Pharmasset, Inc. And Bukwang Announce Clevudine Hepatitis B Presentation At EASL

PRINCETON, N.J. and SEOUL, South Korea, April 27 /PRNewswire/ -- Pharmasset and Bukwang announced today that a presentation of the preliminary results of a Korean Phase III clinical trial of Clevudine for the treatment of Hepatitis B will be made during the 41st Annual Meeting of the European Association for the Study of the Liver (EASL) being held in Vienna, Austria from April 26-30, 2006. Dr. Young Hwa Chung of the Department of Medicine at Asan Medical Center, Ulsan University in Seoul, South Korea will present 48- week clinical data, entitled "One-year treatment with Clevudine demonstrated significant viral suppression and biochemical improvement," on Friday, April 28, 2006 at 5:45pm (CEST) during EASL's Parallel Session 5: Hepatitis B Disease and Therapy.

The goal of this late-stage clinical trial, Study 303, was to evaluate the safety, antiviral activity, biochemical improvement, and serologic response in patients treated with Clevudine. Although Clevudine's commercial dosing regimen is anticipated to be 30 mg per day for the entire duration of treatment, Study 303 used a dosing regimen of 30 mg of Clevudine for 24 weeks followed by 10 mg of Clevudine for an additional 24 weeks as a maintenance therapy. The results to be presented are derived from 55 treatment-naive patients (40 HBeAg+ and 15 HBeAg-) who have completed the treatment phase of the study. At week 48, 68% of HBeAg+ and 100% of HBeAg- patients were PCR negative (<300 copies/ml) for HBV DNA, and 89% of HBeAg+ and 100% of HBeAg- patients had normal alanine aminotransferase (ALT) levels. At week 48, serum HBeAg loss occurred in 16% of patients and HBeAg seroconversion occurred in 14% of HBeAg+ patients. No serious adverse events were observed, and adverse events were mild and transient.

"As previously observed in Study 301 and Study 302, the Study 303 results continue to demonstrate that Clevudine has several potential advantages over existing small molecule therapies for the treatment of Hepatitis B," stated Schaefer Price, Pharmasset's President & CEO. "At 48 weeks, we believe that the percentage of patients with undetectable virus and the percentage of patients with normal ALT levels compare favorably to previously published data from the registration studies of existing HBV therapies. We look forward to initiating our two Phase III global registration studies for Clevudine, in which we intend to treat patients with the anticipated commercial dose of 30 mg for the entire 48 week duration of the studies in comparison to a currently approved HBV therapy."

Clevudine, an investigational agent, is a pyrimidine nucleoside analog that has shown potent anti-HBV activity in both preclinical studies and clinical trials in over 600 HBV-infected patients. Clevudine is not an HBV DNA chain terminator like existing nucleoside analog drugs for the treatment of Hepatitis B. In contrast, the active form of Clevudine acts directly on the HBV polymerase to reduce its ability to incorporate nucleosides into new viral DNA chains. In preclinical animal models, Clevudine has demonstrated the ability to significantly reduce covalently closed circular DNA, or cccDNA, which is believed to be responsible for the persistence of an HBV infection. In previous Korean Phase III clinical trials, 24 weeks after the cessation of treatment with Clevudine, the average viral load for patients remained statistically significantly lower than the average viral load for patients who had received placebo.

Pharmasset, Inc. is a clinical stage pharmaceutical company committed to the discovery and development of novel drugs to treat viral infections. Our primary focus is on the development of nucleoside analog drugs for the treatment of human immunodeficiency virus, or HIV, hepatitis B virus, or HBV, and hepatitis C virus, or HCV. We currently have three product candidates: Clevudine in late-stage clinical trials for the treatment of chronic Hepatitis B; Racivir(R) in Phase 2 clinical trials for the treatment of HIV; and PSI- 6130 and its prodrugs for the treatment of Hepatitis C. We are applying our expertise in nucleoside chemistry to the discovery and development of additional antiviral therapeutics.

In June 2005, Pharmasset entered into an exclusive license agreement with Bukwang Pharm. Co., Ltd. to develop and commercialize Clevudine for the treatment of Hepatitis B in certain territories, including the United States, Europe, and South America. In 2004, Pharmasset entered into a collaboration agreement with Hoffmann-La Roche for the development and commercialization of PSI-6130 and its prodrugs for the treatment of Hepatitis C in certain territories. Pharmasset retains proprietary development and commercialization rights to the balance of its clinical and preclinical pipeline.

For more information, please visit http://www.pharmasset.com.

Bukwang Pharm. Co., Ltd. is a pharmaceutical, oral hygiene, and cosmetics company based in Seoul, South Korea that is listed on the Korean Stock Exchange [KRX: 003000]. Bukwang's sales are primarily derived from products licensed from Europe, the United States, and Japan. The company is currently investing significant resources in R&D to create a robust pipeline of preclinical and clinical agents for the treatment of antiviral diseases, diabetic neuropathy, and cancer. With a vision of delivering better human healthcare products, Bukwang has expanded its R&D activities through its subsidiary, Anterogen Co., Ltd., which focuses on adult stem cell research for heart tissue regeneration from bone marrow derived stem cells.

STATEMENTS IN THIS COMPANY PRESS RELEASE MAY CONSTITUTE FORWARD-LOOKING STATEMENTS AND ARE SUBJECT TO NUMEROUS RISKS AND UNCERTAINTIES, INCLUDING THE FAILURE OF CLEVUDINE TO PERFORM AS EXPECTED, THE COMPANY'S ABILITY TO ATTRACT AND RETAIN QUALIFIED PERSONNEL TO CONDUCT THE REQUIRED CLINICAL TRIALS OF CLEVUDINE , THE COMPANY'S FUTURE CAPITAL NEEDS TO FUND THE CLEVUDINE DEVELOPMENT PROGRAMS, THE COMPANY'S ABILITY TO OBTAIN ADDITIONAL FINANCING, THE COMPANY'S ABILITY TO OBTAIN REQUIRED REGULATORY APPROVALS FOR CLEVUDINE, THE DEVELOPMENT OF COMPETITIVE HBV PRODUCTS BY OTHERS, THE EXISTENCE OF THIRD- PARTY PATENT RIGHTS, AND OTHER RISKS INHERENT IN DISCOVERY AND DEVELOPMENT STAGE PROGRAMS AT A BIOTECHNOLOGY COMPANY. THE ACTUAL RESULTS FOR CLEVUDINE MAY DIFFER MATERIALLY FROM THOSE ANTICIPATED IN THIS COMPANY PRESS RELEASE. THE COMPANY DISCLAIMS ANY OBLIGATION TO UPDATE THE STATEMENTS CONTAINED IN THIS COMPANY PRESS RELEASE.

Contact: Alan Roemer

+1 (609) 613-4125 alan.roemer@pharmasset.com

CONTACT: Alan Roemer of Pharmasset, +1-609-613-4125 oralan.roemer@pharmasset.com

Web site: http://www.pharmasset.com//