Moderately effective therapies have been the main treatment in pediatric-onset multiple sclerosis for years. Despite the expanding use of highly effective therapies, treatment strategies for pediatric-onset MS still lack consensus. A new study assessed the real-world association of highly effective therapies as an index treatment compared with moderately effective therapies with disease activity. 

The retrospective Observatoire Français dela Scléroseen Plaques cohort study was conducted from Jan. 1, 2010, to Dec. 8, 2022. The average follow-up was 5.8 years. A total of 36 French MS centers participated in the study. Of the total participants, only treatment-naive children with relapsing-remitting pediatric-onset MS who received an initial round of highly effective therapy or moderately effective therapy before adulthood, and at least one follow-up clinical visit, were included in the study.

The primary outcome was the time to first relapse after treatment. Secondary outcomes were annualized relapse rate, MRI activity, time to Expanded Disability Status Scale progression, tertiary education attainment, and treatment safety/tolerability.

In the 530 patients that were included in the study, both treatment strategies were linked to a reduced risk of first relapse within the first two years. Highly effective therapies dampened disease activity with a 54 percent reduction in first relapse risk sustained over five years, confirmed on MRI activity, and with a better tolerability pattern than moderately effective therapies. The risk of discontinuation at two years was six times higher with moderately effective therapies. The primary reasons for treatment discontinuation were lack of efficacy and intolerance. Index treatment was not linked to EDSS progression or tertiary education attainment. 

The findings suggest that compared with moderately effective therapies, initial highly effective therapies in pediatric onset MS were linked to a reduction in the risk of first relapse with an optimal outcome within the first two years; a lower rate of treatment switching; and a better midterm tolerance in children. The results suggest prioritizing initial highly effective therapies in pediatric onset MS, although long-term safety studies are needed.

The results were published in the journal JAMA Neurology.