Chronic hepatitis B has been considered incurable for decades: existing antiviral medications must be taken for life and achieve functional cure in fewer than one percent of patients. That may change in October 2026. GSK and Ionis Pharmaceuticals published positive results from two Phase III trials of the drug bepirovirsen in January 2026. The US Food and Drug Administration is reviewing the application, with a target decision date of October 26, 2026.
254 Million Affected, Barely Any Cures
About 254 million people worldwide live with chronic hepatitis B. The virus persistently infects liver cells and can remain asymptomatic for decades, yet it causes approximately 820,000 deaths each year through liver cirrhosis and hepatocellular carcinoma, according to WHO data. The treatment gap is stark: only 13 percent of those infected have received a diagnosis, and only three percent are receiving antiviral treatment.
Standard medications from the class of nucleoside analogues effectively suppress viral replication but cannot permanently clear the virus. A functional cure, defined as stable loss of the hepatitis B surface antigen (HBsAg) with undetectable viral load following a finite treatment course, is achieved with these drugs in fewer than one percent of cases. The only notable alternative, pegylated interferon, achieves eight to fourteen percent but comes with significant side effects and requires months of treatment.
How Bepirovirsen Works
Bepirovirsen takes a different approach. As an antisense oligonucleotide, it binds directly to hepatitis B virus RNA and prevents the production of viral proteins, including HBsAg. In a Phase IIb trial with 227 participants, nine to ten percent of patients achieved durable functional cure after a 24-week course at 300 mg weekly. That is roughly ten times the standard therapy rate.
The Phase III programs B-Well 1 and B-Well 2 enrolled more than 1,800 patients across 29 countries. Both studies were randomized, double-blind and placebo-controlled, enrolling patients with chronic hepatitis B on stable nucleoside analogue therapy. In January 2026, GSK and Ionis reported that both studies met their primary endpoints. Bepirovirsen demonstrated statistically significant and clinically meaningful functional cure rates compared to standard therapy alone. In patients with lower baseline HBsAg levels below 1,000 IU/ml, the effect was more pronounced. The companies plan to release specific percentages at the European Association for the Study of the Liver (EASL) congress in May 2026, alongside a peer-reviewed publication.
Accelerated Approval Pathway
The FDA has granted bepirovirsen multiple special designations: Fast Track status in February 2024, followed by Breakthrough Therapy Designation and Priority Review. Breakthrough Therapy signals that a drug has the potential to substantially improve on available treatments. With Priority Review, the FDA commits to a six-month review rather than the standard ten months. The target decision date is October 26, 2026.
Parallel applications are under review at the European Medicines Agency, China's National Medical Products Administration and Japan's Ministry of Health, Labour and Welfare, which has granted bepirovirsen its SENKU designation. All three agencies are processing independent applications.
EASL in May, FDA in October
The EASL congress in May 2026 will be the first public disclosure of the complete trial results, including the actual cure rates. If those numbers confirm the Phase IIb findings, the discussion will immediately turn to pricing and access. A drug that offers a finite, potentially curative course rather than lifelong daily pills requires fundamentally different health-economic calculations than conventional antivirals. For insurers and health systems, the question is what a one-time cure is worth.
Whether bepirovirsen, if approved by the FDA in October 2026, will be accessible to all 254 million people affected worldwide depends on pricing negotiations that have not yet begun. For the 87 percent of those infected who have not even received a diagnosis, even a successful approval would initially remain a theoretical achievement. Nonetheless, bepirovirsen marks a turning point: for the first time, a drug has demonstrated in a large Phase III trial that chronic hepatitis B can be durably cured with a finite course of treatment.