Intellia voluntarily paused dosing and screening in its Phase III MAGNITUDE program and a companion Phase III trial after a patient experienced Grade‑4 liver transaminase elevations and hyperbilirubinemia meeting Hy’s law criteria. The FDA subsequently placed the MAGNITUDE and MAGNITUDE‑2 INDs on clinical hold. The affected program, nexiguran ziclumeran (nex‑z), is an in‑vivo CRISPR candidate developed with Regeneron to inactivate the TTR gene in ATTR‑CM. Intellia reported more than 450 patients had been dosed across trials; the agency’s hold will require safety investigations and data review before dosing can resume. The pause and hold underscore elevated regulatory scrutiny for systemic in‑vivo gene‑editing platforms after serious hepatic adverse events, and they will directly affect timelines, enrolment and capital planning for Intellia and partners.