Outcomes of advanced urothelial carcinoma following discontinuation of programmed death (PD)-1 or PD-ligand (L)-1 inhibitors.

385 Background: The outcomes and therapy of advanced urothelial carcinoma (UC) patients (pts) following discontinuation of PD-1/PD-L1 inhibitors are unclear. We performed a retrospective analysis to examine the frequency of systemic therapy administered following PD-1/PD-L-1 inhibitors and outcomes in these pts. Methods: Data were collected from institutions for pts with advanced UC following prior PD-1/PD-L1 inhibitors as salvage therapy. Baseline demographics and therapy administered following prior check-point inhibitors was captured. Univariable Cox regression analyses examined clinical factors potentially associated with overall survival (OS) following check-point inhibitors. Results: Data from 62 pts were available from 4 institutions with capture of therapy and outcomes following checkpoint inhibitor immunotherapy. The median age was 65.5 years and 51 (82.3%) were male. The median duration of PD-1/PD-L1 inhibitors available from 55 pts was 64 days (range 7-669). Of these pts, 22 (35.5%) received post-PD1/PD-L1 pathway inhibitor therapy with a variety of chemotherapy (n = 16), chemobiologic combination (n = 1), biologic agents (n = 4) and immunotherapy (n = 1). The median time from last PD1/PD-L1 pathway inhibitor therapy to subsequent therapy was 58 days (range 14-242). The median OS of all pts following completion of PD-1/PD-L1 inhibitors was 149 days (95% CI: 75-359). Among pts who received some post-PD1/PD-L1 pathway inhibitor therapy, median OS was 182 days (95% CI: 121-372), and the median time to progression was 124 days (95% CI: 61-273) when examining from start of post-PD1/PD-L1 therapy. Among these 22 pts, the only significant baseline prognostic factor associated with OS was performance status. Conclusions: In this dataset, 35.5% of pts with advanced UC received subsequent systemic therapy following salvage therapy with PD1/PD-L1 inhibitors. Outcomes with subsequent therapy appear similar to historically observed outcomes in pts who had not received prior PD1/PD-L1 inhibitors. Further study of pts post-PD1/PD-L1 inhibitor therapy is warranted to identify factors associated with outcomes and potentially synergistic sequences.