Grapefruit juice boosts the anti-cancer effects of the drug rapamycin, a new study has found.
In a small, early clinical trial, researchers at the University of Chicago Medical Center found that combining eight ounces of grapefruit juice with the drug rapamycin can increase drug levels, allowing lower doses of the drug to be given.
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In data presented at the AACR 100th Annual Meeting 2009, the Chicago researchers examine ways to exploit the fruit's medication-altering properties.
"Grapefruit juice can increase blood levels of certain drugs three to five times," said study director Ezra Cohen, MD, a cancer specialist at the University of Chicago Medical Center.
"This has always been considered a hazard. We wanted to see if, and how much, it could amplify the availability, and perhaps the efficacy of rapamycin, a drug with promise for cancer treatment," Ezra added.
The trial was designed to test "whether we could use this to boost rapamycin's bioavailability to the patient's advantage, to determine how much the juice altered drug levels, and to assess its impact on anti-cancer activity and side effects," he said.
The study followed 28 patients with advanced solid tumors, for which there is no effective treatment. The dose of the drug increased with each group of five patients, from 15 milligrams up to 35. Patients took the drug by mouth, as a liquid, once a week.
Beginning in week two, they washed it down with a glass of grapefruit juice (Citius paradisi), taken immediately after the rapamycin and then once a day for the rest of the week.
Twenty-five participants remained in the study long enough to be evaluated. Seven of those 25 had stable disease, with little or no tumor growth. One patient had a partial response, with the tumor shrinking by about 30 percent. That patient is still doing well more than a year after beginning the trial.