Intellia Therapeutics halted dosing and screening across its Phase III MAGNITUDE program and a second Phase III trial after a participant developed severe liver injury that met Hy’s law criteria. The company disclosed the voluntary pauses following hospitalization of an elderly patient with Grade 4 transaminase elevation and hyperbilirubinemia roughly three weeks after dosing. The FDA escalated the response by placing clinical holds on the Investigational New Drug (IND) applications for both trials, restricting further dosing while regulators and Intellia investigate causality and safety signals. MAGNITUDE tested nexiguran ziclumeran (nex‑z), an in vivo CRISPR therapy partnered with Regeneron aimed at inactivating the TTR gene for transthyretin amyloid cardiomyopathy. Intellia reported the event after more than 450 patients had been dosed across both programs; the patient remained stable at the time of reporting. The development forces a pause in a high‑visibility in vivo CRISPR program and will focus attention on hepatic safety for systemic gene‑editing approaches.