N-Desmethyl Regorafenib N-oxide, an active metabolite of the multi-kinase inhibitor regorafenib, originates through the action of the cytochrome P450 (CYP) isoform CYP3A4. This compound demonstrates efficacy in vitro by inhibiting key enzymes such as VEGFR2, Tie2, c-Kit, and B-RAF, and it exhibits tumor growth inhibition in HT-29 and MDA-MB-231 mouse xenograft models at a dosage of 1 mg/kg.