Therapeutic drug monitoring of boosted PIs in HIV-positive patients: undetectable plasma concentrations and risk of virological failure

Background

Therapeutic drug monitoring (TDM) of antiretroviral drugs is performed in selected HIV-positive patients. The aim of this study was to estimate the prevalence of undetectable plasma concentrations of ritonavir and boosted PIs and to evaluate the association between those and the 48 week risk of virological failure.

Methods

A TDM registry study and a retrospective follow-up study were conducted. Plasma concentrations were measured through validated methods. According to PI and ritonavir concentrations, patients were stratified as adherent, partially non-adherent or non-adherent. Virological outcome was evaluated 48 weeks afterwards.

Results

The TDM registry study included 2468 samples collected from 723 patients (68.1% male, median age 43.5 years). Eighty-seven samples (3.5%, 74 patients) and 68 samples (2.8%, 52 patients) were in the partially non-adherent and non-adherent groups, respectively; more patients on atazanavir/ritonavir (7.9%) versus darunavir/ritonavir (2% twice daily and 1.9% once daily) and lopinavir/ritonavir (1.5%; P  <   0.001) were observed in the partially non-adherent group. Two hundred and ninety patients were included in the follow-up study (64.1% male, median age 40 years). Patients in the adherent group had a higher chance of viral control [81.9% (167/204)] versus the partially non-adherent group and the non-adherent group [71.7% (33/46) and 53.1% (17/32), respectively; P  =   0.001]. Based on multivariate analysis, baseline HIV RNA >50 copies/mL ( P  <   0.001), genotypic susceptibility score ≤2 ( P  =   0.001), lower nadir CD4 cell count ( P  =   0.003) and not being in the adherent group ( P  =   0.029) were independent predictors of HIV RNA >50 copies/mL at 48 weeks.

Conclusions

The measurement of PI and ritonavir plasma levels can uncover incomplete compliance with treatment; TDM may represent a useful tool for identifying patients in need of adherence-promoting interventions.

Adherence profiles and therapeutic responses of treatment-naive HIV-infected patients starting boosted atazanavir-based therapy in the ANRS 134-COPHAR 3 trial

The adherence profile of HIV-infected patients predicts the therapeutic outcome, in particular during the early phase of antiretroviral therapy (ART). We conducted a prospective observational multicenter trial monitoring adherence and virological and immunological parameters over the initial 6 months of treatment. Thirty-five subjects were starting a treatment regimen including atazanavir, ritonavir, and emtricitabine-tenofovir. Adherence was assessed using self-completed questionnaires, announced pill counts, and the medication event monitoring system (MEMS) for each drug. Three MEMS measures were defined: the percentages of doses taken, days with the correct dosing, and doses taken on time (± 3 h). Dynamic virological suppression (DVS) was defined as a reduction in the plasma HIV-RNA level of >1 log10 per month or <40 copies/ml. The cumulative treatment time was 5,526 days. A high level of adherence was observed. The MEMS-defined adherence for correct dosing (-0.68% per 4-week period, P < 0.03) and timing compliance (-1.60% per 4-week period, P < 0.003) decreased significantly over time. The MEMS-defined adherence data were concordant with the pill counts during the trial but not with the data from the questionnaires. The median [range] percentages of doses taken (100% [50 to 102]), days with the correct dosing (95% [41 to 100]), and doses taken on time (86% [32 to 100]) were significantly associated with DVS in separate models. Among these three measures, the percentage of doses taken on time had the greatest ability to predict DVS. Timing compliance should be supported to optimize DVS during the early phase of treatment by once-daily boosted protease inhibitor-based ART. (This study has been registered at ClinicalTrials.gov under registration no. NCT00528060.).

Broadening the perspective when assessing evidence on boosted protease inhibitor-based regimens for initial antiretroviral therapy

Several national and international guidelines recommend the use of antiretroviral therapy containing a protease inhibitor (PI) with ritonavir (RTV) boosting for human immunodeficiency virus (HIV)-infected treatment-naïve patients. RTV-boosted PIs such as lopinavir (LPV/r), atazanavir (ATV + RTV), darunavir (DRV + RTV), fosamprenavir (FPV + RTV), and saquinavir (SQV + RTV) are usually recommended in regimens for initial therapy. The guideline recommendations are generally based on the clinical efficacy of the regimens. A broadened perspective of assessing the evidence related to selection of a PI for optimal first-line therapy might consider additional factors for evaluation, such as effectiveness in actual clinical practice and cost-effectiveness of individual drugs in formulating recommendations. Among the guideline-recommended PIs, LPV/r is one of the earliest PIs approved, has been a well-recognized boosted PI for treatment-naïve patients in all guidelines, and demonstrates the most evidence on long-term clinical and economic effectiveness. Studies have shown its efficacy in various controlled and real-world settings in different populations, the relationship of adherence to virologic efficacy, and the implications of resistance when used in sequence with other PI regimens. In the absence of published evidence for other guideline-recommended PIs that will greatly facilitate a fully transparent, comparative effectiveness evaluation, the cumulative evidence from this broader perspective indicates all PIs should not be viewed as equally safe and effective across all patients for initial therapy, nor should any single PI within the class be considered preferred for all treatment-naïve patients.

Suboptimal adherence to darunavir/ritonavir has minimal effect on efficacy compared with lopinavir/ritonavir in treatment-naive, HIV-infected patients: 96 week ARTEMIS data

OBJECTIVES

To examine how treatment adherence differences in ARTEMIS (96 week analysis) affected clinical outcome, and to assess factors impacting adherence.

PATIENTS AND METHODS

ARTEMIS is a Phase III trial, in HIV-1-infected treatment-naive patients, comparing efficacy and safety of once-daily darunavir/ritonavir (800/100 mg) versus lopinavir/ritonavir (800/200 mg total daily dose), each with a fixed-dose background tenofovir and emtricitabine regimen. Self-reported treatment adherence was assessed using the Modified Medication Adherence Self-Report Inventory (M-MASRI). In post-hoc analyses, mean adherence from weeks 4-96 was used to assess overall adherence for each patient, and transformed into a binary variable (>95% , adherent; < or = 95% , suboptimally adherent).

RESULTS

Overall adherence was high: 83% of darunavir/ritonavir-treated patients and 78% of lopinavir/ritonavir-treated patients were >95% adherent. The difference in virological response rate for adherent versus suboptimally adherent patients was smaller for darunavir/ritonavir (6% difference: 82% versus 76%, P = 0.3312) than for lopinavir/ritonavir (25% difference: 78% versus 53%, P < 0.0001). In suboptimally adherent patients, a higher virological response rate was seen with darunavir/ritonavir (76%) versus lopinavir/ritonavir (53%) (P < 0.01). Suboptimally adherent patients (both treatment groups) reported more adverse events (AEs), including gastrointestinal AEs, than adherent patients. Darunavir/ritonavir had a lower rate of AEs, including gastrointestinal AEs, than lopinavir/ritonavir, in adherent and suboptimally adherent patients.

CONCLUSIONS

Suboptimal adherence had no significant effect on the virological response rate with once-daily darunavir/ritonavir treatment. In contrast, the lopinavir/ritonavir response rate was significantly reduced in suboptimally adherent patients compared with adherent patients. Once-daily darunavir/ritonavir resulted in a higher virological response rate in suboptimally adherent patients compared with lopinavir/ritonavir.