Disappointingly, formal clinical trials have failed to show any efficacy of the drugs for relapsing remitting MS (RRMS), in slowing disability progression specifically in people with secondary progressive MS (SPMS).
Despite this, many people continue to use these anti-inflammatory drugs even after the transition to SPMS, despite the lack of strong evidence for any benefit.
In a recent study published in the scientific journal Neurology an international team of researchers have used the very powerful international observational clinical database known as MSBase to further examine, in a real-world setting outside of clinical trials, whether there may be any evidence to support the continued use of MS medications in secondary progressive MS.
MSBase contains detailed clinical information about diagnosis, medications and clinical outcomes including disability progression for over 52,000 individuals with MS from over 50 countries.
In this study led by Dr Johannes Lorschieder, from the University of Melbourne, Australia, they selected patients from MSBase who had been diagnosed with SPMS, which included a total of 2,381 people. Of those 1,002 were receiving no treatment and 1,379 were receiving some type of disease modifying treatment on the day they fulfilled the diagnostic criteria for SPMS.
The individuals were carefully matched on all other disease characteristics. The researchers looked at the clinical progression data of the two groups over an average follow up period of just over two years, to see if there were any differences. They found very little difference in the proportion of patients free from disease progression between the two groups, and the risk of disease progression was similar for those receiving treatment and those not receiving any treatment. Additionally the proportion of patients who developed new lesions during the follow-up period was also very similar in both groups.
The scientist concluded that, in the short term, there appears to be no benefit in continuing to use RRMS medications following the transition to SPMS.
However, it is important to note that this study compared no treatment with all types of disease modifying therapies together. Further research is need to identify if specific types of treatment, such as some of the newer highly effective therapies, if analysed separately, may show an effect.
The mechanism of conversion from RRMS to SPMS is still poorly understood. Whether the same parts of the immune system are involved in relapses and in progression is not clear. The results here add evidence to the suggestion that immune suppressive therapies generally do not stop disability progression at least in the short term. The participants in this study were followed for a relatively short time-frame which may have masked a slower more long-term effect in dampening down progression. Some previous studies have suggested that there may be a ‘therapeutic lag’ in SPMS, in that the effects of medications may take some time to kick-in – a little like putting the brakes on a fast-moving juggernaut – it takes a while to stop! Some studies suggest that this lag can be up to five years before a medication effect becomes apparent. To this end, longer term studies are greatly needed.
Despite these caveats, this study does highlight the desperate need to truly define the mechanisms of progressive disease and develop targeted new therapies to stop progression. Accelerating this work is the goal of the global collection of MS organisations that have united to form the International Progressive MS Alliance.
With thanks to MS Research Australia – the lead provider of research summaries on our website.