Calabrese M, et al. – The efficacy of dimethyl fumarate (DMF) in preventing disease reactivation after natalizumab (NTZ) discontinuation was investigated in this study. DMF appeared generally safe and among investigated cases, no carry over progressive multifocal leukoencephalopathy (PML) was observed. DMF seemed anyway a promising drug for those patients who would discontinue NTZ although it did not eliminate the possibility of disease reactivation. The clinical and radiological activity preceding the DMF treatment could be used as a prognostic marker of therapy response.

• The physicians switched 39 patients with relapsing remitting multiple sclerosis, at high risk of PML, from NTZ to DMF and underwent neurological and 3T MRI monitoring for 2 years.
• They collected clinical and MRI data regarding the 2-year period preceding NTZ treatment, the 2 years of NTZ treatment and the 2 years of DMF.

• Among the 39 patients during the DMF phase, 1 or more relapses occurred in 5 patients (12.8%), increased disability progression in 4 (10.3%) and MRI activity in 8 (20.5%).
• Only in 1 patient, post-NTZ rebound effect was observed.
• They registered only 2 dropouts (1 rebound activity and 1 gastrointestinal side effect) and almost 80% of the patients did not report any evidence of disease activity at the end of DMF treatment.
• The multiple linear regression model demonstrated that the number of relapses and MRI parameters before DMF treatment were good predictors of disease activity during treatment with DMF.