PDGFRB and neoplasm: Regorafenib is a sorafenib-derived multi-kinase inhibitor that targets tumor cells and their microenvironment due to inhibition of angiogenic (VEGFR1-2 and TIE-2), stromal (PDGFRβ and FGFR1), oncogenic (RET and c-KIT), and intracellular (BRAF, c-RAF/Raf-1) kinases.