The FDA placed a clinical hold on Intellia’s two Phase 3 studies of nexiguran ziclumeran (nex‑z), a CRISPR‑based therapy for transthyretin amyloidosis, following liver safety signals. The agency’s pause covers pivotal trials designed to inactivate the disease‑causing gene using in vivo gene editing. Intellia and investigators will need to provide additional safety data and mitigation plans before dosing can resume, underscoring heightened regulatory scrutiny of systemic gene‑editing programs and the need for clarified safety pathways for in vivo CRISPR therapeutics.