Inhaled Treprostinil Slows Lung Function Decline

A combined analysis of two phase 3 trials found that inhaled treprostinil reduced forced vital capacity (FVC) loss over 52 weeks compared with placebo in adults with idiopathic pulmonary fibrosis (IPF). The findings were published in the American Journal of Respiratory and Critical Care Medicine.

The prespecified analysis pooled data from TETON-1 and TETON-2, randomized, double-blind, placebo-controlled trials. It included 1,191 participants who received treatment: 597 assigned to inhaled treprostinil and 594 to placebo. Approximately three quarters were receiving background nintedanib or pirfenidone. The primary endpoint was change in absolute FVC at week 52.

Median FVC declined by 45.4 mL with treprostinil and 161.7 mL with placebo, a between-group difference of 111.8 mL (95% CI, 79.7-144.0). Clinical worsening, a composite of all-cause death, respiratory hospitalization, or at least a 10% relative decline in percent-predicted FVC, occurred in 29.5% versus 41.8% (hazard ratio, 0.69; 95% CI, 0.57-0.84). Acute IPF exacerbations occurred in 3.2% versus 6.1% (hazard ratio, 0.52; 95% CI, 0.30-0.91).

Deaths occurred in 6.9% of treprostinil recipients and 9.4% of placebo recipients, a difference that was not statistically significant. Cough was reported in 51.6% versus 28.6%, and adverse events prompted treatment discontinuation in 18.8% versus 13.6%, respectively.

The investigators concluded that inhaled treprostinil slowed lung function loss and delayed clinical worsening over 52 weeks. They noted that 37.0% of treprostinil recipients and 28.8% of placebo recipients discontinued study treatment prematurely. Follow-up was limited to 52 weeks; longer-term evaluation is ongoing. United Therapeutics sponsored the studies.

Source: Nathan SD, Smith P, Deng C, et al. Combined results of the TETON-1 and TETON-2 trials of inhaled treprostinil for idiopathic pulmonary fibrosis. Am J Respir Crit Care Med. 2026. doi:10.1093/ajrccm/aamag507