A phase II trial of the sphingosine 1-phosphate 1 receptor modulator amiselimod has indicated that the drug is effective and safe in patients with relapsing–remitting multiple sclerosis. 415 patients were randomly assigned to receive 0.1 mg, 0.2 mg or 0.4 mg amiselimod or a placebo. The median total number of gadolinium-enhanced T1-weighted lesions during a 24-week treatment period was lower among patients who received 0.2 mg or 0.4 mg amiselimod than among those who received 0.1 mg or placebo. No serious adverse events were reported.