The study is an open-label, randomized, comparative, multicenter clinical trial. The purpose of this study is to assess the efficacy of ABX203, a new chronic hepatitis B therapeutic vaccine administered as an adjunct therapy to nucleos(t)ide analogs (NUCs), in maintaining control of Hepatitis B disease after cessation of treatment with NUCs in subjects with HBeAg negative chronic Hepatitis B.

Inclusion Criteria:

• Male or female subject between 18 and 65 years of age at the time of randomization.
• Must be HBeAg negative and anti-HBe Abs positive for at least 1 year prior to screening and at screening.
• Has HBV DNA < 40 IU/mL for at least 1 year prior to screening and at screening
• Has both ALT and AST levels ≤ ULN for at least 1 year prior to screening and at screening.
• Must be HBsAg positive at screening.
• Has been treated with NUCs for at least 2 years prior to screening.
• Has not been treated with PEG-IFN or IFN for at least 1 year prior to screening.
• For all females, must have a negative serum pregnancy test at screening. For female of childbearing potential, must have been using adequate contraception and must agree to continue to use it during all study period and for 6 months after completion of the study product administration.
• Has provided written informed consent.

Exclusion Criteria:

• Has elevated blood levels of alpha-fetoprotein (AFP) (> 500 ng/mL).

• Has cirrhosis, defined as

  • platelet count < 150,000/mm3, with esophageal varices on imaging and spleen size > 12, or
  • liver stiffness of 11 kilopascal [kPa] as measured by elastography using FibroScan® or .an AST to Platelet Ratio Index (APRI) > 2).

• Has hepatocellular carcinoma (HCC) (diagnosed by ultrasonography).

• Has liver decompensation (albumin < 3.5 g/dL and bilirubin ≥1.3 mg/dL).

• Is Hepatitis C virus (HCV) Ab positive at screening.

• Is Hepatitis delta virus (HDV) Ab positive at screening.

• Is Human Immunodeficiency Virus (HIV) Ab positive at screening.

• Has an immune suppressive disorder or treatment with immunosuppressive drugs.

• Has been treated with corticosteroids within 12 weeks prior to the first administration of study product, with the exception of topical or inhaled corticosteroids.

• Has been treated with rituximab.

• Has other hepatic diseases of different etiology (such as auto-immune hepatitis, toxic hepatitis, Wilson disease, alcoholic or hemochromatosis).

• Has a history of allergic disease or reactions likely to be exacerbated by any component of the study products.

• Has a history of a substance abuse (drug or alcohol) problem within the previous 3 years.