Intellia Therapeutics paused enrollment and dosing in two late‑stage trials of its in vivo CRISPR program (nex‑z) after a trial volunteer was hospitalized with life‑threatening liver toxicity. The company said it is pausing operations while it investigates the event and implements a revised safety monitoring plan. Intellia’s leadership notified investors and temporarily suspended dosing pending root‑cause analysis and regulatory updates. The pause affects pivotal programs in transthyretin amyloidosis (ATTR) and represents a material safety setback for in‑vivo CRISPR approaches that edit the liver. Market reaction was immediate with steep share declines. The company and regulators will now evaluate causality, confounding factors and any protocol or manufacturing changes required before resuming enrollment. The episode underscores ongoing hepatic safety scrutiny for direct in‑patient gene‑editing medicines, and it could force sponsors to redesign monitoring, dosing or patient selection criteria across the field.