Insmed shares surge 5.87% intraday after positive ENCORE trial data supports Arikayce label expansion in MAC lung disease.

Insmed surged 5.87% intraday following positive Phase IIIb ENCORE trial results for Arikayce in treating newly diagnosed MAC lung infections. The study met its primary endpoint, showing a 3.11-point improvement in respiratory symptom scores at Month 13 compared to placebo, alongside an 82.4% culture conversion rate versus 55.6% in the placebo group. These results position Arikayce for potential label expansion into earlier treatment lines in the U.S. and Japan, with a supplemental NDA filing planned for H2 2026. Jefferies and William Blair analysts highlighted the data’s significance in expanding Arikayce’s market and addressing prior concerns about the patient-reported outcome endpoint. The news, coupled with Stifel’s upgraded price target and broader valuation optimism, fueled the intraday rally.