“We are pleased to continue to support PharmAthene as it develops Protexia®,” stated Geoffrey F. Cox, Ph.D., GTC’s Chairman and Chief Executive Officer. “The constraint in supplying BChE from either human plasma sources or other recombinant systems is an excellent example of transgenic production enabling development of otherwise difficult to express proteins.”

While the utility of human plasma derived butyrylcholinesterase (BChE) to protect against nerve agent toxicity is well documented, a major limitation hindering its commercial development has been the inability to produce commercial quantities due to a limited availability of appropriate blood supplies, low levels of the protein in plasma, and low production yields using traditional biotechnology methods. Protexia® overcomes these limitations by enabling substantially larger production yields than are possible using other expression systems or through purification of the native protein from human plasma. Transgenic production and manufacturing is estimated to be capable of supplying sufficient rBChE to make Protexia® available for use by the military and civilian populations.

About Nerve Agents
Organophosphate nerve agents, or anti-cholinesterase agents, cause toxicity by binding to and inhibiting acetylcholinesterase, an enzyme in the body that is essential for nervous system function. This leads to increases in acetylcholine and “cholinergic crisis” that can cause loss of muscle control, respiratory failure, paralysis, convulsions, permanent brain damage and eventually death.

These so-called nerve gases, which are actually all liquids at room temperature, are lethal in low quantities when inhaled or absorbed through the skin. Nerve agents can be classified as either G-agents (sarin, soman, tabun) or V agents (VX), both of which are exceedingly volatile and toxic.

About Protexia®: Recombinant Human Butyrylcholinesterase
Protexia® is a pegylated form of recombinant human butyrylcholinesterase (rBChE), a potent organophosphate (OP) scavenger protein produced in the milk of transgenic goats, which is being developed for use as a prophylactic and therapeutic against acute organophosphate (OP) nerve agent toxicity. PharmAthene’s development of Protexia® is being funded by a multi-year contract from the Department of Defense (DoD) U.S. Army Space and Missile Command. For more information on PharmAthene, please visit www.PharmAthene.com.

About GTC Biotherapeutics, Inc.
GTC Biotherapeutics develops, supplies, and commercializes therapeutic proteins produced through transgenic animal technology. ATryn®, GTC’s recombinant human antithrombin, has been approved for use in Europe and has begun the review process in the United States under a rolling Biologics License Application. In addition to ATryn®, GTC is developing a portfolio of recombinant human plasma proteins with known therapeutic properties. These proteins include recombinant forms of human coagulation factors VIIa, VIII, and IX, which are used for the treatment of hemophilia, and alpha-1 antitrypsin. GTC also has a monoclonal antibody portfolio that includes a monoclonal antibody to CD20 and a monoclonal antibody to CD137. GTC’s intellectual property includes a patent in the United States through 2021 for the production of any therapeutic protein in the milk of any transgenic mammal. GTC’s transgenic production platform is particularly well suited to enabling cost effective development of proteins that are difficult to express in traditional recombinant production systems as well as proteins that are required in large volumes. Additional information is available on the GTC web site, http://www.gtc-bio.com.

This press release contains forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995, including without limitation statements regarding the potential efficacy of Protexia® for biodefense and PharmAthene’s potential production requirements for the development of Protexia® for the Department of Defense. Such forward-looking statements are subject to a number of risks, uncertainties and other factors that could cause actual results to differ materially from future results expressed or implied by such statements. Factors that may cause such differences include, but are not limited to, the risks and uncertainties discussed in GTC's most recent Annual Report on Form 10-K and its other periodic reports filed with the Securities and Exchange Commission, including the risks and uncertainties associated with the development of therapeutic proteins and dependence upon the actions of partners and regulatory and other governmental agencies. GTC cautions investors not to place undue reliance on the forward-looking statements contained in this release. These statements speak only as of the date of this document, and GTC undertakes no obligation to update or revise the statements, except as may be required by law. GTC obtained the information in this press release regarding Protexia, PharmAthene and its business, other than its agreement with GTC, from PharmAthene’s published information; and GTC has not independently verified any of such information.

CONTACT:
GTC Biotherapeutics, Inc.
Thomas E. Newberry
Vice President, Corporate Communications
(508) 370-5374 or tom.newberry@gtc-bio.com