Inclusion Criteria:
* Male or female participants, aged 18-65 years old (inclusive)
* Body Mass Index between 19 to 35 kg/m2 (inclusive)
* Body weight \> or = 45 kg.
* Documented HBV infection for ≥6 months prior to randomization.
* For Parts A and B, on stable approved NA monotherapy for at least 6 months prior to randomization.
* For Part C and D only, not on any NA monotherapy for at least 6 months prior to randomization.
* Screening electrocardiogram (ECG) without clinically significant abnormalities
* Females of childbearing potential must not be breastfeeding, must have a negative serum pregnancy test at Screening, and a negative urine/serum pregnancy test before dosing (unless permanently sterile or \>2 years postmenopausal).
* Males and females of childbearing potential must agree to use protocol specified reliable contraception throughout the study.
* Screening HBV DNA, HBsAg and ALT must meet prespecified requirements.
Exclusion Criteria:
* Significant medical conditions other than chronic HBV (e.g. recent heart issues, unstable cardiac disease, uncontrolled diabetes, bleeding disorders, prior organ transplant).
* Other clinically significant liver diseases (e.g. hepatitis from other causes, autoimmune or alcoholic liver disease, prior liver failure).
* History of suspected or confirmed cirrhosis (based on FibroScan® or biopsy).
* Current, past, or suspected liver cancer, or elevated alpha-fetoprotein (AFP) ≥ 20 ng/mL.
* HBV-related extrahepatic diseases (e.g. kidney or vascular conditions).
* Severe infection (other than chronic HBV infection) within 1 month before randomization requiring intravenous treatment.
* Active infections: human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis D virus (HDV) or syphilis (exceptions if RNA negative).
* Abnormal lab results (e.g. low albumin, reduced kidney function, abnormal INR, low platelets, high bilirubin, abnormal blood counts, significant proteinuria).
* History or signs of vasculitis or related autoimmune diseases.
* Malignancy within 5 years (except non-melanoma skin cancer).
* Allergy to study drug components.
* Recent major surgery/trauma (within 3 months) or planned surgery during study.
* Alcohol or substance abuse affecting compliance.
* Pregnancy, breastfeeding, or unwillingness to follow reproductive restrictions.
* Participation in another clinical trial or recent investigational product use.
* Prior treatment with any antisense oligonucleotide or small interfering RNA therapies.
* Recent or ongoing use of immunosuppressive/biologic therapies, certain vaccines, bulevirtide, or unapproved herbal remedies.
* Need for long-term anticoagulants/antiplatelet drugs (unless safely stopped).
* Any other condition making the participant unsuitable (per investigator).
