In the first human phase 1 clinical trial of its kind at Cleveland Clinic, a single infusion of the CRISPR-Cas9 gene-editing therapy CTX310 led to sustained reductions in LDL (“bad”) cholesterol and triglycerides. The participants had dyslipidemia and had not responded well to drug therapy.

The study followed 15 patients for 12 months to evaluate changes in cholesterol and triglyceride levels. After one year, participants who received the highest dose of CTX310 had an average 52.5% reduction in LDL cholesterol and a 47.8% reduction in triglycerides from baseline.

No serious treatment-related adverse events were reported during the one-year follow-up.

Cholesterol reductions lasted for 1 year

The findings were presented at the 2026 European Society of Cardiology Annual Meeting and published simultaneously in the New England Journal of Medicine. The results build on previously reported findings from the trial.

“The durability of lipid-lowering effects was impressive, based on initial data published in November 2025,” said Cleveland Clinic cardiologist Luke Ruffin, M.D., the study’s lead author. “We are encouraged that no serious safety events related to CTX310 occurred during the study or during the year following treatment. We look forward to continuing to investigate this therapy in a larger number of patients.”

CRISPR-Cas9 is a gene-editing technology designed to make targeted changes to specific parts of a person’s DNA. Researchers are studying whether it can help treat serious diseases by modifying genes involved in disease processes.

How CTX310 targets LDL cholesterol and triglycerides

CTX310 is an experimental, one-time infusion designed to deliver the CRISPR editing system to the liver. There, it switches off a gene called ANGPTL3.

ANGPTL3 helps regulate the amount of fat circulating in the blood. Disabling the gene can reduce LDL cholesterol and triglycerides, which are associated with cardiovascular disease.

During the study, patients received CTX310 at doses ranging from 0.1 to 0.8 mg/kg. Before the infusion, they were treated with corticosteroids and antihistamines.

Researchers monitored participants for treatment-related safety issues and measured changes in ANGPTL3, LDL cholesterol and triglyceride levels.

At the highest dose, CTX310 lowered both LDL cholesterol and triglycerides by an average of approximately 50% 12 months after treatment.

Long-term safety monitoring will continue

Although the early results are promising, CTX310 remains experimental, and the phase 1 study included only 15 participants.

Researchers plan to continue long-term safety follow-up for an additional 15 years, in line with FDA recommendations for gene-editing therapies.

This research was funded by CRISPR Therapeutics AG, Zug, Switzerland.

Dr. Ruffin’s institution has received research funding from CRISPR Therapeutics.