title: A UGT2B10 splicing polymorphism common in african populations may greatly increase drug exposure.
abstract: RO5263397 [(S)-4-(3-fluoro-2-methyl-phenyl)-4,5-dihydro-oxazol-2-ylamine], a new compound that showed promising results in animal models of schizophrenia, is mainly metabolized in humans by N-glucuronidation. Enzyme studies, using the (then) available commercial uridine 5'-diphosphate-glucuronosyltransferases (UGTs), suggested that UGT1A4 is responsible for its conjugation. In the first clinical trial, in which RO5263397 was administered orally to healthy human volunteers, a 136-fold above-average systemic exposure to the parent compound was found in one of the participants. Further administration in this trial identified two more such poor metabolizers, all three of African origin. Additional in vitro studies with recombinant UGTs showed that the contribution of UGT2B10 to RO5263397 glucuronidation is much higher than UGT1A4 at clinically relevant concentrations. DNA sequencing in all of these poor metabolizers identified a previously uncharacterized splice site mutation that prevents assembly of full-length UGT2B10 mRNA and thus functional UGT2B10 protein expression. Further DNA database analyses revealed the UGT2B10 splice site mutation to be highly frequent in individuals of African origin (45%), moderately frequent in Asians (8%) and almost unrepresented in Caucasians (<1%). A prospective study using hepatocytes from 20 individual African donors demonstrated a >100-fold lower intrinsic clearance of RO5263397 in cells homozygous for the splice site variant allele. Our results highlight the need to include UGT2B10 when screening the human UGTs for the enzymes involved in the glucuronidation of a new compound, particularly when there is a possibility of N-glucuronidation. Moreover, this study demonstrates the importance of considering different ethnicities during drug development.
authors.affiliation: Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland (S.F., H.K., P.S., D.T., R.D.N., M.C.H., O.S., V.A.I.); and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland (M.F., N.M.).
authors.forename: Stephen
authors.initials: S
authors.lastname: Fowler
authors.affiliation: Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland (S.F., H.K., P.S., D.T., R.D.N., M.C.H., O.S., V.A.I.); and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland (M.F., N.M.).
authors.forename: Heidemarie
authors.initials: H
authors.lastname: Kletzl
authors.affiliation: Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland (S.F., H.K., P.S., D.T., R.D.N., M.C.H., O.S., V.A.I.); and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland (M.F., N.M.).
authors.forename: Moshe
authors.initials: M
authors.lastname: Finel
authors.affiliation: Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland (S.F., H.K., P.S., D.T., R.D.N., M.C.H., O.S., V.A.I.); and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland (M.F., N.M.).
authors.forename: Nenad
authors.initials: N
authors.lastname: Manevski
authors.affiliation: Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland (S.F., H.K., P.S., D.T., R.D.N., M.C.H., O.S., V.A.I.); and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland (M.F., N.M.).
authors.forename: Paul
authors.initials: P
authors.lastname: Schmid
authors.affiliation: Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland (S.F., H.K., P.S., D.T., R.D.N., M.C.H., O.S., V.A.I.); and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland (M.F., N.M.).
authors.forename: Dietrich
authors.initials: D
authors.lastname: Tuerck
authors.affiliation: Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland (S.F., H.K., P.S., D.T., R.D.N., M.C.H., O.S., V.A.I.); and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland (M.F., N.M.).
authors.forename: Roger D
authors.initials: RD
authors.lastname: Norcross
authors.affiliation: Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland (S.F., H.K., P.S., D.T., R.D.N., M.C.H., O.S., V.A.I.); and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland (M.F., N.M.).
authors.forename: Marius C
authors.initials: MC
authors.lastname: Hoener
authors.affiliation: Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland (S.F., H.K., P.S., D.T., R.D.N., M.C.H., O.S., V.A.I.); and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland (M.F., N.M.).
authors.forename: Olivia
authors.initials: O
authors.lastname: Spleiss
authors.affiliation: Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland (S.F., H.K., P.S., D.T., R.D.N., M.C.H., O.S., V.A.I.); and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland (M.F., N.M.) victor_alejandro.iglesias@roche.com.
authors.forename: Victor A
authors.initials: VA
authors.lastname: Iglesias
mesh_terms: D044383:Black People / Q000235:genetics*; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D030561:Databases, Nucleic Acid; D020868:Gene Silencing; D020719:Glucuronides / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000235:genetics*; D006801:Humans; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D010080:Oxazoles / Q000008:administration & dosage / Q000493:pharmacokinetics*; D020641:Polymorphism, Single Nucleotide; D013379:Substrate Specificity; D053719:Tandem Mass Spectrometry
chemical_list: C000596180:4-(3-fluoro-2-methylphenyl)-4,5-dihydrooxazol-2-ylamine; D020719:Glucuronides; D010080:Oxazoles; C552162:UGT2B10 protein, human; D014453:Glucuronosyltransferase