Vir's Hepatitis Delta Combo Leaves Virus Undetectable in 79%

Vir Biotechnology said its two-drug regimen for chronic hepatitis delta met the main goal of a pivotal phase 3 trial. The San Francisco company released the ECLIPSE 1 results on Nov. 8, 2026. The data were presented at The Liver Meeting 2026 in Denver.

What happened

ECLIPSE 1 tested elebsiran and tobevibart, given monthly as two separate injections under the skin. The trial enrolled 124 patients and randomized them 2:1. According to HCPLive, 83 started treatment right away and 41 began it after a 12-week delay.

The main goal combined two measures: no detectable hepatitis D virus and a normal ALT, a liver enzyme. Vir said 44% of treated patients met it at week 48. None of the patients in the delayed group met it at week 12.

• Undetectable virus: 79% of treated patients at week 48, versus 0% in the delayed group, the key secondary goal.
• By liver status: 85% of patients with cirrhosis (46 people) and 73% without it (37 people) had undetectable virus.
• Normal ALT: 53% of treated patients, versus 5% in the delayed group.

On safety, Vir reported one grade 3 side effect tied to treatment, a drop in neutrophil count that resolved within 15 days. No patient paused or stopped treatment. Flu-like symptoms were the most common side effect, mostly after the first dose.

Why it matters

Hepatitis delta only infects people who already have hepatitis B. HCPLive, citing the World Health Organization, reported it affects nearly 5% of people with chronic hepatitis B, or an estimated 12 million people worldwide. Vir's release calls it the most severe form of chronic viral hepatitis.

Vir said approved treatments remain limited in the US and globally. HCPLive reported that the FDA granted accelerated approval to bulevirtide in May 2026, making it the first US treatment for the disease. Vir says ECLIPSE 1 is meant to support use in the US and other regions where bulevirtide use is limited.

There are limits to these results. The comparison group got delayed treatment, not another drug. HCPLive noted that comparing these numbers with bulevirtide trials should be done with caution.

What it means for people in the industry

Two more phase 3 trials come next. ECLIPSE 2 tests a switch for patients whose virus is not suppressed on bulevirtide. ECLIPSE 3 compares the regimen head to head with bulevirtide. Vir expects data from both in the first quarter of 2027.

Vir plans to send a full filing package to the FDA in mid-2027. The regimen already holds FDA Breakthrough Therapy and Fast Track designations. In Europe, Australia and New Zealand, Norgine holds an exclusive licence signed in December 2025.

For people in regulatory, medical affairs and manufacturing, the 2027 readouts and filing are the dates to watch. Vir has not announced any hiring tied to the results.

See open pharma jobs in the US and Canada

Sources

• Vir Biotechnology Announces Primary Endpoint Met in Pivotal Phase 3 ECLIPSE 1 Trial for Elebsiran and Tobevibart in Chronic Hepatitis Delta, Vir Biotechnology (Business Wire release)
• Elebsiran Plus Tobevibart Suppresses HDV RNA in Phase 3 ECLIPSE 1 Trial, HCPLive