A poly(ADP-ribose) polymerase (PARP) -1 and -2 inhibitor with chemosensitizing and antitumor activities. With no antiproliferative effects as a single agent at therapeutic concentrations, ABT-888 inhibits PARPs, thereby inhibiting DNA repair and potentiating the cytotoxicity of DNA-damaging agents. PARP nuclear enzymes are activated by DNA single or double strand breaks, resulting in the poly(ADP-ribosyl)ation of other nuclear DNA binding proteins involved in DNA repair; poly(ADP-ribosyl)ation contributes to efficient DNA repair and to survival of proliferating cells exposed to mild genotoxic stresses as induced by as oxidants, alkylating agents or ionizing radiation.

A substance being studied in the treatment of breast cancers caused by mutations (changes) in the BRCA1 and BRCA2 genes. It is also being studied in the treatment of other types of cancer. It blocks an enzyme involved in many functions of the cell, including the repair of DNA damage. DNA damage may be caused by normal cell actions, UV light, some anticancer drugs, and radiation used to treat cancer. ABT-888 may cause cancer cells to die. It is a type of poly(ADP-ribose) polymerase inhibitor.