Intellia Therapeutics paused dosing and screening in two Phase III programs for its in vivo CRISPR candidate nexiguran ziclumeran (nex‑z) after a patient experienced severe liver injury; the FDA subsequently placed a clinical hold on the INDs for both MAGNITUDE trials. The hospitalized patient showed AST/ALT and bilirubin elevations meeting Hy’s law criteria, prompting regulator intervention and an internal safety review by Intellia. MAGNITUDE and MAGNITUDE‑2 together had dosed hundreds of patients across ATTR‑CM programs, and Intellia disclosed the pauses in regulatory filings. The hold stalls a high‑profile in vivo CRISPR effort developed in partnership with Regeneron and will force the company and regulators to evaluate causality, patient selection, and monitoring protocols before dosing can resume.