The study, “Inhaled Treprostinil in Pulmonary Hypertension Due to Interstitial Lung Disease,” was published in The New England Journal of Medicine.
ILD is a term that includes several conditions characterized by scarring (fibrosis) within the lungs. Often, ILD is complicated by pulmonary hypertension, or abnormally high pressure in the lung’s blood vessels.
Tyvaso, marketed by United Therapeutics, contains treprostinil, a vasodilator agent that works to widen blood vessels in the lungs to lower blood pressure. It is administered as an inhaled solution using a hand-held, portable device. The therapy is approved in the U.S. to treat pulmonary arterial hypertension (WHO Group 1 PH), but not PH-ILD (WHO Group 3).
In fact, no therapies are currently approved to treat PH-ILD.
Researchers in the U.S. analyzed the findings of the Phase 2/3 clinical trial (NCT02630316), called INCREASE, which over 16 weeks evaluated the safety and efficacy of Tyvaso (inhaled four times daily, up to 12 breaths per session) in people with PH-ILD compared with a placebo.
The study included 326 adults, 46.9% female, with a mean age of 66.5. In total, 163 patients were treated with Tyvaso and the other 163 received a placebo. From these, 40 patients in the Tyvaso (24.5%) group and 38 assigned to placebo (23.3%) did not complete treatment.
Researchers recorded patients’ six-minute walk distances (a standard measure of exercise capacity) and measured N-terminal pro B-type natriuretic peptide (NT-proBNP) levels — a prognostic marker of cardiovascular function.
Analysis showed a significant difference between the Tyvaso group and the placebo groups at week 16 regarding changes in walk distance from the study’s start — an increase of 21.08 meters over six minutes in those receiving Tyvaso, versus a 10.04-meter decrease in the placebo group.
Tyvaso-treated patients also showed significant improvements in cardiovascular function, with a reduction of 15% in NT-proBNP levels from study start, compared with an increase of 46% in the placebo group.
Over the 16-week study, significantly fewer cases of clinical worsening were recorded in patients on Tyvaso versus placebo (22.7 vs. 33.1%). Exacerbations, or flares in which disease symptoms suddenly get worse, (26.4 vs. 38.7%) and hospitalizations for a cardiopulmonary indication (11 vs. 14.7%) were also fewer across the Tyvaso group.
Most adverse events were mild or moderate in intensity. Commonly reported side effects included cough, headache, shortness of breath, dizziness, nausea, fatigue, and diarrhea, the researchers reported.
Notably, serious adverse events were not more frequent in the Tyvaso group (23.3%) than in the placebo group (25.8%).
The researchers noted several limitations to their study, including its short duration, a significant number of patients discontinuing the trial prematurely, and the fact that clinical evaluation was investigator-reported and not judged by an independent review committee.
Nonetheless, “among patients with pulmonary hypertension due to interstitial lung disease, treatment with inhaled treprostinil improved exercise capacity as shown by improvement in the 6-minute walk distance through the end of the 16-week treatment period,” the researchers concluded.
“In addition, treatment with inhaled treprostinil was associated with a lower risk of clinical worsening than that with placebo, a reduction in NT-proBNP levels, and fewer exacerbations of underlying lung disease,” they added.
Of note, this study was supported by United Therapeutics, and five of its 16 researchers are company employees.
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