Researchers suggest that a combination of high-dose chemotherapy and stem cell transplantation could lead to long-term remission of RRMS.
Study co-author Dr. Richard Nash - of the Colorado Blood Cancer Institute and the Presbyterian-St. Luke's Hospital in Denver, CO - and colleagues recently reported the final results of their phase II trial (called HALT-MS) in the journal Neurology.
MS is a disease whereby the immune system mistakingly attacks myelin - the fatty substance that protects nerve fibers in the central nervous system - and the underlying nerve fibers. This interferes with signaling between the brain and spinal cord.
This disruption can cause muscle weakness and stiffness, problems with walking and balance, and chronic pain. People with MS may also experience fatigue, dizziness, cognitive deficits, and vision problems.
In RRMS, patients experience inflammatory attacks on myelin and the nerve fibers - referred to as "relapses" - and symptoms of MS arise. These relapses are followed by periods of complete or partial remission, whereby some or all of the symptoms disappear.
There is no cure for RRMS, but there are a number of medications that can help patients to manage relapses and symptoms.
However, the results of the new study suggest that one-time high-dose immunosuppressive therapy (HDIT), followed by autologous hematopoietic cell transplantation (HCT), may lead to long-term remission for patients with RRMS.
Most RRMS patients in remission 5 years after HDIT/HCT
The goal of HDIT/HCT is to remove all MS-causing cells from the body.
The therapy involves collecting a patient's blood-forming stem cells, before treating them with high-dose chemotherapy to destroy their immune system. The blood-forming stem cells are then returned to the patient, effectively "resetting" their immune system.
In 2014, Dr. Nash and colleagues reported the 3-year results of their phase II clinical trial for HDIT/HCT. The trial involved 24 patients with RRMS aged between 26 and 52. All patients were using currently available medications for their condition, but none were experiencing a reduction in relapses or disease progression.
For the trial - funded by the National Institute of Allergy and Infectious Diseases (NIAID) - each patient received HDIT/HCT. The team found that almost 80 percent of patients experienced no relapses, worsening of disability, or new brain lesions in the 3 years following treatment.
In the new study, the researchers assessed the same group of patients 5 years after HDIT/HCT. They found that 69 percent of patients had still not experienced relapses, disability progression, or new brain lesions since the treatment.
Importantly, none of the patients had used any RRMS medications since treatment with HDIT/HCT.
Reported side effects of HDIT/HCT included cytopenias (a reduction in blood cells) and infections. Three patients died during the 5-year follow-up, but the researchers say that their deaths were not related to their treatment.
While further studies are needed to better determine the safety and efficacy of HDIT/HCT for the treatment of RRMS, Dr. Nash and team are encouraged by the results so far.
"If these findings are confirmed in larger studies, HDIT/HCT may become a potential therapeutic option for patients with active relapsing-remitting MS, particularly those who do not respond to existing therapies."
Dr. Daniel Rotrosen, director of the Division of Allergy, Immunology and Transplantation, NIAID