United Therapeutics Corporation Shares TETON-2 Phase 3 Trial Findings in The New England Journal of Medicine
United Therapeutics Corporation announced that the complete findings from its Phase 3 TETON-2 clinical trial evaluating nebulized Tyvaso® (treprostinil) inhalation solution for the treatment of Idiopathic Pulmonary Fibrosis (IPF) have been published in the prestigious The New England Journal of Medicine. The study represents an important milestone in pulmonary medicine, highlighting the potential of inhaled therapy to slow disease progression in patients suffering from this severe and progressive lung condition.
Breakthrough Findings in IPF Treatment
The TETON-2 trial demonstrated that treatment with Tyvaso inhalation solution resulted in statistically significant preservation of lung function in patients with idiopathic pulmonary fibrosis. The primary measurement used to evaluate lung function was absolute forced vital capacity (FVC), a widely recognized marker used to assess disease progression in fibrotic lung diseases. Over a 52-week treatment period, patients receiving nebulized Tyvaso experienced substantially less decline in FVC compared with those receiving placebo.
This achievement is particularly notable because the TETON-2 study is the first clinical trial to show that an inhaled therapy can slow the progression of fibrosis in IPF patients, as measured by changes in FVC. Researchers emphasized that demonstrating this benefit using a non-systemic, inhaled approach represents a meaningful advance in the management of this challenging disease.
Idiopathic pulmonary fibrosis is a chronic, progressive condition characterized by scarring of the lung tissue, which gradually impairs breathing and oxygen transfer. Treatment options remain limited, and many patients continue to experience progressive decline in lung function despite existing therapies. The results from the TETON-2 study suggest that Tyvaso may offer a new therapeutic option that directly targets the lungs through inhalation.
Significant Improvements in Lung Function
The study met its primary endpoint, showing a statistically significant improvement in the change in absolute FVC from baseline to week 52 in patients treated with nebulized Tyvaso compared with those receiving placebo. The median decline in FVC at week 52 was −49.9 mL in the Tyvaso treatment group, while patients in the placebo group experienced a larger decline of −136.4 mL. The between-group difference of 95.6 mL was statistically significant, demonstrating the treatment’s effectiveness in slowing the deterioration of lung function.
In addition to improving the primary endpoint, nebulized Tyvaso also demonstrated significant improvements across several secondary outcomes. One of the most important findings was a reduction in the risk of clinical worsening events. Patients receiving Tyvaso experienced a 29% lower risk of disease worsening compared with those in the placebo group. Clinical worsening events included disease progression, acute exacerbations, hospitalization, or death related to IPF.
Researchers also observed improvements in additional key clinical measurements, including the percentage of predicted FVC, changes in the King’s Brief Interstitial Lung Disease quality-of-life questionnaire (K-BILD), and diffusion capacity of the lungs for carbon monoxide (DLCO), which reflects the lungs’ ability to transfer oxygen into the bloodstream. These findings collectively indicate that Tyvaso may positively influence multiple aspects of disease progression and patient wellbeing.
Benefits Observed Across Patient Subgroups
Importantly, the benefits of Tyvaso treatment were observed across a wide range of patient subgroups. Patients receiving background antifibrotic therapies such as nintedanib or pirfenidone experienced similar benefits compared with those who were not receiving additional antifibrotic medications. Improvements were also seen regardless of smoking status or the use of supplemental oxygen.
This consistency across subgroups suggests that Tyvaso may be broadly applicable in the treatment of IPF and could potentially be used alongside existing therapies. Approximately 75% of patients enrolled in the trial were already receiving background antifibrotic treatment, highlighting that the observed benefits occurred in a real-world clinical context where combination therapy is common.
Expert Perspectives on the Trial Results
Clinical investigators involved in the study highlighted the significance of the results. Lead study author Dr. Steven D. Nathan emphasized that the TETON-2 trial not only met its primary endpoint but also achieved statistical significance in key secondary endpoints such as time to clinical worsening. He also noted improvements in diffusion capacity and patient-reported quality of life measures.
