FLT4 and neoplasm: To date two drugs, lenvatinib and sorafenib, have been approved by the US Food and Drug Administration for treatment of advanced DTC.35 Both drugs are thought to exert their actions by targeting tumor angiogenesis, acting as potent inhibitors of the vascular endothelial growth factor receptors, VEGFR-1, VEGFR-2, and VEGFR-3.