Researchers fight cervical cancer with tobacco plant
May 29th, 2006
Look again. That acre of tobacco might not be an acre of potential cigarettes. It might be an acre of cervical cancer vaccine. In the not-so-distant future, the plant linked to lung cancer — the leading cancer killer nationally — could be used to help prevent cervical cancer — the second-most-deadly cancer in women worldwide.
Step one: prevent cervical cancer
Researchers Alfred Bennett “Ben” Jenson, M.D. and Shin-je Ghim, Ph.D., at the University of Louisville James Graham Brown Cancer Center were part of the original team that invented the vaccine that neutralizes the human papilloma virus (HPV), the major cause of cervical cancer.
Their original work, completed at Georgetown University, is the basis of the world’s first preventative cancer vaccine. Pharmaceutical companies Merck and GlaxoSmithKline are developing it for market. Merck’s clinical trials made headlines in fall 2005 when the vaccine proved to be 100 percent effective in preventing HPV in the women tested. It is engineered to protect women against the two viruses that cause 75 percent of all cervical cancer cases.
Final FDA approval is expected by June, and although the company to first market the vaccine, Merck, has not released its price, speculation is that it will be expensive. While the cost probably would not be prohibitive for most American women to receive the vaccine, it could have implications for women in underdeveloped countries and underserved women in the United States.
Step two: access for all
With availability to all women foremost in their minds, now Jenson and Ghim are looking for a less expensive vaccine. One way to do that is to make the tobacco plant their factory.
“To work with a plant, or an acre or two of plants, requires primarily water and sun,” Jenson said. “To work with that much vaccine protein within a factory requires incubators, media to supplement the culture, carbon dioxide” — not to mention personnel, the building and everything it takes to keep that building running.
“The decision to use tobacco as the host was an easy one,” he said. “More is known about the tobacco plant genetically than any other plant, and it’s being used in a number of creative ways.“ There also is a need to provide alternate uses of the plant for southern farmers, many of whose families have been growing tobacco for generations.
Questions remain, though.
The original vaccine mimics the L1 protein of the papilloma virus and causes the body to develop antibodies to fight the virus. The second vaccine will use small fragments of the virus’ L2 protein that are grown in genetically modified tobacco plants.
“We hope that it will be an effective, much less costly vaccine,” he said.
Step three: find a cure
Once development is complete, however, Jenson and Ghim’s crusade against cervical cancer will continue.
“Cervical cancer is the most common sexually transmitted disease in humans,” Jenson said. “No one knows who’s infected, particularly the males,” who are the carriers.
While the original and subsequent vaccines will prevent cervical cancer, they only will be effective if a woman is not infected with HPV.
For Jenson and Ghim, the next step is clear: to create a therapeutic treatment to cure women who already have cervical cancer.