Identification of a Fumarate-Hydratase Deficient-like RCC Subtype with Convergent Pathway Alterations

The development of molecularly targeted therapies builds upon the identification of tumor clades with shared molecular abnormalities. Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is a familial syndrome resulting from germline mutation of the two-hit tumor suppressor gene, Fumarate Hydratase (FH). HLRCC renal tumors present often in young adults, exhibit unique histological features and are particularly aggressive. HLRCC is uncommon and poorly understood, and whether there are sporadic renal tumors with similar characteristics, is unclear. Notably, FH can also be inactivated somatically in RCC, and should be included among FH-deficient (FHD) kidney tumors. We identified a tumor clade without FH mutations but with similar morphological and molecular characteristics as well as aggressive clinical behavior, which we name FHDL (FHD-like). We show that FHD/FHDL tumors represent a unique subtype of CIMP (CpG Island Methylator Phenotype) with the highest levels of overall genome methylation and CDKN2A silencing. FHD/FHDL tumors are characterized by convergent activation of the Hippo pathway as determined by frequent and mutually exclusive mutations in NF2 and PTPN14. AKR1B10, an NRF2 target, was upregulated in FHD/FHDL tumors as well as GATA3, which suggests a shared origin in the renal medulla and is consistent with topological studies. There is loss of 5-hydroxymethylcytosine in both FHD and FHDL tumors. These data define a group of particularly aggressive renal cancers with shared molecular features and potential targets for therapeutic intervention.EGA study EGAS00001002646