Sanofi sues Eli Lilly over Lantus patent infringement

French drug major Sanofi (Euronext: SAN) says it has filed a patent infringement suit against USA pharma firm Eli Lilly (NYSE: LLY) in the US District Court for the District of Delaware, alleging infringement of four patents.

The suit was triggered by notifications received from Lilly beginning in mid-December, in which Lilly stated that it had filed a New Drug Application with the US Food and Drug Administration for an insulin glargine drug product. Lilly also stated that its NDA included a paragraph IV certification challenging six of the seven Sanofi patents listed in the FDA Orange Book for Sanofi's Lantus (insulin glargine) and Lantus SoloStar products.

Sanofi's law suit triggers an automatic 30-month stay of approval by the FDA, meaning that Lilly’s proposed biosimilar product would be kept off the market until mid-2016. Lantus is the world's most prescribed insulin product, with annual global revenues about $7 billion, but is due to lose patent protection in the all-important US market next year.