A patient in Intellia Therapeutics’ in vivo CRISPR trial for transthyretin (ATTR) amyloidosis died after hospitalization for liver injury, prompting intensified safety reviews and an FDA clinical-hold inquiry. Intellia and partner Regeneron confirmed the death and said they have increased post-dosing lab monitoring at MAGNITUDE and MAGNITUDE-2 sites while awaiting a formal FDA hold letter. The company reported the event followed Grade 4 transaminase elevations and elevated bilirubin in a small subset of dosed patients; Intellia said such severe elevations have been rare across the enrolled cohort. Intellia stressed its continued belief in nex-z’s therapeutic potential but is consulting outside experts and regulators on additional mitigation measures. Regulatory and investor attention will center on whether the liver injury represents an idiosyncratic severe adverse event or a dose-related safety signal for in vivo CRISPR therapies. That distinction will influence monitoring requirements, trial design changes, and the broader oversight of gene‑editing assets administered systemically.