Avelumab first-line (1L) maintenance for advanced urothelial carcinoma (UC): Long-term follow-up from the JAVELIN Bladder 100 trial in subgroups defined by 1L chemotherapy regimen and analysis of overall survival (OS) from start of 1L chemotherapy.

Abstract

508 Background: For platinum-eligible patients (pts) with advanced UC, 1L cisplatin- or carboplatin-based chemotherapy regimens followed by avelumab maintenance in pts without progression has become the standard of care. This is based on the results of the phase 3 JAVELIN Bladder 100 trial (NCT02603432), which showed significantly longer OS and progression-free survival (PFS) from start of maintenance (randomization) with avelumab maintenance + best supportive care (BSC) vs BSC alone (median OS, 23.8 vs 15.0 months; HR, 0.76 [95% CI, 0.63-0.91]; p=0.0036). We report post hoc analyses of long-term outcomes by 1L chemotherapy regimen and OS from start of 1L chemotherapy. Methods: Pts with unresectable locally advanced or metastatic UC that did not progress with 4-6 cycles of 1L cisplatin + gemcitabine or carboplatin + gemcitabine were randomized 1:1 to receive avelumab + BSC (n=350) or BSC alone (n=350). The primary endpoint was OS measured from randomization. Secondary endpoints included PFS and safety. Results: At data cutoff (June 4, 2021), median follow-up from randomization was ≥38 months in both arms. In subgroups treated with 1L cisplatin + gemcitabine or carboplatin + gemcitabine, OS and PFS (measured from start of maintenance [randomization]) were longer in the avelumab + BSC arm than in the BSC alone arm (Table). Safety findings were similar in both subgroups. In the overall population, median OS measured from the start of 1L chemotherapy was 29.7 months (95% CI, 25.2-34.0) in the avelumab + BSC arm and 20.5 months (95% CI, 19.0-23.5) in the BSC alone arm (HR, 0.77 [95% CI, 0.635-0.921]). Conclusions: Long-term follow-up from the JAVELIN Bladder 100 trial confirms that avelumab 1L maintenance provides similar OS and PFS benefits in pts with advanced UC who are progression free following standard-of-care 1L cisplatin- or carboplatin-based chemotherapy, with an acceptable safety profile. The median OS measured from start of chemotherapy further supports the use of avelumab 1L maintenance as standard of care in this setting and provides a benchmark for future clinical trials. Clinical trial information: NCT02603432 . [Table: see text]