Study of EYP001a to Assess Its Safety and Anti-viral Effect in CHB Patients in Combination With NA (ETV or TD)

Main Inclusion Criteria: * Are on stable NA therapy at least 12 months from the screening date (ETV or TDF) * Has virally suppressed CHB: HBV DNA \<LLOQ and serum HBsAg \>100 IU/mL * Has liver imaging to screen for hepatocellular carcinoma or concomitant pancreaticobiliary disease either in the prior 6 months or at screening. * Is not of childbearing potential or, if of childbearing potential, is not pregnant as confirmed by a negative serum human chorionic gonadotropin test at screening and is not planning a pregnancy during the course of the study. Main Exclusion Criteria: * Is an employee of a contract research organization (CRO), vendor, or Sponsor involved with this study. * Has known hepatocellular carcinoma or pancreaticobiliary disease. * Neutropenia (defined by two confirmed values within screening period of \<1500/μL). * Has Gilbert syndrome. * Shows evidence of worsening liver function, defined as either a confirmed (two assessments at least 3 days apart) increase \>2 ULN ALT or AST or an increase of \>1.5 × first assessed value of TBL or associated with clinical signs or symptoms of liver impairment. * Has known or suspected non-CHB liver disease * History of cirrhosis or liver decompensation, including ascites, hepatic encephalopathy, or presence of oesophageal varices. * Probable or possible F3 stage with a vibration controlled transient elastography (VCTE). Patients with normal baseline ALT and VCTE \>8.8 kPa are excluded. Patients with baseline ALT \>ULN (but \<2ULN per EC5) and who have VCTE \>10.5 kPa at baseline are excluded 11. * Has known history of alcohol abuse or daily heavy alcohol consumption * Has clinically relevant immunosuppression, including, but not limited to, immunodeficiency conditions such as common variable hypogammaglobulinemia. * Has used anti-HBV medications other than NAs within 90 days prior to screening. * Has any of the following exclusionary laboratory results at screening: 1. Estimated glomerular filtration rate \<60 mL/min/1.73 m2 (the Modification of Diet in Renal Disease formula). 2. Thyroid-stimulating hormone \>1.5× ULN or abnormal free triiodothyronine or free thyroxine.