FRAMINGHAM, MA and PARIS, FRANCE – May 8, 2008 -- GTC Biotherapeutics, Inc. ("GTC", Nasdaq: GTCB) and LFB Biotechnologies, a wholly owned subsidiary of LFB S.A. (Laboratoire francais du Fractionnement et des Biotechnologies S.A.) have agreed to include GTC’s recombinant human alpha-1 antitrypsin program in their strategic collaboration for the development of selected recombinant plasma proteins and monoclonal antibodies. In accordance with the existing collaboration agreement, LFB will be providing additional funding to support GTC’s work in the recombinant human alpha-1 antitrypsin program for 2008.

“Together with LFB Biotechnologies, we are developing a broad portfolio of recombinant plasma proteins with significant market opportunities which are uniquely supported by our production technology,” stated Geoffrey F. Cox, Ph.D., GTC’s Chairman and Chief Executive Officer. “The capabilities of our transgenic system are well suited to therapeutic proteins where expression rates, production volume, or cost are key considerations.”

“Thanks to this collaboration with GTC, the world leader in transgenic animal technology, LFB has access to the innovative production platform we need to be able to expand our market base in Europe and potentially beyond”, stated Christian Béchon, LFB’s Chairman and Chief Executive Officer. “We are excited to be working on a broad portfolio of recombinant plasma proteins and monoclonal antibodies to provide the opportunity for expanded patient access to these products.”

Summary of Collaborative Programs
In addition to the recombinant alpha-1 antitrypsin program, the GTC/LFB Biotechnologies collaboration includes recombinant factor VIIa, recombinant factor IX, and a monoclonal antibody to CD20. The factor VIIa and factor IX programs are targeted to the treatment of bleeding in hemophilia. The monoclonal antibody to CD20 is targeted at the treatment of B-cell non-Hodgkin's lymphoma, B-cell leukemia and rheumatoid arthritis.

About LFB Group
With 2007 sales of 322 million euros ($496 million) and a R&D budget of 48 million euros ($74 million), LFB is the third largest pharmaceutical company supplying drugs to hospitals in France and a major European producer of plasma-derived medicinal products. LFB provides to healthcare professionals a wide range of 20 plasma-derived medicinal products in three therapeutic fields: Hemostasis, Intensive Care and Immunology. LFB’s medicinal products are prescribed to address emergencies but also to manage chronic diseases that require lifelong treatment. With 1380 employees, among which 230 are in R&D, LFB is recognized as one of the major European players in the field of therapeutic proteins with expertise in protein downstream processing, characterization as well as biological safety and viral clearance. LFB focuses its discovery and development activities on monoclonal antibodies and therapeutic proteins for rare and severe diseases. Ideally placed to become a driving force in new technological and therapeutic fields, LFB can use its technology platform to develop highly cytotoxic antibodies while its R&D portfolio contains high-potential projects calling on innovative technology.

About GTC Biotherapeutics
GTC Biotherapeutics develops, supplies, and commercializes therapeutic proteins produced through transgenic animal technology. ATryn®, GTC’s recombinant form of human antithrombin, is the first therapeutic protein produced transgenically to have obtained a regulatory approval. ATryn® is approved in Europe for the treatment of hereditary antithrombin deficient patients undergoing surgery. GTC is in the process of filing for review of ATryn® for market authorization for a similar indication in the U.S. 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 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 level of funding and anticipated development of the programs in the collaboration. 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 conducting clinical studies, and the risks and uncertainties associated with dependence upon the actions of regulatory agencies and 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. GTC specifically disclaims responsibility for information describing LFB and its business other than the joint programs governed by the agreement with GTC.


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

LFB
Sandrine Charrières
Corporate Communications Director
+33 (1) 69827280 or charrieres@lfb.fr