Breast cancer (BRCA) gene testing in ovarian cancer

The discovery of cancer-causing BRCA1/2 mutations and the emergence of genetic testing have brought precision in patient selection for poly-(ADP)-ribose polymerase inhibitor (PARPi) treatment. Interestingly, patients who are carriers of BRCA1/2 mutations have a higher risk for developing cancer, but respond better to DNA-damaging cytotoxic therapy, such as platinum-based chemotherapy. The distinctive biology of ovarian cancer involves high genomic instability consisting of gene amplification, gene deletion, oncogene hypomethylation, loss of heterozygosity, and tumor suppressor gene promoter hypermethylation in many of the DNA damage response (DDR) genes, including BRCA1/2. Several of these genetic abnormalities can impair high fidelity DNA damage repair increasing the therapeutic audience for PARPi's. This is especially important given the clinical development over the last decade of this group of agents and the dramatic increase in progression free survival among ovarian cancer patients who received PARPi, both in treatment or maintenance setting. In this review, we summarize our current understanding of the role of BRCA1/2 mutations in ovarian cancer and present relevant clinical trials in which BRCA1/2 was investigated as biomarker for therapy. We also outline the role of homologous recombination (HR) deficiency as biomarker by presenting the recent clinical development and recent approvals PARPi for firstline maintenance in ovarian cancer.