Insmed disclosed that Brinsupri (brensocatib) failed a Phase 2b trial in chronic rhinosinusitis without nasal polyps, ending a run of positive results that had elevated the company’s valuation. The negative readout prompted a sharp share price drop and prompted management to refocus pipeline priorities. Separately, a clinical report noted a Brinsupri setback that cut Insmed’s market capitalization, underscoring how single trial outcomes can swing mid‑cap biotech valuations. Insmed said it will discontinue development in that nasal indication but announced acquisition of a Phase‑ready monoclonal antibody (INS1148) to bolster its respiratory and inflammatory pipeline. The episode reinforces investor sensitivity to expansion trials and the need for diversified clinical assets. Companies and investors will reassess go‑to‑market assumptions for Brinsupri in other indications and monitor the development trajectory for INS1148.