LIQ861 Inhalation Therapy for PAH Again Under FDA Review

The U.S. Food and Drug Administration (FDA) has accepted an updated application asking that the dry-powder inhalation therapy LIQ861 (treprostinil) be approved to treat pulmonary arterial hypertension (PAH).

Liquidia Corporation, the therapy’s developer, first requested approval in April 2020, but the FDA asked for more data on LIQ861 in a complete response letter issued in November.

Specifically, the regulatory agency requested more information and clarification of the medicine’s chemistry, manufacturing, and controls. Additional data also had to include further evidence of the safety of the portable device used to deliver LIQ861. No further clinical trial data or information regarding the therapy’s pharmacology or toxicology were required.

In confirming its acceptance of the resubmitted application, the FDA set Nov. 7 as the intended date for a decision on possible approval, according to a press release.

If given, however, this approval would be tentative. Final approval would be subject to the resolution of the pending patent infringement lawsuit initiated by United Therapeutics. Earlier this year, the United States Patent and Trademark Office issued a patent to Liquidia relating to LIQ861, which included claims covering methods of treating patients with any form of pulmonary hypertension. United Therapeutics has filed claims alleging infringement of similar patents it holds.

United Therapeutics also submitted an application to the FDA in April seeking approval of Tyvaso DPI, a dry-powder inhalation therapy similar to LIQ861, and a reformulation of its approved treatment Tyvaso, a nebulized treprostinil solution.

The FDA may not fully approve LIQ861 until a 30-month regulatory stay expires in October 2022 or an earlier court judgment arrives that is unfavorable to United Therapeutics, Liquidia stated in its release. 

Using a palm-sized portable inhaler, LIQ861 is a dry-powder formulation of treprostinil — a vasodilator that relaxes and widens blood vessels, lowering blood pressure, which is elevated in the pulmonary arteries of people with PAH. 

The therapy uses Liquidia’s PRINT technology, which aims to safely enhance the deep-lung delivery of treprostinil using particles that are uniform in size, shape, and composition, the company reports. 

Liquidia’s original FDA application was based on the results of the INSPIRE Phase 3 clinical trial (NCT03399604), which demonstrated that LIQ861 improved exercise capacity and quality of life in adults with PAH, and was safe and well-tolerated.