A breakthrough experimental drug is offering some hepatitis B patients a path to stop lifelong treatment — a development that researchers are hailing as a potential functional cure for a virus that kills approximately 1.1 million people worldwide each year.
The drug, bepirovirsen (nicknamed "bepi"), was tested in two international studies where about 1 in 5 patients achieved sustained viral suppression without ongoing medication. For patients who have endured decades of daily pills with variable access and adherence challenges, particularly in resource-limited settings, the findings represent a significant shift in how this chronic infection might be managed.
A Disease of Global Inequality
Hepatitis B remains a stark marker of global health disparity. While a highly effective vaccine can prevent the infection, approximately 250 million people worldwide live with chronic hepatitis B — a condition that gradually damages the liver and can lead to cancer or complete liver failure. In the United States alone, 1.7 million people carry the chronic infection. The burden falls disproportionately on populations with limited access to preventive vaccines and consistent medical care.
Current standard treatments, which include daily pills, can suppress the virus and prevent liver damage. However, they require lifelong adherence and continuous access — a burden that has proven unsustainable for many patients, particularly in lower-income countries. "Improvements to today's lifelong therapy, which can be hard to stick with or to access in some countries, have been sought for decades," according to the research presented this week.
How the Drug Works and What the Data Shows
Bepirovirsen, developed by GSK and Ionis Pharmaceuticals, operates through a novel mechanism. The drug binds to the virus's genetic components, suppressing viral replication and a key protein known as the "S" or surface protein, while simultaneously stimulating the immune system to maintain control of the infection.
In the clinical trials, 1,838 patients received either weekly bepi injections or dummy shots for six months, in addition to their regular antiviral pills. Those whose virus became undetectable for six months could then discontinue all treatment. Remarkably, about 20% of bepi recipients maintained undetectable viral levels for an additional six months after stopping all medication — a functional cure that no patients in the control group achieved.
Dr. Seng Gee Lim of the National University Health System of Singapore, who led the GSK-funded studies, stated: "We have not had a treatment which has come to this level of cure." The findings were presented at a scientific meeting in Barcelona, Spain on Thursday and published the same day in the New England Journal of Medicine.
Remaining Questions and Regulatory Path
While the results are promising, significant questions remain about durability and who will benefit most. Patients who started the study with lower levels of the S protein were slightly more likely to achieve a functional cure, though researchers are still investigating why only some patients respond to the treatment.
Long-term follow-up data is limited but encouraging. GSK has tracked a small number of patients from earlier-stage studies and found most still faring well up to three years later. Side effects reported were mild, including injection-site redness or pain and temporary rises in liver enzymes.
Dr. Anna Lok, a hepatitis expert at the University of Michigan who was not involved in the research, wrote in the New England Journal of Medicine that the new findings "represent a major step," but cautioned that more study is needed to determine how long the remission-like state lasts.
The drug is under fast-track review by the U.S. Food and Drug Administration, with a decision expected in October. Regulators in Japan, China, and Europe are also considering the treatment.
One significant limitation: the trials did not include patients with cirrhosis, high S protein levels, or other complicating factors — populations that often bear the heaviest disease burden and would benefit most from new treatment options.
Why This Matters:
For the estimated 250 million people living with chronic hepatitis B globally, a functional cure — even for a subset of patients — could transform disease management and quality of life. The ability to discontinue daily medication represents not merely a medical convenience but a potential equity issue: patients in under-resourced healthcare systems often struggle with medication access and adherence, making treatment-free remission particularly valuable. However, the drug's effectiveness appears limited to specific patient populations, raising questions about who will have access and whether pharmaceutical pricing will determine whether this breakthrough benefits the global poor or primarily wealthy patients in high-income countries. The regulatory decisions expected later this year will shape whether this innovation reaches the millions who need it most.