The Federal Circuit’s recent decision in United Therapeutics Corp. v. Liquidia Techs., Inc., No. 2022-2217, 2023 WL 4695903 (Fed. Cir. July 24, 2023), provides an interesting discussion on the written description and enablement of method of treatment claims where treatment of a subset of patients may not be safe or efficacious. Claim 1 of U.S. Patent 10,716,793, for example, reads as follows:

1. 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.