ZADAXIN Demonstrates Significant Anti-Fungal Efficacy In Invasive Aspergillosis Animal Study 3/1/2004 SAN MATEO, Calif.--(BUSINESS WIRE)--March 1, 2004--SciClone Pharmaceuticals (Nasdaq:SCLN - News) today announced the publication of results from a new animal model study demonstrating, for the first time, that its lead drug candidate ZADAXIN® is an effective anti-fungal treatment for invasive aspergillosis. The study showed that ZADAXIN significantly contributed to the activation of the appropriate Th1 helper cells to combat the Aspergillus fungus through the use of toll-like receptors (TLRs), the first line of defense against invading infections. This study was conducted in Italy by a team led by Francesco Bistoni, M.D. and Luigina Romani, M.D. of the University of Perugia and Enrico Garaci, M.D. of the University of Tor Vergata in Rome. Dr. Garaci commented, "Thymosin alpha 1 (ZADAXIN) opens up a new frontier for the successful management of organ or bone-marrow transplantation and the treatment of immunodeficiency diseases. Since the Aspergillus fungus is the leading cause of infection in patients with suppressed immune systems, largely a result of receiving organ or bone marrow transplants or suffering from leukemia, there is now a real opportunity for an effective immune enhancing treatment for these patients." An immune suppressed mouse model was used to examine the effects of treating mice infected with the Aspergillus fungus with either ZADAXIN or the standard treatment of amphotericin B. Seven separate groups received the following treatments: untreated or placebo control; low, medium, and high dose ZADAXIN; amphotericin B; amphotericin B plus low dose ZADAXIN. Importantly, at the 60 day endpoint of the study, all of the mice that had received medium or high dose ZADAXIN alone were fully cured of invasive aspergillosis. Additionally, it was observed that low dose ZADAXIN, when used in combination with amphotericin B, was statistically significant in improving the efficacy of amphotericin B and increased the median survival rate from 11 days to 18 days. Untreated or placebo treated animals had a median survival of only 4 days. The investigators also evaluated the subcellular pathways involved in ZADAXIN's therapeutic effectiveness against Aspergillus. Dr. Cynthia Tuthill, Ph.D., SciClone's Vice President of Scientific Affairs, explained, "This study demonstrates that the mechanism of action of ZADAXIN includes in its pathway effects on toll-like receptors (TLRs) of the innate immune system, which highlights ZADAXIN's ability to affect both the innate arm of the immune system as well as its previously well documented effects on the adaptive immune system." The results of this study were recently published in Blood Online (www.bloodjournal.org) and showed increased survival and decreased lung pathology after treatment with ZADAXIN in a mouse model of invasive aspergillosis. About Aspergillus fumigatus The incidence of invasive aspergillosis has been steadily increasing over the past two decades and now represents the most common life-threatening fungal infection in the world. Mortality rates do vary, but can be as high as 95% in patients who have received allogeneic bone-marrow transplants and those with aplastic anemia. Left untreated, invasive aspergillosis most often proves to be fatal; however, if treatment is started early one third to one half of patients will survive. Aspergillus is a fungus that affects individuals with compromised immune systems, most often from disease or organ transplants. Aspergillus causes illness in three ways, the most serious being invasive aspergillosis that infects the lungs and can later spread through the bloodstream to other organs in the body.