GTC BIOTHERAPEUTICS AND LAUREATE PHARMA ENTER STRATEGIC COLLABORATION

FRAMINGHAM, MA and PRINCETON, NJ – March 9, 2004 — GTC Biotherapeutics, Inc. (“GTC”, Nasdaq: GTCB) and Laureate Pharma L.P. (“Laureate Pharma”) have entered into a strategic collaboration for serving the clinical and commercial development, production, and purification needs of the biopharmaceutical industry. GTC and Laureate Pharma will coordinate their industry marketing efforts to provide strategic access to clients for recombinant protein production services required from small scale through tonnage quantities as well as for difficult-to-express products. GTC and Laureate Pharma will also be able to offer process design and development, in addition to downstream purification, for initial clinical material through commercial launch in accordance with the standards set by good manufacturing practices.

“We are pleased to enter this strategic collaboration with Laureate Pharma, who will provide GTC with access to large-scale downstream purification for commercial products, which is an important capability in the commercialization of our transgenic platform,” stated Geoffrey F. Cox, Ph.D., GTC’s Chairman of the Board and Chief Executive Officer. “In addition, our companies will also be able to offer a broad range of production technologies and manufacturing capabilities to external partners.”

“We are excited about this collaboration with GTC and view it as a good way to leverage the technical synergies of our organizations,” said Robert J. Broeze, Ph.D., President of Laureate Pharma. “Working together, Laureate Pharma and GTC offer the industry a broad menu of manufacturing solutions.”

Financial terms of the collaboration, which do not include any initial payments, were not disclosed.

About GTC Biotherapeutics

GTC Biotherapeutics is a leader in the development, production, and commercialization of therapeutic proteins through transgenic animal technology. GTC has three internal proprietary products in its pipeline and a portfolio of external program production opportunities. GTC’s lead program is ATryn®, its recombinant form of human antithrombin. A Market Authorization Application was recently accepted for review by the European Medicines Evaluation Agency for the use of ATryn® in patients with a hereditary antithrombin deficiency. In addition to the ATryn® program, GTC is developing a recombinant human serum albumin and a malaria vaccine. In its portfolio of external programs, GTC’s technology is used to develop transgenic production of its partners’ proprietary products, including both large-volume protein therapeutics as well as products that are difficult to produce in significant quantities from conventional bioreactor systems. GTC’s external program collaborations are developing transgenic versions of products such as monoclonal antibodies and immunoglobulin fusion proteins for conditions such as rheumatoid arthritis, HIV/AIDS and cancer. One of the external programs recently entered clinical trials with a transgenically produced product. Additional information is available on the GTC web site, http://www.gtc-bio.com.

About Laureate Pharma

Laureate Pharma is a privately held contract manufacturing services company with headquarters in Princeton, NJ. The company is dedicated to supporting the development and commercialization of pharmaceutical products for pharmaceutical and biopharmaceutical companies. Laureate Pharma’s biopharmaceutical division, located in Princeton, NJ, provides a wide range of product development services from process design and development to full-scale cGMP production, purification and aseptic filling, as well as corresponding analytical services and regulatory support. The division is focused on two active segments of the biopharmaceutical industry: monoclonal antibodies and recombinant protein products. Mammalian cells are grown in stirred-tank or hollow-fiber bioreactors for production of biopharmaceutical proteins, which are purified by state-of-the-art semi-automated chromatography systems. Laureate Pharma’s extended release technologies division, located in Totowa, NJ, supplies sustained release development, formulation and filling services through commercial scale at its cGMP manufacturing facility. For more information on Laureate Pharma, contact the company directly at (609) 919-3400, by email at support@laureatepharma.com or visit www.laureatepharma.com.

Forward Looking Statement for GTC Biotherapeutics

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 for collaborative work between GTC and Laureate Pharma, and the progress of GTC’s internal products and portfolio of external programs. 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 as 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 partners, including those in new marketing and strategic activities with GTC. 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.