Thursday, May 7, 2009

“We are delighted to have reached this important milestone with the launch of ATryn in the US, which is the first transgenically produced therapeutic product to reach the marketplace,” stated Geoffrey F. Cox, Ph.D., GTC’s Chief Executive Officer and Chairman of the Board. “We look forward to working with Lundbeck to deliver this important new product.”

Antithrombin is a naturally occurring protein that helps regulate the blood clotting mechanism in the body. People with hereditary antithrombin deficiency lack sufficient antithrombin, putting them at increased risk for venous thromboembolic events (VTE), including pulmonary embolism and deep vein thrombosis, which can be life threatening, particularly in the high-risk situations of surgery or childbirth. Prior to the availability of ATryn, HD patients undergoing surgery or giving birth relied upon antithrombin derived from human plasma. ATryn is not formulated with human plasma proteins.

Approximately one in 2,000 to one in 5,000 people have hereditary antithrombin deficiency. By the age of 50, approximately 50 percent of people with hereditary antithrombin deficiency will have experienced a VTE.

Purified recombinant antithrombin has the same amino acid sequence as antithrombin derived from human plasma. Antithrombin (Recombinant) and plasma-derived antithrombin both contain six cysteine resudes forming three disulphide bridges and 3-4 linked carbohydrate moieties. The glycosylation profile of ATryn is different from plasma-derived antithrombin, which results in an increased heparin affinity. When assayed in the presence of excess heparin the potency of the recombinant product is not different from that of plasma-derived product.

GTC developed ATryn using its proprietary transgenic production technology. Transgenic production enables the development of recombinant forms of proteins, such as antithrombin, that otherwise are not practical to develop using other technologies.

Important Safety Information
ATryn® (Antithrombin [Recombinant]) was approved by the Food and Drug Administration on February 6, 2009 for the prevention of peri-operative and peri-partum thromboembolic events in hereditary antithrombin deficient patients. ATryn is contraindicated in patients with known hypersensitivity to goat and goat milk proteins. Allergic-type hypersensitivity reactions, including anaphylaxis, are possible. If these reactions occur during administration, treatment must be discontinued immediately and emergency treatment should be administered.

The anticoagulant effect of drugs that use antithrombin to exert their anticoagulation may be altered when ATryn is added or withdrawn. To avoid excessive or insufficient anticoagulation, coagulation tests suitable for the anticoagulant used (e.g., aPTT and anti-Factor Xa activity) are to be performed regularly, at close intervals, and in particular in the first hours following the start or withdrawal of ATryn. Additionally, patients must be monitored for the occurrence of bleeding or thrombosis in such situations.

The serious adverse reaction that has been reported in clinical studies is hemorrhage (intra-abdominal, hemarthrosis and post procedural). The most common adverse events reported in clinical trials at a frequency of >= 5% are hemorrhage and infusion site reaction.

For more information, including full prescribing information, go to www.lundbeckinc.com.

About GTC Biotherapeutics
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 the United States and Europe. ATryn is the first and only product produced in transgenic animals to be approved for therapeutic use anywhere in the world. 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 being developed for the treatment of hemophilia, and alpha-1 antitrypsin. GTC is developing a monoclonal antibody to CD20 with enhanced ADCC (antibody-dependent cell-mediated cytotoxicity), and a proprietary monoclonal antibody to CD137 with potential indications in oncology and autoimmune diseases. GTC is also developing a portfolio of follow-on biologic monoclonal antibodies. 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 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 Lundbeck’s commercial prospects for ATryn and the receipt of funds for product supply. 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 dependence upon the actions of collaboration partners. 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.

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