In the bag. These cultured carrot cells are engineered to make a human drug.

MANY A CHILD HAS BEEN TOLD “CARROTS eign much as if it were one of the might be simpler to process because they are good for you.” That advice could soon take ’s own . would be free of animal . on new meaning for people with Gaucher dis- However, technological hurdles and a Other discoveries followed. In 1995, for ease, an inherited metabolic disorder that leads lack of interest from drug companies have instance, Arntzen’s group reported in to liver and bone problems. Patients must now hamstrung “pharming,” as have worries that that potatoes engineered to make a on April 12, 2009 be injected every 2 weeks with a manufactured pharma will escape from their experi- protein worked as a when the spuds enzyme that costs on average $200,000 a year, mental plots and taint the food supply. As a were fed to mice. Such “edible ” could making it one of the most expensive drugs ever. result, many companies have abandoned this offer developing countries cheap oral vaccines If ongoing clinical trials go well, the 5000 Gaucher research or gone under. And no plant- that didn’t require refrigeration, Arntzen sug- patients on the therapy could soon have a made drugs for humans have made it to gested (Science, 5 May 1995, p. 658). second option—a cheaper version of the the pharmacy. A company called Large Scale enzyme that stays in the bloodstream longer But academic scientists and some compa- Corp. in Vacaville, California, came up with a and can be injected less often. nies have persisted, improving yields of shortcut. It didn’t bother to create a new

If the U.S. Food and Drug Administration plant-made drugs and developing innovative strain when it wanted to produce an www.sciencemag.org (FDA) approves recombinant glucocerebrosi- ways to keep pharming inside the lab, or the antigen for a lymphoma vaccine. It simply dase, it will be good news not only for medicine greenhouse. Several plant-made pharmaceu- sprayed tobacco with a tobacco mosaic but also for a community far removed from the ticals (PMPs) are now in patient trials (see virus carrying the appropriate . The clinic: plant scientists. Protalix Biotherapeutics chart, p. 474). Moreover, the European leaves produced useful amounts of the vaccine in Karmiel, Israel, produces this new version of Union, the Bill and Melinda Gates Founda- protein within 14 days. The drug worked in the protein in giant plastic bags, not in steel vats tion, and the U.S. Department of Defense are mice, suggesting that vaccines tailored to lym- of mammalian cells like most biologics are. fertilizing the field with new funding. “We’re phoma patients’ tumors could be made in Downloaded from The bags are filled with transgenic carrot cells actually not doing too bad,” says Julian Ma, plants in just weeks. And because the plants that are cultured and then processed to extract an immunologist at St. George’s University carried the foreign gene only until they shed the drug. “If Protalix gets regulatory approval, of London in the U.K. “It’s just that everyone their leaves, they were potentially more that would [make it] the first plant-made phar- is in a hurry.” acceptable than permanently modified crops. maceutical,” says plant scientist Charles Arntzen of Arizona State University in Tempe. Fields of dreams “For people who work in this field, it will be a The excitement over plant-made very exciting step forward.” pharmaceuticals began with a Arntzen is chasing an elusive dream: using 1989 paper in Nature showing whole plants as factories to make drugs. that monoclonal could Nearly 20 years ago, when researchers first be produced in tobacco. The paper showed that a tobacco plant could be engi- “really captured the imagination,” neered to crank out an , they envi- says Ma. Monoclonal antibodies sioned harvesting cheap supplies of therapeu- were being used to treat a growing tic , antibodies, and vaccines from vast number of , from arthritis fields of crops. For this approach, researchers to cancer, but were expensive to isolate the target gene and usually insert it into make in mammalian cells. So- a bacterium called that readily called plantibodies appeared to Temporary transgenic. Fluorescing protein shows infects the plants and passes on the gene. The offer a cheaper production tobacco leaf’s pharming gene becomes part of the plant and is passed method—a kilogram might cost potential.

CREDITS (TOP TO BOTTOM): PROTALIX; AG BAYER CREDITS (TOP TO BOTTOM): PROTALIX; from one generation to the next, producing for- $100 rather than $3 million—and

