GSK and Ionis Present Promising Hepatitis B Drug Data
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GSK and Ionis have unveiled significant data on their hepatitis B drug, presenting a potential functional cure. This development could reshape treatment strategies in the pharmaceutical industry.
GSK and Ionis advanced hepatitis B care when Phase 3 B-Well 1 and B-Well 2 showed bepirovirsen delivered statistically higher functional cure rates than placebo after nucleoside analogue therapy, with peer-reviewed detail published in the New England Journal of Medicine.
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Key Takeaways
- B-Well 1 (NCT05630807) and B-Well 2 (NCT05630820) met primary endpoints for functional cure at week 72 after finite bepirovirsen dosing.
- NEJM reported functional cure in 20% (127/650) vs 0% (0/328) in B-Well 1 and 19% (106/570) vs 0% (0/286) in B-Well 2.
- Bepirovirsen is an antisense oligonucleotide licensed by GSK from Ionis; FDA previously granted Fast Track for chronic hepatitis B.
- Grade 3+ adverse events were more common on bepirovirsen (16%) than placebo (3%) during treatment in the pooled Phase 3 analysis.
What did the hepatitis B Phase 3 trials show?
In two replicate Phase 3 trials, adults with noncirrhotic chronic hepatitis B on stable nucleoside or nucleotide analogue therapy received weekly subcutaneous bepirovirsen 300 mg or placebo for 24 weeks.
Eligible patients discontinued NA therapy at 48 weeks. The primary outcome was functional cure at week 72, defined as sustained HBV DNA below LLOQ and HBsAg loss for at least 24 weeks. Full results appear in the NEJM Phase 3 report.
How do B-Well 1 and B-Well 2 compare on functional cure?
GSK said both pivotal trials met the primary endpoint with a clinically meaningful functional cure rate versus standard of care alone.
- B-Well 1: 127 of 650 patients (20%) on bepirovirsen vs none of 328 on placebo
- B-Well 2: 106 of 570 patients (19%) vs none of 286 on placebo
- Enrollment spanned more than 1,800 patients across 29 countries
- Greater effect was highlighted in patients with baseline HBsAg ≤1000 IU/ml
Company detail is in the GSK B-Well press release.
What is bepirovirsen and how is Ionis involved?
Bepirovirsen is an investigational antisense oligonucleotide designed to target hepatitis B viral RNA, suppress HBsAg, and support immune control after a finite course.
GSK licensed the asset from Ionis and holds development and commercialization responsibility. FDA Fast Track for chronic hepatitis B was supported by earlier B-Clear and B-Sure data, per GSK Fast Track announcement.
Which trial registries lock the protocol facts?
Public registry records identify B-Well 1 as NCT05630807 and B-Well 2 as NCT05630820 on ClinicalTrials.gov.
Baseline inclusion in the published Phase 3 analysis required HBsAg more than 100 to 3000 IU per milliliter while patients remained on NA therapy.
What safety signals should teams track?
Pooled week-72 reporting showed adverse events in 91% of bepirovirsen-treated patients versus 73% on placebo, and serious adverse events in 7% versus 4%.
During treatment, grade 3 or higher events occurred in 16% versus 3%, with alanine aminotransferase increases the most common grade 3 event on bepirovirsen (6%).
What remains unproven for hepatitis B functional cure claims?
Functional cure here is a lab-defined endpoint after finite therapy, not a guarantee of lifelong immunity or universal applicability across cirrhotic or higher-antigen populations.
Regulatory submissions, label language, and confirmatory durability beyond the reported week-72 window are not established in the cited Phase 3 publications alone.
How should hepatitis B portfolio teams act on B-Well?
Portfolio teams should update HBV competitive maps with finite antisense therapy as a real Phase 3 option, not only as a Phase 2 story.
Model scenarios for patients with baseline HBsAg at or below 1000 IU/ml separately from the broader cohort, because ranked endpoints highlighted a larger effect there.
Keep NA stop rules and rescue-therapy definitions explicit in any partner diligence memo so commercial claims do not outrun the week-72 functional-cure definition used in NEJM.
Ask CMC and device partners how weekly subcutaneous supply would scale if regulators later accept the B-Well package, while noting that approval is not yet granted in the cited materials.
Track both NCT05630807 and NCT05630820 registry updates for protocol amendments, primary-completion changes, and posted results tables.
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Frequently Asked Questions
What hepatitis B drug data did GSK and Ionis report?
Phase 3 B-Well 1 and B-Well 2 showed bepirovirsen plus nucleoside analogue therapy produced higher functional cure rates at week 72 than placebo, with NEJM reporting about 19–20% versus 0%.
What is a functional cure in these hepatitis B trials?
Functional cure was defined as HBsAg loss and HBV DNA below the lower limit of quantification for at least 24 weeks after finite treatment, including after planned NA discontinuation.
Is bepirovirsen FDA-approved for chronic hepatitis B?
No. The cited materials describe investigational Phase 3 results and prior FDA Fast Track designation; they do not constitute a marketing approval for chronic hepatitis B.
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