Multiple Bone Metastases From Non-Muscle Invasive Bladder Cancer Responding to Combination Therapy With Enfortumab Vedotin and Pembrolizumab: A Case Report.

Introduction: We report a case in which combination therapy with enfortumab vedotin (EV) and pembrolizumab proved effective in treating non-muscle-invasive bladder cancer (NMIBC) accompanied by multiple bone metastases. Case Presentation: A 61-year-old man with NMIBC underwent eight transurethral resections of bladder tumor (TURBTs) at another hospital over 4 years. During the eighth TURBT, carcinoma in situ was detected, and the patient was treated with intravesical Bacillus Calmette-Guérin (BCG) therapy. A computed tomography scan performed at our hospital 1.5 years after BCG therapy revealed multiple osteosclerotic lesions. Cystoscopy and bladder magnetic resonance imaging revealed no obvious tumorous lesions. An incisional biopsy of the sternum confirmed the diagnosis of multiple bone metastases originating from NMIBC. The patient was started on combination therapy with EV and pembrolizumab. After 5 months, bone scintigraphy revealed decreased accumulation. Conclusion: Combination therapy with EV and pembrolizumab was also effective in treating NMIBC with multiple bone metastases.