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.