GTC Biotherapeutics, Inc has completed its submission of the final portion of the Biologics License Application, or BLA, for ATryn in the United States. The final portion of the BLA submission includes all of the clinical safety and efficacy data generated from studies of ATryn, including the pivotal study supporting product licensure.

ATryn is GTC's recombinant form of human antithrombin, a plasma protein with anticoagulant and anti-inflammatory properties. The BLA requests market authorization for the use of ATryn in the prophylactic treatment of deep vein thrombosis and other thromboembolisms in patients with hereditary antithrombin deficiency, who are undergoing high risk surgical and childbirth procedures. There are no other recombinant forms of antithrombin available to treat this patient population.

GTC has requested Priority Review. Priority Review is a procedure the US Food and Drug Administration, or FDA, reserves for products that are intended to treat serious and/or potentially life threatening events and has the potential to fulfil an unmet medical need. ATryn has already been granted Orphan Drug designation, as well as Fast Track status by the FDA. Assuming that Priority Review is granted, GTC anticipates the FDA reaching a decision on the BLA filing in the first quarter of 2009. A definitive agreement has been signed with Ovation Pharmaceuticals, Inc for commercialization and development rights in the US.

ATryn has been approved for use in a similar indication in the European Union. LEO Pharma A/S is marketing ATryn in Europe and is conducting further clinical development.

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.