FDA Approves Drug From Transgenic Goat Milk

ON FEB 6, the Food & Drug Administration approved the first human biological drug produced by a transgenic animal. The approval helped clinch the sale of the drug's marketer in the U.S., Ovation Pharmaceuticals, to Danish drugmaker Lundbeck.

The product, called ATryn, is a human antithrombin protein extracted from the milk of genetically engineered goats. It is expected to be available in the U.S. within a few months. The drug has been available in Europe since 2006.

Manufactured by Massachusetts-based GTC Biotherapeutics, ATryn is an anticoagulant intended to prevent blood clots during surgery or childbirth in patients with a rare blood disorder. The drug is an alternative to antithrombin derived from human plasma, which is in short supply.

The approval of ATryn was fast-tracked by FDA under the agency's orphan drug system, which is intended to encourage development of drugs to treat rare diseases that affect small populations. The fact that FDA chose a rare disease as the first test case for a drug produced by a transgenic animal has some critics of the technology concerned (C&EN, Jan. 26, page 25).

"FDA did a poor environmental impact statement, had virtually no transparency in its process, and had questionable statistics for the approval of ATryn," says Jaydee Hanson, policy director at the nonprofit International Center for Technology Assessment.

FDA approved ATryn after evaluating the safety and efficacy data from two studies that included 31 patients with hereditary antithrombin deficiency. Such a limited sample size yielded poor statistics about the safety of a transgenic animal drug, but FDA ultimately accepted the results for this new class of drugs because of the difficulty in finding patients with this particular genetic disease.

"GTC has some other drugs from transgenic animals in its pipeline for cancer that are going to be used for a lot of people. I would much rather have seen one of them be the first test case," Hanson says. "You would need a much larger sample size, and you could get a much larger sample size."

Meanwhile, Lundbeck has been looking to solidify a commercial platform in the U.S. for many years. ATryn was approved just days before the sale of Ovation, worth up to $900 million, was announced.

During a teleconference briefing, however, Lundbeck officials noted that the key drug driving the acquisition is Ovation's Sabril, a seizure medicine currently under review by FDA. Lundbeck, which focuses primarily on treatments for diseases of the central nervous system, also has high expectations for Ovation's Xenazine, a drug for treating Huntington's disease. "Ovation has an attractive broad pipeline on the market and a promising late-stage pipeline in the registration process," Ulf A. Wiinberg, chief executive officer of Lundbeck, said during the briefing. He emphasized Ovation's "strong track record in development of products and in getting products approved with FDA."