One CRISPR infusion kept LDL cholesterol 53% lower a full year later

One intravenous infusion, given once, was still holding LDL cholesterol 53% lower a full year later. That is the result of CTX310, a CRISPR-Cas9 treatment that permanently switches off a single gene in the liver, measured in the highest-dose group of a 15-person trial. The ambition behind it is a heart treatment given once, not taken every day for life.

The same patients saw triglycerides, the other blood fat that clogs arteries, fall by an average of 48%. The protein the edit targets, ANGPTL3, dropped by 79% on average and by as much as 89% in one participant. The best individual responses were larger still: LDL cholesterol down 84% and triglycerides down 78%.

What makes the number matter is where it comes from. Most of these volunteers were already taking statins or ezetimibe, and 40% were on PCSK9 inhibitors, the strongest cholesterol drugs in routine use. Their levels were still too high. The CRISPR edit worked on top of that treatment, in people for whom existing medicine had run out of room.

The trial was built to test safety, not to prove a cure. Nobody in it had a treatment-related serious side effect over the year, according to the investigators at Cleveland Clinic who led it and the company that makes the therapy, CRISPR Therapeutics. It also leaves hard questions open.

How a single infusion edits a liver gene

CTX310 is not a drug in the usual sense. It is a set of instructions packed into lipid nanoparticles, tiny fat bubbles that the liver absorbs from the bloodstream. Inside them travel the messenger RNA for the Cas9 enzyme and a guide RNA that points it at the ANGPTL3 gene. Once inside liver cells, Cas9 cuts the gene and the cell’s own repair machinery leaves it broken. The cells stop making the protein, and because the change is written into their DNA, they keep not making it.

ANGPTL3 acts as a brake on the enzymes that clear fat from the blood. Remove the brake and triglycerides and LDL cholesterol are cleared faster. That is why one edit moves both numbers at once, something a statin does not do to the same degree.

The trial escalated the dose step by step, from 0.1 to 0.8 milligrams per kilogram of lean body weight, across 15 adults. They had inherited or mixed lipid disorders: homozygous and heterozygous familial hypercholesterolemia, severe hypertriglyceridemia, or both high LDL and high triglycerides. The primary goal was safety. Changes in ANGPTL3, triglycerides and LDL were secondary measures, and every participant has now been followed for at least a year.

“For patients at high cardiovascular risk, the biggest challenge is often not starting therapy but staying on it,” said Luke Laffin, the trial’s principal investigator and medical director of the Cleveland Clinic Coordinating Center for Clinical Research. “A single infusion producing durable reductions at one year is an encouraging signal that a one-time approach could help close that adherence gap.”

Why nature already ran this experiment

The target was not picked at random. Some people are born with a broken copy of ANGPTL3, and they have been studied for years. A large genetic analysis in the New England Journal of Medicine found that carriers of these loss-of-function variants had lower triglycerides and lower LDL cholesterol, and about 41% lower odds of coronary artery disease than people without them. People with natural mutations that fully switch the gene off live with lifelong low cholesterol and triglycerides and no apparent harm, according to the American Heart Association.

CTX310 tries to copy that lucky genetics in adults whose own genes point the other way. A drug that blocks the same protein already exists: evinacumab, an antibody approved for homozygous familial hypercholesterolemia, which patients receive as an infusion every four weeks. The CRISPR version aims to reach a similar effect once, instead of monthly for life.

For scale, a high-intensity statin is expected to cut LDL by 50% or more, and PCSK9 antibodies add a further large drop on top. The 53% reduction here came in patients who were largely already on those drugs, which is why cardiologists pay attention to it.

What one year of data doesn’t settle

Fifteen people is a very small study. It was open-label, meaning everyone knew they had received the treatment, and it had no placebo group. Only a subset of the 15 received the highest dose, so the headline averages rest on a handful of patients. The first report noted that participants were predominantly male and came from a narrow set of countries, so the results may not transfer to women or other populations.

The edit cannot be undone. A pill can be stopped if something goes wrong; a broken gene in the liver stays broken. That is the whole point of the approach and also its central risk, which is why US regulators recommend 15 years of follow-up after gene editing. “Safety will always be a major question in early-phase studies like this one,” Kiran Musunuru, a gene-editing cardiologist at Penn Medicine, told TCTMD when the first results came out.

Some safety signals already appeared early on. One participant had an allergic reaction that resolved the next day. Three had grade 2 infusion reactions. One, who already had raised liver enzymes, saw a brief further rise that returned to normal. A man in his fifties with familial hypercholesterolemia and a long history of heart procedures died suddenly 179 days after receiving the lowest dose; investigators did not attribute the death to the therapy. No new treatment-related events appeared in the extended follow-up.

There are metabolic trade-offs too. In the first readout, HDL cholesterol, the kind usually called good, fell by about 24% at the highest dose, a known effect of shutting down ANGPTL3. And lower blood fats are a proxy. The trial did not measure heart attacks or strokes, the outcomes that ultimately matter, and no study of this size could.

Common questions about the CRISPR cholesterol treatment

Is there a one-time treatment for high cholesterol?

Not an approved one. CTX310 is an experimental CRISPR-Cas9 therapy given as a single infusion, and in its first trial it kept LDL cholesterol 53% lower after one year at the highest dose. It is still in early clinical testing.

Is CRISPR gene editing for cholesterol permanent?

It is designed to be. The edit disables the ANGPTL3 gene in liver cells, and that change cannot be reversed. How long the effect lasts over decades is still unknown, which is why patients will be monitored for 15 years.

Does CTX310 replace statins?

Not yet. Most trial participants kept taking statins, ezetimibe or PCSK9 inhibitors, and the edit lowered their levels further on top of those drugs. Whether it could one day replace daily treatment has not been tested.

What does the ANGPTL3 gene do?

It makes a protein that slows the enzymes clearing triglycerides and cholesterol from the blood. People born with non-working copies have naturally low blood fats and a lower risk of coronary artery disease.

What comes next

The one-year results were published in the New England Journal of Medicine and presented at the European Society of Cardiology Congress on 28 August 2026, and Cleveland Clinic publicized them on 27 September. They extend the first results from the same trial, reported at the American Heart Association’s Scientific Sessions in November 2025, when LDL had fallen by nearly 50% and triglycerides by about 55% over the first weeks.

CRISPR Therapeutics has moved into a Phase 1b trial using a fixed dose equivalent to the 0.8 mg/kg that worked best, with sites in the United States and elsewhere. The company says it will report data from the trial’s severe hypertriglyceridemia group in the second half of 2026. The larger question, whether a single edit can prevent heart attacks over a lifetime, will take trials of thousands of people and many years to answer.

Reference: Laffin et al., “Durability of CRISPR-Cas9 Gene Editing Targeting ANGPTL3 with CTX310,” New England Journal of Medicine, 2026. DOI: 10.1056/NEJMc2609825

Tags: medicine, Cleveland Clinic, CRISPR, CRISPR Therapeutics, CTX310, gene editing