MEDICINE: Tobacco Plants Used As Basis For Cancer Vaccine

(previously published here at www.thebulletin.us)

By: Heather J. Chin, The Bulletin
07/24/2008

In spite of years of its name being associated with cancer, the tobacco plant has recently shown potential in the development of personalized vaccine cells to fight a specific type of non-Hodgkin's lymphoma.

Potential medicinal applications for tobacco are still in preliminary stages, but scientists at the Stanford University School of Medicine in California have published their current findings in the Proceedings of the National Academy of Science.

In their report, the researchers focused on creating antibodies for follicular B-cell lymphoma, which attacks the immune system and is currently considered incurable. A "B-cell" is a type of white blood cell responsible for defending the body against bacteria and other pathogens that cause illnesses.

After isolating the patient's cancer cells, the antibody-producing gene is extracted and transplanted to the "tobacco mosaic virus," which is then used to infect the tobacco plants. The infection then spreads through the cells and the gene produces large quantities of antibodies. After only a few days, the researchers ground up some of the leaves and extract the antibodies necessary.

Only a few plants are needed to produce enough vaccine for one patient.

In the first test of a plant-based vaccine on humans, 16 patients recently diagnosed with follicular B-cell lymphoma were injected with their individualized vaccines. More than 70 percent of the patients had an immune response and 47 percent had the specific response the researchers hoped for.

While the idea of producing and using individualized antibodies for patients is not new, as previous cancer vaccine trials have been done using animal and human cells, but those had mixed results. This early study using plant tissue has both speed and limited side effects on its side.

"This would be a way to treat cancer without side effects. The idea is to marshal the body's immune system to fight cancer," said Dr. Ronald Levy, senior author of the study. "We know that if you get the immune system revved up, it can attack and kill cancer."

Part of the appeal and benefit is in the speed and inexpensive production process. Each year, about 16,000 people are diagnosed with follicular B-cell lymphoma. Treatment is often limited to constant monitoring by doctors to see if a patient's condition worsens, with chemotherapy being avoided. With so few options, a vaccine would have a significant positive impact.

Since the study was only designed to test whether the plants were practical, safe and effective in stimulating a boosted immune system response, larger and more in-depth studies would need to be conducted to test how well such vaccines might perform in reducing the size of tumors.

The irony of using plants that produce tobacco - the main component in cigarettes, a known cancer-causing agent - as the base from which to develop a cancer-related vaccine was not lost on the researchers and everyone involved.

"It's pretty cool technology, and it's really ironic that you would make a treatment for cancer out of tobacco," said Dr. Levy. "That appealed to me."

The tobacco plants and research technology were provided by Large Scale Biology Corp., a company located in Vacaville, Calif., and the study was funded by the U.S. National Institutes of Health. Further studies into plant vaccines will be taken to major pharmaceutical company, Bayer, which has similar technology and greater financial resources to support the research.


Heather J. Chin can be reached at hchin@thebulletin.us


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