Aug. 28, 2000 Strong evidence of effectiveness in animal tests
Washington D.C., August 22 -- Today, mothers urge vitamin D on their children to build strong bones and teeth. Within a decade, a chemically modified version of the vitamin could become one of a small but growing number of drugs used to prevent cancer, researchers reported today at the 220th national meeting of the American Chemical Society, the world's largest scientific society.
Vitamin D is often added to milk and produced naturally by skin exposed to sunlight. But taken in the amounts needed to realize its cancer prevention potential, vitamin D can be too much of a good thing. Prolonged use can lead to osteoporosis or even death.
Now, a research team at Johns Hopkins University in Baltimore, Md., with funding from the National Institutes of Health, says that it may have found a way around the problem. The researchers designed four different versions of vitamin D in their laboratory and tested them on two groups of mice: one that was painted with a tumor-inducing chemical and one that was not. Then they compared how the two groups fared.
After a 20-week treatment period, the most promising vitamin D candidate reduced the incidence of tumors by 28 percent and the number of tumors by 63 percent. The results demonstrate the drug's potential effectiveness in preventing cancer, according to the researchers. Previous studies in mice have shown that the drug is safe when ingested, they say.
"This is among the very best vitamin D analogs in terms of its therapeutic profile," says Gary H. Posner, Ph.D., principal investigator of the study and a professor of chemistry at the university. He is collaborating in this effort with Thomas W. Kensler, Ph.D., a professor at the university's School of Hygiene and Public Health.
Posner cautions that the drug, which has not yet been tested in humans, is still in the early stages of development and could take 10 years to hit the market. If successful, the drug will most likely be given to patients at high risk for cancer, he says.
There has been a growing interest in cancer prevention, with many studies claiming the cancer-preventive properties of teas, herbal medicines and vitamin supplements, including vitamins A, C and E. Many of these claims are untested or poorly tested, while the compounds themselves are generally not regulated. As a result, consumers who use these products are subjecting themselves to potential health risks, says Posner.
Other laboratories are also developing cancer-preventive drugs, but none has yet made it to the market, he says. Celecoxib, a drug approved for the treatment of arthritis, is now being evaluated by the NIH for the prevention of colon cancer. Oltipraz, developed to treat a type of parasitic worm infection, is undergoing human trials for the prevention of liver cancer.
This year, more than 550,000 Americans are expected to die of cancer and more than one million new cases will be diagnosed, according to the American Cancer Society. The disease is the second leading cause of death in this country, behind heart disease. Development and production of any drug that is scientifically proven to prevent cancer in humans would be a historical milestone, says Posner.
The paper on this research, MEDI 191, will be presented at 12:45 p.m., Tuesday, Aug. 22, in the Washington Convention Center, Room 30.
Gary H. Posner, Ph.D., is a professor of chemistry at the Johns Hopkins University in Baltimore, Md.
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