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SciClone's Zadaxin Enhances H1N1 Vaccine in Critical First Six Weeks Post-Vaccination

SciClone and Sigma-Tau Announce Final Data from Clinical Trial of ZADAXIN as H1N1 Vaccine Enhancer

ZADAXIN Increases Seroconversion Rate in Critical First Six Weeks Following Vaccination

FOSTER CITY, CA – June 30, 2010 – SciClone Pharmaceuticals, Inc. (NASDAQ: SCLN) and its partner Sigma-Tau S.p.A., announced final results from a clinical study evaluating the potential of ZADAXIN® (thymalfasin) to enhance immune response to the MF59 adjuvanted H1N1 influenza monovalent vaccine, Focetria® from Novartis. As previously reported by investigators, ZADAXIN treatment given with the H1N1 vaccine led to statistically significant increases in the percentage of subjects who seroconverted when evaluated at both 21 days and 42 days after vaccination, as compared with vaccine alone. Seroconversion -- a significant rise in specific antibody titers against H1N1 influenza -- is defined as a four-fold or greater change in titers from baseline. A higher seroconversion rate is indicative of the robustness of a patient’s immune response. When evaluated at 84 and 168 days after vaccination, the seroconversion rates were similar for patients receiving ZADAXIN treatment and those receiving vaccine alone. These data indicate that the enhancement effect of ZADAXIN, while significantly higher in the critical first six weeks following vaccination, was reduced at later time points and no longer significantly different compared to the vaccine alone.

“We are pleased by the results of this study which demonstrate that ZADAXIN provides a significant and rapid enhancement benefit to the H1N1 vaccine during the critical first six weeks following vaccination,” said Israel Rios, MD, SciClone’s Senior Vice President and Chief Medical Officer. “Seroconversion during these early post-vaccination time points is crucial as it provides patients with a significant protective benefit. We believe this ability to trigger rapid seroconversion as compared to vaccine alone demonstrates the powerful benefit ZADAXIN may provide not only in combination with the H1N1 vaccine but with a variety of other important vaccines as well.”

Final data from the study showed that, when evaluated 84 days following vaccination, 60% of patients in the high-dose ZADAXIN arm achieved seroconversion, compared to 55% of patients in the vaccine-only arm of the study. For patients in the low-dose ZADAXIN arm, the rate was 46% at the 84 day mark. When evaluated 168 days following vaccination, 36% of patients in the high-dose ZADAXIN arm achieved seroconversion, compared to 29% of patients in the vaccine-only arm of the study. For patients in the low-dose ZADAXIN arm, the rate was 23% at the 168 day mark. These differences in seroconversion rates at days 84 and 168 were not statistically significant.

Previously reported data from the study showed that at 21 days following vaccination, 89% of patients in the high-dose ZADAXIN arm and 88% of patients in the low-dose ZADAXIN arm achieved seroconversion, as compared with only 56% who received vaccine alone. This increase for ZADAXIN was statistically significant (p value < 0.01) and compared favorably with that seen at 42 days following vaccination, which was reported as being 94% and 93% in the two ZADAXIN groups, compared to only 77% in patients treated with the vaccine alone. These 42-day data also represent a statistically significant increase (p value=0.04).

"Based on these promising study results and our belief that the beneficial effect of ZADAXIN may extend to vaccines targeting other types of infections and diseases, including cancer, we plan to continue our ongoing dialogue with bio-defense agencies and related groups to determine which vaccines they believe would benefit from enhancement,” said Friedhelm Blobel, PhD, SciClone’s President and Chief Executive Officer. “While our initial study of ZADAXIN as a vaccine enhancer focused on the H1N1 virus, we believe the product’s utility may extend well beyond this initial area of investigation.”

About Study Design

The randomized, three-arm open label study was designed to evaluate efficacy based on the proportion of patients achieving seroconversion. The study, which was conducted in patients with end-stage renal disease who are on chronic dialysis, included three cohorts. One cohort of patients received the H1N1 vaccine only and the other groups received ZADAXIN at either a low dose (3.2 mg) or a high dose (6.4 mg). ZADAXIN was given twice, the first injection seven days prior to vaccination and the second on the day of vaccination with Focetria. All patients who did not achieve an antibody titer of at least 1:40 on day 21 received a second H1N1 vaccination on that day. Dosing regimens were based on preclinical results obtained in ferret and mouse models conducted in Europe and the U.S.

ZADAXIN has an excellent safety profile, with a long track record of patient use. Approximately 100,000 patients worldwide have used ZADAXIN in both commercial and clinical 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 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 allow the immune system to tag and identify infected and cancerous cells for removal.

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. In general, ZADAXIN was safe and well tolerated.

About SciClone

SciClone Pharmaceuticals (NASDAQ: SCLN) is a profit-focused, 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 vaccines; SCV-07 in a phase 2 trial for the delay to 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, including Hong Kong and Macau, 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. Sigma-Tau website:

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 and our partner’s ability to determine and effectively initiate and conclude a development plan for H1N1. 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.

Focetria is a registered trademark of Novartis AG Corporation.

DC Bead is a registered trademark of Biocompatibles UK Limited.

RapidFilm is a trademark of Labtec Gesellschaft für technologische Forschung und Entwicklung mbH.



Posted: June 2010