title: Phenotypic and metabolic investigation of a CSF-1R kinase receptor inhibitor (BLZ945) and its pharmacologically active metabolite.
abstract: 1. 4-[2((1R,2R)-2-Hydroxycyclohexylamino)-benzothiazol-6-yloxyl]-pyridine-2-carboxylic acid methylamide (BLZ945) is a small molecule inhibitor of CSF-1R kinase activity within osteoclasts designed to prevent skeletal related events in metastatic disease. Key metabolites were enzymatically and structurally characterized to understand the metabolic fate of BLZ945 and pharmacological implications. The relative intrinsic clearances for metabolites were derived from in vitro studies using human hepatocytes, microsomes and phenotyped with recombinant P450 enzymes. 2. Formation of a pharmacologically active metabolite (M9) was observed in human hepatocytes. The M9 metabolite is a structural isomer (diastereomer) of BLZ945 and is about 4-fold less potent. This isomer was enzymatically formed via P450 oxidation of the BLZ945 hydroxyl group, followed by aldo-keto reduction to the alcohol (M9). 3. Two reaction phenotyping approaches based on fractional clearances were applied to BLZ945 using hepatocytes and liver microsomes. The fraction metabolized (fm) or contribution ratio was determined for each metabolic reaction type (oxidation, glucuronidation or isomerization) as well as for each metabolite. The results quantitatively illustrate contribution ratios of the involved enzymes and pathways, e.g. the isomerization to metabolite M9 accounted for 24% intrinsic clearance in human hepatocytes. In summary, contribution ratios for the Phase I and Phase II pathways can be determined in hepatocytes.
authors.affiliation: Department of Drug Metabolism and Pharmacokinetics, Novartis Institutes for BioMedical Research , Basel , Switzerland .
authors.forename: Joel A
authors.initials: JA
authors.lastname: Krauser
authors.forename: Yi
authors.initials: Y
authors.lastname: Jin
authors.forename: Markus
authors.initials: M
authors.lastname: Walles
authors.forename: Ulrike
authors.initials: U
authors.lastname: Pfaar
authors.forename: James
authors.initials: J
authors.lastname: Sutton
authors.forename: Marion
authors.initials: M
authors.lastname: Wiesmann
authors.forename: Daniel
authors.initials: D
authors.lastname: Graf
authors.forename: Veronique
authors.initials: V
authors.lastname: Pflimlin-Fritschy
authors.forename: Thierry
authors.initials: T
authors.lastname: Wolf
authors.forename: Gian
authors.initials: G
authors.lastname: Camenisch
authors.forename: Piet
authors.initials: P
authors.lastname: Swart
mesh_terms: D052160:Benzothiazoles / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D022781:Hepatocytes / Q000201:enzymology*; D006801:Humans; D053858:Metabolic Networks and Pathways; D008862:Microsomes, Liver / Q000201:enzymology*; D010848:Picolinic Acids / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: C568289:4-(2-(2-hydroxycyclohexylamino)benzothiazol-6-yloxy)pyridine-2-carboxylic acid methylamide; D052160:Benzothiazoles; D010848:Picolinic Acids; D047428:Protein Kinase Inhibitors; D003577:Cytochrome P-450 Enzyme System; D016186:Receptor, Macrophage Colony-Stimulating Factor
keywords: Contribution ratio; enzyme phenotyping; in vitro clearance; in vitro metabolism; metabolic isomerization