Biopharming: Growing Medicine Crops
In biopharming, an emerging area of the biotechnology industry, plants are genetically modified to produce pharmaceuticals, also called plant-made pharmaceuticals (PMPs).
Typically, biologics such as antibodies and enzymes are manufactured using expensive mammalian cell cultures in bioreactor facilities. Today, there are four drug products (requiring human antibodies) that use an estimated 75% of the mammalian cell fermentation capacity. As new therapies are discovered, even more products will compete for these facilities, which take 5–7 years to build and cost about $600 million.
These drugs treat a variety of diseases and conditions such as arthritis, Alzheimer’s, diabetes, herpes, cancer, and infectious diseases. Currently, the demand for these drugs is greater than the supply or the ability to produce them fast enough. Biopharming may serve as an alternative to the traditional method of drug production, not only by providing the necessary supply of drugs to meet the demand, but also by significantly reducing the cost to produce them. Consequently, PMPs could provide more medications for patients at more-affordable prices.
At this time, no PMPs have been approved by the Food and Drug Adminstration, but clinical trials and field tests are in progress. Crops that have been recognized as good sources for pharmaceutical production include alfalfa, corn, potato, rice, safflower, soybeans, and tobacco. The considerable knowledge and experience with these crops with regard to genetics, agronomics, growth patterns, and environmental effects are reasons why many suggest their use. However, further testing is required to demonstrate that PMPs are safe and as effective as their traditional counterparts.
Serious concerns have been raised by the food industry, environmental groups, and consumer advocates as to how these crops would be contained. A policy of zero tolerance is being urged to prevent the accidental contamination of medicine crops into the food supply (for humans and livestock) or into the nearby environment. Some strategies include using nonfood crops, such as tobacco and grasses, engineering the plants so that the proteins are expressed in nonfood parts of the plant or sterilizing the plants, using visual markers to differentiate pharma crops from food crops, using atypical growing seasons, and growing genetically engineered crops in confined spaces such as greenhouses.
The U.S. Dept. of Agriculture’s Animal and Plant Health Inspection Service (APHIS), through its Biotechnology and Regulatory Services program, is the main agency responsible for monitoring field cultivation and approving field testing. USDA’s Center for Veterinary Biologics is also involved in the permitting process. FDA will regulate PMPs through several centers: the Center for Biologics, Evaluation and Research, Center for Drug Evaluation and Research, Center for Food Safety and Applied Nutrition, and Center for Veterinary Medicine.
The agencies are expected to use existing authorities for PMPs. However, this presents some interesting situations. For example, the pharma field would be equivalent to a drug production facility and would require adherence to regulations. These authorities also afford restrictions. For example, APHIS considers certain plants such as alfalfa and canola not suitable for biopharming because of specific characteristics of the plants, including multiple-year seed dormancy, sexual compatibility with other species in close proximity, and the fact that they are bee pollinated. In 2002, APHIS approved 20 field tests of plants used for making pharmaceuticals, which included barley, corn, rice, sugarcane, tobacco, and tobacco mosaic virus, on about 130 acres of land in nine states. Permits are issued on a case-by-case basis.
Permit requirements issued by APHIS for the 2003 growing season have been strengthened. Currently, APHIS is requiring a one-mile buffer zone around fields used for producing PMPs and demanding that equipment and facilities be specific for genetically modified crops. USDA will also ensure that personnel are trained and permit requirements are comprehended and implemented. Inspections will increase from an average of one visit per year to five per growing season and two the following year.
Biopharming may provide an opportunity to meet the demand for faster and less-expensive production of certain drugs and offer more-affordable medications to patients. Although biopharming may be beneficial in many regards, ensuring adequate confinement of these medicine crops from entering the food supply will be vital, not only to the food industry and other organizations, but also to preserve the public’s trust in America’s safe food supply.
by JENNIFER MACAULAY
IFT Staff Scientist
Office of Science, Communications, & Government Relations