title: Identification of Three Novel Ring Expansion Metabolites of KAE609, a New Spiroindolone Agent for the Treatment of Malaria, in Rats, Dogs, and Humans.
abstract: KAE609 [(1'R,3'S)-5,7'-dichloro-6'-fluoro-3'-methyl-2',3',4',9'-tetrahydrospiro[indoline-3,1'-pyridol[3,4-b]indol]-2-one] is a potent, fast-acting, schizonticidal agent being developed for the treatment of malaria. After oral dosing of KAE609 to rats and dogs, the major radioactive component in plasma was KAE609. An oxidative metabolite, M18, was the prominent metabolite in rat and dog plasma. KAE609 was well absorbed and extensively metabolized such that low levels of parent compound (≤11% of the dose) were detected in feces. The elimination of KAE609 and metabolites was primarily mediated via biliary pathways (≥93% of the dose) in the feces of rats and dogs. M37 and M23 were the major metabolites in rat and dog feces, respectively. Among the prominent metabolites of KAE609, the isobaric chemical species, M37, was observed, suggesting the involvement of an isomerization or rearrangement during biotransformation. Subsequent structural elucidation of M37 revealed that KAE609, a spiroindolone, undergoes an unusual C-C bond cleavage, followed by a 1,2-acyl shift to form a ring expansion metabolite M37. The in vitro metabolism of KAE609 in hepatocytes was investigated to understand this novel biotransformation. The metabolism of KAE609 was qualitatively similar across the species studied; thus, further investigation was conducted using human recombinant cytochrome P450 enzymes. The ring expansion reaction was found to be primarily catalyzed by cytochrome P450 (CYP) 3A4 yielding M37. M37 was subsequently oxidized to M18 by CYP3A4 and hydroxylated to M23 primarily by CYP1A2. Interestingly, M37 was colorless, whereas M18 and M23 showed orange yellow color. The source of the color of M18 and M23 was attributed to their extended conjugated system of double bonds in the structures.
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.) Su.huskey@novartis.com.
authors.forename: Su-Er W
authors.initials: SE
authors.lastname: Huskey
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Chun-qi
authors.initials: CQ
authors.lastname: Zhu
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Lin
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Ry R
authors.initials: RR
authors.lastname: Forseth
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Helen
authors.initials: H
authors.lastname: Gu
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Oliver
authors.initials: O
authors.lastname: Simon
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Fabian K
authors.initials: FK
authors.lastname: Eggimann
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Matthias
authors.initials: M
authors.lastname: Kittelmann
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Alexandre
authors.initials: A
authors.lastname: Luneau
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Alexandra
authors.initials: A
authors.lastname: Vargas
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Hongmei
authors.initials: H
authors.lastname: Li
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Lai
authors.initials: L
authors.lastname: Wang
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Heidi J
authors.initials: HJ
authors.lastname: Einolf
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Sarah
authors.initials: S
authors.lastname: Favara
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: Handan
authors.initials: H
authors.lastname: He
authors.affiliation: Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research, East Hanover, New Jersey (S.-E.W.H., C.Z., R.R.F., H.G., H.L., L.W., H.J.E., J.Z., S.F., H.H., J.B.M.); Technical Research and Development, Novartis Pharma, East Hanover, NJ (M.M.L.); Novartis Institute for Tropical Diseases, Singapore (O.S.); and Global Discovery Chemistry, Bioreactions Group, Novartis Institutes for BioMedical Research, Basel, Switzerland (F.K.E., M.K., A.L., A.V.).
authors.forename: James B
authors.initials: JB
authors.lastname: Mangold
mesh_terms: D000818:Animals; D001646:Bile / Q000378:metabolism; D001711:Biotransformation / Q000187:drug effects; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004285:Dogs; D005243:Feces / Q000737:chemistry; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D006900:Hydroxylation; D007211:Indoles / Q000378:metabolism* / Q000494:pharmacology*; D008288:Malaria / Q000188:drug therapy*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013141:Spiro Compounds / Q000378:metabolism* / Q000494:pharmacology*
chemical_list: D007211:Indoles; C552304:NITD 609; D013141:Spiro Compounds; C057812:indoline; D003577:Cytochrome P-450 Enzyme System