PharmAthene Reports New Non-Clinical Data Demonstrating SparVax Anthrax Vaccine Can Provide Protection Against Lethal Anthrax Challenge

PharmAthene, Inc.

announced today that new non-clinical animal data from the Company's SparVax^® next-generation anthrax vaccine program were presented at the 53^rd Annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in Denver, Co. The data presented showed that immunization with SparVax^® provides dose-dependent protection against lethal anthrax infection. Dr. Sherry Crowe, Director, Immunology at PharmAthene, discussed the results in an oral presentation entitled, "Recombinant Protective Antigen Vaccine (SparVax^®) Provides Protection against Lethal Challenge with Bacillus anthracis in New Zealand White Rabbits." Summary of SparVax^® Findings Reported The need for newer anthrax vaccines based on modern vaccine technology, which offer the potential for improved safety, convenience and cost-effectiveness, is widely acknowledged.  SparVax^® is a next-generation anthrax vaccine based on recombinant protective antigen (rPA), the principal virulence factor of the organism, B. anthracis.  It is being developed for pre- and post-exposure protection against anthrax. Previous non-clinical animal studies have demonstrated that immunization with SparVax^® stimulates the production of anti-PA antibodies that provide protection against anthrax infection. The objective of the current study was to provide further confirmation of the immunogenicity and efficacy of SparVax^® (manufactured in the U.S.) and determine the optimal dose range for protection. In the current study, New Zealand White rabbits were administered escalating doses of SparVax^® ranging from 0.003 micrograms to 1.0 micrograms of rPA.  Control animals received either no immunization or were administered saline. Following immunization, the animals were challenged with B. anthracis spores (Ames strain). The results demonstrated that SparVax^® was effective in providing protection against lethal inhalation anthrax challenge and resulted in no adverse clinical observations. In the study, immunization with SparVax^® stimulated a dose-dependent antibody response, which correlated with survival.