Durability of lopinavir/ritonavir dual-therapies in individuals with viral load <50 copies/mL in the observational setting

INTRODUCTION: We aimed at evaluating the efficacy and durability of a lopinavir/ritonavir-based dual regimen (LPV/r-DR) in virologically controlled HIV-infected individuals in current clinical practice. METHODS: Patients who have initiated for the first time a LPV/r-DR with HIV-RNA<50 copies/mL were included in this observational study. The main endpoints were: time to virological rebound [VR=time of first of two consecutive viral loads (VL)>50 copies/mL] and time to experience either a single VL>200 copies/mL or discontinuation/intensification (= treatment failure, TF). Individuals’ follow-up accrued from the date of starting the LPV/r-DR to event or last available VL. Kaplan-Meier curves and Cox regression analysis were used. Covariates included in the multivariable analysis were gender, age, route of transmission, hepatitis co-infection, calendar year of starting the DR, nadir CD4+ count, VL at initiation of first cART, previous failures to protease inhibitors (PIs), time with undetectable VL before starting the DR and the type of DR [nucleoside reverse transcriptase (NRTI), non-NRTI (NNRTI), raltegravir or maraviroc, with NRTI as reference group]. Results are presented as median (Q1, Q3) or frequency (%) as appropriate. RESULTS: 108 individuals followed for 18 (7, 30) months were included; baseline (BL) characteristics are detailed in Table 1. LPV/r was associated with a NRTI in 51, with a NNRTI in 10, with raltegravir in 29, and with maraviroc in 18 individuals. By 36 months from switching to the LPV/r-DR, the proportion of individuals with VR and TF was 10% (95% CI 3–17%) and 36% (95% CI 22–50%), respectively. We did not find any factor independently associated with the risk of VR. Older age (ARH=0.49 (95% CI 0.30–0.78) per 10 years older; p=0.003) was found to be protective from TF. Mean (SE) CD4+ cells/µL increase from BL to month 36 resulted significant: 195 (40.1) cells/µL (p=0.0028). We did not observe significant changes in AST, ALT, eGFR (MDRD formula), triglycerides and both total and HDL-cholesterol. CONCLUSIONS: A LPV/r-DR can be considered a valuable option in patients with HIV-RNA<50 copies/mL and ongoing toxicity from the third drug of the regimen, although up to 17% of patients showed viral rebound by 3 years. Older patients are at lower risk of failure with this strategy, but larger sample size is needed to identify who might benefit from this strategy instead of others.