Sequential therapy for hereditary leiomyomatosis and renal cell cancer-associated renal cell carcinoma: a case report and report of a new family pedigree.

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a rare autosomal-dominant disorder caused by a heterozygous germline mutation in the fumarate hydratase (FH) gene. HLRCC is clinically characterized by the development of three tumors: uterine leiomyomata, cutaneous leiomyomata, and renal cell carcinoma (RCC). HLRCC-associated RCC is aggressive and diagnosed at a much earlier age than sporadic RCC. It is essential for carriers of HLRCC to undergo annual renal screening by magnetic resonance imaging to detect early stage RCCs. Metastatic HLRCC-associated RCC must be treated by systemic therapy; however, it is unclear which medicines are most effective in treating this cancer owing to its low incidence rate. Immune checkpoint inhibitor (ICI) combinations or ICIs plus tyrosine kinase inhibitors are administered as systemic therapy for clear cell RCC. Here, we report a patient with HLRCC-associated RCC treated with sequential therapy, including ipilimumab plus nivolumab combination and cabozantinib, after diagnosis of HLRCC-associated RCC using FoundationOne Liquid CDx and single-site analysis. We also investigated familial FH mutations and describe a new family pedigree for HLRCC.