Investigational Hepatitis B Therapy is Granted FDA Fast-Track Status


GSK’s bepirovirsen received this designation, and the company has its sights on the therapy potentially providing a functional cure for the millions of people around the world who are affected by this form of viral hepatitis.

The FDA has granted a fast-track designation for bepirovirsen, an investigational agent for the treatment of chronic hepatitis B (CHB). Fast track designation is intended to facilitate the development and expedite the review of therapies to treat serious conditions and fill an unmet medical need.1

The therapy’s manufacturer, GSK, had requested designation based on the potential for bepirovirsen to address an unmet medical need for chronic hepatitis B, which can be a serious and life-threatening condition.1

According to the Centers for Disease Control and Prevention (CDC), a total of 14,229 new cases of CHB were reported in the United States in 2021, which equates to a rate of 5.9 cases per 100,000 people. CDC also reports that while the rate of reported acute hepatitis B was the lowest among non-Hispanic Asian/Pacific Islander persons, the rate of newly reported chronic hepatitis B was highest among this patient group in the US.2

From an international standpoint, this form of viral hepatitis affects nearly 300 million people globally, according to the World Health Organization.1

What the Data has Demonstrated

In previous data reports, GSK said 28-29% of patients with chronic hepatitis B has achieved undetectable virus levels after 24 weeks of treatment with bepirovirsen. However this level dropped to 9-10% of patients during a phase 2b trial.3

The study was published in the New England Journal of Medicine, and Contagion reported on the study, noting bepirovirsen sustained the primary efficacy measures of reducing hepatitis B surface antigen (HBsAg) below the lower limit of detection (0.05 IU/ml) and HBV DNA level below the lower limit of quantification (20 IU/ml) for 24 weeks after treatment in approximately 10% of the trial participants with chronic HBV infection. That level of response was more likely with a loading dose, the longer of 2 tested regimens, and lower levels of HBsAg at baseline.3

GSK has stated they are looking at longer term efficacy and durability of response in the B-Sure trial, which follows participants from the B-Clear study for an additional 33 months and includes criteria for stopping nucleoside/nucleotide analogues (NAs) therapy to evaluate the potential for functional cure in patients who successfully stop all medication and continue to demonstrate no serologic evidence of hepatitis B surface antigen (HBsAg) or HBV DNA.1

What You Need to Know

The designation of GSK's bepirovirsen as a fast-track therapy by the FDA for the treatment of chronic hepatitis B indicates that the therapy has shown promise in addressing an unmet medical need for this serious condition.

Clinical data indicates that bepirovirsen has shown promising results in reducing hepatitis B surface antigen (HBsAg) levels and suppressing viral replication in patients with chronic hepatitis B, suggesting its potential as a functional cure when combined with oral nucleoside/nucleotide analogues (NAs).

GSK is looking at this therapy as a potential functional cure for chronic hepatitis.

The Agent

Bepirovirsen is an antisense oligonucleotide (ASO) and is the only single agent in phase 3 development that has shown the potential to achieve clinically meaningful functional cure response when combined with oral NAs, according to GSK. This claim was demonstrated by positive results in the B-Clear and B-Sure clinical trials. B-Clear identified that patients with low baseline hepatitis B surface antigen levels are most likely to benefit from treatment with bepirovirsen. Bepirovirsen is also being investigated as a potential backbone therapy in future sequential regimens to pursue functional cure in a broader population of patients with CHB.1

Bepirovirsen inhibits the replication of viral DNA in the body, suppresses the level of hepatitis B surface antigen (HBsAg) in the blood, and stimulates the immune system to increase the chances of a durable and sustained response. The agent, (previously known as ISIS 505358 or IONIS-HBVRX), was discovered by and jointly developed with Ionis Pharmaceuticals.

At last year’s JP Morgan Healthcare Conference, GSK said bepirovirsen had the “potential to be first in-class functional cure for chronic HBV.”3


1.GSK receives US FDA Fast Track designation for bepirovirsen in chronic hepatitis B. GSK press release. February 12, 2024. Accessed February 13, 2024.

2.Hepatitis B. CDC. Reviewed August 7, 2023. Accessed February 13, 2024.,5.9%20cases%20per%20100%2C000%20people.

3.Parkinson J. GSK Investigational Hepatitis Therapy Will Begin Phase 3 Trials. ContagionLive. March 5, 2023. Accessed February 13, 2024.

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