Durability of switch regimens based on rilpivirine or on integrase inhibitors, both in association with tenofovir and emtricitabine, in HIV-infected, virologically suppressed patients

BACKGROUND Switch strategies based on rilpivirine/tenofovir/emtricitabine or on an integrase inhibitor (InSTI) plus tenofovir/emtricitabine have never been compared in randomized clinical trials. The main aim of the study was to investigate the durability of these two switch regimens in virologically suppressed, HIV-infected patients. METHODS Retrospective analysis of patients who started rilpivirine or an InSTI (both with tenofovir and emtricitabine) with <50 HIV-RNA copies/mL and had at least one HIV-RNA assessed while receiving the study regimen. Virological failure (VF) was defined as two consecutive measurements of HIV-RNA >50 copies/mL. Treatment failure (TF) was define as either VF or discontinuation of any drug of the regimen. Durability was assessed by the Kaplan-Meier method and compared by Log-rank test. Residual viremia was defined as any detectable HIV-RNA below 50 copies/mL, as assed by a real-time PCR assay. RESULTS Six hundred seventy-five patients (466 switched to a rilpivirine-, 209 switched to an InSTI-based regimen [18% dolutegravir, 39% raltegravir, 43% elvitegravir/cobicistat] were included in the analysis. The median (interquartile range, IQR) follow-up in the rilpivirine and in the InSTI group was 16.7 (8.8-22.2) and 10.4 (5.4-19.6) months. The 1-year cumulative probabilities (95%CI) of VF and TF were 0.97% (0.36%-2.62%) and 9.73% (7.21%-13.06%) in the rilpivirine group and 1.83% (0.57%-5.77%) and 8.75% (5.25%-14.4%) in the InSTI group, with no difference between groups (p = 0.328 and 0.209 for VF and TF). The proportion of time spent with residual viremia was comparable in the two groups (9% [IQR 0.5%-49%] and 17% [IQR 0.5%-50%] in the rilpivirine and in the InSTI group, p = 0.087). By the multivariable Cox regression model, TF was independently associated with being on therapy with a protease inhibitor vs. a non-nucleoside reverse transcriptase inhibitor at switch (AHR = 0.52; 95%CI = 0.31-0.90; p = 0.018), baseline total/HDL-cholesterol ratio (AHR = 1.19 per 0.5-units increments; 95%CI = 1.06-1.34; p = 0.004), baseline estimated glomerular filtration rate (AHR = 0.78 per 10-units increments; 95%CI = 0.67-0.90; p = 0.001) and baseline hemoglobin (AHR = 0.78 per 1-unit increments; 95%CI = 0.64-0.94; p = 0.009), but not with treatment group (rilpivirine vs. InSTI). CONCLUSIONS In our clinical practice, the durability of the two regimens was comparable and both showed a very low probability of VF.