LONDON, UK, May 28, 2026
GSK has announced groundbreaking Phase III clinical trial results for bepirovirsen, its investigational antisense oligonucleotide (ASO) therapy for chronic hepatitis B (CHB), demonstrating functional cure rates that could significantly transform the treatment landscape for one of the world’s most prevalent chronic viral infections. Data from the pivotal B-Well 1 and B-Well 2 studies, simultaneously presented at the European Association for the Study of the Liver (EASL) Congress 2026 and published in the New England Journal of Medicine, revealed unprecedented functional cure rates far exceeding those achieved with current standard-of-care therapies. With more than 240 million people worldwide living with chronic hepatitis B, the findings mark a major milestone in the pursuit of finite therapies capable of achieving long-term disease control without lifelong treatment.
Phase 3 Trials Achieve Significant Functional Cure Rates
The pooled Phase III data demonstrated that 19% of patients receiving bepirovirsen achieved a functional cure, compared with 0% in the placebo group, successfully meeting the primary endpoint of both studies. Among patients with lower baseline hepatitis B surface antigen (HBsAg) levels of ≤1000 IU/mL, the functional cure rate increased to an impressive 26%, highlighting the therapy’s potential in a substantial proportion of the global hepatitis B population.
Functional cure is defined as sustained clearance of hepatitis B virus DNA and hepatitis B surface antigen for at least six months after treatment discontinuation, allowing the immune system to maintain control of the disease without ongoing medication. Importantly, current standard therapies generally achieve functional cure rates of less than 1%, making the Phase III outcomes one of the most significant advances reported in chronic hepatitis B treatment in recent years. The trials enrolled participants across 29 countries, reinforcing the robustness and global relevance of the findings.
Bepirovirsen Shows Durable Responses and Promising Safety Profile
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Beyond the primary endpoint, bepirovirsen demonstrated encouraging long-term efficacy. An exploratory analysis showed that 49% of treated patients achieved hepatitis B surface antigen levels of ≤100 IU/mL one year after completing therapy, a biomarker associated with improved immune control and favorable clinical outcomes. Additionally, 23% of all treated participants achieved sustained viral suppression at Week 72, while the rate increased to 31% among patients with lower baseline HBsAg levels.
Researchers noted that loss of hepatitis B surface antigen is associated with an 89% reduction in liver cancer risk and a 62% reduction in all-cause mortality, underscoring the broader clinical significance of achieving functional cure. Safety findings were consistent with previous studies, with the most commonly reported adverse events including injection-site redness, localized pain, and temporary elevations in liver enzyme levels. Overall, investigators reported an acceptable safety and tolerability profile supporting the therapy’s continued regulatory advancement.
Regulatory Momentum Builds for Potential First-in-Class Therapy
Bepirovirsen is currently under Priority Review by the U.S. Food and Drug Administration, supported by both Breakthrough Therapy and Fast Track designations. Regulatory submissions are also under review in Europe, Japan, and China, where the therapy has received multiple expedited review pathways recognizing its potential to address a major unmet medical need. GSK anticipates initial regulatory decisions during the third quarter of 2026, while launch preparations are already underway globally. The company recently entered a strategic collaboration in China aimed at accelerating patient access following approval.
As healthcare systems increasingly prioritize functional cure as the ultimate treatment goal for chronic hepatitis B, the Phase III success of bepirovirsen positions the therapy as a potential first-in-class innovation capable of redefining disease management. If approved, the therapy could provide millions of patients worldwide with a realistic opportunity to achieve durable viral control and reduce the long-term risks of liver cirrhosis, liver failure, and hepatocellular carcinoma, representing one of the most important advances in hepatology in the past decade.
Source: GSK press release
