Vir's chronic hepatitis delta combo hits all endpoints in pivotal Phase 3 trial

What's the deal? Vir Biotechnology reported positive topline results from ECLIPSE 1, its pivotal Phase 3 trial of the combination of elebsiran and tobevibart in chronic hepatitis delta (CHD), the most severe form of chronic viral hepatitis (announced 9 November 2026). All study endpoints were met: 44% of treated patients achieved the primary endpoint — undetectable virus plus normal liver enzyme levels at Week 48 — versus 0% in the delayed-treatment group (p<0.0001). 79% of patients reached undetectable virus (again 0% in the control arm), and 100% achieved a virologic response (undetectable virus or a substantial reduction). The regimen was generally well tolerated, with no treatment discontinuations.

Elebsiran is an investigational RNA-based drug (a small interfering RNA licensed from Alnylam Pharmaceuticals) that silences the hepatitis B virus genes that the delta virus needs to replicate; tobevibart is an antibody that blocks the viruses from entering liver cells. The pair is given as monthly injections designed to attack the virus at several points at once. Data from the ECLIPSE programme will support a US FDA filing planned for mid-2027. Vir also presented expanded Phase 2 SOLSTICE data at AASLD 2026: 100% (28/28) of patients completing 96 weeks of combination therapy reached undetectable virus, and in an exploratory analysis all 10 patients who stopped treatment after sustained viral suppression remained virus-free after 12–48 weeks of follow-up.

Why it matters: Hepatitis delta has no broadly effective approved treatment and rapidly progresses to cirrhosis and liver cancer. These are the first pivotal Phase 3 data for a combination designed to clear the virus rather than merely suppress it, and the early “finite treatment” signal hints at the possibility of a cure with a defined course of therapy.

Read more: Vir Biotechnology, 9 November 2026 · BioSpace, 9 November 2026