Predictors of 007 triphosphate concentrations in dried blood spots in persons with hepatitis C and active drug or alcohol use.

BACKGROUND: Sofosbuvir is converted to its active form, 007 triphosphate (007-TP), within cells. To date, the association between treatment adherence and 007-TP in dried blood spots (DBS) and factors that influence this relationship remain unknown. OBJECTIVES: To examine relationships between adherence and 007-TP concentrations in DBS and identify factors that influence 007-TP in DBS. METHODS: Persons with HCV or HIV/HCV coinfection and self-reported drug and/or alcohol use were randomized to one of two technology-based approaches for monitoring 12 week adherence to once-daily ledipasvir/sofosbuvir. Convenience blood samples were collected every 2 weeks during treatment. 007-TP in DBS was quantified using LC/MS and analysed using mixed-effects models. RESULTS: A total of 337 observations were available from 58 participants (78% male; 21% black; 22% Hispanic/Latino; 26% cirrhotic; 78% HIV-coinfected). The mean half-life of 007-TP in DBS was 142 h (95% CI 127-156) and concentrations increased by 7.3% (95% CI 2.2-12.6) for every 10% increase in between-visit adherence. Geometric mean (95% CI) 007-TP concentrations in DBS were 301 (247-368), 544 (462-639) and 647 (571-723) fmol/punch by adherence categories of ≤50%, >50 to ≤80%, and >80%. Adherence, time on therapy, increasing age and decreased estimated glomerular filtration rate were associated with higher 007-TP, whereas increased time since last dose, male sex, black race and higher BMI were associated with lower 007-TP. CONCLUSIONS: 007-TP has an extended half-life in DBS and concentrations increased with adherence. Further research is needed to examine additional factors that affect 007-TP and the clinical utility of this measure.

Use of Tenofovir Diphosphate Levels to Predict Viremia During the Postpartum Period in Women Living With Human Immunodeficiency Virus (HIV): A Nested Case-Control Study.

BACKGROUND: There are few data on the utility of tenofovir diphosphate (TFV-DP) in dried blood spots (DBSs) to predict future viral load (VL) in postpartum women with HIV on antiretroviral therapy (ART). METHODS: We conducted a nested case-control study within a trial of postpartum ART delivery strategies. Participants started ART containing tenofovir disoproxil fumarate (TDF) in pregnancy, were <10 weeks postpartum, and had a VL <400 copies/mL. VL and TFV-DP samples were taken every 3-6 months over 24 months. Cases had ≥1 VL ≥20 copies/mL; controls were randomly sampled from women with persistent viral suppression (VS; VL <20 copies/mL). Generalized estimating equations were used to calculate likelihood odds ratios (LORs) for future VL ≥20 copies/mL by TFV-DP concentration at the preceding visit. RESULTS: 61 cases and 20 controls contributed 365 DBS-VL pairs (median ART duration, 16 months). Sensitivity and specificity of TFV-DP <700 fmol/punch to detect future viremia were 62.9% (95% CI, 54.7-70.6%) and 89.7% (84.9-93.4%), respectively. Adjusting for age, ART duration, previous VL, and duration between the TFV-DP and VL measures, LORs of viremia for TFV-DP concentrations 350-699 and <350 fmol/punch versus TFV-DP ≥1850 fmol/punch were 3.5 (95% CI, 1.1-10.8; P = .033) and 12.9 (3.6-46.6; P < .0001), respectively. Including only samples taken during VS, the LOR of future viremia for TFV-DP concentration <350 fmol/punch versus TFV-DP ≥1850 fmol/punch was 9.5 (1.9-47.0). CONCLUSIONS: TFV-DP concentrations in DBSs were strongly associated with future viremia and appear useful to identify nonadherence and predict future elevated VL.

High residual inflammation despite HIV viral suppression: Lessons learned from real-time adherence monitoring among people with HIV in Africa.

