The company scrapped development of another possible blockbuster cholesterol drug in December.

It is seen as a possible blockbuster that could help Sanofi's ambitions to expand in the treatment of diabetes.

U.S. regulators have asked for more data on Galvus, potentially delaying any approval of the possible blockbuster by a year and sending Novartis shares tumbling.

If successful in those studies, the drug is considered a possible blockbuster replacement for Bristol's poorly tolerated but widely used medicine Coumadin (warfarin).