Durable Complete Metabolic Response to Enfortumab Vedotin plus Pembrolizumab in Metastatic Upper Tract Urothelial Carcinoma: A Case Report

Background: Upper tract urothelial carcinoma (UTUC) accounts for approximately 5–10% of urothelial malignancies and is frequently associated with advanced stage and aggressive clinical behavior. In metastatic disease, platinum-based chemotherapy has historically represented standard first-line therapy; however, long-term outcomes remain limited. The combination of enfortumab vedotin and pembrolizumab has recently demonstrated superior survival outcomes compared with platinum-based chemotherapy in advanced urothelial carcinoma. Nevertheless, the depth and durability of response following early discontinuation of antibody–drug conjugate therapy remain incompletely characterized. Case Presentation: A 38-year-old woman with metastatic UTUC involving liver, lymph nodes, peritoneum, ovary, and bone experienced disease progression after platinum-based chemotherapy. She received three cycles of enfortumab vedotin plus pembrolizumab. Cross-sectional imaging demonstrated near-complete radiologic response with resolution of hepatic metastases and marked regression of thoracic and abdominal lymphadenopathy. Enfortumab vedotin was discontinued due to treatment-related adverse effects, and pembrolizumab monotherapy was continued. At the sixth cycle of pembrolizumab, FDG PET/CT revealed complete metabolic resolution of all previously hypermetabolic lesions. The patient remains progression-free for more than eight months after documentation of complete metabolic response. Conclusion: This case illustrates sustained complete metabolic remission following short-course enfortumab vedotin combined with pembrolizumab in metastatic UTUC and supports the therapeutic potential of antibody–drug conjugate and immune checkpoint inhibitor combinations in advanced disease.