According to Dr. Nathan, the results demonstrate the potential advantages of delivering medication directly to the lungs through inhalation. This targeted approach may enhance treatment effectiveness while minimizing systemic exposure, offering a promising therapeutic strategy for patients with mild to moderate IPF.
Leadership at United Therapeutics also underscored the broader impact of the findings. Company executives described the publication of the study results in a leading medical journal as a pivotal moment for the IPF community. For many patients living with this disease, treatment options have remained limited, and the availability of a new inhaled antifibrotic therapy could represent a meaningful advance.
Potential First Inhaled Anti-Fibrotic Therapy
If regulatory approval is granted, nebulized Tyvaso could become the first and only inhaled antifibrotic therapy for patients with idiopathic pulmonary fibrosis. Current antifibrotic treatments are administered orally and are often associated with systemic side effects. An inhaled therapy designed to deliver medication directly to lung tissue could offer a novel alternative that complements existing treatment strategies.
Researchers believe that Tyvaso’s unique antifibrotic mechanism, combined with clinical observations of improved lung function, supports its potential role as a first-line inhaled treatment for fibrotic lung disease. The inhaled delivery method allows the drug to reach lung tissue directly, which may contribute to its observed effectiveness.
Characteristics of the Study Population
The TETON-2 trial included a total of 597 patients with idiopathic pulmonary fibrosis from multiple international sites. Participants were randomly assigned to receive either nebulized Tyvaso or placebo over a 52-week period. The study population reflected the characteristics of a typical IPF patient population.
The average age of participants was approximately 71.7 years, and about 80% of the patients were male. Baseline lung function measurements showed a mean predicted FVC of 76.8%. Notably, more than three-quarters of participants were already receiving background antifibrotic therapy at the time of enrollment, illustrating the advanced treatment context in which the study was conducted.
Safety and Tolerability
Treatment with nebulized Tyvaso was generally well tolerated. The safety profile observed in the TETON-2 trial was consistent with findings from earlier studies of the therapy and aligned with known prostacyclin-related side effects.
The most commonly reported adverse events included cough, headache, and diarrhea. Most of these side effects were mild to moderate in severity and manageable within the clinical setting. Importantly, researchers reported that no new safety signals emerged during the trial, supporting the overall safety profile of the therapy.
Next Steps for Regulatory Approval
Based on the encouraging results from the TETON-2 trial, United Therapeutics plans to submit a supplemental New Drug Application (sNDA) to the U.S. Food and Drug Administration in the second half of 2026. The submission will seek approval to expand the labeled indications for Tyvaso to include the treatment of idiopathic pulmonary fibrosis.
The regulatory application will also incorporate findings from the ongoing TETON-1 study, which is evaluating nebulized Tyvaso in IPF patients in the United States and Canada. Results from this trial are expected soon and will provide additional evidence supporting the therapy’s potential benefits.
Both the U.S. FDA and the European Medicines Agency have granted orphan drug designation for treprostinil for the treatment of IPF. This designation is intended to encourage the development of therapies for rare diseases by providing regulatory incentives and support.
The Broader TETON Clinical Program
The TETON-2 study is part of a broader clinical development initiative known as the TETON program. This program was initiated after a post-hoc analysis of the INCREASE trial suggested that Tyvaso may improve forced vital capacity in patients with pulmonary hypertension associated with interstitial lung disease.
Building on those observations, researchers designed the TETON clinical program to evaluate the potential of Tyvaso as a treatment for fibrotic lung diseases. The program includes multiple studies, each examining the therapy’s effectiveness in different patient populations.
The TETON-1 trial focuses on patients with IPF in the United States and Canada, while TETON-2 evaluated patients outside those regions. Another ongoing study, TETON-PPF, is investigating the use of Tyvaso in patients with progressive pulmonary fibrosis worldwide.