BACKGROUND: Lower antiretroviral therapy (ART) adherence is associated with higher systemic inflammation in virally suppressed people with HIV (PWH); however, previous studies have mostly relied on subjective adherence measures and have not assessed this association by disease stage upon ART initiation. METHODS: In the Monitoring Early Treatment Adherence study, adherence was monitored electronically in real time among adult, treatment-naïve PWH in Uganda and South Africa who initiated tenofovir disoproxil fumarate/emtricitabine/efavirenz during early-stage (CD4 > 350 cells/µL) or late-stage (CD4 < 200 cells/µL) disease. Participants who achieved viral suppression (< 400 copies/mL) at 6 months and remained suppressed after 12 months were analysed. The association between average ART adherence and plasma concentrations of interleukin 6 (IL-6), soluble CD14 (sCD14) and D-dimer was evaluated using adjusted multivariable linear regression, stratified by disease stage. RESULTS: In all, 488 PWH (61% women, mean age 35 years) were included in the analysis. Median ART adherence overall was 87%. In adjusted models, every 10% increase in average adherence was associated with a 3.0% decrease in IL-6 [95% confidence interval (CI): -5.9 to -0.01, p = 0.05] at 12 months. This relationship was observed in PWH with both early-stage (5.9%, 95% CI: -10.1 to -1.6, p = 0.009) and late-stage disease (3.7%, 95% CI: -7.2 to -0.2, p = 0.039). No significant associations were found with sCD14 or D-dimer. CONCLUSIONS: Objective ART adherence measurement was inversely associated with systemic inflammation in PWH who achieved viral suppression after ART initiation in sub-Saharan Africa, with a greater association in those with early-stage HIV. This finding underscores the importance of ART adherence beyond establishing viral suppression.

Emtricitabine triphosphate in dried blood spots predicts future viremia in persons with HIV and identifies mismatch with self-reported adherence.

OBJECTIVE: Emtricitabine triphosphate (FTC-TP) in dried blood spots (DBS), a measure of short-term antiretroviral therapy (ART) adherence, is associated with viral suppression in persons with HIV (PWH). However, its ability to predict future viremia remains unknown. DESIGN: Prospective, observational cohort (up to three visits in 48 weeks). METHODS: PWH receiving TDF/FTC-based ART had DBS and HIV viral load obtained at routine clinical visits. FTC-TP in DBS was dichotomized into quantifiable vs. below the limit of quantification (BLQ). The adjusted odds ratio (aOR) of future viremia (≥20 copies/ml at next study visit) was estimated according to FTC-TP at the current visit. To assess for possible interactions, additional models adjusted for tenofovir diphosphate (TFV-DP) in DBS and 3-day self-reported adherence. RESULTS: Data from 433 PWH (677 paired DBS/HIV viral load samples) were analyzed. The aOR [95% confidence interval (CI)] for future viremia for BLQ vs. quantifiable FTC-TP was 3.4 (1.8--6.5; P = 0.0002). This diminished after adjusting for TFV-DP [aOR 1.9 (0.9--4.1); P = 0.090]. Among PWH reporting 100% 3-day adherence, the odds of future viremia were 6.0 times higher [(1.8--20.3); P = 0.001] when FTC-TP was BLQ vs. quantifiable. Among participants (n = 75) reporting less than 100% adherence, BLQ FTC-TP in DBS was not predictive of future viremia [aOR 1.3 (0.4--4.6); P = 0.96]. CONCLUSION: Nonquantifiable FTC-TP in DBS predicts future viremia and is particularly informative in PWH reporting perfect adherence. As point-of-care adherence measures become available, mismatches between objective and subjective measures, such as FTC-TP in DBS and self-report, could help clinicians identify individuals at an increased risk of future viremia.

Short Communication: A Descriptive Analysis of Dried Blood Spot Adherence Testing Among Ugandans with HIV Presenting with Cryptococcal Meningitis.

Early antiretroviral therapy (ART) initiation after cryptococcal meningitis increases mortality, and those unmasking cryptococcosis after <2 weeks of ART have higher mortality. However, it is unknown if those presenting as ART experienced are actually adherent to their ART. Unknowingly, restarting ART in persons, who have discontinued ART, may be a fatal iatrogenic error. To evaluate ART adherence in an exploratory analysis, we collected dried blood spots on 44 HIV-infected persons presenting with cryptococcal meningitis. We quantified tenofovir diphosphate (TFV-DP) and lamivudine (3TC) from dried blood spots. We quantified cumulative ART adherence over the preceding 6-8 weeks based on TFV-DP concentrations and adherence over the last few days based on 3TC concentrations. Of 22 ART experienced, 20 (91%) had quantifiable concentrations. Of 18 receiving tenofovir, 15 (83%) had TFV-DP consistent with drug intake of ≥4 doses/week or moderate adherence. With 3TC, 72% (18/22) had detectable levels consistent with adherence over the last 3 days before measurement. Only three ART-experienced subjects were alive and virally suppressed at 4 months (n = 2 on ART for <30 days; n = 1 with undetectable antiretrovirals). Surprisingly, of 22 who reported not receiving ART, 4 (18%) had quantifiable tenofovir. Most ART-experienced subjects were taking their ART with moderate to good adherence with the majority likely having viral resistance given generally at good ART levels, receipt of intensive adherence counseling, and lack of subsequent viral suppression. The World Health Organization (WHO) guidelines recommend adherence counseling with ART continuation and repeat viral loads in 1-3 months before switching to second-line ART. These recommendations are likely inappropriate in those with central nervous system infections given the additional possible harm of central nervous system immune reconstitution syndrome. Further study to evaluate continuation of ART regimens when presenting with cryptococcosis has benefit, with checking blood levels at presentation potentially being a helpful option. ClinicalTrials.gov Identifier: NCT01802385.

