Pyrosequencing assay for BRCA1methylation analysis: results from a cross-validation study

Epithelial Ovarian Cancers (EOCs) harboring germline or somatic pathogenic variants in BRCA1and BRCA2genes show sensitivity to poly(ADP-ribose) polymerase (PARP) inhibition. It has been suggested that BRCA1promoter methylation is perhaps a better determinant of therapy response, due to its intrinsic dynamic feature, with respect to genomic scars or gene mutation. Conflicting evidence was reported so far and the lack of a validated assay to measure promoter methylation was considered a main confounding factor in data interpretation. To contribute to the validation process of a pyrosequencing assay for BRCA1promoter methylation, 109 EOCs from two Italian centers were reciprocally blindly investigated. By comparing two different pyrosequencing assays, addressing a partially overlapping region of BRCA1promoter, an almost complete concordance of results was obtained. Moreover, the clinical relevance of this approach was also supported by the finding of BRCA1transcript downregulation in BRCA1methylated EOCs.