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Trial met all Phase 3 endpoints and regimen is well-tolerated with all patients completing 48 weeks of treatment
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100% of patients achieved virologic response at Week 24 with 79% of patients reaching undetectable virus (as defined by HDV RNA TND) at Week 48
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Comprehensive regulatory filing package planned for U.S. FDA submission mid-2027
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Conference call to discuss topline ECLIPSE 1 results and expanded SOLSTICE Phase 2 data scheduled for November 9, 2026, at 8:30 a.m. ET / 5:30 a.m. PT
11/08/2026--SAN FRANCISCO--(BUSINESS WIRE)-- Vir Biotechnology, Inc. (Nasdaq: VIR), today 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 (CHD). Topline results were presented in an oral session at the American Association for the Study of Liver Diseases (AASLD) The Liver Meeting® 2026, in Denver, Colorado.
“For people living with CHD, the goal is not simply to reduce the amount of virus, but to drive it to levels where it is no longer detectable since ongoing HDV replication drives liver disease progression,” said Nancy Reau, Associate Director of Solid Organ Transplantation and Section Chief of Hepatology at Rush University Medical Center. “The high number of participants who achieved undetectable virus and normalized ALT levels in ECLIPSE 1 shows that the combination regimen of elebsiran and tobevibart could offer a meaningful new treatment option for people living with this serious, progressive disease.”
ECLIPSE 1 Week 48 Topline Data
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. The trial enrolled a broad and diverse CHD population across multiple countries and included patients with advanced disease.
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 (HDV RNA TND) plus alanine aminotransferase (ALT) normalization at Week 48, compared with 0% in the delayed treatment group at Week 12 (p<0.0001).
The trial also met its key secondary endpoint, with a 79% response rate in patients achieving undetectable virus at Week 48 versus 0% in the delayed treatment group. Undetectable virus was observed across patients regardless of cirrhosis status, with HDV RNA TND achieved in 85% of cirrhotic patients (n=46) and 73% of non-cirrhotic patients (n=37). Topline data are summarized in the below table, “Phase 3 Efficacy Endpoints.”
The regimen was well-tolerated with a favorable safety profile. There was one Grade 3 treatment-related adverse event (TRAE; neutrophil count decrease, which resolved in 15 days) and no treatment interruptions or discontinuations. Most TRAEs were mild to moderate and transient. The most common TRAE was flu-like symptoms, which predominantly occurred at first dose with the majority resolved within 24 to 48 hours.
Phase 3 Efficacy Endpoints
|
Endpoint |
Week 48 |
Week 12 |
|
Elebsiran + Tobevibart Q4W (N = 83) |
Delayed Treatment Arm (N = 41) |
|
|
Primary Endpoint Undetectable virus (HDV RNA TND) + ALT normalization
P-value |
44%
<0.0001 |
0%
<0.0001 |
|
Key Secondary Endpoint Undetectable virus (HDV RNA TND)
P-value |
79%
<0.0001 |
0%
<0.0001 |
|
Virologic Response HDV RNA TND or HDV RNA ≥2 log10 reduction |
100% |
0% |
|
ALT Normalization |
53% |
5% |
|
HBV Surface Antigen (HBsAg) <10 IU/mL (Exploratory) |
95% |
0% |
“Our ambition in hepatitis delta has always been to fundamentally change what patients can expect from treatment. These compelling ECLIPSE 1 results deliver on the potential for elebsiran’s and tobevibart’s complementary mechanisms to drive the virus to undetectable levels, potentially lowering the risk of progression to cirrhosis, liver cancer and liver-related mortality,” said Marianne De Backer, President and Chief Executive Officer of Vir Biotechnology. “We believe the robust viral suppression combined with the flexibility of monthly at-home or healthcare provider administration has the potential to position elebsiran and tobevibart as the best-in-disease treatment for hepatitis delta.”
The elebsiran and tobevibart regimen is also being evaluated in the ECLIPSE 2 and ECLIPSE 3 pivotal trials with data expected in the first quarter of 2027. Data from all three trials will support a comprehensive global regulatory filing package planned for U.S. FDA submission in mid-2027.
