Filibuvir. RNA-directed RNA polymerase (NS5B) inhibitor, Treatment of hepatitis C virus infection

Filibuvir is a non-nucleoside inhibitor (NNI) of the hepatitis C virus (HCV) RNA-directed RNA polymerase (NS5B). Specifically, filibuvir works by noncovalently binding to the "thumb 2" pocket of NS5B. Phase I monotheropy studies demonstrated that filibuvir is safe, well tolerated and resulted in a rapid reduction in HCV RNA. Results from a 4-week phase Ila study of three doses of filibuvir given in combination with pegylated interferon (peg-IFN) and ribavirin, followed by 44 weeks of peg-IFN and ribavirin, showed an increased rapid virological response rate (RVR; undetectable HCV RNA after 4 weeks) compared to peg-IFN and ribavirin alone. A trial evaluating 24 weeks of filibuvir in combination with peg-IFN and ribavirin has recently completed enrollment and data from this trial will be forthcoming.