Shares of Insmed Incorporated (NASDAQ:INSM) climbed 6.6% on Monday after the company reported positive topline data from its Phase 3b ENCORE clinical trial evaluating ARIKAYCE.
The study achieved its primary endpoint as well as all multiplicity-controlled secondary culture conversion endpoints, showing statistically significant improvements in both respiratory symptom scores and culture conversion rates. Patients receiving ARIKAYCE alongside multidrug therapy recorded a 3.11-point improvement in respiratory symptom score at month 13 compared with those receiving placebo plus multidrug therapy, with a p-value of 0.0299.
The trial compared ARIKAYCE combined with multidrug therapy against placebo combined with multidrug therapy in patients experiencing a new case of Mycobacterium avium complex lung infection who had not previously been treated with antibiotics. Culture conversion by month 6 was achieved in 87.8% of patients treated with ARIKAYCE, versus 57.0% in the placebo group — a difference of 30.8 percentage points. Sustained culture conversion at month 15 reached 76.2% in the ARIKAYCE group compared with 47.6% for the placebo group.
The drug’s safety profile was consistent with previously known data, and no new safety concerns were identified. The most common treatment-emergent side effects reported more frequently in the ARIKAYCE group included dysphonia (58.7%), cough (32.9%) and fatigue (17.4%). Treatment discontinuation occurred in 18.3% of patients receiving ARIKAYCE compared with 11.8% in the control group.
Insmed said it intends to submit a supplemental new drug application to the U.S. Food and Drug Administration in the second half of 2026 to support a potential expansion of the drug’s label and to seek traditional approval for the existing refractory indication. The company also plans to file the trial data with Japan’s Pharmaceuticals and Medical Devices Agency during the same period.
According to the company, the ENCORE study fulfills a post-marketing requirement set by the FDA for ARIKAYCE.