CTT™ in combination with tobacco as the host creates a production system with significant commercial advantages for production of plant-made-pharmaceutical proteins. The CTT™ tobacco advantage includes:

• Ease of generation of transplastomic plants;
• Greenhouse-confined seed production (a single tobacco plant can produce up to 1 million seeds);
• Generation to generation stability;
• Greatest yield of tobacco biomass/acre compared with other crop plants;
• Low risk of gene flow in the environment via pollen (tobacco self-pollination, chloroplast genome inherited via seed not pollen, seed produced in confinement);
• Non-food and non-feed crop;
• Development time competitive with current cell-based systems;
• Ability to express high levels of protein per unit of biomass.

Neutral regulatory/public acceptance risk

In the case of plant-made therapeutic products, there is uncertainty about the level of regulatory risk since a plant-made therapeutic has yet to be commercialized. The review process, however, will follow the existing regulatory framework developed for approval of biopharmaceuticals, and separately, genetically engineered plants. The FDA and USDA issued a joint draft guidance document in September 2002, providing an interpretation of the regulations and outlining points to address when requesting approval of "Drugs, Biologics, and Medical Devices Derived from Bioengineered Plants for Use in Humans and Animals"

      Confinement is a key concern in the regulation and public acceptance of genetically modified crops, particularly those expressing pharmaceuticals and industrial proteins in crops that primarily are used for food or feed. Even though these transformed individual plants are not intended for food or feed, the concern is that the gene or tissue expressing the protein will escape during field production through pollen movement, seed dispersal or growth of volunteers in subsequent growing seasons and inadvertently become commingled with food and feed crops. In a chloroplast system, the confinement risks are minimized by multiple inherent properties of the technology and process:

• Tobacco chloroplasts are maternally inherited, thereby removing the risk of gene transfer via pollen.
• Because leaves are used for processing, the risk of seed dispersal during harvest and transport is eliminated.
• Tobacco can produce up to 1 million seeds per plant, so all seed production can be completed in enclosed greenhouses, which further eliminates the risk of pollen movement.
• With regard to contamination of food or feed, tobacco is not grown for human food or animal feed, so it is unlikely that commingling would occur.
• Physical isolation from tobacco grown for smoking is easily achieved because tobacco is not widely grown.
• With our high yielding tobacco system, commercial quantities of protein can be produced from small acreage, which translates to lower overall environmental exposure/impact.

      These inherent properties of the Chlorogen process indicate low risk relative to USDA regulations and public acceptance.

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