Intellia disclosed the death of an elderly participant in its Phase III MAGNITUDE program for nexiguran ziclumeran (nex‑z) and subsequently paused dosing and screening across two trials. The patient developed severe liver dysfunction roughly 24 days after dosing, prompting Intellia to report the event and the FDA to place the program on clinical hold for further review. Intellia said the case involves complicating comorbidities and that it is working with investigators and external experts to investigate liver‑related events and design risk‑mitigation measures. The company is collaborating with Regeneron on this in‑vivo CRISPR therapy that targets the TTR gene for ATTR cardiomyopathy. Investors reacted sharply, driving steep share declines in Intellia and related partners, while regulators signaled increased scrutiny of in‑vivo gene editing safety signals. The company expects formal FDA correspondence and indicated it will provide updates as analyses conclude.