Intracellular Tenofovir-Diphosphate and Emtricitabine-Triphosphate in Dried Blood Spots Following Tenofovir Alafenamide: The TAF-DBS Study.

BACKGROUND: Tenofovir alafenamide (TAF), in combination with FTC, was recently approved for PrEP in the United States. The objective of this study was to assess the relationship between tenofovir-diphosphate (TFV-DP) and emtricitabine-triphosphate (FTC-TP) in dried blood spots (DBS) with adherence to TAF/FTC. METHODS: TAF-DBS was a randomized, crossover clinical study of TFV-DP in DBS, following directly observed dosing of 33%, 67%, or 100% of daily TAF (25 mg)/FTC (200 mg). Healthy volunteers were randomized to 2 different, 12-week dosing regimens, separated by a 12-week washout. DBS were collected weekly. TFV-DP and FTC-TP were extracted from two 7-mm punches and assayed with LC-MS/MS. RESULTS: Thirty-seven participants (17 female, 7 African American, and 6 Hispanic) were included. TFV-DP exhibited a mean half-life of 20.8 days (95% confidence interval: 19.3 to 21.3). The slope for TFV-DP versus dosing arm was 1.14 (90% confidence interval: 1.07 to 1.21). The mean (SD) TFV-DP after 12 weeks was 657 (186), 1451 (501), and 2381 (601) fmol/2 7-mm punches for the 33%, 67%, and 100% arms. The following adherence interpretations are proposed: <450 fmol/punches, <2 doses/wk; 450-949 fmol/punches, 2-3 doses/wk; 950-1799 fmol/punches, 4-6 doses/wk; and ≥1800 fmol/punches, 7 doses/wk. FTC-TP was quantifiable for 1 week after drug cessation in 50%, 92%, and 100% of participants in the 33%, 67%, and 100% arms, respectively. CONCLUSION: TFV-DP in DBS after TAF/FTC exhibited a long half-life and was linearly associated with dosing, similar to its predecessor tenofovir disoproxil fumarate. FTC-TP was quantifiable for up to 1 week after drug cessation. Together, these moieties provide complementary measures of cumulative adherence and recent dosing for TAF/FTC.

Inflammatory biomarkers prior to antiretroviral therapy as prognostic markers of 12-month mortality in South Africa and Uganda.

OBJECTIVE: The aim of this study was to determine the utility of biomarkers of immune activation, systemic inflammation and coagulopathy prior to antiretroviral therapy to predict mortality during the first year of antiretroviral therapy (ART) in sub-Saharan Africa. DESIGN: A prospective, observational cohort. METHODS: We measured soluble CD14, interleukin-6 and D-dimer in nonpregnant individuals initiating ART in South Africa and Uganda in the Measuring Early Treatment Adherence (META) Study. We used survival analysis methods to estimate their association with 12-month mortality, and fit receiver operator curves (ROC) to assess the prognostic value of each biomarker. RESULTS: Six-hundred and sixty individuals were enrolled and had pretreatment biomarkers measured. Approximately 60% were women, with a median CD4 cell count of 187 cells/µl [interquartile range (IQR) 111-425] and approximately half were enrolled each from South Africa and Uganda. We observed 34 deaths for a crude mortality of 5.3 deaths/100 person-years (py) (95% confidence interval 3.8-7.4), which ranged from 0/100 py to 13.7/100 py in the lowest and highest tertile of pretreatment sCD14, respectively. In Cox models, all three biomarkers were strongly predictive of the hazard of death (adjusted hazard ratio 3-6, all P < 0.01). In multivariable models including biomarkers, both pretreatment CD4 cell count and pretreatment viral load became borderline or nonsignificantly associated with mortality. The c-statistic for area under ROC was higher for all three biomarkers than for CD4 cell count (P < 0.01). CONCLUSION: Biomarkers of immune activation, systemic inflammation and coagulopathy prior to ART initiation are strongly predictive of early death on treatment after adjustment for CD4 cell count. Such biomarkers might serve as important prognostic indicators for patient triage in this population.

