ROCKVILLE, Md., Dec. 18 Human Genome Sciences,Inc. (Nasdaq: HGSI) today announced that the results of two animal studiesdemonstrated the life-saving potential of its human monoclonal antibody drugABthrax(TM) (raxibacumab). The results show that a single dose of ABthrax,administered without concomitant antibiotics, improved survival rates by up to64 percent when administered after animals were symptomatic for anthraxdisease as a result of inhalation exposure to massively lethal doses ofanthrax spores. These dramatic and statistically significant findingsdemonstrate a survival benefit in two animal species, which is the requirementfor establishing the efficacy of new drugs used to counter bioterrorism.
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"We believe that ABthrax offers a significant step forward in thetreatment of inhalational anthrax, and could play an important role instrengthening America's arsenal against bioterrorism," said H. Thomas Watkins,President and Chief Executive Officer, HGS.
ABthrax, which specifically targets anthrax toxins and is being developedunder contract with the Biomedical Advanced Research and Development Authority(BARDA), represents a new way to address the anthrax threat. While antibioticscan kill the Bacillis anthracis bacteria, they are not effective against thedeadly toxins that the bacteria produce -- the real culprits in anthrax-related deaths. ABthrax targets anthrax toxins after they are released intothe blood. In an inhalation anthrax attack, people may not know they areinfected with anthrax until the toxins already are circulating in their blood,and it may be too late for antibiotics alone to be effective.
"These results show that ABthrax was highly effective as a treatment foranthrax in both rabbits and monkeys, and acted quickly to provide asignificant survival benefit to animals showing clinical symptoms caused byexposure to massively lethal aerosolized doses of anthrax spores," said DavidC. Stump, M.D., Executive Vice President, Research and Development, HGS. "Thenew data are consistent with the results of previous studies in multipleanimal models, which demonstrated that a single dose of ABthrax givenprophylactically provided up to 100% protection against death."
HGS said that it has met all milestones to date under the Company'scontract with the U.S. Department of Health and Human Services (HHS), and ison track to deliver ABthrax to the Strategic National Stockpile beginning in2008.
"We have demonstrated the efficacy of ABthrax in multiple therapeutic andprophylactic animal models of inhalational anthrax," said James H. Davis,Ph.D., J.D., Executive Vice President and General Counsel, HGS. "We havedemonstrated that it was generally safe and well tolerated in two clinicaltrials to date in healthy adults. We have manufactured conformance lots ofABthrax and are currently producing ABthrax for delivery to the Stockpile. Wehave more work to do, but our interactions with HHS, FDA and CDC continue tobe positive, and the ABthrax program is progressing well."
In one of the animal studies, three groups of monkeys were exposed byinhalation to anthrax spores and treated with either ABthrax or placebo afterthey showed clinical signs of anthrax disease. After 28 days, the study foundthat:
A separate study that measured 14-day survival in rabbits alsodemonstrated a statistically significant survival benefit versus placebo. AllABthrax-treated animals that survived in both studies were rapidly cleared ofanthrax toxin and bacteria following intravenous administration of a singledose of ABthrax. In contrast, all placebo-treated animals remained bacteremicor toxemic and died.
HGS also reported today that it has completed the second safety study ofABthrax in human volunteers, bringing the total number of people who h