Pharmasset Reports Preliminary Results of a 4-week Combination Study of R7128 for the Treatment of Chronic H...( - 88% of patients achieve undetectab...),Health

- 88% of patients achieve undetectable HCV RNA levels following 4 weeks of

treatment with R7128 1000mg BID with Pegasys(R) plus Copegus(R) - - Safety and tolerability comparable to placebo administered with Pegasys

plus Copegus -

PRINCETON, N.J., Aug. 5 /PRNewswire-FirstCall/ -- Pharmasset, Inc. (Nasdaq: VRUS) announces the preliminary results of the third cohort of a 4-week Phase 1 clinical trial evaluating R7128 1000mg twice daily (BID) in combination with the standard of care (SOC), Pegasys(R) (pegylated interferon) plus Copegus(R) (ribavirin), in 31 treatment-naive patients chronically infected with hepatitis C virus (HCV) genotype 1. R7128, a prodrug of PSI-6130, is a nucleoside analogue polymerase inhibitor of HCV that is being developed in collaboration with Roche.

As previously reported for Cohorts 1 and 2 of this study, R7128 has demonstrated potent short-term antiviral activity and was generally safe and well tolerated at doses of 500mg and 1500mg administered for 28 days in combination with SOC. In Cohort 3, a new formulation of R7128 1000mg BID was administered in combination with SOC. Of the 31 patients enrolled, 25 patients received R7128 1000mg BID and 6 received placebo. 88% (22 of 25) patients receiving R7128 1000mg BID with SOC for 4 weeks achieved undetectable HCV RNA levels (<15 IU/mL). This high rate of Rapid Virologic Response (RVR) compares favorably with the 85% RVR demonstrated earlier this year with R7128 1500mg BID in combination with SOC. Based on these results, R7128 1000mg BID will be among the doses carried forward into Phase 2b studies, which we expect to be submitted to the FDA this Fall.

The preliminary safety and tolerability of R7128 1000mg BID
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