N-desmethyl Regorafenib N-oxide is an active metabolite of the multi-kinase inhibitor regorafenib . It is formed from regorafenib by the cytochrome P450 (CYP) isoform CYP3A4. N-desmethyl Regorafenib N-oxide inhibits VEGFR2, Tie2, c-Kit, and B-RAF in vitro, as well as inhibits tumor growth in HT-29 and MDA-MB-231 mouse xenograft models when administered at a dose of 1 mg/kg.