All spots filled in trial testing Vir’s combo treatment for hepatitis D
Results from global study of tobevibart plus elebsiran expected in early 2027
Enrollment is now complete for Vir Biotechnology’s global ECLIPSE 1 trial, which is testing the combination treatment of tobevibart and elebsiran in people with chronic hepatitis D — also called hepatitis delta.
The Phase 3 trial had worked to enroll 120 people with hepatitis D at 39 study sites worldwide. It is evaluating the safety and effectiveness of using the two therapies together as a treatment.
“Reaching full enrollment in our ECLIPSE 1 Phase 3 clinical trial marks an essential milestone as we work [toward] submission of the combination of tobevibart and elebsiran for the treatment of chronic hepatitis delta to global regulatory agencies,” Marianne De Backer, PhD, CEO of Vir, said in a company press release announcing the milestone.
With all participants enrolled, the global ECLIPSE 1 trial (NCT06903338) is expected to complete clinical visits in the final months of 2026, with top-line results expected in early 2027.
In the study, adults with chronic hepatitis D are being randomly assigned to either receive tobevibart plus elebsiran or to have treatment deferred for several years. The study’s main goals are to assess the treatment combo’s safety and ability to reduce levels of viral genetic material below the limit of quantification while normalizing liver damage markers.
Vir said that the trial wrapped up enrollment relatively quickly — an indicator of the high unmet need for hepatitis D treatments.
“The strong interest and participation in ECLIPSE 1 reflect the urgent need for innovative solutions in chronic hepatitis delta, as well as the encouraging potential of the combination of tobevibart and elebsiran,” said Mark Eisner, MD, chief medical officer of Vir.
Hepatitis D virus only infects people who already have HBV
Hepatitis refers to liver inflammation. Most cases of hepatitis are caused by viral infections, the most common being hepatitis B, known as HBV. The hepatitis D virus, or HDV, is a less common virus that can only infect people who are already infected with HBV.
Compared with HBV only, coinfection with HBV and HDV is linked with substantially worse outcomes, including a much higher risk of liver cancer.
Tobevibart, also known as VIR-3434, is designed to block viral particles of HBV and HDV from getting into cells in the body. Meanwhile, elebsiran (VIR-2218) is expected to work to decrease levels of HBV proteins that HDV needs to infect liver cells. Both therapies are given by under-the-skin (subcutaneous) injection.
Previously reported data from a Phase 2 clinical trial called SOLSTICE (NCT05461170) indicated that the treatments together reduced HDV levels in all participants who received them.
Vir is now running three clinical trials as part of its ECLIPSE program to test tobevibart and elebsiran in chronic hepatitis D. While ECLIPSE 1 is comparing the experimental combo against delayed treatment, the other two studies are testing the treatments together against bulevirtide, which is conditionally approved in the European Union as a treatment for chronic hepatitis D. Bulevirtide is sold in Europe under the brand name Hepcludex, but it is not authorized for use in the U.S. and many other countries.
2 other ECLIPSE trials also testing hepatitis D combo treatment
The ECLIPSE 2 trial (NCT07128550), also a Phase 3 study, is enrolling people ages 18 to 70 who have chronic hepatitis D and persistent high levels of viral genetic material despite being on bulevirtide for at least six months.
Participants will be randomly assigned to either continue on bulevirtide or to switch to tobevibart plus elebsiran for about six months, with the main goal of assessing changes in viral levels. After the initial six months, all participants will receive the combination therapy for several years of follow-up.
We are dedicated to advancing our registrational program with utmost urgency to deliver a much-needed new treatment option for people living with hepatitis delta.
The ECLIPSE 2 study is currently recruiting participants at 20 sites in France, Germany, Romania, Spain, and the U.K. Assuming the results are positive, Vir is planning to use data from ECLIPSE 1 and ECLIPSE 2 as a basis to apply for approvals of the combination therapy.
“We are dedicated to advancing our registrational program with utmost urgency to deliver a much-needed new treatment option for people living with hepatitis delta,” De Backer said.
The third trial in the program, ECLIPSE 3 (NCT07142811), is a Phase 2 study that’s directly comparing tobevibart-elebsiran against bulevirtide in adults with chronic hepatitis D who have not previously received bulevirtide treatment. That study is recruiting participants at sites in the U.K., France, Germany, Belgium, Bulgaria, Moldova, the Netherlands, Romania, Spain, Ukraine, and Pakistan.
According to Vir, both ECLIPSE 2 and ECLIPSE 3 are enrolling well and at a rate in line with company expectations.
Eisner expressed appreciation to all involved in the clinical testing.
“We are proud of our continued progress across the entire ECLIPSE program, and grateful to the physicians and patients choosing to join our trials,” Eisner said.
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