Mechanism of action

From the NCI Drug Dictionary: A synthetic, small molecule targeting the kinesin spindle protein (KSP) with potential antineoplastic activity. KSP inhibitor ARRY-520 specifically inhibits KSP (kinesin-5 or Eg5), resulting in activation of the spindle assembly checkpoint, induction of cell cycle arrest during the mitotic phase, and consequently cell death in tumor cells that are actively dividing.