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New Drug From Genetically Engineered Goat

Feb. 6, 2009 -- The FDA today approved ATryn, the first drug made in genetically engineered animals.

ATryn, which is given by infusion, is for people with a rare condition called hereditary antithrombin deficiency. About 1 in 5,000 people in the U.S. have that condition, according to the FDA.

People with hereditary antithrombin deficiency don't make enough antithrombin, an anticlotting compound. That shortfall of antithrombin puts patients at risk of life-threatening blood clots, especially during pregnancy, childbirth, surgery, or prolonged bed rest.

ATryn comes from goats that were genetically engineered to have human antithrombin, an anticlotting protein found in healthy people, in their milk.

Patients won't drink that goat milk. The human antithrombin is extracted from the goats' milk to make ATryn.

The FDA approved ATryn based on two studies of 31 patients with hereditary antithrombin deficiency to prevent dangerous blood clots before, during, or after surgery or childbirth. All but one of those patients had a history of such clots, which are likely to recur in high-risk situations if left untreated. Only one of the 31 patients had a clot when treated with ATryn.

The most commonly reported adverse reactions to ATryn were hemorrhage and infusion site reactions. Those reactions occurred in about 5% of the patients studied, according to the FDA.

The FDA's Center for Veterinary Medicine also found that the genetic engineering process didn't have adverse effects on seven generations of the goats and that GTC Biotherapeutics has adequate procedures in place to ensure that food from those goats doesn't enter the food supply; it also found that the goats won't harm the environment.

The FDA's approval of ATryn is in line with the recommendation made by an FDA advisory committee last month.

GTC Biotherapeutics developed ATryn and granted ATryn's U.S. marketing rights to Ovation Pharmaceuticals. In a joint news release, GTC Biotherapeutics and Ovation Pharmaceuticals note that ATryn is approved for the prevention of clotting events around the time of surgery and childbirth in patients with hereditary antithrombin deficiency, but not to treat clots in those patients.

Other treatment for hereditary antithrombin deficiency involves taking blood thinners and getting infusions of human antithrombin that's been extracted from donated human blood.