This is a Phase 2b/3, randomized, open-label, multicenter trial evaluating the efficacy and safety of switching from bulevirtide to brelovitug for the treatment of chronic hepatitis Delta infection (CHD).

This is a Phase 2b/3, open-label, multicenter study evaluating the efficacy and safety of switching participants on bulevirtide to brelovitug for the treatment of chronic hepatitis delta (CHD).

Inclusion Criteria:

1. Willing and able to provide written informed consent.
2. Male or female, ≥18 years of age at Screening.
3. Taking or willing to take TDF, TAF, or ETV at baseline, and willing to remain on stable treatment for the duration of the study.
4. Currently taking bulevirtide treatment for CHD for ≥6 months at the time of Screening.
5. HDV RNA ≥100 IU/mL at Screening.

Exclusion Criteria:

1. Evidence of decompensated liver disease (e.g., CTP Class B or C, history of hepatic encephalopathy, clinically significant ascites, or variceal bleeding).
2. Known history of immune-complex disease.
3. Active or clinically significant co-infection with hepatitis C virus (HCV) or human immunodeficiency virus (HIV).
4. Evidence of other significant liver diseases (e.g., autoimmune hepatitis, primary biliary cholangitis, primary sclerosing cholangitis).
5. History of hepatocellular carcinoma (HCC) or evidence of HCC on screening imaging.