A phase II clinical trial to analyze olaparib response in patients with BRCA1 and/or BRCA2 promoter methylation with advanced breast cancer (GEICAM/2015-06 COMETA-Breast study).

TPS1114Background: Identification of targeted therapies for advanced triple negative breast cancer(TNBC) remains as an important clinical challenge. TNBC frequently shows BRCA dysfunction and 80% of germlineBRCA1 mutation (gBRCAm) carriers with BC diagnosis are TNBC patients (pts). In addition to germline mutations, epigenetic silencing by aberrant methylation of BRCA1/2 promoters can be responsible for a dysfunctional BRCA protein. Methylationof BRCA1 promoter occurs in 15-57% of TNBCs. Interestingly, BRCA1-methylated sporadic breast tumors display pathologic features and gene expression profiles similar to those of gBRCAm carriers, a phenotype called “BRCAness”. Olaparib(O) is an oral poly( ADP-ribose) polymerase( PARP) inhibitorapproved by the FDA for treatment of gBRCA-mutated HER2-negativemetastatic BC. Tuttet al. have shown antitumor activity in gBRCA-mutated advanced TNBC (54% Objective Response Rate [ORR]). We report an ongoing phase II clinical trial to analyze the O efficacy in advanced T...