Sanofi Stock (SAN.PA, SNY) Slides After Tolebrutinib Double Setback: FDA Delay, Trial Miss, and Fresh Analyst Forecasts (Dec. 15, 2025)
Sanofi stock is under pressure on December 15, 2025, after the French drugmaker disclosed two setbacks tied to its experimental multiple sclerosis (MS) medicine tolebrutinib—a regulatory delay in the U.S. for one progressive MS form and a failed Phase 3