The tert-butylamine salt form of LY3295668, an orally bioavailable inhibitor of the serine/threonine protein kinase aurora A, with potential antimitotic and antineoplastic activities. Upon administration, aurora A kinase inhibitor LY3295668 targets, binds to and inhibits the activity of aurora A kinase. This 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, overexpressed in a wide variety of cancers, plays an essential role in the regulation of spindle assembly and mitosis.