Insmed Incorporated (NASDAQ: INSM) announced that its Phase 3b ENCORE study of ARIKAYCE met its primary endpoint and all secondary endpoints for treating patients with Mycobacterium avium complex lung disease.

The study evaluated ARIKAYCE plus multidrug therapy versus placebo plus multidrug therapy in 425 patients with newly diagnosed MAC lung infection who had not received prior antibiotic treatment. The trial showed a statistically significant improvement in respiratory symptom scores at 13 months, with patients receiving ARIKAYCE achieving 17.77 points improvement compared to 14.66 points for placebo patients.

Culture conversion rates demonstrated substantial differences between treatment groups. By month 6, 87.8% of ARIKAYCE patients achieved culture conversion compared to 57.0% of placebo patients. At month 12, rates were 84.7% versus 61.3%, and durable culture conversion at month 15 was achieved by 76.2% of ARIKAYCE patients versus 47.6% of placebo patients.

The safety profile remained consistent with known side effects of ARIKAYCE. The most common treatment-emergent adverse events occurring more frequently in the ARIKAYCE group included dysphonia (58.7% versus 8.5%), cough (32.9% versus 14.6%), and dyspnea (16.4% versus 5.7%). Treatment discontinuation occurred in 18.3% of ARIKAYCE patients compared to 11.8% in the comparator group.

Based on these results, Insmed plans to file a supplemental new drug application with the FDA in the second half of 2026 to support potential label expansion for ARIKAYCE in MAC lung disease patients. The company also intends to submit data to Japan's Pharmaceuticals and Medical Devices Agency for potential label changes in that market.

ARIKAYCE is currently approved in the United States, Europe, and Japan for treating refractory MAC lung disease in patients who have not achieved negative sputum cultures after at least six months of multidrug therapy.