo in 18 (45.0%). Conclusions: JAVEMACS-D provides the largest real-world dataset of pts in Japan with la/mUC treated with avelumab maintenance therapy to date. The number of prior PBC cycles was generally 6 or lower in pts who started avelumab in 2022 or later. Although pts treated with avelumab were not resistant to PBC, EV was more common than PBC as 2L tx after avelumab, particularly in pts treated more recently, highlighting the evolving tx landscape.