PF-03814735 is a novel, potent, orally bioavailable, reversible small-molecule Aurora kinase inhibitor with IC50 of 0.8, 5, 10 and 22 nM for Aurora 1, Aurora 2, Flt 1 and FAk, respectively. Aurora kinases are serine- threonine kinases that play essential roles in mitotic checkpoint control during mitosis. PF-03814735 possesses potential antineoplastic activity. Aurora kinase inhibitor PF-03814735 binds to and blocks Aurora kinases A and B, which may result in the prevention of cellular division and proliferation in tumor cells that overexpress these kinases. In intact cells, the preventive activity of PF-03814735 on the Aurora1 and Aurora2 kinases attenuates levels of phospho-Aurora1, phosphohistone H3, and phospho-Aurora2. PF-03814735 generates a block in cytokinesis, leading to prevention of cell proliferation and the formation of polyploid multinucleated cells. Although PF-03814735 generates significant prevention of several other protein kinases, the predominant biochemical effects in cellular assays are consistent with inhibition of Aurora kinases. Once-daily oral injection of PF-03814735 to mice bearing human xenograft tumors generates an attenuation in phosphohistone H3 in tumors at doses that are tolerable and that result in significant inhibition of tumor growth. The combination of PF-03814735 and docetaxel in xenograft mouse tumor models shows additive tumor growth inhibition. PF-03814735 is originally developed by Pfizer. The phase I clinical trials for the treatment of solid tumors has been completed.