Avelumab was approved for the treatment of urothelial carcinoma in Japan in 2021, and its use as maintenance therapy for metastatic urothelial carcinoma is expanding.

We conducted a retrospective study of 19 patients who received avelumab as maintenance therapy from January 2022 to September 2024 at our hospital.

The median age at the start of treatment was 73 years (60-88 years). Radical surgery was performed before chemotherapy in 11 patients, and postoperative adjuvant therapy was performed in 4 of them. The histological types were all urothelial carcinomas, with no cases of variants. Primary treatment consisted of GCis therapy in 10 cases and GCb therapy in 9 cases. The median follow-up period after induction of chemotherapy was 18.5 months (7-38 months). The dose was 10 mg/kg every 2 weeks in all patients. The performance status at induction was 1 or less in all patients. The median number of avelumab administrations was 9 (1-48). The maximum efficacy was complete response in 2 cases, partial response in 3 cases, stable disease in 10 cases, and progression disease in 4 cases, and disease control rate was 78.9%. The median duration of efficacy was 3.5 months (0-32 months); only 6 patients had had grade 3 or higher adverse events: interstitial pneumonia in 2 cases and polymyalgia rheumatica in 1 case, and treatment was discontinued due to adverse events in 3 cases.

The therapeutic efficacy and safety of avelumab as maintenance therapy for metastatic urothelial carcinoma cancer were reconfirmed.