Resumption of Enfortumab Vedotin Supported by Diagnosis of a Late- Onset Immune-Related Adverse Event in Metastatic Urothelial Carcinoma : A Case Report.

A 71-year-old man presented with exertional dyspnea. Chest radiography revealed multiple pulmonary nodules, and contrast-enhanced computed tomography showed findings suspicious of right renal pelvic cancer. Percutaneous lung tumor biopsy revealed a histological diagnosis of urothelial carcinoma, and right renal pelvic cancer cT3N2M1 was diagnosed. Favorable response was shown during primary chemotherapy with gemcitabine and cisplatin but resulted in tumor progression after four cycles. The patient was switched to a second-line treatment, pembrolizumab, which resulted in rapid tumor growth. Hyper-progression was suspected, and the patient was promptly switched to a third-line treatment, enfortumab vedotin. The tumor shrank significantly. After three treatment cycles, an adverse event of enteritis was observed. A biopsy of the intestinal mucosa led to a histopathologic diagnosis of late-onset immune-related adverse event; therefore, enfortumab vedotin could be continued.