United Therapeutics Files Lawsuit Against FDA to Keep Exclusivity in PH-ILD Market

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Pictured: FDA Headquarters/iStock, hapabapa

United Therapeutics is calling out the FDA to maintain exclusivity in the pulmonary hypertension associated with interstitial lung disease market. Litigation announced Wednesday alleges the regulator allowed Liquidia to “skirt longstanding FDA rules, precedents and procedures” in its pending approval for its inhaled blood pressure drug. 

Liquidia’s Yutrepia (treprostinil) was granted tentative FDA approval in November 2021 for pulmonary arterial hypertension. In September 2023, the FDA accepted an amendment to the NDA to add pulmonary hypertension associated with interstitial lung disease (PH-ILD) to the label. The group of disorders causes scarring to the lungs. The agency missed its PDUFA goal date in January 2024.  

United has a similar product on the market—Tyvaso—which was approved in March 2021 as the first ever treatment for PH-ILD. The company alleges that FDA procedures should’ve required Liquidia to file a new NDA, rather than an amendment to one that was already pending.  

According to United, by filing an amendment instead of a new NDA, its competitor avoided a 30-month stay of approval that should have been required based on Liquidia relying on Tyvaso’s prior approval for their own.  

United previously sued Liquidia for patent infringement. The case is currently pending in court. 

The company believes the FDA “missed” its own legal and regulatory precedents in this case, denying United its right to delay Liquidia’s approval until the pending patent infringement case can be resolved. 

“We are simply asking that the FDA apply its own rules and precedents consistently to honor the Hatch-Waxman balance struck by Congress between innovators and imitators,” Dean Bunce, executive vice president at United, said in a statement. 

“Liquidia can rely on United Therapeutics’ innovation to speed its path to market, but the cost of that shortcut is that Liquidia must address the infringement claim against it before rushing to market.” 

Tyvaso broke into blockbuster status last year when its revenues increased 41% over 2022, bringing sales to $1.2 billion. The company credited much of its growth to a dry powder inhaler formulation, in addition to the original nebulizer solution. It’s currently the only FDA approved medication for PH-ILD and by far United’s best-selling product. 

Kate Goodwin is a freelance life science writer based in Des Moines, Iowa. She can be reached at kate.goodwin@biospace.com and on LinkedIn  

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