Intellia Therapeutics paused enrollment and dosing in two Phase 3 trials of its in vivo CRISPR candidate after a study volunteer was hospitalized with severe liver toxicity. The company said it is evaluating the event and instituting a revised safety monitoring plan before resuming dosing. Intellia’s move follows growing scrutiny of liver safety in systemically delivered genome-editing programs. The pause affects pivotal studies for transthyretin amyloidosis, a field where alternative therapies exist, raising strategic and regulatory questions for Intellia’s near-term outlook. Investors reacted sharply to the news, reflecting the binary risk profile of one‑time gene-editing medicines where safety signals can halt development and materially affect company viability.