• If untreated 80% of people with relapsing MS are likely to convert to secondary progressive MS within 20 years.
  • This study shows that disease modifying therapies (DMTs) significantly decrease the probability of converting from relapsing remitting MS to secondary progressive MS.
  • Early treatment also has a marked effect on reducing the probability of developing secondary progressive MS.

Historical studies have suggested that around 80% of people with relapsing remitting MS are likely to enter the secondary progressive phase of the disease within 20 years if left untreated. Secondary progressive MS (SPMS) is characterised by a continual accumulation of disability without any periods of remission. In more recent decades, since the arrival of effective disease modifying MS therapies, clinicians have observed an apparent decline or delay in people reaching the secondary progressive MS phase. However, data-driven research to confirm this observation has been hard to come by.

Results from an international study led by Associate Professor Tomas Kalincik of the University of Melbourne, in partnership with UK researchers, has now shown that treatment with disease modifying therapies does decrease the risk of people converting from relapsing remitting MS to secondary progressive MS.This effect is shown to be heightened if treatment starts within 5 years of onset.

The different disease modifying treatments on trial

This study published in the Journal of the American Medical Association (JAMA) looked at whether current medications are preventing or delaying the conversion to secondary progressive MS. The team used sophisticated statistical techniques to account for differences between individuals in terms of age, gender, disease duration, disease severity, and, for the first time, used a much clearer definition of secondary progressive MS that has been lacking in previous studies.

The effect of a number of different treatments, including interferon, natalizumab, alemtuzumab, glatiramer acetate and fingolimod were investigated. Each of these treatments were associated with a significantly lower probability of converting to secondary progressive MS.

This large study was conducted using a group of 1,555 individuals who were tracked in several studies. These included the international MSBase clinical database, five European centres which had been using alemtuzumab for an extended period, and the medical records of a group of untreated people with MS who were followed at the University Hospital of Wales, United Kingdom.

Some types of medications did appear to have more impact in reducing the probability of someone with relapsing remitting MS converting to secondary progressive MS. Interferon beta and glatiramer acetate had a smaller effect in preventing or delaying secondary progressive MS than disease modifying treatment such as fingolimod, alemtuzumab and natalizumab, which are considered to be higher efficacy therapies.

Results of the study

The results showed that at 5 years, 7% of those on the higher efficacy therapies converted to secondary progressive MS, compared to 12% on the lower effect treatments, and at 9 years, the results showed a 16% conversion rate versus 27% conversion rate to secondary progressive MS.

The scientists also explored the effect of when the medication was initiated after disease onset. They found that the risk of converting from relapsing remitting MS to secondary progressive MS was significantly lower for people who had received early treatment than late treatment. Of those who began on glatiramer acetate or interferon beta within 5 years of disease onset, only 29% converted to secondary progressive MS after 17 years, compared to 47% of people who started these treatments more than 5 years after onset.

This study provides evidence that early treatment with a disease modifying treatment, in particular the more effective medications, can have a large effect on reducing the risk of people with relapsing MS going on to develop secondary progressive MS.

The authors note that the study did not look at the potential side effects or risks associated with MS medications, and so individuals and neurologists still need to weigh these potential benefits against the potential risks when considering MS treatments. However, these findings may help people make a more informed decision when choosing medications.

With thanks to MS Research Australia – the lead provider of research summaries on our website.