Sanofi SA, whose top-selling Lantus helps diabetics control blood sugar levels, has filed a lawsuit accusing Eli Lilly and Co of infringing seven patents related to insulin and devices used to deliver it.
Through its complaint made public on Tuesday in the U.S. District Court in Wilmington, Delaware, Sanofi is seeking to halt Lilly's proposed commercial marketing in the United States of a rival treatment, known as Abasria, saying the sale would violate its rights.
Sanofi's lawsuit, and a narrower lawsuit filed in January, came after Lilly and German partner Boehringer Ingelheim Corp last December said they had applied with the U.S. Food and Drug Administration to sell a generic version of Lantus, whose active ingredient is insulin glargine.
A European regulator, the European Medicine Agency, recommended approval of Lilly's drug last month.
Lantus is the world's most widely prescribed insulin. Sales totaled 5.72 billion euros (US$7.78 billion) in 2013.
Lilly spokeswoman Tammy Hull said the Indianapolis-based company is reviewing Sanofi's latest lawsuit, and "does not believe the application infringes any of the asserted patents." Sanofi is based in Paris.
Lantus will lose U.S. patent protection in February 2015, and Sanofi and Lilly have been working on experimental insulin therapies to replace it.
Sanofi's product, Toujeo, has triple the concentration of insulin glargine as Lantus. Lilly's proposed product has the same molecular formula as Lantus.
The original lawsuit triggered an automatic 30-month stay of FDA approval of Lilly's drug, keeping it off the market until at least the middle of 2016.
Diabetes occurs when the body fails to properly produce or use the hormone insulin, and is linked to health problems including heart disease, kidney disease and blindness.
The disease afflicts about 382 million people worldwide and 29.1 million Americans, according to data from the International Diabetes Federation and the American Diabetes Association.
The case is Sanofi-Aventis US LLC et al v. Eli Lilly and Co, U.S. District Court, District of Delaware, No. 14-00884.
(1 euro = US$1.361)
(Reporting by Jonathan Stempel in New York; editing by Matthew Lewis)