GSK's Hepatitis B Drug Achieves Functional Cure in 20% of Patients in Key Studies

• Functional cure rate reached 19% overall for patients with surface antigen levels at or below 3,000 IU/ml, and 26% for those at or below 1,000 IU/ml, exceeding analyst expectations of 15-20%
• Over 250 million people globally have chronic hepatitis B, but current standard treatments achieve sustained viral clearance in only 1-4% of patients, making this a significant unmet need
• The drug requires only six months of injections compared to lifelong daily pills, with side effects primarily limited to mild injection-site reactions

Summary

GSK Hepatitis B Drug Shows Promising Results in Late-Stage Studies

GSK announced that its experimental hepatitis B drug, bepirovirsen, achieved a functional cure in 19% of patients across two late-stage clinical studies. The results were presented at a medical conference on May 28, exceeding analyst expectations of a 15-20% response rate.

Key Clinical Data:

• 19% of patients with surface antigen levels ≤3,000 IU/ml achieved functional cure after six months of treatment
• Response rate increased to 26% among patients with levels ≤1,000 IU/ml
• Functional cure defined as undetectable hepatitis B virus DNA and surface antigen levels for at least six months post-treatment
• Treatment generally well-tolerated with mostly mild injection-site reactions

Market Context:

More than 250 million people globally suffer from chronic hepatitis B. Current standard treatments only help 1-4% of patients clear the virus sustainably. Existing nucleotide analogue therapies typically require lifelong use and suppress rather than eliminate the virus.

Financial Implications:

Bepirovirsen is central to GSK's long-term growth strategy, with the company targeting over £40 billion ($54 billion) in annual revenue by 2031. GSK expects the drug to generate peak annual sales exceeding £2 billion.

Regulatory Timeline:

GSK has filed for approval in the U.S., Japan, China, and Europe. A U.S. FDA decision is expected by October 26, 2025, with Japanese regulatory decisions also anticipated this year.

The six-month finite treatment course represents a significant advancement over current lifelong therapy options, potentially transforming hepatitis B management.