A quinolone derivative with potential antineoplastic activity. Semaxanib reversibly inhibits ATP binding to the tyrosine kinase domain of vascular endothelial growth factor receptor 2 (VEGFR2), which may inhibit VEGF-stimulated endothelial cell migration and proliferation and reduce the tumor microvasculature. This agent also inhibits the phosphorylation of the stem cell factor receptor tyrosine kinase c-kit, often expressed in acute myelogenous leukemia cells. or A substance that has been studied in the treatment of cancer. It belongs to the families of drugs called angiogenesis inhibitors and tyrosine kinase inhibitors. Also called SU5416.