SciClone Pharmaceuticals, Inc. Announces Commencement and Complete Enrollment of Clinical Study Examining ZADAXIN's Ability to Enhance the H1N1 Vaccine Led by European Partner, Sigma-Tau Group

FOSTER CITY, CA--(Marketwire - November 30, 2009) - SciClone Pharmaceuticals, Inc. (NASDAQ: SCLN) today announced that Rome-based development partner Sigma-Tau, S.p.A., has initiated a pilot study in Italy to evaluate ZADAXIN's® (thymalfasin) ability to enhance immune response to the MF59 adjuvanted H1N1 influenza monovalent vaccine, Focetria™ from Novartis. The study, being conducted in hemodialysis patients, is now completely enrolled, having reached full enrollment after two days. Top-line clinical results are expected by late 2009 or early 2010.

SciClone and Sigma-Tau conducted preclinical studies earlier this year to demonstrate the potential of ZADAXIN to enhance the immune response to H1N1 pandemic flu vaccines. Preclinical studies including one with ferrets demonstrated the feasibility of ZADAXIN to fit into the one or two dosing regimens of such vaccines.

The randomized, three-arm open study is being conducted in approximately 120 patients with end-stage renal disease who are on chronic dialysis. One cohort of patients will receive the H1N1 vaccine only, while the other two groups will receive either two low-dose injections of thymalfasin (3.2mg seven days prior to vaccination and on the day of vaccination), or two higher dose injections of thymalfasin (6.4mg seven days prior to vaccination and on the day of vaccination). Dosing regimens are based on preclinical results obtained in ferret and mouse models conducted in Europe and U.S. earlier this year.

The primary efficacy endpoint is the proportion of patients who achieve seroconversion (significant rise in specific antibody titers believed to be protective). Additionally, patients will be followed for six months to assess the durability of the protective titers.

"Patients with end-stage renal disease requiring hemodialysis and other conditions which compromise the immune system, as well as the elderly, can often have difficulty developing sufficient antibodies to fight off infectious diseases such as H1N1 influenza. Equally important, many patients who do achieve protective titers initially are unable to sustain these for longer periods of time, making them susceptible to infection and requiring revaccination or booster shots," said Professor Roberto Gasparini, MD, Department of Health Sciences, Section of Hygiene & Preventive Medicine, University of Genoa. "We are encouraged by thymalfasin's ability to increase antibody production in light of the preclinical studies results, while possibly sustaining this response for longer periods of time. We hope that this clinical trial will show that thymalfasin can be a safe and effective tool to help protect vulnerable patients from the potential life-threatening effects of the H1N1 virus."

"ZADAXIN is currently approved in Italy and more than 10 other countries as an enhancer for the influenza vaccine in immune-compromised patients," said Friedhelm Blobel, Ph.D. SciClone's President and Chief Executive Officer. "We are confident that ZADAXIN's immune-stimulating properties will help these patients maximize the immunogenic effects of the H1N1 vaccine and help fight off this pandemic virus."

Previous studies examining the use of ZADAXIN to enhance seasonal influenza vaccines for hemodialysis patients showed that 65% of patients receiving ZADAXIN enhancer achieved protective antibody response, versus 24% of those who received the vaccine alone. A similar study in 330 elderly patients showed a 70% protective antibody response rate among those receiving ZADAXIN plus influenza vaccine, versus 35% of those who received the vaccine alone. ZADAXIN was also shown to decrease the incidence of influenza in these elderly patients. According to a study published in The Gerontologist, 19% of patients who received the vaccine alone developed influenza, while only 6% of those who also received ZADAXIN became infected.

ZADAXIN has an excellent safety profile, with a long track record of patient use. Approximately 100,000 patients worldwide have used ZADAXIN in both clinical and commercial settings, alone and in combination with various antiviral and anticancer drugs.

About thymalfasin (ZADAXIN)

ZADAXIN, scientifically referred to as thymalfasin or thymosin alpha 1, is SciClone's synthetic preparation of thymalfasin, a peptide produced by the thymus gland which circulates in the blood naturally, and is instrumental in the immune response to certain cancers and viral infections. Published scientific and clinical studies have shown that thymalfasin helps stimulate and direct the body's immune response to eradicate infectious diseases like HCV and HBV, as well as certain cancers.

