title: Nitroreductase gene-directed enzyme prodrug therapy: insights and advances toward clinical utility.
abstract: This review examines the vast catalytic and therapeutic potential offered by type I (i.e. oxygen-insensitive) nitroreductase enzymes in partnership with nitroaromatic prodrugs, with particular focus on gene-directed enzyme prodrug therapy (GDEPT; a form of cancer gene therapy). Important first indications of this potential were demonstrated over 20 years ago, for the enzyme-prodrug pairing of Escherichia coli NfsB and CB1954 [5-(aziridin-1-yl)-2,4-dinitrobenzamide]. However, it has become apparent that both the enzyme and the prodrug in this prototypical pairing have limitations that have impeded their clinical progression. Recently, substantial advances have been made in the biodiscovery and engineering of superior nitroreductase variants, in particular development of elegant high-throughput screening capabilities to enable optimization of desirable activities via directed evolution. These advances in enzymology have been paralleled by advances in medicinal chemistry, leading to the development of second- and third-generation nitroaromatic prodrugs that offer substantial advantages over CB1954 for nitroreductase GDEPT, including greater dose-potency and enhanced ability of the activated metabolite(s) to exhibit a local bystander effect. In addition to forging substantial progress towards future clinical trials, this research is supporting other fields, most notably the development and improvement of targeted cellular ablation capabilities in small animal models, such as zebrafish, to enable cell-specific physiology or regeneration studies.
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand.
authors.forename: Elsie M
authors.initials: EM
authors.lastname: Williams
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand.
authors.forename: Rory F
authors.initials: RF
authors.lastname: Little
authors.affiliation: Auckland Cancer Society Research Centre, University of Auckland, Auckland 1023, New Zealand.
authors.forename: Alexandra M
authors.initials: AM
authors.lastname: Mowday
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand.
authors.forename: Michelle H
authors.initials: MH
authors.lastname: Rich
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand.
authors.forename: Jasmine V E
authors.initials: JV
authors.lastname: Chan-Hyams
authors.affiliation: Michael Smith Laboratories, University of British Columbia, Vancouver V6T 1Z4, BC, Canada.
authors.forename: Janine N
authors.initials: JN
authors.lastname: Copp
authors.affiliation: Auckland Cancer Society Research Centre, University of Auckland, Auckland 1023, New Zealand Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, Auckland 1023, New Zealand.
authors.forename: Jeff B
authors.initials: JB
authors.lastname: Smaill
authors.affiliation: Auckland Cancer Society Research Centre, University of Auckland, Auckland 1023, New Zealand Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, Auckland 1023, New Zealand.
authors.forename: Adam V
authors.initials: AV
authors.lastname: Patterson
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand Maurice Wilkins Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, Auckland 1023, New Zealand david.ackerley@vuw.ac.nz.
authors.forename: David F
authors.initials: DF
authors.lastname: Ackerley
mesh_terms: D000818:Animals; D001388:Aziridines / Q000627:therapeutic use*; D019020:Directed Molecular Evolution; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics / Q000627:therapeutic use; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D009374:Neoplasms, Experimental / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D009601:Nitroreductases / Q000096:biosynthesis / Q000235:genetics / Q000627:therapeutic use; D011355:Prodrugs / Q000627:therapeutic use*
chemical_list: D001388:Aziridines; D029968:Escherichia coli Proteins; D011355:Prodrugs; C100099:tretazicar; C116054:NfsB protein, E coli; D009601:Nitroreductases
keywords: cancer gene therapy; directed evolution; nitro-heterocycle; nitroaromatic; nitroreductase (NTR); oxidoreductase; prodrug