Avelumab first-line (1L) maintenance therapy in advanced urothelial carcinoma: Final analysis from a real-world study in the UK.

723 Background: In the JAVELIN Bladder 100 phase 3 trial, avelumab 1L maintenance therapy plus best supportive care (BSC) significantly improved overall survival (OS) and progression-free survival (PFS) vs BSC alone in patients with locally advanced or metastatic urothelial carcinoma (la/mUC) that had not progressed with 1L platinum-based chemotherapy (PBC). In the UK, initial access to avelumab was provided via the Early Access to Medicines Scheme (EAMS) from September 2020. This study reports 24-month real-world outcomes in patients treated with avelumab 1L maintenance via the EAMS in the UK. Methods: Patients aged ≥18 years who had been diagnosed with la/mUC, demonstrated at least stable disease following 1L PBC, and initiated avelumab since October 2020 were recruited consecutively from 10 UK hospitals. Primary outcomes included real-world OS, real-world PFS, and treatment patterns by 24 months. Recruitment was completed in June 2022, and all patients had completed 24 months of follow-up from avelumab initiation by June 2024. Results: Of 106 patients recruited, 78 (73.6%) were male. Median age at diagnosis of la/mUC was 72 years. Primary tumor site was bladder in 40 (78%), and the most common metastatic sites were lymph node in 64 (60.4%), lung in 31 (33%), and bone in 20 (21.3%). ECOG performance status was 0 in 35 (33.0%),1 in 36 (34%), 2-4 in 5 (4.7%), and not recorded in 30 (28.3%). 1L PBC was carboplatin/gemcitabine in 55 (51.9%) and cisplatin/gemcitabine in 49 (46.2%). Response to 1L PBC was partial or complete response in 63 (60.0%). From avelumab initiation, median OS was 16.8 months (95% CI, 11.6-23.4) and median PFS was 8.7 months (95% CI, 7.1-14.2). Median OS from the start of 1L PBC in this population without disease progression after 1L PBC was 21.8 months (95% CI, 17.0-28.9). In subgroup analyses of patients who had received 1L carboplatin/gemcitabine or cisplatin/gemcitabine, median OS from avelumab initiation was 14.4 months (95% CI, 10.1-not estimable [NE]) and 21.4 months (95% CI, 15.4-NE), and median OS from start of 1L PBC was 19.5 months (95% CI, 14.8-NE) and 26.7 months (95% CI, 20.5-NE), respectively. Conclusions: These results provide evidence of the clinical effectiveness of avelumab 1L maintenance therapy in patients who were progression free following 1L PBC in a UK real-world setting. Median OS was shorter than previously observed in the JAVELIN Bladder 100 trial, which may be due to the worse ECOG performance status and higher proportion of patients who had received 1L carboplatin-based chemotherapy in this real-world population.