Insmed reported a failed Phase 2b study of brensocatib (Brinsupri) in chronic rhinosinusitis, prompting a sell‑off that cut the company's market capitalization and ended a recent streak of positive clinical updates. The trial showed no benefit for the two tested doses, and management said it would stop pursuing that indication. Investors reacted sharply as the company had been building valuation momentum following regulatory approvals and stronger-than-expected sales in bronchiectasis. Insmed said it will pivot, adding a new monoclonal antibody asset, INS1148, slated for Phase 2 trials, to diversify its pipeline. The setback highlights the risk of indication expansion and the need for confirmatory proof in diseases lacking robust animal models. Insmed’s balance between near‑term commercial execution and pipeline diversification will shape investor confidence into 2026.