Monomethyl fumarate has better gastrointestinal tolerability profile compared with dimethyl fumarate.

Background: Monomethyl fumarate (MMF) is the pharmacologically active metabolite of dimethyl fumarate (DMF). MMF formulated as Bafiertam™ 190 mg and DMF formulated as Tecfidera 240 mg deliver bioequivalent exposure of MMF and therefore possess the same efficacy/safety profiles. DMF is a widely used oral treatment for relapsing-remitting forms of multiple sclerosis (RRMS) but is limited in some patients, primarily female, by issues with gastrointestinal (GI) tolerability.

Methods: This was a randomized, double-blind, head-to-head, 5-week study evaluating the GI tolerability of MMF 190 mg vs DMF 240 mg, administered twice daily in healthy subjects, using a derivative of the self-administered Modified Overall Gastrointestinal Symptom Scale (MOGISS). Subjects were stratified (3:1, female:male) and randomized (1:1) to the treatments. The primary endpoint was the Area Under the Curve (AUC) in each of the individual symptoms in the MOGISS over the 5-week treatment period. Other endpoints included the AUC over the 5-week treatment period in the MOGISS composite and total scores; duration and severity of GI events; Number and percentage of subjects reporting GI events during the overall treatment period, and assessment of safety/tolerability.

Results: Inferential analysis of the hierarchical testing of overall treatment differences in each MOGISS symptom AUC occurred in a predefined sequence starting with Abdominal Pain. For each symptom, LSMean AUC values were lower for MMF than DMF, however, the first primary endpoint, Abdominal Pain, was not statistically different between treatments; thus, all subsequent statistical analyses were considered exploratory. The side effects and safety profiles observed were consistent with the known profiles of DMF, with no new or unique safety concerns noted.

Conclusions: Bafiertam showed an improved gastrointestinal tolerability profile compared with Tecfidera, with less severe GI events and fewer days of self-assessed GI symptoms, fewer GI adverse events, and lower discontinuation rates because of GI adverse events.