Study of Bictegravir/Lenacapavir in Children and Adolescents With HIV-1

Key Inclusion Criteria:

• Age and body weight at screening:

• Cohort 1: ≥ 12 years to < 18 years weighing ≥ 35 kg.

• Cohort 2: ≥ 6 years to < 12 years weighing ≥ 25 kg to < 35 kg.

• Cohort 3: ≥ 2 years to < 6 years weighing ≥ 10 kg to < 25 kg.

• On a complex ARV regimen. Complex regimens are any ARV therapy that is not asingle-tablet regimen taken once daily (eg, > 1 tablet or any other formulation aday).

• Documented plasma HIV-1 ribonucleic acid (RNA) levels must be < 50 copies/mL (orundetectable HIV-1 RNA level according to the local assay being used if the limit ofdetection is < 50 copies/mL) in the last 6 months prior to screening (at least 1measure prior to screening).

• Plasma HIV-1 RNA levels < 50 copies/mL at screening.

• No documented or suspected resistance to integrase strand transfer inhibitors (mutations T66A/I/K, E92G/Q/V, G118R, F121C/Y, G140R, Y143C/H/R, S147G, Q148H/K/R,N155H/S, or R263K in the integrase gene).

• The following laboratory parameters at screening:

• Estimated glomerular filtration rate ≥ 30 mL/min/1.73 m2 using the BedsideSchwartz formula.

• Absolute neutrophil count > 0.50 cells/L (> 500 cells/mm3).

• Hemoglobin ≥ 85 g/L (> 8.5 g/dL).

• Platelets ≥ 50 cells/L (≥ 50,000 cells/mm3).

• Hepatic transaminases (aspartate aminotransferase and alanine aminotransferase) ≤ 5 x upper limit of normal.

• Total bilirubin ≤ 23 μmol/L (≤ 1.5 mg/dL) and direct bilirubin ≤ 7 μmol/L (≤ 0.4 mg/dL).

Key Exclusion Criteria:

• CD4 cell count < 200 cells/mm^3.

• CD4 percentage < 20%.

• Life expectancy ≤ 1 year.

• An opportunistic illness indicative of Stage 3 HIV diagnosed within the 30 daysprior to screening.

• Evidence of active pulmonary or extrapulmonary tuberculosis within 3 months prior toscreening.

• Acute hepatitis within 30 days prior to screening.

• Positive hepatitis C virus (HCV) antibody with detectable HCV RNA (participantspositive for HCV antibody will have an HCV RNA test performed).

• Positive hepatitis B surface antigen (HBsAg) or positive hepatitis B virus (HBV)core antibody (antibody against hepatitis B core antigen [anti-HBc]) at screening.If a participant is negative for HBsAg and positive for anti-HBc but HBV DNA isundetectable, the participant may be enrolled.

• A history of or current decompensated liver cirrhosis (eg, ascites, encephalopathy,or variceal bleeding).Current alcohol or substance use judged by the investigator topotentially interfere with the participant's study compliance.

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