Denali Therapeutics' drug for Hunter syndrome (MPS II) has not been approved by the FDA, despite the title of the article stating the approval; the current status is an extension of the review.[1][6] The only approved drug for Hunter syndrome is Takeda's Elaprase, which is administered intravenously and replaces the enzyme that breaks down glycosaminoglycans, but it cannot cross the blood-brain barrier and does not treat neurological symptoms.[1] Tividenofusp alfa (DNL310) from Denali Therapeutics is an iduronate-2-sulfatase (IDS) enzyme coupled to a TransportVehicle™ platform designed for delivery to the brain and body to address behavioral, cognitive and physical symptoms.[3][6] The FDA has extended review of the Biologics License Application (BLA) for expedited approval from January 5, 2026 to April 5, 2026.[6] The drug has Fast Track, Breakthrough Therapy, Orphan Drug, and Rare Pediatric Disease designations from the FDA, as well as Priority Medicines from the EMA.[3][6][7] Hunter syndrome is a rare genetic lysosomal disorder caused by mutations in the IDS gene, leading to a deficiency of an enzyme to break down GAGs such as heparan sulfate and dermatan sulfate.[3][6] The FDA recently rejected REGENXBIO's RGX-121 gene therapy, putting the spotlight on Denali.[1] Denali is being prepared for possible approval and marketing.[3][6]