ATryn® (Antithrombin [Recombinant]) Approved by the FDA

ATryn® (Antithrombin [Recombinant]) Approved by the FDA

Only recombinant option for patients with hereditary antithrombin deficiency, a rare and potentially life-threatening condition

Framingham, MA, and Deerfield, IL, February 6, 2009 - GTC Biotherapeutics ("GTC", NASDAQ: GTCB) and OVATION Pharmaceuticals, Inc. announced today that the U.S. Food and Drug Administration (FDA) approved ATryn® (Antithrombin [Recombinant]) for the prevention of peri-operative and peri-partum thromboembolic events in hereditary antithrombin deficient patients. It is not indicated for treatment of thromboembolic events in hereditary antithrombin deficient patients. ATryn is the first ever transgenically produced therapeutic protein and the first recombinant antithrombin approved in the U.S. Along with the approval of ATryn, the FDA's Center for Veterinary Medicine also approved GTC's New Animal Drug Application, the first of its kind to regulate genetically engineered animals. This is now required for a recombinant technology used to develop transgenic animals, such as the goats that produce recombinant antithrombin. GTC has granted OVATION the right to market ATryn in the U.S. 1 and pursue further clinical development. The companies expect ATryn to be available in the second quarter of 2009.

People with hereditary antithrombin deficiency are at increased risk for venous thromboembolic events, including pulmonary embolism and deep vein thrombosis, which can be life-threatening, particularly in high risk situations.2 Antithrombin is a natural anticoagulant that plays an important role in controlling the formation of blood clots.2 Purified recombinant antithrombin has the same amino acid sequence as antithrombin derived from human plasma.3

"The approval of ATryn marks a significant milestone in the development of this innovative recombinant technology and delivers a new therapeutic option to benefit hereditary antithrombin deficient patients who are undergoing surgery or childbirth procedures," said Geoffrey F. Cox, Ph.D., GTC's Chairman and Chief Executive Officer. "Advancing this novel technology from the early days of demonstrating its capability to the daily practice of producing a safe and efficacious product for the U.S. and the European Union, is a testament to the persistence and capability of our employees."

ATryn was developed to provide a safe and consistent supply of recombinant antithrombin.3

"With FDA approval of ATryn, we can help ensure that patients with hereditary antithrombin deficiency, a rare clotting disorder associated with severe complications, have access to much needed therapy," said Jeffrey S. Aronin, OVATION President and Chief Executive Officer. "Bringing ATryn to market gives us the opportunity to make a meaningful difference in the lives of people with this rare disorder and is consistent with Ovation's mission of addressing unmet medical needs of small patient populations."

The safety and efficacy of ATryn was established in clinical studies conducted in hereditary antithrombin deficient patients with a history of thromboembolic events in the U.S., Europe and Canada. During these studies, ATryn was shown to prevent the formation of clinically overt thromboembolic events. Post-marketing studies will be performed to assess safety and immunogenicity after repeat dosing.

The prevalence of hereditary antithrombin deficiency in the general population is approximately one in 2,000 to one in 5,000.4,5 Half these patients may experience a thrombosis before 25 years of age6 and, based on a study, up to 85 percent may suffer a thromboembolic event by age 50.7

About ATryn

ATryn is the first recombinant antithrombin product approved in the world and the first antithrombin product that has been approved through the centralized procedure in the European Union.8 It is now also the first recombinant antithrombin product approved by the FDA.

Important Safety Information

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

About Transgenic Production

The process for producing ATryn involves scientists inserting DNA for the human antithrombin protein into a single-celled goat embryo. This embryo is implanted into a surrogate doe. The resulting transgenic offspring are able to produce high levels of antithrombin in their milk. This protein is collected and purified from the milk to produce ATryn, which is administered to patients by intravenous infusion.

About GTC Biotherapeutics

GTC Biotherapeutics develops, supplies, and commercializes therapeutic proteins produced through transgenic animal technology. 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 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,

This press release contains forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995, including without limitation statements regarding the commercial launch of ATryn in the U.S. and the prospects for further clinical development of ATryn. 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 uncertainties associated with dependence upon the actions of collaboration partners and regulatory 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.

About OVATION Pharmaceuticals

OVATION is a fast growing biopharmaceutical company that develops and commercializes medically necessary therapies to satisfy unmet medical needs for patients with severe illnesses. Headquartered in Deerfield, Ill., with products available in more than 85 countries, OVATION is committed to having a significant impact on patients' lives through its focus on central nervous system (CNS), hematology/oncology, and hospital-based therapies. The company expects five new launches over the next three years, fueled largely by its late-stage CNS pipeline, which is one of the most robust in the industry. OVATION has been recognized for excellence in the global pharmaceutical and biotechnology industries with the 2006 and 2007 "Pharma Company of the Year" award from Scrip magazine for small to mid-sized enterprises. More information about the company, its products and full prescribing information may be found at

GTC Biotherapeutics, Inc.
Thomas E. Newberry
Vice President, Corporate Communications
(508) 370-5374 or [email protected]

OVATION Pharmaceuticals, Inc.
Sally Benjamin Young
Vice President of Communications
(847) 727-3265 or [email protected]
ATryn Press Release References:

The National Alliance for Thrombosis and Thrombophilia. Antithrombin Deficiency: An In-Depth Guide for Patients and Health Care Providers. 2006. - A Resource for Information on Hereditary Antithrombin Deficiency (HD).
Maclean PS, et al. Hereditary and Acquired Antithrombin Deficiency: Epidemiology, Pathogenesis and Treatment Options. Drugs 2007; 67 (10) : 1429-1440.
Patnaik MM, Moll S. Inherited antithrombin deficiency: a review. Haemophilia. 2008 Nov;14(6):1229-39.
Lane DA et al. Inherited thrombophilia: Part 1. Thromb Haemost 1996; 76: 651-62.
Anderson F, et al. Risk Factors for Venous Thromboembolism. Circulation 2003; 107;I-9-I-16.