Tobacco plants may be used to make a personalized cancer vaccine for patients with a chronic form of lymphoma, according to a study released Monday.

The treatment, which would marshal cancer patients' own immune response to fight their own tumor cells, is made using a new approach that turns genetically engineered tobacco plants into personalized vaccine factories.

"This is the first time a plant has been used for making a protein to inject into a person," said Dr. Ron Levy of Stanford University School of Medicine in California, whose research appears in the journal Proceedings of the National Academy of Sciences.

"This would be a way to treat cancer without side effects," said Levy.

Levy's team tested the vaccine on 16 patients who were recently diagnosed with follicular B-cell lymphoma, a chronic, incurable disease.

None of the patients experienced any significant side-effects and more than 70 percent of the patients developed an immune response, the study found.

While they have not yet determined whether the immune response is sufficient to destroy the cancer, the researchers are hopeful that the technique could one day lead to a cure for at least some types of the deadly disease.

"Every lymphoma patient has a target on their tumor cells but each patient's tumor has a different version of that target," Levy said in an interview.

Finding the right target requires cloning the genes from the patient's tumor.

Researchers scratch tobacco leaves with the gene-laced virus to infect the plant, which subsequently produces the protein antibodies also seen in the patient's tumor. The leaves are plucked a few days later and ground into a green pulp, from which the antibodies are extracted and purified. They are then injected back into the patient, Levy said.

"This technology is special because it's fast and very suitable to this customized, personalized approach because each plant can be making a different person's (vaccine)," Levy told AFP.

This is the first time a plant-based cancer vaccine has been tested on humans.

The plant-based vaccine has a number of advantages. It can be developed much more quickly and at far less expense. It does not carry the risk of infection should the animal cells be contaminated. And the antibodies produced may also spark a stronger immune response than those developed in mammalian cells.

(Agencies via Xinhua News Agency July 22,2008)