Poster Abstracts

Background: Elvitegravir/cobicistat/emtricitabine/tenofovir DF (STRIBILD, STB), can be used for antiretroviral (ARV) treatment simplification and tolerability in HIV-1 infected patients who are virologically suppressed without prior virologic failure (VF).Week (W) 96 results of STRATEGY-PI (Study 115) are reported, the first phase 3b, open-label, study examining simplification from ritonavir (RTV)-boosted protease inhibitor (PI+RTV) plus emtricitabine/ tenofovir DF (FTC/TDF) regimens to an integrase inhibitor-containing single tablet regimen.Methods: HIV-1 infected, virologically suppressed subjects on PI+RTV + FTC/ TDF regimens for ≥ 6 months either switched to STB or remained on their PI+RTV regimen (2:1 randomization).Eligibility included estimated creatinine (Cr) clearance ≥ 70 mL/min, ≤2 prior ARV regimens, no prior VF and no resistance to FTC/TDF.The primary endpoint was the proportion of subjects who maintained HIV-1 RNA < 50 c/mL at W48 (snapshot algorithm, 12% noninferiority margin); W96 was the final endpoint.If noninferiority was established, superiority was tested (prespecified).Results: At randomization, subjects (n=433, 293 STB; 140 PI+RTV) were mostly male (86%), white (80%) and age < 50 yr (82%).ATV+RTV (40%) or DRV+RTV (40%) were the most common PIs.Median time since first ARV use was 3 yrs; 19% were on their 2nd ARV regimen.At W96, 86% STB vs 69% PI+RTV maintained HIV-RNA < 50 c/mL (difference 16.5%, 95% CI: +7.8% to +25.4%; p<0.001).The difference favouring STB was mainly due to nonvirologic reasons.VF was lower on STB (1% STB vs 5% PI+RTV), but with no emergent resistance in either group.Grade 3-4 adverse events (AE) occurred in 6% STB vs 8% PI+RTV.AEs leading to discontinuation occurred in 3% STB vs 2% PI+RTV.Median changes in serum Cr (lmol/L) were STB, +6.2, and RI+RTV, +0.9, similar to W48.One STB subject discontinued due to a renal AE after W48 (blood Cr increased).No case of proximal renal tubulopathy (PRT) occurred in either group.Conclusions: Switching to STB from PI+RTV+FTC/TDF regimens resulted in significantly higher virologic success by snapshot at W96. VF was lower on STB with no emergent resistance in either group.The difference favouring STB was mainly due to non-virologic reasons.STB was well-tolerated, and no case of PRT occurred.Simplification to STB from a multi-tablet, PI+RTV regimen is effective, durable and safe in HIV-1 infected, virologically suppressed patients without history of VF.