Effect of natalizumab treatment on the rate of No Evidence of Disease Activity in young adults with multiple sclerosis in relation to pubertal stage.

Approximately 40% of young-onset multiple sclerosis (MS) patients experience breakthrough disease, which carries a high risk for long-term disability, and requires using therapies beyond traditional first-line agents. Despite the increasing use of newer disease-modifying treatments (DMTs) in this population, data are not available to guide the need for escalating DMTs and there is a scarcity of data on the effects of natalizumab in children and young adults with active disease. We performed a retrospective analysis of the rate of No Evidence of Disease Activity (NEDA), tolerability, and safety of natalizumab in a multi-center cohort of 36 children and young adults with highly active MS. All patients had active disease and initiated treatment with natalizumab. The primary endpoint was the rate of achieving NEDA-3 status, within two years of natalizumab treatment. To examine a possible effect of age on the outcome of treatment, outcomes were also analyzed by pre-pubertal (n = 13 children aged 9-13 years) and pubertal subgroups (n = 23 young adolescents aged 14-20 years). The NEDA-3 status of the pre-pubertal group was 92% in the first and second year and in the pubertal group - 96% in the first year and 92% in the second year. Natalizumab reduced the number and volume of brain lesions in both pre-pubertal and pubertal groups. Treatment was well-tolerated, only 8 patients (22.2%) had adverse events during the 2-year study period. Our analysis shows that natalizumab is effective and well-tolerated in pre-pubertal and pubertal MS patients.