Potent inhibitor of PARP-1 and PARP-2 (potency ≤5nM in vitro). Does not inhibit other NAD-binding enzymes. Has minimal CYP450 inhibition and induction. Shows broad spectrum of chemo- and radiopotentiation. Enantiomeric purity ≥97% suitable for in vivo studies. Does not show inherent cytotoxicity and shows no single agent activity in tumor models. Has excellent bioavailability and good blood-brain permeation. Increases tumor growth delay resulting from radiation and DNA-damaging agents.