Genomic Assay Predicts Probability of Heart Transplant Rejection

Results obtained over time by a gene expression assay used to monitor heart transplant patients for signs of rejection may be able to predict the likelihood of rejection in the future.

The AlloMap Molecular Expression Test, which is manufactured and performed by the biomedical company XDx (Brisbane, CA, USA), is an in vitro diagnostic multivariate index assay (IVDMIA) testing service. The assay, which is performed in a single laboratory, assesses the gene expression profile of RNA isolated from peripheral blood mononuclear cells (PBMC). AlloMap Testing may be used to evaluate transplant patients aged 15 years or older from at least two months after the transplant. It is intended to aid in the identification of heart transplant recipients with stable allograft function who have a low probability of moderate/severe acute cellular rejection at the time of testing in conjunction with standard clinical assessment.

AlloMap, which measures the expression levels of 11 rejection-related genes from a patient's blood sample, received clearance from the [US] Food and Drug Administration (FDA) in 2008 and it is now routinely used by a majority of American heart transplant centers to monitor low-risk patients during follow-up care, resulting in a substantial reduction in the number of heart-muscle biopsies.

Investigators at the University of California, Los Angeles (USA) recently evaluated data obtained by a study of 600 heart transplant recipients who had been monitored by routine biopsy or with the AlloMap test. They found that the variability of a heart recipient's gene expression profiling test scores over time could provide prognostic utility. This information was independent of the probability of acute cellular rejection at the time of testing.

"The AlloMap was the first FDA-cleared test allowing transplant centers to rule out rejection at the time of the visit," said first author Dr. Mario Deng, professor of medicine at the University of California, Los Angeles. "But until now, it has never been used to predict future events. 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 how they are likely to be a few months from now. It is another step toward personalized medicine."

The study was published in the January 31, 2014, online edition of the journal Transplantation.

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