Safety and Efficacy of Switching From Regimens of ABC/3TC + a 3rd Agent to E/C/F/TAF Fixed-Dose Combination (FDC) in Virologically-Suppressed HIV 1 Infected Adults

Key Inclusion Criteria: HIV-infected adult participants who meet the following criteria will be given the option to participate in the study: * Currently receiving ABC/3TC plus a third antiretroviral (ARV) agent for ≥ 6 consecutive months preceding the screening visit. For subjects with 3 or more ART regimens, a regimen history must be provided to the Sponsor for approval. Allowed third antiretroviral agents include LPV/r, ATV+RTV, ATV+COBI (or ATV/COBI FDC), DRV+RTV, DRV + COBI (or DRV/COBI FDC) FPV + RTV, SQV + RTV, ATV (no booster), EFV, RPV, NVP, ETR, RAL or DTG * Documented plasma HIV-1 RNA levels \< 50 copies/mL for ≥ 6 months preceding the screening visit (measured at least twice using the same assay). In the preceding 6 months prior to screening, one episode of "blip" (HIV-1 RNA \> 50 and \< 400 copies/mL) is acceptable, only if HIV-1 RNA is \< 50 copies/mL immediately before and after the "blip". * Plasma HIV-1 RNA \< 50 copies/mL at screening visit * Individuals will have no evidence of previous virologic failure on a PI+RTV or integrase strand transfer inhibitor-based regimen (with or without resistance to either class of ARV). * All documented historical plasma genotype(s) must not show resistance to tenofovir disoproxil fumarate (TDF) or emtricitabine (FTC), including, but not limited to the presence of reverse transcriptase resistance mutants K65R, K70E, M184V/I, or thymidine analog associated mutations (TAMs) (TAMs are: M41L, D67N, K70R, L210W, T215Y/F, K219Q/E/N/R). If a historical genotype is not available or subject has 3 or more ART regimens, subject will have proviral genotype analysis prior to Day 1 to confirm absence of archived resistance to TDF or FTC. * Adequate renal function defined as having an estimated glomerular filtration rate of ≥ 30 mL/min as calculated by Cockcroft-Gault (eGFR-CG) Note: Other protocol defined Inclusion/Exclusion criteria may apply.