Overview
- The PERSEUS Phase 3 trial in primary progressive MS did not meet its primary endpoint of delaying six‑month composite confirmed disability progression.
- Following the failure, Sanofi will not seek regulatory registration for tolebrutinib in primary progressive MS.
- The FDA pushed the U.S. review for non‑relapsing secondary progressive MS from December 28, 2025 to the end of Q1 2026, and the company submitted an expanded access protocol at the agency’s request.
- Development continues in non‑relapsing secondary progressive MS, where the drug holds provisional approval in the UAE and remains under review in the European Union.
- Sanofi will conduct an impairment test on tolebrutinib‑related intangibles and says 2025 guidance is unchanged, while safety findings were consistent with prior studies and require strict liver monitoring.