GTC Biotherapeutics Reports Progress in Preparations to Launch ATryn in the U.S.

FRAMINGHAM, Mass.--(Business Wire)--
GTC Biotherapeutics, Inc. ("GTC", NASDAQ: GTCB) has received $3 million as a
milestone payment from Lundbeck Inc. of Deerfield, IL, a subsidiary of H.
Lundbeck A/S, as a result of the approval of ATryn® (Antithrombin [Recombinant])
by the Food and Drug Administration. Lundbeck Inc. was previously known as
Ovation Pharmaceuticals, Inc. prior to being acquired by H. Lundbeck A/S.

Manufacture and release of product to support the commercial launch of ATryn has
been completed. An additional $1 million payment will be made by Lundbeck for
this inventory to support the ATryn launch in the second quarter of this year.

"Lundbeck is excited to lead the launch of ATryn in the United States," stated
Michael Burke, Chief Commercial Officer, Lundbeck Inc. "ATryn is a unique
product providing an important new treatment option for patients with hereditary
antithrombin deficiency who are undergoing surgery or childbirth procedures."

Lundbeck and GTC are also collaborating on a joint development plan for the
potential use of ATryn in heparin resistant patients. Cardiac surgery involving
use of a cardiopulmonary bypass machine, or CPB, requires that patients are
anticoagulated prior to going on bypass, in order to avoid clot formation and
other deleterious effects. Heparin is used to prevent the formation of blood
clots. Heparin`s ability to prevent clotting depends on the presence of
sufficient antithrombin in the bloodstream to achieve the desired anticoagulant
effect. It is estimated that over 20 percent of patients in CPB related
surgeries may exhibit heparin resistance. GTC has previously conducted studies
related to this indication.

Important Safety Information

ATryn® (Antithrombin [Recombinant]) was approved 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anticoagulation may be altered when ATryn is added or withdrawn.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, 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 anticipated further product inventory payment from
Lundbeck and plans for commercial launch and further 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 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.

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

Copyright Business Wire 2009