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| HUMAN GENOME SCIENCES RECEIVES FDA CLEARANCE TO INITIATE HUMAN TRIAL OF NOVEL DRUG TO PREVENT AND TREAT ANTHRAX INFECTIONS | |
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- A single dose protects animals from the lethal effects of anthrax spores - - Protective effect is immediate following achievement of appropriate blood levels of the new human monoclonal antibody - ROCKVILLE, Maryland -- June 25, 2003 -- Human Genome Sciences, Inc. (Nasdaq: HGSI) announced today that it has received clearance from the U.S. Food and Drug Administration (FDA) of its Investigational New Drug (IND) application to begin human trials of ABthrax™, a novel drug for the prevention and treatment of anthrax infections. The Company has received clearance to begin enrolling healthy adult volunteers into a Phase 1 placebo-controlled, dose-escalation clinical trial to evaluate the safety, tolerability and pharmacokinetics of ABthrax. Healthy adults will be enrolled to evaluate different dose levels of intramuscularly administered ABthrax and intravenously administered ABthrax. Large-scale development and manufacture of ABthrax is dependent on government funding either under existing authority or under proposed Project Bioshield legislation. ABthrax is a human monoclonal antibody to Bacillus anthracis protective antigen that was discovered and developed by Human Genome Sciences. ABthrax has been shown to be effective in protecting against anthrax in multiple experimental models in animals. A single dose of ABthrax increases survival significantly in both rabbit and nonhuman primate models of inhalational anthrax.1 Human Genome Sciences plans, subject to government funding, to develop ABthrax for use as a prophylactic and therapeutic drug to prevent and treat anthrax infections. ABthrax used for preclinical and clinical studies is produced in the Company’s manufacturing facilities in Rockville, Maryland. Under the Bioterrorism Act of 2002, the FDA specified the evidence required to demonstrate the efficacy of new drug and biological products used to counter biological agents, when traditional efficacy studies in humans are not feasible.2 According to the guidelines set forth in the Bioterrorism Act, successful studies in relevant animal models will be considered sufficient to establish efficacy for licensure and marketing approval. ABthrax has been demonstrated to be effective in preventing the lethal effects of anthrax infection in two relevant models, rabbits and nonhuman primates. According to the guidelines, clinical trials will be required to establish safety, tolerability, and pharmacology, but not efficacy. Human Genome Sciences now plans to proceed with a Phase 1 human trial to establish the safety, tolerability, and pharmacology of ABthrax in healthy adults. Results from preclinical studies conducted to date demonstrate that a single dose of ABthrax administered prophylactically increases survival significantly in both rabbits and nonhuman primates exposed by inhaling lethal doses of anthrax spores. In both models, an absence of bacteria in the blood of all ABthrax-treated animals that survived was observed. The rabbit and nonhuman primate models of inhalation anthrax are regarded as relevant for the demonstration of the efficacy of therapeutic and prophylactic agents in treating or preventing anthrax infection. A single dose of ABthrax also fully protected rats against a lethal challenge with the anthrax toxins. Full results of these studies will be disclosed in upcoming scientific meetings and publications as appropriate. Currently, two options are available for the prevention or treatment of anthrax infections -- a vaccine and antibiotics. Both are essential to dealing with anthrax, but both have limitations. The anthrax vaccine takes several weeks following the first doses before immunity is initially established. The vaccine also requires multiple injections over a period of eighteen months, in addition to annual boosters, to maintain its protective effect. Antibiotics are effective in killing anthrax bacteria, but are not effective against the anthrax toxins once those toxins have been released into the blood. Antibiotics also may not be effective against antibiotic-resistant strains of anthrax. In ABthrax, Human Genome Sciences has discovered a third mechanism of defense against anthrax infections. In contrast to the anthrax vaccine, the protection afforded by a single dose of ABthrax would be immediate following the rapid achievement of appropriate blood levels of the antibody. In contrast to antibiotics, ABthrax acts against the lethal toxins produced by anthrax bacteria. It may also prevent and treat infections by antibiotic-resistant strains of anthrax. Most anthrax fatalities are caused by the irreversible effects of the anthrax toxins. Research has shown that protective antigen is a central component of the anthrax toxins that contribute to the progression of anthrax infection at the cellular level.3 After protective antigen and the anthrax toxins are produced by the bacteria, protective antigen binds to the anthrax toxin receptor on cell surfaces and forms a protein-receptor complex that makes it possible for the anthrax toxins to enter the cells. ABthrax blocks the binding of protective antigen to cell surfaces and prevents the anthrax toxins from entering and killing the cells. ABthrax was developed using technology that Human Genome Sciences has integrated into the Company as part of its collaboration with Cambridge Antibody Technology.4 David C. Stump, M.D., Senior Vice President, Drug Development, said, “We are pleased to be able to proceed with a clinical trial to evaluate the safety, tolerability, and pharmacology of