Study of Bictegravir/Emtricitabine/Tenofovir Alafenamide Fixed Dose Combination in Adolescents and Children With Human Immunodeficiency Virus-1

Key Inclusion Criteria:

Cohort 1: HIV-1 infected adolescents (12 to < 18 years of age and screening weight ≥ 35 kg) who are virologically suppressed for ≥ 6 months prior to screening. Cohort 2: HIV-1 infected children (6 to < 12 years of age and screening weight ≥ 25 kg) who are virologically suppressed for ≥ 6 months prior to screening.

Cohort 3: HIV-1 infected children (≥ 2 years of age and screening weight of ≥ 14 to < 25 kg) who are virologically suppressed for ≥ 6 months prior to screening.

Cohort 4 Group 1: HIV-1 infected children (≥ 2 years of age and screening weight of ≥ 14 to < 25 kg) who are virologically suppressed for ≥ 6 months prior to screening and unable to swallow tablets.

• Documented plasma HIV-1 ribonucleic acid (RNA) < 50 copies/mL on a stable regimen (or undetectable HIV-1 RNA level according to the local assay being used if the limit of detection is ≥ 50 copies/mL) for ≥ 6 months preceding the Screening visit. Unconfirmed virologic elevations of ≥ 50 copies/mL (transient detectable viremia, or "blip") prior to screening are acceptable. If the lower limit of detection of the local HIV-1 RNA assay is < 50 copies/mL (eg, < 20 copies/mL), the plasma HIV-1 RNA level cannot exceed 50 copies/mL on two consecutive HIV-1 RNA tests.

• Stable antiretroviral regimen of 2 nucleoside reverse transcriptase inhibitors (NRTIs) in combination with a third agent for a minimum of 6 months prior to the screening visit. Individuals undergoing dose modifications to their antiretroviral regimen for growth or who are switching medication formulation(s) are considered to be on a stable antiretroviral regimen.

• Estimated glomerular filtration rate (eGFR) ≥ 90 mL/min/1.73 m^2 according to the Schwartz Formula.

• No documented or suspected resistance to emtricitabine (FTC), tenofovir (TFV), or integrase strand transfer inhibitors (INSTIs) including, but not limited to, the reverse transcriptase resistance mutations K65R and M184V/I.

Cohort 4 Group 2-4: HIV-1 infected children (≥ 1 month of age and screening weight of ≥ 3 to < 14 kg) who are treatment naive or on antiretroviral (ARV) treatment for ≥ 1 month prior to screening.

• Positive confirmatory HIV test (confirmatory nucleic acid-based testing if < 18 months of age).

• On a stable ARV regimen for ≥ 1 month or treatment naive (Individual is considered treatment naive if ARVs were given for prevention of mother-to-child transmission but not for HIV treatment).

• For < 1 year of age, eGFR ≥ the minimum normal values for age according to the information below using the Schwartz Formula,

• 30 mL/min/1.73 m^2 for age > 4 weeks to ≤ 95 days.

• 39 mL/min/1.73 m^2 for age ≥ 96 days to ≤ 6 months.

• 49 mL/min/1.73 m^2 for age > 6 months to < 12 months.

• For ≥ 1 year of age, eGFR ≥ 90 mL/min/1.73 m^2 using the Schwartz Formula.

• No documented or suspected resistance to FTC, TFV, or INSTIs including, but not limited to, the reverse transcriptase resistance mutation K65R.

• For individuals < 14 kg, M184V/I AND HIV-1 RNA < 50 copies/mL will be allowed. Individuals with HIV-1 RNA > 50 copies/mL should not have FTC, TFV, or INSTI resistance mutations.

• Last dose of nevirapine (NVP) or efavirenz (EFV), if applicable, ≥ 14 days prior to enrollment.

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