Olaparib, the first PARP inhibitor to gain regulatory approval, is now FDA-approved in advanced ovarian [20], breast [21], pancreatic [22] and prostate cancers [23], with the PARP inhibitors rucaparib [24], niraparib [25] and talazoparib [26] also FDA-approved in varying indications [17,27]. Here, PARP1 is linked to prostate cancer.