Targeting the DNA repair defect of BRCA tumours.

Carriers of heterozygous mutations in BRCA1 or BRCA2 are strongly predisposed to breast and ovarian cancers. Cancers arising in these individuals have consistently lost the wild-type allele during tumour progression, and are therefore deficient in BRCA1 or BRCA2 function. Both BRCA1 and BRCA2 proteins have been implicated in the repair of double-strand DNA breaks by homologous recombination. This functional role in DNA repair could be exploited in the treatment of BRCA-deficient cancers by targeting the tumours with drugs that create DNA damage highly reliant on BRCA1 or BRCA2 for repair.