US FDA gives green light to pigs genetically engineered to lack allergenic sugar
The US Food and Drug Administration has approved the first genetically modified animal for both human food consumption and possible biomedical uses, the agency announced Dec. 14. The animals are a line of domestic pigs engineered to lack the sugar galactose-α-1,3-galactose—commonly called alpha-gal—on the surface of their cells. The pigs could provide a source of red meat for people with alpha-gal syndrome who are allergic to alpha-gal sugar in conventional red meat.
The pigs could also be used to produce drugs, such as the blood thinner heparin, that don’t contain the allergen, or tissues and organs that are less likely to be rejected in patients receiving transplants.
Called GalSafe pigs, the animals are being developed by Revivicor, which aims to use the pigs to produce tissues and organs for transplantation into humans. For now, the company plans to produce a relatively small number of pigs per year and sell the meat only by mail order, according to the FDA.
The FDA did not evaluate whether the product prevents or eliminates allergic reactions when eaten by people with alpha-gal syndrome. Rather, the agency evaluated the safety of the genetic alteration in GalSafe pigs and “determined that food from GalSafe pigs is safe for the general population to eat,” Steven Solomon, director of the FDA’s Center for Veterinary Medicine, said during a call with reporters. “The intentional genetic alteration is durable and stable so that there is no detectable alpha-gal in any of the cells or tissues of these pigs,” he said.
Alpha-gal syndrome is on the rise in the US. Most people afflicted with the disorder have been bitten by a species of tick called the lone star tick, which has been spreading throughout the US, Solomon said. The tick transfers alpha-gal sugar into the host. The sugar triggers an immune reaction in some people that makes them allergic to red meat and other products, such as cosmetics and drugs, made from mammals. The severity of the reaction varies from person to person.
The FDA’s approval of GalSafe pigs does not clear them for use in medical products, but it opens the door for that possibility. Developers seeking to use the pigs for such purposes must obtain additional approval from the agency for each specific medical use.