Natalizumab Discontinuation after the 24th Course: Which Is Way? The TY-STOP Study (P01.197)

OBJECTIVE: Comparison of disease activity (percentage of patients with relapses and/or MRI activity) between the year before and after Natalizumab discontinuation. BACKGROUND: Natalizumab may cause Progressive Multifocal Leucoencephalopathy (PML). According to risk stratification after the 24 th course, patients can decide whether to continue Natalizumab. DESIGN/METHODS: Multicenter prospective observational study, involving 7 centers, 88 patients enrolled (56 female; average age 40) with relapsing-remitting multiple sclerosis (RRMS) clinically and radiologically stable, treated with 24 Natalizumab administrations. The study provides 6 visits at month (M) 0, 1, 3, 6, 9, 12 and 3 brain MRI at M0, M6, M12. Enrolled patients reached the following timepoints: 80 patients M3, 68 patients M6, 55 patients M9, 31 patients M12. We calculated the percentage of relapses and MRI activity stratified by therapy. RESULTS: The percentage of patients with relapses during the year after Natalizumab discontinuation was 35.6%: 3.7% among patients continuing Natalizumab, 17.8% among those who started other immunomodulatory or immunosuppressive therapy and 16.7% among patients without therapy. The percentage of patients with MRI activity after 24 th Natalizumab course was 34.8%: 3.7% among patients continuing Natalizumab, 20.5% among those who started other immunomodulatory or immunosuppressive therapy and 21.4% among patients without therapy. Evaluation of HR with relative 95% CI for relapses, EDSS score > 3, MRI activity. Data show a protective effect of therapy with Natalizumab vs no therapy on MRI activity (HR 0.81; 95% CI 0.68-0.96; p=0.015).The average of relapses and MRI activity is similar in those patients who discontinued any therapy and in those who started a first line therapy. CONCLUSIONS: Our data show a protective effect of Natalizumab on MRI activity during the 12 months of follow-up. Considering the protective effect on MRI activity, Natalizumab should be continued over the 24 administrations according to the evaluation of patients9 risk to develop PML. Disclosure: Dr. Clerico has nothing to disclose. Dr. De Mercanti has nothing to disclose. Dr. Piazza has nothing to disclose. Dr. Gned has nothing to disclose. Dr. Brescia Morra has nothing to disclose. Dr. Lanzillo has nothing to disclose. Dr. Amato has nothing to disclose. Dr. Quarantelli has nothing to disclose. Dr. Ghezzi has received personal compensation for activities with Merck Serono, Teva Pharmaceutical Industries Ltd., Biogen Idec, Bayer Schering Pharma, Novartis, and Actelion Pharmaceu. Dr. Bianchi has nothing to disclose. Dr. Baroncini has nothing to disclose. Dr. Gibbin has nothing to disclose. Dr. Vargas has nothing to disclose. Dr. Salemi has received research support from Teva Pharmaceutical for a research project on oxidative stress factors and multiple sclerosis. Dr. Realmuto has nothing to disclose. Dr. Ferro has nothing to disclose. Dr. Vitetta has nothing to disclose. Dr. Sola has nothing to disclose. Dr Paolicelli has received personal compensation for activities with Merck, Serono, and Bayer Schering Pharma and has received speaker honoraria from Biogen Idec. Dr.Trojano has received personal compensation for activities with Sanofi-Aventis Pharmaceuticals, Inc., Biogen Idec, Novartis, and Bayer Schering. Dr. Trojano has received research supprot from Merck Serono, Biogen Idec, and Novartis. Dr. Durelli has received personal compensation for activities with Bayer, Genzyme Corporation, and Merck Serono.