Intellia Therapeutics disclosed the death of an elderly patient in its Phase III MAGNITUDE trial of nexiguran ziclumeran (nex‑z), an in vivo CRISPR base‑editing therapy for transthyretin amyloidosis with cardiomyopathy (ATTR‑CM). The company paused dosing and screening across the pivotal trials and the FDA placed the studies on clinical hold while it evaluates reported liver dysfunction events. Intellia said the patient experienced Grade 4 transaminase elevations and hyperbilirubinemia about three weeks after dosing; the company and independent investigators are assessing comorbidities and potential mechanistic drivers. Intellia said it is collecting added labs at early post‑dose time points and is developing a risk‑mitigation plan, while the broader gene‑editing field watches for regulatory precedent and safety implications for LNP‑delivered in vivo editing.