Dimethyl fumarate (DMF) is a novel oral therapy that has recently been approved for the treatment of relapsing-remitting multiple sclerosis (RRMS). Dimethyl fumarate shows anti-inflammatory and cytoprotective properties that are thought to be mediated primarily via activation of the nuclear factor (erythroid-derived 2)-like 2 - Nrf2 transcriptional pathway, which up-regulates the genes involved in the cellular response to oxidative stress. The drug was evaluated in 2 large, randomized, double-blind, multicentric, multinational, 2-year, phase III clinical trials. The DEFINE and CONFIRM trials, conducted with over 2600 adult patients suffering from RRMS, unequivocally confirmed the efficacy of DMF (2x240 mg daily) in reducing the annualized relapse rate (ARR) and reducing the proportion of patients with MS relapse at 2 years. Significantly reduced sustained disability progression was observed with the drug versus placebo in DEFINE, while the same tendency was seen in CONFIRM. The MRI results of the studies were also convincing: DMF significantly reduced the number of new/enlarging T2-hyperintense lesions and the number of Gd-enhancing lesions compared to placebo. Dimethyl fumarate was generally well tolerated and no safety concern has been raised. Adverse events that occurred most frequently included flushing and gastrointestinal events. The long- term efficacy and tolerability of dimethyl fumarate is currently being investigated in the ENDORSE trial, with interim results demonstrating the same results as the two previous studies. In conclusion, although further, mostly comparative data are needed to fully establish the relative efficacy and tolerability of dimethyl fumarate compared with other therapies, dimethyl-fumarate is a valuable addition to the therapeutic options available for RRMS.
