Hibsago (bepirovirsen) approved in Canada as the first and only finite therapy indicated to achieve functional cure of chronic hepatitis B

• Hibsago was reviewed under Health Canada's Priority Review policy, reflecting its innovation and potential to address a disease with high unmet medical need

• Approval is based on data from Phase III B-Well trials which demonstrated significant and clinically meaningful functional cure rates

• An estimated 262,000 people in Canada live with chronic hepatitis B1, a leading cause of liver cancer²

MISSISSAUGA, ON - GSK announced today that Health Canada has approved Hibsago (bepirovirsen) as a finite treatment to achieve functional cure of chronic hepatitis B (CHB) virus infection in non-cirrhotic adult patients who have been on nucleos(t)ide analogue therapy for at least 6 months and with HBV DNA <90 IU/mL, and have hepatitis B surface antigen (HBsAg) levels ≤3,000 IU/mL. Clinical efficacy is higher with lower baseline HBsAg levels, especially in patients with baseline HBsAg levels ≤1,000 IU/mL.³ Hibsago is an antisense oligonucleotide (ASO) and the first and only therapy in Canada with an indication to achieve functional cure in CHB.

"Hibsago's authorization in Canada represents an important step forward for people living with CHB, a serious, progressive liver disease," says Dr. Michelle Horn, Country Medical Director, GSK Canada. "The possibility of a functional cure delivered through a finite course of therapy changes expectations from lifelong management to the prospect of stopping treatment and supporting long-term liver health. CHB remains an area of high unmet need, and GSK remains committed to advancing hepatology to help address this gap for Canadians living with this disease."

Approval in Canada was supported by results from the B-Well phase III trials showing unprecedented functional cure rates of 19% in adults with ≤3000 IU/ml baseline HBsAg and 26% in adults with baseline HBsAg ≤1000 IU/ml, compared with 0% functional cure in the placebo (standard-of-care alone) group.⁴ Functional cure occurs when the hepatitis B virus DNA and viral protein - HBsAg - are undetectable for at least 24 weeks after stopping all hepatitis B treatment. This indicates the disease is controlled by the immune system without medication.

"For many people in Canada living with CHB, the diagnosis comes with years of worry about liver damage and the impact on work, family and future plans, and it can still carry stigma and misunderstanding in their communities," added Jennifer Nebesky, CEO, Liver Canada. "New options like Hibsago can offer people living with CHB greater confidence about their liver health and help us tackle the ongoing challenges that still affect the CHB community across Canada."

CHB is a long-term viral infection, which affects an estimated 262,000 people in Canada.¹ It often goes undetected for years because many people have few or no symptoms, but over time it can lead to serious liver damage, including cirrhosis and liver cancer.²

Hibsago's approval in Canada was granted under Health Canada's Priority Review policy, reflecting its innovation and potential to address a disease with high unmet medical need. It follows authorizations in Japan and the United States.

Hibsago supply is anticipated to become available in Canada to eligible patients in early 2027.

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 an estimated 262,000 people in Canada. The disease causes approximately 1.1 million deaths each year globally.¹ In people with chronic hepatitis B, a loss in hepatitis B surface antigen is associated with up to an 89% reduction in risk of liver cancer and a 62% reduction in risk of all-cause mortality.⁵

Many patients require lifelong antiviral therapy for viral suppression, making functional cure a critical goal in disease management. The Canadian Association for the Study of the Liver (CASL) and the Association of Medical Microbiology and Infectious Disease Canada (AMMI) updated guidelines identify functional cure as the optimal goal of treatment.⁶

About Hibsago (bepirovirsen)

Hibsago (bepirovirsen) is an antisense oligonucleotide (ASO) designed to recognise and inhibit the production 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. Hibsago reduces the production of RNA and viral proteins associated with HBV, 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 Hibsago (bepirovirsen) from Ionis Pharmaceuticals and collaborated with them on its development.

Please consult the Hibsago product monograph at gsk.ca for complete safety information. The product monograph is also available by calling 1-800-387-7374.

About B-Well Clinical trial programs

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. Functional cure in patients with baseline HBsAg ≤1000 IU/ml was a key secondary endpoint. Functional cure was defined as sustained suppression (24 weeks or longer) of HBV DNA (<LLOQ) and HBsAg not detected, with or without hepatitis B surface antibodies, after a finite duration of therapy with bepirovirsen and off all HBV treatment.

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.ca.

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 2025, and GSK's Q3 Results for 2026.

References

1 Public Health Agency of Canada. Canada's progress towards eliminating viral hepatitis as a public health concern. https://www.canada.ca/en/public-health/services/publications/diseases-conditions/progress-towards-eliminating-viral-hepatitis-threat-2021.html

2 World Health Organization. Global hepatitis report 2026. Available at: https://www.who.int/publications/i/item/9789240122383. Last accessed: June 2026

3 Hibsago product monograph.

4 Hou J, Lim SG, Buti M, et al. Phase 3 results of bepirovirsen treatment for chronic hepatitis B virus infection. N Engl J Med. 2026;394:2395-2406. doi:10.1056/NEJMoa2515131

5 Drysdale M, Chang R, Wang S, Coutinho A, Gielen V, Man T, Song R, Duh MS, Khalili M, Theodore D. Hepatitis B Surface Antigen Loss and Improved Clinical Outcomes in US Individuals With Chronic Hepatitis B Virus Infection. J Viral Hepat. 2026 Jun;33(6):e70184. doi: 10.1111/jvh.70184. PMID: 42141794; PMCID: PMC13179525.

6 The management of chronic hepatitis B: 2025 Guidelines update from the Canadian Association for the Study of the Liver and Association of Medical Microbiology and Infectious Disease Canada