Dolutegravir-based dual maintenance regimens combined with lamivudine/emtricitabine or rilpivirine: risk of virological failure in a real-life setting

Background: Maintenance ART with dolutegravir-based dual regimens have proved their efficacy among HIV-1infected subjects in randomized trials. However, real-life data are scarce, with limited populations and follow-up. Objectives: We assessed virological failure (VF) and resistance-associated mutations (RAMs) on dolutegravir maintenance regimens in combination with rilpivirine or with lamivudine or emtricitabine (xTC) and analysed the factors associated with VF. Methods: Between 2014 and 2018, all HIV-1-infected adults included in the Dat'AIDS cohort and starting dolutegravir/rilpivirine or dolutegravir/xTC as a maintenance dolutegravir-based dual regimen were selected. VF was defined as two consecutive HIV RNA values >50 copies/mL or a single value >400 copies/mL. We compared cumulative genotypes before initiation of a maintenance dolutegravir-based dual regimen with genotype at VF. Results: We analysed 1374 subjects (799 on dolutegravir/rilpivirine and 575 on dolutegravir/xTC) with a median follow-up of 20months (IQR = 11-31) and 19months (IQR = 11-31), respectively. VF occurred in 3.8% (n = 30) of dolutegravir/rilpivirine subjects and 2.6% (n = 15) of dolutegravir/xTC subjects. Among subjects receiving dolutegravir/rilpivirine, two genotypes harboured emerging RAMs at VF: E138K on NNRTI (n = 1); and E138K!K101E on NNRTI and N155H on INSTI (n = 1). Among subjects receiving dolutegravir/xTC, no new RAM was detected. The only predictive factor of VF on dolutegravir/rilpivirine was the history of failure on an NNRTI-based regimen (adjusted HR = 2.97, 95% CI = 1.28-6.93). No factor was associated with VF on dolutegravir/xTC. Conclusions: In this large real-life cohort, dolutegravir/rilpivirine and dolutegravir/xTC sustained virological suppression and were associated with a low rate of VF and RAM emergence. Careful virological screening is essential before switching to dolutegravir/rilpivirine in virologically suppressed patients with a history of NNRTI therapy.