Intellia Therapeutics Inc. announced positive follow-up data from its ongoing Phase 1 clinical trial of nexiguran ziclumeran (nex-z), an investigational therapy for patients with transthyretin $(ATTR)$ amyloidosis with cardiomyopathy. The results were presented at the American Heart Association (AHA) Scientific Sessions 2025 in New Orleans. According to the company, a single dose of nex-z resulted in a rapid, deep, and durable reduction in serum transthyretin (TTR) levels, with stability or improvement in multiple markers of cardiomyopathy observed at 24 months. Nex-z was generally well tolerated, with the most common treatment-related adverse events being infusion-related reactions and transaminase elevations, none exceeding Grade 2. Deaths reported during the study were attributed to the progression of underlying cardiovascular disease. Longer-term safety data were consistent with previous reports from the Phase 1 trial.