Timing of Antiretroviral Therapy and Systemic Inflammation in Sub-Saharan Africa: Results From the META Longitudinal Cohort Study.

Chronic inflammation predicts complications in persons with human immunodeficiency virus infection. We compared D-dimer, soluble CD14, and interleukin 6 levels before and 12 months after antiretroviral therapy (ART) initiation, among individuals starting ART during earlier-stage (CD4 T-cell count >350/µL) or late-stage disease (CD4 T-cell count <200/µL). Female sex, older age, viral load, and late-stage disease were associated with pre-ART biomarkers (n = 661; P < .05). However, there were no differences in biomarkers by disease stage after 12 months of ART (n = 438; P > .05), owing to loss from observation and greater declines in biomarkers in late-stage initiators (P < .001). Earlier initiation of ART is associated with decreased inflammation, but levels seem to converge between earlier and later initiators surviving to 12 months.

Incomplete ART adherence is associated with higher inflammation in individuals who achieved virologic suppression in the START study.

INTRODUCTION: Suboptimal ART adherence, despite HIV viral suppression, has been associated with chronic residual inflammation. Whether this association extends to individuals who initiate ART during early HIV infection remains unknown, which was the objective of this study. METHODS: Plasma levels of interleukin-6 (IL-6), high-sensitivity C-reactive protein, serum amyloid A protein (SAA), IL-27, soluble intercellular adhesion molecule-1, soluble vascular adhesion molecule-1, D-dimer and the CD4+/CD8+ T-cell ratio, were analysed at baseline and eight months after ART initiation in treatment-naïve participants with HIV and CD4+ T-cells >500 cells/mm3 enrolled in the immediate arm of START. Adherence was assessed by seven-day self-report. Multivariable linear regression was utilized to analyse the association between ART adherence and each biomarker at the eight-month visit in participants who achieved virologic suppression (<50 copies/mL). RESULTS: We evaluated 1627 participants (422 female) who achieved virologic suppression at the eight-month visit in the period between 2009 and 2013. Median (IQR) CD4+ T-cell count before ART was 651 (585, 769) cells/mm3 . Incomplete adherence was reported in 109 (7%) participants at the eight month visit. After adjusting for covariates, plasma IL-6 was 1.12 (95% CI, 1.00 to 1.26; p = 0.047) fold higher in participants reporting incomplete versus 100% adherence. A similar association for SAA was observed in an exploratory analysis (1.29 (95% CI 1.04 to 1.60); p = 0.02). No significant differences in other biomarkers were observed. CONCLUSIONS: Incomplete ART adherence was associated with higher IL-6 levels in individuals who achieved virologic suppression early after ART initiation in START. A potential similar association for SAA requires confirmation. These findings suggest a role for identifying strategies to maximize ART adherence even during virologic suppression. ClinicalTrials.gov number: NCT00867048.

Predictive Value of Tenofovir Diphosphate in Dried Blood Spots for Future Viremia in Persons Living With HIV.

BACKGROUND: Tenofovir diphosphate (TFV-DP) in dried blood spots (DBS) is associated with viral suppression in persons living with HIV (PLWH) taking tenofovir disoproxil fumarate (TDF). However, its value as a predictor of future viremia remained unknown. METHODS: Blood for plasma viral load (VL) and TFV-DP in DBS were collected (up to 3 visits within 48 weeks) in PLWH on TDF. TFV-DP cut points were selected using logistic prediction models maximizing the area under the receiver operation characteristic curve, and estimated adjusted odds ratio (aOR) of future viremia (≥20 copies/mL) were compared to the highest TFV-DP category. RESULTS: Among all 451 participants in the analysis, aOR of future viremia for participants with TFV-DP <800 and 800 to <1650 fmol/punch were 4.7 (95% CI, 2.6-8.7; P < .0001) and 2.1 (95% CI, 1.3-3.3; P = .002) versus ≥1650 fmol/punch, respectively. These remained significant for participants who were virologically suppressed at the time of the study visit (4.2; 95% CI, 1.5-12.0; P = .007 and 2.2; 95% CI, 1.2-4.0; P = .01). CONCLUSIONS: TFV-DP in DBS predicts future viremia in PLWH on TDF, even in those who are virologically suppressed. This highlights the utility of this biomarker to inform about adherence beyond VL. Clinical Trials Registration. NCT02012621.

