PharmAthene, Inc. Presents New SparVax® Anthrax Vaccine Data At The FDA Medical Countermeasures Initiative Symposium

ANNAPOLIS, Md., June 4, 2014 /PRNewswire/ -- PharmAthene, Inc. (NYSE MKT: PIP) announced today that new data from its SparVax^® anthrax vaccine program were recently presented at the 2014 U.S. Food and Drug Administration (FDA) Medical Countermeasures Initiative (MCMi) Regulatory Science Symposium in Silver Spring, MD.

In a presentation entitled, "Recombinant Protective Antigen Vaccine (SparVax^®) Provides Protection Equivalent to BioThrax^® Against Lethal Challenge with Bacillus anthracis in New Zealand White Rabbits," Dr. Sherry Crowe, Director, Immunology for PharmAthene, presented survival and toxin neutralization assay (TNA) results from a non-clinical anthrax aerosol challenge model.

In this study, three groups of twenty New Zealand White (NZW) rabbits were vaccinated with SparVax^® via intramuscular injection, on study days 0 and 28 at doses of 3, 9, or 27 micrograms. In addition, twenty animals were vaccinated with BioThrax^®, the currently-licensed anthrax vaccine. On the 70^th day of the study, the NZW rabbits were challenged with a lethal dose of aerosolized anthrax spores.

The results of the study demonstrated 100% survival (i.e. equivalent protection) of SparVax^® compared to BioThrax^®. In addition, the preliminary TNA data showed that the antibody titers for SparVax^® in this study were up to 2-fold higher than BioThrax^®, demonstrating that SparVax® is at least equivalent to BioThrax^® as measured by either survival or TNA using the benchmark NZW rabbit model.

Eric Richman, President and Chief Executive Officer, remarked, "These latest data provide additional supportive evidence of the potential efficacy of SparVax^® as a novel next-generation recombinant protective antigen (rPA)-based anthrax vaccine. One of the requirements for licensure of rPA vaccines is equivalency relative to the current vaccine, so we are encouraged by these results. We are also especially intrigued by the TNA data, which show elevated antibody titers (up to 2-fold higher) for SparVax^® as compared to BioThrax^®, suggesting the potential for a more potent immune response following vaccination with SparVax^®."

In a second poster presentation entitled "Imaging Capillary Electrophoresis Discriminates Slow from Fast Asparagine Deamidation that may Predict Potency for Recombinant Protective Antigen Anthrax Vaccines," Dr. Bradford Powell, Director, Analytical Sciences, presented new analytical data for SparVax^® evaluating the structural characteristics of rPA relative to biological activity. The ongoing expansion of this body of analytical work by Dr. Powell's team will assist PharmAthene in constructing a reliable stability model that will be useful in predicting the potential shelf life of the rPA anthrax vaccine.

PharmAthene's rPA anthrax vaccine program has been funded in whole or in part with federal funds from the National Institute of Allergy and Infectious Disease, National Institutes of Health and the Biomedical Advanced Research and Development Authority (BARDA).

About PharmAthene

PharmAthene is a biodefense company engaged in the development and commercialization of next generation medical countermeasures against biological and chemical threats. PharmAthene's current biodefense portfolio includes the following product candidates:

• SparVax^® - a next generation recombinant protective antigen (rPA) anthrax vaccine
• rBChE bioscavenger - a medical countermeasure for nerve agent poisoning by organophosphorous compounds, including nerve gases and pesticides
• Valortim^® - a fully human monoclonal antibody for the prevention and treatment of anthrax infection

In addition, in May 2013, the Delaware Supreme Court issued its ruling on the appeal in our litigation with SIGA Technologies, affirming the Delaware Court of Chancery's finding that SIGA was liable for breach of contract, reversing its finding of promissory estoppel, and remanding the case back to the Delaware Court of Chancery to reconsider the appropriate remedy and award of attorney's fees and expert witness costs in light of the Delaware Supreme Court's opinion. For more information about PharmAthene, please visit www.PharmAthene.com.

Forward-Looking Statement Disclaimer

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 preceded by, followed by, or that include the words: "will"; "potential"; "believe"; "anticipate"; "look forward"; "intend"; "plan"; "expect"; "estimate"; "could"; "may"; "should"; or similar statements are forward-looking statements. Such statements include, but are not limited to those referring to the outcome of the SIGA litigation and our ability to deploy our resources. PharmAthene disclaims any intent or obligation to update these forward-looking statements. Risks and uncertainties include, among others, risks associated with the reliability of the results of the studies relating to human safety and possible adverse effects resulting from the Company's product candidates; our ability to demonstrate effectiveness of our technology and improve our 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, such as BARDA's recent decision to de-scope the current SparVax^® anthrax vaccine contract through a partial termination for convenience; awards of government contracts to our competitors; unforeseen safety issues; 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 annual reports on Form 10-K and quarterly reports on Form 10-Q under the caption "Risk Factors" and in its other reports filed with the U.S. Securities and Exchange Commission. In particular, there is significant uncertainty regarding the level and timing of sales of Arestvyr and whether and when it will be approved by the FDA and corresponding health agencies around the world. PharmAthene cannot predict with certainty if or when SIGA will begin recognizing profit on the sale thereof and there can be no assurance that any profits received by SIGA will be significant. In its May 2013 decision, the Delaware Supreme Court reversed the remedy ordered by the Delaware Court of Chancery and remanded the issue of a remedy back to the trial court for reconsideration in light of the Delaware Supreme Court's opinion. As a result, there can be no assurance that the Delaware Chancery Court will issue a remedy that provides PharmAthene with a financial interest in Arestvyr and related products or any remedy. In addition, significant additional research work, non-clinical animal studies, clinical trials, and manufacturing development work remains to be done with respect to PharmAthene's product candidates. At this point, future government funding to support development of Valortim^®, rBChE, and SparVax^® is unlikely and remains uncertain. It is also uncertain whether any of our product candidates 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 its website under the investor relations tab at www.pharmathene.com.

SOURCE PharmAthene, Inc.