The U.S. Food and Drug Administration has placed clinical holds on Intellia’s Phase 3 studies of nexiguran ziclumeran (nex‑z), a CRISPR‑based gene editing therapy for transthyretin amyloidosis, after reports of liver complications. The agency suspended dosing while it investigates safety signals tied to hepatotoxicity. Intellia’s programs employed in vivo CRISPR to inactivate the pathogenic TTR gene; the hold pauses two pivotal trials and will require additional safety data before lifting. The development interrupts late‑stage development timelines and raises questions about risk management for systemic CRISPR therapies. Observers say the move could prompt sponsors to refine liver‑toxicity monitoring and preclinical safety studies for nuclease‑based therapies. Companies developing systemic gene editors will likely reassess dose, delivery, and biomarker strategies in light of the FDA’s action.