Pharmasset Announces R7128 Achieves 85% Rapid Virologic Response in a 4-week Combination Study for the Treatment of Chronic H...( - 85% of patients achieve undetectab...),Health

- 85% of patients achieve undetectable HCV RNA levels following 4 weeks of treatment with R7128 1500mg and Pegasys(R) plus Copegus(R) with safety and

tolerability comparable to placebo -

- Conference Call Scheduled for 4:00PM ET Today -

PRINCETON, N.J., Jan. 7 /PRNewswire-FirstCall/ -- Pharmasset, Inc. (Nasdaq: VRUS) announces the preliminary results of a 4-week Phase 1 clinical trial to evaluate two oral dose levels of R7128 in combination with Pegasys (pegylated interferon) plus Copegus (ribavirin) in 50 treatment-naive patients chronically infected with hepatitis C virus (HCV) genotype 1. In this study, R7128 demonstrated potent short-term antiviral activity and was generally safe and well-tolerated. Eighty-five (85%) of patients receiving R7128 1500mg and Pegasys plus Copegus achieved undetectable HCV RNA levels following 4 weeks of treatment with safety and tolerability comparable to placebo. R7128 is a prodrug of PSI-6130, a cytidine nucleoside analogue polymerase inhibitor of HCV that is being developed through Pharmasset's collaboration with Roche.

Dr. Michelle Berrey, Pharmasset's Chief Medical Officer, stated "R7128, in combination with Pegasys plus Copegus, has shown that nucleoside polymerase inhibitors can demonstrate Rapid Virologic Response (RVR) percentages that are similar to protease inhibitors with an acceptable short-term clinical safety profile. This study also suggests that there appear to be certain synergies between nucleoside polymerase inhibitors and the standard of care that is not found with other classes of HCV inhibitors. The addition of R7128 at both dose levels to the current standard of care has demonstrated a greater percentage of RVR compared to the standa
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