Similar tenofovir hair concentrations in men and women after directly observed dosing of tenofovir disoproxil fumarate/emtricitabine: implications for preexposure prophylaxis adherence monitoring.

OBJECTIVES: Women likely require higher adherence than men to preexposure prophylaxis (PrEP) with tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) for similar efficacy. Pharmacologic metrics of adherence predict efficacy better than self-report, but expected drug levels (adherence benchmarks) must be established using directly observed therapy. We sought to evaluate whether tenofovir hair concentrations differ between women and men receiving directly observed TDF/FTC. METHODS: We assessed tenofovir hair concentrations in HIV-uninfected volunteers randomized to receive 100%, 67%, or 33% of daily dosing of TDF/FTC for 12 weeks (DOT-DBS, NCT02022657). Hair samples were collected at dosing weeks 4, 8, and 12 and every 3 weeks during a 12-week washout. Tenofovir concentrations in the proximal 1.5 cm of hair (representing ∼6 weeks of exposure) were analyzed using liquid chromatography/tandem mass spectrometry. Linear regression was used to model tenofovir hair concentrations in terms of sex, doses over the prior 6 weeks, and number of days since last dose. RESULTS: A total of 264 hair samples were analyzed from 23 female and 24 male participants. Female participants had similar tenofovir hair concentrations to men (estimated fold-difference 0.92, 95% CI 0.75-1.13, P = 0.43). The estimated fold-difference in tenofovir levels for female versus male participants did not appreciably change when age (0.93, 95% CI 0.76-1.15), weight (0.89, 95% CI 0.71-1.11), or race/ethnicity (0.95, 95% CI 0.77-1.17) were added to the model. CONCLUSION: Women and men have similar adherence benchmarks for tenofovir in hair samples. As pharmacokinetic metrics are increasingly used for PrEP monitoring, these findings provide guidance for assessing adherence via hair concentrations.

Adherence Measurements in HIV: New Advancements in Pharmacologic Methods and Real-Time Monitoring.

PURPOSE OF REVIEW: In this review, we present new developments in antiretroviral adherence, focusing on pharmacological measures and real-time adherence monitoring. In addition, new strategies on how to incorporate these new measures into research and clinical care are proposed. RECENT FINDINGS: Antiretroviral drug concentrations in hair and dried blood spots are two novel pharmacological measures of cumulative drug adherence and exposure that have been recently evaluated in HIV treatment and pre-exposure prophylaxis. Real-time adherence monitoring using electronic devices has also proven highly informative, feasible, and well accepted, offering the possibility for an immediate intervention when non-adherence is detected. Both approaches offer considerable advantages over traditional adherence measures in predicting efficacy. New methods to objectively monitor adherence in real-time and over long time periods have been developed. Further research is required to better understand how these measures can optimize adherence and, ultimately, improve clinical outcomes in HIV treatment and prevention.

Brief Report: Higher ART Adherence Is Associated With Lower Systemic Inflammation in Treatment-Naive Ugandans Who Achieve Virologic Suppression.

