Switching from natalizumab to fingolimod: an observational study.

BACKGROUND Multiple sclerosis patients who discontinue using natalizumab are at risk of a rebound in disease activity. However, the optimal alternative therapy is not currently known. AIMS OF THE STUDY We report on clinical and MRI data and patient safety in a group of relapsing-remitting multiple sclerosis patients who tested seropositive for the JC virus and who have switched from natalizumab to fingolimod because of concerns regarding PML risks. METHODS The test for JC virus antibodies was performed in 18 relapsing-remitting multiple sclerosis patients who were being treated with natalizumab for more than 1 year. Eight seropositive patients switched to fingolimod while the seronegative patients continued with natalizumab. RESULTS After switching to fingolimod, five of eight patients (63%) experienced clinical relapses, and MRI activity was detected in six of eight patients (75%). Neither clinical relapses nor MRI activity was observed in the patients who continued with natalizumab. No serious adverse effects were detected. CONCLUSIONS Natalizumab is an effective treatment for relapsing-remitting multiple sclerosis, but its discontinuation continues to be a complex problem. All of the therapies tried thus far, including fingolimod, have been unable to control the reactivation of the disease. Further studies addressing alternative therapies after natalizumab discontinuation are necessary.