Avanir Pharmaceuticals Generates Antibody Effective at Neutralizing Key Anthrax Toxin

SAN DIEGO -- Avanir Pharmaceuticals announces that using its Xenerex technology it has generated a fully human antibody that successfully neutralizes the key toxin of the Class A biowarfare agent anthrax. This antibody candidate could potentially, either alone or in combination with other antibodies, provide immediate immunity to individuals who have been exposed to anthrax or who suspect they have been exposed.

"Currently there is a gap in treatment for individuals that could be or are exposed to anthrax spores," stated Gerald J. Yakatan, PhD, president and CEO of Avanir Pharmaceuticals. "Because of the long immunization timeframe of the vaccine currently available, there are groups of individuals for whom vaccination against anthrax is not possible or effective and for whom alternative therapies need to be developed. Our research is aimed at developing human antibodies that can neutralize the anthrax toxin after exposure has occurred, and we have achieved an important milestone in that effort."

The company's promising lead candidate has demonstrated both high affinity and the capability to neutralize the protective antigen (PA) anthrax toxin. Avanir is moving forward in its pre-clinical development plan with the aim of eventually providing an important component in the nation's comprehensive biodefense efforts.

The B. anthracis organism was one of the first biological warfare agents to be developed and continues to be a major threat in this regard. The anthrax exotoxin consists of three parts, the protective antigen (PA), the lethal factor (LF), and the edema factor (EF) toxins. The PA toxin has been the subject of most treatment efforts undertaken to date, including vaccines, because it is believed that neutralizing the PA toxin may prevent the LF and EF toxins from accessing and destroying human cells. Although vaccine strains have been developed, currently there are concerns regarding their efficacy and suitability for wide-spread use in the civilian population. The only FDA approved anthrax vaccine, BioThrax, requires six injections given over 18 months, with annual booster injections recommended thereafter.

Anthrax is one of the primary targets discussed in President Bush's proposed Project BioShield, a comprehensive effort to develop and make available modern, effective countermeasures against biological and other dangerous agents announced in the recent State of the Union address. Project BioShield, a joint activity of the new Department of Homeland Security and the Department of Health and Human Services, will make available almost $6 billion to purchase new countermeasures for smallpox, anthrax, and botulinum in the next 10 years.

Avanir has developed a proprietary platform technology that is capable of generating fully human antibodies to target antigens through the engraftment of human immune system cells into immunodeficient mice. By screening and selecting cells from donors that already produce protective antibodies, the likelihood of a successful outcome is greatly increased.

The Xenerex technology is ideally suited to generating fully human antibodies to infectious diseases in general and biowarfare agents in particular. Scientists identify the specific human protective antibody- producing lymphocytes and create a recombinant antibody cell line. The monoclonal antibody product harvested from these lines provide the means of treating the disease.

A government grant from CCAT was awarded in June 2002 to fund the initial development of the anthrax treatment. The Center for Commercialization of Advanced Technology (CCAT) is a joint project administered by the San Diego State University Foundation and the Department of Defense with the mission of providing initial funding for promising technologies in biodefense.

Avanir intends to use its Xenerex technology to generate human antibodies to the remaining two toxins of anthrax as well as the toxins produced by C. Botulinum. In addition to the Company's biodefense effort, a commercial program is underway to generate useful fully human antibody product candidates to selected viral and bacterial organisms where unmet medical needs exist.

Source: Avanir Pharmaceuticals