Pharmasset Presents R7128 Phase 1 Single Ascending Dose Study in Healthy ...(ending dose study of R7128 conducted in ...),Health

healthy volunteers. The primary objective of Part 1 is to assess the

safety, tolerability and pharmacokinetics of R7128 following single

ascending doses under fasting conditions. The secondary objective of

Part 1 is to explore the effect of food on the pharmacokinetics of

R7128. Preliminary data from the single ascending dose portion of the

study indicate:

- All doses of R7128 studied were generally safe and well-tolerated.

- All patients completed the study, and none experienced

gastrointestinal adverse events or serious adverse events during

the study.

- No hematological or laboratory abnormalities of clinical

significance were noted.

- Part 2 is a multiple ascending dose study of R7128 conducted in 40

patients chronically infected with HCV genotype 1 who have previously

failed interferon therapy. The primary objective of Part 2 is to

assess the safety, tolerability and pharmacokinetics of R7128 after

once-daily or twice-daily dosing for 14 days. The secondary objective

is to assess antiviral activity by measuring the change in HCV RNA.

About Hepatitis C

Hepatitis C is a blood-borne infectious disease of the liver and is a leading cause of chronic liver disease and liver transplants. The World Health Organization estimates that nearly 180 million people worldwide, or approximately 3% of the world's population, are infected with hepatitis C virus (HCV). The CDC has reported that almost four million people in the United States have been infected with HCV, of whom 2.7 million are chronically infected.

Contact

Alan Roemer, Vice President

Investor Relations & Corporate Communications

alan.roemer@pharmasset.com

Office: (609) 613-4125

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