The FDA extended its review of Denali Therapeutics’ biologics license application for tividenofusp (tivi), an enzyme replacement therapy for Hunter syndrome, moving the PDUFA date three months to April 5, 2026. Denali said the agency classified updated clinical pharmacology information as a major amendment, triggering the extension even though the company maintains the submission does not alter benefit‑risk or efficacy conclusions. Denali emphasized the amendment was procedural and tied to corrected molecular weight information that the FDA requested, but analysts called the extension a near‑term commercial and timing risk for a rare‑disease approval. Management said it remains prepared for potential approval and commercial launch planning. The delay adds to a broader pattern of procedural extensions and regulatory uncertainty impacting rare‑disease filings this year, underscoring the importance of late‑stage manufacturing and analytical clarity in late BLA reviews.