Difference of oncological efficacy between two immune checkpoint inhibitors following first-line platinum-based chemotherapy in patients with unresectable, metastatic, advanced urothelial carcinoma: a multicenter real-world Japanese cohort.

Background: Maintenance avelumab is currently recommended for patients with unresectable and/or metastatic (mUC) achieving at least stable disease (SD) on first-line platinum-based chemotherapy (1L-CT). Pembrolizumab is an alternative therapeutic avenue for this patient cohort in clinical practice. We investigated real-world data, focusing on the correlation between response to 1L-CT and oncological efficacy of subsequent immune checkpoint inhibitor (ICI) therapy with avelumab or pembrolizumab. Methods: A multicenter database registered 626 patients with mUC diagnosed from 2008–2023; among these, 175 receiving 2–6 cycles of 1L-CT followed by ICI therapy. Patients were categorized based on response to 1L-CT using the Response Evaluation Criteria in Solid Tumors (v1.1). Objective response rate on ICI, progression to ICI-free survival (ICI-PFS), and overall survival from start of 1L-CT were compared between avelumab-treated and pembrolizumab-treated patients in each response subgroup. Results: ICI-PFS was significantly longer in patients achieving partial response on 1L-CT and subsequently receiving pembrolizumab compared to those receiving avelumab. Notably, patients achieving SD on 1L-CT and subsequently receiving pembrolizumab manifested significantly higher objective response rate (14% and 41%, respectively) and prolonged ICI-PFS relative to those receiving avelumab. In contrast, overall survival did not delineate difference between patients treated with avelumab versus pembrolizumab. Similar findings were discerned in the subanalysis of patients having favorable SD (tumor shrinkage, from − 29 to 0%) and unfavorable SD (tumor enlargement, from + 1 to + 19%) on 1L-CT. Conclusions: Our study provides real-world evidence regarding difference of oncological efficacy between maintenance avelumab and subsequent pembrolizumab in patients with mUC who achieved partial response or SD on 1L-CT. [ABSTRACT FROM AUTHOR]