Advanced fumarate hydratase-deficient renal cell carcinoma responding to combination immune checkpoint inhibitors.

Fumarate hydratase deficient (FHdef) renal cell carcinoma (RCC) is rare, highly aggressive and is believed to arise mostly in the setting of hereditary leiomyomatosis RCC (HLRCC) syndrome with a germline mutation of fumarate hydratase (FH) gene. There is currently little evidence regarding the most effective systemic treatment for advanced FHdef RCC. We present three cases of metastatic FHdef RCC, all achieving tumor response with combination immunotherapy ipilimumab and nivolumab (Ipi/Nivo). A 50-year-old male, a 27-year-old male and a 48-year-old female. The clinical features, diagnosis and medical imaging are reviewed.