ABthrax in healthy adults. Positive results from such a human study, along with our preclinical proof of efficacy data, would support the further development of ABthrax as a new means to prevent and treat anthrax infections. We believe that ABthrax has the potential to provide significant protection when given prophylactically, and may lessen the natural progression of anthrax infection and increase survival if given as a post-exposure treatment. ABthrax also may prevent and treat infections by antibiotic-resistant strains of anthrax.” Craig A. Rosen, Ph.D., President, Research and Development, said, “Research has shown that protective antigen is a rational target of the toxin components that contribute to the pathogenesis of anthrax infection. By inhibiting protective antigen, the anthrax toxins are inhibited. Multiple in vivo and in vitro preclinical studies demonstrate that ABthrax specifically recognizes and neutralizes protective antigen. A single dose of ABthrax increases survival significantly in both rabbit and nonhuman primate models of inhalational anthrax. In both studies, we noted the absence of bacteria in the blood of all treated animals that survived, suggesting a sporicidal and/or bactericidal effect.” William A. Haseltine, Ph.D., Chairman and Chief Executive Officer, said, “Based on our preclinical results to date, we believe that ABthrax has the potential to improve significantly the protection of individuals at a high-risk for exposure to anthrax, such as military personnel or civilian rescue teams in environments that may be infected. ABthrax may have the additional potential to improve survival when administered following exposure to anthrax. “The primary focus of Human Genome Sciences has not been the development of drugs to protect against attack by biological and chemical weapons. Nevertheless, we realized that our company had the technology and capability to develop an effective countermeasure against anthrax, one of the nation’s most immediate and serious bioterrorism threats. As a company headquartered just outside Washington, D.C., we witnessed first-hand in late 2001 the potentially devastating effects of the use of anthrax as a terrorist weapon. Thus, with our own resources, we developed a human monoclonal antibody drug that we believe has the potential to be given prior to or after exposure, and that could be used alone or in conjunction with the current vaccine and antibiotics. “We have shown, in multiple animal models, that ABthrax is effective against high doses of inhaled anthrax spores. We are able to manufacture this drug ourselves and now have received clearance to proceed with human safety trials. However, it is important to note that our ability to carry this project forward is ultimately dependent on the government’s willingness to commit to purchasing ABthrax. With proper funding, ABthrax could be available for emergency use as early as the end of 2004.” For more information about anthrax, please visit the Centers for Disease Control and Prevention (CDC) web site on bioterrorism and anthrax at http://www.bt.cdc.gov/agent/anthrax/index.asp. Health professionals interested in more information about trials involving HGSI products are encouraged to inquire via the Contact Us section of the Human Genome Sciences web site, www.hgsi.com/products/request.html, or by calling us at (301) 610-5790, extension 3550. Human Genome Sciences is a company with the mission to treat and cure disease by bringing new gene-based drugs to patients. HGS, Human Genome Sciences, and ABthrax are trademarks of Human Genome Sciences, Inc. This announcement contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. The forward-looking statements are based on Human Genome Sciences’ current intent, belief and expectations. These statements are not guarantees of future performance and are subject to certain risks and uncertainties that are difficult to predict. Actual results may differ materially from these forward-looking statements because of the Company’s unproven business model, its dependence on new technologies, the uncertainty and timing of clinical trials, the Company’s ability to develop and commercialize products, its dependence on collaborators for services and revenue, its substantial indebtedness and lease obligations, its changing requirements and costs associated with planned facilities, intense competition, the uncertainty of patent and intellectual property protection, the Company’s dependence on key management and key suppliers, the uncertainty of regulation of products, the impact of future alliances or transactions and other risks described in the Company’s filings with the Securities and Exchange Commission. Existing and prospective investors are cautioned not to place undue reliance on these forward-looking statements, which speak only as of today’s date. ABthrax is a new treatment that has not yet been tested on humans. The Company can provide no assurance that ABthrax will be effective in humans, or that any approved drug will result or be commercialized successfully. Human Genome Sciences undertakes no obligation to update or revise the information contained in this announcement whether as a result of new information, future events or circumstances or otherwise. # # # Footnotes: 1. (HGSI Press Release) Human Genome Sciences Develops New Means to Prevent and Treat Anthrax Infections. March 18, 2003. 2. Public Health Security And Bioterrorism Preparedness And Response Act Of 2002: Section 123. http://www.fda.gov/oc/bioterrorism/PL107-188.html. 3. Inglesby TV, O’Toole T, Henderson DA, et al. Anthrax as a Biological Weapon, 2002: Updated recommendations for Management. JAMA May, 2002. 287(17): 2236-2252.
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