Novartis DM1 drug flops in phase 3, clouding $12B Avidity deal

Novartis’ phase 3 Harbor trial of del-desiran failed to meet its primary endpoint in myotonic dystrophy type 1 (DM1), undermining the $12 billion acquisition of Avidity Biosciences and sending the stock lower in premarket trading. While some secondary signals were noted, the miss raises questions about del-desiran’s contribution to future sales; Novartis will review the full data with regulators to determine next steps. The company also continues with other Avidity assets—delpacibart zotadirsen for Duchenne and delpacibart braxlosiran for FSHD—pursuing next actions based on newer data and FDA discussions.