Abstract
Over the past 30 years increasing numbers of molecules have been developed for treatment of multiple sclerosis. However, given the heterogeneity of the disease and the fact that many patients have refractory or progressive multiple sclerosis, new therapeutic alternatives are still needed. Tyrosine kinases are enzymes that mediate phosphorylation of tyrosine residues on downstream molecules that participate in signalling pathways. These kinases have crucial roles in cellular proliferation and differentiation, cell growth and metabolism, and survival and apoptosis, making them potential therapeutic targets in various autoimmune and lymphoproliferative diseases. 1 , 2 Bruton’s tyrosine kinase is a cytoplasmic tyrosine kinase expressed by B cells and myeloid cells. 3 Both B cells and myeloid cells (particularly microglia) are important drivers of multiple sclerosis, 4 suggesting that inhibitors of Bruton’s tyrosine kinase, such as the irreversible inhibitors evobrutinib, tolebrutininb, and orelabrutinib, and the reversible inhibitors fenebrutinib and BIIB091, might provide therapeutic benefits for patients.