PharmAthene Presents Phase I Clinical Trial Results and New Therapeutic Animal Model Data for Protexia(R)

December 7, 2009

ANNAPOLIS, Md., Dec. 7 /PRNewswire-FirstCall/ — PharmAthene, Inc. (NYSE Amex: PIP), a biodefense company developing medical countermeasures against biological and chemical threats, today announced Phase I clinical trial results for Protexia®, a pegylated recombinant version of human butyrylcholinesterase (rBChE), which has been shown to be effective in animal models in preventing toxicity from exposure to chemical nerve agents. The results were presented in an oral presentation on Friday, December 4, 2009, at the Health and Human Services Public Health Emergency Medical Countermeasures Enterprise (PHEMCE) Stakeholders Workshop 2009 / BARDA Industry Day, in Washington, D.C.

“We are delighted to have the opportunity to present these positive data for Protexia® (peg-rBChE) at the PHEMCE conference,” commented David P. Wright, President and Chief Executive Officer. “These initial safety data in humans, coupled with available efficacy data in animals, suggest the potential for Protexia® as a valuable medical countermeasure for nerve agent toxicity. Preclinical studies suggest that in contrast to currently available treatments, Protexia® is the first medical countermeasure that can provide protection against both the physiological and neurological toxicities associated with nerve agent poisoning.”

“We are very grateful for the strong support PharmAthene has received from the Chemical Biological Medical Systems (CBMS) group within the Department of Defense (DoD), which has responsibility for overseeing all of the development activities for Protexia® under our advanced development and procurement contract with DoD,” continued Mr. Wright. “We continue to enjoy a very productive collaboration with both CBMS and the Department of Health and Human Services, as these agencies have worked closely together to ensure the advancement of novel medical countermeasures for our nation’s military personnel and citizens.”

The Phase I clinical study was a randomized, placebo-controlled, third-party double-blind, dose-escalating study conducted to assess the safety and tolerability of Protexia® administered intramuscularly at one or two time points in healthy human volunteers. Under the study protocol, either Protexia® or a saline placebo was administered in escalating doses to six groups of volunteers. A total of 33 subjects participated in the study; 22 of these subjects were treated with Protexia and 11 were treated with saline placebo. Five of the six dose groups (15 volunteers) received a single intramuscular (IM) dose of Protexia ranging from 50 to 750 mg. Subjects in the 250mg dose cohort (7 volunteers) received a second dose of Protexia® 72 days following the first dose.

The Phase I data showed that Protexia® was safe and well-tolerated. No serious adverse events were reported. The most common adverse events reported in the subjects receiving Protexia were injection site reactions, occurring in 19 of 22 volunteers.

As Protexia® was well-tolerated in the study, with no significant safety issues and no evidence of immunogenicity, these data suggest that Protexia® may be a promising new approach to the prophylaxis and treatment of nerve agent toxicity.

In addition, preclinical studies of Protexia® in animals have suggested that it has the potential to provide significant protection against chemical nerve agent poisoning when administered prophylactically (prior to exposure to nerve agent) and also may increase survival when administered therapeutically (following nerve agent exposure).

PharmAthene has been collaborating with The Defense Science and Technology Laboratory (Dstl) on preclinical studies to investigate the therapeutic efficacy of Protexia®. New data from these studies were also presented at the PHEMCE conference. In a collaborative poster with Dstl entitled, “Post-Poisoning Treatment with Recombinant Butyrylcholinesterase Reduces VX Blood Concentration and Prevents VX-Induced Mortality,” investigators conducted research to determine the utility of rBChE as a post-nerve agent poisoning medical countermeasure in two guinea pig models.

Each of the models provided different assessments of exposure to organophosphorus nerve agent (VX) on the skin. In the first model, male guinea pigs were implanted with dermal and blood microdialysis probes to monitor nerve agent concentration in these tissues following exposure to VX. In a separate model, telemetry transponders were surgically implanted in animals to monitor the effects of exposure to VX on physiological parameters. VX was applied to the dorsal skin of the guinea pigs and rBChE or vehicle control was administered 30 or 120 minutes later.

