Rockville, MD - The US FDA has approved a diagnostic blood test, AlloMap (XDx, Brisbane, CA), to help identify heart-transplant recipients who might be at risk of organ rejection [1]. AlloMap measures the activity of genes related to allograft rejection, allowing patients to potentially avoid invasive endomyocardial biopsies and improving clinicians' ability to make management decisions.

The test, which assays the RNA levels of 11 rejection biomarker genes and nine control genes, was clinically validated using data from nine leading heart-transplant centers participating in the Cardiac Allograft Rejection Gene Expression Observational (CARGO) study, as previously reported by heartwire.

One of the principal investigators of CARGO, Dr Howard J Eisen (Drexel University School of Medicine, Philadelphia, PA), told heartwire that although the test has been available for some time—his center started using it about three and a half years ago—"the issue has been overall acceptance: some people were waiting for FDA approval to legitimize it." Eisen says the test "has not eliminated all biopsies" among heart-transplant recipients at his center, but he estimates it has reduced them by up to 75%.

He likens AlloMap to the prostatic-specific antigen (PSA) test for prostate cancer, "which was basically developed as a screen to determine whether people needed to be biopsied or not."

AlloMap also helps physicians make decisions because it measures immune activation, he notes. So, for example, it can help pinpoint patients who are noncompliant with their immunosuppressant medication or help doctors tailor the doses of immunosuppressants for individual patients.

"This test and others—such as some available for breast cancer—represent the beginning of a new era in molecular diagnostics," he added, noting that a test similar to AlloMap is being developed for lung-transplant recipients.

AlloMap is only the third test to be approved as an in vitro diagnostic multivariate assay, notes the FDA.