Immunovaccine Reports Positive Results from Two Anthrax Studies

Immunovaccine Inc. a clinical stage vaccine company, has announced positive results from anthrax challenge studies in rabbits and non-human primates using its DepoVax™ delivery system. The studies showed that all animals administered a vaccine containing recombinant protective antigen (PA) formulated in DepoVax were protected against a lethal anthrax challenge.

Importantly, a single dose of DepoVax containing five micrograms of recombinant PA protected rabbits exposed to a lethal anthrax dose. Antibody titers plateaued in rabbits within 28 days highlighting the DepoVax platform’s potential to enable a single-dose, rapid response anthrax vaccine. These studies, conducted under the National Institute of Allergy and Infectious Diseases’ (NIAID’s) preclinical services program, were intended to evaluate Immunovaccine’s DepoVax adjuvanting technology and advance the development of next generation bio-defense vaccines.

“These positive study results demonstrate the continued advancement of our promising bio-defense vaccine development program and highlight the versatile nature of our DepoVax platform beyond our lead clinical stage cancer vaccines,” stated Dr. Marc Mansour, chief operating officer of Immunovaccine. “This range of activity and development milestones underscores the potential of the DepoVax technology to enable next generation vaccines to address a variety of healthcare’s most pressing needs.”

Earlier investigation of Immunovaccine’s DepoVax-formulated vaccines conducted under the NIAID’s preclinical services program had revealed their ability to produce significant toxin neutralizing antibodies. These follow-up studies examined whether a single vaccination in rabbits or two vaccinations in both rabbits and non-human primates could provide sufficient immunogenicity and protection from anthrax.

In rabbits, NIAID-funded contractors demonstrated that a single vaccination protected against an aerosol anthrax challenge. In non-human primates, two doses containing recombinant PA formulated in DepoVax triggered sustained toxin neutralizing antibodies sufficient to protect them from a lethal anthrax challenge. A single dose response was not evaluated in non-human primates.

The rabbit studies also showed that the DepoVax-formulated vaccines began producing detectable and potentially protective toxin neutralizing antibodies in as little as 14 days with maximum protective antibody levels achieved within 28 days following a single vaccination. The titers were sustained for at least 70 days at which time the lethal anthrax challenge was performed. Neutralizing antibodies rose further in animals receiving a second dose of the DepoVax recombinant PA vaccine.

Preliminary data suggest that the DepoVax platform may generate a stronger immune response than BioThrax®, the only FDA-licensed vaccine available for pre-exposure protection against anthrax infection.

“We are greatly encouraged that the results from these challenge studies provide evidence that the DepoVax platform has the potential to make a single dose rapid response anthrax vaccine a reality,” said Dr. Mansour. “There is a significant need both in the U.S. and globally for a single dose anthrax vaccine that can provide strong protection in the shortest period of time in the event of a bioterrorism incident.”

The company plans further studies on the use of DepoVax-based recombinant PA vaccines.