FLT1 and neoplasm: Regorafenib is an oral multi-targeted TKI, whose targets are involved in the regulation of tumor angiogenesis (VEGFR1–3 and TEK), oncogenesis (KIT, RET, RAF1, BRAF, and and BRAFV600E), and maintenance of the tumor microenvironment (PDGFRA, PDGFRB and FGFR) (7).