A multikinase inhibitor with potential antineoplastic activity. Multikinase inhibitor 4SC-203 selectively inhibits FMS-related tyrosine kinase 3 (FLT3/STK1), FLT3 mutated forms, and vascular endothelial growth factor receptors (VEGFRs). This may result in the inhibition of angiogenesis and cell proliferation in tumor cells in which these kinases are upregulated. FLT3 (FLK2), a class III tyrosine kinase receptor, is overexpressed or mutated in most B lineage and acute myeloid leukemias (AML). VEGFRs, tyrosine kinase receptors, are overexpressed in a variety of tumor cell types and play key roles in angiogenesis.