Sanofi may win U.S. approval of $3 billion eczema drug by March

French drugmaker Sanofi (SASY.PA) and its U.S. partner Regeneron Pharmaceuticals (REGN.O) could win U.S. approval for their keenly awaited new eczema drug dupilumab, seen by analysts as a potential $3 billion-a-year seller, by next March.