FDA Approves Test For Heart Transplant Patients

The Food and Drug Administration (FDA) has just opened doors for more extensive use of a blood test that can greatly reduce the need for heart transplant patients to undergo repeated biopsies that monitor for possible organ rejection.

The test, known as AlloMap, analyzes the ribonucleic acid levels of 11 rejection biomarker genes and nine control genes contained in white blood cells that are associated with the control of cellular chemical activities. White blood cells are the immune system's primary defense against viruses, bacteria and other germs. However, these cells can sometimes turn against a transplanted organ with life-threatening effects.

Rejection occurs when a transplant recipient's body begins attacking the new organ as a foreign entity. According to the FDA, half of all rejections occur in the first six weeks after transplant, and about one-quarter of recipients have evidence of rejection within the first year

XDx, Inc., located in Brisbane, California, is the company that developed the test. XDx's chief medical officer, Dr. James Yee, explained that the test is non-invasive and only requires a simple blood sample. He said that the test is especially useful in detecting a "silent rejection" in which there are no evident symptoms. The cost of the test is $2,950. With the AlloMap test, once a patient's blood sample has been examined in the lab, it is assigned a score that informs doctors of the likelihood that the body is rejecting a transplanted heart.

Heart transplant patients must visit their doctors quite frequently to be closely monitored for signs of organ rejection. Until now, doctors have relied only on a biopsy to watch for signs of rejection. The procedure can be hard to perform and risky for the patient. The process involves using a tiny probe inserted through a vein to cut away a minute amount of heart tissue to be analyzed by a pathologist. The cost of each biopsy ranges between $3,000 and $4,000. Although the AlloMap test cannot eliminate the need for all biopsies, some experts estimate it can reduce the need by up to 75 percent.

AlloMap can also assist doctors in pinpointing patients who are noncompliant with their immunosuppressant medication and allow them to tailor the doses of immunosuppressants to the needs of individual patients.

More than 2,000 heart transplants were performed in the United States in 2006, according to the American Heart Association. Although the AlloMap test was previously approved in 2005 under federal laws that govern clinical labs it has been used at less than half of the heart transplant centers in the United States. It is believed that the FDA approval will increase the number of tests used.