Study to Evaluate Switching From Regimens Consisting of a Ritonavir-boosted Protease Inhibitor Plus Emtricitabine/Tenofovir Fixed-Dose Combination to the Elvitegravir/Cobicistat/Emtricitabine/Tenofovir DF Single-Tablet Regimen in Virologically Suppressed, HIV-1 Infected Patients

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