RET and neoplasm: One of these is regorafenib, an oral multikinase inhibitor (MKI) that blocks the activity of multiple protein kinases involved in oncogenes (KIT, RET, RAF, and BEAF), tumor angiogenesis (VEGFR1, VEGFR2, VEGFR3, and TIE2), and the tumor microenvironment (PDGFR and FGFR).