Pharmasset Reports Preliminary Results of a 4-week Proof-of-Concept Combination Study of R7128 for the Treatment of Chronic Hepatitis C in Genotype 2 or 3 Non-...( - 90% of genotype 2 or 3 patients ...)

- 90% of genotype 2 or 3 patients achieve undetectable HCV RNA levels following 4 weeks of treatment with R7128 1500mg BID with Pegasys(R) plus

Copegus(R) - - Safety and tolerability comparable to placebo administered with Pegasys

plus Copegus -

PRINCETON, N.J., Sept. 8 /PRNewswire-FirstCall/ -- Pharmasset, Inc. (Nasdaq: VRUS) announces the preliminary results of the fourth cohort of a 4-week Phase 1 proof-of-concept clinical trial evaluating R7128 1500mg twice daily (BID) in combination with the standard of care (SOC), Pegasys(R) (pegylated interferon) plus Copegus(R) (ribavirin) in 20 patients chronically infected with hepatitis C virus (HCV) genotype 2 or 3 who had not achieved a Sustained Viral Response (SVR) with prior SOC therapy. R7128, a prodrug of PSI-6130, is a nucleoside analogue polymerase inhibitor of HCV that is being developed through Pharmasset's collaboration with Roche.

In this study, preliminary results indicated that R7128 demonstrated significant short-term antiviral activity in patients who were previous non-responders or relapsers to treatment and was generally safe and well tolerated. Of the 25 patients enrolled, 20 patients received R7128 1500mg BID and 5 received placebo. Patients receiving R7128 1500mg BID with SOC for 4 weeks achieved a mean 5.0 log10 HCV RNA decline and 90% (18 of 20) achieved undetectable (<15 IU/ml) HCV RNA levels (RVR). Patients receiving placebo with SOC for 4 weeks achieved a mean 3.7 log10 HCV RNA decline and 60% (3 of 5) achieved an RVR. These viral load reductions for patients with genotype 2 or 3 are similar to those reported earlier for patients with genotype 1 treated with 1000mg BID and 1500mg BID and
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