title: Development of a Fluorescence-based Trypanosoma cruzi CYP51 Inhibition Assay for Effective Compound Triaging in Drug Discovery Programmes for Chagas Disease.
abstract: Chagas disease, caused by the protozoan parasite Trypanosoma cruzi (T. cruzi), is a life threatening global health problem with only two drugs available for treatment (benznidazole and nifurtimox), both having variable efficacy in the chronic stage of the disease and high rates of adverse drug reactions. Inhibitors of sterol 14α-demethylase (CYP51) have proven effective against T. cruzi in vitro and in vivo in animal models of Chagas disease. Consequently two azole inhibitors of CYP51 (posaconazole and ravuconazole) have recently entered clinical development by the Drugs for Neglected Diseases initiative. Further new drug treatments for this disease are however still urgently required, particularly having a different mode of action to CYP51 in order to balance the overall risk in the drug discovery portfolio. This need has now been further strengthened by the very recent reports of treatment failure in the clinic for both posaconazole and ravuconazole. To this end and to prevent enrichment of drug candidates against a single target, there is a clear need for a robust high throughput assay for CYP51 inhibition in order to evaluate compounds active against T. cruzi arising from phenotypic screens. A high throughput fluorescence based functional assay using recombinantly expressed T. cruzi CYP51 (Tulahuen strain) is presented here that meets this requirement. This assay has proved valuable in prioritising medicinal chemistry resource on only those T. cruzi active series arising from a phenotypic screening campaign where it is clear that the predominant mode of action is likely not via inhibition of CYP51.
authors.affiliation: Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee, United Kingdom.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Riley
authors.affiliation: Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee, United Kingdom.
authors.forename: Stephen
authors.initials: S
authors.lastname: Brand
authors.affiliation: CYPEX, Dundee, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Voice
authors.affiliation: Molecular Discovery Research-Tres Cantos, GlaxoSmithKline, Centro de Investigación Básica, Tres Cantos, Spain.
authors.forename: Ivan
authors.initials: I
authors.lastname: Caballero
authors.affiliation: Molecular Discovery Research-Tres Cantos, GlaxoSmithKline, Centro de Investigación Básica, Tres Cantos, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Calvo
authors.affiliation: Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee, United Kingdom.
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Read
mesh_terms: D058888:14-alpha Demethylase Inhibitors / Q000302:isolation & purification* / Q000494:pharmacology; D000818:Animals; D000981:Antiprotozoal Agents / Q000302:isolation & purification* / Q000494:pharmacology; D014355:Chagas Disease / Q000188:drug therapy / Q000469:parasitology; D055808:Drug Discovery / Q000379:methods; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D005453:Fluorescence; D005470:Fluorometry / Q000379:methods*; D057166:High-Throughput Screening Assays / Q000379:methods; D006801:Humans; D058886:Sterol 14-Demethylase / Q000378:metabolism*; D014349:Trypanosoma cruzi / Q000187:drug effects* / Q000201:enzymology
chemical_list: D058888:14-alpha Demethylase Inhibitors; D000981:Antiprotozoal Agents; D058886:Sterol 14-Demethylase