The Food and Drug Administration has accepted United Therapeutics' application to add idiopathic pulmonary fibrosis (IPF) to the approved uses of nebulized Tyvaso, starting a review the company expects to be completed in late April 2027. The company's announcement of the FDA filing acceptance, issued September 2, stressed that the inhaled drug has not been approved for IPF and remains investigational for that use.
Acceptance is a procedural step, not a verdict. It means the FDA considers the supplemental new drug application complete enough to review. The late April timeline is the company's stated expectation, and the agency could approve the drug, request more information, or decline to approve it.
United Therapeutics estimates that at least 100,000 people in the United States are living with IPF, a disease with few treatment options. "Current FDA-approved treatments for IPF are oral antifibrotic therapies," the company's chief medical officer, Dr. Franck Rahaghi, told Healio. If approved, the company says, nebulized Tyvaso would be the first inhaled antifibrotic treatment for the disease.
A Lung Disease with Limited Treatment Choices
IPF causes progressive scarring of the lungs from an unknown cause, gradually reducing the lungs' ability to move oxygen into the blood and ultimately leading to respiratory failure. It rarely appears before age 50 and can be associated with cigarette smoking and certain genetic factors, according to the company. Acid reflux, some viral infections, air pollution, and workplace exposures may also be risk factors.
Tyvaso, an inhaled form of treprostinil, is already approved to treat pulmonary arterial hypertension and pulmonary hypertension associated with interstitial lung disease. Both the FDA and the European Medicines Agency have granted treprostinil orphan designation for IPF, a status for rare diseases that carries development incentives.
The IPF program grew out of an earlier trial, called INCREASE, in patients with pulmonary hypertension and interstitial lung disease. A post-hoc analysis of that study suggested the drug was associated with improved lung function, which led the company to launch the TETON trials.
Because IPF mainly affects older adults, many patients already take other medications. Tyvaso's prescribing information warns that using it with diuretics, blood pressure drugs, or other vasodilators may increase the risk of symptomatic low blood pressure, so a full medication review would matter for anyone considering it.
Trial Results and Their Limits
The application rests on two phase 3, randomized, double-blind, placebo-controlled trials that each ran 52 weeks. TETON-1 enrolled patients in the United States and Canada, and TETON-2 enrolled patients in other countries. In a combined analysis published in The New England Journal of Medicine, nebulized Tyvaso outperformed placebo by 111.8 milliliters on the change in forced vital capacity, a standard measure of how much air a person can forcefully exhale after a deep breath (95% confidence interval, 79.7 to 144.0 mL).
The company reported that the drug also reached statistical significance on most key secondary goals, including a lower risk of clinical worsening and of acute IPF flare-ups, along with changes in a quality-of-life questionnaire and a measure of how well the lungs transfer gas. In the pooled data, 29.5% of patients on the drug had a clinical worsening event, defined as death from any cause, a respiratory-related hospitalization, or a relative decline of at least 10% in percent-predicted forced vital capacity, compared with 41.8% on placebo, Healio reported. The company described the trial population as broadly treated with background IPF therapy.
The evidence has important limits. Forced vital capacity measures lung function, not survival, and overall survival at week 52, a secondary endpoint, was not among the results the company listed as statistically significant. The trials were sponsored by United Therapeutics, and TETON-OLE, an open-label extension that allows eligible trial completers to continue treatment, is still evaluating long-term safety.
Safety questions also carry over from the drug's existing uses. Tyvaso's prescribing information warns of possible bronchospasm, low blood pressure, and a higher risk of bleeding. In an earlier 12-week trial in pulmonary arterial hypertension, cough was reported by 54% of Tyvaso patients compared with 29% on placebo, and headache by 41% compared with 23%.
Patients Weighing Their Options Now
Nothing changes for IPF patients today. People taking an oral antifibrotic should not stop or change treatment because of this review, and anyone curious about inhaled treprostinil should discuss it with a pulmonologist. Insurance coverage for an unapproved use can be difficult to obtain, so an FDA decision may matter for access as much as for prescribing. Nebulized Tyvaso is given with a dedicated inhalation device, so patients who eventually use it would need training on the system.
Patients and caregivers should watch for worsening shortness of breath, a persistent dry cough, fatigue, or reduced exercise tolerance, and report changes promptly. Seek emergency care for sudden severe breathlessness, chest pain, bluish lips, or confusion, which can signal a serious problem such as an acute flare.
Clinical trials remain another path. United Therapeutics said in the company's TETON-PPF enrollment update that enrollment is complete in its study of the drug in progressive pulmonary fibrosis, a related condition that the company says affects about 200,000 Americans. It expects topline results in the second half of 2027. The Pulmonary Fibrosis Foundation's page on inhaled treprostinil is a useful starting point for families comparing investigational options, and the foundation's help center can be reached at 844-825-5733.
Key questions remain open, including how the FDA will weigh the lung function data, what long-term safety looks like in IPF, and what the drug would cost for this use. The next milestone is the agency's decision, which United Therapeutics expects in late April 2027. MedicalDaily will report the outcome and any label details when they are released.
An established lung drug has moved a formal step closer to a possible new use. Patients with IPF should continue current treatment and use the months ahead to discuss options with their care team.
Key Questions Answered
What did the FDA do? The FDA accepted United Therapeutics' supplemental new drug application to add idiopathic pulmonary fibrosis to Tyvaso's approved uses. The company announced the acceptance on September 2.
Is Tyvaso approved for IPF? No. It is approved for pulmonary arterial hypertension and pulmonary hypertension associated with interstitial lung disease. It remains investigational for IPF.
When is a decision expected? United Therapeutics expects the FDA's review to be complete in late April 2027.
What did the trials show? A combined analysis of two phase 3 trials found that nebulized Tyvaso outperformed placebo by 111.8 mL on the change in forced vital capacity over 52 weeks and met most key secondary goals.
What are the known side effects? Tyvaso's prescribing information lists risks including bronchospasm, low blood pressure, and bleeding. Cough, headache, and throat irritation were common in an earlier pulmonary arterial hypertension trial.
What should IPF patients do now? Continue current treatment, talk with a pulmonologist about options, and seek emergency care for sudden severe breathlessness, chest pain, or confusion.
