Substantial disease exacerbation in a patient with relapsing-remitting multiple sclerosis after withdrawal from siponimod.

Among patients with multiple sclerosis, discontinuing highly effective disease-modifying treatments can potentially lead to severe disease recurrence, especially cessation of natalizumab and fingolimod. Similar to fingolimod, siponimod is a sphingosine-1-phosphate receptor modulator that inhibits the egress of a lymphocyte subpopulation from lymph nodes. In the present case report, we describe a patient with MS who experienced substantial disease exacerbation after withdrawal from siponimod.