GTC Biotherapeutics, Inc. and Ovation Pharmaceuticals, Inc. have entered into a collaboration agreement to develop and market ATryn in the United States.

ATryn is GTC's recombinant form of human antithrombin, a plasma protein with anticoagulant and anti-inflammatory properties. The agreement includes $257 million in potential payments to GTC for meeting clinical, regulatory, and sales milestones.

The collaboration includes development and commercialization of ATryn in the hereditary anti-thrombin deficiency, or HD, indication. The milestone payments include a total of $9 million through approval of ATryn for HD in the US, including $3 million paid upon closing and an additional $2 million expected to be received in 2008. The collaboration also plans for further development in larger market acquired anti-thrombin deficiencies such as the treatment of heparin resistance in patients undergoing surgery requiring cardiopulmonary bypass and the treatment of disseminated intravascular coagulation associated with severe sepsis.

"We are very pleased to be working with Ovation to develop ATryn in the US market," stated Geoffrey F Cox, Ph.D., GTC's chairman of the board and chief executive officer. "Ovation's track record, award winning commercial capabilities, and their focus on haematology, make them an excellent collaboration partner as well as a strong match to maximize ATryn's potential as the market's only recombinant anti-thrombin".

GTC will be responsible for production of ATryn and will receive a transfer price on commercial product, a royalty on net sales, and a payment for product used in clinical trials. As the collaboration proceeds with the acquired deficiencies, Ovation will fund GTC's anticipated costs of clinical development. Ovation will be responsible for sales and marketing of ATryn in the US, including all launch activities.

ATryn has already been granted both Orphan Drug designation and Fast Track status for HD by the US Food and Drug Administration. GTC has submitted the first part of a rolling Biologics License Application, or BLA, for the use of ATryn in preventing deep vein thrombosis in HD patients undergoing high risk surgical procedures and in childbirth. Filing of the second and final part of this BLA submission is planned for the third quarter.

Assuming GTC's request for priority review is granted, a decision on market approval by the FDA is anticipated in the first quarter of 2009.

ATryn has been approved for use in the European Union for HD patients undergoing surgical procedures. LEO Pharma A/S is commercializing and developing ATryn in Europe. LEO is already conducting a phase II dose ranging study of ATryn as a potential treatment for DIC associated with severe sepsis. GTC will have access to LEO's European phase II study results for use in clinical and regulatory development in the US, which is estimated to be a $2 to 3 billion market. An international phase III programme is anticipated, in which LEO Pharma and Ovation will share clinical development costs required for approval for this indication in the US and Europe.

Ovation and GTC also expect to develop ATryn as a supplement to restore heparin responsiveness in heparin resistant patients. Coronary artery bypass graft and related surgeries where a cardiopulmonary bypass machine, or CPB, is used requires that patients are anticoagulated prior to going on bypass, in order to avoid clot formation. Heparin is used to prevent the formation of blood clots in the CPB. Heparin's ability to prevent clotting depends on the presence of sufficient anti-thrombin in the bloodstream to achieve the desired anticoagulant effect. Over 20 per cent of patients in CPB related surgeries exhibit heparin resistance. GTC has conducted studies related to this indication and one or more additional clinical trials may be required to obtain FDA approval.

The agreement between GTC and ovation, which is expected to close within 30 days, is subject to certain closing conditions, including Hart-Scott-Rodino review.

Ovation is a fast-growing biopharmaceutical company that develops, manufactures and markets medically necessary therapies to satisfy unmet medical needs for patients with severe illnesses.