The treatment – called autologous hematopoietic stem cell transplantation (AHSCT) – 'reboots' the patient's faulty immune system, which in MS patients attacks the central nervous system, causing damage to nerve fibres.
While it was already known that AHSCT can reset the immune system and pause the deterioration of MS symptoms, which can range from fatigue, vision problems and spasms to severe disability, it was not known how long the positive effects of AHSCT would last.
'In this study, which is the largest long-term follow-up study of this procedure, we've shown we can "freeze" a patient's disease – and stop it from becoming worse, for up to five years,' said lead author Dr Paolo Muraro, from the Department of Medicine at Imperial College London.
After examining clinical data from 281 people with advanced MS who had received AHSCT between 1995 and 2006, the researchers observed that 46 percent of the patients showed no worsening of symptoms in five years. All the patients had failed to respond to other types of treatment.
However, the procedure carries risk and may not be suitable for all patients. AHSCT involves harvesting stem cells from the patient's body before the remaining immune cells are destroyed with chemotherapy. The patient's immune system is then regrown by transplanting the stem cells back into the body.
There is a risk of infection in the period where the immune system is disabled and, of the 281 patients in the study, eight died in the 100 days following treatment. 'We must take into account that the treatment carries a small risk of death, and this is a disease that is not immediately life-threatening,' cautioned Dr Muraro.
Last year, BBC Panorama reported on the 'miraculous' results of a current trial of AHSCT in Sheffield, which saw patients with severe paralysis regaining movement in just a couple of days (see BioNews 836).
The latest study, published in the journal JAMA Neurology, revealed that young people and those with less advanced MS benefited most from the treatment. The outcome was also strongly dependent on the form of MS being treated. Three out of ever four patients with 'relapsing' MS saw no disease progression compared with one in three with the more severe, progressive form. Some patients even reported improvements in their symptoms.
'These findings are very promising – but crucially we didn't have a placebo group, in this study, of patients who didn't receive the treatment,' said Dr Muraro. 'We urgently need more effective treatments for this devastating condition, and so a large, randomised controlled trial of this treatment should be the next step.'
Dr Sorrel Bickley, head of biomedical research at the MS Society, welcomed the results. 'The findings offer some encouraging insights,' he said. '[MS] is a challenging and unpredictable condition to live with and that's why the MS Society is funding research like this to further our knowledge and find treatments for everyone.'
AHSCT is not routinely available on the NHS and the MS Society says that anyone considering the treatment should speak to their neurologist.
MS is an incurable disease that affects around 100,000 people in the UK and 2.3 million worldwide.