A Study to Evaluate Tobevibart + Elebsiran in Chronic HDV Infection

The purpose of this study is to evaluate the safety and effectiveness of Tobevibart (VIR-3434) and Elebsiran (VIR-2218) in treating chronic hepatitis delta virus (HDV) infection. Tobevibart is an antibody, a type of protein that helps the immune system fight infections. Elebsiran is a small RNA molecule designed to reduce the amount of hepatitis D virus (HDV) in the body. These drugs are investigational, meaning that they are not approved by the U.S. Food and Drug Administration (FDA) and must be tested to see if they are safe and effective treatments for the disease or condition being studied.

If you agree to participate in this study, your participation may last up to 283 weeks (about 5 and a half years) depending on the study arm to which you are assigned. You will be required to attend up to 60 study visits, with injections administered every four weeks throughout the treatment period.

During these visits, you will receive subcutaneous (under the skin) injections of Tobevibart and Elebsiran, have blood and urine tests, imaging scans, electrocardiograms (ECGs, which measure the electrical activity of the heart), and complete questionnaires about your health. Genetic testing and biospecimen collection will also occur as part of the study.

In order to participate you must meet the following criteria:

• Are male or female, 18 to 70 years of age at screening.
• Have had chronic HDV infection for >/= 6 months.
• Have been on NRTI therapy against HBV for at least 12 weeks prior to day 1 or have HBV DNA < 20 IU/ml at screening, currently on locally approved NRTI therapy.
• Have serum ALT > ULN and < 5x ULN.
• Have non-cirrhotic or compensated cirrhotic liver disease at screening.

You will be excluded from the study if any of the following criteria apply to you:

• Have any clinically significant chronic or acute medical or psychiatric condition that makes the participant unsuitable for participation.
• Have a history of significant liver disease from non-HBV or non-HDV etiology.
• Have a history of allergic reactions, hypersensitivity, or intolerance to study drug, its metabolites, or excipients.
• Have a history of anaphylaxis.
• Have a history of immune complex disease.
• Have a history of autoimmune disorder.
• Have a history or evidence of alcohol or drug abuse within 6 months before screening or a positive drug screen at screening unless it can be explained by a prescribed medication.

This is a partial list of eligibility requirements. To inquire about your eligibility, please call the contact number provided. If you wish to inquire via email, please include the title of the study in your message.