United States: Takeaways From United Therapeutics Corporation v. Liquidia Technologies Incorporated

On July 24, 2023, the United States Court of Appeals for the Federal Circuit issued a precedential opinion in United Therapeutics Corp. v. Liquidia Technologies, Inc. that affirmed the United States District Court for the District of Delaware's decision that (1) claims 1, 4, and 6-8 of U.S. Patent 10,716,793 ('793 patent) are not invalid and are infringed by Liquidia Technologies and (2) claims 1-3 of U.S. Patent 9,593,066 ('066 patent) are invalid as anticipated, but are otherwise infringed by Liquidia Technologies.¹ The decision, written by Judge Lourie and joined by Judge Dyk and Judge Stoll, focuses on the claim language and offers important guidance concerning the application of the enablement and written description provisions of 35 U.S.C. § 112 to method-of-treatment claims. The decision also reiterates that the anticipation analysis for product-by-process claims do not require an anticipatory product to have been made by the claimed process.

United Therapeutics holds a New Drug Application (NDA) for TYVASO^®, a treprostinil solution used for the treatment of pulmonary hypertension. Liquidia Technologies filed a NDA under § 505(b)(2) for its drug Yutrepia", an inhalation formulation of treprostinil that is not a generic version of any currently marketed drug. Yutrepia^TM is also indicated for the treatment of pulmonary hypertension. There are five subgroups of pulmonary hypertension, each of which may require group-specific treatment.² However, the specifications of the asserted patents provide guidance on treating only certain types of pulmonary hypertension.

United Therapeutics sued Liquidia Technologies pursuant to § 505(c)(3)(C) alleging infringement of the '066 and '793 patents. A trial was held and the district court concluded that (1) claims 1, 4, and 6-8 of '793 patent are not invalid and are infringed, and (2) claims 1-3 of '066 patent are invalid as anticipated, but are otherwise infringed.³

Liquidia Technologies appealed the decision and raised five issues before the Federal Circuit:

(1) The district court erred in construing the claim limitation "treating pulmonary hypertension" in claim 1 of the '793 patent not to include safety and efficacy;

(2) The district court erred in finding the asserted claims of the '793 patent enabled;

(3) The district court erred in finding the asserted claims of the '793 patent supported by written description

(4) The district court erred in finding Liquidia Technologies liable for induced infringement of claims 1, 4, and 6-8 of the '793 patent; and

(5) The district court erred in finding claims 1-3 of the '066 patent to be infringed.

United Therapeutics raised two issues on cross-appeal:

(1) The district court erred in finding that Liquidia Technologies does not infringe claims 6 and 8 of the '066 patent; and

(2) The district court erred in finding that claims 1-3, 6, and 9 of the '066 patent are invalid as anticipated by Moriarty.

Application of Section 112 for Method-of-Treatment Claims

The Federal Circuit rejected Liquidia Technologies's argument that the district court clearly erred in finding the asserted claims of the '793 patent are adequately enabled, finding instead that "[t]he specification of the '793 patent sufficiently enables the scope of the claims."⁴ The Court also found that the claims are supported by adequate written description.

At issue before the panel was whether claims directed to "treating pulmonary hypertension" are unduly broad where the specification provides guidance on treating some—but not all—types of pulmonary hypertension. In affirming the decision of the district court, the Federal Circuit agreed that they are not. The Court explained that a "traditional genus and species" analysis is "inapt" when the claims recite a genus comprised of variants of a particular disease. The Court reasoned that it would be "incorrect" to "require a separate disclosure in the specification for each individual variant of the condition ... in order to satisfy the enablement and written description provisions of 35 U.S.C. § 112, unless these variants are specified in the claims."

Thus, the Federal Circuit clarified that a claim does not lack § 112 support simply because there are a "subset of patients who would not benefit from or should not take the claimed treatment."⁵ The decision stands in contrast to recent § 112 jurisprudence enforcing a more rigid disclosure requirement for genus/species claiming. See, e.g., Amgen Inc. v. Sanofi, 598 U.S. 594 (2023).

Safety and Efficacy Limitations in Claim Construction

Additionally, the Federal Circuit affirmed the district court's refusal to read safety and efficacy limitations into the asserted claims of the '793 patent. Although the claims recited "treating pulmonary hypertension" with a "therapeutically effective dose," the Court rejected Liquidia Technologies's argument that a skilled artisan would understand the claims to encompass "a method that accomplishes that goal safely and effectively" and therefore would exclude treatment of certain variants of pulmonary hypertension from the claim scope. The Court reiterated that absent specific limitations related to safety and efficacy, any such concerns do not fall under the purview of the Court. "We decline to insert the FDA's responsibilities into claims by importing requirements [of safety and efficacy] where they do not recite such limitations."⁶

Anticipation of Product-by-Process Claims

Finally, the Federal Circuit reiterated that product-by-process claims may be anticipated by a prior art disclosure of the claimed product, regardless of the process by which the product is made. In affirming the district court's invalidity finding with respect to claims 1-3, 6, and 9 of the '066 patent, the Court explained that because "these claims are product claims, they are anticipated by a disclosure of the same product irrespective of the processes by which they are made."⁷ Put simply, "a product-by-process claim is a product claim, even if claimed by a process by which it can be made."⁸

The decision provides useful guidance regarding limitations of certain § 112 invalidity arguments and claim construction arguments as applied to method-of-treatment claims. Additionally, the decision reiterates that product-by-process claims may be anticipated irrespective of the process by which they are made.