MONDAY, Dec. 29, 2014 (HealthDay News) -- An experimental therapy that kills off and then "resets" the immune system has given three years of remission to a small group of multiple sclerosis patients, researchers say.
About eight in 10 patients given this treatment had no new adverse events after three years. And nine in 10 experienced no progression or relapse in their MS, said lead author Dr. Richard Nash of the Colorado Blood Cancer Institute at Presbyterian/St. Luke's Medical Center in Denver.
"I think we all think of this as a viable therapy," Nash said. "We still need to perform a randomized clinical trial, but we're all pretty impressed so far, in terms of what we've seen."
In multiple sclerosis, the body's immune system for some unknown reason attacks the nervous system, in particular targeting the insulating sheath that covers the nerve fibers, according to the U.S. National Institutes of Health. People with the more common form, called relapsing-remitting MS, have attacks of worsening neurologic function followed by partial or complete recovery periods (remissions).
Over time, as the damage mounts, patients become physically weak, have problems with coordination and balance, and suffer from thinking and memory problems.
This new therapy seeks to reset the immune system by killing it off using high-dose chemotherapy, then restarting it using the patient's own blood stem cells. Doctors harvest and preserve the patient's stem cells before treatment, and re-implant them following chemotherapy.
"Because many of the immune cells are being killed off, there's an immune reset following the treatment," Nash said.
Nash and his colleagues came up with the idea based on similar treatment that blood cancer patients receive. "We knew what a profound effect the high-dose therapy and transplant could have on the immune systems of patients with lymphoma and myeloma," he said.
Three years ago, a group of 24 patients with relapsing-remitting MS underwent the therapy. Researchers plan to follow them for five years, to see how well the treatment performs.
So far, 78 percent of the patients have been event-free, which the researchers define as survival without death or disease from a loss of neurologic function, clinical relapse or new nervous system lesions caught on imaging scans.
About 90 percent of patients have enjoyed progression-free survival, and 86 percent have not suffered a clinical relapse, the researchers reported Dec. 29 in JAMA Neurology.
Nash said this therapy could revolutionize treatment for multiple sclerosis, which has depended on expensive biologic and targeted therapy drugs that block the immune system.
"The agents we use aren't expensive. The major expense is the supportive care," Nash said, noting that the adverse reactions and health risks are the same as those experienced by cancer patients receiving bone marrow or stem-cell transplants. "Everything else has just gotten so much more expensive, in terms of the agents out there. Treating MS may have become more cost-effective."
However, Nash noted that the therapy still has not been proven to create lasting improvement. "I'm sure we're going to be getting a lot of phone calls from patients, but we're still in the investigative stage for this," he said.
Another expert agreed. Bruce Bebo, executive vice president for research at the National Multiple Sclerosis Society, said that the research is interesting but needs more follow-up.
"There may be something to this, but the jury is out until we see results from a larger, better-controlled trial," he said.
Bebo also said this approach will have to be tested against current MS drug therapies.
"It comes with significant risk. They're using pretty strong chemotherapy drugs to wipe out your immune system, and it does come with a risk of mortality," he said.
During the past two decades, several hundred MS patients have received similar experimental treatment, said the authors of an accompanying journal editorial, Dr. Mateo Paz Soldan of the University of Utah and Brian Weinshenker of the Mayo Clinic in Rochester, Minn.
In those earlier studies, progression-free survival has ranged from less than 40 percent to nearly 80 percent at two to three years. "The longer the follow-up, the lower the chances of the disease remaining progression-free," they wrote.
For more on multiple sclerosis, visit the U.S. National Library of Medicine.