Treatments of paediatric multiple sclerosis: Efficacy and tolerance in a longitudinal follow-up study

Pediatric-onset Multiple Sclerosis treatment: a multicentre observational study comparing natalizumab with fingolimod

BACKGROUND

Pediatric-onset Multiple Sclerosis (POMS) patients show more inflammatory disease compared with adult-onset MS. However, highly effective treatments are limited with only fingolimod being approved in Italy and natalizumab prescribed as off-label treatment.

OBJECTIVES

to compare the efficacy of natalizumab versus fingolimod in POMS.

METHODS

This is an observational longitudinal multicentre study including natalizumab- and fingolimod-treated POMS patients (N-POMS and F-POMS, respectively). We collected Annual Relapse Rate (ARR), Expanded Disability Status Scale (EDSS), Symbol Digit Modality Test (SDMT), and MRI activity at baseline (T0), 12-18 months (T1), and last available observation (T2).

RESULTS

We enrolled 57 N-POMS and 27 F-POMS patients from six Italian MS Centres. At T0, N-POMS patients showed higher ARR (p = 0.03), higher EDSS (p = 0.003) and lower SDMT (p = 0.04) at baseline compared with F-POMS. Between T0 and T1 ARR improved for both N-POMS and F-POMS (p < 0.001), while EDSS (p < 0.001) and SDMT (p = 0.03) improved only for N-POMS. At T2 (66.1 ± 55.4 months) we collected data from 42 out of 57 N-POMS patients showing no further ARR decrease.

CONCLUSION

Both natalizumab and fingolimod showed high and sustained efficacy in controlling relapses and natalizumab also associated to a disability decrease in POMS. This latter effect might be partly mediated by the high inflammatory activity at baseline in N-POMS.

Old and New Strategies in the Treatment of Pediatric Multiple Sclerosis: A Personal View for a New Treatment Approach

Up to 10 years ago the most common approach to the treatment of pediatric MS (ped-MS) was to start with IFNB or GA (so-called first-line therapies or moderate-efficacy disease-modifying therapies [ME-DMTs]) and to switch to more aggressive treatments (or high-efficacy disease-modifying therapies [HE-DMTs]) in non-responder patients. The use of HE-DMTs as first choice was recommended in selected cases with an active, aggressive form of MS. Indications for the treatment of ped-MS were essentially derived from data of observational studies. Recently, results of three randomized clinical trials have been published as well as data from many observational studies evaluating the effect of new and more active DMTs, with clear evidence that HE-DMTs are more effective than ME-DMTs. Therefore, the paradigm of treatment for patients with MS onset before 18 years of age should be changed, offering treatment with HE-DMTs as first option, because of their superior effectiveness to prevent relapses and disease progression. HE-DMTs present an overall reassuring safety profile and obtain better adherence to treatment.

Highly Effective Therapies as First-Line Treatment for Pediatric-Onset Multiple Sclerosis

Importance

Moderately effective therapies (METs) have been the main treatment in pediatric-onset multiple sclerosis (POMS) for years. Despite the expanding use of highly effective therapies (HETs), treatment strategies for POMS still lack consensus.

Objective

To assess the real-world association of HET as an index treatment compared with MET with disease activity.

Design, Setting, and Participants

This was a retrospective cohort study conducted from January 1, 2010, to December 8, 2022, until the last recorded visit. The median follow-up was 5.8 years. A total of 36 French MS centers participated in the Observatoire Français de la Sclérose en Plaques (OFSEP) cohort. Of the total participants in OFSEP, only treatment-naive children with relapsing-remitting POMS who received a first HET or MET before adulthood and at least 1 follow-up clinical visit were included in the study. All eligible participants were included in the study, and none declined to participate.

Exposure

HET or MET at treatment initiation.

Main Outcomes and Measures

The primary outcome was the time to first relapse after treatment. Secondary outcomes were annualized relapse rate (ARR), magnetic resonance imaging (MRI) activity, time to Expanded Disability Status Scale (EDSS) progression, tertiary education attainment, and treatment safety/tolerability. An adapted statistical method was used to model the logarithm of event rate by penalized splines of time, allowing adjustment for effects of covariates that is sensitive to nonlinearity and interactions.

Results

Of the 3841 children (5.2% of 74 367 total participants in OFSEP), 530 patients (mean [SD] age, 16.0 [1.8] years; 364 female [68.7%]) were included in the study. In study patients, both treatment strategies were associated with a reduced risk of first relapse within the first 2 years. HET dampened disease activity with a 54% reduction in first relapse risk (adjusted hazard ratio [HR], 0.46; 95% CI, 0.31-0.67; P < .001) sustained over 5 years, confirmed on MRI activity (adjusted odds ratio [OR], 0.34; 95% CI, 0.18-0.66; P = .001), and with a better tolerability pattern than MET. The risk of discontinuation at 2 years was 6 times higher with MET (HR, 5.97; 95% CI, 2.92-12.20). The primary reasons for treatment discontinuation were lack of efficacy and intolerance. Index treatment was not associated with EDSS progression or tertiary education attainment (adjusted OR, 0.51; 95% CI, 0.24-1.10; P = .09).

Conclusions and Relevance

Results of this cohort study suggest that compared with MET, initial HET in POMS was associated with a reduction in the risk of first relapse with an optimal outcome within the first 2 years and was associated with a lower rate of treatment switching and a better midterm tolerance in children. These findings suggest prioritizing initial HET in POMS, although long-term safety studies are needed.