Based on data generated by BiPar/Sanofi, it was concluded that iniparib does not possess characteristics typical of the poly (ADP-ribose) polymerase (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.