The primary objective of the study is to evaluate the effectiveness and safety of brelovitug (BJT-778) as a long-term treatment in participants with chronic hepatitis delta virus (HDV) infection, the virus responsible for chronic hepatitis D (CHD).

BJT-778 is an investigational study drug, which  means that it is not an approved treatment for HDV infection by the U.S. Food and Drug Administration (FDA)    

Eligible participants are randomly assigned to one of 3 different groups. Group 1 will receive BJT-778 300 mg once per week for 96 weeks, Group 2 will receive BJT-778 900 mg once every 2 weeks for 4 weeks, then every 4 weeks for 92 weeks, and Group 3 will delay treatment for 24 weeks, after which BJT-778 300mg will be self-administered once a week for 96 weeks.

If assigned to Group 1 or 2, participants will be in the study for 105 weeks. If assigned to Group 3, participants will be in the study for 129 weeks.

The main study procedures include study drug injection (at the intervals designated by the participant’s group) and liver scans (FibroScan and ultrasound).