PharmAthene and Medarex Announce Additional $0.8 Million U.S. Government Appropriation for Continued Development of Anthrax Ther

Nov. 6, 2007

ANNAPOLIS, Md . and PRINCETON, N.J., Nov. 6 /PRNewswire-FirstCall/ -- PharmAthene, Inc. (Amex: PIP), a biodefense company developing medical countermeasures against biological and chemical threats, and Medarex, Inc. (Nasdaq: MEDX), a leading monoclonal antibody company, today announced that the FY 2008 Department of Defense (DoD) appropriations bill includes $0.8 million payable to PharmAthene on a cost reimbursement basis to support ongoing development of Valortim(TM), a fully human monoclonal antibody generated by Medarex's UltiMAb(R) technology that is being co-developed by the two companies. This is the third consecutive year in which PharmAthene has received appropriations funding for Valortim.

"The latest DoD appropriations funding will be used to support further study of Valortim in a promising new animal model of anthrax infection," commented Matthew G. Meldorf, M.D., Senior Program Director for Valortim at PharmAthene. The new model, which is being developed at the United States Army Medical Research Institute of Infectious Diseases (USAMRIID), seeks to improve on existing therapeutic models for anthrax by closely monitoring the disease process to establish the presence of anthrax bacteremia and to determine the optimal window for therapeutic intervention.

"It is currently very difficult to evaluate the therapeutic effect of new treatments because the mortality rate is very high and the time-course from anthrax exposure to death is quite rapid in existing anthrax models," said Dr. Meldorf . "The newly-developed USAMRIID model uses a rapidly detectable surrogate marker for the development of symptomatic anthrax disease. This will enable us to more accurately determine the therapeutic efficacy of Valortim in animals who have active disease defined in this way."

"Six years after the anthrax attacks of 2001, we believe that the development of effective therapies to prevent and treat anthrax infection is still a critical national security priority," said David P. Wright, President and Chief Executive Officer of PharmAthene. "Based on the promising preclinical and clinical data generated to date, we strongly believe that Valortim(TM) may be an appropriate choice for procurement in the Strategic National Stockpile under Project BioShield."

"We are pleased with the ongoing success of our colleagues at PharmAthene in securing external funding to support the advanced development of Valortim and believe that the new animal model under development at USAMRIID will help assess the therapeutic potency of this antibody," said Israel Lowy , M.D., Ph.D., Senior Director of Infectious Disease for Medarex. "Through our research we have identified important characteristics of Valortim, such as its mechanism of action, pharmacokinetics, animal efficacy, and favorable human safety data. We believe that these attributes will play a key role in the further development of Valortim and potential government procurement."

About Valortim

Valortim (MDX-1303) is a fully human antibody designed to protect against anthrax infection, including inhalation anthrax, the most lethal form of illness in humans caused by the Bacillus anthracis bacterium. The investigational antibody is designed to target a protein component known as the anthrax protective antigen (PA) of the lethal toxin complex produced by the bacterium. The anthrax protective antigen is believed to initiate the onset of the illness by attaching to cells in the infected person, and then is believed to facilitate the entry of additional destructive toxins into the cells. Valortim is designed to target anthrax protective antigen and protect the cells from damage by the anthrax toxins.

Valortim has been administered intravenously and intramuscularly to 46 healthy human volunteers in a completed phase I study, was well tolerated at doses as high as 20 mg/kg (IV), and was not immunogenic. The Phase I data showed that Valortim was safe and well-tolerated. 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). Pharmacokinetic analysis suggested that doses as low as 1 mg/kg resulted in circulating levels of antibody after a month, with a similar potency for neutralizing anthrax toxin in vitro as was seen with serum obtained from subjects who had been vaccinated with anthrax vaccine. These study results were presented at the 2006 Annual Meeting of the Infectious Diseases Society of America.

Preclinical studies suggest that Valortim has the potential to provide protection against anthrax infection when administered prophylactically (prior to the emergence of symptoms of anthrax infection) and also the potential to be administered therapeutically (once symptoms become evident).

