Human Genome Sciences, Inc. (Nasdaq: HGSI) announced today that the U.S. Food and Drug Administration (FDA) has acknowledged receipt of the resubmission of the Biologics License Application (BLA) for raxibacumab, a treatment for inhalational anthrax, and has established December 15, 2012 as the Prescription Drug User Fee Act (PDUFA) action date. The FDA has deemed the resubmission a complete, class 2 response to its November 14, 2009 complete response letter, which requested further analyses of existing data as well as additional information. The BLA resubmission contains additional evaluation of histopathology of survivors and non-survivors in animal studies, evaluation of potential added benefit of using raxibacumab with antibiotics versus antibiotics alone, and additional validation to confirm previous data. “We look forward to working with the FDA to continue to move raxibacumab through the regulatory review process over the next several months,” stated Sally D. Bolmer, Ph.D., R.A.C., Senior Vice President, Development and Regulatory Affairs, Human Genome Sciences. The July 9, 2009 edition of The New England Journal of Medicine published the results of two pivotal randomized placebo-controlled studies conducted in rabbits and monkeys to evaluate the efficacy of raxibacumab, as well as the results of human safety studies, which supported the use of raxibacumab in the event of life-threatening inhalation anthrax disease. Raxibacumab is a human monoclonal antibody that represents a novel 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. Raxibacumab targets anthrax toxins after they are released by bacteria into blood and tissues. Raxibacumab 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). In 2009, HGS delivered the first 20,000 doses of raxibacumab to the U.S. Strategic National Stockpile, and, in July 2009, the U.S. Government exercised its option to purchase 45,000 additional doses for the Stockpile for emergency use in treating inhalation anthrax, with delivery to be completed over a three-year period.