A blood test commonly used to determine whether or not heart-transplant recipients are rejecting their new organ can also predict potential rejectionrelated problems in the future, a UCLA-led study finds. The researchers demonstrated how the AlloMap test, which uses a blood sample to measure changes in the expression of roughly a dozen genes, can be used over a period of time to assess the risk of dysfunction or rejection of a transplanted heart — months before such an event may occur.
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“For the first time, we can use genomic testing over multiple patient visits to go beyond intuition to understand not just how patients are doing now, but also how they are likely to be a few months from now,” says Mario Deng, MD, medical director of UCLA’s Integrated Advanced Heart Failure-Mechanical Support-Heart Transplant Program. “It’s another step toward personalized medicine.”
The discovery that the white blood cells of transplant recipients contain this prognostic information on rejection, independent of how their transplanted heart may be functioning, could potentially improve care and outcomes, the researchers said.
AlloMap, which is based on research led by Dr. Deng in conjunction with more than a dozen of the largest U.S. heart-transplant centers and the Brisbane, California-based biotech company XDx, measures the expression levels of 11 genes from a patient’s blood sample, each of which is known to be associated with rejection risk. The current study is based on data originally collected by leading transplant centers and published in the New England Journal of Medicine in 2010. For that study, 600 heart-transplant recipients were randomly assigned to be monitored for potential episodes of rejection either through routine biopsy or through the AlloMap test. The study found that AlloMap was equally as effective as biopsy at detecting rejection or dysfunction, and it resulted in increased patient satisfaction because it was less invasive. The new study demonstrates for the first time the ability of the AlloMap test, when used over time, to predict future events.
Dr. Deng and colleagues noted that using gene-expression profiling to predict the future likelihood of patients experiencing rejection-related problems with their transplanted heart could change the way such patients are treated. For example, those deemed to be at low risk for adverse events could be given lower doses of immunosuppressive drugs, which could reduce the significant side effects. Or patients found to be at high risk could be evaluated at shorter time intervals to determine the causes of the test-result variability, specifically to rule out rejection.
“Utility of Gene Expression Profiling Score Variability to Predict Clinical Events in Heart Transplant Recipients,” Transplantation, January 31, 2014