Poly ADP-ribose polymerases (PARPs) are a family of enzymes related to DNA damage repair process. Inhibition of PARP1/2 accelerates the damage of injured DNA, which is synthetically lethal to DNA-repairing-deficient cancer cells, such as BRCA1/2-deficient cells. PARP1/2 inhibitors could be a promising candidate for the treatment of cancer. The PARP1 and PARP2 inhibition assays were performed by Medicilon.