A treatment to filter out antibodies from kidney patients' blood before their transplant surgery could double survival rates in certain hard-to-match transplant patients, a new study says.
These patients, mostly women, are typically ineligible for kidney transplants — their risk of rejecting a new organ is very high, so they need to be even more closely matched to a donor than usual.
The new treatment could lower their risk of rejection, and potentially boost the number of living donor kidney transplants performed each year by 2,000 to 3,000, the researchers said.
"That would be the single biggest increase in live donor transplantation that we've had in several decades," said study researcher Dr. Robert Montgomery, a professor of surgery at The Johns Hopkins University School of Medicine.
The study will be published tomorrow (July 28) in the New England Journal of Medicine.
A risk too high
About 1 in 3 kidney transplant patients are very likely to reject a new organ. That's because they have previously been exposed to foreign tissue, either from a blood transfusion, pregnancy or a previous organ transplant, and their immune systems are now primed to mount a swift, forceful attack against a donor organ.
Even organs that are closely enough matched that other patients' bodies would accept them would be attacked by these patients' bodies, so their pool of potential donors is extremely narrow.
And because exposure to foreign tissue happens during pregnancy — in effect, a woman's immune system sees her fetus as foreign — the condition disproportionally affects women.
It's hard to find compatible kidneys for these patients, and fewer than 7 percent receive transplants each year.
In the new study, the researchers filtered the blood of 211 hard-to-match kidney transplant patients, two-thirds of whom were women. First, the patients' blood cells were separated from the blood plasma. Then, patients received a new plasma supply, and new antibodies. The process was performed several days before the transplant and can continue for more than a week after surgery.
For each patient who received a transplant after this therapy, the researchers identified five patients on the kidney transplant waiting list with similar characteristics, to use as a control group.
After eight years, 80.6 percent of those who received the antibody therapy were still alive. Of those who remained on the waiting list, 30.5 percent survived. The long-term survival rate is low for those who remain on dialysis because the process puts a lot of wear and tear on the body, and can cause such complications as infections and high blood pressure, the researchers said.
"Dialysis is not a perfect replacement for a kidney," Montgomery said.
Montgomery estimated that 20,000 kidney transplant patients in the United States fall into this hard-to-match group. He hopes the new data will boost the number of patients who receive the antibody therapy.
In all, there are about 85,000 patients waiting for a kidney, Montgomery said. While the antibody therapy won't completely solve the problem of organ availability, it may increase the number of patients getting transplants, Montgomery said.
"It will help us to further optimize the organs that are available, that [otherwise] can't be used because of these incompatibilities," Montgomery said.
At this point, the therapy can be used only when the patient has a living organ donor, because the therapy needs to be done before the surgery, and patients who receive organs from deceased donors have little warning of when their organ will be available.
Pass it on: An antibody therapy may increase the number of kidney transplant patients who are able to receive organs.