This orally administered Bruton's tyrosine kinase inhibitor, which crosses the blood-brain barrier, failed to delay the time to confirmed composite disability progression at 6 months compared to placebo.

Preliminary analysis showed that the safety profile was consistent with previous studies of tolebrutinib. Full safety and efficacy results will be presented at an upcoming medical conference.

Based on these results, Sanofi will not pursue regulatory registration for primary progressive multiple sclerosis, a form that accounts for 10% of the overall MS patient population.

Sanofi will perform an impairment test on the value of the intangible asset attached to tolebrutinib, the status of which will be communicated with the results for fiscal year 2025, for which the financial outlook remains unchanged.