536Systematic Review and Meta-Analysis of Randomized Controlled Trials (RCTs) Comparing Initial Non-Nucleoside Reverse-Transcriptase Inhibitor (NNRTI)- versus Ritonavir Boosted Protease Inhibitor (PI/r)-based Anti-Retroviral Therapy (ART)

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Comparison of Dried Blood Spots Versus Conventional Plasma Collection for the Characterization of Efavirenz Pharmacokinetics in a Large-Scale Global Clinical Trial-The ENCORE1 Study

The aim of this study was to determine the utility of dried blood spots (DBS) compared with conventional plasma collection methods for characterization of efavirenz pharmacokinetics, in the setting of a large-scale, global clinical trial (ENCORE1).Six hundred thirty patients were recruited from 38 sites and had single matched whole blood DBS and plasma samples (mid-dose interval) taken at weeks 4 and 12 of treatment. In addition, a subgroup of patients underwent intensive DBS and plasma sampling (0-24 hours) to provide full-profile data for pharmacokinetic parameters. Efavirenz concentrations were determined by validated high-performance liquid chromatography-mass spectrometry methods. A DBS-predicted plasma concentration was derived and linear regression and Bland-Altman plots were used to compare DBS-predicted plasma concentrations with that of measured plasma concentrations.Efavirenz DBS and plasma concentrations were significantly correlated (R = 0.904, P < 0.001; n = 1094), and DBS concentrations were, on average, 53% ± 9.5% lower than plasma. In the main study, the DBS-predicted plasma values significantly underestimated the true measured concentration of efavirenz in plasma; the mean difference (95% confidence interval) between efavirenz DBS-predicted concentrations and measured plasma concentrations was -0.451 mg/L (-0.504 to -0.398) at week 4 (n = 561). However, in the intensive study, the mean difference was only 0.086 mg/L (-0.006 to 0.178) at 12 hours after dose (n = 46) and was not statistically significant.Our data show a high correlation between measurements of efavirenz concentrations in plasma and in DBS. However, DBS concentrations significantly underestimated the true measured plasma concentrations in the sparse samples taken in this large multinational ENCORE1 trial

Efficacy of 400 mg efavirenz versus standard 600 mg dose in HIV-infected, antiretroviral-naive adults (ENCORE1): A randomised, double-blind, placebo-controlled, non-inferiority trial

Background: The optimum dose of key antiretroviral drugs is often overlooked during product development. The ENCORE1 study compared the efficacy and safety of reduced dose efavirenz with standard dose efavirenz in combination with tenofovir and emtricitabine as first-line treatment for HIV infection. An effective and safe reduced dose could yield meaningful cost savings. Methods: ENCORE1 is a continuing non-inferiority trial in HIV-1-infected antiretroviral-naive adults in 38 clinical sites in 13 countries. Participants (plasma HIV-RNA >1000 log copies per mL, CD4 T-cell count 50-500 cells per μL) were randomly assigned by a computer-generated sequence with a blocking factor of four (stratified by clinical site and by screening viral load) to receive tenofovir plus emtricitabine with either a reduced daily dose (400 mg) or a standard dose (600 mg) of efavirenz. Participants, physicians, and all other trial staffwere masked to treatment group. The primary endpoint was the difference in proportions of participants with plasma HIV-RNA of less than 200 copies per mL at 48 weeks. Treatment groups were regarded as non-inferior if the lower limit of the 95% CI for the difference in viral load was less than-10% by modified intention-to-treat analysis. Adverse events were summarised by treatment. This trial is registered with ClinicalTrials.gov, number NCT01011413. Findings: The modified intention-to-treat analysis consisted of 630 patients (efavirenz 400=321; efavirenz 600=309). 32% were women; 37% were African, 33% were Asian, and 30% were white. The mean baseline CD4 cell count was 273 cells per μL (SD 99) and median plasma HIV-RNA was 4.75 log copies per mL (IQR 0.88). The proportion of participants with a viral load below 200 copies per mL at week 48 was 94.1% for efavirenz 400 mg and 92.2% for 600 mg (difference 1.85%, 95% CI-2.1 to 5.79). CD4 T-cell counts at week 48 were significantly higher for the 400 mg group than for the 600 mg group (mean difference 25 cells per μL, 95% CI 6-44; p=0.01). We recorded no difference in grade or number of patients reporting adverse events (efavirenz 400=89.1%, efavirenz 600=88.4%; difference 0.75%, 95% CI-4.19 to 5.69; p=0.77). Study drug-related adverse events were significantly more frequent in the 600 mg group than in the 400 mg group (146% [47] vs 118 [37]), difference-10.5%, 95% CI-18.2 to-2.8; p=0.01) and significantly fewer patients with these events stopped treatment (400 mg=6 [2%], 600 mg=18 [6%], difference-3.96%, 95% CI-6.96 to -0.95; p=0.01). Interpretation: Our findings suggest that a reduced dose of 400 mg efavirenz is non-inferior to the standard dose of 600 mg, when combined with tenofovir and emtricitabine during 48 weeks in ART-naive adults with HIV-1 infection. Adverse events related to the study drug were more frequent with 600 mg efavirenz than with 400 mg. Lower dose efavirenz should be recommended as part of routine care

Nonnucleoside Reverse-transcriptase Inhibitor- vs Ritonavir-boosted Protease Inhibitor-based Regimens for Initial Treatment of HIV Infection: A Systematic Review and Metaanalysis of Randomized Trials

Previous studies suggest that nonnucleoside reverse-transcriptase inhibitors (NNRTIs) cause faster virologic suppression, while ritonavir-boosted protease inhibitors (PI/r) recover more CD4 cells. However, individual trials have not been powered to compare clinical outcomes