AVENANCE real-world study of avelumab first-line (1L) maintenance treatment for advanced urothelial carcinoma (UC): Analyses in low tumor burden subgroups.

718 Background: The effectiveness and safety of avelumab 1L maintenance was confirmed in the large real-world AVENANCE study in France. In patients with advanced UC, low tumor burden is associated with a better prognosis, which may inform treatment decisions. Here, we report post hoc analyses from AVENANCE in subgroups with disease characteristics associated with low tumor burden. Methods: AVENANCE (NCT04822350) is a noninterventional ambispective study that enrolled patients with locally advanced or metastatic UC who were progression free after 1L platinum-based chemotherapy (PBC) and who had previous, ongoing, or planned avelumab 1L maintenance treatment. The primary endpoint is overall survival (OS) from the start of avelumab treatment. In post hoc analyses, OS and progression-free survival (PFS) were analyzed in subgroups who had locally advanced disease, nonvisceral metastases (excluding bone), or lymph node (LN)–only disease at the start of PBC. Results: Of patients with available data in the overall effectiveness population (N=595), 49 (8.3%) had locally advanced disease, 80 (14.7%) had nonvisceral metastases, and 61 (10.3%) had LN-only disease. At data cutoff (July 15, 2024) in the overall effectiveness population, median follow-up from start of avelumab was 33.2 months (95% CI, 31.7-34.2), median OS was 21.2 months (95% CI, 17.3-23.3), and median PFS was 5.7 months (95% CI, 5.2-6.6). In subgroups with locally advanced disease, nonvisceral metastases, or LN-only disease, median OS (95% CI) was not reached (17.4 months-not estimable [NE]), 27.2 months (16.8-NE), and not reached (19.9 months-NE), and median PFS (95% CI) was 19.8 months (9.6-NE), 9.0 months (5.8-16.1), and 13.4 months (6.9-26.5), respectively. Subsequent treatment was received by 17 patients (34.7%) with locally advanced disease (enfortumab vedotin [EV] in 3 [6.1%]), 45 patients (56.3%) with nonvisceral metastases (EV in 12 [15.0%]), and 33 patients (54.1%) with LN-only disease (EV in 8 [13.1%]). Conclusions: Subgroup analyses from AVENANCE show pronounced clinical benefits with avelumab 1L maintenance in subgroups with low tumor burden characteristics. Results are consistent with previous analyses from JAVELIN Bladder 100 and other real-world studies (eg, READY, an Italian compassionate use program) and further support the use of avelumab 1L maintenance as a standard of care in patients with advanced UC without progression after 1L PBC, including those with low tumor burden. Clinical trial information: NCT04822350 .