BRIDGEWATER, N.J., July 16, 2026
Insmed Incorporated has announced positive 12-month results from the ongoing open-label extension (OLE) study evaluating treprostinil palmitil inhalation powder (TPIP) in patients with pulmonary arterial hypertension (PAH), reinforcing the investigational therapy’s potential to become a once-daily prostanoid treatment for this life-threatening rare disease. The long-term clinical data demonstrated sustained improvements across all major secondary efficacy endpoints, including exercise capacity, functional status, biomarker reduction, and REVEAL Lite 2.0 mortality risk scores, while maintaining a favorable safety and tolerability profile with no newly identified safety signals through 12 months. Importantly, patients who transitioned from placebo to TPIP achieved outcomes comparable to those receiving continuous TPIP treatment, highlighting the therapy’s consistent clinical benefit. These findings further strengthen the scientific rationale for the company’s ongoing Phase 3 PALM-PAH trial, positioning TPIP as a promising next-generation inhaled therapy for patients living with pulmonary arterial hypertension.
Long-Term Clinical Results Demonstrate Sustained Efficacy
The 24-month open-label extension study enrolled patients who previously completed Insmed’s Phase 2b PAH trials and evaluated the long-term safety, tolerability, and effectiveness of once-daily TPIP. After 12 months of treatment, patients receiving TPIP experienced a mean improvement of more than 55 meters in six-minute walk distance (6MWD), a clinically meaningful indicator of exercise capacity. Levels of NT-proBNP, an important biomarker of cardiac stress, were reduced by approximately 60%, while nearly 80% of patients achieved World Health Organization Functional Class I or II, reflecting improved disease status. Additionally, approximately 65% of participants reached REVEAL Lite 2.0 Refined Low Risk status, a prognostic marker associated with substantially lower mortality and disease progression risk. Patients who crossed over from placebo demonstrated improvements similar to those receiving continuous TPIP therapy, supporting the reproducibility of the treatment effect across study populations.
Safety Profile Supports Advancement into Phase 3 Development
The study also confirmed that TPIP remained safe and well tolerated throughout the first year of treatment, with no newly identified safety concerns despite dose escalation up to 1,280 µg once daily. Treatment-emergent adverse events were generally consistent with expectations for patients with advanced pulmonary arterial hypertension, and no deaths observed during the study were considered treatment related. The favorable balance between efficacy and safety provides strong support for continued development of TPIP as a differentiated inhaled prostanoid therapy. Based on these encouraging findings, Insmed continues to advance the Phase 3 PALM-PAH trial, a randomized, double-blind, placebo-controlled study designed to further evaluate TPIP’s ability to improve exercise capacity, functional outcomes, and overall clinical benefit in patients with PAH. The once-daily administration schedule also offers the potential to improve treatment adherence and patient convenience compared with currently available prostanoid therapies.
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TPIP Strengthens Insmed’s Rare Disease Pipeline
Pulmonary arterial hypertension remains a progressive and potentially fatal disease characterized by narrowing of the pulmonary arteries, leading to increased pressure on the heart and declining exercise tolerance. Although current therapies have improved patient outcomes, many individuals continue to experience disease progression despite treatment. TPIP, a proprietary dry powder formulation developed entirely within Insmed, is designed to deliver sustained prostanoid activity through convenient once-daily inhalation, representing a significant innovation in pulmonary vascular medicine. Beyond PAH, the investigational therapy is also being evaluated for pulmonary hypertension associated with interstitial lung disease (PH-ILD), progressive pulmonary fibrosis (PPF), and idiopathic pulmonary fibrosis (IPF), expanding its potential clinical impact across multiple serious respiratory disorders. The positive 12-month findings reinforce Insmed’s leadership in rare pulmonary diseases and provide growing evidence that TPIP could become an important new therapeutic option pending successful completion of Phase 3 development and future regulatory review.
Source: Insmed press release
