Switching from Tysabri increases risk of relapsePublished: 18 June 2020 A new study has found the risk of a relapse for someone with relapsing remitting multiple sclerosis (RRMS) switching from Tysabri (natalizumab) to another injectable or oral after two or more years on the therapy is two to three times higher than if they continued on Tysabri. The drug is an antibody-based injection therapy that prevents immune cells from entering the brain. Studies show it is very effective at treating MS, but it increases the risk of progressive multifocal leukoencephalopathy (PML), which is a rare brain infection caused by the John Cunningham virus. Doctors will often look to switch patients to another drug as long-term use (more than two years) of Tysabri is linked to an increased risk of PML. The researchers say the study highlights how important it is to assess the risk of PML and the risk of a return of disease activity before making any decisions about switching treatment. Other Stories You May Be Interested In... News Oxygen depravation eases MS in study View article News UK MS diagnosis rate stays constant for 20 years with MS patients LESS likely to have other autoimmune conditions View article News Targeted nanocapsules offer hope for MS treatment in new study View article