PARP1 and cancer: Since these early clinical trials, the efficacy of PARP inhibitors has been even further explored in other cancers, most notably BRCA1/2-deficient cancers due to the increased sensitivity to PARP inhibition that these mutations confer (16, 17) Presently, four PARP inhibitors have been approved by the Food and Drug Administration (FDA) for cancer treatment, specifically ovarian, breast, pancreatic, and prostate cancer: olaparib, niraparib, rucaparib, and talazoparib (Table 1) (18, 19).