Real-World Safety and Effectiveness After 5 Years of Dimethyl Fumarate Treatment in Black and Hispanic Patients with Multiple Sclerosis in ESTEEM.

INTRODUCTION: Multiple sclerosis (MS) clinical trials have included low numbers of patients from racial and ethnic minority populations; therefore, it is uncertain whether differences exist in response to disease-modifying therapies. We evaluated the real-world safety and effectiveness of dimethyl fumarate (DMF) treatment over 5 years in four patient cohorts: Black, non-Black, Hispanic, and non-Hispanic people with relapsing-remitting MS. METHODS: ESTEEM is an ongoing, 5-year, multinational, prospective study evaluating the long-term safety and effectiveness of DMF in people with MS. The analysis included patients newly prescribed DMF in routine practice at 393 sites globally. RESULTS: Overall, 5251 patients were analyzed (220 Black, 5031 non-Black; 105 Hispanic, 5146 non-Hispanic). Median (min-max) months of follow-up was 32 (0-72) for Black, 29 (1-77) for Hispanic, and 41 (0-85) for both the non-Black and non-Hispanic populations. In total, 39 (18%) Black and 29 (28%) Hispanic patients reported adverse events leading to treatment discontinuation versus 1126 (22%) non-Black and 1136 (22%) non-Hispanic patients; gastrointestinal disorders were the most common in all subgroups. Median lymphocyte counts decreased by 37% in Black, 40% in non-Black, 10% in Hispanic, and 39% in non-Hispanic patients in the first year, then remained stable and above the lower limit of normal in most patients. Annualized relapse rates (ARRs) (95% confidence intervals) up to 5 years were 0.054 (0.038-0.078) for Black, 0.077 (0.072-0.081) for non-Black, 0.069 (0.043-0.112) for Hispanic, and 0.076 (0.072-0.081) for non-Hispanic populations, representing reductions of 91-92% compared with ARR 12 months before study entry (all p < 0.0001). CONCLUSION: The safety profile of DMF in these subgroups was consistent with the overall ESTEEM population. Relapse rates remained low in Black and Hispanic patients, and consistent with non-Black and non-Hispanic patients. These data demonstrate a comparable real-world treatment benefit of DMF in Black and Hispanic patients. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT02047097.