Efficacy and Safety of Switching From TDF to TAF in Adults With Chronic Hepatitis B Who Are Virologically Suppressed

Key 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

- Adult male and non-pregnant, non-lactating females

- Documented evidence of chronic HBV infection previously

- Maintained on TDF 300 mg QD for at least 48 weeks, and as monotherapy for chronic
hepatitis B for at least 24 weeks with viral suppression (HBV DNA < LLOQ) for a
minimum of 12 weeks prior to screening

- Adequate renal function

- Normal ECG

Key Exclusion Criteria:

- Pregnant women or women who are breastfeeding

- Males and females of reproductive potential who are unwilling to use an "effective",
protocol-specified method(s) of contraception during the study.

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

- Evidence of hepatocellular carcinoma

- Current evidence of, or recent (≤ 5 year) history of clinical hepatic decompensation

- Abnormal hematological and biochemical parameters, including:

- Hemoglobin < 10 g/dL

- Absolute neutrophil count < 750/mm^3

- Platelets ≤ 50,000/mm^3

- Aspartate aminotransferase (AST) or ALT > 5 × upper limit of the normal range
(ULN)

- Albumin < 3.0 mg/ dL

- International normalized ratio (INR) > 1.5 × ULN (unless stable on anticoagulant
regimen)

- Total bilirubin > 2.5 × ULN

- Received solid organ or bone marrow transplant

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

- Currently receiving therapy with immunomodulators (eg, corticosteroids), nephrotoxic
agents, or agents capable of modifying renal excretion

- Individuals receiving ongoing therapy with drugs not to be used with tenofovir
alafenamide or tenofovir disoproxil fumarate or individuals with a known
hypersensitivity to study drugs, metabolites, or formulation excipients

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

- Any other clinical condition or prior therapy that, in the opinion of the
investigator, would make the individual unsuitable for the study or unable to comply
with dosing requirements.

- Use of investigational agents within 3 months of screening, unless allowed by the
sponsor

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