Disease Exacerbation after the Cessation of Fingolimod Treatment in Japanese Patients with Multiple Sclerosis

Objective In Japan, following the launch of dimethyl fumarate (DMF) after fingolimod as a diseasemodifying drug in multiple sclerosis (MS), some patients switched from fingolimod to DMF. The aim of this study was to determine the follow-up status of MS patients who switched to DMF after fingolimod cessation. Methods Clinical and magnetic resonance imaging (MRI) data in 19 patients with MS who switched to DMF were collected for at least for 6 months after fingolimod cessation. Results Ten patients (52.6%) experienced clinical or MRI exacerbation after fingolimod cessation. The peripheral blood lymphocyte counts at the time of fingolimod cessation in those with disease exacerbation were significantly lower than in those without exacerbation. The patients with disease exacerbation were further classified into three groups based on MRI findings: those with some new T2-weighted lesions with or without gadolinium (Gd) enhancement (group I), those with more new and/or enlarged T2-weighted lesions with Gd enhancement compared to pre-fingolimod induction (group II), and those with multifocal tumefactive demyelinating lesions. In group II, the clinical disease activity, which was similar to that at fingolimod initiation in group I, was higher than the clinical disease activity observed before fingolimod initiation. Conversely, group III exhibited unexpected new MRI findings that were not evident before fingolimod initiation. Conclusion Cessation of fingolimod might precipitate rebound or reactivation of clinical disease in patients with MS, and careful follow-up is necessary for patients who discontinue fingolimod.