Efficacy and safety of dimethyl fumarate in treatment-naïve Japanese patients with multiple sclerosis: Interim analysis of the randomized placebo-controlled study

Background The use of dimethyl fumarate has not been reported in treatment-naïve Japanese patients with relapsing–remitting multiple sclerosis. Objectives The purpose of this study was to evaluate the efficacy and safety of dimethyl fumarate in treatment-naïve Japanese patients with relapsing–remitting multiple sclerosis. Methods APEX was a phase 3, multinational trial, which consisted of a 24-week, randomized (1:1), double-blind study where patients received dimethyl fumarate 240 mg or placebo twice daily, followed by an open-label extension where all patients received dimethyl fumarate 240 mg. The primary endpoints were the total number of new gadolinium-enhancing (Gd+) lesions in Weeks 12–24 (Part I) and long-term safety (Part II). This post-hoc subgroup analysis evaluated the efficacy and safety of dimethyl fumarate in treatment-naïve Japanese patients with relapsing–remitting multiple sclerosis ( n=52) up to Week 72 (24 weeks Part I and 48 weeks Part II). Results Dimethyl fumarate reduced the mean total number of new gadolinium-enhancing lesions at Weeks 12–24 by 94% versus placebo; the number of patients who had a relapse over 24 weeks was reduced by 72%. Adverse events leading to discontinuation of the study drug were reported in 9% of patients receiving placebo/dimethyl fumarate and 4% of patients in dimethyl fumarate/dimethyl fumarate. Conclusions Dimethyl fumarate demonstrated sustained efficacy and acceptable tolerability in treatment-naïve Japanese patients with relapsing–remitting multiple sclerosis for 72 weeks.