MUNICH — For roughly one in five people who need to control their cholesterol, statins don’t work. Not because the drugs fail, but because the side effects are intolerable. Muscle pain that disrupts sleep, fatigue that makes ordinary work difficult, a biochemical intolerance that resolves only when the pills stop. Those patients cycle through combinations of expensive injectable antibodies and older compounds without a permanent answer.
At the European Society of Cardiology Congress here on Thursday, researchers presented data suggesting that a single injection might eventually settle that problem permanently.
The treatment is CTX310, an experimental in vivo CRISPR-Cas9 gene-editing therapy developed by CRISPR Therapeutics. A one-time intravenous infusion delivers lipid nanoparticles into the bloodstream; those particles carry the CRISPR editing machinery directly to liver cells, where they switch off a gene called angiopoietin-like protein 3, known as ANGPTL3. That gene governs how much fat the liver releases into circulation. Knock it out, and both LDL cholesterol and triglycerides fall. And keep falling.
In a Phase 1a trial involving 15 patients with lipid disorders resistant to standard medications, the highest dose of CTX310 produced a mean reduction in LDL cholesterol of 52.5% at one year of follow-up. Triglycerides fell by a mean of 47.8%. ANGPTL3 itself declined by 78.6%. No patient experienced a treatment-related serious adverse event. No patient showed a grade-3 or higher rise in liver enzymes, the hepatic safety signal the trial protocol was designed to capture.
The findings were presented simultaneously in the New England Journal of Medicine, in the study, making this the longest human durability dataset yet published for an in vivo gene-editing approach to cholesterol management.
“This is really unprecedented,” said Dr. Luke J. Laffin, lead study author and preventive cardiologist at the Cleveland Clinic. “If confirmed in larger trials, this one-and-done approach could transform care for people with lifelong lipid disorders and dramatically reduce cardiovascular risk.”
Dr. Stephen J. Nicholls, director of the Victorian Heart Institute at Monash University and a co-investigator on the trial, said that sustaining both LDL and triglyceride reductions for a full year from a single infusion, with no re-dosing, was an outcome the field had modeled in theory but not demonstrated in humans until now.
What the trial cannot show is the outcome that ultimately matters most in preventive cardiology: whether the LDL reduction prevents heart attacks and strokes. That requires thousands of patients and years of follow-up. Phase 1a trials are designed around safety and early efficacy signals, not cardiovascular endpoints. Fifteen patients over twelve months is enough to detect a serious adverse event pattern. It is not enough to say whether a 52.5% LDL reduction translates into proportionally fewer cardiac events for the patients who need it most.
The biological mechanism underpinning CTX310 is grounded in an observation from nature. ANGPTL3 was identified as a lipid regulator when researchers studying an extended family with unusually low cholesterol found they carried a natural loss-of-function variant in the gene, and showed no apparent adverse effects from the protein’s absence. That observation eventually produced evinacumab, a monoclonal antibody that blocks the ANGPTL3 protein and gained FDA clearance in 2021 for homozygous familial hypercholesterolaemia, a severe inherited cholesterol disorder. Beyond evinacumab, the cholesterol-lowering pipeline has expanded in 2026 to include a new oral cholesterol pill of a novel class. CTX310 takes the same ANGPTL3 target a step further: rather than blocking the protein after it is made, the therapy edits the gene itself, aiming to silence production permanently after a single treatment.
That distinction is clinical as much as scientific. Evinacumab requires monthly infusions in a hospital or clinic setting. CTX310, if the durability holds, requires none.
The safety picture through twelve months is reassuring, though the investigators are careful not to overread a 15-patient sample. Three participants in the original cohort experienced minor infusion-related reactions: transient back pain and nausea that resolved with standard supportive care. One participant with abnormally elevated liver enzymes at baseline experienced a temporary further elevation that normalized spontaneously. CRISPR Therapeutics reported that no new treatment-related safety events emerged at any dose level through the one-year mark, in its update.
Durability remains the field’s central open question. Gene expression changes triggered by one-time molecular interventions have been documented in research settings across a range of applications, but whether CRISPR-induced silencing of a liver gene holds at two years, five years, or across a lifetime has not been tested in humans. The 12-month mark is the longest window the field has looked through. What lies beyond it is not yet visible.
CRISPR Therapeutics is advancing CTX310 into a Phase 1b clinical trial, with enrollment ongoing in the United States and internationally. The company expects to report additional program data before the end of 2026. Phase 2 studies, expected to evaluate efficacy in a broader, more diverse patient population and begin to answer the cardiovascular outcomes question in earnest, remain in planning.
The question cardiologists cannot yet answer is whether a 53% LDL reduction from a single injection produces a 53% reduction in cardiovascular events. It will take years of additional study to resolve. The data presented in Munich, for now, provide enough to ask it in earnest.
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