Sanofi, Eisai join Lilly's SCOTUS bid to save Cialis from 'overly broad' patent claims

Eli Lilly has a message for the U.S. Supreme Court: We aren’t going to take a $20 million patent loss for Cialis sitting down. Now, Lilly can count on a couple of friends ready to join the fight—and it's a fight that the rest of pharma might want to watch.

On Monday, Sanofi and Eisai Pharma threw their weight behind a lawsuit seeking to overturn a claim by Erfindergemeinschaft Uropep GBR (EUG) that ended Cialis’ patent protection in benign prostatic hyperplasia (BPH), a $20 million indication. Lilly called EUG’s original claim a “particularly egregious example of functional claiming,” in the suit (PDF).

Both Sanofi and Eisai doubled down on Lilly’s “functional claim” argument, saying EUG’s claim effectively roped off any drug formulations used to treat BPH through an enzyme inhibitor, a category Cialis falls under.

It's the sort of broad patent claim at issue in a variety of outstanding court cases, so it's no surprise other drugmakers want in. Lilly's lawsuit could have big implications for companies who've fallen prey to claims that rely on results rather than precise formulations. In fact, fighting "overly broad" patent claims is at the heart of Sanofi and Regeneron's fight to market PCSK9 inhibitor Praluent, which a Delaware jury said in February infringed on Amgen's older patent for Repatha.

RELATED: Eli Lilly throws SCOTUS hail mary in Cialis patent infringement fight

In this case, Sanofi and Eisai argued that the federal appeals court’s argument upholding EUG’s claim was at odds with decades of SCOTUS precedent.

“This will continue to occur indefinitely unless addressed … providing patent protection beyond what the inventor conceived of or disclosed to the public, breaking the essential bargain with the public that underlies our patent system,” Sanofi said in a legal brief Monday.

The French drugmaker also has a vested interest in Cialis patent rights. The company owns the rights to market over-the-counter Cialis in the U.S., U.K., Canada and Australia. Sanofi could also see shades of its own past in the Cialis fight after generic challengers to its Uroxatral gutted the drug’s chances in BPH back in 2012, an $81 million market at the time.

Kissei and Allergan’s own BPH alpha-blocker, marketed as Urief and Rapaflo in Japan and the U.S., respectively, also lost its battle with generic challengers in late 2018.

RELATED: Top 10 U.S. patent losses of 2017 -  Cialis

Lilly’s SCOTUS bid is the last line of defense for the drug after the arrival of generic challengers stateside and abroad has largely ended the drug’s blockbuster sales hopes. In 2018, Cialis saw a 20% drop in worldwide sales to $1.85 billion, driven by the drug’s loss of U.S. and European patent protection in late 2018 and 2017, respectively. In 2016, Cialis cleared $2.47 billion worldwide.

For the first quarter, Cialis raked in a little more than $308 million worldwide—a 38% drop from the previous year. U.S. sales took the worst of that decrease with sales plummeting to $143 million—a 54% drop from the year before.

Editor's Note: This story has been updated to correct a mistake.