Annals of the rheumatic diseases
-
Current data suggest that as many as 1 in 1000 treated individuals may develop progressive multifocal leucoencephalopathy (PML) in concert with the use of natalizumab. Natalizumab was withdrawn in early 2005. ⋯ It is likely that use of drugs which cause specific perturbations of the immune system will be accompanied by similar rare infections. Thus researchers should be on the alert when using such agents in clinical trials.