Heartburn Medicines May Help Fight Cancer
In a lab, they lowered resistance to chemotherapy drugs
TUESDAY, Nov. 16, 2004 (HealthDayNews) -- Can common heartburn medications boost the effectiveness of chemotherapy drugs?
A new study by Italian researchers suggests that may be the case -- at least with laboratory animals. But, the scientists acknowledge, much more research is needed to prove whether proton pump inhibitors would be effective additions to cancer-fighting arsenals.
Still, the researchers suggest that doctors and drug companies should take into account how "pre-treating" tumors with proton pump inhibitors might boost the effectiveness of certain cancer treatments.
The study appears in the Nov. 17 issue of the Journal of the National Cancer Institute.
Resistance to chemotherapy drugs such as cisplatin and 5-fluorouracil is a major cause of treatment failure in cancer patients, the researchers said. Experts suspect the increased acidity in the cellular environment surrounding tumors is one reason for the failure. So, heartburn medications, which work by blocking the enzyme that produces acid, might help solve the problem, the Italian scientists said.
"One of the major mechanisms that prevents the cytotoxic drugs from killing the tumor cells is the tumor acidity," said Dr. Stefano Fais, senior investigator in the department of drug research and evaluation at the Istituto Superiore di Sanita in Rome, and corresponding author of the study.
To test the hypothesis that common heartburn medications might alter the cellular environment enough to boost the effect of the cancer drugs, Fais and his colleagues used tumor cell lines derived from human cancers such as melanomas and lymphomas -- cancers of the lymph system.
They pre-treated the cell lines with heartburn medications, including omeprazole (Prilosec), esomeprazole (Nexium) and pantoprazole (Protonix). They measured the acidity of the environment around the tumor and then exposed the cell lines to the cancer drugs. Finally, they evaluated the growth of the tumors in the laboratory.
Pre-treating the tumor cell lines made them more sensitive to the effect of the three cancer drugs studied -- cisplatin, 5-fluorouracil and vinblastine, the researchers found.
Next, they gave one heartburn medication, omeprazole, orally to mice designed to have melanoma and found it made solid tumors more sensitive to cisplatin. When they followed the animals for one month after treatment, they found the pre-treated tumors started growing again, but they didn't reach the size of tumors in animals that didn't receive the pre-treatment.
Fais said chemotherapy drugs often don't work because they're unable to penetrate tumor cells. Treating a tumor with an proton pump inhibitors before administering a chemotherapy drug neutralizes the environment enough to allow passage of the anti-cancer drug into the tumor cells, he explained.
"Clinicians and drug companies have to newly and seriously take into account the anti-acid treatment of tumors," said Fais, whose team is planning to do a clinical study with cancer patients early next year.
But U.S. cancer experts, including Dr. John Glaspy, a professor of medicine at UCLA's Jonsson Comprehensive Cancer Center, emphasized that the Italian study is very preliminary. While the researchers may be the first to report that pre-treatment with heartburn medication can boost the effectiveness of cancer drugs, Glaspy said, "there are hundreds of substances that in pre-clinical testing either increased or decreased the sensitivity of cancer cells to chemotherapy. The vast majority of these, when tested in people, don't make a difference."
"I hope it bears out," he said, "but the odds are against it."
Dr. Herman Kattlove, a spokesman for the American Cancer Society, agreed. "People have been looking for something to lower cancer cell resistance to drugs for a while," he said. While the proton pump inhibitors concept is "worth thinking about and talking about" and warrants further study, cancer patients shouldn't try to self-dose, he said.
To learn more about chemotherapy, visit the American Cancer Society.