PARP1 and cancer: PARP inhibitors are selective for targeting tumors deficient in the HR DNA repair factor BRCA1 or BRCA2 (BRCA1/2)741 or compromised HR.733 Six PARP inhibitors are currently approved for the clinical treatment of cancer patients including the specific subgroups with BRCA1/2 mutation: olaparib, rucaparib, niraparib, talazoparib, fuzuloparib, and pamiparib733 (Table 9).