Tolebrutinib in Nonrelapsing Secondary Progressive Multiple Sclerosis

Throughout the course of multiple sclerosis, gradually progressive neurologic impairment can occur, which has been called disability accrual. Current disease-modifying therapies for multiple sclerosis have limited effects on disability accrual unrelated to relapses, which is thought to be partially caused by chronic, nonresolving neuroinflammation within the central nervous system. Tolebrutinib is an oral, brain-penetrant Bruton's tyrosine kinase inhibitor that targets myeloid cells (including microglia) and B cells in both the periphery and central nervous system. There are no approved treatments for nonrelapsing secondary progressive multiple sclerosis.

In a phase 3, double-blind, placebo-controlled, event-driven trial, we randomly assigned participants with nonrelapsing secondary progressive multiple sclerosis, in a 2:1 ratio, to receive tolebrutinib (60 mg once daily) or matching placebo. The primary end point was confirmed disability progression that was sustained for at least 6 months, assessed in a time-to-event analysis.