Preclinical characterization of PF-00868554, a potent nonnucleoside inhibitor of the hepatitis C virus RNA-dependent RNA polymerase.
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.
Shi
Stephanie T
ST
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
Herlihy
Koleen J
KJ
Graham
Joanne P
JP
Nonomiya
Jim
J
Rahavendran
Sadayappan V
SV
Skor
Heather
H
Irvine
Rebecca
R
Binford
Susan
S
Tatlock
John
J
Li
Hui
H
Gonzalez
Javier
J
Linton
Angelica
A
Patick
Amy K
AK
Lewis
Cristina
C
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
D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D012324:RNA-Dependent RNA Polymerase