Sanofi lawsuit tries to hold Merck Lantus biosimilar at bay

Just because Sanofi negotiated a settlement that allows Eli Lilly to launch its Lantus biosimilar injector in mid-December does not mean the French drugmaker is prepared to cede U.S. market share to any comer. So Sanofi has filed a patent lawsuit against Merck & Co., which has its own knockoff targeted at the $4.5 billion in U.S. Lantus sales.

Sanofi ($SNY) today said that its suit, filed Friday, was triggered by a notification from Merck ($MRK) in early August that the Kenilworth, NJ, drugmaker had filed its application for approval with the FDA and is challenging all 10 Sanofi patents holds in the U.S. on Lantus and its SoloStar products.

Merck, in an emailed comment, said today it is confident that its application “does not infringe any valid claim of the asserted patents for the originator insulin glargine, Lantus.”

Lantus is Sanofi’ cornerstone product, last year accounting for more than 17% of its total revenues. But it is already is under siege in the Europe from the biosimilar that Lilly ($LLY) and Boehringer biosimilar developed and in the U.S. from other diabetes drugs. That has forced Sanofi to offer deeper discounts to payers to stem the erosion of Lantus market share.  Lantus sales in the U.S. last year were down 20.5% to €4.023 billion ($4.491 billion) and in H1 of this year fell another 15% to €2.38 billion ($2.7 billion).

Sanofi last year launched Toujeo, its long-acting follow-up to Lantus, with hopes of getting patients moved to it before competition materialized. It has insisted that it will not offer discounts on the drug, that its data of performing even better than Lantus as preventing low blood sugar episodes at night, would convince doctors to prescribe it. That decision has been criticized by some analysts who think Sanofi needs to do whatever it can to build up Toujeo’s market share before the biosimilars hit.

So far, Toujeo has generated only a fraction of what Lantus does, $157.5 million worldwide in Q2, with $124 million of that in the U.S. Analysts have projected that it might reach about $1.7 billion in sales by 2020, still way short of what Lantus pumps into Sanofi's coffers.

Sanofi CEO Olivier Brandicourt had hoped to offset the huge loss of Lantus sales with a deal to buy Medivation ($MDVN) and get its hot-selling cancer drug Xtandi, but that hope was snatched away last month when Pfizer ($PFE) offered almost $30 a share more than Sanofi, agreeing to buy Medivation for about $14 billion, an offer so rich that it left many analysts shaking their heads.

- here’s the Sanofi release

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