By Michael S. Rosenwald
Washington Post Staff Writer
Wednesday, December 19, 2007

Human Genome Sciences said yesterday that ABthrax, its experimental treatment for anthrax infection, dramatically increased survival in animals exposed to lethal doses of anthrax spores.

The results mark the last significant scientific hurdle that the Rockville company needs to clear to complete the federal government's $165 million order of 20,000 doses of the drug.

Products such as ABthrax are part of a three-pronged defense against anthrax attacks. Vaccines can prevent infection, but several weeks and multiple doses are typically required to build up immunity. Antibiotics can kill the anthrax bacteria but aren't effective against toxins once they are released in the body by an anthrax infection. ABthrax prevents those toxins from entering and killing cells.

In a study with monkeys, 64 percent of the animals receiving a single dose of ABthrax survived after exposure to lethal doses of anthrax spores. None of the monkeys given a placebo survived. The drug has been successfully tested for safety in humans but not for efficacy because that would require exposing people to a deadly bioterrorism agent.

"We believe that ABthrax offers a significant step forward in the treatment of inhalational anthrax, and could play an important role in strengthening America's arsenal against bioterrorism," H. Thomas Watkins, the company's chief executive, said in a statement.

After completing a final safety study, Human Genome Sciences will be on track to begin delivering the product to the government's strategic national stockpile late next year. A successful completion of the contract would mark the company's first product sales in its 15 years of existence.

The company is also developing treatments for lupus, rheumatoid arthritis, hepatitis and cancer.

Shares of Human Genome Sciences closed yesterday at $10.98, up 44 cents.