In patients with relapsing multiple sclerosis (MS), daily treatment with a 75 mg dose of the BTK inhibitor evobrutinib reduces the total number of gadolinium-enhancing lesions on T1-weighted MRI, according to a randomized phase II trial. Montalban and colleagues randomly assigned 267 patients with MS to placebo, evobrutinib (25 mg once daily, 75 mg once daily or 75 mg twice daily) or open-label dimethyl fumarate (as a reference). Patients who received 75 mg evobrutinib once daily had significantly fewer gadolinium-enhancing lesions during weeks 12–24 than those who received placebo. The other doses had no significant effects on lesion numbers, and none of the doses reduced annualized relapse rates. In addition, evobrutinib treatment was associated with increased liver aminotransferase levels. The authors say that larger studies are needed to weigh up the risks and benefits of this drug.