GSK plc has reported positive results from two pivotal phase III clinical trials evaluating bepirovirsen, an investigational antisense oligonucleotide therapy for chronic hepatitis B (CHB), marking a significant development in a disease area with limited curative options. The studies, known as B-Well 1 and B-Well 2, enrolled more than 1,800 patients across 29 countries, making them among the largest late-stage trials conducted in CHB to date.
Chronic hepatitis B remains a major global health burden, affecting over 250 million people worldwide and accounting for more than half of all liver cancer cases. Despite the availability of nucleos(t)ide analogue therapies, most patients require lifelong treatment, and functional cure rates remain low, typically around 1%. A functional cure is defined as sustained loss of hepatitis B surface antigen (HBsAg) and undetectable hepatitis B virus DNA for at least 24 weeks after completing a finite course of therapy, allowing the immune system to control the infection without ongoing medication.
According to GSK, both B-Well trials met their primary endpoints, demonstrating statistically significant and clinically meaningful functional cure rates with bepirovirsen when added to standard of care, compared with standard therapy alone. The results were consistent across all ranked endpoints, including in patients with lower baseline HBsAg levels (≤1000 IU/ml), where the treatment effect was even more pronounced. The safety and tolerability profile of bepirovirsen was reported to be acceptable and consistent with findings from earlier studies.
Tony Wood, Chief Scientific Officer at GSK, described the results as potentially transformative. He noted that achieving meaningful functional cure rates represents a first for chronic hepatitis B and could redefine treatment goals for patients. Wood added that the data support GSK’s plans to advance bepirovirsen not only as a standalone therapy but also as a potential backbone for future sequential treatment strategies within its growing hepatology pipeline.
Full trial results will be submitted for presentation at an upcoming scientific congress and published in a peer-reviewed journal. GSK also plans to use the data to support regulatory submissions to health authorities worldwide. If approved, bepirovirsen could become the first finite, six-month therapeutic option for chronic hepatitis B, offering an alternative to lifelong antiviral suppression.
Bepirovirsen is a triple-action antisense oligonucleotide designed to target and degrade hepatitis B viral RNA, suppress viral replication, reduce circulating HBsAg levels, and stimulate immune responses that may lead to durable disease control. GSK licensed the therapy from Ionis Pharmaceuticals and has collaborated with Ionis on its development.
The drug has already received several regulatory recognitions, including Fast Track designation from the US Food and Drug Administration, Breakthrough Therapy designation in China, and SENKU designation in Japan, reflecting its potential to address a significant unmet need in chronic hepatitis B treatment.