Paclitaxel is necessary for improved survival in epithelial ovarian cancers with homologous recombination gene mutations

PURPOSE: To investigate the impact of somatic mutations in homologous recombination (HR) genes on the chemotherapeutic response and survival of patients with epithelial ovarian cancer (EOC). EXPERIMENTAL DESIGN: We performed targeted massively parallel sequencing of tumor DNA from 158 patients with EOC. We associated adjuvant chemotherapy and clinical outcome with mutations in selected genes, focusing on those encoding HR proteins. RESULTS: HR mutations were found in 47 (30%) tumors. We did not detect an overall survival (OS) difference in advanced stage patients whose tumors had HR mutations compared to those without (median OS of 49.6 months (95% CI 29.9-57.7) vs. 43.3 months (95% CI 31.9-75.47), p = 0.87). However, when stratified by chemotherapy regimen, patients whose tumors had TP53 and HR mutations demonstrated a marked survival advantage when treated with platinum and paclitaxel vs. platinum +/− cyclophosphamide (median OS of 90 months (95% CI 50-NA) vs. 29.5 months (95% CI 17.7-50.5), p = 0.0005). CONCLUSIONS: Previous studies demonstrating a survival advantage for EOC patients with somatic HR mutations have been conducted with almost universal use of both platinum and paclitaxel. Our study is the first to our knowledge to compare cohorts with somatic HR gene mutations treated with and without paclitaxel containing platinum regimens. The survival benefit attributed to the platinum sensitivity of HR deficient ovarian cancers may depend upon the combined use of paclitaxel.