Insmed Shares Rise as FDA Grants Priority Review for Arikayce Expansion

Shares of Insmed Incorporated (NASDAQ: INSM) rose approximately 2% in premarket trading after the U.S. Food and Drug Administration (FDA) granted Priority Review to the company's supplemental New Drug Application (sNDA) for its treatment Arikayce.

FDA Sets Review Timeline

The FDA accepted the sNDA for Arikayce (amikacin liposome inhalation suspension) for the treatment of *Mycobacterium avium* complex (MAC) lung disease as part of a combination antibacterial drug regimen. The agency has set a target action date of January 28, 2027, under the Prescription Drug User Fee Act (PDUFA).

The FDA grants Priority Review to drug applications that, if approved, would represent a significant improvement in the safety or effectiveness of treating a serious condition. This designation shortens the standard review timeline.

Path to Full Approval

Arikayce currently holds an accelerated approval from the FDA, granted in 2018, for treating refractory MAC lung disease in a limited population. This sNDA seeks full approval, which could make the drug available to patients earlier in their disease course and would also fulfill a post-marketing requirement from the agency.

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The drug was the first product approved under the FDA's Limited Population Pathway for Antibacterial and Antifungal Drugs, a program designed to advance the development of treatments for serious or life-threatening infections affecting a limited number of patients.

Supporting Clinical Data

The application is supported by positive results from the Phase 3b ENCORE study. Key findings from the trial include:

• The study enrolled 425 patients across 177 sites globally.
• It met its primary endpoint and key secondary endpoints related to culture conversion.
• The Arikayce combination therapy demonstrated statistically significant improvements in respiratory symptoms and culture conversion compared to multidrug therapy alone.

The safety profile observed in the study was consistent with the known risks of Arikayce, with no new safety signals identified. Insmed also noted it plans to discuss the ENCORE data with regulators in Japan in the fourth quarter of 2026 to support a potential label expansion in that market.