The Use of Natalizumab in Pediatric Patients With Active Relapsing Multiple Sclerosis: A Prospective Study.

Background: Pediatric multiple sclerosis (MS) has been increasingly recognized. In the absence of approved disease-modifying therapies (DMTs) for pediatric patients, clinicians resort to data extrapolated from clinical trials conducted in adults with MS. The objective of this article was to study the effectiveness and safety of natalizumab in with pediatric MS.

Methods: Patients with pediatric MS (aged less than 18 years) who had been treated with natalizumab were followed up prospectively as part of the national MS registry. Data of relapsing patients who had at least a one-year follow-up were analyzed. The primary outcome measure was the annual relapse rate after natalizumab treatment. Secondary outcomes measures included the mean change in disease progression measured by the expanded disability status scale and the proportion of patients with radiologic activity (gadolinium-enhancing or new T2 lesions) at the last follow-up visit.

Results: Thirty-two patients with pediatric MS had been treated with natalizumab for at least 12 months, of whom 72% were females. The mean age at onset and disease duration were 14.9 ± 2.6 and 5.1 ± 3.1 years, respectively. Most patients (n = 21, 66%) had breakthrough disease on first-line disease-modifying therapies. The mean number of natalizumab infusions was 34.5 ± 18. The annual relapse rate was significantly reduced (1.66 ± 0.5 vs 0.06 ± 0.25; P < 0.001), whereas the mean expanded disability status score improved (3.3 ± 1.3 vs 2.2 ± 1.0; P < 0.001) at the last follow-up visits. The proportion of patients with magnetic resonance imaging activity was significantly reduced (93.8% versus 12.5%; P < 0.001). No major adverse events were observed.

Conclusion: In our pediatric MS cohort with aggressive or breakthrough disease, treatment with natalizumab was effective in reducing clinical and radiologic disease activity. Natalizumab has a similar clinical efficacy and safety profile as in adult MS.