Characterizing the Natalizumab “Wearing Off” Effect: Tysabri WOEs

Background: Multiple Sclerosis patients treated with Natalizumab often report a “wearing-off effect”, described as worsening MS symptoms or various constitutional symptoms, most often prior to their next dose.

Objectives: We sought to better characterize the "wearing-off" phenomenon in our patient population and compare the intensity, onsent, and duration of symptoms in patients on a four-week dosing cycle to those on a six- or eight-week dosing cycle. 

Methods: We performed a prospective observational study on all of our MS patients being treated with Natalizumab for 3 months or longer, using a questionnaire to evaluate the prevalence and severity of constitutional symptoms, and temporal relationship to their dose. 

Results: 83 patients were surveyed. 63% of patients noted symptoms prior to their dose of Natalizumab, the most prominent being fatigue. The majority experienced symptoms 4-9 days prior to each dose, regardless of the dosing interval. Symptoms typically resolved within one day of their infusion. 

Conclusions: Our data suggests approximately two-thirds of patients experience the “wearing-off effect” predominately characterized by fatigue and myalgias. Additionally, there was no significant difference in intensity, onset, or duration of symptoms in patients on a four-week dosing cycle compared to those on a six- or eight-week dosing cycle, suggesting patients acclimate to their prescribed dosing cycle.