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Safety in Washington, D.C., says Selected Plant-Made Pharmaceuticals enforcement is “horrendous.” As a result, “we don’t think [drugs] should Company Plant Grown in Drug or product Status be in any food crops, indoors or out- doors,” he adds. Many ecologists and Human drugs some plant scientists are also leery of Protalix Biotherapeutics carrot glucocerebrosidase Gaucher disease Phase III trial* using food crops for pharma. “It’s too Therapeutics duckweed indoor chambers alpha Phase II trial* dangerous,” says Kenneth Palmer, SemBioSys field diabetes Phase I/II trial † former director of the vaccine pro- Meristem Therapeutics corn field Phase III trial † gram at Large Scale Biology. These concerns drove many com- Other products panies away from using food crops field , diarrhea Efficacy trial § such as corn for pharmaceuticals. A Cobento Arabidopsis greenhouse human intrinsic factor Vitamin B-12 deficiency Approved †† few big companies, such as , dropped PMP research altogether. Planet tobacco field secretory antibody vaccine E.U. approved Stung by bad press and lack of interest Dow AgroSciences tobacco cell culture poultry vaccine Newcastle disease USDA approved from drug companies, many leading CIGB, Cuba tobacco greenhouse vaccine purification antibody On market plant pharma companies have folded, * Ongoing; † Projected late 2008; § Completed; †† In Ukraine. including ProdiGene and Large Scale Steps along the way. No plant-made human drug has made it through final clinical trials, but several “pharmed” Biology. As Palmer puts it, “the proteins are close to or on the market as supplements, a vaccine reagent, and a medical device. field imploded.” on April 12, 2009 Scores of biotech companies sprang up to make a pig vaccine sprouted in a soybean field Close to the clinic commercialize these discoveries, and some in Nebraska. For this and an Iowa mishap, the Despite the setbacks, a handful of companies in big agbiotech companies got involved as U.S. Department of (USDA) the United States and Europe haven’t given up. well. By the mid-1990s, more than 180 com- fined the company $250,000 and made it pay A few have plowed ahead with food crops, panies and organizations were working on $3 million to buy and destroy tainted soy- grown outdoors, for their pharma products; pharming, according to the Biotechnology beans. The incident stoked opposition from others have focused on other plants or on Industry Organization. farmers and activists worried about “drugs in unconventional growing schemes. The companies soon ran into technological your cornflakes.” Meristem Therapeutics in Clermont-

snags, however. Biotechnologists couldn’t Other companies underestimated the pub- Ferrand, France, plans to start final clinical www.sciencemag.org always get plants to express enough protein and lic’s concerns. A company called Ventria Bio- trials for a corn-grown gastric lipase for cystic had trouble purifying the protein product. science that wanted to conduct field trials of fibrosis patients by the end of the year. And the Efforts to make stalled after rice containing two breast-milk proteins useful Canadian company SemBioSys Genetics Inc. researchers realized that the amount of antigen in combating diarrhea drew the ire of rice uses transgenic safflower—“much less of a fluctuated widely from plant to plant. Arntzen growers in California, then Missouri. It wound lightning rod than some other crops,” says CEO thinks that oral vaccines made from dried plant up in Kansas, where no other rice is grown. Andrew Baum—to produce insulin, which material could work for developing countries, USDA tightened its rules for field trials of should be in clinical trials this year. Companies Downloaded from but a vaccine without a strictly controlled dose pharma plants in 2003 to prevent mistakes like such as Protalix and Biolex Therapeutics side- “would never be approved” in the United the ProdiGene episode. But skeptics were not step the growing of crops altogether: the former States, he says. assuaged. Bill Freese of the Center for Food with its carrot-cell culture to make a Gaucher Another reality check: lukewarm interest disease enzyme, and the latter by producing from the big drug companies. They didn’t interferon using duckweed, tiny clonal plants much care that plant-made drugs would be grown as a layer in clear plastic bags. “We are (SOURCE) INDIVIDUAL COMPANIES AND MOLECULARFARMING.COM; SEMBIOSYS AND MOLECULARFARMING.COM; (SOURCE) INDIVIDUAL COMPANIES cheaper to make because production is a careful not to be associated with whole-plant small chunk of the cost of drug development; transgenic technology,” says Protalix CEO the big-ticket item is clinical trials. The com- David Aviezer. SCIENCE panies were also leery of the regulatory hur- New technologies are attracting attention. dles, because both the drug and the new pro- To boost expression, the German biotech Icon duction process would have to clear FDA. Genetics relies on to get - “Most pharmaceutical companies aren’t will- laden viruses into tobacco plants. The company ing to take a chance on a drug produced in dips the plants into a solution of Agrobacterium plants,” says Roger Beachy, president of the that carries the DNA for a deconstructed Donald Danforth Plant Science Center in , which in turn contains St. Louis, Missouri. the gene for the desired drug. The bacterial Flower power. This Also, like other genetically modified crops transgenic safflower bath, followed by a few seconds in a vacuum, (see pp. 468, 472), pharma plants can be a makes seeds containing gets far more of the virus into plant-leaf public relations nightmare. In 2002, leftover insulin. than conventional spraying.

corn plants engineered by ProdiGene Inc. to In a 2006 paper in the Proceedings of the CREDITS (TOP TO BOTTOM): (GRAPHICS)N. KEVITIYAGALA/

