Intellia Therapeutics halted enrollment and dosing in two clinical trials of its in vivo CRISPR candidate, nex‑z, after a patient was hospitalized with liver toxicity. The company notified investors and paused activity to investigate safety signals tied to editing at the intended genomic site. A Biocentury clinical report expands the concern, documenting on‑target toxicity as a growing issue in gene‑editing programs and placing regulatory scrutiny on CRISPR in vivo approaches. The episode underscores the narrow therapeutic window for systemic gene editors and will likely slow regulatory timelines and industry risk appetite for first‑in‑human, whole‑organ editing trials. Clinicians and investors will watch Intellia’s safety investigations and any root‑cause analyses; regulators may demand additional preclinical work or modified dosing/monitoring plans. For readers: in vivo CRISPR delivers gene edits directly inside patients’ tissues, which increases potential systemic exposure and on‑target off‑tissue risk compared with ex vivo approaches.