Vir's Hepatitis Delta Combo Hits Every Phase 3 Target: 79% Undetectable

Vir Biotechnology (Nasdaq: VIR) said Sunday that its monthly hepatitis delta combination of elebsiran and tobevibart met every endpoint in the pivotal Phase 3 ECLIPSE 1 trial — 79% of treated patients had undetectable virus at Week 48, against 0% in the delayed-treatment group. The results, presented at the AASLD Liver Meeting in Denver, set up a conference call Monday morning and a planned U.S. FDA filing in mid-2027.

What happened

Vir announced positive topline results from ECLIPSE 1, a Phase 3 trial in adults with chronic hepatitis delta (CHD), the most severe form of chronic viral hepatitis. A total of 124 patients were randomized 2:1 to receive monthly subcutaneous injections of elebsiran plus tobevibart, or delayed treatment, with the control group starting therapy at Week 12. The trial included patients with advanced disease.

The primary endpoint was met with a 44% response rate — patients achieving both undetectable virus, defined as hepatitis delta virus RNA target not detected, and normalization of the liver enzyme ALT at Week 48 — compared with 0% in the delayed-treatment group at Week 12 (p<0.0001).

The key numbers

• 79% of treated patients reached undetectable virus at Week 48, the key secondary endpoint, versus 0% in the delayed group.
• 100% achieved a virologic response at Week 24.
• 85% of patients with cirrhosis and 73% without cirrhosis reached undetectable virus.
• 53% achieved ALT normalization, versus 5% in the delayed group.
• Safety: one Grade 3 treatment-related adverse event (a neutrophil count decrease that resolved in 15 days), no treatment interruptions or discontinuations, and all patients completed 48 weeks of treatment. The most common side effect was flu-like symptoms, mostly at the first dose.

Why it is blowing up

Chronic hepatitis delta only occurs in people who also have hepatitis B, and it progresses faster than other forms of viral hepatitis — toward cirrhosis, liver failure and liver cancer. It was recently classified as carcinogenic by the International Agency for Research on Cancer, and approved treatment options in the U.S. and globally remain limited. A monthly regimen that drives the virus to undetectable levels in most patients, including most patients who already have cirrhosis, addresses a disease with few alternatives.

The second data set Vir released Sunday added to the attention. In the Phase 2 SOLSTICE trial, all 28 patients (28/28) who completed 96 weeks of combination therapy had undetectable virus. In an exploratory finite-treatment analysis, the first 10 patients who stopped therapy after sustained suppression all remained virus-free 12 weeks later, seven maintained that response through 24 weeks, and one reached 48 weeks. Vir and outside coverage both caution that this early, small-sample result does not establish a lasting cure — but it is the part of the release drawing the most discussion, because it raises the possibility that some patients might one day stop treatment altogether.

The regimen has already received FDA Breakthrough Therapy and Fast Track designations, and Priority Medicines (PRIME) and orphan drug designations from the European Medicines Agency — statuses that can speed development and review, without guaranteeing approval.

How the two drugs work

Elebsiran is a small interfering RNA, licensed from Alnylam Pharmaceuticals, designed to limit production of the hepatitis B surface antigen that hepatitis delta needs to replicate. Tobevibart is a monoclonal antibody designed to block both viruses from entering liver cells. The two are given as separate monthly injections under the skin, at home or by a healthcare provider.

What's next

Vir hosts a conference call on Monday, November 9 at 8:30 a.m. ET to discuss the ECLIPSE 1 results and the expanded SOLSTICE data — the first chance for analysts to question management, and the first trading session in which the stock can react. Data from the two other pivotal trials, ECLIPSE 2 and ECLIPSE 3, are expected in the first quarter of 2027. Together, all three trials will support a comprehensive regulatory filing package planned for U.S. FDA submission in mid-2027.

In December 2025, Vir licensed the combination to Norgine for commercialization in Europe, Australia and New Zealand, subject to marketing authorizations. It remains investigational and is not approved anywhere.

Sources: Vir Biotechnology press release via ADVFN (Business Wire); Seeking Alpha via TradingView; Quantisnow; Vir SOLSTICE Phase 2 release via Stockhouse. This post reports the trial results and the company's stated plans; it is not financial or medical advice.

Frequently Asked Questions

What did Vir Biotechnology announce on Sunday?

Vir said its elebsiran and tobevibart combination met all endpoints in the Phase 3 ECLIPSE 1 trial in chronic hepatitis delta, with 79% of treated patients reaching undetectable virus at Week 48 versus 0% in the delayed-treatment group.

When could the treatment reach patients?

Not before regulatory review: Vir plans ECLIPSE 2 and ECLIPSE 3 data in the first quarter of 2027 and a U.S. FDA submission in mid-2027, and the combination is not approved anywhere yet.

Did the data show a cure for hepatitis delta?

No. In a small exploratory group, all 10 patients who stopped treatment stayed virus-free 12 weeks later, but Vir and independent coverage caution that the sample and follow-up are too limited to establish a lasting cure.

What happens next for Vir stock watchers?

Vir discusses the results on a conference call Monday, November 9 at 8:30 a.m. ET, ahead of the first regular trading session since the Sunday announcement.