JAVEMACS chart review study of avelumab maintenance in patients with advanced urothelial carcinoma (aUC) in Japan: Analyses of subgroups defined by second-line (2L) treatment.

e16550 Background: Avelumab maintenance is approved in Japan for patients with curatively unresectable UC not progressed after platinum-based chemotherapy (PBC). We report data from the JAVEMACS chart review study of avelumab maintenance in Japan in subgroups defined by 2L treatment. Methods: This multicenter, retrospective study collected data from medical charts of patients with aUC who started avelumab maintenance after first-line (1L) PBC between Feb 2021 and Dec 2023. Results: At data cutoff (Jun 2024) in the full analysis set (N = 350), 67 patients (19.1%) were still receiving avelumab; of 283 who discontinued, 200 (70.7%) received 2L treatment, which was enfortumab vedotin (EV) in 133 (66.5%), PBC in 41 (20.5%; gemcitabine + cisplatin [GC] in 25 [12.5%]; gemcitabine + carboplatin [GCarbo] in 15 [7.5%]; dose-dense methotrexate, vinblastine, doxorubicin, cisplatin in 1 [0.5%]), pembrolizumab (Pem) in 17 (8.5%), and others in 9 (4.5%). In the 2L EV, PBC, and Pem subgroups, respectively, median age at start of avelumab was 73/70/71 yr; primary tumor site was bladder in 44.4%/61.0%/64.7% and renal pelvis/ureter in 54.1%/39.0%/35.3%; 1L PBC was GC in 58.6%/63.4%/58.8% and GCarbo in 33.1%/31.7%/23.5%; and no. of 1L PBC cycles was 1-3 in 21.8%/19.5%/17.6%, 4 in 58.6%/53.7%/64.7%, 5-6 in 15.0%/26.8%/5.9%, and ≥7 in 4.5%/0%/11.8%. Median duration of avelumab was 15.3/10.1/15.1 wk, respectively. In the 2L EV, PBC, and Pem subgroups, respectively, objective response rate (ORR)/disease control rate (DCR) of best overall response with avelumab were 16.8%/49.6%, 13.9%/44.4%, and 25.0%/56.3%; ORR/DCR with 2L treatment were 45.8%/72.9% with 2L EV, 25.8%/61.3% with 2L PBC, and 8.3%/33.3% with 2L Pem. Third-line treatment was received by 36/133 patients after 2L EV (Pem, 61.1%; PBC, 25.0%), 34/41 after 2L PBC (EV, 50.0%; Pem, 38.2%; PBC, 2.9%), and 10/17 after 2L Pem (EV, 60.0%; PBC, 30.0%). Table shows outcomes in 2L subgroups. Conclusions: JAVEMACS provides insights about treatment patterns in patients receiving avelumab maintenance. EV was the most common 2L treatment. A treatment sequence of 1L PBC followed by avelumab maintenance and 2L EV was associated with improved outcomes vs sequences with 2L PBC or Pem. Median (95% CI), mo n OS from start of avelumab PFS2 from start of avelumab TNT-D2 from start of avelumab Full analysis set 350 31.8 (24.6-NE) 20.8 (15.5-30.6) 21.3 (16.1-26.3) 2L analysis set 200 24.3 (20.2-31.8) 12.9 (11.3-15.0) 14.0 (12.3-15.9) 2L EV 133 31.8 (20.6-NE) 13.3 (11.3-17.4) 15.1 (13.6-24.6) 2L PBC 41 23.5 (16.9-NE) 12.3 (6.9-15.9) 8.5 (6.6-14.0) 2L Pem 17 24.3 (15.3-NE) 12.3 (6.9-25.0) 11.8 (7.2-25.0) NE, not estimable; OS, overall survival; PFS2, progression-free survival 2 (time to progression with 2L treatment or death); TNT-D2, time to next treatment or death 2 (time to third-line treatment initiation or death).