Insmed Incorporated announced the termination of its Phase 2b chronic rhinosinusitis without nasal polyps (CRSsNP) program for brensocatib after the study failed to meet its primary or secondary efficacy endpoints. The company also disclosed the acquisition of INS1148, a Phase 2‑ready monoclonal antibody, as part of its broader pipeline strategy.
The Phase 2b BiRCh study enrolled 288 patients across 104 sites worldwide. The primary endpoint was the 28‑day average of the daily sinus total symptom score (sTSS) at week 24. The least‑squares mean sTSS was –2.44 for placebo, –2.21 for the 10 mg dose, and –2.33 for the 40 mg dose, none of which differed significantly from placebo. Brensocatib was well tolerated, with no new safety signals reported.
The discontinuation removes a potential revenue source in the sinus disease market, estimated to be worth several hundred million dollars annually. Insmed’s focus will shift more heavily toward its existing indications—non‑cystic fibrosis bronchiectasis (for which brensocatib is already approved) and pulmonary hypertension—while the INS1148 acquisition adds a promising candidate for respiratory, immunologic, and inflammatory diseases, potentially expanding the company’s portfolio into interstitial lung disease and moderate‑to‑severe asthma.
Financially, Insmed remains unprofitable, reporting a net loss of $235.5 million in Q4 2024 and a net loss of $1.75 per share in Q3 2025, both below analyst expectations. Revenue beat expectations in both quarters, driven by strong demand for its approved products, but the company’s negative EBITDA of $978.79 million underscores ongoing cost pressures. Insmed raised its full‑year 2025 ARIKAYCE revenue guidance to $420–$430 million, reflecting confidence in that asset’s commercial trajectory. The terms of the INS1148 acquisition were not disclosed.
Insmed’s management highlighted the disappointment of the CRSsNP results but emphasized the clarity it provides for future strategy. Chief Medical Officer Martina Flammer noted that the data “provides a clear answer,” while CEO Will Lewis underscored the company’s commitment to executing strategic initiatives and advancing its pipeline. Analysts have responded by adjusting price targets, but they also recognize the strength of Insmed’s other assets, suggesting that the company’s long‑term prospects remain anchored by its approved therapies and pipeline breadth.
The termination of the brensocatib CRSsNP program illustrates the inherent risk of expanding a drug’s indication portfolio, yet the acquisition of INS1148 and the continued focus on bronchiectasis and pulmonary hypertension position Insmed to sustain growth in its core therapeutic areas while exploring new opportunities. Investors will need to reassess the company’s revenue potential and pipeline valuation in light of this development.
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