SOLSTICE: Combination Therapy for the Treatment of Chronic Hepatitis D Infection.

Inclusion Criteria: * Male or female ages 18 to \< 70 years at screening * Chronic HDV infection for \>/= 6 months * On NRTI therapy for at least 12 weeks prior to day 1 * ALT\>ULN and \< 5x ULN * Non-cirrhotic and CPT-A cirrhotic Exclusion Criteria: * Any clinically significant chronic or acute medical or psychiatric condition that makes the participant unsuitable for participation. * History of significant liver disease from non-HBV or non-HDV etiology * History of allergic reactions, hypersensitivity, or intolerance to study drug, its metabolites, or excipients. * History of anaphylaxis * History of immune complex disease * History of autoimmune disorder * History or evidence of alcohol or drug abuse * Prior or concomitant therapy with an immunomodulatory agent, IFN-alpha, cytotoxic or chemotherapeutic agent, or chronic corticosteroids. * Anti-HBs \>10 mIU/mL at screening