Natalizumab may be an effective and well tolerated second-line treatment for pediatric patients with highly active relapsing-remitting multiple sclerosis (MS), say researchers.
In a cohort of 20 patients (mean age 16.7 years) who had an insufficient response to first-line therapy, disease activity was strongly repressed after starting natalizumab.
As reported in JAMA Neurology, the patients had significant reductions in annual relapse rates, Expanded Disability Status Scale (EDSS) scores, and numbers of new T2 lesions during treatment.
"Natalizumab is one of the most effective drugs when used to treat MS in adults who have had an insufficient response to first-line therapy but it is not yet approved for use in pediatric patients with the disease," explain Barbara Kornek (Medical University of Vienna, Austria) and colleagues.
In the current study, 14 (70%) patients remained relapse free after monthly treatment with natalizumab 300 mg over a mean treatment period of 20 months. Ten (67%) of 15 patients who received treatment for 1 year and four (57%) of seven treated for 2 years remained relapse-free.
For 18 patients, the annualized relapse rate was significantly lower during therapy than before therapy, with a mean reduction in relapse events of 3.4 per year.
In addition, all 20 patients had significant improvements in EDSS scores, 13 had a significant decrease in the number of gadolinium-enhancing lesions, and 10 had a significantly decreased number of new T2 lesions per year.
Of 13 patients tested for John Cunningham virus (JCV) antibodies, five were found to be seropositive, leading to discontinuation of treatment for three of these patients at 3.5, 1.8, and 3.5 years.
Eight patients had discontinued therapy before the last follow up (42 months) due to complications including anaphylactic reaction associated with high-titer neutralizing antibodies, the presence of JCV antibodies, or severe asthenia. Six of these patients experienced one or more relapse within 6 months of discontinuing the therapy.
Use of natalizumab needs to be strictly indicated because of the associated risk with JCV - induced progressive multifocal leukoencephalopathy, a risk which seems to increase with age and duration of treatment. However, a recent consensus statement of the International Pediatric Multiple Sclerosis Study Group recommends that treatment options for pediatric patients should include natalizumab.
"Our data indicate that natalizumab may be safe and effective against MS in pediatric patients with breakthrough disease," say Kornek et al. "Our study underlines the need for controlled studies on the use of natalizumab and other second-line agents for children and adolescents with breakthrough disease."
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