TOPLINE:

Among patients with idiopathic pulmonary fibrosis, inhaled treprostinil was associated with a smaller decline in forced vital capacity (FVC) and fewer episodes of clinical worsening than placebo over 52 weeks.

METHODOLOGY:

• Researchers conducted a phase 3 randomized trial to evaluate the efficacy and safety of inhaled treprostinil over 52 weeks among patients with idiopathic pulmonary fibrosis.
• A total of 593 patients (mean age, 71.7 years; 80.1% men) received either inhaled treprostinil (n = 298) or placebo (n = 295), both administered four times daily over 52 weeks; all patients had a baseline FVC of at least 45% of the predicted value.
• The treprostinil dose was initiated at 3 breaths (18 µg) and subsequently titrated up to 12 breaths (72 µg).
• The primary endpoint was the change in absolute FVC from baseline to week 52; secondary endpoints included clinical worsening and acute exacerbations over the same period.
• Safety endpoints, including adverse events, were assessed.

TAKEAWAY:

• At week 52, the median change in FVC was -49.9 mL with treprostinil and -136.4 mL with placebo, with a between-group difference of 95.6 mL (P < .001), indicating a significant smaller decline in lung function with treprostinil.
• Treprostinil was associated with a reduced risk for clinical worsening compared with placebo (hazard ratio, 0.71; P = .02); the time to first acute exacerbation was similar between the groups.
• Cough was the most common adverse event, occurring in 48.3% of patients on treprostinil compared with 24.1% on placebo; severe adverse events occurred in 25.2% of patients in the treprostinil group and 23.1% in the placebo group.

IN PRACTICE:

“In this trial, inhaled treprostinil was associated with a smaller decline in FVC and fewer clinical-worsening events than placebo over a period of 52 weeks in patients with IPF [idiopathic pulmonary fibrosis],” the authors wrote.

SOURCE:

The study was led by Steven D. Nathan, MD, Inova Fairfax Hospital, Falls Church, Virginia. It was published online on March 11, 2026, in The New England Journal of Medicine.

LIMITATIONS:

Many patients stopped treatment early in both groups. The trial was not adequately powered to assess efficacy in specific subgroups, notably in patients receiving background antifibrotic therapy vs those not receiving it. Moreover, the 52-week duration was insufficient to evaluate long-term mortality outcomes.

DISCLOSURES:

The trial was funded by United Therapeutics. Five authors reported being employees of the company, and two reported holding stock. Several authors disclosed having relationships — including receiving consulting fees, serving in advisory roles, receiving lecture honoraria, participating in clinical trials, or serving on data monitoring boards — with pharmaceutical companies.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.