Sanofi ups the legal ante to block Lilly's Lantus biosimilar

Sanofi ($SNY) has filed another lawsuit against Eli Lilly ($LLY) in hopes of beating back a biosimilar challenge for its top-selling insulin product, claiming its rival's in-development knockoff infringes its intellectual property.

The latest suit casts a broader net than the one Sanofi filed in January, alleging that Lilly violated 7 of the drugmaker's patents in its work on LY2963016, to be marketed as Abasria. The biosimilar, developed alongside diabetes partner Boehringer Ingelheim, has the same active ingredient as Lantus, Sanofi's insulin analog that accounted for about $7.8 billion in sales last year.

But Lilly's reach for a share of that revenue will have to wait, at least in the U.S. Sanofi's first suit, which claimed four infringements, triggered a 30-month delay for Abasria's eventual FDA approval, stalling a stateside launch until mid-2016 unless the parties can come to a resolution. The initial plan was to hit the market as soon as Lantus loses patent protection in February 2015.

Lilly said in an email that the company is reviewing the latest lawsuit but maintains that its Abasria application doesn't step on any of the patents in question.

If the dispute stretches out to full term, Lilly may be looking at a different market for long-acting insulin by the time it gets its product on shelves. Merck ($MRK), with the help of a joint venture between Samsung and Biogen Idec ($BIIB), is working up a Lantus biosimilar of its own, and the FDA is already reviewing Toujeo, Sanofi's long-acting Lantus successor.

Meanwhile, in Europe, Lilly's outlook is much brighter. Last month, the European Medicines Agency's Committee for Medicinal Products for Human Use recommended Abasria for full approval, which is expected in the next month or so. An EU approval would give Lilly and Boehringer a shot at the roughly $1.1 billion in sales Lantus pulled in on the continent last year.

- here's the lawsuit