Intellia Therapeutics paused enrollment and dosing in two Phase III trials of its in vivo CRISPR candidate (nex‑z) after a study participant was hospitalized with severe liver injury. The company halted screening and dosing while it investigates the safety signal and implements an updated monitoring protocol. Intellia characterized the event as a serious adverse reaction under review with investigators and regulators. The pause sent Intellia shares sharply lower and renewed scrutiny of systemic, in‑body gene editing safety, particularly for liver‑directed editing modalities. Biotech partners and investors are watching any regulatory guidance that emerges; the episode underscores the operational and reputational risk CRISPR pioneers face as they move into larger, later‑stage trials.