A drug called bepirovirsen has produced what researchers describe as a functional cure for chronic hepatitis B in approximately 20 percent of patients enrolled in a large international clinical trial, representing the most significant development in the treatment of a disease that kills more than one million people annually and has no existing cure.
The trial results, published in the New England Journal of Medicine, enrolled 1,834 adults with chronic hepatitis B who were not experiencing liver cirrhosis, drawing participants from 29 countries across Europe, the Asia-Pacific region, and the Americas. Participants received weekly injections of bepirovirsen or a placebo for 24 weeks, alongside their existing standard oral antiviral medication. The results measured at 72 weeks showed that none of the placebo recipients achieved a functional cure, while roughly one in five bepirovirsen recipients did.
What a functional cure means
The term functional cure refers to a state in which the virus becomes undetectable in the body without any continuing treatment. It is distinguished from complete eradication of all viral genetic material, which remains a more distant goal, but it is meaningfully different from the suppression that current therapies achieve. Under standard treatment, patients take antiviral medication indefinitely because stopping it allows the virus to rebound.
A functional cure eliminates the need for ongoing antiviral therapy, removing the associated risks of drug resistance, treatment nonadherence, and the long-term side effects that accumulate with prolonged use of existing hepatitis B medications. Those side effects can include kidney damage and bone loss, and in rare cases more severe reactions involving blood chemistry or liver function.
The implications for the approximately 240 million people worldwide living with chronic hepatitis B are significant. Current treatment converts an acute threat into a managed chronic condition requiring lifetime pharmaceutical management. A functional cure converts it into something that can be resolved.
Stronger results in certain patient groups
The overall functional cure rate of approximately 20 percent improved among patients who began the trial with lower levels of a protein associated with active hepatitis B infection. In that subgroup, cure rates reached between 25 and 28 percent, suggesting that the drug may be more effective when the viral burden at the start of treatment is lower.
An additional finding reinforced the drug’s potential. Around 24 percent of bepirovirsen recipients were able to discontinue their existing oral antiviral medication entirely by week 48 of the study, compared to none in the placebo group. Among patients who stopped that medication without achieving a full functional cure, none experienced a dangerous rebound of the virus, a result that addressed a significant safety concern about what happens when treatment is withdrawn.
How the drug works
Bepirovirsen targets the genetic components of the hepatitis B virus, directing the body’s mechanisms to recognize and destroy viral material rather than simply suppressing viral replication as existing drugs do. That mechanism of action is what distinguishes it from current standard of care and what makes the functional cure outcome possible in a way that other treatments have not achieved.
Hepatitis B remains one of the leading infectious disease killers globally, surpassing many more prominently discussed pathogens in annual mortality. The virus causes liver inflammation that can progress to cirrhosis and liver cancer over decades, making it a slow-moving but devastating public health problem. A treatment capable of resolving the infection rather than managing it indefinitely would represent a fundamental change in how the disease is addressed worldwide.
Further research will be needed to confirm these findings, optimize patient selection, and understand long-term durability before bepirovirsen can become a standard treatment option.
