Anti-John Cunningham virus antibody index levels in multiple sclerosis patients treated with rituximab, fingolimod, and dimethyl fumarate

Progressive multifocal leukoencephalopathy (PML), a potentially fatal demyelinating disease caused by the John Cunningham virus (JCV), can occur as a complication of treatment with rituximab, fingolimod, and dimethyl fumarate. The primary objective of this study was to determine changes in anti-JCV antibody index values in multiple sclerosis (MS) patients treated with these three medications. Second, we explored the relationship between absolute lymphocyte count (ALC), anti-JCV antibody index values, and various patient characteristics. In this retrospective chart review, we evaluated changes in JCV serology and ALC in 172 MS patients treated with fingolimod, rituximab, or dimethyl fumarate (2013-2016). Only those with known anti-JCV antibody and ALC values before starting the study medications were included. Subsequent values were obtained on an ad hoc basis throughout the study. There was a significant decrease in anti-JCV antibody index values in patients treated with fingolimod and rituximab ( = 0.03 and = 0.014, respectively). A non-significant decreasing trend in anti-JCV antibody index values occurred in patients treated with dimethyl fumarate. Notably, there was no relationship between ALC and anti-JCV antibody index values for patients treated with rituximab, fingolimod, or dimethyl fumarate. Anti-JCV antibody index values significantly decreased in MS patients treated with fingolimod and rituximab; however, this did not occur with dimethyl fumarate. Fingolimod and rituximab may impair the humoral response to the JCV. Nevertheless, a declining anti-JCV antibody index in MS patients treated with fingolimod or rituximab should not necessarily be interpreted as correlating with a decreased risk for PML.