The pivotal TETON-1 phase 3 study of nebulized Tyvaso® (treprostinil) Inhalation Solution in idiopathic pulmonary fibrosis (IPF) preserved lung function as measured by absolute forced vital capacity (FVC) and demonstrated reduced risk of a clinical worsening event, meeting both its primary endpoint and a key secondary endpoint with statistical significance, respectively

In combined analyses of TETON-1 and TETON-2 — also included in the NEJM publication and presented at ATS — nebulized Tyvaso achieved statistically significant treatment effects across the primary and most secondary efficacy endpoints

Nebulized Tyvaso combines direct lung delivery with multi-modal activity across fibrotic, vascular, and inflammatory pathways that are not currently addressed by existing IPF therapies

United Therapeutics Corporation (Nasdaq: UTHR), a public benefit corporation, today announced that the New England Journal of Medicine has published the full results of its TETON-1 study, as well as combined analyses of its TETON-1 and TETON-2 studies, evaluating the use of nebulized Tyvaso for the treatment of IPF. The publication is available here. A summary of the publication was also presented today during a symposium at the annual meeting of the American Thoracic Society (ATS) International Conference in Orlando. The use of nebulized Tyvaso for IPF has not been approved by the U.S. Food and Drug Administration (FDA)and remains investigational for IPF.

The results of TETON-1 were also presented at ATS during the Breaking News: 2026 Clinical Trial Results in Pulmonary Medicine session on Sunday, May 17. Combined results from TETON-1 and TETON-2 were presented today during an oral session at ATS.

TETON-1 met its primary efficacy endpoint, with nebulized Tyvaso demonstrating statistically significant improvement in absolute FVC relative to placebo from baseline to week 52 in an IPF population broadly treated with background therapy. The median change in FVC at week 52 was −43.3 mL (95% confidence interval [CI], −92.1 to −9.1) in the nebulized Tyvaso group and −196.2 mL (95% CI, −227.1 to −155.6) in the placebo group; between-group difference was 130.1 mL (95% CI, 82.2 to 178.1; P<0.001).

Nebulized Tyvaso reduced the risk of a clinical worsening event by 33% (hazard ratio [HR], 0.67; 95% CI, 0.52 to 0.88; P=0.0034) relative to placebo, a statistically significant improvement in this key secondary endpoint. Nebulized Tyvaso showed numerical improvement in other important secondary endpoints, including improved change in percent of predicted FVC, King's Brief Interstitial Lung Disease quality of life questionnaire (K-BILD), and change in percent of predicted diffusion capacity of lungs for carbon monoxide (DLCO).

Benefits of nebulized Tyvaso in TETON-1 were observed across all subgroups, including use of background therapy (nintedanib, pirfenidone, or no background therapy), smoking status, and supplemental oxygen use.

Combined analyses of TETON-1 and TETON-2 showed that nebulized Tyvaso achieved statistically significant treatment effects compared to placebo from baseline to week 52 for the primary endpoint and for most key secondary endpoints.

The median change in FVC at 52 weeks in the combined data set was −45.4 mL (95% CI, −73.8 to −23.1) in the nebulized Tyvaso group and −161.7 mL (95% CI, −194.5 to −134.1) in the placebo arm; between-group difference was 111.8 mL (95% CI, 79.7 to 144; P<0.0001).

Nebulized Tyvaso reduced the risk of a clinical worsening event in the combined data set by 31% (HR: 0.69; 95% CI, 0.57 to 0.84; P=0.0002) and the risk of acute IPF exacerbation by 48% (HR: 0.52; 95% CI, 0.30 to 0.91; P=0.0223) relative to placebo. Nebulized Tyvaso also achieved statistically significant improvements in changes in percent predicted FVC, K-BILD score, and DLCO. Overall survival at week 52 trended in favor of Tyvaso but did not meet statistical significance.

United Therapeutics plans to seek priority review of a supplemental New Drug Application, to be submitted to the FDA by the end of this summer, to add IPF to the labeled indications for nebulized Tyvaso based on data from the TETON-1 and TETON-2 studies. Both the FDA and the European Medicines Agency have granted orphan designation for treprostinil to treat IPF.