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News|Articles|November 9, 2026

Elebsiran and Tobevibart Meet Primary End Point in Hepatitis Delta Study

The combination of elebsiran and tobevibart (Vir Biotechnology) met the primary end point in the pivotal phase 3 ECLIPSE 1 trial in adults with chronic hepatitis delta, according to a company announcement.1 At week 48, 44% of patients in the treatment arm achieved undetectable hepatitis delta virus (HDV) RNA with alanine aminotransferase (ALT) normalization, compared with 0% in the delayed-treatment arm at week 12 (P < .0001).1 Vir presented the topline results in an oral session at The Liver Meeting 2026 of the American Association for the Study of Liver Diseases in Denver, Colorado.1

The ECLIPSE 1 results come as Vir prepares a global regulatory package for the regimen, which holds FDA Breakthrough Therapy and Fast Track designations.1 The company announced completion of enrollment in the trial in November 2025.2 Norgine holds an exclusive license for Europe, Australia, and New Zealand under a December 2025 agreement.1

ECLIPSE 1 Design and Primary End Point Results for Elebsiran and Tobevibart

ECLIPSE 1 enrolled 124 adults with chronic hepatitis delta and randomized them 2:1 to monthly subcutaneous elebsiran plus tobevibart or to delayed treatment, which began at week 12.1 The treatment arm included 83 patients and the delayed-treatment arm included 41.1 The primary end point was undetectable HDV RNA (target not detected) with ALT normalization at week 48 in the treatment arm vs the delayed-treatment arm at week 12.1

The primary end point occurred in 44% of patients in the treatment arm vs 0% in the delayed-treatment arm (P < .0001).1 Undetectable HDV RNA alone, a key secondary end point, occurred in 79% vs 0% (P < .0001), and ALT normalization occurred in 53% vs 5%.1 Among patients with cirrhosis (n = 46), 85% achieved undetectable HDV RNA, as did 73% of patients without cirrhosis (n = 37).1

In an exploratory analysis, 95% of patients in the treatment arm reached hepatitis B surface antigen levels below 10 IU/mL vs 0% in the delayed-treatment arm.1 The results were announced alongside expanded phase 2 SOLSTICE data for the regimen in chronic hepatitis delta, which Vir described as showing deep and sustained viral suppression.3

Frequently Asked Questions

What did the ECLIPSE 1 trial show?

Monthly elebsiran plus tobevibart produced undetectable HDV RNA with ALT normalization in 44% of patients at week 48 vs 0% with delayed treatment at week 12 (P < .0001).

What safety findings did ECLIPSE 1 report?

There was 1 grade 3 treatment-related adverse event, a neutrophil count decrease, which resolved in 15 days. No patients had treatment interruptions or discontinuations.

What is the regulatory timeline for elebsiran and tobevibart?

Vir expects ECLIPSE 2 and ECLIPSE 3 data in the first quarter of 2027 and plans a global regulatory package for the FDA in mid-2027.

Safety, Tolerability, and Regulatory Timeline for Elebsiran Plus Tobevibart

Investigators reported 1 grade 3 treatment-related adverse event, a decrease in neutrophil count, which resolved in 15 days.1 No patients had treatment interruptions or discontinuations in the trial.1 Most treatment-related adverse events were mild to moderate and transient.1

Flu-like symptoms were the most common treatment-related adverse event. They occurred mostly after the first dose and mostly resolved within 24 to 48 hours.1

ECLIPSE 1 is 1 of 3 phase 3 trials in the elebsiran and tobevibart program. Vir expects data from ECLIPSE 2 and ECLIPSE 3 in the first quarter of 2027.1 The company plans to submit a comprehensive global regulatory package to the FDA in mid-2027.1

The release also lists EMA PRIME and orphan drug designations for the regimen.1 Vir described the 2 agents as having complementary mechanisms of action.1

“Our ambition in hepatitis delta has always been to fundamentally change what patients can expect from treatment,” Marianne De Backer, president and chief executive officer of Vir Biotechnology, said in a statement.1

Vir has positioned the regimen as a once-monthly subcutaneous option for chronic hepatitis delta, with the first regulatory filing planned after the remaining phase 3 data read out.1

References
  1. Vir Biotechnology announces primary endpoint met in pivotal phase 3 ECLIPSE 1 trial for elebsiran and tobevibart in chronic hepatitis delta. News release. Vir Biotechnology. November 9, 2026. Accessed November 9, 2026. https://www.biospace.com/press-releases/vir-biotechnology-announces-primary-endpoint-met-in-pivotal-phase-3-eclipse-1-trial-for-elebsiran-and-tobevibart-in-chronic-hepatitis-delta
  2. Vir Biotechnology announces completion of enrollment in ECLIPSE 1 phase 3 trial for chronic hepatitis delta. News release. Vir Biotechnology. November 3, 2025. Accessed November 9, 2026. https://www.businesswire.com/news/home/20251103530329/en/Vir-Biotechnology-Announces-Completion-of-Enrollment-in-ECLIPSE-1-Phase-3-Trial-for-Chronic-Hepatitis-Delta
  3. Vir Biotechnology announces expanded phase 2 SOLSTICE data for elebsiran and tobevibart in chronic hepatitis delta, showing deep and sustained viral suppression, and exploratory finite treatment data. News release. Vir Biotechnology. November 2026. Accessed November 9, 2026. https://www.biospace.com/press-releases/vir-biotechnology-announces-expanded-phase-2-solstice-data-for-elebsiran-and-tobevibart-in-chronic-hepatitis-delta-showing-deep-and-sustained-viral-suppression-and-exploratory-finite-treatment-data

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