Elevation of serum neurofilament light-chain levels disclose possible occult progressive multifocal leukoencephalopathy and immune reconstitution syndrome in a patient receiving ozanimod: a case report.

BACKGROUND

We report the first case of findings suggestive of progressive multifocal leukoencephalopathy and immune restitution syndrome (PML-IRIS) in a patient with multiple sclerosis receiving ozanimod preceded by an unexpected increase in the serum neurofilament light-chain (sNfL) levels.

CASE REPORT: A 57-year-old-woman treated with ozanimod for the last 8 years presented, during surveillance MRI, with findings compatible with PML-IRIS. Overt clinical symptoms were absent. sNfL levels increased 4 months earlier and peaked at presentation. Lymphocyte count reached nadir of 330/mL at 8 months earlier.

CONCLUSION

The case illustrates the utility of sNfL levels for PML surveillance in patients receiving immunosuppressors.