Safety and Efficacy of GS-4774 in Combination With Tenofovir Disoproxil Fumarate (TDF) for the Treatment of Subjects With Chronic Hepatitis B and Who Are Currently Not on Treatment

Key Inclusion Criteria:

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

- Documented evidence of chronic HBV infection (e.g., HBsAg positive for more than 6
months)

- Screening HBV DNA ≥ 2000 IU/mL

- A negative serum pregnancy test is required for female subjects (unless surgically
sterile or greater than two years post-menopausal)

Key Exclusion Criteria:

- Cirrhosis

- Inadequate liver function

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

- Received antiviral treatment for HBV within 3 months of screening

- Evidence of hepatocellular carcinoma (e.g., as evidenced by recent imaging)

- Significant cardiovascular, pulmonary, or neurological disease

- Women who are pregnant or may wish to become pregnant during the course of the study

- 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 investigational agents within 3 months of screening

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

- Receipt of immunoglobulin or other blood products within 3 months prior to enrollment

- History of demyelinating disease (Guillain-Barre), Bell's Palsy, Crohn's disease,
Ulcerative colitis, or autoimmune disease

- Documented history of yeast allergy

- Known hypersensitivity to study drugs, metabolites or formulation excipients

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

Note: Other protocol defined Inclusion/Exclusion criteria may apply.