Tyvaso® (treprostinil)
Case Name: United Therapeutics Corp. v. Liquidia Technologies, Inc., Civ. No. 25-0368, 2025 WL 3719596 (M.D.N.C. Dec. 23, 2025) (Schroeder, J.)
Drug Product and Patent(s)-in-Suit: Tyvaso® (treprostinil); U.S. Patent Nos. 11,357,782 (“the ’782 patent”)
Nature of the Case and Issue(s) Presented: In January 2020, Liquidia filed its an NDA seeking approval to make and sell Yutrepia, a dry powder formulation of treprostinil used to treat certain pulmonary diseases. It referenced UTC’s Tyvaso product and filed Paragraph IV Certifications as to the patents that UTC listed in the Orange Book as covering Tyvaso. In June 2020, UTC sued Liquidia alleging infringement of U.S. Patent No. 10,716,793 (“the ’793 patent”). The court initially found that Yutrepia infringed the ‘793 patent, but that portion of the decision was later vacated after the PTAB ruled that the claims of the ’793 patent were unpatentable. In July 2023, Liquidia amended its NDA for Yutrepia to add pulmonary hypertension associated with interstitial lung disease as an indication for Yutrepia. UTC sued again alleging infringement of the ‘793 patent and the parties stipulated to the dismissal without prejudice of UTC’s claim in light of the Federal Circuit affirming the PTAB’s decision of unpatentability.
In May 2025, UTC filed this lawsuit alleging infringement of its ’782 patent, which it did not previously assert. The ’782 patent was not an Orange Book-listed patent because it claims a dry powder inhaler while Tyvaso is a nebulized mist inhalation device. UTC does not allege a cause of action pursuant to § 271(e)(2); rather, it sues pursuant to 35 U.S.C. § 271(b)-(c) and the Declaratory Judgment Act. Liquidia moved to dismiss under Rule 12(b)(6) or, in the alternative, to stay or transfer the action to the District of Delaware, on the basis of the rule against claim-splitting, the first-filed rule, claim preclusion, issue preclusion, and the Kessler doctrine. The court denied Liquidia’s motion.
Why UTC Prevailed:
- Claim-Splitting and the First-Filed Rule. Liquidia argued that UTC could have sued based on the ‘782 patent in the still-pending, second Hatch-Waxman case in Delaware and that the first-filed rule barred this suit because of the similarities with the second Hatch-Waxman case. UTC countered that its claims of infringement based on the ‘782 patent involved a different patent and could not have been brought previously. While the same parties and products are at issue, the instant lawsuit did not arise out of the same transaction or series of transactions. This case arose in response to Liquidia’s public announcement of its plan to launch Yutrepia. On the other hand, the prior Hatch-Waxman suits arose out of Liquidia’s NDA and accompanying Paragraph IV certifications for its Yutrepia product. Liquidia further argued that UTC could have nonetheless brought its claims for infringement of the ‘782 patent in the second Hatch-Waxman suit pursuant to the Declaratory Judgment Act. But given the uncertainty about whether district courts may exercise jurisdiction over a claim asserting future infringement of a non-Orange Book patent under the Declaratory Judgment Act when such a claim is based solely on the filing of an ANDA by a manufacturer, the court declined to conclude at this stage that the same transaction requirement has been satisfied in this case, and the issues raised are not similar enough to implicate the first-filed rule.
- Claim Preclusion. Next, Liquidia argued that UTC sought to relitigate matters ended by final judgment in the first Hatch-Waxman suit and, further, because the parties stipulated to the dismissal of the claim of infringement of the ‘793 patent in the second Hatch-Waxman suit, UTC could not now bring an infringement claim for a “virtually identical” patent involving the same parties and accused product. UTC responded that the ‘782 and ‘793 patents are materially different and that it could not have asserted the ‘782 patent in the prior Hatch-Waxman suits, thereby foreclosing the application of claim preclusion. The court started out where it left off in the preceding section, reiterating its finding that the present suit did not arise out of the same transaction or series of transactions as either Hatch-Waxman suit. In addition, the court found that Liquidia had not demonstrated enough overlap between the ‘782 patent and the ‘793 patent for the court to conclude at the Rule 12 stage that the two patents are “essentially the same.” Therefore, claim preclusion did not support dismissal.
- Issue Preclusion. Liquidia argued that issue preclusion also barred this patent infringement action because the ‘793 patent and the ‘782 patent contain substantially similar claims that do not differ in patentably significant ways and that the alleged infringing activity here did not differ from the alleged infringing activity in the Hatch-Waxman suits. For reasons stated previously—the claims of the ‘782 patent differ materially from those of the invalidated ‘793 patent, issue preclusion was inapplicable. Specifically, the ‘782 patent contemplated an additional dose, administered at least three hours after the first dose. The ‘793 patent’s claims make no mention of an additional dose event.
- Kessler Doctrine. Finally, Liquidia argued that the Federal Circuit’s Kessler doctrine barred UTC’s claims of infringement of the ‘782 patent because UTC alleged that Yutrepia infringed the ‘782 patent in substantially the same manner as in the Hatch-Waxman suits. The Kessler doctrine precludes “assertions of a patent against even post-judgment activity if the earlier judgment held that ‘essentially the same’ accused activity did not infringe that patent.” Under Kessler, “a party who obtains a final adjudication in its favor obtains ‘the right to have that which it lawfully produces freely bought and sold without restraint or interference.’” But again, Liquidia had not demonstrated that the ‘793 patent and the ‘782 patent are so indistinguishable as to implicate the Kessler doctrine’s bar against serial litigation, even though the parties and accused product remain the same.
