After Six Years, Botulism Antitoxin Prepares for FDA Animal Rule Review

| 11 January 2013

The US Food and Drug Administration (FDA), which recently cleared two drugs using a unique regulatory pathway aimed at facilitating the development and approval of medical countermeasures and dangerous pathogens, may be closing in on the approval of yet a third.

The Animal Rule Pathway

The pathway, known as the Animal Rule pathway, was born out of the events following the 9/11 terror attacks, when spores of anthrax were sent around the country using the postal system. Soon after, regulators developed the pathway in the hopes of lowering the barriers to entry for products intended to treat rare but dangerous diseases.

The pathway is structured in such a way as to provide manufacturers the ability to use well-validated animal studies to test the efficacy of drugs in lieu of humans, both of which need to be exposed to the pathogen in order to adequately test the product. Safety testing, however, is generally still conducted in healthy human adults.

Without that exemption, the theory went, FDA would never approve the investigational new drug applications to start clinical trials because the risks of testing a product by using human test subjects infected with a dangerous-and potentially lethal-pathogen are too ethically dubious.

The hope was that products would soon be made available to treat anthrax and a host of other dangerous diseases that government anti-terror and infectious disease experts said were a threat to the American public. With federal dollars flowing heavily toward homeland security efforts, companies began to invest in the idea.

But for all FDA's hopes, though, progress has been slow to come. Just two products-Johnson and Johnson's plague antibiotic, Levaquin (levofloxacin), and GlaxoSmithKline's anthrax-treating monoclonal antibody, raxibacumab-were approved in 2012, bringing the grant total to six products.

Botulism Antitoxin: The Third Approval?

Now FDA says a seventh product, Cangene's biologics licensing application (BLA) for botulism antitoxin heptavalent (A, B, C, D, E, F, G)-(Equine), is seeking approval under "FDA's authority to approve a product based on evidence of safety in humans and effectiveness from studies in animals when human efficacy studies are not ethical or feasible."

In other words, the Animal Rule.

Cangene, a Winnipeg, Canada-based company, has frequently worked with an obscure agency known as the Biomedical Advanced Research and Development Authority (BARDA), which works closely with companies to develop new treatments under the Animal Rule pathway and stockpile treatments for the US Strategic National Stockpile (SNS).

A statement from Cangene indicates that the US government has already purchased the product in large amounts-at least $200 million worth as of June 2011-as part of Project BioShield, an initiative of the US Department of Health and Human Services (DHHS). The product, however, appears to have never been approved by FDA, and the company's BLA comes more than six years after it first received a contract to make the supplies available.

At the time, DHHS said the product was necessary to stockpile due to the botulinum toxin's potential to "pose a threat to the US population" and the recommendation of the interagency Weapons of Mass Destruction Medical Countermeasures Subcommittee.

Another statement by the company indicates it is in the midst of developing its own anthrax treatment, Anthrax Immune Globulin Intravenous (AIGIV), and has until 2016 to get approval for the product from FDA.

FDA's meeting on the Animal Rule BLA will occur on 12 February 2013.


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Tags: Animal Rule

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