BACKGROUND: Residual systemic inflammation persists despite suppressive antiretroviral therapy (ART) and is associated with non-AIDS clinical outcomes. We aimed to evaluate the association between ART adherence and inflammation in Ugandans living with HIV who were predominantly receiving nevirapine-based ART with a thymidine analog backbone and were virologically suppressed by conventional assays. METHODS: Plasma concentrations of interleukin-6 (IL-6), D-dimer, soluble (s)CD14, sCD163, and the kynurenine/tryptophan ratio, in addition to CD8 T-cell activation, were measured at baseline and 6 months after ART initiation in treatment-naive adults who achieved an undetectable plasma HIV RNA (<400 copies/mL) at their 6-month visit. Adherence was measured through medication event monitoring system and calculated as the ratio of observed/prescribed device openings per participant. We fit adjusted linear regression models to estimate the association between ART adherence and the log-transformed plasma concentrations of inflammatory biomarkers. RESULTS: We evaluated 282 participants (median age, 35 years; 70% women). The median (interquartile range) adherence was 93% (84-98). In the adjusted analyses, for every 10% increase in average ART adherence, we found a 15% [P < 0.0001; 95% confidence interval (CI), -21.0 to -7.9], 11% (P = 0.017; 95% CI, -18.3 to -2.0), and 3% (P = 0.028; 95% CI, -5.0 to -0.3) decrease in IL-6, D-dimer, and sCD14, respectively. CONCLUSIONS: Higher ART adherence was associated with lower levels of biomarkers of inflammation, immune activation, and coagulopathy among Ugandans living with HIV who achieved viral suppression shortly after ART initiation. This suggests that ART adherence could have biological consequences beyond viral suppression. Whether ART adherence optimization in virologically suppressed individuals could reduce residual inflammation remains unknown.

The Impact of Statin and Angiotensin-Converting Enzyme Inhibitor/Angiotensin Receptor Blocker Therapy on Cognitive Function in Adults With Human Immunodeficiency Virus Infection.

BACKGROUND: Although statins, angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) are generally well tolerated, the impact of these therapies individually or in combination on the change in neurocognitive function in persons with human immunodeficiency virus infection is unknown. METHODS: The study included participants in the AIDS Clinical Trials Group Longitudinal Linked Randomized Trials cohort participants not receiving a statin or ACEI/ARB within 30 days of first neurologic assessment (baseline), with assessments by NPZ-3 (z score of averaged Trailmaking A and B tests and digit symbol test [DST]) from ≥2 measurements. Marginal structural models estimated the causal effect of statin or ACEI/ARB initiation on neurocognitive function; initial constant slope was assumed during the first year of treatment and a second constant slope thereafter. RESULTS: Of 3949 eligible participants, 16% started therapy with a statin, 11% with an ACEI/ARB, and 5% with both. Statin therapy had no significant effect on the composite NPZ-3 (primary outcome), Trailmaking B test, or DST. A small, nonsignificant positive effect on the Trailmaking A test was seen during year 1 (estimate, 0.088; 95% confidence interval, -.010 to .187; P = .08) and a small but significant negative effect (-0.033; -.058 to -.009; P = .007) in each subsequent year. ACEI/ARB therapy had a significant negative effect on the DST (-0.117; 95% confidence interval, -.217 to .016; P = .02) during year 1 but minimal effect in subsequent years or on other neurocognitive domains. CONCLUSIONS: In summary, although modest declines in neurocognitive performance were seen in single domains with statin or ACEI/ARB therapy, we did not find consistent evidence that statins or ACEI/ARB have an effect on global neurocognitive function. Future studies should focus on long-term neurocognitive effects.

Model Linking Plasma and Intracellular Tenofovir/Emtricitabine with Deoxynucleoside Triphosphates.

The coformulation of the nucleos(t)ide analogs (NA) tenofovir (TFV) disoproxil fumarate (TDF) and emtricitabine (FTC) is approved for HIV-infection treatment and prevention. Plasma TFV and FTC undergo complicated hybrid processes to form, accumulate, and retain as their active intracellular anabolites: TFV-diphosphate (TFV-DP) and FTC-triphosphate (FTC-TP). Such complexities manifest in nonlinear intracellular pharmacokinetics (PK). In target cells, TFV-DP/FTC-TP compete with endogenous deoxynucleoside triphosphates (dNTP) at the active site of HIV reverse transcriptase, underscoring the importance of analog:dNTP ratios for antiviral efficacy. However, NA such as TFV and FTC have the potential to disturb the dNTP pool, which could augment or reduce their efficacies. We conducted a pharmacokinetics-pharmacodynamics (PKPD) study among forty subjects receiving daily TDF/FTC (300 mg/200 mg) from the first-dose to pharmacological intracellular steady-state (30 days). TFV/FTC in plasma, TFV-DP/FTC-TP and dNTPs in peripheral blood mononuclear cells (PBMC) were quantified using validated LC/MS/MS methodologies. Concentration-time data were analyzed using nonlinear mixed effects modeling (NONMEM). Formations and the accumulation of intracellular TFV-DP/FTC-TP was driven by plasma TFV/FTC, which was described by a hybrid of first-order formation and saturation. An indirect response link model described the interplay between TFV-DP/FTC-TP and the dNTP pool change. The EC50 (interindividual variability, (%CV)) of TFV-DP and FTC-TP on the inhibition of deoxyadenosine triphosphate (dATP) and deoxycytidine triphosphate (dCTP) production were 1020 fmol/106 cells (130%) and 44.4 pmol/106 cells (82.5%), resulting in (90% prediction interval) 11% (0.45%, 53%) and 14% (2.6%, 35%) reductions. Model simulations of analog:dNTP molar ratios using IPERGAY dosing suggested that FTC significantly contributes to the protective effect of preexposure prophylaxis (PrEP). Simulation-based intracellular operational multiple dosing half-lives of TFV-DP and FTC-TP were 6.7 days and 33 hours. This model described the formation of intracellular TFV-DP/FTC-TP and the interaction with dNTPs, and can be used to simulate analog:dNTP time course for various dosing strategies.

