A small trial in the US which set out to investigate the safety and efficacy of stem cell therapy for patients with multiple sclerosis (MS) has yielded promising results three years into the study. After wiping out the patients’ immune systems and then repopulating them with stem cells, the majority of participants sustained remission of active MS and had improvements in neurological function. However, at this stage it is still unclear whether the treatment can induce long-term suppression of the disease. The results of this phase 2 study can be found in JAMA Neurology.

Multiple sclerosis is one of the most common diseases of the central nervous system, affecting some 2.3 million people worldwide. It’s an inflammatory disease in which the body’s immune system attacks the protective covering of nerves, called myelin. This means that communication between cells of the nervous system is slowed, disrupting the flow of information to and from the brain. The symptoms vary widely, but patients commonly experience muscle weakness, pain, decreased coordination and blurred vision.

The majority of sufferers are diagnosed with a type of MS called relapsing-remitting multiple sclerosis (RRMS), which is the most common form. Patients with RRMS often have attacks when symptoms flare up, which are referred to relapses. This will then be followed by a period of recovery, or remission, during which few or no symptoms are experienced.

There are some drugs available to help reduce disease activity by dampening the body’s immune response, and others can help manage symptoms. However, they can’t stop the long-term progression of disease, and after around 10 to 20 years, many patients will develop a more serious disease called secondary progressive MS. Furthermore, many patients that receive disease-modifying therapies experience breakthrough disease, which is characterized as an unacceptable degree of disease progression.

One type of therapy that researchers have been examining for more than 20 years is autologous hematopoietic cell transplant (HCT), which attempts to reset the immune system by first removing disease-causing immune cells with immunosuppressive therapy, and then replacing them with the patients’ own blood forming stem cells. However, trials on patients with advanced disabilities did not produce positive results.

To find out whether it could be effective if used at earlier stages of MS, researchers enrolled 25 patients with RRMS who experienced relapses while receiving therapies previously. Patients will be evaluated for 5 years, but the results from the 3-year interim analysis are now in.

Almost 80% of participants survived without experiencing any increase in disability or relapse of clinical symptoms, meaning that most remained in remission. Furthermore, this was achieved without giving the patients any MS drugs after the transplant. Some patients experienced adverse effects as expected with immunosuppressive therapy, although these were reversible. According to the researchers, this could suggest that this form of therapy may be beneficial for patients with MS who have not responded to conventional immunotherapy. The trial will continue as planned, which, in conjunction with similar studies, will hopefully serve as a guide for the design of larger trials, which will further evaluate the appropriateness of this particular therapy.

[Via JAMA Network Journals, JAMA Neurology and NIH]