Intellia Therapeutics paused enrollment and dosing in two phase III trials of its CRISPR candidate nex‑z (nexiguran ziclumeran) after a study volunteer was hospitalized with severe liver toxicity. The company said it has suspended screening and dosing while it assesses the event and implements enhanced safety monitoring procedures. Intellia’s move raises immediate regulatory and commercial questions for in vivo CRISPR therapies, a modality that has faced liver safety concerns before. The company notified investigators and investors; shares plunged on the announcement. Intellia said it will work with regulators and independent reviewers to determine next steps and patient protections. CRISPR medicines that edit genes inside patients require robust hepatic safety oversight because many delivery routes and targets involve the liver—an organ that has shown vulnerability in prior gene‑editing programs.