Vir's elebsiran-tobevibart hits primary endpoint in Phase 3 hepatitis delta trial

Vir Biotechnology disclosed topline results from its pivotal Phase 3 ECLIPSE 1 trial in an 8-K dated November 8, 2026, with data presented in an oral session at the AASLD Liver Meeting in Denver that same day. The trial tested monthly subcutaneous elebsiran, an investigational small interfering RNA, and tobevibart, an investigational monoclonal antibody, in adults with chronic hepatitis delta.¹

ECLIPSE 1 enrolled a total of 124 patients, randomized 2:1, to receive monthly subcutaneous elebsiran and tobevibart or delayed treatment, with the delayed treatment group initiating therapy at Week 12.¹

The trial's primary endpoint was met, with a 44% response rate in patients receiving elebsiran and tobevibart achieving undetectable virus as defined by hepatitis delta virus RNA target not detected plus alanine aminotransferase normalization at Week 48, compared with 0% in the delayed treatment group at Week 12 (p<0.0001).¹ The key secondary endpoint also was met, with a 79% response rate in patients achieving undetectable virus at Week 48 versus 0% in the delayed treatment group.¹ Response was seen regardless of cirrhosis status, with HDV RNA TND achieved in 85% of cirrhotic patients (n=46) and 73% of non-cirrhotic patients (n=37).¹

On safety, there was one Grade 3 treatment-related adverse event, a neutrophil count decrease that resolved in 15 days, and no treatment interruptions or discontinuations.¹

Vir also reported expanded Week 96 data from the Phase 2 SOLSTICE study, where 100% (28/28) of patients who completed Week 96 of combination therapy reached undetectable viremia.¹ In an exploratory finite-treatment analysis, ten patients, seven of whom are cirrhotic, chose to discontinue treatment, and all 10 achieved SVR12.¹ Vir cautioned that this data represents an interim snapshot of the first 10 patients and may not be representative of the broader study population or longer follow-up.¹