Study Design and Methodology
The TETON-2 trial was a randomized, double-blind, placebo-controlled Phase 3 study conducted across numerous countries, including Argentina, Australia, Belgium, France, Germany, Italy, Mexico, Spain, South Korea, Taiwan, and others. The study achieved full enrollment in July 2024.
Participants were randomly assigned in a 1:1 ratio to receive either nebulized Tyvaso or placebo. Treatment began with three inhaled breaths administered four times daily. Over time, doses were gradually increased until patients reached a target regimen of 12 breaths four times daily or the maximum dose they could tolerate.
The primary endpoint of the study was the change in absolute forced vital capacity from baseline to week 52. Secondary endpoints included time to clinical worsening, time to the first acute exacerbation of IPF, overall survival at week 52, changes in percent predicted FVC, quality-of-life assessments using the K-BILD questionnaire, and changes in diffusion capacity of the lungs.
Safety monitoring included evaluations of adverse events, serious adverse events, laboratory results, vital signs, and electrocardiogram measurements.
Long-Term Follow-Up Research
Patients who completed the TETON-2 study were eligible to participate in an ongoing open-label extension study known as TETON-OLE. This extension study is designed to evaluate the long-term safety and tolerability of nebulized Tyvaso in patients with fibrotic lung diseases.
By continuing to monitor participants over an extended period, researchers hope to better understand the therapy’s durability, long-term safety profile, and potential role in the future management of fibrotic lung conditions.
A Potential Shift in IPF Treatment
The publication of the TETON-2 results marks a significant step forward in the search for new treatments for idiopathic pulmonary fibrosis. By demonstrating that an inhaled therapy can slow disease progression and improve key clinical outcomes, the study offers hope for expanding therapeutic options for patients facing this life-threatening disease.
If approved by regulators, nebulized Tyvaso could represent a major advancement in the treatment of IPF, offering physicians and patients a new inhaled approach designed to directly target lung fibrosis while potentially improving lung function and quality of life.
About IPF
Idiopathic pulmonary fibrosis, or IPF, is a scarring disease of the lungs of an unknown (idiopathic) cause and is the most common of the idiopathic interstitial pneumonias. IPF is characterized by the progressive loss of the ability of the lungs to transfer oxygen into the blood, ultimately resulting in respiratory failure and death. While the precise causes of IPF remain unknown, IPF rarely presents before age 50 and can be associated with cigarette smoking and certain genetic dispositions. In addition, some evidence suggests that gastroesophageal reflux (acid reflux, or heartburn), certain viral infections, air pollution, and workplace exposures may be risk factors for IPF. IPF is estimated to affect between 0.33 and 4.51 people per 10,000 persons worldwide. Further, United Therapeutics estimates there are over 100,000 IPF patients in the United States.
About Tyvaso® (treprostinil) Inhalation Solution
INDICATION
TYVASO (treprostinil) Inhalation Solution is a prostacyclin mimetic indicated for the treatment of:
- Pulmonary arterial hypertension (PAH; WHO Group 1) to improve exercise ability. Studies with TYVASO establishing effectiveness predominately included patients with NYHA Functional Class III symptoms and etiologies of idiopathic or heritable PAH (56%) or PAH associated with connective tissue diseases (33%).
The effects diminish over the minimum recommended dosing interval of 4 hours; treatment timing can be adjusted for planned activities.
While there are long-term data on use of treprostinil by other routes of administration, nearly all clinical experience with inhaled treprostinil has been on a background of an endothelin receptor antagonist (ERA) and/or a phosphodiesterase type 5 (PDE-5) inhibitor. The controlled clinical experience with TYVASO was limited to 12 weeks in duration.
- Pulmonary hypertension associated with interstitial lung disease (PH-ILD; WHO Group 3) to improve exercise ability. The study with TYVASO establishing effectiveness predominately included patients with etiologies of idiopathic interstitial pneumonia (IIP) (45%) inclusive of idiopathic pulmonary fibrosis (IPF), combined pulmonary fibrosis and emphysema (CPFE) (25%), and WHO Group 3 connective tissue disease (22%).
