REG - GSK PLC - Positive phase 3 data for GSK's bepirovirsen

GSKAnnouncement

Wed 07:00

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RNS Number : 8984N  GSK PLC  07 January 2026

Issued: 7 January 2026, London UK

 

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

 

·   Primary endpoint met in both trials

·   Bepirovirsen demonstrated a statistically significant and clinically
meaningful functional cure rate

·   Chronic hepatitis B (CHB) accounts for ~56% of liver cancer cases 1 
(#_edn1) and affects more than 250 million people worldwide 2  (#_edn2)

·   Global regulatory filings planned from Q1 2026

 

 

GSK plc (LSE/NYSE: GSK) today announced positive results from its two pivotal
phase III trials, B-Well 1  NCT05630807  and B-Well 2 [NCT 05630820],
evaluating bepirovirsen, an investigational antisense oligonucleotide (ASO)
for the treatment of chronic hepatitis B (CHB) in over 1,800 patients from 29
countries.

 

CHB is a major health challenge affecting over 250 million people worldwide
and is the leading cause of liver cancer. The current standard of care -
nucleos(t)ide analogues - often requires lifelong therapy and the functional
cure rates remain low, typically only 1%. 3  (#_edn3) Functional cure for CHB
is when the virus can no longer be detected in the blood, as measured by the
sustained loss of hepatitis B surface antigen - a viral protein that signals
ongoing infection - and undetectable hepatitis B virus DNA for at least 24
weeks after a finite course of treatment. This allows the immune system to
control the infection without further medication.  Functional cure is
associated with significant reduction in the risk of long-term liver
complications, including liver cancer, as well as all -cause mortality. 4 
(#_edn4) (,  5  (#_edn5) )

 

The B-Well trials met their primary endpoint, and 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. Results were
statistically significant across all ranked endpoints, including in patients
with baseline surface antigen (HBsAg) <=1000 IU/ml where an even greater
effect was demonstrated.  The trials demonstrated an acceptable safety and
tolerability profile consistent with what was reported in other studies.

 

Tony Wood, Chief Scientific Officer, GSK, said:

"Bepirovirsen has the potential to transform treatment goals for people living
with CHB by achieving significant functional cure rates - a first for the
disease. CHB affects more than 250 million people and leads to approximately
56% of liver cancer cases worldwide. Today's result supports our plans to
progress bepirovirsen as a treatment and also continue its development as a
backbone in future sequential therapies. We're pleased by this major advance
in our expanding hepatology pipeline, aimed to transform outcomes in liver
disease."

 

Full results will be submitted for presentation at an upcoming scientific
congress, published in a peer-reviewed journal and used to support regulatory
submissions to health authorities worldwide. If approved, bepirovirsen has the
potential to become the first finite, six-month therapeutic option for CHB and
to serve as a backbone for future sequential treatment strategies.

 

Clinical trial programme

B-Well 1 and B-Well 2 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 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 participants with baseline HBsAg ≤1000
IU/ml. Functional cure is defined as hepatitis B surface antigen (HBsAg) loss
and undetectable HBV DNA for at least 24 weeks after a finite course of
treatment.

 

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 6  (#_edn6) , and accounts for approximately 56% of liver cancer
cases globally. 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. 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 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.

 

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.

 

 

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 gsk.com.

 

 GSK enquiries
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 Investor Relations:  Constantin Fest    +44 (0) 7831 826525   (London)
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                      Jeff McLaughlin    +1 215 751 7002       (Philadelphia)
                      Frannie DeFranco   +1 215 751 3126       (Philadelphia)

 

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 Q3 Results for 2025.

 

Registered in England & Wales:

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Registered Office:

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WC1A 1DG

 

(#_ednref1) (1) 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

(( 2  (#_ednref2) )) 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)

(( 3  (#_ednref3) )) 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)

(( 4  (#_ednref4) )) Drysdale M et al. GHS 2025. Oral presentation. Slides
available upon request.

 5  (#_ednref5) EASL, "Clinical Practice Guidelines on the management of
hepatitis B virus infection" in Journal of Hepatology
(https://www.sciencedirect.com/journal/journal-of-hepatology)

Volume 83, Issue 2
(https://www.sciencedirect.com/journal/journal-of-hepatology/vol/83/issue/2)
, August 2025, Pages 502-583. Available at:
https://www.sciencedirect.com/science/article/pii/S0168827825001746
(https://www.sciencedirect.com/science/article/pii/S0168827825001746) (last
accessed: January 2026)

 6  (#_ednref6) WHO. Global hepatitis report 2024. Available at:
https://www.who.int/publications/i/item/9789240091672 (last accessed: January
2026)

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