Simultaneous Pml-Iris After Discontinuation of Natalizumab in A Patient With MS

Abstract

Gheuens et al.1 presented a case of progressive multifocal leukoencephalopathy–immune reconstitution inflammatory syndrome (PML-IRIS) 2 months after natalizumab discontinuation. Their patient had an active history of ethanol abuse, which can be considered a 'functional' equivalent to immunosuppression. Interestingly, prior use of immunosuppressants has been included in the recently developed risk-stratification algorithm for PML.2 This case underscores the need for clinicians to adopt a wider concept of immunosuppression, rather than restricting it solely to the use of pharmacologic agents. We and others published 3 cases of definitive severe multiple sclerosis (MS) rebound about 2 months following natalizumab discontinuation,3-5 and further implied that younger patients are more prone to such relapses.5 However, Gheuens et al. concluded that new enhancing MRI lesions after natalizumab withdrawal may also be the manifestation of PML-IRIS.1 As experience from patients discontinuing natalizumab and switching to other therapies mounts, a high degree of clinical vigilance for both incidences (i.e., MS rebound and PML) should follow the immediate post-natalizumab period. However, until official guidelines are issued, it is unclear exactly how patients should be treated in the interval between natalizumab and the next therapeutic choice.