JC Virus Reactivation with Natalizumab

A preliminary study shows that JC virus reactivation is common during natalizumab therapy.

Natalizumab, an adhesion-molecule inhibitor, clearly increases the risk for progressive multifocal leukoencephalopathy (PML) associated with JC virus. Natalizumab-associated PML has occurred in patients with multiple sclerosis (MS) and Crohn disease, two conditions not previously associated with the disorder. The precise mechanism or mechanisms by which natalizumab predisposes to PML remain unknown. To identify possible predisposing factors, researchers used quantitative polymerase chain reaction (PCR) on urine, plasma, and peripheral blood mononuclear cell (PBMC) samples prospectively collected from 19 patients with MS before and during 18 months of natalizumab monotherapy.

At baseline, JC virus was not detected in plasma and PBMCs and was …

Reviewing Author

Joseph R. Berger, MD