The FDA pushed back its review decision on Denali Therapeutics’ candidate for Hunter syndrome by three months after the company submitted updated clinical pharmacology information, which the agency classified as a major amendment. Denali said the submission did not change efficacy or safety data but required an extension to the PDUFA action date. Denali framed the amendment as administrative and continued to prepare for a potential launch pending approval. Analysts characterized the delay as procedural but noted such extensions can affect commercial planning and investor expectations when they occur late in a review cycle. Regulatory note: Agency-requested major amendments trigger automatic clock extensions; companies often engage closely with the FDA to resolve technical queries that do not alter benefit–risk assessments but do change the review schedule.