Human Genome Sciences Begins Delivery of First-in-Class Anthrax Treatment to U.S. Strategic National Stockpile

ROCKVILLE, MD--(Marketwire - February 2, 2009) - Human Genome Sciences, Inc. (NASDAQ: HGSI) today announced that it has begun delivery of 20,000 doses of its human monoclonal antibody drug ABthrax™ (raxibacumab) to the U.S. Strategic National Stockpile for use in the treatment of inhalation anthrax.

ABthrax is a first-in-class treatment for anthrax, and the first procurement under Project BioShield of a product discovered and developed after the September 11, 2001 terrorist attacks. It specifically targets the deadly toxins released within the human body by Bacillus anthracis that are the real culprits in anthrax-related deaths. ABthrax is being developed under a contract entered into in 2006 with the Biomedical Advanced Research and Development Authority (BARDA) of the Office of the Assistant Secretary for Preparedness and Response (ASPR), U.S. Department of Health and Human Services (HHS).

"We believe ABthrax offers a significant step forward in the treatment of inhalation anthrax and could play an important role in strengthening America's arsenal against bioterrorism," said H. Thomas Watkins, President and Chief Executive Officer, HGS. "From a business perspective, this announcement is strategically important for HGS, because it marks our Company's first product sales. We expect to receive $150 million in revenue soon after completion of our delivery to the Strategic National Stockpile. We are pleased with the progress of our partnership with the U.S. Government, which has resulted in this important milestone, and we are hopeful that fulfillment of this initial order will result in a long-term relationship involving additional deliveries of ABthrax to the Stockpile."

ABthrax represents a new way to address the anthrax threat. While antibiotics can kill the anthrax bacteria, they are not effective against the deadly toxins that the bacteria produce. ABthrax targets anthrax toxins after they are released by the bacteria into the blood and tissues. In an inhalation anthrax attack, people may not know they are infected with anthrax until the toxins already are circulating in their blood, and it may be too late for antibiotics alone to be effective.

"We are delighted to have fulfilled this important milestone under our contract with the U.S. Government and we hope we are making a significant contribution to our nation's security," said James H. Davis, Ph.D., J.D., Executive Vice President and General Counsel, HGS, and leader of the Company's ABthrax program with the U.S. Government. "We are particularly pleased with the relationship we have had with BARDA in the development of ABthrax, and we look forward to continuing to work together."

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