Intellia disclosed the death of an elderly participant in its Phase III MAGNITUDE trial of nexiguran ziclumeran for transthyretin amyloidosis with cardiomyopathy, citing Grade 4 liver transaminases and elevated bilirubin following dosing. The company voluntarily paused dosing and screening in MAGNITUDE and the smaller MAGNITUDE-2 study. The FDA subsequently placed a clinical hold on the Investigational New Drug (IND) applications for both trials. Intellia identified the patient as an early-80s man with high BMI and reported the adverse hepatic events about 24 days post-dose. The episode sharpens regulatory and safety scrutiny around in vivo CRISPR therapeutics and could slow enrollment timelines and development milestones while Intellia and regulators probe causality, risk factors and monitoring strategies.