A new epigenetic editing therapy has shown promise in blocking the activity of the hepatitis B virus (HBV) during experiments on human cells and animal models. The treatment uses a modified version of the Cas9 protein, commonly used in the CRISPR gene-editing system, but without its usual DNA-cutting function. Instead, it targets the HBV genome by marking it with chemical tags that reduce its activity, without directly altering the DNA sequence. This approach aims to disable the viral DNA and prevent the virus from replicating. The therapy, named CRMA-1001, is delivered through injectable lipid nanoparticles and has demonstrated effectiveness in preclinical studies. Chronic hepatitis B is a serious global health issue, affecting nearly 250 million people and contributing to over one million deaths annually, mainly due to liver disease and liver cancer. The virus can persist in the body for years, partly because it maintains a special form of DNA called covalently closed circular DNA (cccDNA) in liver cells. This genetic structure acts as a blueprint for the virus to replicate quickly if a patient stops their treatment. Current antiviral therapies rarely lead to a complete cure, and only a small percentage of patients can stop treatment without facing a risk of severe relapse. Researchers from nChroma Bio in Boston and institutions in Milan have tested CRMA-1001 in human liver cells and mice. The treatment effectively targeted HBV DNA, reducing its transcription and the production of viral proteins and particles. In mouse models, a single injection significantly reduced viral DNA and HBV proteins, with some animals showing undetectable levels of the virus six months later. The results were described as "very impressive" by experts, who see this as a potential breakthrough in the fight against the hepatitis B pandemic. While the therapy appears safe in animal studies, its effectiveness in humans is still unknown. Researchers have begun clinical trials in Hong Kong and New Zealand, with the first participant receiving the treatment in January 2026. The trials will assess the treatment’s safety and effectiveness in humans and may lead to further studies in the UK and France. Although the approach avoids the risks of traditional gene editing, more research is needed to ensure that it does not cause unintended effects, such as unwanted changes in gene regulation. The ultimate goal is to achieve a functional cure, where the virus is suppressed to undetectable levels and does not cause disease.