First transgenic drug approved
Despite a false-start in February, the first drug developed from transgenic technology has been approved for use in the EU by the Committee for Medicinal Products for Human Use (CHMP), part of the European Medicines Agency. The drug, derived from transgenic goats, will treat people who lack a gene needed to eliminate blood clots. The drug, ATryn, contains antithrombin alfa, normally produced naturally in the human body. When blood clots spontaneously occur, the body breaks them down with antithrombin alfa before they become harmful. However, some people lack the gene responsible for creating antithrombin alfa, leaving them susceptible to thrombosis, which can be serious during surgery or childbirth. People with antithrombin deficiency would normally be given antithrombin alfa derived from blood plasma as a prophylactic or during key moments, such as surgery, to prevent the blood clots appearing. These people now have an alternative. The CHMP opinion gives approval for the drug to be used during surgery, but yet not for pregnant women. The technique used to make ATryn is novel. The gene for antithrombin alfa is spliced onto goat DNA. The goat then expresses the antithrombin alfa in its milk. The milk can then be collected, and the antithrombin alfa extracted. Similar techniques are in development to manufacture a large number of further transgenic products. The decision is a landmark for the biotechnology and medical industries. While antithrombin deficiency is a rare disease, affecting only one in 3,000 to 5,000 people, products made from blood plasma are necessarily expensive, limited by the number of blood donations available. Replacements will save lives and alleviate competition for blood plasma - a scarce resource. In a year, a single transgenic goat can produce antithrombin alfa equivalent to 90,000 blood donations. New products like ATryn will further reduce competition on blood plasma products. In February, the CHMP decided that ATryn could not be approved because of a limited test sample size and a slight difference between the final product and the drug used in tests - the product will be filtered an additional time. The company marketing ATryn, Genzyme Europe, on behalf of manufacturers GTC Biotherapeutics, requested the CHMP re-assess their initial decision. On re-examination, the CHMP decided that the benefits of ATryn outweigh the risks. The full opinion reads: 'ATryn is indicated for the prophylaxis of venous thromboembolism in surgery of patients with congenital antithrombin deficiency. ATryn is normally given in association with heparin or low molecular weight heparin.' Heparin is a common anti-coagulant drug. Professor Isobel Walker, Consultant Haematologist at Glasgow Royal Infirmary, applauded the decision. 'It is a good day for European patients with congenital antithrombin deficiency and for their physicians. ATryn provides an alternative to treatment with human plasma derived antithrombin and gives physicians and patients more choice in how they will be treated,' she said.