An orally bioavailable, small-molecule receptor tyrosine kinase (RTK) inhibitor with potential antineoplastic activity. Linifanib inhibits members of the vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) receptor families; it exhibits much less activity against unrelated RTKs, soluble tyrosine kinases, or serine/threonine kinases. This agent does not have a general antiproliferative effect due to its high dose requirement. However, linifanib may exhibit potent antiproliferative and apoptotic effects on tumor cells whose proliferation is dependent on mutant kinases, such as fms-related tyrosine kinase receptor-3 (FLT3).