This study will evaluate the efficacy of switching from emtricitabine/tenofovir disoproxil fumarate (FTC/TDF) fixed dose combination (FDC) to emtricitabine/tenofovir alafenamide (F/TAF) FDC in HIV-1 positive participants who are virologically suppressed on regimens containing FTC/TDF.

This study will consist of a 96 week double-blind treatment period. After Week 96, all participants will continue on blinded study drug treatment and attend visits every 12 weeks until treatment assignments are unblinded. All participants will return for an unblinding visit and will be given the option to receive open-label F/TAF and attend visits every 12 weeks until F/TAF is commercially available, or the sponsor terminates the F/TAF clinical development program.

Key Inclusion Criteria:

• Ability to understand and sign a written informed consent form, which must be obtained prior to initiation of study procedures
• Currently receiving antiretroviral regimen containing FTC/TDF in combination with one third agent for ≥ 6 consecutive months prior to screening.
• Plasma HIV-1 RNA levels < 50 copies/mL for at least 6 months preceding the screening visit (measured at least twice using the same assay) and not experienced two consecutive HIV-1 RNA above detectable levels after achieving a confirmed (two consecutive) HIV-1 RNA below detectable levels on the current regimen in the past year.
• Plasma HIV-1 RNA should be < 50 copies/mL at the screening visit.
• Normal electrocardiogram (ECG)
• Estimated glomerular filtration rate (eGFR) ≥ 50 mL/min according to the Cockcroft-Gault formula for creatinine clearance
• Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 5 × the upper limit of the normal range (ULN)
• Total bilirubin ≤ 1.5 mg/dL, or normal direct bilirubin (individuals with documented Gilbert's syndrome or with Atazanavir-associated hyperbilirubinemia may have total bilirubin up to 5 x ULN)
• Adequate hematologic function
• Serum amylase ≤ 5 × ULN
• Females of childbearing potential must agree to utilize highly effective contraception methods or be non-heterosexually active, or practice abstinence from screening throughout the duration of the study treatment and for 30 days following the last dose of the study drug.
• Females who have stopped menstruating for ≥ 12 months but do not have documentation of ovarian hormonal failure must have a serum follicle stimulating hormone (FSH) level at screening within the post-menopausal range based on the Central Laboratory reference range.
• Females who utilize hormonal contraceptive as one of their birth control methods must have used the same method for at least three months prior to study dosing.
• Males must agree to utilize a highly effective method of contraception during heterosexual intercourse or be non-heterosexually active, or practice sexual abstinence from first dose throughout the study period and for 30 days following the last study drug dose.

Key Exclusion Criteria:

• A new AIDS-defining condition diagnosed within the 30 days prior to screening
• Hepatitis C virus (HCV) antibody positive and HCV RNA detectable
• Individuals experiencing decompensated cirrhosis (e.g., ascites, encephalopathy, etc.)
• Individuals receiving ongoing treatment with bisphosphonate to treat bone disease (eg, osteoporosis)
• Females who are breastfeeding
• Positive serum pregnancy test
• Have an implanted defibrillator or pacemaker
• Current alcohol or substance use judged by the investigator to potentially interfere with study compliance
• A history of malignancy within the past 5 years (prior to screening) or ongoing malignancy other than cutaneous Kaposi's sarcoma (KS), basal cell carcinoma, or resected, non-invasive cutaneous squamous carcinoma.
• Active, serious infections (other than HIV-1 infection) requiring parenteral antibiotic or antifungal therapy within 30 days prior to Day 1 Visit
• Individuals receiving ongoing therapy with any of the medications not to be used with FTC, TAF, TDF or other antiretroviral third agents.

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

Qualified external researchers may request IPD for this study after study completion. For more information, please visit our website at https://www.gilead.com/science-and-medicine/research/clinical-trials-transparency-and-data-sharing-policy

18 months after study completion

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After conclusion of the study and without prior written approval from Gilead, investigators in this study may communicate, orally present, or publish in scientific journals or other media only after the following conditions have been met:

• The results of the study in their entirety have been publicly disclosed by or with the consent of Gilead in an abstract, manuscript, or presentation form; or
• The study has been completed at all study sites for at least 2 years