Centromere-associated protein E (CENP-E) is a protein that is required for correct chromosomal alignment in mitosis. Loss of CENP-E activity, due to microinjection of antibodies, ablation of gene expression with siRNA or antisense oligonucleotides, or inhibition of enzymatic activity by small molecule inhibitors, causes aberrant cell cycle arrest in mitosis, characterized by a bipolar mitotic spindle with misaligned chromosomes. Studies with small molecule inhibitors have demonstrated that this aberrant cell cycle arrest can result in apoptosis and cell death. CENP-E has been shown to be abundantly expressed in a variety of human tumors. GSK923295 is a potent and selective CENP-E inhibitor which has demonstrated potent and broad spectrum antitumor activity against solid and hematologic malignancies in vitro. GSK923295 is intended for use either as a monotherapy or in combination with existing anti-cancer therapies.