Dimethyl fumarate treatment in multiple sclerosis: Recent advances in clinical and immunological studies

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system (CNS) in which demyelination and neurodegeneration occurs. The immune system of MS patients is characterized by a dysregulation in the balance between pro- and anti-inflammatory immune cells, whereby both the innate and adaptive immune system are involved. Dimethyl fumarate (DMF) was licensed in 2013 as an oral first-line therapy for relapsing-remitting (RR)MS patients. It has a strong efficacy with neuroprotective and immunomodulatory effects and a favourable benefit-risk profile. However, the effects of DMF on the immune system of MS patients were not clear before entering the market. During the last years, numerous in vitro and ex vivo studies have clarified the working mechanism of DMF in MS. Here, we discuss the pharmacokinetics of DMF and its effect on molecular immune-related pathways, which is further linked to the clinical and immunological effects of DMF treatment. The efficacy and safety of DMF treatment for RRMS is discussed as reported from clinical trials. Further, the immunological effects of DMF treatment in RRMS patients are addressed in more detail, including the distribution and function of immune cells. Taken together, evidence from recent studies points to a multifactorial working mechanism of DMF treatment in MS which leads to a restored immune balance favouring a more tolerogenic or anti-inflammatory immune profile.