Switching from Tysabri increases risk of relapse

Published: 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.