Update on bone marrow transplants for MS
Bone marrow transplantation (BMT) is a high-risk treatment for people with rapidly worsening multiple sclerosis but improvements in technique have made the procedure safer, according to new data presented at the European Academy of Neurology annual meeting in May.
People with MS have a dysregulated immune system. While disease-modifying therapies can modulate the immune response, this approach may not be successful in people with severe relapsing-remitting MS (RRMS) who are at risk of significant disability over the next few years.
BMT (also called stem cell transplantation) is procedure that wipes out the immune system and rebuilds from scratch. This is a three-step process. First, drugs are administered to stimulate stem cells (which form blood cells, including immune cells) to exit the bone marrow. These stem cells are harvested and frozen. Secondly, powerful immune-suppressing drugs eliminate the body’s immune system. Thirdly, the frozen stem cells are injected back into the person’s body so they can regrow a new immune system. Since the person’s own stem cells are used (called autologous), there is no risk of tissue rejection. It is a gruelling procedure and is associated with significant risks, such as infections and death, so it’s generally tried in a small number of people.
An Italian study looked through its records to look at the outcomes of 206 people with MS who underwent BMT over a 20-year period (Boffa and colleagues. EAN 2020; abstract EPR1153). People were followed up for a median of four years. Overall, 69% had no disability worsening in the 10 years after BMT, 71% had no relapses and about 50% of people with RRMS showed an improvement in their level of disability. Unfortunately, the procedure was less successful for people with progressive MS: only 18% showed improvement and 75% had a worsening of their disability. The mortality rate was 1.5%, but there have been no deaths since 2007.
These results are somewhat better than the pooled results of 281 MS patients from 13 countries (including Canada) who had a BMT (Muraro and colleagues. JAMA Neurol 2017;74:459-469). The median follow-up was 6.6 years. People in this study were generally worse than those in the Italian study: 78% had progressive MS and many had severe disability. Overall, 46% had no worsening of their disability in the five years after transplantation. Eight people died, for a mortality rate of 2.8%. Older people and those with severe disability had worse outcomes compared to younger people with RRMS.
An analysis of all published studies for the period 1995-2016 found that younger people with aggressive RRMS were the ones most likely to benefit from BMT (Sormani and colleagues. Neurology 2017;88:2115-2122). The risk of death was higher in older people, those with progressive MS (who are generally older) and a higher level of disability. Overall, about 1 in 4 people had worsening disability in the five years after BMT. The risk of progression was much lower in the subgroup of people with RRMS.
These results suggest that “rebooting” the immune system may be able to stop RRMS in its tracks – at least for a time. However, it is less effective for people with progressive forms of MS (which is driven by different disease processes), and it cannot restore what has already been lost in terms of nerve damage and disability in people with advanced MS. Future studies are likely to focus on younger people with severe RRMS who are earlier in their disease course and haven’t responded to one of the potent MS drugs. These are the people who are most likely to benefit and who will have the lowest risk of dying from the procedure.
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