Identification of novel fumarate hydratase gene alterations in prostate cancer.

11585 Background: Fumarate hydratase (FH), an enzyme involved in the Krebs cycle, plays a crucial role in the generation of energy and oxygenation of cells. Genomic alterations (GAs) of FH, a tumor suppressor gene, have been shown to cause chronic hypoxia that encourages tumor formation and have been linked to hereditary leiomyomatosis and renal cell cancer. Only few reports have associated FH mutations with other cancers, and none in prostate cancer. Methods: Identification of an FH V435M pathogenic alteration, which likely changes fumarate binding kinetics, in a prostate cancer patient, with negative family history for renal cancer and cutaneous leiomyomatosis, led to review of a database of 1781 prostate cancer patients, whose tissue was assayed by hybrid-capture based comprehensive genomic profiling (CGP) in the course of clinical care to evaluate genomic alterations (GA: base substitutions, indels, amplifications, copy number alterations, fusions/rearrangements) and targeted therapy opportunities. Tumor mutational burden (TMB) was calculated from a minimum of 1.11 Mb sequenced DNA and reported as mutations/Mb. Results: Profiling identified 49 prostate adenocarcinoma patients (3%) with FH gene alterations, 2 of which harbored the V435M GA identified in the original prostate patient. Ten of 40 alterations were H476_k477 insertions, in the C terminus domain, and 14 were amplifications. The rest were variants of unknown significance (VUS). Conclusions: A FH GA, known to impact other cancers, found in a prostate cancer, led to the discovery of a frequency that suggests deregulation of metabolic pathway activation may contribute to prostate cancer pathogenesis for a subset of patients. The somatic FH GA’s are likely to be substantially more common than germline mutations, and identifying metabolic-enzyme mutations that are pathogenic in prostate cancer could lead to pharmacologic manipulations that are more effective and less toxic than existing therapies. No FDA approved therapies currently exist for this patient’s tumor type nor of any other tumor type with FH GA’s. In our case, alterations in the C-terminal binding domain of FH might inform drug development.