A new experimental treatment for hepatitis B has demonstrated the ability to allow some patients to discontinue therapy while maintaining viral suppression, marking what researchers are calling a functional cure—a significant development in treating a disease that kills approximately 1.1 million people annually worldwide.
The drug, bepirovirsen (nicknamed "bepi"), developed jointly by GSK and Ionis Pharmaceuticals, showed in two international clinical trials that roughly 1 in 5 patients achieved sustained viral suppression low enough for their immune systems to control the infection without ongoing treatment. The medication is currently under fast-track FDA review, with a regulatory decision expected in October, while regulators in Japan, China, and Europe are also evaluating the treatment.
Breaking Through Treatment Limitations
Chronic hepatitis B represents a persistent public health challenge, with approximately 1.7 million infected individuals in the U.S. and more than 250 million worldwide. Current standard treatments—typically daily pills—reduce viral levels and prevent liver damage but cannot cure the infection because hepatitis B possesses an unusual ability to hide dormant in the body, capable of rebounding once therapy ceases.
Dr. Seng Gee Lim of the National University Health System of Singapore, who led the GSK-funded research, stated: "We have not had a treatment which has come to this level of cure." The findings were presented Thursday at a scientific meeting in Barcelona, Spain, and published the same day in the New England Journal of Medicine.
The mechanism of action represents a meaningful departure from existing therapies. According to GSK vice president Melanie Paff, bepirovirsen works by binding to hepatitis B's genetic components, suppressing viral replication while simultaneously targeting the virus's "S" or surface protein and stimulating immune system response—a multi-pronged approach designed to achieve what traditional antivirals cannot.
Clinical Trial Results and Patient Selection
The trials enrolled 1,838 patients who received weekly injections of either bepirovirsen or a placebo for six months alongside their regular antiviral medications. Patients whose virus became undetectable for six months following the injection phase were permitted to discontinue all treatment. Approximately 20 percent of bepirovirsen recipients maintained undetectable viral levels for an additional six months after stopping all therapy—achieving the functional cure—compared to zero percent in the placebo group.
Researchers identified a potential predictor of treatment success: patients beginning the study with lower baseline levels of the S protein demonstrated slightly higher likelihood of achieving functional cure. Dr. Lim indicated ongoing research to understand why only a subset of patients respond to the treatment.
Regarding durability, GSK has monitored a small cohort from earlier-stage studies, with most patients remaining stable up to three years post-treatment, according to Paff. The safety profile appeared favorable, with side effects limited to mild injection-site reactions and temporary elevation in liver enzymes.
Important Research Gaps
Dr. Anna Lok, a hepatitis expert at the University of Michigan who was not involved in the research, acknowledged the findings "represent a major step," but cautioned that additional study is necessary to determine the longevity of the remission-like state. Notably, the trials excluded patients with cirrhosis, elevated S protein levels, and other complicating factors—populations that represent a significant portion of the hepatitis B-infected population requiring treatment.
Hepatitis B, spread through contact with blood or bodily fluids including childbirth, can progress to chronic infection in some individuals, gradually damaging the liver and potentially causing cancer or liver failure. While an effective vaccine exists for prevention, treatment options for those already infected have remained limited by the virus's capacity to persist despite therapy.
Why This Matters:
From a public health and market perspective, bepirovirsen represents a potential breakthrough in addressing a disease burden that has resisted curative solutions for decades. The functional cure approach could reduce the lifetime treatment burden and associated healthcare costs for millions of patients globally. However, the modest 20 percent efficacy rate and exclusion of cirrhotic patients from trials indicate this is not a universal solution. The October FDA decision will determine whether this therapy becomes available in the U.S. market, potentially creating competitive pressure on existing hepatitis B treatment providers while establishing new treatment paradigms. The durability data—currently limited to three-year follow-up—remains incomplete, underscoring the importance of continued monitoring before widespread adoption. For healthcare systems and patients, this development offers hope for treatment simplification, though cost considerations and patient selection criteria will likely shape real-world implementation.