Insmed reports positive 12-month data for investigational PAH therapy TPIP

Insmed announced 12-month safety and efficacy results from an ongoing open-label extension study of treprostinil palmitil inhalation powder for pulmonary arterial hypertension (PAH). The company hosted a conference call and webcast to discuss the data. This disclosure provides investors with an update on the clinical development progress of this investigational therapy.

The 12-month data from the ongoing open-label extension study showed sustained improvement across all secondary efficacy endpoints for TPIP in pulmonary arterial hypertension patients. Patients demonstrated meaningful gains in six-minute walk distance, significant reductions in NT-proBNP biomarker levels, improved WHO Functional Class status, and clinically meaningful improvement in REVEAL Lite 2.0 mortality risk scores. Notably, patients who switched from placebo to TPIP achieved similar outcomes to those who continued TPIP treatment.

The safety profile through 12 months showed TPIP was generally well tolerated with no newly identified safety signals at doses up to 1,280 µg once daily. While treatment-emergent adverse events were common, serious and severe events occurred in less than one-fifth of patients, and discontinuation rates were low. Four deaths occurred but were not considered treatment-related.

The positive 12-month OLE data support the continued clinical development of TPIP and the recent initiation of PALM-PAH, a Phase 3 randomized, double-blind, placebo-controlled trial evaluating once-daily TPIP in PAH patients over 24 weeks. The primary endpoint is change in six-minute walk distance, with additional assessments of safety, tolerability, and overall efficacy.

The 12-month interim analysis of the open-label extension study showed that patients continuing TPIP maintained improvements in exercise capacity (6-minute walk distance), cardiac stress biomarkers (NT-proBNP), functional class, and mortality risk scores. Patients who switched from placebo to TPIP achieved similar outcomes, suggesting consistent treatment effects. The study enrolled 91 patients from prior Phase 2 trials.

Insmed disclosed the status of its Phase 3 registrational program for TPIP across four indications: pulmonary arterial hypertension (PAH, enrollment progressing), pulmonary hypertension due to interstitial lung disease (PH-ILD, sites actively screening), progressive pulmonary fibrosis (PPF, initiation expected second half 2026), and idiopathic pulmonary fibrosis (IPF, initiation expected first half 2027). This represents a broad development strategy for the investigational drug.

Approximately 65% of patients achieved Refined Low Risk status (score ≤4, associated with <5% mortality at 1 and 3 years) by month 12. Patients continuing TPIP showed a mean 2.0-point improvement in REVEAL Lite 2.0 score, while those crossing from placebo showed a 1.4-point improvement. The REVEAL Lite 2.0 is a validated tool to estimate mortality and disease progression risk in PAH patients, where a 1-point improvement is associated with approximately 23% reduction in death risk.