Pharming Sheep and Corn
April 3, 2003
Although neither cloning nor genetic modification of commercial farm animals has fulfilled its early promise, a handful of firms are still pursuing a different take on farming. They are designing animals (and also crop plants) as factories for making therapeutic proteins.
GTC Biotherapeutics, of Framingham, Mass., is using livestock to make its drugs, while Epicyte, based in San Diego, hopes to pull off a similar trick with corn.
GTC's technique is to get its animals to secrete the desired protein into their milk.
- GTC now has 15 varieties of engineered goat and is branching out into cows, which have a bigger yield of milk and therefore protein.
- The company has high hopes for a substance called AT-3, an anti-clotting agent used in coronary-bypass operations and to prevent deep-vein thrombosis in susceptible individuals.
- A non-caprine version is already approved for use in Europe and Japan, where the combined market is worth $250 million a year.
Epicyte's researchers have modified maize plants to make therapeutic antibodies and express them in large quantities in the endosperms of their seeds.
- Other products in the works include antibodies against herpes and respiratory syncytial virus, which causes dangerous lung infections in children.
- In addition, the firm is developing an antibody to one of the proteins involved in Alzheimer's disease.
Besides turning out drugs cheaply (at $1 to $2 a gram, compared with around $150 a gram from a bioreactor), both of these technologies are easy and inexpensive to scale up.
A traditional protein-drug factory costs $200 million to 400 million and takes between three and five years to build. A new strain of goats costs $100 million to develop and takes only 18 months. And if more capacity is needed, growers can expand quickly by simply breeding more animals or planting more fields.
Source: "Pharming Today: A Novel Way to Make Drugs," Economist, April 4, 2003.
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