Jul 12 2007
BioSante Pharmaceuticals, Inc. announced new positive results demonstrating that its calcium phosphate (CaP) nanoparticle-based vaccine adjuvant, BioVant, may serve as an effective vaccine adjuvant for the development of a dose sparing vaccine against H5N1 avian flu, widely known as bird flu.
The new results are based on a study using a hemagglutination inhibition assay (HAI), which showed the clear adjuvanting effect of BioVant. After a prime and one booster of BioVant-H5N1-combination- vaccine, the immune response in a rodent model was four-fold that of the H5N1 antigen alone. The study was done with 3 micrograms of H5N1 antigen in each vaccine dose. Earlier this year, the U.S. Food and Drug Administration approved an H5N1 vaccine that uses 90 micrograms of H5N1 antigen by itself given in each of two doses.
"We are working to create a vaccine using our BioVant that would be given at lower doses per injection yet still confer a higher level of immunity than the currently approved vaccine," said Stephen M. Simes, president and chief executive officer of BioSante. "These HAI study results confirm the BioVant antibody results previously reported and add to the data base for a potential BioSante improved BioVant adjuvanted bird flu vaccine."
"According to a paper published in the New England Journal of Medicine, the currently approved bird-flu vaccine without an adjuvant by a European drug company is effective only at high doses (90 micrograms per dose) and only 54 percent of subjects produced the desired immune response. We believe a BioVant-adjuvanted H5N1 vaccine may use less antigen per dose and protect a higher percentage of the population." Mr. Simes continued.
BioSante's preclinical study objective was to determine whether BioVant could enhance the body's natural immune response to the H5N1 viral antigen, the cause of bird flu. At the start of the trial, mice received either the H5N1 antigen alone or in a formulation with BioVant. A booster immunization was administered after two weeks. Results indicated that the administration of a BioVant-H5N1 formulation stimulated production of high titers of H5N1-specific antibodies, which were significantly higher than H5N1 alone. Anti-avian flu antibody levels continued to increase over the entire study period, suggesting good duration of immunity.
Avian flu refers to a large group of different influenza viruses that primarily affect birds. While the vast majority of these viruses do not affect humans, the H5N1 strain already has made the jump from birds to humans and in fact, has infected 310 people and killed 190 since the outbreak of the disease in 2003, and more than 250 million chickens have been killed to stop the spread of the virus. Farmers and poultry producers already have suffered losses in the billions of dollars. There is widespread concern that a strain of avian flu will mutate into a new form that is contagious among humans. Since there is currently no truly effective vaccine available to protect humans from H5N1 and humans do not have antibodies to fight this new virus strain, there is significant risk of a pandemic.
An adjuvant is a substance that, when added to a vaccine, enhances the vaccine's effectiveness by stimulating an immune system response. In multiple studies, BioVant has been shown to be safe and cause minimal dose-dependent inflammation at the injection site, and has been shown to both prevent the manifestation of allergic response, and, to effectively 'switch off' established Th2-T-cell- associated allergic disease.