Transplant Drug Has Good, Bad Side
Daclizumab lowers rejection in heart patients but raises infection dangers
WEDNESDAY, June 29, 2005 (HealthDay News) -- A drug that stops the immune system from attacking a newly transplanted heart also increases the risk of life-threatening infections in some patients, researchers report.
The drug, daclizumab (marketed as Zenapax), has already proven successful in kidney transplants and works by blocking immune cells that attack foreign tissue. And in a trial that included 434 heart transplant patients, the drug did decrease the rate of rejection, say researchers reporting in the June 30 issue of the New England Journal of Medicine.
Only 25.5 percent of the patients who got daclizumab experienced rejection in the first six months after the surgery, compared to 41.3 percent of those who got a placebo, according to the study, which was funded by the drug's maker, Roche Laboratories.
However, six of the patients placed on the drug died of infections. No such deaths occurred in the placebo group.
The reaction of cardiologists to those numbers differs greatly.
"I am certain that I would not be willing to trade even a small increase in the risk of death from infection for a reduction in the risk of histologic rejection," Dr. Jeffrey D. Hosenpud, a cardiologist at St. Luke's Medical Center in Milwaukee, commented in an accompanying editorial.
But study lead researcher Dr. Ray E. Hershberger, a transplant cardiologist at the Oregon Health and Science University, has a different view. According to Hershberger, the study shows that infection risk was increased only in patients who got both daclizumab and another form of therapy, called cytolytic therapy. Cytolytic treatment is aimed not at blocking the immune cells, but at killing them, he said.
It took "an enormous amount of effort" sifting through the study data to establish that connection, Hershberger said. The use of daclizumb plus cytolytic therapies in combination for heart transplant patients "should be avoided in usual clinical practice," he said. Roche Laboratories has already issued a warning to that effect.
Hershberger said he does use daclizumab in his practice -- but with great care. "We use this antibody and all others selectively," he said. "We tailor therapy to every patient. In heart transplantation, one size does not fit all."
Dr. Randall C. Starling, director of the Cleveland Clinic's heart failure and transplant program, who took part in the study, said essentially the same thing. "We do not use any type of antibody preparation for all of our patients," he said. "We use them selectively."
Starling is not ready to write off the clinical value of avoiding transplant rejection episodes. The study added valuable information about immune therapy, he said, because "this is the largest randomized trial to test whether such an antibody is efficacious." But the final word on the treatment is still not in, Starling said.
"Only with time and extended follow-up will we know if reducing rejection up front translates into better survival over the long run," he said.
You can learn more about daclizumab from the National Library of Medicine.