SciClone Phase 3 ZADAXIN Triple Therapy Hepatitis C Trial in Europe.

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SAN MATEO, Calif.--(BUSINESS WIRE)--May 24, 2004

SciClone Pharmaceuticals, Inc. (Nasdaq:SCLN) today announced a multi-center phase 3 hepatitis C triple therapy clinical trial in Europe. SciClone's European marketing and development partner, Sigma-Tau, will conduct this Phase 3 multicenter, double blinded study in approximately 550 patients with chronic hepatitis C who are non-responders to prior pegylated interferon alpha and ribavirin therapy. The clinical trial will compare the triple combination therapy of ZADAXIN(R) (thymosin alpha 1), peginterferon alfa-2a (PEGASYS(R)) and ribavirin (COPEGUS(R)) to placebo, peginterferon alfa-2a (PEGASYS) and ribavirin (COPEGUS) to evaluate the benefit of adding ZADAXIN to current therapy for hepatitis C patients who have failed to respond to previous pegylated interferon alpha and ribavirin treatment. Patient enrollment is scheduled to commence in the fourth quarter of 2004.

"Together with Sigma-Tau, we have decided to initiate this major European multicentered, double blinded, placebo-controlled triple therapy clinical trial for the treatment of hepatitis C patients who have failed to respond to the current standard of care. The design of this study is based on the positive preliminary data from the pilot triple therapy study that is ongoing in Mexico," commented Donald R. Sellers, SciClone's Chief Executive Officer. "This trial is intended to complement our ongoing ZADAXIN plus peginterferon alfa-2a U.S. Phase 3 hepatitis C non-responder clinical trials. The objective of the European trial is to determine the possible incremental efficacy benefits of the ZADAXIN triple therapy compared to the current standard of care." The European trial will use Roche's PEGASYS brand of pegylated interferon, and COPEGUS brand of ribavirin. SciClone is providing ZADAXIN, up to $2.5 million of funding support for the trial and a $1.5 million milestone payment to Sigma-Tau at the completion of the study. SciClone has a European patent covering the use of ZADAXIN for the treatment of hepatitis C in non-responder patients in addition to the ZADAXIN European patent for use in the treatment of hepatitis C.

The clinical trial will be led by Prof. Mario Rizzetto, Professor of Gastroenterology University of Turin and will enroll patients who have not responded to prior therapy with pegylated interferon alpha plus ribavirin. All patients will receive 48 weeks of treatment with either ZADAXIN (1.6 mg twice a week), peginterferon alfa-2a (180 mcg once a week) and ribavirin (1,000 to 1,200 mg daily, according to body weight) or a placebo (twice a week), peginterferon alfa-2a (180 mcg once a week) and ribavirin (1,000 to 1,200 mg daily, according to body weight). After completing treatment, patients will be closely monitored for a 24-week observation period. The primary endpoint of the study is testing negative for HCV RNA, measured at 72 weeks, when patients have completed the observation period. The secondary endpoints are normalization of ALT (an enzyme present in the liver) measured at the end of weeks 48 and 72, HCV RNA negativity measured at the end of week 48, and improvement in the liver histological activity index.

Dr. Carminati, Director of Research and Development at Sigma-Tau, commented: "Hepatitis C patients who have failed standard therapy are a major un-met medical need and represent up to 50% of the original naive patients. We are very interested in exploring ZADAXIN's potential as a significant improvement for the treatment of these patients. Sigma-Tau's direct involvement in this European trial reinforces the Company's commitment to ZADAXIN development which spans from Hepatitis C to cancer immunotherapy." The ZADAXIN triple therapy hepatitis C clinical trial will be Sigma-Tau's second major clinical trial for ZADAXIN in Europe. Sigma-Tau is currently conducting a Phase 2 clinical trial studying the use of ZADAXIN in combination with standard chemotherapy for the treatment of malignant melanoma. Sigma-Tau's R&D activity is strongly focused on oncology as well as other major therapeutic fields such as infectious diseases and metabolic diseases.

Positive interim data from SciClone's ongoing pilot triple therapy clinical trial in hepatitis C non-responder patients were reported after 12 and 24 weeks of treatment with ZADAXIN, pegylated interferon alpha and ribavirin. After 24 weeks of triple therapy, 41% of patients tested HCV RNA negative and 50% of patients showed a virologic response. By comparison, separate studies show that after 24 weeks of standard therapy with pegylated interferon alpha and ribavirin, only approximately 30% of patients tested HCV RNA negative. With the planned initiation of the large European trial, the size of the study group for the Mexican pilot trial has been reduced to the 30 patients currently enrolled.

About SciClone

SciClone Pharmaceuticals is a biopharmaceutical company engaged in the development of therapeutics to treat life-threatening diseases. In addition to the phase 3 trial described today, SciClone is currently evaluating its lead product ZADAXIN in numerous other clinical trials, including two phase 3 hepatitis C clinical trials in the U.S., a completed phase 3 hepatitis B clinical trial in Japan, a phase 2 malignant melanoma clinical trial in Europe, two phase 2 liver cancer pilot studies in the U.S., a hepatitis C triple therapy open-label clinical trial in Mexico, and a hepatitis B combination therapy trial in Taiwan. The Company's other principal drug development candidate is SCV-07, a potentially orally available therapeutic to treat viral and infectious diseases. For more information about SciClone, visit www.sciclone.com.

About Sigma-Tau

Sigma-Tau is a leading research-based Italian pharmaceutical company with annual revenues in excess of $700 million and over 2300 employees worldwide. Therapeutic areas on which the company's research and development are focused include oncology, gastroenterology, neurology, cardiovascular, metabolism and immunology. Sigma-Tau has operating subsidiaries throughout Europe and the U.S. and maintains a presence in all of the world's major pharmaceutical markets. Press releases and corporate information from Sigma-Tau are available on the Internet at www.sigma-tau.it.

About Roche

Headquartered in Basel, Switzerland, Roche is one of the world's leading innovation-driven healthcare groups. Its core businesses are pharmaceuticals and diagnostics. Roche is number one in the global diagnostics market and is the leading supplier of pharmaceuticals for cancer and a leader in virology and transplantation. As a supplier of products and services for the prevention, diagnosis and treatment of disease, the Group contributes on a broad range of fronts to improving people's health and quality of life. Roche employs roughly 65,000 people in 150 countries. The Group has alliances and research and development agreements with numerous partners, including majority ownership interests in Genentech and Chugai.

This press release includes forward looking statements regarding our expectations for timing of events related to clinical trials. Actual timing and results could differ based on a number of factors, including delays in the trials due to slow enrollment, delays in our partners activities or other, unexpected events. The outcome of the trials can not be predicted and data from smaller studies may not be predictive of the outcome of larger trials.