London, Jan 8, 2026, 09:12 GMT — Regular session
- GSK shares fall as traders digest a late-stage hepatitis B update with key details still to come
- Company also flagged fresh regulatory wins for Shingrix packaging in Europe and depemokimab in Japan
- Next catalysts: JPMorgan Healthcare Conference on Jan. 13; full-year results on Feb. 4
GSK (GSK.L) shares slipped on Thursday as investors weighed upbeat headlines on its experimental hepatitis B therapy against a lack of hard cure-rate data. The stock was down 0.9% at 1,883.5 pence in London trade, after moving between 1,880 and 1,896.5 pence and staying near the top of its 52-week range. 1
GSK said two Phase III trials of bepirovirsen met their primary endpoint — the main goal set before the studies began — and delivered a statistically significant “functional cure” rate on top of standard treatment. A functional cure, as the company defines it, is sustained loss of hepatitis B surface antigen and undetectable virus DNA in the blood for at least 24 weeks after a finite course of treatment, a bar current long-term antivirals rarely reach. Chief Scientific Officer Tony Wood said the result “has the potential to transform treatment goals,” with global regulatory filings planned from the first quarter of 2026. 2
What the market still does not have is the split that drives models: how many patients achieved that sustained response, and in which subgroups. Jefferies analyst Michael Leuchten said the consistency of the Phase III read-out “should open blockbuster potential,” though J.P. Morgan analysts flagged that investors will likely wait for the full dataset before drawing conclusions on broad adoption. GSK has said bepirovirsen could generate more than 2 billion pounds in peak annual sales, an early test for new CEO Luke Miels as the company chases an annual revenue target above 40 billion pounds by 2031. 3
The company also updated investors on its vaccines business on Wednesday, saying the European Commission approved a prefilled syringe presentation of Shingrix, its shingles vaccine. GSK said the new format will roll out across EU countries in 2026, without changing dosing or the product’s indication, and Wood called it “designed to improve ease of administration.” 4
Earlier in the week, GSK said Japan’s health ministry approved Exdensur, its twice-yearly biologic depemokimab, for severe asthma and chronic rhinosinusitis with nasal polyps. Respiratory R&D head Kaivan Khavandi said the decision “could set a new standard of care” for patients there who are not controlled on existing therapies. 5
The stock has been choppy over the past three sessions, rising 4.3% on Tuesday, edging up 0.1% on Wednesday and then easing back on Thursday, according to recent trading data. Wednesday’s intraday high was 1,909.5 pence. 6
Investors now want timing: when the full bepirovirsen data are shown, and whether the safety profile and durability hold up once the details land. On a day like this, a few percentage points in cure rate can matter more than the headline.
But hepatitis B drug development has a long history of late-stage stumbles, and even “statistically significant” can look thin if durability fades or side effects limit use. A slower regulatory path or tougher reimbursement calls would also cap peak-sales hopes.
