Durability of lopinavir/ritonavir monotherapy in individuals with viral load ≤50 copies/ml in an observational setting

Background: The main objective is to evaluate the efficacy and durability of lopinavir-ritonavir monotherapy (LPV/r-MT) in virologically controlled HIV-positive individuals switching from combination antiretroviral therapy (cART). Methods: Criteria to be included in this observational study were to have initiated for the first time LPV/r-MT after ≥2 consecutive HIV RNA≤50 copies/ml achieved on a ≥3-drug-including regimen. The main end points were time to virological rebound (VR; defined in two ways: time of first of two consecutive viral load [VL]>50 and >200 copies/ml), time to discontinuation/intensification 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 LPV/r-MT to event or last available VL. Kaplan-Meier curves and Cox regression analyses were used. Results: A total of 228 individuals were included: median age 46 years (IQR 40-50), 36% females, 36% intravenous drug users and 25% HCV-coinfected. Median CD4+ T-cell count at nadir was 215 cell/mm3 (IQR 116-336) and at baseline was 615 cell/mm3 (IQR 436-768). By 36 months after switching to LPV/r-MT, the proportion of individuals with VR (confirmed VL>200 copies/ml) was 11% and with TF was 35%. In the multivariable Cox model the factors associated with a lower risk of TF was the duration of viral suppression <50 copies/ml prior to baseline (ARH=0.92; 95% CI 0.85, 0.99; P=0.024, per 6 months longer) and having LPV/r as part of last cART (ARH=0.45; 95% CI 0.21, 0.95; P=0.037). Conclusions: In daily clinical practice, we confirm a relatively safe approach of treatment simplification to LPV-MT in a selected population with long-lasting virological control