TETON-2 results posted: inhaled treprostinil and lung function in idiopathic pulmonary fibrosis
On October 15, 2026, United Therapeutics' registry entry for the Phase 3 TETON-2 trial posted results. It reports a 95.6 mL difference in FVC change at Week 52 against placebo.
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On October 15, 2026, ClinicalTrials.gov first posted results for TETON-2 (NCT05255991), a Phase 3 study sponsored by United Therapeutics of inhaled treprostinil in idiopathic pulmonary fibrosis (IPF). The record describes a randomized, double-blind, placebo-controlled, multinational trial. The registry reports the numbers below; this story covers the posted record only, not any company statement or regulatory filing.
How the trial ran
Participants were randomly allocated 1:1 to inhaled treprostinil or placebo. Treprostinil was delivered by an ultrasonic nebulizer that emits a dose of approximately 6 mcg per breath, four times daily, titrated up to a target of 12 breaths or the participant's maximum clinically tolerated dose. The registry lists 593 participants in the baseline table, 298 on treprostinil and 295 on placebo. Participants could be on pirfenidone or nintedanib at a stable dose, and 146 of the 593 were on neither.
The study began on 2022-09-12, and primary completion was on June 30, 2025. The registry's outcome measures run from baseline to Week 52.
The primary result
The primary outcome was the change in absolute forced vital capacity (FVC) from baseline to Week 52, in mL. FVC is the amount of air a person can forcefully and quickly exhale after taking a deep breath. The registry reports a median change of -49.9 mL in the treprostinil group and -136.4 mL in the placebo group. The Hodges-Lehmann estimate of the treatment difference was 95.6 mL (95% confidence interval: 52.2 to 139.0), with a p-value below 0.0001 on a superiority test.
Secondary measures
For time to clinical worsening, defined in the record as death from any cause, hospitalization for a respiratory indication, or a 10% relative decline in % predicted FVC, 81 participants on treprostinil and 115 on placebo had an event. The hazard ratio was 0.71 (95% confidence interval: 0.53 to 0.95; p = 0.0191).
For time to first acute exacerbation of IPF, 9 participants on treprostinil and 17 on placebo had an event. The hazard ratio was 0.54 (95% confidence interval: 0.24 to 1.22; p = 0.1298). That interval includes 1, so the record does not show a difference on this measure.
Safety entries in the record
The adverse events section lists 21 deaths among 298 participants in the treprostinil group and 25 among 295 on placebo. Serious adverse events affected 75 participants on treprostinil and 68 on placebo.
What the record does not say
The posted record is a registry entry. It is not a peer-reviewed paper, and it is not a regulatory decision. The story relies only on the numbers the sponsor posted there.