India Pharma Outlook Team | Tuesday, 16 December 2025
Sanofi said today that tolebrutinib failed to meet its primary endpoint in the PERSEUS phase 3 study in people with primary progressive multiple sclerosis (PPMS), a form of the disease that affects about 10% of the overall MS population.
The study did not show a delay in time to six-month composite confirmed disability progression (cCDP), leading the company to stop plans for regulatory filing in PPMS.
“We are disappointed by today’s results; however, we do believe that these results will improve our understanding of the underlying disease biology of multiple sclerosis,” said Houman Ashrafian, executive vice president, head of research & development at Sanofi. “We extend our deepest appreciation to the study participants, their families, and healthcare professionals who support … non-relapsing secondary progressive multiple sclerosis.”
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Sanofi said preliminary findings showed the safety profile of tolebrutinib was consistent with earlier studies. Drug-induced liver injury remains an identified risk, and the company emphasized strict liver monitoring and rapid management of enzyme elevations. Full safety and efficacy data will be shared at a future medical meeting.
Despite the PPMS setback, tolebrutinib remains provisionally approved in the United Arab Emirates for non-relapsing secondary progressive multiple sclerosis and is under regulatory review in the EU and other regions. The drug received FDA breakthrough therapy designation in December 2024.
Sanofi will conduct an impairment test under IFRS on the asset value tied to tolebrutinib, with results expected alongside Q4 and full-year 2025 earnings in January 2026. The company said this will not affect net income, earnings per share, or its 2025 financial guidance.
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