GTC Biotherapeutics got the Food and Drug Administration to approve its anti-blood clotting drug, Atryn.
The drug is derived from the milk produced by its herd of 200 genetically engineered goats. As the International Herald Tribune explains:
To make its protein, GTC took the human gene for antithrombin and linked it to goat DNA that normally controls production of a protein found in milk. That insured that the antithrombin would be produced only in the milk.
The gene was injected into a one-celled goat embryo, which was then implanted into the womb of a surrogate mother. If it were doing it today, GTC would implant the gene into a skin cell of a desired animal and then produce a clone, a more reliable technique. But Dolly the sheep, the first cloned mammal, had not been created when GTC started its work in the early 1990s.
Once GTC had produced a goat with the human gene that produced the antithrombin in its milk, that "founder" animal was mated with others through conventional breeding to start producing a herd.
Why use goats and other animals to make therapeutic proteins?
Many of the newer protein-based drugs, such as the cancer drugs Avastin and Erbitux and the arthritis drugs Enbrel and Humira, are produced in genetically engineered Chinese hamster ovary cells that are grown in big stainless-steel vats.
But a cell culture factory can cost hundreds of millions of dollars to build. Using livestock eliminates all that steel and shrinks the investment to tens of millions of dollars, said Geoffrey Cox, chief executive of GTC.
One drawback is that given the generation and gestation times of animals, it can take 18 months to start getting protein production from a goat, compared with a few months for cell culture.
Of course, not everyone is happy that goats are exploited in this manner:
"It is a mechanistic use of animals that seems to perpetuate the notion of their being merely tools for human use rather than sentient creatures," the Humane Society of the United States says in its position paper on the practice.
Whole IHT article here.