Insmed Incorporated (Insmed (INSM)) on Thursday released 12-month results from the ongoing open-label extension (OLE) study of its once-daily inhaled drug, treprostinil palmitil inhalation powder (TPIP), in patients with pulmonary arterial hypertension (PAH). PAH is a rare, progressive disease where the tiny arteries in the lungs narrow, increasing blood pressure and forcing the heart to work harder.
The data showed sustained improvements across multiple efficacy measures, and patients who switched from placebo to TPIP saw similar benefits. That's a good sign as the company moves its Phase 3 PALM-PAH trial forward.
The OLE study is designed to assess long-term safety, tolerability, and effectiveness of TPIP over 24 months in patients who completed earlier TPIP PAH studies. It's not placebo-controlled — patients either continued TPIP or crossed over from placebo.
At the 12-month mark, patients who remained on TPIP (n=60) and those who switched from placebo (n=31) produced comparable outcomes across all major efficacy endpoints. Those continuing TPIP improved their six-minute walk distance by an average of 55.7 meters from baseline, while those crossing over from placebo improved by 54.1 meters.
Both groups also recorded roughly a 60% reduction in N-terminal fragment pro-B-type natriuretic peptide (NT-proBNP) concentrations — a biomarker for heart failure. That's a big deal: it suggests the drug is easing the heart's workload.
In addition, 78.3% of patients in the TPIP continued group and 80.6% in the placebo crossover group achieved World Health Organization Functional Class I or II by Month 12. More than one-quarter of patients across both groups reached Functional Class I — the best possible score.
The mean REVEAL Lite 2.0 score — a risk assessment tool — improved by 2.0 points in the TPIP continued group and 1.4 points among patients who switched from placebo. Approximately 65% of patients achieved Refined Low Risk status, which is associated with an estimated mortality risk of less than 5% over three years and about a 7% risk of clinical worsening within one year.
On the safety front, Insmed said once-daily TPIP remained generally well tolerated at doses up to 1,280 micrograms through Month 12, with no newly identified safety signals. The company said the findings support continued development of TPIP and the recently initiated Phase 3 PALM-PAH trial.
As for the stock: Insmed shares were down 3.67% at $105.77 at the time of publication on Thursday.
