Inhibits endogenous poly-ADP-ribosyltransferases often present in membrane preparations with minimal effect of bacterial toxin mediated ADP-ribosylation. Inhibits nitric oxide-induced apoptosis but not/ differentiation in HL-60 cells. Protects cells from oxygen radical and nitric oxide toxicity. Inhibits stressinduced apoptosis

ABT-888 is a potent, orally bioavailable inhibitor of PARP-1 and PARP-2 (potency ≤5nM in vitro). ABT-888 does not inhibit other NAD-binding enzymes and has minimal CYP450 inhibition and induction. ABT-888 increases tumor growth delay resulting from radiation and DNA-damaging agents. It shows broad spectrum of chemoand radiopotentiation. The ability to potentiate temozolomide (TMZ) and develop a biological marker for PARP inhibition was evaluated in vivo. ABT-888 does not show inherent cytotoxicity and shows no single agent activity in tumor models. It has excellent bioavailability and good blood-brain permeation.