An experimental gene-editing treatment, VERVE-101, has successfully reduced bad cholesterol levels in human subjects by up to 55% in a clinical trial. The treatment uses base editing to turn off the PCSK9 gene, which regulates low-density lipoprotein (LDL). However, safety concerns have been raised after one participant died and another suffered a non-fatal heart attack post-treatment. Biotech firm Verve Therapeutics plans to launch a phase 2 trial in 2025.