Study to Assess Efficacy and Safety of Bulevirtide in Combination With Pegylated Interferon Alfa-2a in Participants With Chronic Hepatitis Delta (CHD)

Inclusion Criteria

• Provision of signed and dated informed consent form.
• Positive serum hepatitis delta virus (HDV) antibody results or polymerase chain reaction (PCR) results for serum/ plasma HDV ribonucleic acid (RNA )for at least 6 months before screening.
• Positive PCR results for serum/ plasma HDV RNA at screening.
• Alanine transaminase level >1 x upper limit of normal (ULN), but less than 10 x ULN.
• Serum albumin >28 g/L.
• Thyroid stimulating hormone (TSH) within normal ranges (including on medication for control of thyroid function)
• Negative urine pregnancy test for females of childbearing potential.
• Inclusion criteria for female individuals:
• Postmenopausal for at least 2 years, or
• Surgically sterile (total hysterectomy or bilateral oophorectomy, bilateral tubal ligation, staples, or another type of sterilization), or
• Abstinence from heterosexual intercourse throughout the treatment period, or
• Willingness to use highly effective contraception (double barrier method or barrier contraception in combination with hormonal or intrauterine contraceptive) throughout the treatment period and for 6 months after the last dose of the study medication.
• Male individuals must agree to use a highly effective contraception (double barrier method or barrier contraception in combination with hormonal or intrauterine contraceptive used by female partners) and not to donate sperm throughout the treatment period and for 6 months after the last dose of the study medication.

Exclusion Criteria

• Child-Pugh hepatic insufficiency score of B-C or over 6 points. Note: Child-Pugh hepatic insufficiency score of 6 points is allowed. Only individuals with compensated cirrhosis are allowed. Uncomplicated oesophageal varices allowed; individuals with current bleeding or ligation, or history of bleeding or ligation within the last 2 years are excluded.
• Hepatitis C virus (HCV) or human immunodeficiency virus (HIV) coinfection. Individuals with HCV antibodies can be enrolled, if screening HCV RNA test is negative.
• Creatinine clearance 150 mm Hg and/ or diastolic blood pressure > 100 mm Hg at Screening.
• Previous or unstable concurrent diseases or conditions that prevent individual's enrolment into the study.
• Individuals with mental disorders or social circumstances that preclude them from following protocol requirements.
• Current or previous decompensated liver disease, including coagulopathy, hepatic encephalopathy and esophageal varices hemorrhage.
• One or more additional known primary or secondary causes of liver disease, other than hepatitis B (e.g., alcoholism, autoimmune hepatitis, malignancy with hepatic involvement, hemochromatosis, alpha-1 antitrypsin deficiency, Wilson's Disease, other congenital or metabolic conditions affecting the liver, congestive heart failure or other severe cardiopulmonary disease, etc.). Gilbert's syndrome, a benign disorder associated with low-grade hyperbilirubinemia, will not exclude individauls from participation in this trial. Autoimmune hepatitis stigmata attributed to HDV infection in the opinion of the investigator are allowed.
• White blood cells (WBC) count < 3000 cells/mm^3 (<1500 if African individuals).
• Absolute neutrophil count < 1500 cells/mm^3 (<1000 if African individuals).
• Platelet count < 90,000 cells/mm^3.
• Haemoglobin < 12 g/dL.
• Use of prohibited psychotropic agents at Screening.
• Use of interferons within 6 months before Screening.
• History of solid organ transplantation.
• Current alcohol abuse or alcohol abuse within 6 months prior to enrolment in this study; current drug addict or history of drug use within 2 years prior to Screening.
• History of disease requiring regular use of systemic glucocorticosteroids (inhalative glucocorticosteroids are allowed) or other immunosuppressants.
• Pregnant or breast-feeding females.
• Participation in another clinical study with investigational drugs within 30 days prior to randomization.
• Receipt of bulevirtide