The United States Food and Drug Administration (FDA) has granted orphan drug designation to Valortim (MDX- 1303) for the treatment of anthrax infection. Valortim is an investigational fully human antibody created using Medarex's UltiMAb Human Antibody Development System that targets the Bacillus anthracis protective antigen, Medarex, Inc. and PharmAthene, Inc., a privately held biotechnology company specializing in the development of biodefense therapeutics, announced here.

"Despite aggressive antibiotic therapy and supportive care, the anthrax attacks of 2001 resulted in a mortality rate of nearly 50%, illustrating the urgent need for more effective anthrax therapeutics," remarked David P. Wright, President and Chief Executive Officer of PharmAthene. "Our receipt of orphan drug designation for Valortim and, earlier this year, fast track designation, should facilitate a more streamlined development process through more frequent dialogue with the FDA," he added.

Wright continued, "We believe Valortim may be the superior choice for procurement in the Strategic National Stockpile under Project BioShield. Its mechanism of action appears to work under the same mechanism as the natural protective response to anthrax vaccine yet Valortim has the potential to provide immediate immunity compared to vaccines, which may take months to confer immunity. Animal studies have demonstrated efficacy in both pre- and post-exposure prophylaxis and treatment for anthrax infection, potentially enabling therapeutic intervention after the appearance of disease symptoms, when antibiotic therapy is progressively less effective."

Valortim (MDX-1303) is a fully human antibody designed to protect against inhalation anthrax, the most lethal form of illness in humans caused by the Bacillus anthracis bacterium. The investigational antibody is designed to target a protein component known as the anthrax protective antigen of the lethal toxin complex produced by the bacterium. The anthrax protective antigen is believed to initiate the onset of the illness by attaching to cells in the infected person, and then is believed to facilitate the entry of additional destructive toxins into the cells. Valortim is designed to target anthrax protective antigen and protect the cells from damage by the anthrax toxins.