Efficacy and tolerability of dimethyl fumarate in White-, African- and Hispanic- Americans with multiple sclerosis.

Background: Dimethyl fumarate (DMF) was approved by the US Food and Drug Administration (FDA) for treatment of relapsing-remitting multiple sclerosis (RRMS) based on two phase III randomized clinical trials (RCTs). There were not enough non-White patients enrolled in these RCTs to allow for subgroup analysis based on race. Efficacy and tolerability of DMF therapy across various racial groups is unknown.

Methods: Retrospective chart review was performed on all patients with RRMS who were started on DMF in two tertiary multiple sclerosis (MS) clinics. Efficacy and tolerability of DMF was compared across three self-identified racial groups: White-American (WA), African-American (AA) and Hispanic-American (HA).

Results: A total of 390 RRMS patients were included in the study: 261 (66.9%) WA, 69 (17.7%) AA and 52 (13.3%) HA. When comparing 'pre-DMF' (1 year) and 'on DMF' (mean follow up of 14 months) periods, statistically significant reduction in rates of annualized relapses (WA from 0.44 to 0.19, AA from 0.39 to 0.15, and HA from 0.39 to 0.14; no differences between groups), new T2 lesions (WA from 45% to 23%, AA from 39% to 23%, HA from 52% to 26%; no difference between groups), and Gd+ lesions (WA from 25% to 13%, AA from 24% to 7%, HA from 23% to 12%; no difference between groups) were seen. DMF was relatively well tolerated across all groups, with an overall discontinuation rate of 20% (no difference between the three groups).

Conclusion: Efficacy of DMF in our clinic population did not differ across three major ethnic groups, WA, AA and HA, and was comparable with results observed in the pivotal studies. These 'real-life' data suggest that race is not a factor that needs to be taken into account when initiating DMF.