ANA598 Shows Positive Results In Animal Model Of Chronic Hepatitis C Virus Infection

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Anadys Pharmaceuticals announced preliminary data from two studies of ANA598, a non-nucleoside inhibitor of the hepatitis C virus (HCV) NS5B polymerase, in a primate model of chronic HCV infection.

Two animals chronically infected with HCV genotype 1b each received once-daily oral doses of ANA598 at 30 mg/kg for four days. A rapid viral load decline was seen in both animals. At 48 hours (24 hours after the second dose), viral load declines were 2.2 and 2.6 log10 in the individual animals. In one animal the viral load reduction was sustained throughout the remaining dosing period, while in the second animal a modest rise in viral load was seen over days 3 and 4, although the rise observed (0.6 log10) was within the baseline variability seen in this animal prior to dosing.

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In a previous study conducted to assess the pharmacokinetics (PK), safety, tolerability and preliminary antiviral activity of ANA598, two HCV genotype 1a infected animals received a single oral dose of ANA598 at 30 mg/kg. At 24 hours after dosing, plasma levels of ANA598 exceeded the replicon EC95 values. At 48 hours after dosing, the mean viral load decline in the two animals was 1.0 log10. ANA598 was well tolerated by all of the animals in both studies.

"These positive animal efficacy data reinforce our continued enthusiasm for development of ANA598 as a potential new direct antiviral treatment for chronic HCV," said Steve Worland, Ph.D., President and Chief Executive Officer of Anadys. "The rapid viral load decline and the favorable PK, safety and tolerability profile demonstrated in these animal efficacy studies further support continued development of ANA598 as a candidate for use in combination with other agents for the treatment of chronic HCV infection."

In June 2007, Anadys announced the nomination of ANA598 as a clinical development candidate. The selection of ANA598 represented the culmination of a comprehensive structure-based drug design program directed towards NS5B. ANA598 was selected based on an optimized balance of preclinical properties, including intrinsic potency as an NS5B inhibitor, cellular activity in the replicon assay, oral bioavailability and early indicators of safety and tolerability. ANA598 is a low-nanomolar inhibitor of HCV genotype 1a and 1b replicons. It exhibits good in vitro metabolic stability properties and does not significantly inhibit or induce cytochrome P450 enzymes. In vivo, ANA598 was well tolerated in 14-day dose range finding (DRF) animal toxicology studies. At doses corresponding to estimated human doses, 24 hour trough plasma concentrations of ANA598 exceeded the EC95 for HCV genotype 1a and 1b replicon inhibition. The EC95 is the concentration required in vitro to suppress hepatitis C viral RNA levels by 95% in the replicon assay.

ANA598 is currently completing IND enabling activities and an IND submission is targeted for the second quarter of 2008. "After completing the necessary IND enabling studies, we look forward to exploring the potential clinical utility of ANA598," said James Freddo, MD, Anadys' Chief Medical Officer. "Based on the in vitro and in vivo potency, pharmacokinetic and preliminary toxicologic properties of ANA598 demonstrated to date, we believe that this is an exciting new direct antiviral to investigate for the treatment of patients with hepatitis C virus infection."

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