Published by Global Banking and Finance Review
Posted on December 15, 2025
2 min readLast updated: January 20, 2026
Sanofi faces another FDA delay for its MS drug, impacting shares and raising concerns over its drug pipeline. The decision is now expected by Q1 2026.
By Bhanvi Satija
Dec 15 (Reuters) - French drugmaker Sanofi on Monday flagged another delay to a U.S. regulatory decision for its experimental multiple sclerosis drug and reported disappointing results from a late-stage study, sending shares of the company down 2%.
Shares initially fell over 5% to the bottom of the SBF 120 index of Paris' most traded stocks before paring losses. The stock has declined over 13% this year.
Analysts said the setbacks could undermine confidence in Sanofi's pipeline of new drugs after weak results of its experimental drugs for eczema and smoker's lung reported earlier in the year. The drugmaker is under pressure to diversify its growth beyond blockbuster asthma drug Dupixent.
Sanofi said that the U.S. Food and Drug Administration's decision on its tolebrutinib drug to treat non-relapsing secondary progressive multiple sclerosis will push beyond the action date of December 28, a second delay to a decision that was initially expected in September. It expects further guidance from the FDA by the end of the first quarter of 2026.
The delay could lower chances of approval for the drug, BofA analysts said, and cast doubt over 1.4 billion euros in sales that the drug was expected to bring in at peak.
The company also reported that tolebrutinib failed to slow disability progression in a late-stage trial in patients with primary progressive multiple sclerosis, a form of the autoimmune disease that it estimates accounts for about 10% of cases.
Analysts said the results were a negative surprise, especially in light of recent data from a rival drug from Roche that was shown to significantly reduce the annualised relapse rate when compared with another drug.
The Sanofi drug was granted breakthrough therapy designation by the FDA in December 2024 and is also under regulatory review in the European Union.
It was provisionally approved in the United Arab Emirates in July to treat non-relapsing secondary progressive multiple sclerosis and to slow disability accumulation independent of relapse activity in adults.
(Reporting by Mathias de Rozario in Gdansk and Bhanvi Satija in London, editing by Milla Nissi-Prussak, Bernadette Baum and Tomasz Janowski)
A late-stage trial, often referred to as Phase III, is a critical phase in drug development where the drug is tested on a larger group of patients to confirm its effectiveness and monitor side effects.
Breakthrough therapy designation is a special status granted by the FDA to expedite the development and review of drugs that show promise in treating serious conditions.
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