Thymalfasin works by stimulating a number of immune system responses and also elicits direct antiviral and anti-cancer effects. Within the immune system, thymalfasin stimulates stem cell differentiation and increases production of disease-fighting T cells, including CD4, CD8, and natural killer cells. Simultaneously it slows the breakdown and removal of these T cells. It also increases production of T-helper cells which allow the immune system to tag and identify invasive agents. Thymalfasin increases the production of proteins that stimulate T cell creation while decreasing production of certain proteins which are counterproductive in the fight against chronic viral infections. Additionally, thymalfasin helps dramatically slow down viral replication, allowing the strengthened immune system to more efficiently destroy virally infected cells.

In late 2008, SciClone and the FDA reached agreement in form of a Special Protocol Assessment on the design of a phase 3 registration trial for thymalfasin as a potential treatment for stage IV melanoma. Thymalfasin's potential beneficial role in treatment of melanoma derives from its demonstrated activation of the immune system through effects on Toll-like receptor 9 and signaling through increases in the nuclear factor NfKB, leading to increases in tumor-infiltrating lymphocytes, specific anti-tumor cytotoxic lymphocytes, and expression of MHC Class cell-surface molecules. Evaluation of thymalfasin's utility in melanoma animal models has confirmed effective anti-tumor activity.

ZADAXIN is currently approved in more than 30 countries worldwide to treat a variety of indications. In clinical and non-clinical studies, more than 4,000 patients with viral hepatitis B and hepatitis C, primary immunodeficiency diseases, and numerous cancers have been treated with ZADAXIN with virtually no drug-related side effects.

About SciClone

SciClone Pharmaceuticals (NASDAQ: SCLN) is a profit-driven, global specialty pharmaceutical company with a substantial international business and a product portfolio of novel therapies for cancer and infectious diseases. SciClone is focused on continuing international sales growth, a cost-containing clinical development strategy, and overall expense management. ZADAXIN® (thymalfasin or thymosin alpha 1) is sold in over 30 countries for the treatment of hepatitis B (HBV) and hepatitis C (HCV), certain cancers and as a vaccine adjuvant. SciClone's pipeline of drug candidates includes thymalfasin, in preclinical studies as an enhancer of H1N1 flu vaccines; thymalfasin for stage IV melanoma, for which SciClone has reached agreement with the FDA on the design of a phase 3 trial; SCV-07 in a phase 2 trial for the delay of onset of severe oral mucositis in patients receiving chemoradiation therapy for the treatment of cancers of the head and neck; and SCV-07 in a phase 2 trial for the treatment of HCV. SciClone has exclusive commercialization and distribution rights to DC Bead™ in China, where the product is under regulatory review. The Company also has exclusive commercialization and distribution rights to the anti-nausea drug ondansetron RapidFilm™ in China and Vietnam, for which it will seek regulatory approval. For additional information, please visit www.sciclone.com.

About sigma-tau

sigma-tau is a leading, international, pharmaceutical group that invests in the research, development and marketing of innovative and effective treatments to improve patient well-being and quality of life. sigma-tau has its headquarters in Pomezia (Rome, Italy). A total of 13 NCEs and 12 known molecular entities in 33 different indications are at various stages of development. Among them, several are aimed at rare diseases. Therapeutic areas in which the company's research and development are focused include metabolism, neurology, cardiovascular, oncology and immunology.

sigma-tau website: www.sigma-tau.it

Forward-Looking Statements

This press release contains forward-looking statements regarding development objectives and timing expectations. You are urged to consider statements that include the words "may," "will," "would," "could," "should," "might," "believes," "estimates," "projects," "potential," "expects," "potential," "plans," "anticipates," "intends," "continues," "forecast," "designed," "goal," or the negative of those words or other comparable words to be uncertain and forward-looking. These statements are subject to risks and uncertainties that are difficult to predict and actual outcomes may differ materially. These risks and uncertainties include our ability to conclude the clinical trial described in this press release and demonstrate a meaningful therapeutic effect for the indicated usage without significant adverse affects in the patient population. Please also refer to other risks and uncertainties described in SciClone's filings with the SEC. All forward-looking statements are based on information currently available to SciClone and SciClone assumes no obligation to update any such forward-looking statements.