GSK Files NDA for Bepirovirsen in Japan for Chronic Hepatitis B

GSK Files NDA for Bepirovirsen in Japan for Chronic Hepatitis B

By, Admin 27 February 2026

GSK plc has taken a key regulatory step in Japan. The company announced that Japan’s Ministry of Health, Labour and Welfare has accepted a new drug application (NDA) for bepirovirsen.

The investigational therapy is being reviewed for the treatment of adults with chronic hepatitis B (CHB).

Why Chronic Hepatitis B Still Matters?

Chronic hepatitis B remains a major global health burden.

  • Affects over 250 million people worldwide
  • Nearly one million patients in Japan
  • Causes approximately 1.1 million deaths annually
  • Linked to about 56% of liver cancer cases globally

Despite available treatments, progress toward cure has been limited.

The Limits of Current Standard of Care

Today’s standard treatment relies on nucleos(t)ide analogues (NAs).

  • Often requires lifelong therapy
  • Functional cure rates are typically around 1%
  • Viral suppression does not always restore immune control

This creates a clear unmet medical need.

What “Functional Cure” Means in Hepatitis B?

Functional cure is a critical benchmark in CHB treatment.

It occurs when:

  • Hepatitis B virus DNA becomes undetectable
  • Hepatitis B surface antigen (HBsAg) remains undetectable
  • These levels persist for at least 24 weeks after stopping therapy

Achieving this significantly reduces long-term risks, including liver cancer.

Phase III Data Behind the NDA

The Japan filing is supported by positive Phase III data from B-Well 1 and B-Well 2.

Trial design highlights

  • Global, multi-centre, randomised, double-blind studies
  • Conducted across 29 countries
  • Enrolled non-cirrhotic CHB patients on NA therapy

Key outcomes

  • Statistically significant functional cure rates
  • Superior results versus standard of care alone
  • Stronger effects in patients with lower baseline HBsAg levels
  • Safety and tolerability consistent with earlier studies

Data presentation and peer-reviewed publication are expected in 2026.

SENKU Designation Accelerates Review in Japan

Bepirovirsen received SENKU designation in Japan in August 2024. This designation:

  • Recognises high innovation
  • Targets serious diseases with unmet need
  • Enables an expedited regulatory review pathway

It is designed to bring promising therapies to patients faster.

How Bepirovirsen Works?

Bepirovirsen is a triple-action antisense oligonucleotide (ASO).

It is designed to:

  • Destroy viral mRNA and pregenomic RNA
  • Inhibit viral replication
  • Reduce circulating HBsAg levels
  • Stimulate immune system re-engagement

The goal is durable immune control without continuous medication.

A Backbone for Future Hepatitis B Regimens

Beyond monotherapy, bepirovirsen is being evaluated as a backbone treatment.

Future strategies may:

  • Combine sequential therapies
  • Expand functional cure to broader patient populations
  • Redefine long-term CHB management

Global Development and Regulatory Recognition

GSK licensed bepirovirsen from Ionis and continues to collaborate on its development.

The therapy has received multiple regulatory designations:

  • Fast Track from the US Food and Drug Administration
  • Breakthrough Therapy designation in China
  • SENKU designation in Japan

Bepirovirsen is not yet approved in any market.

The Bigger Picture

For hepatitis B, suppression is no longer enough. Functional cure is the new benchmark.

With its Japan NDA now under review, bepirovirsen moves one step closer to reshaping how chronic hepatitis B is treated worldwide.

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