GSK experimental hepatitis B treatment delivered 'functional cure' to roughly one in five patients
An experimental hepatitis B treatment developed by British drugmaker GSK has produced a long-awaited result in clinical trials. According to STAT News's clinical data report, the treatment delivered what is defined as a 'functional cure' in about one in five patients. That means hepatitis B surface antigen (HBsAg) falls to undetectable levels in the blood and the virus is suppressed even after the drug is withdrawn.
The concept of a functional cure carries particular weight in hepatitis B treatment. STAT News notes that even after years of antiviral therapy in chronic hepatitis B cases, the functional cure rate has traditionally sat between 1 and 3 percent. In the GSK Phase 2b trial that rate reached 22 percent, generating significant hope among hepatologists. This is also the moment when Phase 3 work is being designed and FDA and EMA review processes are about to begin.
Chronic hepatitis B affects about 296 million people worldwide and is responsible for an estimated 820,000 deaths each year. WHO data show that the majority of cases are in Asia and Sub-Saharan Africa, though rates in high-income countries are also notable because of migrant populations. Existing antiviral treatments can suppress viral replication but patients are typically dependent on life-long therapy. That dependency creates a long-term burden on health systems from drug pricing and adherence.
How the GSK treatment works is among the details. The therapy combines an RNA-based small interfering RNA (siRNA) with a conventional antiviral. The siRNA component targets the mRNA molecule involved in virus production, blocking HBsAg production. Massachusetts General Hospital hepatologist Dr Jenny Heathcote told STAT News that this mechanism is 'the natural continuation of earlier gene-silencing work, but the magnitude of clinical effect is an unexpected result.'
Looking at trial details, 280 patients were followed for 48 weeks. Among the 200 patients in the treatment arm who received the combination, functional cure was achieved in 22 percent; in the 80-patient control arm only 3 percent reached that result. The side-effect profile is relatively favourable: patients experienced upper respiratory infection, headache and fatigue, with the serious adverse event rate at about 4 percent. No liver failure or other serious systemic adverse events were reported in any patient.
Access to the treatment in lower-income countries is at the centre of the debate. STAT News spoke with Dr Stefan Wiktor, a former WHO hepatitis programme director, who said: 'A cure-providing therapy may carry an annual price tag above 100,000 dollars in the Western market; but GSK's patent-sharing strategy could pull the annual price into the 500-1,000 dollar range for lower-income countries.' Preliminary discussions between GSK, the Serum Institute of India and other generic manufacturers have reportedly begun on this point.
Financial markets responded too. GSK shares rose 4 percent on the London exchange after the news spread; analysts calculated the treatment's potential annual market at 4-6 billion dollars. Goldman Sachs analyst Akeel Adkins published a note stating: 'If Phase 3 results come out at similar calibre, GSK has the capacity to generate an additional 3 billion dollars of annual revenue by 2028.' This article is not investment advice; the data are taken from GSK's official disclosure and STAT News's market analysis report.
Other reactions from the research community are notable. Stanford University hepatology chair Dr Aijaz Ahmed said: 'This result is the first large-scale Phase 2 data set showing that hepatitis B can truly be treated.' By contrast, Dr Heather Lewis of Imperial College London offered a cautious view: 'Whether the functional cure response remains stable across long follow-up and what relapse rates will look like are questions that still await answers.'
By GSK's reckoning the Phase 3 study will begin in 2026 with 800 patients at 24 sites worldwide. According to STAT News, the FDA in the US has begun the review for granting the treatment 'Breakthrough Therapy' status, which is given to therapies that provide significant progress for life-threatening diseases and can shorten the approval process by an average of 6-12 months.
This article is not medical advice; please consult a healthcare professional for personal health decisions. If you are a hepatitis B carrier or chronic patient, do not change your current treatment until GSK's new therapy is available. The clinical research process is long and results may change; actual access to the treatment is not expected on a broad scale before 2028.