474 25 APRIL 2008 VOL 320 SCIENCE www.sciencemag.org Published by AAAS National Academy of Sciences (PNAS), they reported that this method, combined with other techniques, increases the amount of antibody by up to 100-fold, reducing the size of the needed and making it feasible to grow plants commercially indoors. Com- pared with making a transgenic plant, which takes a year or two to develop, this “magnifection” can go from gene to grams of protein in a couple of weeks. “It’s incred- ibly promising technology,” says Ma, who, like other academic researchers, is trying out magnifection. With help from the drug giant Bayer, which bought the company in 2006, Icon Genetics will open a clinical-grade manufac- AMONG WINE CONNOISSEURS, OPINIONS Udine, Italy, the two grape genome groups turing plant in June. It expects to begin trials differ about whether 2007 will prove a good began to put aside their rivalry. “I’m hopeful with a cancer vaccine tailored to individual year for Pinot Noir. But among plant geneti- there will be more collaboration now,” says patients in 2009, says CEO Yuri Gleba. cists, it’s the finest vintage ever: Last year, two Vigna/Vigne member David Horner of the Bayer’s move is a healthy sign of regrowth European teams published high-quality drafts University of Milan in Italy. “It’s cool there for the pharming field, Ma and others say. And of two Pinot Noir–derived genomes. are two cultivars done. It allows more com- other new sources of support are helping too. Plant are toasting the genomic parative work.” on April 12, 2009 Last month, Pharma-Planta, a €12 million, double-header. This is the first fleshy fruit and A key motivation for deciphering the grape 5-year, European Union–funded project just the fourth flowering plant to have its genome is to prevent a repeat of the eco- co-coordinated by Ma, described in PNAS an genome decoded. And in nomic devastation that anti-HIV microbicide grown in corn or economic terms, grapes struck the European tobacco that could be ready for testing next top the world’s fruit crops: wine industry in the late year. The Defense Department and other U.S. We consume them fresh 1800s. At that time, government agencies have provided the or dried, crush them into phylloxera, sap-sucking Fraunhofer USA Center for Molecular juice, and use them to insects from North

Biotechnology in Newark, Delaware, nearly make wine that can sell America, ravaged Euro- www.sciencemag.org $14 million to use a technique like magnifec- for many thousands of pean grapevines. Today, tion to make vaccines. It has tested dollars a bottle. “The winemakers and grape and plague vaccines in nonhuman primates contributions of these researchers are strug- and a pandemic flu vaccine in ferrets. “[We] sequencing efforts are gling to combat new can do things much faster than any other tech- enormous and historical,” threats, particularly nology,” says Executive Director Vidadi Yusi- says grape researcher downy and powdery mil- bov, slashing in half the 6 months it now takes Steven Lund of the Uni- dew, diseases that have Downloaded from to make flu vaccine the traditional way, in versity of British Colum- made their way to Europe chicken eggs. The organization also has bia in Vancouver, Canada. from the United States $8 million from the Gates Foundation for The story behind the over the past century. plant-based vaccines for malaria, sleeping grape genome is one in Wine woes. Powdery mildew (above) and These fungi are an envi- sickness, and flu. which a worldwide sci- other fungal diseases can devastate vineyards. ronmental as well as an As visions of endless fields of pharma entific community came economic nightmare: crops have faded, so have unrealistic expecta- together, then partially splintered into rival Although only about 5% of Europe’s farmland tions for pharming. Scientists say they now camps; money to support sequencing was is dedicated to wine vineyards, they account for realize that they need to be smarter about the hard to come by; and success has brought both about 70% of the region’s fungicide use. marketability of the drugs they develop in new insights and delicious questions. The The new genome information should plants. They think the best bets—Protalix rivalry provided the drama of the story. For a speed the creation of hardier vines, which has aside—may be high-volume biologics, such while, a French-Italian grape genome been slow going. “The target now is clearly as microbicides, monoclonal antibodies, and alliance called Vigna/Vigne looked like it was resistance genes,” says Vigna/Vigne member vaccines, particularly for use in developing going to be beaten by a disgruntled researcher Michele Morgante from the Institute of countries. Getting these first low-hanging who started his own genome effort. Genomic Applications (IGA) in Udine. New fruits through clinical trials and FDA approval “Undoubtedly, competition was a driver here, insights into the locations of these genes can should allay concerns about safety and envi- perhaps in a microcosm of the human genome assist breeders as they try to develop better ronmental risks. Says Palmer, now at the Uni- sequence drama of years past,” says Lund, varieties, for example. And identifying genes versity of Louisville in Kentucky, “Once two referring to the bitter contest between public in the few grapes that are resistant to drought or three products [win approval], the field and private programs to decipher our genetic * * CREDITS (TOP TO BOTTOM): CHARLES O'REAR/CORBIS; HOLT STUDIOS INTERNATIONAL LTD / ALAMY LTD STUDIOS INTERNATIONAL CREDITS (TOP TO BOTTOM): CHARLES O'REAR/CORBIS; HOLT should really take off.” –JOCELYN KAISER code. Recently, however, at a workshop in Tuning the Taste of Wine, 7 March 2008, Udine, Italy.

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