Vir Hepatitis Delta Trial Hits Primary Endpoint

Vir Biotechnology's phase 3 Eclipse 1 trial in chronic hepatitis delta met its primary goal, and its shares rose in premarket trading.

Updated on Nov. 9, 2026 in Biotech

Vir Hepatitis Delta Trial Hits Primary Endpoint

Vir Biotechnology said its phase 3 Eclipse 1 trial in chronic hepatitis delta hit its primary endpoint. Shares rose 17% to $14.25 in premarket trading Monday after closing at $21.21 on Friday.

Why it matters

Chronic hepatitis delta is a serious viral liver disease, and the trial's results add data to a field where Gilead's Hepcludex received FDA approval in May. The readout also follows Mirum Pharmaceuticals' phase 3 win for brelovitug in September.

The phase 3 result compares 44% of immediate-treatment patients achieving undetectable HDV RNA and normal ALT at Week 48 against a delayed-treatment arm in which no patients met the primary endpoint at Week 12. Results beyond these timepoints and the outcomes of two additional pivotal trials remain unreported.

The players

Vir Biotechnology

A San Francisco-headquartered biotechnology company developing treatments for chronic viral diseases, including hepatitis delta.

Gilead Sciences

A major American biopharmaceutical company whose Hepcludex received FDA approval for chronic hepatitis delta in May, making it the existing treatment in this space.

Mirum Pharmaceuticals

A biopharmaceutical company that reported a phase 3 win for its investigational drug brelovitug in chronic hepatitis delta in September.

The details

The Eclipse 1 trial enrolled 124 patients and tested monthly subcutaneous elebsiran and tobevibart in adults with chronic hepatitis delta. Two-thirds started the combination immediately, while one-third began treatment at Week 12; Vir also reported phase 2 data in which all 28 patients who completed 96 weeks of combination therapy had undetectable virus.

- May: Gilead won FDA approval for Hepcludex in chronic hepatitis delta.
- September: Mirum Pharmaceuticals reported a phase 3 win for brelovitug.
- Friday: Vir shares closed at $21.21 before the readout.
- Monday: Vir shares rose 17% to $14.25 in premarket trading.
- Mid-2027: Vir plans to seek U.S. approval using data from all three pivotal trials.

The Tech Race

Vir's phase 3 result places it alongside Gilead's approved Hepcludex, which won FDA approval for chronic hepatitis delta in May, and Mirum's brelovitug, which reported a phase 3 win in September. The three pivotal programs now compete to define treatment options for a disease with few established therapies.

For patients with chronic hepatitis delta, the trial suggests that monthly subcutaneous treatment may be a future option, though it is not yet approved. Patients and clinicians should follow regulatory decisions, which are not expected before mid-2027.

The takeaway

The Eclipse 1 data add to a growing set of options for chronic hepatitis delta, and the forthcoming pivotal results will determine how the field develops.

What happens next

Vir plans to seek U.S. approval in mid-2027 using data from all three pivotal trials, and data from two other pivotal trials are expected in the first quarter of 2027.