Suboptimal Adherence to Combination Antiretroviral Therapy Is Associated With Higher Levels of Inflammation Despite HIV Suppression.

BACKGROUND: Human immunodeficiency virus (HIV)-infected individuals exhibit residual inflammation regardless of virologic suppression. We evaluated whether suboptimal adherence to combination antiretroviral therapy (cART) is associated with greater residual inflammation than optimal adherence, despite virologic suppression. METHODS: Longitudinal self-reported cART adherence data and serum concentrations of 24 biomarkers of inflammation and immune activation were measured at the same study visit in HIV RNA-suppressed (<50 copies/mL) HIV-infected men in the Multicenter AIDS Cohort Study from 1998 to 2009. Associations between dichotomized 6-month (<100% vs 100%) and categorized 4-day (<85%, 85%-99%, and 100%) cART adherence with biomarker concentrations were evaluated. RESULTS: A total of 912 men provided 2816 person-visits with documented plasma HIV RNA suppression. In adjusted models, person-visits at which <100% cART 6-month adherence was reported had higher concentrations of interleukin 2, 6, and 10, interferon γ, tumor necrosis factor α, and C-reactive protein than person-visits at which 100% cART adherence (P < .05) was reported. These same differences were observed in person-visits reporting <85% versus 100% 4-day cART adherence, but not in visits reporting 85%-99% versus 100% cART adherence. After adjustment for multiple comparisons, tumor necrosis factor α remained significantly higher (11% increase; P < .001) in person-visits at which <100% adherence was reported. CONCLUSIONS: Higher concentrations of inflammatory biomarkers were observed among HIV RNA-suppressed men who reported <100% cART adherence than among more adherent men. Residual HIV replication (ie, below the limit of detection), more likely among men with suboptimal adherence, is a plausible mechanism. Whether improving cART adherence could affect residual inflammation and associated morbidity and mortality rates should be investigated.

Intracellular Tenofovir and Emtricitabine Anabolites in Genital, Rectal, and Blood Compartments from First Dose to Steady State.

The pharmacokinetics (PK) of tenofovir-diphosphate (TFV-DP) and emtricitabine-triphosphate (FTC-TP), the active anabolites of tenofovir disoproxil fumarate (TDF), and emtricitabine (FTC) in blood, genital, and rectal compartments was determined in HIV-positive and seronegative adults who undertook a 60-day intensive PK study of daily TDF/FTC (plus efavirenz in HIV positives). Lymphocyte cell sorting, genital, and rectal sampling occurred once per subject, at staggered visits. Among 19 HIV-positive (3 female) and 21 seronegative (10 female) adults, TFV-DP in peripheral blood mononuclear cells (PBMC) accumulated 8.6-fold [95% confidence interval (CI): 7.2-10] from first-dose to steady-state concentration (Css) versus 1.7-fold (95% CI: 1.5-1.9) for FTC-TP. Css was reached in ∼11 and 3 days, respectively. Css values were similar between HIV-negative and HIV-positive individuals. Css TFV-DP in rectal mononuclear cells (1,450 fmol/106 cells, 898-2,340) was achieved in 5 days and was >10 times higher than PBMC (95 fmol/106 cells, 85-106), seminal cells (22 fmol/106 cells, 6-79), and cervical cells (111 fmol/106 cells, 64-194). FTC-TP Css was highest in PBMC (5.7 pmol/106 cells, 5.2-6.1) and cervical cells (7 pmol/106 cells, 2-19) versus rectal (0.8 pmol/106 cells, 0.6-1.1) and seminal cells (0.3 pmol/106 cells, 0.2-0.5). Genital drug concentrations on days 1-7 overlapped with estimated Css, but accumulation characteristics were based on limited data. TFV-DP and FTC-TP in cell sorted samples were highest and achieved most rapidly in CD14+ compared with CD4+, CD8+, and CD19+ cells. Together, these findings demonstrate cell-type and tissue-dependent cellular pharmacology, preferential accumulation of TFV-DP in rectal mononuclear cells, and rapid distribution into rectal and genital compartments.

