N-desmethyl Regorafenib N-oxide is an active metabolite of the multi-kinase inhibitor regorafenib .1 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.2
1.Li, Y.-H., Lin, Q.-M., Pang, N.-H., et al.Functional characterization of 27 CYP3A4 protein variants to metabolize regorafenib in vitroBasic Clin. Pharmacol. Toxicol.125(4)337-344(2019) 2.Zopf, D., Heinig, R., Thierauch, K.-H., et al.Abstract 1666: Regorafenib (BAY 73-4506): Preclinical pharmacology and clinical identification and quantification of its major metabolitesCancer. Res.70(8 Suppl.)(2010)