REG - GSK PLC - Bepirovirsen accepted for Japan regulatory review

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RNS Number : 4530U  GSK PLC  26 February 2026

Issued: 26(th) February 2026, London UK

 

Bepirovirsen accepted for regulatory review in Japan as a potential
first-in-class treatment for chronic hepatitis B

 

·   Submission supported by statistically significant and clinically
meaningful functional cure rates demonstrated in pivotal phase III B-Well
trials

·   Nearly 1 million people in Japan live with chronic hepatitis B 1 
(#_edn1) , a leading cause of liver cancer 2  (#_edn2)

·   First regulatory filing globally, with SENKU designation enabling
expedited review 3  (#_edn3)

 

GSK plc (LSE/NYSE: GSK) today announced that Japan's Ministry of Health,
Labour and Welfare (MHLW) has accepted for review a new drug application (NDA)
for bepirovirsen, an investigational antisense oligonucleotide (ASO), for the
treatment of adults with chronic hepatitis B (CHB).

 

Chronic hepatitis B is a major public health challenge, affecting more than
250 million people worldwide and nearly one million people in Japan.(1) The
current standard of care - nucleos(t)ide analogues - often requires lifelong
therapy and the functional cure rates remain low, typically only 1%.(( 4 
(#_edn4) )) Functional cure occurs when the hepatitis B virus DNA and viral
protein - hepatitis B surface antigen (HBsAg) - are at levels low enough to be
undetectable in the blood for at least 24 weeks after stopping all treatment,
and can be controlled by the immune system without medication. Functional cure
is associated with significant reduction in the risk of long-term liver
complications, including liver cancer.(( 5  (#_edn5) )) It is estimated that
~56% of liver cancer cases globally are caused by CHB.(2)

The regulatory submission is supported by positive results from the B-Well 1
and B-Well 2 Phase III trials, where bepirovirsen demonstrated a statistically
significant and clinically meaningful functional cure rate. Functional cure
rates were significantly higher with bepirovirsen plus standard of care
compared with standard of care alone across all ranked endpoints, including in
patients with lower baseline HBsAg levels where an even greater effect was
observed. Bepirovirsen demonstrated an acceptable safety and tolerability
profile consistent with previous studies.(( 6  (#_edn6) )) The data are
anticipated to be presented at a congress and submitted for scientific
peer-reviewed publication in 2026.

Bepirovirsen was granted SENKU designation in Japan(3) in August 2024,
reflecting its innovation and potential to address a disease with high unmet
medical need. SENKU designation is intended to facilitate early patient access
through an expedited regulatory review process.

 

Clinical trial programme

B-Well 1  NCT05630807  and B-Well 2 [NCT 05630820] trials are global
multi-centre, randomised, double-blind, placebo-controlled trials conducted in
29 countries. They assessed the efficacy, safety, pharmacokinetic profile, and
the durability of functional cure in nucleos(t)ide analogue (NA)-treated in
non-cirrhotic participants with CHB and baseline surface antigen (HBsAg)
≤3000 IU/ml. The primary endpoint assessed the proportion of participants
achieving functional cure in patients with baseline surface antigen (HBsAg)
≤3000 IU/ml. A key ranked secondary endpoint evaluated functional cure in
patients with baseline HBsAg ≤1000 IU/ml.

 

About chronic hepatitis B

Hepatitis B is a viral infection that can cause both acute and chronic liver
disease. Chronic hepatitis B occurs when the immune system is unable to clear
the virus, resulting in long-lasting infection that affects more than 250
million people worldwide. The disease causes approximately 1.1 million deaths
each year(( 7  (#_edn7) )), and approximately 4000 deaths in Japan
annually.(1) Many patients often require lifelong antiviral therapy for viral
suppression; making functional cure a critical goal in disease management.

