Vir Biotechnology has announced positive topline results from the pivotal Phase 3 ECLIPSE 1 trial evaluating monthly subcutaneous administration of elebsiran and tobevibart in adults with chronic hepatitis delta. Results were presented at the AASLD Liver Meeting 2026 in Denver.
ECLIPSE 1 enrolled 124 patients, randomized 2:1 to receive elebsiran and tobevibart or delayed treatment, with the delayed treatment group initiating therapy at Week 12.
The trial met its primary endpoint, with 44% of patients receiving elebsiran and tobevibart achieving undetectable virus, defined as HDV RNA target not detected, plus ALT normalization at Week 48, compared with 0% in the delayed treatment group at Week 12 (p<0.0001). The key secondary endpoint was also met, with 79% achieving undetectable virus at Week 48 versus 0% in the delayed treatment group. Undetectable virus was observed regardless of cirrhosis status, with HDV RNA TND achieved in 85% of cirrhotic patients and 73% of non-cirrhotic patients. Virologic response was achieved in 100% of treated patients, ALT normalization in 53%, and 95% had HBsAg below 10 IU/mL on an exploratory basis.
The regimen was well-tolerated. There was one Grade 3 treatment-related adverse event, a neutrophil count decrease that resolved in 15 days, and no treatment interruptions or discontinuations. The most common treatment-related adverse event was flu-like symptoms, predominantly occurring at first dose.
The regimen is also being evaluated in ECLIPSE 2 and ECLIPSE 3, with data expected in the first quarter of 2027. Data from all three trials will support a U.S. FDA submission planned for mid-2027. The regimen holds FDA Breakthrough Therapy and Fast Track designations and EMA PRIME and orphan drug designations.
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