A Phase 2 Study of Tolebrutinib in Relapsing Multiple Sclerosis

Existing disease-modifying treatments for multiple sclerosis (MS) affect lymphocytes but have limited activity on microglia. Tolebrutinib is an investigational (not FDA-approved) drug that inhibits Bruton's tyrosine kinase (BTK), downregulating B lymphocytes and myeloid cells. This manufacturer-funded, phase 2, 16-week, randomized, double-blind, dose-finding trial evaluated 4 different tolebrutinib dose groups in 130 participants with active (relapsing) multiple sclerosis.

With the highest (60-mg) dose, the primary outcome of new contrast-enhancing brain lesions on MRI at week 12 compared with 4 weeks previously was 0.13 per patient, compared with 1.03 per patient with placebo. The medication was well tolerated. The most common adverse event…