FLT1 and neoplasm: Regorafenib is an oral tyrosine kinase inhibitor that blocks multiple protein kinase activities, including proteins involved in the regulation of oncogenesis (KIT, RET, RAF-1 and BRAF), tumour microenvironment (PDGFR and FGFR) and tumour angiogenesis (VEGFR1, 2 and 3 and TIE-2) [15,16].