Progressive multifocal leukoencephalopathy (PML) is a serious viral infection associated with therapies for multiple sclerosis (MS) including sphingosine 1-phosphate (S1PR) receptor modulators.

A total of 24 cases of PML in MS patients treated with fingolimod were identified from 12 articles. Of these, 21 patients had data about changes in the expanded disability status scale (EDSS). One case of PML in association with treatment with ozanimod in a clinical trial was also identified. In PML cases associated with fingolimod, the mean age at the time of PML diagnosis was 50.91 ± 11.5 years with youngest 27 years to oldest 75 years old. All patients were treated with fingolimod for more than 24 months. Compared to patients who improved or were stable in terms of EDSS after symptomatic management of PML, the non-improving group were significantly older, but no difference was seen in gender distribution. The only management modality for PML which significantly differed between the two groups was mefloquine which was used more often in the non-improving group. There were no fatalities in either group during the reported follow-up period.