July 21 (Bloomberg) -- Tobacco plants can produce a therapy for patients with a chronic form of lymphoma, according to the first human study of the approach.

Researchers at Stanford University and Large Scale Biology Corp. coaxed the plants into making antibodies of the type found on the tumors of individual patients by infecting their leaves with a virus laced with a gene from the cancer. The investigators say the approach led to personalized vaccines that may spark the patients' immune systems to attack the cancer.

Each year, about 16,000 people are diagnosed with the cancer, called follicular B-cell lymphoma. Doctors initially monitor the patients to see if their cancer worsens, rather than treat them with toxic chemotherapy. The plant-based vaccines may offer safer therapies that can be used sooner, said Ronald Levy, head of oncology at Stanford, in California. Levy was the lead researcher of the study, released today by the Proceedings of the National Academy of Sciences.

``This is a vaccine which is custom made for each person, because each person's tumor is different,'' Levy said in a telephone interview. ``For something like this where we need a different product for every person and we needed it fast, this is a very nice technology. The irony is that this is a treatment for cancer we're building out of tobacco.''

The study, in 16 newly diagnosed patients, was too small to determine if the vaccine helped, Levy said. It did show the approach is safe and generated the intended immune response. A second, larger study is needed to confirm the benefits, he said.

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.

No Contamination

``The immune system has had a chance to see this target already and isn't doing a good enough job,'' he said. ``We know that if you get it to change its form and look more foreign, you can get the immune system to wake up. In this case, we make the protein in a plant, which has its own way of folding the protein and putting its own sugars on it.''

The result is a safe, uncontaminated therapy that is personalized for each individual patient, he said. In addition, the tobacco plant grows quickly, an added benefit, he said.

The U.S. National Institutes of Health funded the study. Large Scale Biology Corp., based in Vacaville, California, provided the tobacco plants and technology.

To contact the reporter on this story: Michelle Fay Cortez in Minneapolis at mcortez@bloomberg.net

Last Updated: July 21, 2008 18:14 EDT