Do CCR5 antagonists improve the overall survival of patients with AIDS-related progressive multifocal leucoencephalopathy?

Progressive multifocal leucoencephalopathy (PML), a devastating demyelinating disease caused by John Cunningham virus (JCV) reactivation, affects patients with severe immune deficiencies.1 Despite having tested numerous molecules over the last 25 years, their benefits have often been overstated based on isolated case reports or small series.1 Because those therapies offered patients with PML some, although limited, hope, the desire to try an inaccurately tested but potentially lifesaving treatment surpasses rigorous clinical trial evaluation before widespread use. Notably, cidofovir’s alleged promise, based on case reports, largely evaporated when prospective cohort studies demonstrated that it had no influence on AIDS-related PML (AR-PML) overall survival (OS) or residual disability.2 That story might be repeating itself with maraviroc (MVC) use, also based on only a few favourable case reports.3 Restoring JCV-specific immune responses is the most effective way to improve survival of patients with PML.1 Immune recovery is not always beneficial and a subset of patients with PML may worsen due to immune reconstitution inflammatory syndrome (PML-IRIS), mediated by CD8+ T cells strongly expressing CC chemokine receptor-5 (CCR5). MVC is a non-competitive CCR5 antagonist approved in the HIV armamentarium. Histological findings and some case reports inferred that MVC might work as a mediating double-edged sword by enhancing CD4+ T-cell reconstitution and its potential immunomodulatory properties to improve AR-PML and AR-PML-IRIS survival in various conditions (idiopathic CD4+ T-cell lymphocytopaenia, sarcoidosis and natalizumab-treated patients with multiple sclerosis).4 But, MVC had no beneficial effect on OS of patients with PML in one-third of reports (online supplementary …