Cleveland Clinic’s first Phase 1 clinical trial in humans has shown that a single injection of CRISPR-Cas9 gene editing can produce a sustained reduction in LDL, the “bad” cholesterol, and triglyceride levels in people for whom medication has not provided sufficient results. The study involved 15 people who were followed for one year to determine whether the changes recorded within two months would persist.
Among participants who received the highest dose, LDL cholesterol was 52.5% below baseline after 12 months, while triglycerides had fallen by 47.8%. In that group, both measures declined by about 50% on average. No serious treatment-related adverse events were reported during the one-year trial.
The tested CTX310 is a one-time injection that delivers the CRISPR system to the liver and switches off the ANGPTL3 gene. The gene is involved in regulating fats circulating in the blood, and switching it off may reduce LDL cholesterol and triglycerides. Participants received doses ranging from 0.1 to 0.8 mg/kg, while corticosteroids and antihistamine medications were administered before the injection.
The results were presented at the 2026 annual meeting of the European Society of Cardiology and published simultaneously in the New England Journal of Medicine. Researchers plan to continue long-term safety monitoring of the participants for another 15 years, in line with FDA recommendations for gene-editing therapies. CTX310 remains an experimental treatment, and the results from this phase are based on data from just 15 participants.
The findings illustrate the different approach gene editing is attempting to offer: rather than repeatedly controlling blood fat levels with medication, the goal here is to intervene once and maintain the effect over a prolonged period. However, the results of this trial do not yet provide a basis for broad use, as the study involved only 15 people and CTX310 remains an experimental treatment.
The next important stage is long-term safety monitoring, particularly because researchers plan to follow the participants for another 15 years. The data collected during this period will provide a more complete picture not only of how long the effects last, but also of the long-term safety of an intervention such as gene editing.
