ROCKVILLE, Md., Aug. 27 -- The FDA has approved a non-invasive molecular test for signs of rejection after a heart transplant.
The so-called AlloMap, made by XDx of Brisbane, Calif., measures expression of 20 genes in immune cells, leading to a score that can give clinicians guidance as to the likelihood of rejection, the agency said.
The test uses a real-time, quantitative polymerase chain reaction assay to measure the gene expression in white cells in a blood sample, which is then combined with a proprietary mathematical algorithm to generate the score, the company said.
Scores range from zero to 40, and the lower the score -- compared with patients in the same post-transplant period -- the lower the probability of rejection at the time of testing.
"AlloMap can help contribute to an appropriate treatment plan by identifying those patients not experiencing postoperative heart transplant rejection," according to Daniel Schultz, M.D., director of the FDA's Center for Devices and Radiological Health.
"It is an example of how advancements in science and technology are leading to new medical care diagnostics," he said.
Currently, clinicians often monitor patients for rejection with heart biopsies, but such procedures are difficult and can be risky.
According to the National Heart, Lung, and Blood Institute, the FDA said, half of all rejections happen during the first six weeks after surgery and 25% of patients have signs of possible rejection at least once during the first year following a transplant.
The AlloMap test was developed using blood and biopsy samples and other information collected from heart transplant recipients at nine U.S. heart transplants centers that took part in the Cardiac Allograft Rejection Gene expression Observational study (CARGO).
The study had data on 153 patients on 300 medical visits at various times after their heart transplants.
According to the American Heart Association, there were more than 2,000 heart transplants performed in the United States during 2006.