Sanofi reported that the Phase III Perseus study of BTK inhibitor tolebrutinib failed to meet its primary endpoint in primary progressive multiple sclerosis (PPMS), and the company warned that the FDA review for the non‑relapsing secondary progressive MS (nrSPMS) filing will likely extend beyond the Dec. 28 PDUFA date. Sanofi has submitted an expanded‑access protocol and reiterated belief in the drug’s risk‑benefit profile as it recalibrates development plans.