For Kidney Transplant, It's in the Prep
Date: June 15, 2012
Roughly 20,000 patients who need a kidney transplant—about a third of people on the U.S. waiting list—are unlikely candidates because they’re hard to match.
Some earlier event such as a blood transfusion, pregnancy or previous kidney transplant has so sensitized their immune systems that rejecting the grafts would be the rule. Not surprisingly, because of pregnancy, women make up the majority of “HLA-sensitized” patients.
Transplant surgeon Robert Montgomery and Hopkins colleagues, however, have developed a successful end run around the problem: a presurgery protocol that more than doubles a transplant patient’s survival rate from the usual 30 percent to 80 percent eight years later. “If this were a cancer drug that doubled chances of survival,” he says, “people would be lined up out the door to get it.”
Montgomery preconditions patients before transplant. They’re desensitized to the HLA antigens in the donor kidney that they’ve become able to attack. This wide-scale damping down begins with outpatient plasmapheresis sessions to scrub blood of circulating anti-HLA antibodies. Also, at each session patients are infused with low-dose immune globulin (IVIg)—a tactic to dilute antibody undesirables as well as discourage output of new ones.
The process, which conditions the body to accept the new kidney, is performed every other day for several days before transplant and then up to 10 days following surgery. After that, patients get the same anti-rejection medication anyone gets with kidney transplant. Historically, highly HLA-sensitized patients have been transplant’s bad dream, with fewer than 7 percent each year receiving the surgery. With preconditioning, that figure at Johns Hopkins is now a dramatic 98 percent.
“We’ve had the protocol for some time,” Montgomery says. He and his team pioneered it for kidney transplant in 1998 and many hospitals have made it their own. But having no follow-up data on the technique beyond two years, and small but confounding differences in practice at various surgery sites made outcomes hard to compare. Now results of a new long-term study of 211 transplanted HLA-sensitized patients—one that sorted out major design glitches—confirms that what the surgeons suspected is true.
“Our study shows long-term survival benefit from desensitization,” says Montgomery of the work, published in The New England Journal of Medicine. “Preconditioning increases survival, ensures a better lifestyle and saves money. There aren’t many things like that.”
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