ARRY 520 hydrochloride is a kinesin spindle protein (KSP) inhibitor.ARRY 520 hydrochloride induces cell death by apoptosis and has potent anti-proliferative activity.

ARRY 520 causes accumulation of cells in the G2/M phase of the cell cycle in a dose-dependent manner in HeLa cells[1]. ARRY 520 induces mitotic arrest in multiple cell lines and exhibits anti-proliferative against a broad range of human and rodent tumor cell lines, including a variety of leukemias and solid tumors[1].ARRY 520 induces apoptosis in a dose-dependent manner in HeLa cells[1]. ARRY 520 potently induces cell cycle block and subsequent death in leukemic cells via the mitochondrial pathway and has potential to eradicate AML progenitor cells[2]. ARRY 520 is able to induce caspase-2 activation[3]. ARRY 520 is cytotoxic in Type II EOC cells[3].

ARRY 520 has anti-tumor activitiy in vivo. ARRY 520 induced a decrease in tumor kinetics in a dose-dependent manner in female nude mice, EOC mice xenograft model[3].