Core Insights - Sanofi's new drug application (NDA) for tolebrutinib has had its target action date extended by three months to December 28, 2025, due to the submission of additional analyses deemed a major amendment by the FDA [1][5] - Tolebrutinib is an investigational oral Bruton's tyrosine kinase (BTK) inhibitor aimed at treating non-relapsing, secondary progressive multiple sclerosis (nrSPMS) [1][6] - The NDA is supported by data from three late-stage studies, showing that tolebrutinib delayed disability progression compared to placebo and Aubagio [2][5] Company Overview - Tolebrutinib is the first and only brain-penetrant BTK inhibitor targeting both nrSPMS and relapsing MS (RMS) [6][8] - Currently, there are no approved therapies for nrSPMS, highlighting a significant unmet medical need [6][7] - Sanofi acquired tolebrutinib through its purchase of Principia in 2020, and it holds Breakthrough Therapy designation from the FDA for the nrSPMS indication [8] Clinical Development - The FDA accepted the NDA for tolebrutinib under its priority review pathway in March 2025 [2][5] - A phase III study (PERSEUS) is ongoing to evaluate tolebrutinib in primary progressive MS, with data expected by the end of 2025 [8] - In 2022, the FDA placed a partial clinical hold on phase III studies due to drug-induced liver injury cases, leading to the discontinuation of studies in myasthenia gravis [9] Market Performance - Year-to-date, Sanofi's shares have decreased by 2.5%, while the industry has seen a growth of 0.9% [3]