Tenofovir Alafenamide (TAF) in Children and Adolescents With Chronic Hepatitis B Virus Infection

Key Inclusion criteria:

- Males and non-pregnant, non-lactating females

- Weight at screening as follows:

- Cohort 1 = ≥ 35 kg (≥ 77 lbs)

- Cohort 2 Group 1 = ≥ 25 kg (≥ 55 lbs)

- Cohort 2 Group 2 = ≥ 17 kg to < 25 kg (≥ 37 lbs to <55 lbs)

- Cohort 2 Group 3 = < 17 kg (< 37 lbs)

- Willing and able to provide written informed consent/assent (child and parent/legal
guardian)

- Documented evidence of CHB (eg, HBsAg-positive for ≥ 6 months)

- Treatment-naive or treatment-experienced will be eligible for enrollment.

- Estimated creatinine clearance (CLCr) ≥ 80 mL/min/1.73m^2 (using the Schwartz formula)

- Normal ECG

Key Exclusion criteria:

- Females 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.

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

- Evidence of hepatocellular carcinoma (Note: if screening alpha-fetoprotein (AFP) is <
50 ng/mL no imaging study is needed; however, if the screening AFP is > 50 ng/mL an
imaging study is required)

- Any history of, or current evidence of, clinical hepatic decompensation

- Abnormal hematological and biochemical parameters

- Chronic liver disease of non-HBV etiology (e.g., hemochromatosis, alpha-1 antitrypsin
deficiency, cholangitis)

- Received solid organ or bone marrow transplant

- Currently receiving therapy with immunomodulators (eg, corticosteroids), or
immunosuppressants

- Significant renal, cardiovascular, pulmonary, or neurological disease in the opinion
of the Investigator

- Malignancy within the 5 years prior to screening. Individuals under evaluation for
possible malignancy are not eligible.

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

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