LAUSR

BACKGROUND Genomic alterations that activate the MAPK signaling pathway frequently occur in Type I Epithelial Ovarian Cancers (EOCs). We evaluated therapeutic response outcomes in patients with type I EOC treated with genotype-matched therapy on clinical trials enrolled in a prospective molecular profiling program. MATERIAL AND METHODS Formalin fixed paraffin embedded tumor tissues were prospectively screened for genomic alterations using MALDI-ToF mass-spectrometry platform or targeted sequencing using the Illumina MiSeq TruSeq Amplicon Cancer Panel. Treatment outcomes on genotype-matched trials were retrospectively reviewed using RECIST version 1.1 and Gynecological Cancer Intergroup CA125 related-response criteria RESULTS: 55 patients with type I EOC underwent molecular profiling, 41 (75%) low grade serous (LGS), 9 (16%) clear cell (CC), and 5 (9%) mucinous (MC) histologies. Thirty-five patients (64%) were found to have ≥1 somatic mutations: 23 KRAS, 6 NRAS, 5 PIK3CA, 2 PTEN, 1 BRAF, 1 AKT, 1 TP53, and 1 CTNNB1. Fifteen patients were subsequently enrolled in genotype-matched phase I or II trials, including 14 patients with KRAS/NRAS mutations treated with MEK inhibitor targeted combinations. Among 14 RECIST evaluable patients, there were 7 partial responses (PR), 7 stable disease (SD) and 1 disease progression (PD). CA125 responses were observed in 10/10 evaluable KRAS/NRAS mutant patients treated with MEK inhibitor combinations CONCLUSIONS: Genotyping and targeted sequencing of Type I EOCs frequently identifies actionable mutations. Matched treatment with MEK-based combination therapy in KRAS and/or NRAS mutant type I EOC patients is an active therapeutic strategy.