INSM Stock Plummets on Sinus Study Failure, Adds New Pipeline Asset

Core Insights - Insmed's shares fell nearly 20% in after-market trading following the failure of the mid-stage BiRCh study for Brinsupri in chronic rhinosinusitis without nasal polyps [1][7] - The BiRCh study did not meet its primary or secondary efficacy endpoints, leading to the decision to halt Brinsupri's development in this indication [2][7] - Investors were surprised by the negative results, especially after Insmed's recent success with Brinsupri's approval for non-cystic fibrosis bronchiectasis [3][6] Company Performance - Despite the setback, Insmed's shares are still up 187% year-to-date, significantly outperforming the industry average growth of 18% [6] - Brinsupri generated $28 million in sales during Q3 2025, indicating strong initial market uptake [4] - The failure of the BiRCh study has dampened investor enthusiasm for the ongoing phase II CEDAR study for Brinsupri in hidradenitis suppurativa, with results expected in the first half of 2026 [5] Pipeline Expansion - Insmed announced the acquisition of investigational monoclonal antibody INS1148 from Opsidio, aimed at treating respiratory and immunological diseases [9] - The company plans to develop INS1148 in mid-stage studies for interstitial lung disease and moderate-to-severe asthma [9]