Bruton's tyrosine kinase inhibitor for multiple sclerosis: new hope or false dawn

The first of several phase 3 trials examining efficacy in relapsing MS has not been able to demonstrate a significant benefit and has also raised important safety concerns. More results are on their way and it will be important to understand whether the safety signals identified are drug- or class-specific and whether other BTKi also fail to reach their endpoints for relapsing MS. However, as reported in preliminary data for another BTKi, it may be that they will have more of a role in progressive disease as hinted by the unraveling of relevant molecular mechanisms and pathways.