Safety and Efficacy of GS-9620 for the Treatment of Chronic Hepatitis B Virus in Virally-Suppressed Subjects

Inclusion Criteria:

- Must have the ability to understand and sign a written informed consent form; consent
must be obtained prior to initiation of study procedures

- Documented evidence of chronic HBV infection (e.g. HBsAg positive for more than 6
months) with detectable HBsAg levels at screening

- Have been on approved HBV OAV treatment for ≥ 1 year prior to screening, with HBV DNA
below lower limit of quantitation (LLOQ), measured at least once, 6 or more months
prior to screening, and HBV DNA < 20 IU/ml at screening

- Currently taking an approved HBV OAV (tenofovir, entecavir, adefovir, lamivudine or
telbivudine, either as single agents or in combination) with no change in regimen for
3 months prior to screening

- Willing to provide blood sample for toll-like receptor 7 (TLR-7) and interleukin 28 B
(IL28B) single-nucleotide polymorphism (SNP) assessment

- Must be willing and able to comply with all study requirements

Exclusion Criteria:

- Extensive bridging fibrosis or cirrhosis

- Lab parameters not within defined thresholds for neutropenia, anemia,
thrombocytopenia, leukopenia, or other evidence of inadequate liver function

- Co-infection with hepatitis C virus (HCV), HIV, or hepatitis D virus (HDV)

- Evidence of hepatocellular carcinoma

- Malignancy within 5 years prior to screening, with the exception of specific cancers
that are cured by surgical resection (basal cell skin cancer, etc). Participants
under evaluation for possible malignancy are not eligible

- Significant cardiovascular, pulmonary, or neurological disease

- Any of the following conditions that may worsen in response to interferon (IFN):

- Autoimmune disease (e.g. lupus erythematosus, rheumatoid arthritis, inflammatory
bowel disease, sarcoidosis, moderate or severe psoriasis)

- Poorly controlled diabetes mellitus

- Significant psychiatric disorders

- Thyroid disorder (unless controlled under treatment)

- Significant pulmonary diseases (e.g. chronic obstructive pulmonary disease)

- Retinal disease

- Immunodeficiency disorders

- Received solid organ or bone marrow transplant

- Received prolonged therapy with immunomodulators (e.g. corticosteroids) or biologics
(e.g. monoclonal Ab, interferon) within 3 months of screening

- Use of another investigational agents within 3 months of screening

- Current alcohol or substance abuse judged by the investigator to potentially
interfere with compliance

- Females who are pregnant or may wish to become pregnant during the study