An experimental gene therapy for high cholesterol is showing promise in clinical trials and inching closer to approval.

The treatment, called VERVE-102, is being tested in people with familial hypercholesterolemia (FH), an inherited condition that raises the levels of low-density lipoprotein (LDL) cholesterol — the “bad” kind — in the blood. It’s also being tested in people with premature coronary artery disease (CAD), in which the arteries narrow and can’t deliver enough oxygenated blood to heart muscle. The age at which CAD is considered “premature” varies, but it generally occurs before age 65 in women and age 55 in men.

Both groups “require deep and durable reductions” of LDL in the blood, Verve Therapeutics, the treatment’s maker, noted in an April statement. In an ongoing clinical trial, the company tested the treatment in 14 people with FH and/or premature CAD, and found that a single dose of the therapy led to a 53% reduction in LDL, on average.

These early data are drawn from three groups of people who received different doses of the treatment. The four participants given the highest dose saw the largest benefit: a 69% reduction in LDL, at maximum.

Across the groups, “VERVE-102 was well-tolerated, with no treatment-related serious adverse events (SAEs) and no clinically significant laboratory abnormalities observed,” Verve’s statement noted.

VERVE-102 uses a modified version of CRISPR, the famous gene-editing system. The CRISPR systems developed originally introduce a “break” in both strands of a DNA molecule, and then, the cell’s built-in repair system swoops in to repair the break. However, this comes with the risk of adding unwanted mutations to the DNA.