Sanofi says tolebrutinib did not meet primary endpoint in PERSEUS phase 3 study

Sanofi (SNY) announced that results from the PERSEUS phase 3 study showed that tolebrutinib did not meet its primary endpoint in delaying time to 6-month composite confirmed disability progression in participants with primary progressive multiple sclerosis , which represents 10% of the overall multiple sclerosis patient population. Based on these results, Sanofi will not pursue regulatory registration for PPMS. Preliminary analysis showed the safety profile was consistent with previous tolebrutinib studies. As previously reported, drug-induced liver injury is an identified risk of tolebrutinib. Strict adherence to liver monitoring requirements, and prompt management of liver enzyme elevations, are important to mitigate DILI risk. Full safety and efficacy results will be presented at a forthcoming medical meeting. Tolebrutinib was provisionally approved in the United Arab Emirates in July 2025 for the treatment of non-relapsing secondary progressive multiple sclerosis and to slow disability accumulation independent of relapse activity in adults. It is currently under regulatory review in the EU and other jurisdictions worldwide. Tolebrutinib was previously granted breakthrough therapy designation by the FDA in December 2024. Sanofi will conduct an impairment test in accordance with IFRS on the intangible asset value attached to tolebrutinib with a status to be provided with Q4 and FY 2025 results in January 2026. The outcome of this test will have no impact to the business net income / business EPS and there is no change to the financial guidance for 2025.