Progressive multifocal leukoencephalopathy in anti-CD20 and other monoclonal antibody (mAb) therapies used in multiple sclerosis: A review

Progressive multifocal leukoencephalopathy (PML) is a subacute CNS inflammatory disease seen primarily among immunocompromised patients. It is caused by the JC virus (JCV), a polyomavirus that otherwise induces an insidious, latent infection in the general population. This reactivated disease is characterized by cognitive and behavioral changes, language disturbances, motor weakness, or visual deficits. Median survival in patients with AIDS is approximately 2-4months, and mortality is high (around 4% in untreated AIDS). Recent scientific developments indicate that PML can also be associated with the increased utilization of monoclonal antibody (mAb) immunotherapy. In fact, PML has been witnessed with several mAbs, including natalizumab in multiple sclerosis, rituximab for lymphoma or lupus, efalizumab for psoriasis, and ofatumumab in leukemia; this leads us to the risk reassessment of PML due to treatment-induced immunosuppression. The range of clinical presentations of JCV-related disease has transformed over time and can pose significant challenges to the current diagnostic criteria. Most cases with PML suffer from persistent and irreversible neurological conditions, and some with chronic, low-level viral replication in the CNS. With the expanded use of mAbs for various autoimmune and lymphoproliferative disorders, we are now seeing this infection in non-HIV patients on drugs such as natalizumab, rituximab, and other recently approved therapies. This article aims to review the relationship between the incidence of PML and ...