Pharmasset Presents R7128 14-Day Monotherapy Study Results for the Treatment of Chronic H...( -Nucleoside polymerase inhibitor demo...),Health

-Nucleoside polymerase inhibitor demonstrates >99% mean decrease in HCV RNA

with no serious adverse events-

PRINCETON, N.J., Nov. 2 /PRNewswire-FirstCall/ -- Pharmasset, Inc. (Nasdaq: VRUS) announces the results of a 14-day Phase 1 multiple ascending dose monotherapy study of R7128 for the treatment of chronic hepatitis C infection. In this study, being presented as a "late-breaker" abstract at the 58th Annual Meeting of the American Association for the Study of Liver Diseases, R7128 demonstrated potent antiviral activity and was generally safe and well-tolerated. R7128 is an orally administered prodrug of PSI-6130, a cytidine nucleoside analogue polymerase inhibitor of hepatitis C virus (HCV) that is being developed through Pharmasset's collaboration with Roche.

"R7128 has provided positive proof-of-concept that a single, direct-acting antiviral can deliver sufficient potency to suppress HCV in an interferon non- responder population," stated Dr. Michelle Berrey, Pharmasset's Vice President, Clinical Development & Chief Medical Officer. "Since robust synergy has been observed with other potent inhibitors when combined with the standard of care for HCV, we hope that these monotherapy results will translate well when R7128 is used with standard of care for longer duration in a treatment-naive population."

Dr. Rajender Reddy, Professor of Medicine and Surgery in the Division of Gastroenterology at the University of Pennsylvania and a clinical investigator in the study, noted "R7128's safety profile is encouraging, with no serious or treatment-limiting adverse events reported even at the highest dose tested. In addition, there were actually a higher number of adverse events reported
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