ANNAPOLIS, Md., Dec. 6, 2011 /PRNewswire/ -- PharmAthene, Inc. (NYSE Amex: PIP) today announced that results from a Phase I clinical study of Valortim ® were published in the December issue of Clinical and Vaccine Immunology. The American Society for Microbiology peer-reviewed journal describes clinical data supporting the potential use of Valortim ®, a fully human monoclonal antibody, as both a post-exposure prophylaxis and therapeutic treatment for anthrax infection. "There is a strong need for additional therapeutic options for inhalational anthrax disease as current therapies, specifically antibiotics and aggressive supportive care, are not optimally effective in individuals with active, symptomatic anthrax infection. Anti-toxin therapies like Valortim ® could potentially provide important protection in the event of a bioterrorism attack with anthrax," remarked Dr. Thomas Fuerst, Executive Vice President and Chief Scientific Officer. "Our Phase I results demonstrate that a single dose of Valortim ® can provide levels of antibodies in humans that correspond to protective levels in animal models and is well tolerated. Based on the accumulating human safety and animal efficacy data for Valortim ®, we believe that it could represent an important addition to the nation's anthrax armamentarium." Preclinical studies suggest that Valortim ® has the potential to provide significant protection against anthrax infection when administered prophylactically (prior to the emergence of symptoms of anthrax infection) and also may increase survival when administered therapeutically (once symptoms become evident). In these studies, Valortim ® has been shown to protect both rabbits and monkeys against the lethal effects of anthrax infection when administered at the time of exposure, at doses as low as 1.0 mg/kg. When administered to rabbits after the development of symptoms, Valortim ® also improved survival as late as 48 hours post-exposure as compared to controls. The Phase I clinical study was conducted to assess the safety and tolerability of Valortim ®. Forty-six healthy volunteers received either a single intravenous (IV) dose of Valortim ® ranging from 0.3 to 20.0 mg/kg (10 subjects in cohorts receiving 1.0, 3.0 or 10.0 mg/kg and 3 subjects in cohorts receiving 0.3 and 20 mg/kg) or a single 100 mg intramuscular (IM) dose of Valortim ® (10 subjects). The Phase I data showed that Valortim ® was generally safe and well-tolerated and non-immunogenic when administered as single 0.3 mg/kg to 20 mg/kg IV infusions or as a single IM dose injection at 100 mg. No drug-related Grade 2-4 or serious adverse events were reported. Grade 1 adverse events were reported in 16 of the volunteers overall, with the most common being pain/burning at the injection site for those being dosed intramuscularly (6 subjects). There were also a few mild headaches (3 subjects overall). Initial analyses of serum pharmacokinetics revealed increasing peak concentrations and overall duration of exposure to antibody with increasing dose, and a half-life of approximately 26 days for IV administration, and approximately 32 days for IM dosing. In the cohorts dosed with 1.0 mg/kg IV or 100 mg IM, individual subjects were tested for the level of toxin neutralizing activity present in their serum 71 days after dosing. The level of activity was comparable to the level of toxin neutralizing activity seen in pooled human sera provided by the CDC; these reference sera were generated from anthrax toxin immunized individuals, and provide a standard for defining a protective vaccine response. "We have continued to make solid progress in our Valortim ® program. In addition to these recently published Phase I data, we have completed the in-life portion of a second Phase I clinical study of Valortim ® and expect to report final study results later this year. Anti-toxins such as Valortim ® are an important part of our nation's biodefense arsenal," continued Dr. Fuerst. "The accumulating data suggest that Valortim ® is differentiated from other anthrax anti-toxins and possesses important characteristics that may make it a strong choice for procurement in the Strategic National Stockpile, including demonstrated efficacy in animal models as both a prophylactic and therapeutic for inhalational anthrax, efficacy at low doses, and a mechanism of action with unique properties. We look forward to continuing to work collaboratively with the U.S. Government to develop innovative new biodefense countermeasures like Valortim ® to protect our nation's citizens both at home and on the battlefield."