Regorafenib is a multikinase inhibitor of tyrosine kinases involved in tumor angiogenesis mechanisms (e.g., PDGFR, FGFRs 1–2, VEGFRs 1–3, TIE2), tumor proliferation (e.g., RET, RAF, KIT), tumor microenvironment, and metastasis processes (VEGFR2–3, PDGFR), approved by the FDA and EMA for the treatment of refractory mCRC. The gene discussed is RET; the disease is neoplasm.