One CRISPR shot cut ‘bad’ cholesterol in half and it lasted a full year

A single intravenous infusion of an experimental CRISPR-Cas9 therapy cut LDL cholesterol by 52.5% in patients who received the highest dose, and the effect was still holding a full year after treatment. Cleveland Clinic cardiologist Luke Laffin led the 15-patient Phase 1 trial of the drug, called CTX310, developed by CRISPR Therapeutics and built to permanently switch off a single gene in the liver rather than lower cholesterol through a daily pill.

Triglycerides fell by 47.8% in the same top-dose group over the same 12 months, and researchers reported no serious side effects tied to the therapy during that stretch. The results, published in the New England Journal of Medicine and presented at the European Society of Cardiology’s 2026 congress, mark one of the first times a gene-editing drug aimed at heart disease risk has shown this kind of durability in people rather than only in animal models.

Switching off ANGPTL3 instead of blocking it with a pill

High LDL cholesterol is not a rare condition to be targeting this way: CDC data put the number of American adults with total cholesterol above 200 mg/dL at roughly 86 million, a population far larger than the 15 people who have so far received CTX310. CTX310 targets a gene called ANGPTL3, which normally produces a protein that interferes with the body’s ability to clear fats from the bloodstream. Existing cholesterol drugs work by blocking that protein’s activity or by boosting receptors elsewhere in the liver; CTX310 instead uses CRISPR-Cas9 editing to disable the gene itself inside liver cells, aiming for a change that does not require repeat dosing. In the trial’s highest-dose group, that editing translated into an average 79% drop in ANGPTL3 protein levels a year out, with some patients reaching as high as 89%, according to CRISPR Therapeutics’ own summary of the data presented at the cardiology congress.

The gap between switching off a gene and blocking a protein pharmacologically is the entire premise behind the trial. A statin or injectable antibody drug loses its effect within days or weeks of the last dose; a permanent edit to liver DNA, if it holds, keeps working without any further action from the patient.

Five dose levels, and one that outperformed the rest

Researchers tested CTX310 across five sequential dose cohorts, from 0.1 milligrams per kilogram up to 0.8 milligrams per kilogram, giving each of the 15 participants a single infusion after pretreatment with corticosteroids and antihistamines to reduce infusion reactions. Only the top dose group reached the full 52.5% LDL and 47.8% triglyceride reductions; CRISPR Therapeutics’ presentation at the congress showed the effect scaling with dose across the lower cohorts rather than appearing all at once.

Patients enrolled had lipid disorders that had not responded adequately to existing medications, meaning the comparison was not against untreated cholesterol but against levels that standard drugs had already failed to bring down. That detail matters for how the results get read: a therapy competing against pills that already work well for most patients faces a much higher bar than one aimed at people who have run out of other options.

One allergic reaction and a few infusion reactions, but no serious events

Safety data released alongside the efficacy numbers included one allergic reaction that resolved with supportive care, three Grade 2 infusion-related reactions, and one transient rise in liver enzymes after treatment. None of the 15 patients experienced a dose-limiting toxicity, a serious adverse event tied to the therapy, or a Grade 3 or higher liver enzyme change, according to Cleveland Clinic’s account of the trial.

“Building upon the initial data presented in November 2025, the durability of the lipid-lowering effect was impressive,” Laffin said, describing results that extended a smaller readout from months earlier into a full year of follow-up. “It is encouraging that there were no serious safety events related to CTX310 in the trial and in the year following treatment,” he added. Cleveland Clinic cardiologist Steven Nissen, quoted in the same presentation materials, called the result “a meaningful advance” for a one-time treatment.

Fifteen years of watching, under the FDA’s own rule for gene editing

A single year of clean safety data is not the end of the monitoring period. ScienceDaily’s account of the study notes that researchers plan to continue long-term safety follow-up for another 15 years, in line with FDA recommendations that apply to gene-editing therapies generally, not something specific to CTX310’s early results. That timeline reflects a standing regulatory concern with any treatment that permanently alters a patient’s DNA: effects that look clean at 12 months can still take years to fully surface, whether in liver function, immune response, or effects on other genes near the edited site.

CRISPR Therapeutics has not announced enrollment numbers or a start date for a larger trial, though the full write-up of the Phase 1 results frames the 15-patient data as the basis for expanding into a bigger patient population next. Whether CTX310 eventually reaches people with ordinary, medication-responsive high cholesterol, rather than only those who have exhausted other options, depends on data that a single year, however durable, cannot yet provide.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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