Pharmasset Commences Dosing in Phase 3 Registration Studies of Clevudi...( -Two 48-week Superiority Studies vers...),Health

-Two 48-week Superiority Studies versus Hepsera(R) in Patients with Chronic

Hepatitis B- -Studies will also Assess Clevudine's Sustained Virologic Response Rate for

HBV-

PRINCETON, N.J., Oct. 1 /PRNewswire-FirstCall/ -- Pharmasset, Inc. (Nasdaq: VRUS) has commenced dosing in Phase 3 registration clinical trials of clevudine for the treatment of chronic hepatitis B virus (HBV) infection. Clevudine is an oral, once-daily pyrimidine nucleoside analog that has previously been evaluated in 14 clinical trials in more than 800 individuals. The current Phase 3 studies will be conducted in 856 nucleoside treatment- naive patients with chronic HBV at approximately 140 global clinical sites to support the registration of clevudine in the Americas and Europe. Pharmasset licensed these territories from Bukwang Pharmaceuticals, who recently received South Korean regulatory approval and began marketing clevudine in South Korea under the brand name Levovir. As a result of the initiation of these studies, Pharmasset will pay Bukwang a $1.0 million milestone payment.

"Based upon prior 24 week treatment results, we are optimistic that clevudine will demonstrate superiority to Hepsera in its ability to suppress HBV DNA and normalize liver enzyme levels after 48 weeks of treatment," stated Dr. Michelle Berrey, Pharmasset's Vice President, Clinical Development & Chief Medical Officer. "We also expect to build upon the results from earlier studies that demonstrated clevudine's ability to provide a sustained virologic response, or SVR, for chronic HBV infection. If we are able to demonstrate SVR for HBV in these studies, clevudine could offer patients and their
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