Real-world data from over 10 years in the TYSABRI® Observational Program: Long-term safety and effectiveness of natalizumab in relapsing-remitting multiple sclerosis patients

Introduction The TYSABRI Observational Program (TOP) began u003e 10 years ago to inform on long-term safety and effectiveness of natalizumab in relapsing-remitting multiple sclerosis (RRMS) patients in clinical practice. Objectives Report an interim analysis of safety and effectiveness in patients with up to 10 years of natalizumab treatment in TOP, an open-label, multinational, prospective, observational study. Patients and methods Annualised relapse rates (ARRs) for the year prior to starting natalizumab and on natalizumab (and ≤ 84 days post discontinuation) were compared using a repeated Poisson model. Confirmed Expanded Disability Status Scale (EDSS) worsening, and improvement, while on natalizumab were estimated by Kaplan–Meier analysis. Serious adverse events (SAEs) were assessed at clinical visits. Results As of November 2017, TOP included 6149 patients. ARR while on natalizumab was reduced by 89.4% (from 1.99 pre- natalizumab to 0.21 on natalizumab; P P P  .001), respectively. For those with 0, 1, or ≥ 2 prior DMTs, ARRs were reduced by 92.7% ( P P  P Discussion At 10 years, cumulative probabilities of 24-week–confirmed EDSS worsening and improvement were 32.9% and 35.5%, respectively. Overall, 828 of 6149 patients (13.5%) experienced ≥ 1 SAE (most commonly reported by system organ class: infections and infestations, 253 patients [4.1%]). Conclusion This analysis reinforces the consistent effectiveness—particularly when used earlier in the disease and treatment course–and the established safety profile of natalizumab, now assessed over 10 years.