Sanofi has announced that its oral, brain-penetrant BTK inhibitor, tolebrutinib, failed to meet the primary endpoint in the Phase III PERSEUS trial for primary progressive multiple sclerosis (PPMS). The global, double-blind, randomised study evaluated the drug's efficacy in slowing six-month composite confirmed disability progression compared to a placebo. Based on the outcome, Sanofi does not intend to submit a new drug application (NDA) for tolebrutinib in this indication. The drug is designed to cross the blood-brain barrier (BBB) and target immune cells within the central nervous system (CNS) to inhibit neuroinflammation.

In a separate regulatory update, US regulator the Food and Drug Administration (FDA) has extended the review period for tolebrutinib's NDA for non-relapsing secondary progressive MS (nrSPMS) by a further three months. The decision date had previously been delayed from September 2025 due to a major amendment submitted by Sanofi. The company has now provided additional information as requested by the agency, pushing the new decision deadline into 2026.

According to PharmCube's NextBiopharm® database, tolebrutinib's sales prospects rely solely in multiple sclerosis (MS) as development in non-MS indications has not been active in recent years. Click here to request a free trial for NextBiopharm®.