Risk of Progressive Multifocal Leukoencephalopathy Among Patients With Multiple Sclerosis Exposed to Zeposia

This study will evaluate the risk of progressive multifocal leukoencephalopathy (PML), a rare brain infection caused by John Cunningham virus (JCV), among people with multiple sclerosis who have been treated with ozanimod. The study will collect and review reported cases of PML to describe patient characteristics and estimate how often PML occurs among people treated with ozanimod. Researchers will assess factors that may be associated with the occurrence of PML, such as age, duration of ozanimod exposure, prior immunosuppressant use, lymphopenia, and JCV antibody status .

Inclusion Criteria: * Adverse event (AE) report with MedDRA Preferred Term of " John Cunningham virus (JCV) cerebrospinal fluid test positive", " JCV granule cell neuronopathy", or "Progressive multifocal leukoencephalopathy (PML)" reported to the Sponsor between 4-Jun-2026 and 31-Jul-2041. * AE report(s) originating from spontaneous post-marketing reports, post-marketing observational studies with primary data collection, or patient support programs. * Diagnosis of multiple sclerosis before the initial AE report. * Exposure to at least one dose of ozanimod before onset of PML symptoms. * PML event assessed as "definite" or "probable" by the adjudication committee. * PML assessed as "related" to ozanimod by the adjudication committee. Exclusion Criteria: • There are no additional exclusion criteria.