Insmed’s Drug for Rare Lung Disease Achieves ‘home Run’ in Mid-stage Trial

(Reuters) -Insmed said on Tuesday that its experimental drug significantly reduced blood pressure in the lungs and improved exercise capacity in patients in a mid-stage study, lifting its shares up as much as 30%.

The potential success of the inhaled drug, treprostinil palmitil, would set Insmed on track to compete with larger rival Merck’s injectable treatment Winrevair and offer a convenient treatment option for patients.

Leerink Partners analyst Joseph Schwartz said the data is “prostanoid of choice for patients.”

The 102-patient study found that the drug helped reduce blood pressure in the patients’ lungs by 35%, compared with a placebo.

It also helped improve the patients’ ability to walk by an average of 35.5 meters and reduced levels of a protein associated with heart stress by 60%.

Coughing was reported as an adverse event in 40.6% of patients receiving the drug. However Guggenheim analyst Vamil Divan said it was “within the range of what should be expected” for an inhaled product.

The company plans to discuss the data with the U.S. Food and Drug Administration and initiate a late-stage trial for the drug in patients with pulmonary arterial hypertension (PAH) — a rare disease caused by a constriction of arteries in the lungs, leading to high blood pressure – in early 2026.

Around 1,000 new cases of PAH are diagnosed each year in the U.S., according to the American Lung Association.

RBC Capital Markets analyst Leonid Timashev said the data “comes in well above set bars” and as “our perceived home-run scenario,” estimating peak sales of $1.8 billion for the drug by 2034.

Current PAH treatments include Merck’s injectable Winrevair, Liquidia’s inhaled Yutrepia and United Therapeutics’ Tyvaso.

Liquidia and United Therapeutics’ PAH drugs “have sometimes been a challenge for patients to use” due to their safety concerns, Timashev added.

Shares of Liquidia and United Therapeutics were down over 23% and 16%, respectively.

Merck’s Winrevair, acquired through its $11.5 billion Acceleron Pharma purchase in 2021, generated $419 million in sales in 2024.

(Reporting by Kamal Choudhury in Bengaluru; Editing by Maju Samuel)