Gene Expression Test Rules Out Transplant Rejection

A new study confirms that a simple blood test that analyzes a patient's genes can accurately detect the absence of heart transplant rejection.

A team of international heart transplant experts from over 20 institutions has published the results of the Cardiac Allograft Rejection Gene Expression Observational (CARGO) study on the utility of AlloMap molecular expression testing, a gene expression profiling (GEP) test currently offered at 40 transplant centers in the United States. Based on the new data, in more than 99% of cases, the AlloMap test successfully predicted the absence of moderate or severe acute cellular organ-transplant rejection. The new study was published as an invited editorial in the December 2006 edition of the Journal of Heart and Lung Transplantation (JHLT).

The AlloMap test uses real-time polymerase chain reaction (PCR) and an algorithm to analyze the patient's gene expression. The test rules out rejection, meaning that a low test score very reliably identifies the transplant patient who is not rejecting the transplanted heart. The primary advantage of the test is to identify low-risk patients who can be monitored and managed using noninvasive methods and who may benefit from being more aggressively weaned off intensive immunosuppressive regimens that are associated with serious side effects.

The AlloMap test was developed by XDx (San Francisco, CA, USA) and is also being examined for use in lung transplantation. Similar approaches are being used to create new molecular diagnostic tests for the improved clinical management of immune-mediated inflammatory diseases, such as systemic lupus erythematosus (SLE).

AlloMap testing is not only less invasive and less risky than biopsy, it also monitors the absence of organ rejection and raises the suspicion of damage before any damage to the heart happens. Biopsy records damage that has already occurred,” said lead author Dr. Mario Deng, director of cardiac transplantation research and associate professor of clinical medicine at Columbia University College of Physicians and Surgeons (New York, NY, USA).

Before the availability of AlloMap testing, heart-muscle biopsy was the only method available for detecting rejection of the transplanted heart. Invasive heart biopsies are performed frequently in the first year post-transplant and periodically thereafter, often for the patient's lifetime.



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