A post-hoc analysis of the phase 3 TETON-2 study, presented at the CHEST 2026 Annual Meeting in Phoenix, Arizona, found that inhaled treprostinil significantly reduced multiple disease progression events in patients with idiopathic pulmonary fibrosis (IPF).
Steven Nathan, MD, MBBCh, FCCP, Director of the Advanced Lung Disease and Lung Transplant Program at Inova Fairfax Hospital, discusses the findings and their implications for patients.
Understanding Idiopathic Pulmonary Fibrosis
IPF is a serious, rare chronic lung disease that causes the interstitium, the tissue around the alveoli in the lungs, to become thick, stiff, and permanently scarred. It affects about 13 to 21 per 100,000 people, with higher rates in North America.
Inhaled treprostinil is a synthetic prostacyclin analogue prescribed to relax and widen blood vessels in the lungs. It was previously approved for pulmonary hypertension associated with interstitial lung disease (PH-ILD).
Dr. Nathan noted that the TETON research program originated from observations in the INCREASE study (NCT02630316), which found that ILD patients who received inhaled treprostinil experienced favorable lung function outcomes. Those findings prompted additional research into the drug’s benefits for IPF.
TETON-2 Analysis Finds Fewer Disease Progression Events
The TETON-2 study (NCT05255991) is a multinational phase 3 clinical trial sponsored by United Therapeutics evaluating the safety and efficacy of inhaled treprostinil (Tyvaso) in patients with IPF. The study met its primary endpoint, demonstrating a smaller decline in forced vital capacity (FVC) among patients receiving inhaled treprostinil compared with placebo (49.9 mL versus 136.4 mL).
Dr. Nathan shared that unlike the original analysis, which evaluated the time until a patient’s first disease progression event, the post-hoc analysis presented at CHEST counted all qualifying progression events experienced by patients throughout the 52-week study.
The most notable finding was that there were 126 progression events among 82 patients receiving inhaled treprostinil compared to 161 progression events among 115 patients receiving placebo (P=0.003)1.
Dr. Nathan said the difference was largely driven by fewer relative declines of at least 10% in percent predicted FVC (56 versus 86 events) and fewer concurrent IPF exacerbations with respiratory hospitalizations (6 versus 18 events)1.
Why Multiple Progression Events Matter
Dr. Nathan shared that the post-hoc analysis provided a more complete picture of treatment outcomes by examining what happened after participants experienced their first progression event. He noted that even though some patients experienced progression while taking inhaled treprostinil, it doesn’t necessarily mean the medication stopped working.
He highlighted that among patients who experienced an initial progression event, there were 22 subsequent deaths in the inhaled treprostinil group compared with 44 in the placebo group.
Treatment Considerations and Clinical Implications
Dr. Nathan described the overall TETON findings as strong evidence demonstrating the potential benefits of inhaled treprostinil in patients with IPF. However, he acknowledged that the treatment doesn’t always prevent disease progression, and some patients experience side effects or discontinue treatment.
In the original TETON-2 study, cough was the most common adverse event. Dr. Nathan also noted that the four-times-daily nebulizer schedule could have contributed to treatment fatigue and discontinuation among some participants.
In Their Own Words
“If you do have progression on the drug, say a decline in FVC or hospitalization, it doesn’t mean that the drug is not working. It becomes added impetus to continue on the medication because you want to be in the good group and not the bad group.” – Steven Nathan, MD, MBBCh, FCCP, Director of the Advanced Lung Disease and Lung Transplant Program at Inova Fairfax Hospital
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To learn more about idiopathic pulmonary fibrosis and other rare lung diseases, visit: https://checkrare.com/diseases/lung-diseases/