Characterization of viral rebounds on dual etravirine/raltegravir maintenance therapy (ANRS-163 ETRAL trial).

Background: The ANRS-163 ETRAL trial, a switch study to an etravirine 200 mg/raltegravir 400 mg twice-daily regimen in 165 patients with HIV-1 infection, showed durable efficacy until Week 96. The aim of this work was to investigate in detail the virological rebounds (VRs), defined as at least one plasma HIV viral load (VL) >50 copies/mL. Methods: Quantification of HIV-DNA level was assessed at baseline, Week 48 and Week 96 (n=157). VLs were measured in seminal plasma at Week 48 (n=26). Genotypic resistance testing by ultra-deep sequencing (UDS) for reverse transcriptase (RT) and integrase regions was performed at baseline and at the time of VR. Results: In this study, 19 patients experienced VR, with 2 patients having virological failure (VF; two consecutive VLs >50 copies/mL). For the first patient with VF, UDS detected minority resistant variants only in RT (K103N, 9.6%; Y181C, 4.9%) at baseline. Some RT variants became dominant at VF (K101E, 86.3%; Y181C, 100.0%; G190A, 100.0%) and others emerged in integrase (Y143C, 2.4%; Q148R, 6.2%; N155H, 18.8%). For the second patient with VF, neither RT nor integrase mutations were detected at baseline and VF. Median HIV-DNA level was similar at baseline, Week 48 and Week 96 (2.17, 2.06 and 2.11 log(10) copies/10(6) cells, respectively). Only one patient had a detectable seminal HIV VL (505 copies/mL). Conclusions: The dual etravirine/raltegravir regimen as maintenance therapy was effective and the emergence of mutations in cases of VF was similar to that seen in other dual-regimen studies. No HIV-DNA level modification was evidenced by Week 96.