Kidney transplants could become more common thanks to a treatment that… (Spencer Weiner/Los Angeles…)
More than 20,000 of the roughly 82,000 people waiting for a kidney transplant in the United States have the odds stacked against them because they are what doctors call “HLA sensitized.” That means that a previous transplant, blood transfusion or pregnancy has primed their immune systems to reject a donor organ that isn’t a perfect match.
But a work-around developed at Johns Hopkins University in Baltimore could improve the fortunes of these patients. Researchers there have figured out a way to erase their bodies’ memory of being HLA sensitized, in most cases clearing the way for a successful transplant from a donor who isn’t a perfect match.
Here’s how the treatment works, according to this explainer from Johns Hopkins Medicine’s Comprehensive Transplant Program:
Harmful antibodies are removed with a process called plasmapheresis, a procedure similar to dialysis that removes the plasma portion of the blood where antibodies are located. The number of plasmapheresis treatments required by the recipient before surgery varies depending on the amount of harmful antibodies in their blood.
After each plasmapheresis the recipient receives an intravenous infusion of immune globulin to replace antibodies needed to fight infections and help prevent harmful antibodies from returning. Once the antibodies against the donor’s blood type decrease to very low levels, the transplantation can take place.
In a study released Wednesday by the New England Journal of Medicine, the Hopkins team reported that their desensitization procedure worked on 211 of 215 patients treated from February 1998 until December 2009. Over time, those 211 patients fared much better after their transplant surgeries than similar patients who didn’t get the treatment, many of whom remained stuck on the transplant list.
Among those 211 patients, 91% were still alive after one year, 86% were alive after three years, and 81% were alive after five years and after eight years.
Each of those 211 patients was matched with five control patients who were on the United Network for Organ Sharing’s waiting list for a donor kidney. The control patients were similar in age, race, sex, number of years on dialysis, number of prior transplants and other factors. Among these patients, 93% were alive after one year, 77% were alive after three years, 66% were alive after five years and 49% were alive after eight years.
The researchers also looked at a subset of the control patients who never got off the waiting list over the course of the study. For this group, the numbers were even worse – 91% were alive after one year, 67% were alive after three years, 52% were alive after five years and only 31% were alive after eight years.
Though all patients did roughly the same in the first year, the benefits of desensitization – and the subsequent transplants – kicked in later. The more time that passed, the bigger the benefit.
That’s not to say that desensitization therapy was always a walk in the park. Nearly 11% of patients who went through it experienced minor side effects, including rash, itching, headache, nausea and shortness of breath. Three of the 215 patients had serious side effects, including an allergic reaction that led to dangerous swelling of the airway.
Still, the researchers emphasized, the benefits clearly outweighed the risks. In addition, if the approach were widely adopted, HLA-sensitized patients could get kidney transplants sooner and spend less time on dialysis, which would also improve their overall survival.
In a statement released by Hopkins, study leader Dr. Robert A. Montgomery estimated that desensitization therapy could pave the way for about 3,000 additional kidney transplants from living donors each year. Living donors must be used because patients need to be able to plan and prepare for their transplants; organs from donors killed in accidents must be used right away.
“Desensitization has the potential to greatly increase access to transplantation” to patients who would otherwise be hard to match with kidney donors, and “to increase their longevity,” they wrote in their study.