Why Is Insmed Stock Falling Thursday?

Core Viewpoint - Insmed Incorporated's stock experienced a significant decline following the release of disappointing results from the Phase 2b BiRCh study of brensocatib for chronic rhinosinusitis without nasal polyps (CRSsNP) [2][8]. Study Results - The Phase 2b BiRCh study did not meet its primary or secondary efficacy endpoints for both the 10 mg and 40 mg treatment arms, indicating a lack of treatment benefit [2][4]. - The study reported the following least squares (LS) mean changes in the primary endpoint: placebo at -2.44, brensocatib 10 mg at -2.21, and brensocatib 40 mg at -2.33, showing minimal improvement [5]. Development Program Update - Insmed has decided to discontinue the development program for brensocatib in CRSsNP effective immediately and plans to present the study data at a future congress [3][4]. New Acquisition - Insmed acquired INS1148, an investigational monoclonal antibody aimed at treating respiratory and immunological diseases, with plans to advance its Phase 2 development in interstitial lung disease and moderate-to-severe asthma [6]. Analyst Insights - Analysts noted the inherent clinical risks associated with the BiRCh study due to the lack of prior data on DPP1 inhibition in CRSsNP [7]. - Despite the setback with CRSsNP, analysts believe that Brinsupri will have a strong market launch for bronchiectasis, and other lead programs like Arikayce and TPIP present meaningful expansion opportunities [7]. - RBC Capital has lowered its price target for Insmed from $215 to $195 while maintaining an Outperform rating, and Guggenheim has also lowered its price target from $230 to $221 while keeping a Buy rating [8]. Stock Performance - Following the news, Insmed's stock fell by 15.28%, trading at $168.14 at the time of publication [8].