In United Therapeutics Corporation v. Liquidia Technologies, Inc., the U.S. Court of Appeals for the Federal Circuit held that a claim to a method of treatment for pulmonary hypertension was not invalid for lack of enablement or written description. The claims, construed as encompassing a method of treatment for all five types or groups of pulmonary hypertension, did not require undue experimentation even though there were safety concerns in treating one of the five subgroups. The claims did not require that the treatment was safe or effective, only that the treatment result in a specific effect — an improvement in a patient’s hemodynamics. The Federal Circuit also held that, unless variants are specified in the claims, the specification need not separately disclose each variant of a medical condition to satisfy the written description and enablement requirements.
Take Away #1: Define the effects of the treatment method in the specification. In this case, based on statements in the specification, the Federal Circuit found that a “therapeutically effective” dose has specific effects, such as vasodilating the pulmonary vasculature, improving hemodynamics, and “in this way for a single dose, treat[ing] a patient’s elevated pulmonary blood pressure. . . .” Tying the “treatment” to specific physical effects, rather than general improvement, will help to prevent a court from construing the method of treatment claim as including a requirement that the treatment be safe or effective.
Take Away #2: Consider different patient subgroups in drafting claims. While the claims at issue here did not differentiate between patient groups who may respond to treatment differently, in drafting patent claims, you may want to consider differentiating between patient subgroups, particularly if the data shows the treatment does not have a beneficial effect, or to distinguish over the prior art.
Background on United Therapeutics Corporation v. Liquidia Technologies, Inc.
The patents-in-suit, owned by plaintiff United Therapeutics, are generally directed to methods of treating pulmonary hypertension and to pharmaceutical compositions comprising treprostinil. United Therapeutics markets Tyvaso®, an inhaled solution formulation of treprostinil approved for the treatment of pulmonary hypertension, a condition characterized by abnormally high blood pressure in the lungs. Defendant Liquidia filed a New Drug Application for Yutrepia™, a dry powder inhalation formulation of treprostinil.
Treprostinil is used in treating pulmonary hypertension because it is a vasodilator that reduces vasoconstriction in the pulmonary vasculature, thereby decreasing blood pressure. There are five different subgroups of pulmonary hypertension, including pulmonary hypertension related to left-heart disease (referred to in the decision as “Group 2 PH patients”). Each group may require group-specific treatment, and, in particular, the record demonstrated that a “skilled artisan would have concerns about administering inhaled treprostinil to Group 2 PH patients” because, in a prior study, those patients experienced increased mortality.
The Method of Treatment
The method of treatment claims generally provided a method of “treating pulmonary hypertension comprising administering by inhalation to a human suffering from pulmonary hypertension a therapeutically effective single event dose of a formulation comprising treprostinil or a pharmaceutically acceptable salt thereof with an inhalation device, wherein the therapeutically effective single event dose comprises from 15 micrograms to 90 micrograms of treprostinil or a pharmaceutically acceptable salt thereof delivered in 1 to 3 breaths.”
The district court found that Liquidia infringed the method of treatment claims, and that the claims were not invalid for lack of written description or enablement. The district court, construing the claim limitation of “treating pulmonary hypertension” as including all five patient subgroups, found that a “skilled artisan would not need to engage in undue experimentation to practice the full scope of the claimed treatment of pulmonary hypertension, despite potential safety concerns in treating Group 2 PH patients, and that the claims did not require safety and efficacy.” The district court also found that the claims were not invalid for lack of written description, finding that “a skilled artisan would, based on the specification, understand that treprostinil would effectively vasodilate the pulmonary vasculature, improve hemodynamics, and treat a patient’s elevated pulmonary blood pressure.”
The Federal Circuit’s Decision
The Federal Circuit affirmed. The plain and ordinary meaning of “treating pulmonary hypertension” includes treating all five groups of pulmonary hypertension patients. Neither the claims nor the specification limited the scope of “pulmonary hypertension” to a particular subgroup of patients. Further, the term “therapeutically effective,” which was construed as “a dose given in a single treatment session that causes an improvement in a patient’s hemodynamics (reduced PAP or PVR),” did not import any safety or efficacy requirements. Such requirements are the purview of the U.S. Food and Drug Administration.
The Federal Circuit rejected Liquidia’s argument that the claims lacked written description and enablement because the specification lacked guidance or examples of treating Group 2 PH patients. While treating such patients may generate safety concerns, the 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.” A study showed that even though administration of treprostinil increased mortality in Group 2 PH patients, it nonetheless improved those patients’ hemodynamics.
Likewise, the specification satisfied the written description requirement, because a separate disclosure is not required for each individual variant of a condition to satisfy enablement and written description requirements “unless these variants are specified in the claims. 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.”
The Federal Circuit upheld the District of Delaware’s decision that (1) the method of treatment claims were not invalid and were infringed by Liquidia and (2) the composition claims were invalid as anticipated, but were otherwise infringed by Liquidia.
