This study will evaluate the non-inferiority of Stribild® (elvitegravir/cobicistat/ emtricitabine/tenofovir disoproxil fumarate (E/C/F/TDF)) single-tablet regimen (STR) relative to regimens consisting of a protease inhibitor (PI) boosted with ritonavir (RTV) plus Truvada® (FTC/TDF) fixed-dose combination in maintaining HIV-1 RNA < 50 copies/mL at Week 48 in virologically suppressed, HIV-1 infected adults. This study will also evaluate the safety, tolerability, and efficacy of the two regimens through 96 weeks of treatment.

Inclusion Criteria:

• Ability to understand and sign a written informed consent form
• Be on a stable antiretroviral regimen consisting of a ritonavir boosted PI plus FTC/TDF continuously for ≥ 6 consecutive months preceding the screening visit
• Be on the first or second antiretroviral drug regimen documented undetectable plasma HIV 1 RNA levels for ≥ 6 months preceding the screening visit
• No previous use of any approved or experimental integrase strand transfer inhibitor (INSTI) for any length of time
• Documented historical genotype prior to starting initial antiretroviral therapy showing no known resistance to TDF or FTC
• HIV RNA < 50 copies/mL at screening
• Normal ECG
• Hepatic transaminases ≤ 5 × the upper limit of the normal range (ULN)
• Total bilirubin ≤ 1.5 mg/dL, or normal direct bilirubin
• Adequate hematologic function
• Serum amylase ≤ 5 × ULN
• Estimated glomerular filtration rate ≥ 70 mL/min
• Females of childbearing potential must agree to utilize highly effective contraception methods, or be nonheterosexually active, practice sexual abstinence from screening throughout the duration of the study period and for 30 days following the last dose of study drug
• Female participants 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
• Male participants must agree to utilize a highly effective method of contraception during heterosexual intercourse from the screening visit, throughout the duration of the study and for 30 days following discontinuation of investigational medicinal product, or must be nonheterosexually active, or practice sexual abstinence
• Age ≥ 18 years

Exclusion Criteria:

• A new AIDS-defining condition diagnosed within the 30 days prior to screening
• Females who are breastfeeding
• Positive serum pregnancy test (female of childbearing potential)
• Receiving drug treatment for hepatitis C, or participants who are anticipated to receive treatment for hepatitis C during the course of the study
• Experiencing decompensated cirrhosis
• Have an implanted defibrillator or pacemaker
• Current alcohol or substance abuse that would interfere with compliance
• A history of malignancy within the past 5 years or ongoing malignancy other than cutaneous Kaposi's sarcoma, basal cell carcinoma, or resected, noninvasive cutaneous squamous carcinoma
• Active, serious infections requiring parenteral antibiotic or antifungal therapy within 30 days prior to Baseline, except for intramuscular penicillin for the treatment of syphilis
• Have been treated with immunosuppressant therapies or chemotherapeutic agents within 3 months of study screening, or expected to receive these agents or systemic steroids during the study
• Receiving ongoing therapy with any of the medications, including drugs not to be used with elvitegravir, cobicistat, FTC, or TDF; or those with any known allergies to the excipients of E/C/F/TDF tablets, or FTC/TDF tablets
• No anticipated need to initiate drugs during the study that are contraindicated
• Receiving other investigational drugs
• Participation in any other clinical trial
• Any other clinical condition or prior therapy that would make the participant unsuitable for the study or unable to comply with the dosing requirements

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