Siponimod (BAF312) is a dual agonist at the sphingosine-1 phosphate receptors, S1PR1 and S1PR5. The S1P receptor is commonly found on the surface of specific cells residing in the central nervous system (CNS), that are responsible for causing CNS damage that drives loss of function in secondary progressive multiple sclerosis (SPMS). Siponimod (BAF312) enters the brain and by binding to these specific receptors, may prevent the activation of these harmful cells, helping to reduce the loss of physical and cognitive function associated with SPMS.