Pharmacokinetics, Safety, and Efficacy of Cobicistat-boosted Atazanavir or Cobicistat-boosted Darunavir in HIV-1 Infected, Treatment-Experienced, Virologically Suppressed Pediatric Subjects

Key Inclusion Criteria:

- HIV-1 infected treatment-experienced, virologically suppressed males and females aged
3 months to < 18 years at the Day 1 visit (according to requirements of enrolling
Cohort)

- Are able to provide written assent if they have the ability to read and write

- Parent or legal guardian able to provide written informed consent prior to any
screening evaluations and willing to comply with study requirements

- Body weight at screening ≥ 25 kg (Cohorts 1 and 2), 15 kg to < 25 kg (Cohort 2), or to
be determined (Cohorts 3 and 4) dependent upon age cohort

- Adequate renal function

- Adequate hematologic function

- Adequate hepatic function defined as

- Hepatic transaminases (AST and ALT) ≤ 5 x upper limit of normal (ULN)

- Total bilirubin ≤ 1.5 mg/dL or a normal direct bilirubin

- Negative serum pregnancy test

- Individuals with evidence of suppressed viremia (< 50 copies/mL) at study entry

- Stable antiretroviral regimen including 2 nucleoside reverse transcriptase inhibitors
and either ritonavir-boosted atazanavir or ritonavir-boosted darunavir once or twice
daily as per product label for a minimum of 3 months prior to the screening visit.
Treatment-experienced pediatric individuals taking DRV/r must have no history of DRV
resistance associated mutations.

- Males and females of childbearing potential must agree to utilize highly effective
contraception methods while on study treatment or agree to abstain from heterosexual
intercourse throughout the study period and for 30 days following the last dose of
study drug

- Documented negative screening for active pulmonary tuberculosis (TB) per local
standard of care within 6 months of a screening visit

- Must be willing and able to comply with all study requirements

- No opportunistic infection within 30 days of study entry (at Day -10)

Key Exclusion Criteria:

- Individuals with CD4+ cell counts at screening of less than 200 cells/mm^3

- An AIDS defining condition with onset within 30 days prior to screening

- Life expectancy of less than 1 year

- An ongoing serious infection requiring systemic antibiotic therapy at the time of
screening.

- Evidence of active pulmonary or extra-pulmonary tuberculosis disease:

- Within 3 months of the screening visit for all individuals 6 months of age or
older

- At anytime for individuals younger than 6 months

- Anticipated requirement for rifamycin treatment while participating in the study.
Note: prophylactic isoniazid therapy for latent TB is allowed.

- Active hepatitis C virus (HCV) infection. Note: individuals with positive HCV antibody
and without detectable HCV RNA are permitted to enroll.

- Positive Hepatitis B surface antigen or other evidence of active hepatitis B virus
(HBV) infection. Note: individuals with positive HBV surface antibody and no evidence
of active HBV infection are permitted to enroll.

- Individuals with clinically significant abnormal ECGs

- Have any serious or active medical or psychiatric illness which, in the opinion of the
investigator, would interfere with treatment, assessment, or compliance with the
protocol.

- Individuals experiencing decompensated cirrhosis

- A history of or ongoing malignancy other than cutaneous Kaposi's sarcoma (KS), basal
cell carcinoma, or resected, non-invasive cutaneous squamous carcinoma.

- Pregnant or lactating females.

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

- Have history of significant drug sensitivity or drug allergy.

- Known hypersensitivity to the study drug, the metabolites, or formulation excipients.

- Have previously participated in an investigational trial involving administration of
any investigational agent within 30 days prior to the study dosing.

- Participation in any other clinical trial, including observational studies, without
prior approval from sponsor is prohibited while participating in this trial.

- Individuals receiving ongoing therapy with any medication that is not to be taken with
COBI or a component of the BR

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