A Study to Evaluate Tobevibart + Elebsiran in Chronic HDV Infection

Inclusion Criteria:

1. Male or female ages 18 to 70 years at screening

2. Chronic HDV infection for >/= 6 months

3. 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

4. Serum ALT > ULN and < 5x ULN

5. Non-cirrhotic or Compensated Cirrhotic Liver Disease at screening

Exclusion Criteria:

1. Any clinically significant chronic or acute medical or psychiatric condition thatmakes the participant unsuitable for participation.

2. History of significant liver disease from non-HBV or non-HDV etiology

3. History of allergic reactions, hypersensitivity, or intolerance to study drug, itsmetabolites, or excipients.

4. History of anaphylaxis

5. History of immune complex disease

6. History of autoimmune disorder

7. History or evidence of alcohol or drug abuse within 6 months before screening or apositive drug screen at screening unless it can be explained by a prescribedmedication