FDA approves genetically altering pigs, to potentially make food, drugs, and transplants safer

Genetically engineering pigs so they lack a certain sugar on the surface of their cells that triggers meat allergies or organ rejection won approval from the Food and Drug Administration Monday. The regulatory clearance — the first of an intentional genomic alteration in a product with both food and medical uses — means the animals could be safer sources of not just food but also treatments such as the blood-thinner heparin.

“Today’s first ever approval of an animal biotechnology product for both food and as a potential source for biomedical use represents a tremendous milestone for scientific innovation,” FDA Commissioner Stephen Hahn said in a statement.

There have been four previous approvals for such genetic engineering in animals, three for biomedical purposes and one for food, but none for both biomedicine and food, Steven Solomon, director of the FDA’s Center for Veterinary Medicine, said in a conference call with reporters.

GalSafe pigs, named for their lack of detectable alpha-gal sugar, could potentially provide tissues and organs for patients without the danger of rejection caused by the presence of the sugar in cross-species procedures known as xenografts or xenotransplantation. Alpha-gal is considered a primary cause of rejection, Solomon said, but he was hesitant to say it is the only source. 

“I think that people need to be careful,” Solomon said. “That’s why in part, it’s going to require further evaluation for xenotransplantation, xenograft, or the other activities by the medical products centers and FDA.”

People with Alpha-gal syndrome, a condition that causes mild to severe allergic reactions to alpha-gal sugar found in the red meats beef, pork, and lamb, might also benefit. The allergic reaction, recently identified in the United States, occurs after a Lone Star tick bites and then transmits alpha-gal sugar into a person’s body. Some people develop an immune reaction that later erupts into mild to severe allergic responses after eating the alpha-gal sugar in meat. 

The FDA did not test food safety specifically for people who have the syndrome, nor did the agency evaluate the pigs for use in transplantation or implantation into humans. Any developers hoping to make medical products based on GalSafe pigs would have to seek approval from the FDA before any organs, implants, or drugs could be used in human medicine.

Heparin is a widely used medication, including as a treatment for heart attack patients. It is also given to patients before and after certain surgeries to prevent blood clots.

Solomon said pigs free of alpha-gal sugar could make tissues available to people with alpha-gal syndrome for skin grafts, hernia repairs, heart valve replacements, or new tendons.

“It could be a source of other tissues or organs for  transplant,” Solomon said.

XenoTherapeutics of Boston is testing alpha-gal-safe pig skin from Revivicor, which makes the GalSafe pigs, in a first-in-human Phase 1 clinical trial for the treatment of burn wounds.

The FDA did consider whether the genetically altered pigs might worsen the problem of antimicrobial-resistant bacteria in humans or GalSafe pigs. The agency concluded that the microbial food safety risk is low, based on the low number of GalSafe pigs entering the food supply and ongoing surveillance for antimicrobial resistance, it said. The environmental impact of raising such pigs was also deemed minimal.

The FDA has previously approved genetic modifications to produce biologic drugs in animals: the first one, in 2009, was in goat milk, followed by one in chicken eggs and one in rabbit milk. Another approved genetic alteration  makes salmon grow faster. AquAdvantage salmon, made by AquaBounty, was approved in 2015 for food. 

Revivicor told the FDA it initially intends to sell meat from GalSafe pigs by mail order, not in supermarkets. The Virginia company has a famous lineage: In 2003, it was spun out from PPL Therapeutics, the U.K. company that along with the Roslin Institute in Edinburgh produced the first cloned animal, Dolly the Sheep.

Other companies, including eGenesis in Cambridge, Mass., and Qihan Bio in Hangzhou, China, are using CRISPR to create genome-edited pigs to provide organs free of viruses common in pigs but harmful to humans.

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