The natalizumab wearing-off effect End of natalizumab cycle, recurrence of MS symptoms

Objective Natalizumab is effective in treating relapsing-remitting multiple sclerosis (RRMS). However, many patients report an increase of multiple sclerosis symptoms at the end of the natalizumab cycle: a wearing-off effect. The objective of this study was to evaluate the prevalence of the wearing-off effect in patients with standard and extended intervals and to study possible associations with pharmacokinetic/dynamic measurements and patient characteristics in a prospective, monocenter, cross-sectional cohort study. Methods Patients with RRMS, with a minimum of 6 natalizumab infusions, were asked to complete 3 questionnaires: the Multiple Sclerosis Impact Scale, the 36-Item Short Form Health Survey, and a general questionnaire regarding the wearing-off effect. Natalizumab concentration and alpha 4-integrin receptor saturation were measured before redosing. Results Ninety-three patients were included. A total of 54% experienced a wearing-off effect during natalizumab treatment and 32% experienced a current wearing-off effect at time of measurement. The self-reported wearing-off effect was not associated with natalizumab concentration nor with alpha 4-integrin receptor saturation. The wearing-off effect was more frequently reported in the standard interval group (39%) than in the extended interval group (19%); the duration of symptoms was comparable between both groups. The wearing-off effect was not associated with number of infusions, disease duration, age, or sex. Conclusion The wearing-off effect is a frequently reported phenomenon but is unlikely to reflect a non-optimal pharmacokinetic/dynamic state. We did not find risk factors predicting the wearing-off effect.