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Orlando, FL (April 14, 2010) — Black kidney transplant patients treated with the immune-system-suppressing drug rapamycin live longer than whites given the same medication, according to research being presented here today at the National Kidney Foundation's Spring Clinical Meetings.
"In selected minorities, particularly in African Americans, there may be a group who benefits from rapamycin," said Dr. Bhamidipati V. R. Murthy of the University of Texas Medical School in Houston, the study's lead author.
Nationwide, rapamycin is the third most commonly-used drug for preventing organ rejection in kidney transplant patients, Dr. Murthy said. Because many of the clinical trials investigating the drug were done at his center, he added, he and his colleagues use rapamycin more frequently; however, they do not use it in patients whose immune systems react more strongly to the presence of a donated organ, or in patients undergoing a second transplant.
Dr. Murthy said he and his colleagues had suspected there might be ethnic differences in kidney transplant patients' response to rapamycin. To investigate, they looked back at 380 patients given the drug who underwent a first kidney transplant at their center between 1993 and 2003, following them up to 2009. Forty-four percent were white, 29 percent were black, and 26 percent were Hispanic.
During follow-up, 106 patients, or 28 percent, died. Even though the black patients were more likely to have high blood pressure and more likely to have been on dialysis for longer before they received a transplant (which is associated with worse outcomes), they were 46 percent less likely to die over the next nine or 10 years than the white patients. The black patients were also heavier, and more likely to reject the donated organ. Hispanic patients were 39 percent less likely to die than whites, although the difference didn't reach statistical significance.
There are a number of factors that could help explain the results, Dr. Murthy said. For one, black patients with end-stage kidney disease are known to survive longer than white patients whose kidneys fail.
Rapamycin is less toxic to the kidneys than other immune-suppressing drugs, he added, so may be better for long-term kidney function. One disadvantage, he added, is that rapamycin can promote high cholesterol levels and high triglycerides; if this occurs, patients can be switched to another immunosuppressant.
Because the study was done at just one center, Dr. Murthy said, it's not clear if the findings have broader applications; he said he would like to examine national data to answer this question. Nevertheless, he added, "we do have a group of patients who benefit from this drug."
The National Kidney Foundation is dedicated to preventing and treating kidney and urinary tract diseases, improving the health and well being of individuals and families affected by these diseases and increasing availability of all organs for transplantation.
For more information about organ donation, transplantation and dialysis contact the National Kidney Foundation at www.kidney.org.