The significant unmet need in CHD and the potential for the combination of elebsiran and tobevibart to provide a differentiated treatment option has been recognized by the U.S. Food and Drug Administration (FDA) with Breakthrough Therapy and Fast Track designations, and by the European Medicines Agency (EMA) with Priority Medicines (PRIME) and orphan drug designations.
In December 2025, Vir Biotechnology entered into an exclusive licensing agreement with Norgine, under which Norgine will be responsible for the commercialization of elebsiran and tobevibart in Europe, Australia and New Zealand, subject to receipt of the necessary marketing authorizations.
About the ECLIPSE Registrational Program
ECLIPSE is a registrational program to evaluate the safety and efficacy of elebsiran in combination with tobevibart in patients with chronic hepatitis delta (CHD). ECLIPSE includes three randomized, controlled trials designed to evaluate the combination therapy in comparison to delayed treatment or bulevirtide. ECLIPSE 1 (NCT06903338) is a Phase 3 trial evaluating the safety and efficacy of elebsiran in combination with tobevibart compared to delayed treatment in the U.S. or other regions where bulevirtide use is limited. ECLIPSE 2 (NCT07128550) is a Phase 3 trial evaluating the efficacy and safety of switching to elebsiran and tobevibart in people with CHD who have not achieved viral suppression with bulevirtide therapy. ECLIPSE 1 and 2 are designed to provide the registrational efficacy and safety data needed for potential submission to global regulatory agencies. ECLIPSE 3 (NCT07142811) is a pivotal head-to-head trial evaluating combination elebsiran and tobevibart compared with bulevirtide in bulevirtide-naïve patients, and it is designed to provide important supportive data to help establish access and reimbursement in key markets.
About Elebsiran and Tobevibart
Elebsiran and tobevibart are investigational agents being evaluated as a novel combination regimen administered monthly as two separate sequential subcutaneous injections for the treatment of chronic hepatitis delta (CHD). The combination is designed to disrupt the hepatitis delta virus (HDV) life cycle at multiple points by addressing both viral entry and the sustained presence of hepatitis B surface antigen (HBsAg) that enables ongoing HDV replication.
Elebsiran is an investigational hepatitis B virus-targeting small interfering ribonucleic acid (siRNA) licensed from Alnylam Pharmaceuticals, Inc. It is designed to degrade hepatitis B virus RNA transcripts and limit the production of HBsAg.
Tobevibart is an investigational broadly neutralizing monoclonal antibody (mAb) targeting HBsAg. It is designed to inhibit the entry of hepatitis B and hepatitis delta viruses into hepatocytes and to reduce the level of circulating viral and subviral particles in the blood. Tobevibart was identified using Vir Biotechnology’s proprietary mAb discovery platform. The Fc domain has been engineered to increase immune engagement and clearance of HBsAg immune complexes and incorporates Xencor’s Xtend™ technology to extend half-life.
About Chronic Hepatitis Delta (CHD)
CHD is the most severe form of chronic viral hepatitis1 and was recently classified as carcinogenic by the International Agency for Research on Cancer.2 People living with the disease rapidly progress to cirrhosis, liver failure3 and liver-related death.1 Because ongoing hepatitis delta virus (HDV) replication drives disease progression, achieving undetectable virus, as defined by HDV RNA TND (target not detected), is considered an important virologic marker associated with improved clinical outcomes in CHD.4 Individuals with CHD who have detectable HDV RNA are at a higher risk of experiencing any liver-related event, including developing compensated and decompensated cirrhosis, hepatocellular carcinoma, liver transplantation and mortality, compared to patients with undetectable HDV RNA.4 There are currently limited approved treatments in the U.S. and globally.
About Vir Biotechnology, Inc.
Vir Biotechnology, Inc. is a clinical-stage biopharmaceutical company focused on powering the immune system to transform lives by discovering and developing medicines for serious infectious diseases and cancer. Its clinical-stage portfolio includes programs for chronic hepatitis delta and multiple PRO-XTEN® dual-masked T-cell engagers across validated targets in solid tumor indications. Vir Biotechnology also has a preclinical portfolio of programs across a range of oncologic malignancies. Vir Biotechnology routinely posts information that may be important to investors on its website.