Animals treated with rBChE 30 minutes post VX exposure had lower blood concentrations of VX than vehicle treated control animals. Additionally, treatment with rBChE 2 hours post VX exposure mitigated the physiological changes observed in vehicle treated animals, in addition to preventing lethality.

“The majority of our research to date for Protexia® (rBChE) has focused on studying its efficacy as a pre-exposure prophylactic. These results provide further encouraging evidence for the utility of post-poisoning treatment with rBChE. We plan to undertake further work to build upon these findings and define the window of therapeutic efficacy provided by treatment with rBChE,” continued Mr. Wright.

PharmAthene is developing Protexia® in collaboration with the U.S. Department of Defense (CBMS) as a broad spectrum prophylaxis for the U.S. military.

About Protexia®

Protexia® is a recombinant version of human butyrylcholinesterase (BChE), a naturally occurring protein found in minute quantities in blood (2 mg/liter). BChE functions as a natural bioscavenger, like a sponge, to absorb and degrade organophosphorus poisons (e.g. nerve agents) before they cause neurological damage. Protexia® is being developed as a pre- and post-exposure therapy for casualties on the battlefield or civilian victims of nerve agent attacks. Nerve agents belong to a class of compounds known as organophosphorus (OP) agents. OP nerve agents, such as sarin gas, soman, tabun or VX, enter the blood stream via inhalation or absorption through the skin. The nerve agents travel in the circulatory system to the brain and muscles causing the nerves to become over-stimulated which leads to massive convulsions and death in severe cases.

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(TM) — a second generation recombinant protective antigen (rPA) anthrax vaccine
  • Third generation rPA anthrax vaccine
  • Valortim® — a fully human monoclonal antibody for the prevention and treatment of anthrax infection
  • Protexia® — a novel bioscavenger for the prevention and treatment of morbidity and mortality associated with exposure to chemical nerve agents
  • RypVax(TM) — a recombinant dual antigen vaccine for plague

For more information about PharmAthene, please visit http://www.PharmAthene.com.

About CBMS

The Chemical Biological Medical Systems (CBMS) Joint Project Management Office rapidly provides the Warfighter with safe, robust, and affordable medical countermeasures against a broad spectrum of Chemical, Biological, Radiological, and Nuclear (CBRN) threats. Established in 2002, CBMS is a critical component in the Department of Defense’s (DoD) comprehensive national strategy to counter the threat of CBRN weapons of mass destruction. The CBMS is comprised of two subordinate offices: the Joint Vaccine Acquisition Program and the Medical Identification and Treatment Systems Product Management Offices. Together, these product offices use DoD and commercial best practices to combine Food and Drug Administration regulations with DoD acquisition policies to deliver materiel solutions to our Warfighters, the nation, and the world.

About Dstl

The Defence Science and Technology Laboratory (Dstl) is a centre of scientific excellence for the UK Ministry of Defence (MOD). Its 3,500 strong workforce includes some of the United Kingdom’s most talented and creative scientists with a mission to ensure that the UK Armed Forces and Government are supported in-house by the very best impartial scientific and technological advice. Dstl’s position at the heart of the MOD means that its advice is trusted by governments, academia, industry and international partners. It offers timely and accurate advice at all levels of military planning and operations, both overseas and on the home front. For more information please visit http://www.dstl.gov.uk .

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 preceded by, followed by, or that include the words “potential”; “believe”; “anticipate”; “intend”; “plan”; “expect”; “estimate”; “could”; “may”; “should”; or similar statements are forward-looking statements. PharmAthene disclaims, however, any intent or obligation to update these forward-looking statements. 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, 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 Form 10-K 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 research work, non-clinical animal studies, human clinical trials, and manufacturing development work remain to be done with respect to Protexia®. At this point there can be no assurance that this product candidate 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 http://www.pharmathene.com.

SOURCE PharmAthene, Inc.

Source: newswire

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