Clinical Feasibility of Platinum-Based Chemotherapy Followed by Avelumab Maintenance after Enfortumab Vedotin plus Pembrolizumab in Metastatic Urothelial Carcinoma: A Case Series.

<p>Introduction: The introduction of enfortumab vedotin plus pembrolizumab (EVP) has caused a paradigm shift in the first-line treatment strategies for metastatic urothelial carcinoma (mUC). However, no standard subsequent therapy has been established after EVP therapy, and the role of platinum-based chemotherapy (PBC) followed by avelumab maintenance therapy remains unclear. Case Presentation: We report three cases of mUC treated with EVP followed by PBC and subsequent avelumab maintenance therapy. As the first-line treatment, EVP achieved disease control in all cases; however, disease progression or treatment discontinuation occurred. Subsequent PBC resulted in stable disease or partial response. Afterward, patients were transitioned to avelumab maintenance therapy, which resulted in further tumor regression or sustained disease control, even in patients with prior pembrolizumab exposure and those who discontinued EVP therapy due to adverse events. Conclusion: PBC is often considered as a subsequent treatment after EVP therapy, except in patients with FGFR gene alterations. PBC followed by avelumab maintenance therapy may represent a feasible subsequent treatment option for selected patients with mUC who achieve disease control after EVP therapy.