About Anthrax

According to the Centers for Disease Control and Prevention, anthrax is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. Anthrax most commonly occurs in hoofed mammals and can also infect humans. Symptoms of disease vary depending on how the disease is contracted, but usually occur within seven days after exposure. The serious forms of human anthrax are inhalation anthrax, cutaneous anthrax, and intestinal anthrax. Initial symptoms of inhalation anthrax infection may resemble a common cold. After several days, the symptoms may progress to severe breathing problems and shock. Inhalation anthrax is often fatal, even if treated by antibiotics. Currently, antibiotics are the only drugs available for therapeutic or prophylactic use, and post-exposure prophylaxis is the only FDA-approved indication for such products. However, antibiotic therapy, while useful, is believed to be associated with a number of limitations, including: (1) lack of activity against the toxins produced by the B. anthracis bacteria (2) need for long-term dosing to achieve full protection, complicated by side effects and non-compliance (3) lack of efficacy when administered late in the anthrax disease cycle, and (4) lack of effectiveness against multi-drug resistant or genetically engineered strains of anthrax.

About PharmAthene, Inc.

PharmAthene (Amex: PIP) 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 programs include Valortim(TM) for the prevention and treatment of anthrax infection and Protexia(R) for the prevention and treatment of morbidity and mortality associated with exposure to chemical nerve agents. For more information on PharmAthene, please visit www.PharmAthene.com.

About Medarex, Inc.

Medarex is a biopharmaceutical company focused on the discovery, development and potential commercialization of fully human antibody-based therapeutics to treat life-threatening and debilitating diseases, including cancer, inflammation, autoimmune disorders and infectious diseases. Medarex applies its UltiMAb(R) technology and product development and clinical manufacturing experience to generate, support and potentially commercialize a broad range of fully human antibody product candidates for itself and its partners. More than 30 of these therapeutic product candidates derived from Medarex technology are in human clinical testing or have had INDs submitted for such trials, with seven of the most advanced product candidates currently in Phase III clinical trials. Medarex is committed to building value by developing a diverse pipeline of antibody products to address the world's unmet healthcare needs. For more information about Medarex, visit its website at www.medarex.com.

About USAMRIID

USAMRIID, located at Fort Detrick, Maryland, is the lead medical research laboratory for the U.S. Biological Defense Research Program, and plays a key role in national defense and in infectious disease research. The Institute's mission is to conduct basic and applied research on biological threats resulting in medical solutions (such as vaccines, drugs and diagnostics) to protect the war fighter. USAMRIID is a subordinate laboratory of the U.S. Army Medical Research and Materiel Command.

The information contained in this press release does not necessarily reflect the position or the policy of the United States government and no official endorsement should be inferred.

Statement on Cautionary Factors

For PharmAthene: 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"; "may"; "should"; "could"; or similar statements are forward-looking statements. PharmAthene disclaims, however, any intent or obligation to update these forward-looking statements. Risks and uncertainties include risks associated with the reliability of the results of the studies relating to human safety and possible adverse effects resulting from the administration of Valortim in humans, timely and successful development of an efficient and scalable manufacturing process, unexpected funding delays by NIAID/BARDA, unforeseen safety issues resulting from the handling of Bacillus anthracis, as well as risks detailed from time to time in PharmAthene's public disclosure filings with the U.S. Securities and Exchange Commission (the "SEC"). There can be no assurance that such development efforts will succeed or that other developed products will receive required regulatory clearance or that, even if such regulatory clearance were received, such products would ultimately achieve commercial success. Copies of PharmAthene's public disclosure filings are available from its investor relations department.

For Medarex: Except for the historical information presented herein, matters discussed herein 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"; "suggest"; "may"; "should"; "could"; or similar statements are forward-looking statements. Medarex disclaims, however, any intent or obligation to update these forward-looking statements, except as required by law. Risks and uncertainties include risks associated with the reliability of the results of the initial work conducted on Valortim relating to animal efficacy, human safety and likelihood of successful development of an efficient and scalable manufacturing process, unexpected funding delays by NIAID/BARDA, unforeseen safety issues resulting from the handling of Bacillus anthracis, unforeseen safety issues resulting from the administration of Valortim(TM) (MDX-1303) in human subjects, uncertainties related to product manufacturing as well as risks detailed from time to time in Medarex's public disclosure filings with the U.S. Securities and Exchange Commission (SEC), including its Annual Report on Form 10-K for the fiscal year ended December 31, 2006 and its quarterly reports on Form 10-Q. There can be no assurance that such development efforts will succeed or that other developed products will receive required regulatory clearance or that, even if such regulatory clearance were received, such products would ultimately achieve commercial success. Copies of Medarex's public disclosure filings are available from its investor relations department.

Medarex(R), the Medarex logo and UltiMAb(R) are registered trademarks of Medarex, Inc. All rights are reserved. "Valortim(TM) is a trademark of PharmAthene, Inc. All rights are reserved."

SOURCE PharmAthene, Inc.

Copyright © 2007 PR Newswire Association LLC. All Rights Reserved.