Managed Care - March 2009 - (Page 47) TOMORROW’S MEDICINE has been available in the United States for many years), the approval of ATryn may signal the start of a disruptive technologic breakthrough, as this is the first approved transgenic therapeutic protein in the United States. ATryn is indicated for the prevention of perioperative and peripartum thromboembolic events in patients with hereditary antithrombin deficiency. HD is a genetic disorder leading to excessive clotting because of a lack of normal antithrombin activity. Antithrombin (AT) is a 432 amino acid protein that regulates thrombin and the downstream clotting processes. There are two distinct types of HD — Type I and Type II. Type I is a quantitative deficiency, meaning there are low absolute levels of AT. Type II is a functional deficiency, meaning the existing AT is not able to act on the clotting system because of a defect in the structure of the AT. Both types of HD are the result of mutations or point deletions in the DNA that regulates the manufacture or structure of the protein. HD is diagnosed based on two tests, one measuring the quantity and the other measuring the function of AT. It is a diagnosis of exclusion — other causes of reduced AT such as liver disease or nephritic syndrome must be absent. Treatment of HD depends on the risk of a thromboembolic event. If a patient has a venous clot, acute anticoagulation agents are used. If an HD patient has had multiple episodes of thrombosis or embolism, long term anticoagulation may be desired. AT becomes the treatment of choice as a prophylactic agent during periods of high risk of thrombosis. There are two forms of AT available — the plasma products taken from pooled whole blood and the new ATryn, transgenic recombinant antithrombin. The amino acid sequences The author is a director in the value-based health department at Genentech Inc. During the three years before taking the Genentech position, he received honoraria or other financial benefits from: Amgen, Amylin Pharmaceuticals, AstraZeneca, Biogen Idec, Centocor, Galderma, GlaxoSmithKline, Johnson & Johnson, Merck, Novartis, Novo Nordisk, Pfizer, Procter & Gamble, Q-Med, Sanofi-Aventis, Teva Pharmaceuticals Industries, UCB, and Wyeth. The views expressed in Tomorrow’s Medicine are the author’s alone. of ATryn and human antithrombin are indistinguishable. Dose is dependent on pretreatment functional AT activity level, weight, and the patient’s reason for therapy (pregnancy dosing is different from surgical dosing). The goal of treatment is to restore and maintain AT activity levels between 80 percent and 120 percent of normal. Treatment is initiated approximately 24 hours before surgery or before delivery. Frequent monitoring is needed after surgery and once or twice daily thereafter. ATryn is expected to be available in the second quarter of 2009. The future Although the mammary epithelial cell does not typically express antibodies, GTC Biopharmaceuticals has found that the intracellular machinery needed to properly fold and assemble the heavy and light chains of antibodies are functional within these cells. Transgenic goats can be used to produce a wide variety of biologically active recombinant proteins and antibodies. They include both small and large proteins as well as complex glycosylated proteins containing specific sugars attached at precise sites in the mature protein molecule. The types of antibodies that can be created using transgenic animals include mouse antibodies, partially humanized antibodies, and fully human antibodies. Of intense interest is the creation of proteins that can be fused to the targeting sequence of an antitumor antibody. This next generation of biotechnology is certain to be a future topic of Tomorrow’s Medicine! MC ADVERTISING INDEX ACADEMY OF MANAGED CARE PHARMACY 21st Annual Meeting 18 AMGEN, INC. Neulasta C2,1 FOREST LABORATORIES Bystolic 25–26 GENENTECH, INC. Corporate 4, 38 NOVO NORDISK, INC. Levemir C3,C4 PRESCRIPTION SOLUTIONS Corporate 9 MARCH 2009 / MANAGED CARE 47
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