title: Preclinical characterization of PF-00868554, a potent nonnucleoside inhibitor of the hepatitis C virus RNA-dependent RNA polymerase.
abstract: PF-00868554 is a nonnucleoside inhibitor of the hepatitis C virus (HCV) RNA polymerase, which exerts its inhibitory effect by binding to the thumb base domain of the protein. It is a potent and selective inhibitor, with a mean 50% inhibitory concentration of 0.019 microM against genotype 1 polymerases and a mean 50% effective concentration (EC(50)) of 0.075 microM against the genotype 1b-Con1 replicon. To determine the in vitro antiviral activity of PF-00868554 against various HCV strains, a panel of chimeric replicons was generated, in which polymerase sequences derived from genotype 1a and 1b clinical isolates were cloned into the 1b-Con1 subgenomic reporter replicon. Our results indicate that PF-00868554 has potent in vitro antiviral activity against a majority (95.8%) of genotype 1a and 1b replicons, with an overall mean EC(50) of 0.059 microM. PF-00868554 showed no cytotoxic effect in several human cell lines, up to the highest concentration evaluated (320 microM). Furthermore, the antiviral activity of PF-00868554 was retained in the presence of human serum proteins. An in vitro resistance study of PF-00868554 identified M423T as the predominant resistance mutation, resulting in a 761-fold reduction in susceptibility to PF-00868554 but no change in susceptibility to alpha interferon and a polymerase inhibitor that binds to a different region. PF-00868554 also showed good pharmacokinetic properties in preclinical animal species. Our results demonstrate that PF-00868554 has potent and broad-spectrum antiviral activity against genotype 1 HCV strains, supporting its use as an oral antiviral agent in HCV-infected patients.
authors.affiliation: Department of Cancer Biology, Pfizer Global Research and Development, La Jolla Laboratories, 10724 Science Center Drive, San Diego, CA 92121, USA. stephanie.shi@pfizer.com
authors.forename: Stephanie T
authors.initials: ST
authors.lastname: Shi
authors.forename: Koleen J
authors.initials: KJ
authors.lastname: Herlihy
authors.forename: Joanne P
authors.initials: JP
authors.lastname: Graham
authors.forename: Jim
authors.initials: J
authors.lastname: Nonomiya
authors.forename: Sadayappan V
authors.initials: SV
authors.lastname: Rahavendran
authors.forename: Heather
authors.initials: H
authors.lastname: Skor
authors.forename: Rebecca
authors.initials: R
authors.lastname: Irvine
authors.forename: Susan
authors.initials: S
authors.lastname: Binford
authors.forename: John
authors.initials: J
authors.lastname: Tatlock
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Javier
authors.initials: J
authors.lastname: Gonzalez
authors.forename: Angelica
authors.initials: A
authors.lastname: Linton
authors.forename: Amy K
authors.initials: AK
authors.lastname: Patick
authors.forename: Cristina
authors.initials: C
authors.lastname: Lewis
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D002460:Cell Line; D004285:Dogs; D024882:Drug Resistance, Viral; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005838:Genotype; D016174:Hepacivirus / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D008252:Macaca fascicularis; D008297:Male; D010641:Phenotype; D011485:Protein Binding; D012324:RNA-Dependent RNA Polymerase / Q000037:antagonists & inhibitors*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012093:Replicon / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D012324:RNA-Dependent RNA Polymerase