EMEA blocks use of first transgenic drug
The Committee for Medicinal Products for Human Use (CHMP), part of the European Medicines Agency (EMEA), has issued a negative opinion relating to the drug Atryn, which is the first drug manufactured through transgenic technology that has been submitted for approval for the mass market in either the US or Europe. Transgenic technology involves introducing a gene or genes from one individual into the cellular DNA of another individual, even who may be from a different species. Atryn, manufactured by GTC Therapeutics in the US, contains anti-thrombin (AT), which has anticoagulant and anti-inflammatory properties. The drug occurs naturally in humans and is an essential part of the body's ability to eliminate blood clots. Around one in 5,000 people are born without the ability to produce AT, and are susceptible to blood thickening as a consequence. This could be life-threatening in situations such as childbirth or surgery. To make Atryn, the human gene responsible for AT in healthy humans is spliced onto goat DNA. This causes the production of AT by the goat, but the gene is regulated so that the AT is only expressed in the goat's milk. People taking Atryn would expect to have their anti-clotting deficiencies compensated, and so lead a more normal life. The drug could also be used during surgery to compensate for a lack of AT at specific times. The way the drug is produced is not new. The first genetic recombinant goat was born 15 years ago, and is now one of a heard of 57, stabled near Boston. People suffering from an absence of AT would normally obtain their AT from human blood plasma. 'It takes just 18 months to produce a lactating animal and in a single year one goat produces the equivalent of 90,000 blood collections', GTC's CEO, Geoffrey Cox, told the BBC. The EMEA decided to block the marketing of Atryn for two reasons - firstly it found the clinical sample to be too small, and secondly, the drug proposed for the market would undergo an additional filtration step, and so not be identical to the drug used in trials. GTC was trialled using 14 cases. Five had AT deficiencies due to surgery and were included in the trial as part of a 'compassionate use programme', which makes the drug available to specific patients that doctors believe need it, while the other nine had the AT deficiency from birth. According to the EMEA opinion, 'Only 5 surgical cases were considered. The CHMP considered this number to be too small [...]. The results in patients treated in the compassionate use programme and at childbirth could not be used to support the proposed use in patients undergoing surgery.' The EMEA also commented that although no ill effects could be expected from those taking Atryn as part of a clinical trial, 'it is possible that patients develop antibodies (proteins in response to Atryn). The CHMP considered that the company did not carry out enough studies looking for the development of antibodies.' GTC now has 15 days to submit a request for the EMEA to re-examine its opinion. Atryn is the first of a host of drugs that have been manufactured using genetic recombination techniques, and are awaiting clearance to be taken to market. There is great potential for such drugs to improve the quality of human life. Products are expected soon that will treat a variety of conditions, including angioedema and certain cancers. In the future, drugs manufactured in such a way could be the norm, and not the novelty they are now.
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