Animal's eggs contain an enzyme engineered to treat a rare disease. The US Food and Drug Administration (FDA) has approved a chicken genetically engineered to produce a drug in its eggs. The drug, Kanuma (sebelipase alfa), is a recombinant human enzyme marketed by Alexion Pharmaceuticals. It replaces a faulty enzyme in people with a rare, inherited condition that prevents the body from breaking down fatty molecules within its cells. With the 8 December FDA approval, Kanuma joins a small group of ‘farmaceuticals’ on the US market. In 2009, the agency approved genetically modified goats that produce an anticoagulant called ATryn in their milk. And last year, the FDA okayed a drug to treat hereditary angioedema that is produced by transgenic rabbits. The FDA’s latest decision “shows that the ATryn goats weren’t just a one-off,” says Jay Cormier, a lawyer at Hyman, Phelps & McNamara in Washington DC and a former scientific reviewer for the FDA. “The process can function for more than just one particular unique case.” The agency moved quickly to consider Kanuma, giving it a priority review, orphan drug status and a breakthrough therapy designation. The disease that it is designed to treat, called lysosomal acid lipase deficiency (LAL-D) , causes fat to accumulate in sufferers’ livers, spleens and vasculature. A form of the disease that strikes infants is quickly fatal. A second form that affects older patients causes liver enlargement, fibrosis, and cirrhosis, as well as cardiovascular disease. “Before we had this drug, we didn’t have any treatment for the patients that really addressed the underlying biochemical defect in the disorder,” says Barbara Burton, a paediatrician with the Northwestern University Feinberg School of Medicine in Chicago, Illinois. Clinicians could only provide nutrition and supportive care to infants, says Burton, who worked with Alexion to conduct the clinical trials. Older patients are treated with statins — which don’t address the fatty buildup in the liver. Unlike the genetically engineered AquAdvantage salmon that the FDA approved last month, the transgenic chickens that produce Kanuma are not intended to enter the food supply. But just as with the AquAdvantage salmon, the FDA considers the chicken’s genetic modifications to be a new animal drug. Because every cell in the modified chicken contains altered DNA, the FDA “asserts its jurisdiction over the entire chicken,” says Cormier. Under its process for considering new animal drugs, the FDA examined whether altering the chickens' DNA would harm them, and whether the modified DNA was stable as it passed to new generations of chickens. The FDA says that the chickens are not likely to accidentally enter the food supply or adversely affect the environment, because they are raised in indoor facilities. William Muir, a geneticist at Purdue University in West Lafayette, Indiana, praised FDA's decision to approve the transgenic chickens. “The FDA apparently is opening the gates, and they’re allowing these [genetically engineered] products on the market,” he says. “The floodgates are opening, and I can’t wait to see what comes next.” For the best commenting experience, please login or register as a user and agree to our Community Guidelines. You will be re-directed back to this page where you will see comments updating in real-time and have the ability to recommend comments to other users.
