United Therapeutics Corp. v. Liquidia Techs., Inc. United States Court of Appeals of the Federal Circuit, 2023 74 F.4th 1360

One of the patents at issue in this Hatch-Waxman litigation (the '793 patent'') claims a method of ''treating pulmonary hypertension'' with treprostinil, a vascular dilator, under specified conditions. The patent challenger argued that a skilled artisan would understand the plain and ordinary meaning of ''treating pulmonary hypertension'' to encompass a method that accomplishes that goal safely and effectively, and that the claims were invalid for failure to comply with the enablement and written description requirements because one of skill in the art would not believe that the recited use of treprostinil would be safe with respect to one category of patients experiencing pulmonary hypertension, i.e., Group 2 PH patients. The Federal Circuit agreed with the district court that, when read in context, the claim language ''treating pulmonary hypertension'' does not import any additional efficacy limitations or any safety limitations. The court pointed out that questions of safety and efficacy in patent law have long fallen under the purview of the FDA, and found that it would be improper to insert the FDA's responsibilities into claims by importing requirements where they do not recite such limitations. The court also noted that 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 requirements, unless these variants are specified in the claims.