FDA Accepts Sanofi's Filing for Multiple Sclerosis Drug Tolebrutinib

Core Viewpoint - Sanofi's investigational BTK inhibitor tolebrutinib has received priority review from the FDA for treating non-relapsing secondary progressive multiple sclerosis (nrSPMS), with a final decision expected by September 28, 2025 [1][2]. Group 1: Regulatory Filing and Studies - The FDA's acceptance of the filing is based on data from three late-stage studies, including one focused on nrSPMS and two on relapsing MS (RMS), demonstrating that tolebrutinib delayed disability progression compared to placebo [2]. - A similar regulatory filing is under review by the EMA, also supported by the same studies [2]. Group 2: Unique Treatment Potential - Tolebrutinib is positioned as the first and only brain-penetrant BTK inhibitor for both nrSPMS and RMS, targeting smoldering neuroinflammation, which is crucial for addressing disability accumulation in MS [3]. - Currently, there are no approved therapies for nrSPMS, highlighting a significant unmet need that tolebrutinib could potentially fulfill [4]. Group 3: Stock Performance and Future Studies - Year-to-date, Sanofi's shares have increased by 16%, outperforming the industry average growth of 6% [7]. - Sanofi is also evaluating tolebrutinib in a phase III study for primary progressive MS, with data expected in the second half of 2025 [8]. Group 4: Previous Clinical Holds - In 2022, the FDA placed a partial clinical hold on Sanofi's phase III studies for tolebrutinib due to cases of drug-induced liver injury observed in participants [9]. - The studies for myasthenia gravis (MG) indications were eventually discontinued after evaluating the competitive treatment landscape [10].