SciClone, Sigma-Tau Announce Preliminary Results in Study Examining Zadaxin's Ability to Enhance Response to H1N1 Vaccine

SciClone and Sigma-Tau Announce Positive Preliminary Results in Clinical Study Examining Zadaxin's Ability to Enhance Response to H1N1 Vaccine
Study Shows Increase In Seroconversion From 56% To 88% 21 days after vaccination
FOSTER CITY, CALIF., and ROME, ITALY - January 12, 2010 -- SciClone Pharmaceuticals, Inc. (NASDAQ: SCLN) and its partner Sigma-Tau S.p.A., have received initial topline results in a clinical study evaluating the potential of ZADAXIN® (thymalfasin) to enhance immune response to the MF59 adjuvanted H1N1 influenza monovalent vaccine, FocetriaTM from Novartis. According to investigators, ZADAXIN treatment given with the H1N1 vaccine led to a highly statistically significant (p value<0.01) increase in the percentage of subjects who seroconverted at 21 days after vaccination, when compared to those who received the H1N1 vaccine alone. Seroconversion is defined as a four or greater change in titers from baseline.
The randomized, three-arm open label study has a planned duration of 6 months and hence is still ongoing. It is being conducted in patients with end-stage renal disease who are on chronic dialysis. One cohort of patients received the H1N1 vaccine only, while the other two groups received either two 3.2 mg injections of thymalfasin (one seven days prior to vaccination and the second on the day of vaccination with Focetria), or two 6.4 mg injections of thymalfasin (one seven days prior to vaccination and the second on the day of vaccination with Focetria). Dosing regimens were based on preclinical results obtained in ferret and mouse models conducted in Europe and the U.S. earlier this year.
This ongoing study is designed to evaluate efficacy based on the proportion of patients achieving seroconversion - a significant rise in specific antibody titers against H1N1 influenza. According to investigators, at 21 days following vaccination, 89% of patients in the low-dose ZADAXIN arm achieved seroconversion as did 88% of patients in the high-dose ZADAXIN arm, compared to only 56% of patients in the vaccine-only arm of the study. All patients are being followed for six months, to measure the durability of the protective titers, the second key parameter for the assessment of the immunogenicity of a vaccination. A higher seroconversion rate is indicative of the robustness of the immune response and may lead to more durable protection.
"We believe the rapid achievement of full enrollment in this study indicates the need for safe and effective vaccine enhancers to help protect immune compromised and elderly patients from H1N1 influenza," said Prof Trevor Jones, Group R&D Director, Sigma-Tau. "Given the complexities in treating those with compromised or weakened immune systems, we believe these are the patients most in need of protection from life-threatening virus infections such as H1N1."
"We are encouraged by the results of the study which, for the first time, used less frequent injections of ZADAXIN at the higher dose formulation," said Friedhelm Blobel, Ph.D. SciClone's President and Chief Executive Officer. "We hope that this pilot study will be completed successfully and that we can proceed thereafter with applications for  regulatory approval regarding the use of ZADAXIN as enhancer for vaccinations for H1N1 influenza using a one or two shot dosing regime. We have obtained regulatory approval for ZADAXIN for use as an adjuvant for regular influenza in more than 10 countries using multiple injections."
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 immune responses. Published scientific and clinical studies have shown that thymalfasin helps stimulate and direct the body's immune system to improve response to vaccines, and to eradicate infectious diseases like HCV and HBV, as well as certain cancers.
Within the immune system, thymalfasin stimulates stem cell differentiation and increases production of antibodies and disease-fighting T cells, including CD4, CD8, and natural killer cells, while simultaneously slowing the breakdown and removal of these T cells. The increase in production of antibodies after thymalfasin treatment leads to an increase in response to vaccines, providing enhanced protection against infection; the increases in T-helper cells allows the immune system to tag and identify invasive agents and cancerous cells for removal.
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 1 and 2 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 studies, more than 4,000 patients being treated with vaccines or infected with viral hepatitis B or hepatitis C, primary immunodeficiency diseases, or various 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 clinical 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 BeadTM in China, where the product is under regulatory review. The Company also has exclusive commercialization and distribution rights to the anti-nausea drug ondansetron RapidFilmTM in China and Vietnam, for which it will seek regulatory approval. For additional information, please visit
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.
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Forward-Looking Statements
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