Insmed's inhaled TPIP holds gains at 12 months, placebo group catches up
A 91-patient open-label extension showed sustained 6-minute walk, biomarker and functional-class benefits through Month 12, with patients who started on placebo matching the drug-treated group after crossing over.
Executive Summary
- Insmed reported that its inhaled prostacyclin-receptor agonist held its effect on walk distance, cardiac biomarkers and functional class through 12 months in an open-label extension of its Phase 2b pulmonary arterial hypertension study, with no new safety signals.
- Patients who had been on placebo in the earlier randomized study and switched to the drug in the extension caught up to the group that had been on treatment from the start, a result that strengthens the case that the effect is drug-driven rather than a placebo or selection artifact.
- Because the extension has no concurrent placebo arm, the 12-month figures are measured against pre-treatment baseline rather than against a matched control, so the readout adds durability evidence without adding a new controlled comparison.
- Insmed is using the extension data to support its move into a randomized Phase 3 program, the trial whose result will determine the drug's competitive standing among the established set of prostacyclin-pathway therapies in this disease.
The readout
Insmed announced 12-month data on July 16, 2026, from the ongoing open-label extension of NCT05649748, a non-placebo-controlled study that followed patients who completed the earlier Phase 2b TPIP trials in pulmonary arterial hypertension. Mean six-minute walk distance improved 55.7 meters from baseline in the group that stayed on TPIP throughout (N=60) and 54.1 meters in the group that started on placebo and crossed over (N=31). NT-proBNP, a marker of cardiac strain, fell by about 60% in both groups, with geometric mean ratios to baseline of 0.40 and 0.41. InsmedInsmed Announces Positive 12-Month Data from the Ongoing Open-Label Extension Study of Treprostinil Palmitil Inhalation Powder (TPIP) in Patients with Pulmonary Arterial HypertensionJul 16, 2026
Probability of SuccessBased on the AppliedXL Probability of Success model. For more information about the methodology, read the research here.
Functional class and risk score
78.3% of the TPIP-continued group and 80.6% of the placebo-crossed group reached WHO Functional Class I or II by Month 12, and more than a quarter of patients in both groups reached Class I. Mean REVEAL Lite 2.0 score, a composite risk tool used in pulmonary arterial hypertension, improved 2.0 points from baseline in the TPIP-continued group and 1.4 points in the placebo-crossed group. About 65% of all patients reached Refined Low Risk status on that score, a category the company's release ties to an estimated mortality risk under 5% at three years. Gene Sullivan, Insmed's Chief Product Strategy Officer, said the data show TPIP "demonstrated sustained improvement across all efficacy endpoints and was well tolerated with no newly identified safety signals". InsmedInsmed Announces Positive 12-Month Data from the Ongoing Open-Label Extension Study of Treprostinil Palmitil Inhalation Powder (TPIP) in Patients with Pulmonary Arterial HypertensionJul 16, 2026
Safety and design
The extension permitted doses up to 1,280 micrograms once daily, above the doses used in the lead-in randomized study, and safety through Month 12 showed no new safety signals against the drug's established profile. Insmed's own safety_profile characterization is 'consistent with known,' though the underlying treatment-emergent adverse event rate ran at 89.0% of patients, and four deaths occurring in the extension were assessed as unrelated to treatment. The study is open-label and non-placebo-controlled by design, built to track long-term tolerability and durability rather than to generate a new controlled efficacy comparison. Insmed+1Insmed Announces Positive 12-Month Data from the Ongoing Open-Label Extension Study of Treprostinil Palmitil Inhalation Powder (TPIP) in Patients with Pulmonary Arterial HypertensionJul 16, 2026An Extension Study of Treprostinil Palmitil Inhalation Powder (TPIP) for Pulmonary Arterial Hypertension (PAH)NCT05649748
The competitive setting
TPIP is a small-molecule IP-receptor agonist delivered by inhalation, competing in a prostacyclin-pathway class that already includes approved oral, inhaled and infused agents, alongside Insmed's own Phase 3 program for the same drug in pulmonary hypertension associated with interstitial lung disease, the closest direct comparator on record. Against a prostacyclin-pathway class that already has multiple approved routes of administration, the bar for TPIP's Phase 3 PALM-PAH study is separation on six-minute walk distance, the endpoint the company has said it changed the primary measure to for that trial, against the safety and dosing convenience of once-daily inhalation rather than multiple daily doses.
This analysis was produced using AI-assisted reporting systems, AppliedXL data, and official public records. These systems undergo editorial review, quality checks, and regular audits by human experts. Errors may still occur, as with any automated system. Always consult the linked primary sources. Read our AI Editorial Policy.