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

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. 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. 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