In February 2009, farm animals became living pharmaceutical factories when the FDA approved a drugs produced by goats that had a human gene spliced into their DNA.
A company called GTC Biotherapeutics developed a way to insert a human gene sequence that produces the blood protein “antithrombin” into a short strand of goat DNA that normally controls milk production. The altered DNA was injected into the nucleus of a fertilized goat egg and then implanted into a female. When the goat kids were born, they were tested for the presence of the blood protein. Those that had the protein were bred normally to create a herd of modified goats. Eventually, the company had a herd of 200 bioengineered goats. Their milk is filtered and purified, and the antithrombin is extracted.
Antithrombin is used to treat a rare human blood disease that can cause fatal blood clots during surgery or childbirth. About one in 5,000 Americans has the hereditary disorder.
Before this method of production was approved, the drug was extracted from donated human blood or grown in large steel vats of genetically engineered cells. The new company says that their 200 goats produce as much of the drug as 90,000 human blood donations. In other words, goats can produce more of the drug than previous methods at a lower cost.
Some critics are concerned with using living organisms to produce drugs. They say that the animals could be harmed by the GMO techniques. Or they suggest that humans could be harmed if animal germs contaminate the drug, or if the milk or meat from the genetically altered animals gets into the human food supply. Some are concerned that the animals might escape and breed with normal goats, spreading the gene with unpredictable results.
The company is concerned that a disease could wipe out the herd. So, GTC fully vaccinates the goats. Access to them by people is controlled and there is a double fence around the farm to keep out wildlife and keep the goats in. And the company asserts that none of the goats in the herd, including normal goats used to breed the transgenic ones, will be allowed in the food supply.
Drugs have been derived from animals before, but this is the first drug approved from a herd of genetically engineered animals created specifically to serve as living pharmaceutical factories.
The development also represents another major step in human reliance on animals.
- Until Genentech introduced human genes that produce insulin into strains of bacteria, most of the insulin used by people with diabetes came from pigs or cows.
- Genetically engineered mice are now used to produce some drug ingredients.
- In the future, GTC is hoping to get approval for their goats to produce a new version of Rituxan, a cancer and arthritis drug now produced by Biogen Idec and Genentech.
- Researchers have created milk from genetically altered sheep and pigs that can treat a rare type of hemophilia.
- Another strain of altered pigs secretes milk with a hormone to help anemia patients produce more red blood cells.
- Many of the newer protein-based drugs, like the cancer drug Avastin and the arthritis drug Enbrel, are produced in genetically engineered Chinese hamster ovary cells that are grown in huge stainless steel vats. Living animals are cheaper.
Plants. In addition animals, some companies are genetically altering plants to produce drugs. In December 2009, the drug giant Pfizer bought rights to a drug developed by a small Israeli company, Protalix Biotherapeutics. Protalix had developed a way to produce a drug called “Cerezyme” by growing genetically modified carrot cells in large plastic bags. Before this technique, Cerezyme was produced by GM Chinese hamster ovary cells grown in stainless steel vats. Researching and setting up these cell culture factories can cost hundreds of thousands of dollars. The carrot method – and some animal methods – can cut the cost to tens of thousands of dollars, according to the companies involved.
Business analysts suggest that “pharm” animals and plants may be more profitable than traditional farming. The disease that Cerezyme is designed to fight is very rare. In 2009, only about 5,700 people in the world were being treated with the drug. But since it costs about $200,000 a patient each year, sales exceeded $1 billion in 2008.