TPIP trial exceeds expectations; Phase 3 studies to begin by early 2026
Shares in Insmed Incorporated (NASDAQ:INSM) closed 28.65% higher at US$90.93 on Tuesday, after the company announced positive topline results from a mid-stage trial of its inhaled therapy for pulmonary arterial hypertension (PAH), sending the stock to its highest level in nearly 25 years.
The Phase 2b study of treprostinil palmitil inhalation powder (TPIP) met its primary endpoint, delivering a placebo-adjusted 35% reduction in pulmonary vascular resistance with strong statistical significance (p<0.001). The drug also met all secondary endpoints, including a 35.5-meter improvement in six-minute walk distance and a 60% reduction in NT-proBNP levels, a biomarker of cardiac stress.
“These unprecedented Phase 2b results unequivocally demonstrate TPIP’s potential to be a highly effective and well-tolerated once-daily prostanoid therapy for the treatment of PAH across disease severities and background treatment regimens,” said Gene Sullivan, Insmed’s Chief Product Strategy Officer.
The therapy was generally well-tolerated. The most common side effects in TPIP-treated patients included cough (40.6%), headache (31.9%), and fatigue (10.1%), compared to 21.2%, 15.2%, and 3.0% respectively in the placebo group. Serious treatment-emergent adverse events (TEAEs) occurred in 7.2% of patients on TPIP versus 3.0% on placebo. No deaths occurred during the study.
A potential new competitor in the prostanoid space
Insmed’s once-daily dry powder formulation of treprostinil is a prodrug of Tyvaso, marketed by United Therapeutics (NASDAQ:UTHR). With the TPIP data exceeding the 20% PVR and 15–20m walking distance improvements analysts had set as likely benchmarks for a switch from Tyvaso, Insmed may now pose a competitive threat in the prostanoid market—particularly as United’s exclusivity on dry powder formulations expired in May.
Shares of United Therapeutics fell nearly 14% to around US$283, reflecting the potential disruption to its flagship Tyvaso DPI product, which achieved over US$1bn in sales in 2024.
Regulatory plans and market momentum
Insmed said it will immediately engage with the FDA regarding Phase 3 trial design for PAH. It plans to launch:
- A Phase 3 trial in pulmonary hypertension associated with interstitial lung disease (PH-ILD) by the end of 2025
- A separate Phase 3 trial in PAH patients in early 2026
According to the company, 84% of TPIP-treated patients were able to titrate to at least 480 µg once daily, and 75% reached the maximum dose of 640 µg, reinforcing the therapy’s durability as a once-daily treatment.
Investment firm Leerink Partners reiterated its Outperform rating on the stock with a US$100 price target, noting that the data exceeded even its “best-case scenario.”
Retail sentiment surged in response to the results, with message volume on social media platforms moving into “extremely bullish” territory.
A pivotal moment for Insmed
The data release marks a significant milestone for Bridgewater, New Jersey-based Insmed, which already markets Arikayce, an inhaled antibiotic for Mycobacterium avium complex lung disease that generated US$363mn in 2024 sales. With TPIP, the company is now positioning itself as a serious player in the PAH and PH-ILD space.
If the strong trial data translates into successful Phase 3 outcomes, Insmed could reshape a market currently dominated by United Therapeutics, and potentially provide patients with a simpler, once-daily alternative in a challenging disease area.
