Based on data generated by BiPar/Sanofi, it is concluded that iniparib does not possess characteristics typical of the PARP inhibitor class. The exact mechanism has not yet been fully elucidated, however based on experiments on tumor cells performed in the laboratory, iniparib is a novel investigational anti-cancer agent that induces gamma-H2AX (a marker of DNA damage) in tumor cell lines, induces cell cycle arrest in the G2/M phase in tumor cell lines, and potentiates the cell cycle effects of DNA damaging modalities in tumor cell lines. Investigations into potential targets of iniparib and its metabolites are ongoing.