Clinical studies have confirmed the validity of the synthetic lethality approach and four different PARP inhibitors (PARPi; olaparib, rucaparib, niraparib and talazoparib) have been approved as monotherapies for BRCA-mutated or platinum-sensitive recurrent ovarian cancer and/or for BRCA-mutated HER2-negative metastatic breast cancer. Here, ERBB2 is linked to ovarian cancer.