An experimental drug for hepatitis B has shown encouraging results in clinical trials, with a subset of patients achieving sustained viral suppression after discontinuation of treatment, suggesting potential progress toward a functional cure. The findings center on bepirovirsen, an investigational drug developed by GSK in collaboration with Ionis Pharmaceuticals.
Key Trial Results
According to researchers, bepirovirsen enabled about one in five patients in clinical trials to maintain undetectable viral levels even after stopping all therapy. In these patients, the immune system was reportedly able to keep the infection under control without further medication.
The lead investigator, Dr Seng Gee Lim, described the outcome as a significant milestone in the treatment of chronic hepatitis B, noting that such durable suppression had not previously been achieved in earlier therapeutic approaches. He added that the results of the study, which were published in the New England Journal of Medicine, mark an important step forward in the field.
How Bepirovirsen Works
Bepirovirsen works by targeting the genetic material of the hepatitis B virus. Researchers explained that it binds to viral components to suppress replication and reduce production of the virus's surface (S) protein, while also helping to stimulate the body's immune response.
Trial Design and Participants
The international trials enrolled 1,838 patients, who were randomly assigned to receive either weekly injections of bepirovirsen or a placebo over six months, alongside their standard hepatitis B medications. Researchers said patients whose virus remained undetectable for six months after stopping injections were subsequently allowed to discontinue their routine oral treatments.
According to the study findings, around 20 percent of those treated with bepirovirsen maintained undetectable viral levels for a further six months after all therapy was stopped, meeting the study's definition of a "functional cure." None of the participants who received placebo injections achieved the same outcome.
Factors Influencing Response
The researchers also observed that patients entering the trial with lower baseline levels of hepatitis B surface protein were slightly more likely to achieve the functional cure outcome, adding that further studies are underway to understand why response rates vary among patients.
Limitations and Safety
However, Lim noted that the trials did not include patients with cirrhosis, very high surface protein levels, or other complex medical conditions, meaning the results may not apply to all people living with the disease. On durability, he said follow-up data from earlier-stage studies suggested that most patients who achieved viral suppression continued to do well for up to three years after treatment.
He also reported that side effects associated with the drug were generally mild, including injection-site redness or pain and temporary elevations in liver enzymes, which may indicate short-term liver stress.
