Introduction: Poly(ADP-ribose) polymerase (PARP) inhibitors, including rucaparib, are the only targeted class of therapeutics approved for recurrent epithelial ovarian carcinoma with a predictive biomarker. Currently, three different PARP inhibitors are approved for either the treatment of ovarian cancer or maintenance of remission following chemotherapy. The Foundation Focus CDxBRCA is an FDA-cleared next-generation sequencing tumor tissue assay that detects somatic and sometimes germline mutations in BRCA1 and BRCA2 genes.Areas covered: The authors discuss the evolution of the ovarian cancer genomic testing landscape relative to PARP inhibition, with a focus on Foundation Focus CDxBRCA and CDxBRCA Loss of Heterozygosity (LOH), the complementary diagnostics (CDx) to rucaparib.Expert opinion: Relatively early in PARP inhibitor development, women with somatic and/or germline mutations in the BRCA1 and BRCA2 genes were found to have higher response rates to PARP inhibitors with longer durability than women who were BRCA wildtype. Other measures of homologous recombination deficiency including LOH have proven to be predictive biomarkers also. Because PARP biomarkers are genomic and complex, co-development of high-performance companion diagnostics was a high priority. The Foundation Focus test began as a next-generation sequencing assay capable of detecting germline (gBRCA) and somatic (sBRCA) mutations that predict response to rucaparib treatment. The addition of LOH to the assay was validated by a clinical trial supporting expansion of the Rucaparib FDA label to include maintenance of chemotherapy response.
Keywords: PARP inhibitor; Rucaparib; companion diagnostic; foundation focus; homologous recombination deficiency; loss of heterozygosity (LOH); next-generation sequencing; ovarian cancer; predictive biomarker.