Long‐Term Response to Avelumab Maintenance Therapy and Durable Remission After Cessation in a Patient With Metastatic Urothelial Carcinoma of the Renal Pelvis: A Case Report

Introduction Metastatic urothelial carcinoma (UC) of the renal pelvis is an aggressive malignancy with a poor prognosis. Although avelumab maintenance therapy is a standard of care for advanced UC, long‐term durable remission after treatment cessation is rare. Case Presentation We report the case of a 71‐year‐old female with metastatic UC of the renal pelvis who achieved a partial response to gemcitabine and cisplatin chemotherapy. She subsequently underwent 40 courses of avelumab maintenance therapy, which she later chose to discontinue. The partial response initially achieved with gemcitabine and cisplatin chemotherapy has been maintained for over 2 years without further intervention following the cessation of avelumab maintenance therapy. Conclusion This case highlights avelumab's potential to induce a profound and durable antitumor immune response, suggesting the possibility of a “functional cure” in a subset of patients. This provides valuable data for guiding clinical decisions on the optimal duration of therapy.