Insmed Reports Positive Phase 2b Results for Inhaled PAH Treatment TPIP

Insmed has announced favorable outcomes from its phase 2b clinical trial assessing treprostinil palmitil inhalation powder (TPIP) in patients with pulmonary arterial hypertension (PAH). The investigational therapy, developed as a prodrug of United Therapeutics’ treprostinil (Tyvaso), is formulated for once-daily administration using a capsule-based inhalation device.
The mid-stage study enrolled 102 participants and achieved both its primary and secondary endpoints. The treatment resulted in a 35% placebo-adjusted reduction in pulmonary vascular resistance (PVR) and an average improvement of 35.5 meters in six-minute walk distance. These metrics are key indicators in assessing treatment efficacy for PAH, a condition characterized by elevated blood pressure in the pulmonary arteries due to vessel narrowing or obstruction.

In addition to these findings, TPIP was observed to lower levels of a protein linked to heart stress by 60%. The most common adverse event reported was coughing, affecting 40.6% of participants receiving the drug. Guggenheim analyst Vamil Divan commented that this frequency is “within the range of what should be expected” for an inhaled formulation.
Insmed stated that it will proceed with regulatory engagement to design a phase 3 trial. The company intends to begin a phase 3 study for PAH patients in early 2026. Another study targeting patients with pulmonary hypertension associated with interstitial lung disease (PH-ILD) is planned before the end of 2025.
Gene Sullivan, M.D., Insmed’s Chief Product Strategy Officer, remarked, “The statistically significant and clinically meaningful results shown with TPIP in pulmonary arterial hypertension mark a potential breakthrough for patients and the future of prostanoid therapy.”
The trial’s results have implications for the current competitive landscape. TPIP’s data were considered strong relative to expectations, which had set the threshold for success at a 20% PVR improvement and a 15- to 20-meter gain in walking distance. Jefferies analyst Kelly Shi, Ph.D., noted prior to the readout that achieving those levels might prompt a shift from Tyvaso to TPIP.
RBC Capital Markets analyst Leonid Timashev assessed the outcome as exceeding established benchmarks, estimating peak annual sales of $1.8 billion by 2034. He also stated that the results reflect “our perceived home-run scenario.”
The share price of Insmed rose sharply following the announcement. On Tuesday morning, it traded at approximately $89, up from $70 at the previous day’s close—an increase of more than 27%. The company reported that the inhaled therapy significantly reduced pulmonary blood pressure and improved exercise capacity.

TPIP’s progress positions Insmed to compete with other approved PAH treatments, including Merck’s injectable Winrevair, which generated $419 million in sales in 2024. Additional market competitors include United Therapeutics’ Tyvaso and Liquidia’s inhaled Yutrepia. Following Insmed’s data release, shares of Liquidia and United Therapeutics declined by over 23% and 16%, respectively.