Test may let transplant patients skip biopsies
CHICAGO (Reuters) - A gene-based blood test worked as well as a surgical procedure used to check for signs of rejection in patients with heart transplants, U.S. researchers said on Thursday.
They said the simple blood test called AlloMap, made by molecular diagnostics company XDx Inc, will allow heart transplant patients to forego frequent biopsies of the heart, a procedure dreaded by many transplant patients because it is uncomfortable and can damage heart valves in a few patients.
"This represents a major step forward in the way we manage a patient after heart transplants because we can now safely reduce the numbers of heart biopsies," said Dr. Hannah Valantine of Stanford University, who designed the study to determine whether it was safe to reduce the number of necessary biopsies by using the blood test.
Valantine and colleagues presented the findings at the International Society for Heart & Lung Transplantation annual meeting in Chicago.
Heart transplant patients need to be monitored regularly for signs of organ rejection, typically through a procedure called an endomyocardial biopsy, in which doctors insert a tube into a vein in the neck and into the heart, where tiny bits of tissue are collected and tested.
Heart transplant recipients typically get 15 to 20 biopsies in the first six months after a transplant, and two to four biopsies per year after that.
"We need to monitor patients very carefully to detect a rejection so that we can treat it in a timely fashion and prevent the heart from failing," said Valantine, whose study was published online in the New England Journal of Medicine.
She said biopsies are invasive and uncomfortable and are associated with a low risk of complications and death.
"The patients dislike them and there is a huge cost burden to institutions," Valentine said, noting that the biopsy costs $4,000, about $1,000 more than the AlloMap test.
The study was funded by XDx, a molecular diagnostics company in Brisbane, California.
Valantine said doctors have been doing the biopsy procedure for 30 years. Her study compared that procedure to the AlloMap test, which checks the blood to see if specific genes associated with rejection are turned on or expressed.
The team compared results of 600 patients who were randomly assigned either to have a biopsy or to have an echocardiogram and the AlloMap test.
Valantine said the blood test worked as well as routine biopsies, with patients in the blood test group showing similar rates of rejection and other complications to those who got biopsies.
Researchers are also doing a cost analysis comparing the two procedures, but those results are not yet available.
The blood test is currently offered at 65 transplant centers in the United States. The U.S. Food and Drug Administration approved it for heart transplant patients in August 2008.