A Case of Metastatic Fumarate Hydratase-Deficient–like Renal Cell Carcinoma Successfully Managed by Ipilimumab plus Nivolumab

We report a 62-year-old male with metastatic fumarate hydratase-deficient renal cell carcinoma (FH-deficient RCC) without fumarate hydratase (FH) mutation (FH-deficient–like RCC). The International Metastatic RCC Database Consortium risk score was intermediate, and immunotherapy with nivolumab and ipilimumab (Ipi/Nivo) was initiated. Four cycles of Ipi/Nivo and 5 cycles of nivolumab resulted in a complete response of the metastases. Hypophysitis occurred as an immune-related adverse event after four cycles of Ipi/Nivo. The prognosis of patients with FH-deficient RCC is generally poor. Few reports of FH-deficient RCC successfully treated with Ipi/Nivo have been published. Ipi/Nivo can be effective for treating FH-deficient RCC.