FDA Approves First Anthrax Antitoxin

On Dec. 14, 2012, FDA approved raxibacumab injection to treat inhalational anthrax, a form of the infectious disease caused by breathing in the spores of the bacterium Bacillus anthracis. Raxibacumab is also approved to prevent inhalational anthrax when alternative therapies are not available or not appropriate. Raxibacumab is a monoclonal antibody that neutralizes toxins produced by B. anthracis.

Raxibacumab was developed by Human Genome Sciences (HGS) in conjunction with the Biomedical Advanced Research and Development Authority (BARDA) of the Office of the Assistant Secretary for Preparedness and Response (ASPR), US Department of Health and Human Services (HHS). HGS was acquired by GlaxoSmithKline in July, 2012, making raxibacumab part of GSK’s portfolio.

Raxibacumab is the first monoclonal antibody approved under FDA’s Animal Efficacy Rule, which allows efficacy findings from adequate and well-controlled animal studies to support FDA approval when it is not feasible or ethical to conduct trials in humans. In this case, because inhalational anthrax is a rare and lethal disease, it is not possible to conduct adequate efficacy trials in humans. 

In addition, the drug is the first to be developed under Project Bioshield to receive FDA approval, according to a press release from HHS.  The Project Bioshield Act was signed in 2004 and provides funding to support and expedite the development and procurement of medical countermeasures against chemical, biological, radiological, and nuclear threats. According to GSK’s press release, the US Government is currently the sole recipient of raxibacumab supplies.