 

About bepirovirsen

Bepirovirsen is a triple action investigational antisense oligonucleotide
(ASO), designed to recognise and orchestrate the destruction of the genetic
components (i.e. mRNA and pregenomic RNA) of the hepatitis B virus that can
lead to chronic disease, potentially allowing a person's immune system to
regain control. Bepirovirsen inhibits the replication of the viral genome 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.

 

Bepirovirsen is also being evaluated as a potential backbone therapy for
future sequential treatment strategies aimed at expanding functional cure to
broader patient populations.

 

GSK licensed bepirovirsen from Ionis and collaborated with them on its
development. Bepirovirsen has been recognised by global regulatory authorities
for its innovation and potential to address significant unmet need in
hepatitis B, with Fast Track designation from the US FDA, Breakthrough Therapy
designation in China and SENKU designation in Japan. Bepirovirsen is currently
not approved anywhere in the world.

 

About GSK

GSK is a global biopharma company with a purpose to unite science, technology,
and talent to get ahead of disease together. Find out more at www.gsk.com
(https://www.gsk.com) .

 

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Cautionary statement regarding forward-looking statements

GSK cautions investors that any forward-looking statements or projections made
by GSK, including those made in this announcement, are subject to risks and
uncertainties that may cause actual results to differ materially from those
projected. Such factors include, but are not limited to, those described in
the "Risk Factors" section in GSK's Annual Report on Form 20-F for 2024, and
GSK's Q4 Results for 2025.

 

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 1  (#_ednref1) Polaris Observatory Dashboard. Available at
https://cdafound.org/polaris/dashboard/
(https://cdafound.org/polaris/dashboard/) (last accessed January 2026).

 2  (#_ednref2) Rumgay H et al . Global burden of primary liver cancer in 2020
and predictions to 2040. J Hepatol. 2022;77:1598-1606. doi:
10.1016/j.jhep.2022.08.021

 3  (#_ednref3) GSK Press release, Bepirovirsen granted SENKU designation in
Japan for chronic hepatitis B, August 2024. Available at:
https://www.gsk.com/en-gb/media/press-releases/bepirovirsen-granted-senku-designation-in-japan-for-chronic-hepatitis-b/
(https://www.gsk.com/en-gb/media/press-releases/bepirovirsen-granted-senku-designation-in-japan-for-chronic-hepatitis-b/)
(last accessed: January 2026).

(( 4  (#_ednref4) )) Slaets, L. et al. "Systematic review with meta-analysis:
hepatitis B surface antigen decline and seroclearance in chronic hepatitis B
patients on nucleos(t)ide analogues or pegylated interferon therapy" in
GastroHep 2, 106-116 (2020)

 5  (#_ednref5) EASL, "Clinical Practice Guidelines on the management of
hepatitis B virus infection" in Journal of Hepatology Volume 83, Issue 2,
August 2025, Pages 502-583. Available at:
https://www.sciencedirect.com/science/article/pii/S0168827825001746  (last
accessed: January 2026).

 6  (#_ednref6) GSK Press release, GSK announces positive results from B-Well
1 and B-Well 2 phase III trials for bepirovirsen, a potential first-in-class
treatment for chronic hepatitis B, January 2026. Available at:
https://www.gsk.com/en-gb/media/press-releases/gsk-announces-positive-results-from-b-well-1-and-b-well-2-phase-iii-trials-for-bepirovirsen-a-potential-first-in-class-treatment-for-chronic-hepatitis-b/
(https://www.gsk.com/en-gb/media/press-releases/gsk-announces-positive-results-from-b-well-1-and-b-well-2-phase-iii-trials-for-bepirovirsen-a-potential-first-in-class-treatment-for-chronic-hepatitis-b/)
(last accessed: January 2026).

 7  (#_ednref7) WHO. Global hepatitis report 2024. Available at:
https://www.who.int/publications/i/item/9789240091672
(https://www.who.int/publications/i/item/9789240091672) (last accessed:
January 2026).

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