Patient enrollment of phase III tolebrutinib trials for multiple sclerosis + myasthenia gravis paused in the U.S. -Sanofi

The FDA action was based on a limited number of cases of drug-induced liver injury that have been identified with tolebrutinib exposure in Phase III studies. The majority of the impacted patients were determined to have concurrent complications known historically to predispose to drug-induced liver injury. Importantly, the elevations of laboratory values used for monitoring liver injury were reversible after drug discontinuation for all cases. Following earlier dialog with FDA about these cases, study protocols were revised in May 2022 to update the monitoring frequency, and enrollment criteria were revised to exclude preexisting risk factors for hepatic dysfunction.

Enrollment in the clinical program continues with the revised study protocols and enhanced safety monitoring in countries outside of the U.S. Sanofi is working closely with the independent data monitoring committee members and investigators around the world to evaluate the effectiveness of safety measures. The program in MS has been enrolling patients since 2019 and includes more than two-thousand patients currently on tolebrutinib therapy with durations of treatment as long as three years.