Fall of pioneer in using transgenic plants for pharmaceuticals has analysts worried field may dry up
By Ted Agres (firstname.lastname@example.org) | January 17, 2006
Large Scale Biology Corp., a pioneer in transgenic plant-based therapeutic proteins and vaccines, has become the latest casualty in the field of ?pharming,? or producing therapeutic proteins, antibodies, and vaccines from transgenic plants. After running out of funds in late December, the company dismissed all 78 staff members in Vacaville, Ca. and 23 employees from its commercial-scale biomanufacturing facility in Owensboro, Ky. ? and left analysts speculating about the future of the shrinking field.
?Pharmaceutical and biotech companies have enough risk taking a new drug through the approval process. To add to that an as-yet unproven plant-based technology is not something they are willing to do,? said Roger Wyse, managing director of Burrill and Co., a San Francisco-based life sciences venture capital firm. ?That?s adding risk on top of risk,? he told The Scientist.
In the 1990s, the concept of pharming held great appeal to drug and biotech companies, scientists, and investors alike, anticipating that plant-made proteins would be less expensive and potentially safer than those produced by traditional mammalian and bacterial cell culture methods. Large Scale alone spent millions of dollars developing therapeutic proteins, biologicals, and personalized cancer vaccines from transgenic tobacco and other crops.
But environmental opposition, regulatory uncertainties, and improvements in fermentation techniques have since dampened the industry?s enthusiasm. A decade ago more than 180 companies and organizations, including many of the big pharmas, were involved in pharming research. Since then, Pfizer, Eli Lilly, Novartis, and others have spun off or disposed of their agricultural-biotech drug divisions. Today, fewer than 75 companies worldwide -- and only a handful in the US -- are engaged in any form of plant-based therapeutics, said Lisa Dry, communications director for the Biotechnology Industry Organization (BIO) trade association in Washington DC.
Robert Erwin, a company founder and chairman, said the major problem Large Scale faced was reluctance from drug companies to having their products developed in crops to cut costs, without knowing how the Food and Drug Administration would view any resulting new drug applications. "We really miscalculated on the motivations that a pharmaceutical company would have to reduce the cost of manufacturing biotech products," Erwin told The Scientist. "Right now there's not much incentive for large pharmaceutical companies to worry about either prices or cost because they can price products however they choose."
Additionally, advances in fermentation technologies have all but eliminated projected cost savings between using plants and cell culture approaches, said Charles Arntzen, director of the Center for Infectious Diseases and Vaccinology at Arizona State University?s Biodesign Institute in Tempe, and a veteran researcher in the field. But even if the cost differentials had remained, the pharmaceutical companies wouldn?t have cared. ?For high-value pharmaceuticals, like a new cancer drug, the cost of goods is trivial compared to what they can sell it for,? Arntzen told The Scientist.
Nevertheless, several companies are continuing to develop plant-based drugs and vaccines. While none has been brought to market in the US, several are in Phase I and II clinical trials. These include recombinant alpha interferon and monoclonal antibodies developed from duckweed by Biolex Therapeutics in Pittsboro, NC, and secretory IgA (SigA) monoclonal antibodies to prevent tooth decay developed from tobacco by Planet Biotechnology in Hayward, CA. Unlike other monoclonal antibodies, SigA can be produced only in transgenic plants, the company claims. "There will be niche opportunities where plants have a special capability for creating unique materials," Arntzen said.
University of Central Florida researchers recently developed a vaccine against anthrax (Bacillus anthracis) using a recombinant tobacco chloroplast genome. In mice, the vaccine proved as potent against anthrax as fermentation-produced vaccine and was also free from the latter?s bacterial toxin that can cause harmful side effects.
Arntzen and his colleagues also recently developed a vaccine against plague (Yersinia pestis) using recombinant tobacco, producing high levels of plague antigens that protected guinea pigs against aerosolized plague. ?The plants find this protein totally innocuous and will crank out better levels than you can get in a bacterial fermentor,? Arntzen said.
By Ted Agres
Links within this article
Large Scale Biology
Charles Arntzen - ASU - Biodesign Institute
V Koya, etal, ?Plant-based vaccine: Mice immunized with chloroplast-derived anthrax protective antigen survive anthrax lethal toxin challenge,? Infection and Immunity, December 2005.
L Santi, etal, "Protection conferred by recombinant Yersinia pestis antigens produced by a rapid and highly scalable plant expression system," Proceedings of the National Academy, Jan. 12, 2006
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