Sanofi stock slumps after two setbacks on multiple-sclerosis drug
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Sanofi stock slumps after two setbacks on multiple-sclerosis drugListen(1 min)Listen(1 min)Shares of Sanofi slumped on Monday as the French drugmaker said a U.S. regulatory review of its multiple-sclerosis drug won’t be completed by the end of the year and that a trial for a different form of MS didn’t succeed.Sanofi said the review of what’s called tolebrutinib, to treat non-relapsing secondary progressive multiple sclerosis, will extend beyond Dec. 28, and that it expects further guidance by the U.S. Food and Drug Administration by the end of the first quarter.About the AuthorSteven Goldstein is based in London and responsible for MarketWatch's coverage of financial markets in Europe, with a particular focus on global macro and commodities. Previously, he was Washington bureau chief, directing MarketWatch's economic, political and regulatory coverage. Follow Steve on Twitter: @MKTWgoldstein.Copyright © 2025 MarketWatch, Inc. All rights reserved.