Insmed's Phase 3b ENCORE Study Of Arikayce Plus Multidrug Therapy Met Primary Endpoint In Patients With MAC Lung Disease, Filing Of FDA Application For Label Expansion For Arikayce Is Expected In 2H Of 2026

Insmed Incorporated (NASDAQ:INSM), a people-first global biopharmaceutical company striving to deliver first- and best-in-class therapies to transform the lives of patients facing serious diseases, today announced positive topline results from the Phase 3b ENCORE study. This study evaluated ARIKAYCE® (amikacin liposome inhalation suspension) plus multidrug therapy (azithromycin 250 mg + ethambutol 15 mg/kg) once-daily versus placebo plus multidrug therapy once-daily in diagnosed patients with a new occurrence of Mycobacterium avium complex (MAC) lung infection who had not received antibiotics.

Topline efficacy results from the ENCORE study are as follows:

"These results are an exciting win for patients living with MAC lung disease and a powerful validation of ARIKAYCE's ability to deliver real clinical benefit as part of a multidrug treatment regimen," said Martina Flammer, M.D., MBA, Chief Medical Officer of Insmed. "We are energized by the potential for patients with a new MAC infection to see benefit with ARIKAYCE earlier in their treatment journey and look forward to exploring the expansion of the ARIKAYCE indication in the U.S. and Japan, with the ultimate goal of improving outcomes for an even greater number of patients fighting this difficult disease."

With these results, Insmed has completed the study intended to fulfill the U.S. Food and Drug Administration (FDA) post-marketing requirement, further strengthening the clinical foundation supporting ARIKAYCE. Insmed plans to file a supplemental new drug application (sNDA) for ARIKAYCE in patients with MAC lung disease in the second half of 2026 to support potential label expansion and to obtain traditional approval for the existing refractory indication in the U.S. Additionally, Insmed plans to submit the data to the Pharmaceuticals and Medical Devices Agency (PMDA) in the second half of 2026 to support potential label expansion in Japan. Insmed also plans to present these data at a future medical congress.

"These groundbreaking results show that patients may have significant clinical benefit from including ARIKAYCE as part of their multidrug treatment earlier in their MAC lung disease journey," said David Griffith, M.D., ENCORE Steering Committee Member, Professor of Medicine, National Jewish Health. "The improvements in Respiratory Symptom Score alongside durable culture conversion highlight the potential for this medicine to make a substantial difference in outcomes for patients facing this serious and often progressive infection."

The safety profile was consistent with the known safety profile of ARIKAYCE, and no new safety signals were observed. The most common treatment-emergent adverse events (TEAEs) occurring in 10% or more of patients in a treatment arm and higher in the ARIKAYCE arm compared to the active comparator arm were in line with expectations. Overall TEAEs were as follows:

Among TEAEs of special interest, only bronchospasm (n=49, 23.0% vs n=25, 11.8%) and hypersensitivity pneumonitis (n=5, 2.3% vs n=0) occurred in notably more patients receiving ARIKAYCE than patients in the comparator arm. Comparable rates between treatment arms were observed for ototoxicity (n=55, 25.8% vs n=48, 22.6%), exacerbation of underlying pulmonary disease (n=23, 10.8% vs n=21, 9.9%), hemoptysis (n=22, 10.3% vs n=22, 10.4%), neuromuscular disorders (n=5, 2.3% vs n=6, 2.8%), and nephrotoxicity (n=1, 0.5% vs n=0). No death was considered related to ARIKAYCE or placebo. The treatment discontinuation rate was 18.3% in the ARIKAYCE arm and 11.8% in the comparator arm. Study completion rates were 90.6% in the ARIKAYCE arm and 93.4% in the comparator arm.