BG-12 (dimethyl fumarate): a review of mechanism of action, efficacy, and safety

Background: Multiple sclerosis (MS) is a chronic inflammatory disease, affecting more than 2.5 million people worldwide with more 400,000 cases in the United States alone. There has been considerable improvement in the treatment of MS, with the introduction of disease-modifying drugs; however, new oral therapies may provide additional benefit by providing an alternative treatment modality and the potential for improved adherence by avoiding the injection-associated side effects and anxiety encountered with some first-line agents. BG-12 (dimethyl fumarate) is an oral agent approved in the United States for the treatment of relapsing forms of MS. Scope: We review published literature about what is known about the mechanism of action of BG-12, and key efficacy and safety findings from three clinical studies in patients with relapsing-remitting MS (RRMS). Findings: Data from preclinical studies have demonstrated that BG-12 may promote anti-inflammatory and cytoprotective activities that are mediated, at least in part, by the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) antioxidant response pathway. Studies in animals have shown a protective effect of BG-12 on neuronal, axonal and myelin integrity. Results from a phase 2 study and two randomized double-blind placebo-controlled phase 3 studies, CONFIRM and DEFINE, have shown that BG-12 provides clinical and radiologic efficacy in patients with RRMS. At 2 years, BG-12 240 mg twice and three times daily reduced annualized relapse rate (CONFIRM primary endpoint) by 44% and 51% and the risk of relapse (DEFINE primary endpoint) by 49% and 50%, respectively, compared with placebo (all p<0.001). BG-12 was generally well tolerated and had an acceptable safety profile, with a similar incidence of adverse events across treatment groups. Conclusions: BG-12 may have cytoprotective and anti-inflammatory properties that contribute to its efficacy among patients with RRMS. Findings from phase 2 and 3 studies further support BG-12 as an effective initial therapy.