Intrahepatic and Peripheral Responses to Imdusiran (AB-729) in Chronic Hepatitis B

Inclusion criteria

• Provision of signed and dated informed consent form
• Stated willingness to comply with all study procedures and availability for the duration of the study
• Male or female, over 18 years of age on the date of screening
• In good general health as evidenced by medical history
• Documented evidence of chronic hepatitis B infection (HBsAg positive at screening and for at least more than 6 months prior to screening)
• For females of reproductive potential must have a negative serum pregnancy test at screening and a negative urine pregnancy test at baseline prior to study drug administration
• Male and female subjects of childbearing potential who engage in heterosexual intercourse must agree to use protocol specified method(s) of contraception
• Have been on commercially available HBV oral antiviral treatment(s) for at least 6 months and willing to continue through the final study visit.
• HBV Deoxyribonucleic acid (DNA) ≤ 20 IU/mL for 6 or more months prior to Screening.
• Hepatitis B surface antigen titer ≥ 100 IU/mL.
• Liver imaging without liver mass suggestive of hepatocellular carcinoma within 12 months of day 0 AND Alpha fetoprotein \<10 ng/mL within 3 months of screening.

Exclusion criteria

• Known co-infection with any of the following:
• Human immunodeficiency virus (HIV)
• Hepatitis C virus (HCV), unless subjects are HCV Ab positive, but have a documented history of completing HCV treatment and/or negative HCV RNA
• Hepatitis D virus (HDV)
• Any known preexisting medical or psychiatric condition that could interfere with the subject's ability to provide informed consent or participate in study conduct, or that may confound study
• History of cirrhosis at any time, or evidence of decompensated liver disease including, but not limited to, a history or presence of clinical ascites, bleeding esophageal varices, hepatorenal syndrome, liver transplantation and/or hepatic encephalopathy.
• Liver ultrasound or other imaging with findings suggestive of hepatocellular carcinoma (HCC) at any time.
• Clinically unstable medical condition ≤2 weeks prior to the first dose of study treatment.
• Clinical diagnosis of substance abuse with alcohol, narcotics, or cocaine within the past 12 months except for those subjects monitored in an opioid substitution maintenance program.
• Malignancy within 5 years prior to screening, with the exception of specific cancers that are cured by surgical resection (e.g. basal cell skin cancer). Subjects under evaluation for possible malignancy are not eligible.
• Extensive bridging fibrosis or cirrhosis as defined clinically, by imaging or by the following:
• a. Metavir ≥ 3 or Ishak fibrosis score ≥ 4 by a liver biopsy within 3 years of screening, or, in the absence of an appropriate liver biopsy, either: i. Screening FibroTest score \>0.48 and APRI \>1, or ii. FibroScan with a result \>9 kPa within 12 months of screening
• If liver biopsy is available, the liver biopsy result supersedes (i) and (ii).
• Subjects meeting any of the following laboratory parameters at screening:
• Alanine aminotransferase (ALT) \>3x Upper Limit of Normal (ULN)
• Direct bilirubin (if total bilirubin elevated) \>1.5 × ULN of the laboratory reference range.
• Prothrombin (PT) or Activated Partial Thromboplastin Clotting Time (APTT) over the upper limit of normal.
• Platelet count \<100,000/microliters
• Estimated glomerular filtration rate, calculated by the chronic kidney disease epidemiology collaboration formula: \<60 mL/min/1.73 m2
• Significant cardiovascular, pulmonary, or neurological disease in the opinion of the investigator.
• Participation in any investigational drug, vaccine, or device study within 30 days before study treatment administration, or 90 days for a biologic study, or at any time during participation in the study.
• Pregnancy or lactation
• Believed by the Study Investigator to be inappropriate for study participation for any reason not otherwise listed