All these mechanisms lead to the development of synthetic lethality in BRCA1/2 deficient cancers following PARP inhibitor treatment, and several PARP inhibitors including olaparib (LynparzaTM), niraparib (ZejulaTM) and rucaparib (RubracaTM) have now been approved by the FDA and/or the European Medicines Agency for the maintenance treatment of platinum-sensitive, recurrent HGSOC with or without BRCA1/2 mutations [14, 20–24]. Here, BRCA1 is linked to cancer.