Regorafenib (BAY 73-4506) mesylate is an orally active and potent multi-targeted receptor tyrosine kinase inhibitor, with IC 50 values of 13/4.2/46, 22, 7, 1.5 and 2.5 nM for VEGFR1/2/3 , PDGFRβ , Kit , RET and Raf-1 , respectively. Regorafenib mesylate shows very robust antitumor and antiangiogenic activity.