United Therapeutics Corporation v. Liquidia Technologies, Inc., Appeal Nos. 2022-2217, 2023-1021 (Fed. Cir. July 24, 2023)

In the Federal Circuit’s only precedential patent case this week, the Court considered questions that are tangentially related to the convergence of genus/species patent claim issues with the written description and enablement requirements in Section 112.  This has been an emergent issue that was recently considered by the Supreme Court in Amgen v. Sanofi, which we wrote about here. In this week’s Case of the Week, the Court found that it was inappropriate to consider the genus/species argument, where the claims covered the treatment of five patient groups.  Read on to understand why.

This case is an appeal from a district court Hatch-Waxman case involving Tyvaso, an inhaled solution approved for the treatment of pulmonary hypertension that uses treprostinil.  Experts consider there to be five subgroups of pulmonary hypertensions.  Groups 1, 3, 4, and 5 are caused by conditions affecting the pulmonary arteries or precapillary vessels of the lungs; Group 2, on the other hand, is referred to as pulmonary venous hypertension and typically develops as a result of a cardiac-based etiology.  Due to differing etiologies, each group may require group-specific treatment.

At issue were two patents directed to methods of treating pulmonary hypertension and compositions comprising treprostinil.  Liquidia filed an NDA for its own inhalation formulation of treprostinil, which triggered a lawsuit concerning infringement and validity of the two patents.  One of the two patents, the ‘793 Patent, claimed “A method of treating pulmonary hypertension” using treprostinil.  The district court found that Liquidia would be liable for induced infringement and that the claims were not invalid, including under Section 112.

The nub had to do with the phrase “method for treating pulmonary hypertension.”  Liquidia argued that this would have required certain safety and efficacy, which is important because there were potential safety concerns with respect to the Group 2 patients.

The Federal Circuit declined to import a safety and efficacy requirement into the claims, noting that “[q]uestions of safety and efficacy in patent law have long fallen under the purview of the FDA. . . . We decline to insert the FDA’s responsibilities into claims by importing requirements where they do not recite such limitations.”

The Court then turned to the anticipation and enablement requirements raised by Liquidia, which had argued that the “patent provides no guidance or examples of treating Group 2 PH patients, and thus that a skilled artisan would have to engage in undue experimentation to practice the full scope of the claimed invention (i.e., treating Group 2 PH patients).”  The Court affirmed the district court’s finding that the patent complied with Section 112.  Specifically, the district court had “properly relied on expert testimony and record evidence to conclude that a skilled artisan would understand that the claimed administration of treprostinil would vasodilate the pulmonary vasculature, improve hemodynamics, and in this way for a single dose, treat a patient’s elevated pulmonary blood pressure independent of the type (i.e., group) of pulmonary hypertension patient.  That was all that the claims require.”  The fact that one study of Group 2 patients failed due to increased mortality did not detract from the fact that the claim “treated pulmonary hypertension” in a number of Group 2 patients.

The Court also agreed with respect to the written description requirement.  Liquidia had argued that the patent did not disclose the full breadth of what it claimed—i.e., how to treat pulmonary hypertension in all patients, including those in Group 2.  Liquidia had argued that Group 2 patients should have been seen as a species within the larger genus of pulmonary hypertension patients.  The Court disagreed:

But analogizing a subset of patients having a variant of a particular disease to traditional genus and species claims is inapt. It would be incorrect to fractionate a disease or condition that a method of treatment claim is directed to, and to require a separate disclosure in the specification for each individual variant of the condition (here, an individual group of pulmonary hypertension patients) in order to satisfy the enablement and written description provisions of 35 U.S.C. § 112, unless these variants are specified in the claims. . . . Every claim to a method of treatment of an ailment has refinements. That is, for any given method of treatment claim, there may be a subset of patients who would not benefit from or should not take the claimed treatment. . . . That does not mean that such claims are not sufficiently enabled or supported by written description. A subset of unresponsive patients is not analogous to unsupported species in a generic claim to chemical compounds.

Liquidia also argued that it could not be liable for induced infringement because the patent has been found invalid in an IPR proceeding.  The Federal Circuit disagreed because the IPR decision was pending on appeal, and “A pending, non-final litigation does not negate an intent to infringe.”  The claims are only canceled when the Director issues a certificate confirming unpatentability after all appeals are exhausted.

The Court also found claims from another patent invalid as anticipated, over United Therapeutics’ cross-appeal.  The specification required an impurity level of 99.7%-99.9%, and the prior art disclosed 99.7% purity.

The opinion can be found here.

By Nika Aldrich

This article summarizes aspects of the law and does not constitute legal advice. For legal advice for your situation, you should contact an attorney.

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