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Model Pigs Face Messy Path

Amy Maxmen wrote for Nature about the challenges being faced by animal biotechnologies, focusing on Exemplar’s genetically engineered pigs.
 
As the United States’ first genetically engineered (GE) pigs with muscular dystrophy, the Exemplar pigs could be used to test treatments for the disease. But their utility will remain limited for the time being, while the U.S. Food and Drug Administration (FDA) works out how to regulate them.
 
Exemplar Genetics aims to sell GE pig models for use in academic and pharmaceutical laboratories. Some pigs have cystic fibrosis, others with heart disease, arrhythmia or cancer, and now muscular dystrophy. Because pigs mimic these human diseases more closely than mice, they are desirable models for drug testing and for studying the disease process.
 
However, as the first company to seek approval for a disease model in a GE animal that could, in theory, also be eaten, Exemplar is navigating a dimly lit regulatory path. In 2009, the company submitted its first application to the FDA for approval of its cystic fibrosis pig model. “We don’t really know what additional steps we need to do in order to get FDA approval for full commercialization,” says John Swart, president of Exemplar. Nevertheless, the company remains hopeful that its pigs will skirt the hardships that have befallen other GE animals in the pipeline.
 
As early as 1999, the FDA spoke about the promise of GE animals for both food and pharmaceutical purposes. Ten years later, the agency created a framework to judge their safety. In 2009, it applied the guidelines in approving a GE goat that produces a blood-clotting drug in its milk.
 
 
Since then, however, FDA approvals for two GE food animals have stalled: a salmon with a gene prompting faster growth, and a hog engineered to excrete less-toxic manure. Members of Congress have voiced their fears about such ‘frankenfish’, and environmental groups are concerned that transgenic animals might escape and interbreed with wild populations.
 
“GE pigs for medical models could move more quickly because there’s a strong need for them in the medical community,” suggests David Edwards, director of animal biotechnology at the Biotechnology Industry Organization based in Washington, D.C. Although animal-rights advocates may object to disease-model pigs, Swart predicts that they will avoid intense public scrutiny because they aren’t meant to be eaten.


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