A key example of this therapeutic approach is provided by ovarian cancer where patients in the ARIEL2 study with a BRCA mutation or with a “BRCA-like” LOH-based signature but no BRCA mutation had better responses and longer progression-free survival to the PARP inhibitor rucaparib than BRCA wild-type patients lacking this signature [12]. Here, PARP1 is linked to ovarian carcinoma.