Olaparib is a selective and potent inhibitor of poly (ADP-ribose) polymerase (PARP) enzymes, PARP1 and PARP2. PARP inhibitors represent a novel class of anti-cancer therapy and they work by taking advantage of a defect in DNA repair in cancer cells with BRCA mutations and inducing cell death. Olaparib is used to treat a number of BRCA-associated tumours, including ovarian cancer, breast cancer, pancreatic cancer, and prostate cancer.