An orally bioavailable inhibitor of the serine/threonine protein kinase aurora A, with potential antimitotic and antineoplastic activities. Upon intravenous administration, aurora A kinase inhibitor TAS-119 binds to and inhibits aurora A kinase, which may result in disruption of the assembly of the mitotic spindle apparatus, disruption of chromosome segregation, inhibition of cell division and the induction of apoptosis in cells overexpressing aurora A kinase. Aurora A kinase localizes to the spindle poles and to spindle microtubules during mitosis; it plays an essential role in the regulation of spindle assembly. Aurora kinase A is overexpressed in a wide variety of cancers.