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."

About PharmAthene, Inc.

PharmAthene was formed to meet the critical needs of the United States and its allies by developing and commercializing medical countermeasures against biological and chemical weapons. PharmAthene's lead product development programs include:

SparVax™ - a second generation recombinant protective antigen (rPA) anthrax vaccine
Valortim^® - a fully human monoclonal antibody for the prevention and treatment of anthrax infection
Recombinant BChE- a novel bioscavenger for the prevention and treatment of morbidity and mortality associated with exposure to chemical nerve agents

In addition, pursuant to an opinion issued September 22, 2011 from the Delaware Court of Chancery, PharmAthene is entitled to 50% of the net profits over 10 years from all sales of SIGA Technologies' ST-246, a novel smallpox antiviral agent being developed by SIGA for the treatment and prevention of morbidity and mortality associated with exposure to the causative agent of smallpox, and related products, once SIGA receives the first $40 million in net profits from sales of ST-246. For more information about PharmAthene, please visit [ www.PharmAthene.com ].

Statement on Cautionary Factors

Except for the historical information presented herein, matters discussed may constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 that are subject to certain risks and uncertainties that could cause actual results to differ materially from any future results, performance or achievements expressed or implied by such statements. Statements that are not historical facts, including statements proceeded by, followed by, or that include the words "potential"; "believe"; "anticipate"; "intend"; "plan"; "expect"; "estimate"; "could"; "may"; "should"; "will"; "project"; "potential"; or similar statements are forward-looking statements. PharmAthene disclaims any intent or obligation to update these forward-looking statements other than as required by law. Risks and uncertainties include risk associated with the reliability of the results of the studies relating to human safety and possible adverse effects resulting from the administration of the Company's product candidates, unexpected funding delays and/or reductions or elimination of U.S. government funding for one or more of the Company's development programs, the award of government contracts to our competitors, unforeseen safety issues, challenges related to the development, scale-up, technology transfer, and/or process validation of manufacturing processes for our product candidates, unexpected determinations that these product candidates prove not to be effective and/or capable of being marketed as products, as well as risks detailed from time to time in PharmAthene's Forms 10-K and 10-Q under the caption "Risk Factors" and in its other reports filed with the U.S. Securities and Exchange Commission (the "SEC"). In particular, significant additional non-clinical animal studies, human clinical trials, and manufacturing development work remain to be completed for Valortim^®. At this point there can be no assurance that Valortim^® will be shown to be safe and effective and approved by regulatory authorities for use in humans. Copies of PharmAthene's public disclosure filings are available from its investor relations department and our website under the investor relations tab at [ www.PharmAthene.com ].

SOURCE PharmAthene, Inc.

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Pharmathene Announces Publication of Phase I Study Results for Anthrax Anti-toxin Valortim

Pharmathene Announces Publication of Phase I Study Results for Anthrax Anti-toxin Valortim

Results Support Potential Utility of Valortim for Prevention and Treatment of Anthrax Infection