New Hep B Drug Achieves Functional Cure in 1 in 5 Patients in Phase III Trials
Bepirovirsen, an antisense oligonucleotide, delivered functional cures in ~20% of chronic hepatitis B patients — a landmark leap over existing therapies.
Summary
A new investigational drug called bepirovirsen has achieved functional cures in roughly one in five chronic hepatitis B patients in two large phase III clinical trials. Published in the New England Journal of Medicine, the B-Well 1 and B-Well 2 trials showed 19-20% of treated patients cleared the hepatitis B surface antigen and suppressed viral DNA for at least 24 weeks after stopping treatment — compared to zero in placebo groups. Current standard therapies achieve this outcome in only 3-11% of patients after years of use. Chronic hepatitis B affects hundreds of millions globally and is a leading cause of liver cirrhosis and liver cancer. This result represents a meaningful advance in the possibility of finite, curative treatment for a historically lifelong managed infection.
Detailed Summary
Chronic hepatitis B virus infection affects an estimated 300 million people worldwide and is a major driver of liver cirrhosis, liver failure, and hepatocellular carcinoma — one of the leading causes of cancer-related death globally. Current therapies suppress the virus but rarely eliminate it, requiring lifelong treatment. A true functional cure has remained an elusive goal, making this new data highly significant.
The B-Well 1 and B-Well 2 phase III trials evaluated bepirovirsen, an antisense oligonucleotide designed to reduce all forms of hepatitis B viral RNA and surface antigen (HBsAg). Across both double-blind trials involving patients from 29 countries, approximately 20% and 19% of bepirovirsen-treated patients achieved functional cure at week 72 — defined as sustained HBsAg loss and undetectable viral DNA for at least 24 weeks off therapy — compared to zero percent in placebo groups. The risk differences were statistically robust (P<0.001 for both trials).
These results dwarf what existing therapies deliver. Nucleoside analogue therapy achieves HBsAg loss in only around 3% of patients after 8-10 years. Pegylated interferon reaches approximately 8-11% after 3 years. Bepirovirsen achieved comparable or superior outcomes in 24 weeks of active treatment, with patients then able to discontinue all antiviral therapy entirely — a major quality-of-life and economic consideration.
For health-conscious adults and clinicians, this signals a potential paradigm shift from indefinite viral suppression to finite curative treatment for a subset of chronic HBV patients. Patients who achieve functional cure no longer require ongoing nucleoside analogue therapy, reducing long-term drug exposure and associated risks.
Important caveats remain. The trials excluded patients with cirrhosis, HIV coinfection, hepatitis C or D coinfection, and those with HBsAg levels above 3,000 IU/mL — limiting generalizability. Long-term durability of HBsAg loss beyond week 72 has not yet been confirmed. Bepirovirsen is still investigational and not yet approved for clinical use.
Key Findings
- Bepirovirsen achieved functional cure in ~20% of chronic hepatitis B patients vs. 0% on placebo in phase III trials.
- Functional cure means sustained HBsAg loss and undetectable viral DNA for 24+ weeks after stopping all antiviral therapy.
- Current standard nucleoside analogue therapy achieves HBsAg loss in only ~3% of patients after 8-10 years of use.
- Results were published simultaneously in the New England Journal of Medicine, supporting high evidence credibility.
- Trial excluded cirrhosis and HIV coinfection patients; durability beyond 72 weeks still requires confirmation.
Methodology
This is a meeting coverage news report from MedPage Today summarizing phase III randomized double-blind placebo-controlled trial results (B-Well 1 and B-Well 2) presented at EASL 2026 and simultaneously published in the New England Journal of Medicine. The source is credible and trial design is rigorous. Evidence basis is strong: dual phase III trials, multinational enrollment, pre-specified endpoints, and peer-reviewed publication.
Study Limitations
Bepirovirsen is still investigational and not yet approved; real-world availability is uncertain. Trial results cannot be generalized to patients with cirrhosis, HIV coinfection, or high HBsAg levels. Long-term durability of functional cure beyond 72 weeks has not yet been established and requires further follow-up data.
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