Real-World Effectiveness and Safety after 5 Years of Dimethyl Fumarate Treatment in Black/African American and Hispanic/Latino American Patients with Multiple Sclerosis in Esteem

Background: Delayed-release dimethyl fumarate (DMF) has demonstrated efficacy and a stable benefit–risk profile in studies of patients with relapsing-remitting multiple sclerosis (RRMS). ESTEEM is an ongoing, phase 4, 5-year, observational study characterizing long-term effectiveness and safety of DMF in real-world clinical practice. Evidence suggests that MS clinical course and disability outcomes may vary according to ethnicity and race. DMF was efficacious in a small sample of Black/African American (AA) and Hispanic/Latino (H/L) patients in DEFINE/CONFIRM. A previous analysis of these subgroups in ESTEEM demonstrated effectiveness over 3 years of DMF treatment; however, longer-term data are limited.

Objectives: To evaluate real-world effectiveness and safety of DMF in Black/AA, non-Black/non-AA, H/L, and non-Hispanic/non-Latino (non-H/non-L) patients with RRMS.

Methods: ESTEEM included patients newly prescribed DMF in routine practice at ~390 sites globally. Effectiveness and safety of DMF were evaluated in a post hoc subgroup analysis in Black/AA, non-Black/non-AA, H/L, and non-H/non-L patients. Annualized relapse rates (ARR) were obtained by negative binomial model.

Results: Overall, 220 (4.2%) Black/AA, 5031 non-Black/non-AA, 105 (2.0%) H/L, and 5146 non-H/non-L patients received >1 dose of DMF and were included in the analysis, with follow-up over 60 months. Unadjusted ARRs (95% CI) up to 5 years were: Black/AA, 0.054 (0.038–0.078); non-Black/non-AA, 0.077 (0.072–0.081); H/L, 0.069 (0.043–0.112), and non-H/non-L,0.076 (0.072–0.081), representing reductions ranging from 90.6% to 92.1%, compared to ARR 12 months prior to study entry (P<0.0001 for all subgroups). Gastrointestinal disorders were the most common reason for discontinuation in both subgroups. In the first year, median lymphocyte counts declined 24.4% in Black/AA, 35.8% in non-Black/non-AA, 28.2% in H/L, and 35.6% in non-H/non-L patients, and then remained stable.

Conclusions: These data demonstrate real-world treatment benefit of DMF in Black/AA and H/L patients. Compared with the 12 months before DMF initiation, ARR was significantly lower up to 5 years after DMF initiation in Black/AA and H/L patients. DMF’s safety profile in these subgroups was consistent with the overall ESTEEM population, although lymphopenia was less pronounced in black/AA and H/L subgroups; these lymphocyte findings should be interpreted with caution as this study was not designed to compare lymphocyte changes between different patient subgroups.

Supported by: Biogen