Randomized, phase 2 evaluation of two single-tablet regimens elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate versus efavirenz/emtricitabine/tenofovir disoproxil fumarate for the initial treatment of HIV infection.

OBJECTIVE: To assess the safety and efficacy of two, single-tablet regimens for the initial treatment of HIV infection.

DESIGN: Phase 2, randomized, double-blind, double-dummy, multicenter, active-controlled study.

METHODS: Antiretroviral treatment-naive adults with a screening HIV-1 RNA at least 5000 copies/ml and a CD4 cell count more than 50 cells/μl were randomized 2: 1 to receive fixed-dose combination tablets of elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate (EVG/COBI/FTC/TDF; N = 48) or efavirenz/emtricitabine/tenofovir disoproxil fumarate (EFV/FTC/TDF; n = 23) for 48 weeks. The primary endpoint was proportion of participants with HIV-1 RNA less than 50 copies/ml at week 24.

RESULTS: Participants receiving EVG/COBI/FTC/TDF exhibited a more rapid decline in HIV-1 RNA and a greater proportion suppressed viral load to less than 50 copies/ml than participants receiving EFV/FTC/TDF. Both EVG/COBI/FTC/TDF and EFV/FTC/TDF resulted in high rates of viral suppression and increases in CD4 cell count. Ninety and 83% of participants suppressed HIV-1 RNA to less than 50 copies/ml both at the 24-week and 48-week visits for EVG/COBI/FTC/TDF and EFV/FTC/TDF, respectively. Once-daily administration of EVG/COBI/FTC/TDF provided a mean EVG trough concentration 10-fold over its protein binding-adjusted IC(95) across study visits. EVG/FTC/TDF/GS-9350 was generally well tolerated with a lower rate of drug-related central nervous system (17%) and psychiatric (10%) adverse events versus EFV/FTC/TDF (26 and 44%, respectively). Decreases in estimated glomerular filtration rate occurred within the first few weeks of dosing in participants receiving EVG/COBI/FTC/TDF, remained within the normal range and did not progress at week 24 or 48; no participant experienced a clinical adverse event or discontinued study drug due to changes in serum creatinine or renal function.

CONCLUSION: Once-daily EVG/COBI/FTC/TDF achieved and maintained a high rate of virologic suppression with fewer central nervous system and psychiatric adverse events compared to a current standard-of-care regimen of EFV/FTC/TDF.