Using Tobacco to Fight Cancer

Author: Vickie Richter

For years tobacco has been labeled as a smoking gun—it's the leading cause of preventable deaths in the United States, killing approximately 438,000 people per year, including 38,000 deaths from exposure to secondhand smoke. Now, ironically, a personalized vaccine tailored to a patient's specific tumor type, has been developed using the leaves of the tobacco plant. The vaccine is being tested on patients with follicular (non-Hodgkin) lymphoma, a chronic incurable disease, which affects mainly older adults.

Professor Ronald Levy and team, of Stanford University School of Medicine, tested the vaccine on 16 patients who were recently diagnosed with follicular B-cell lymphoma, an immune-system malignancy diagnosed in about 16,000 people each year. The vaccine is developed by isolating the antibody gene from the patient's own tumor, then infecting the tobacco plant with the gene-carrying virus by scratching the virus onto the leaves. Once the gene is in the plant cells, it is able to produce a large quantity of antibodies, resulting in the need for only a few plants to make enough vaccine for each patient. With in a week's time the leaves are harvested and ground into a pulp, then the antibodies are extracted and injected into the patient. The cancer makes a specific antibody that is not found in healthy cells; therefore the strategy is that once the cancer-specific antibody is injected into the lymphoma patient, their immune system will be stimulated to destroy any malignant cells.

Although, follicular lymphoma often goes undiagnosed due to minor symptoms such as enlargement of lymph nodes, fever, weight loss, sweating and fatigue—once diagnosed, many patients will still choose watchful waiting in the early stages of the illness to avoid severe side effects of the standard chemotherapy treatment. The point of the study was to see if the plant-grown vaccine could allow earlier, more aggressive management of the cancer without such harsh side effects. More than 70 percent of the patients developed an immune response and 47 percent had a "specific" immune response, while none reported any side effects.

The researchers wanted to see if plants could produce a vaccine tailored to each patient's follicular lymphoma that was quick and inexpensive. Dr. Levy said, "This is the first time a plant has been used for making a protein to inject into a person." While this study only focused on the safety and immune-stimulating ability of the plant vaccines, more studies will be needed to show how effective they are as a treatment.

Personalized vaccines have also been grown in animal cells, but it takes months to produce the vaccine and cost thousands of dollars per patient. Plant generated vaccines do not carry the risk of infection should animal cells be contaminated and many ethical questions would be eliminated.

The study was funded by a grant from the National Institutes of Health and by Large Scale Biology Corp. and the findings are published in the Proceedings of the National Academy of Sciences.