Emtricitabine-Triphosphate in Dried Blood Spots as a Marker of Recent Dosing.

New objective measures of antiretroviral adherence are needed. We determined if emtricitabine triphosphate (FTC-TP) in dried blood spots (DBS) can be used as a marker of recent dosing with tenofovir disoproxil fumarate-emtricitabine (TDF-FTC). The half-life of FTC-TP was estimated in DBS samples obtained from an intensive pharmacokinetic (PK) study of coformulated TDF-FTC in HIV-negative and HIV-infected participants. The concordance of quantifiable FTC-TP in DBS with tenofovir (TFV)/FTC in plasma was evaluated by utilizing paired plasma-DBS samples from participants enrolled in 2 large preexposure prophylaxis (PrEP) open-label trials. The time to FTC-TP nondetectability after TDF-FTC dosing was evaluated utilizing DBS from HIV-negative participants enrolled in a directly observed therapy study of variable adherence to TDF-FTC. The mean (95% confidence interval [CI]) terminal half-life of FTC-TP in the PK study was 35 (23 to 47) h. A total of 143/163 (88%) samples obtained 0 to 48 h post-TDF-FTC dose had quantifiable FTC-TP in DBS, compared with 2/93 (2%) and 0/87 (0%) obtained >48 and >96 h postdose. In 746 paired plasma-DBS samples from 445 participants enrolled in PrEP trials, when both TFV/FTC in plasma were below the limit of quantification, FTC-TP was as well in 98.9% of the samples, and when either TFV or FTC in plasma was quantifiable, FTC-TP was as well in 90.5% of the samples. The half-life of FTC-TP in DBS is short relative to that of TFV-diphosphate (TFV-DP), making it a surrogate for TFV-FTC detection in plasma. FTC-TP can be quantified in DBS simultaneously with TFV-DP, which quantifies cumulative adherence to TDF-FTC. (The clinical trials discussed in this article have been registered at ClinicalTrials.gov under identifiers NCT01040091, NCT02022657, NCT00458393, NCT01772823, and NCT02012621.).

Application of an intracellular assay for determination of tenofovir-diphosphate and emtricitabine-triphosphate from erythrocytes using dried blood spots.

This communication describes the application of an existing intracellular methodology to the quantitation of tenofovir-diphosphate (TFV-DP) and emtricitabine-triphosphate (FTC-TP) from erythrocytes using dried blood spots (DBS). Concentrations were determined from a 3mm DBS punch extracted into a 70:30 methanol:water solution (lysed cellular matrix). This extraction solution was then subjected to a previously validated analytical procedure for lysed cellular matrix. Experiments for DBS validation used replicate samples from study participants to demonstrate acceptable reproducibility with spot volumes ranging from 10-50 µL and punch location either from the edge or center of the spot. Analysis of paired DBS with purified red blood cells showed that a 3mm DBS punch contained an average of 11.9 million cells for the observed hematocrit range of the participants (35-50%). Numerous stability tests were completed showing that whole blood in an EDTA vacutainer could sit for 24h at room temperature prior to spotting, and DBS could remain at room temperature for up to five days including shipment at ambient using 2-days delivery. DBS stability in storage was acceptable up to 18 months at -20°C or -80°C and DBS could undergo 4 Freeze/Thaw cycles. The described method was applied to HIV prophylaxis studies, demonstrating powerful associations with HIV acquisition through its ability to discriminate gradients of adherence.

Regional variation in HIV clinical trials participation in the United States.

OBJECTIVES: To ensure generalizability of clinical research results, it is important to enroll a heterogeneous population that is representative of the target clinical population. Earlier studies have found regional variation in participation in human immunodeficiency virus (HIV) clinical trials, with the lowest rates seen in the southern United States. Rates of new HIV diagnoses are highest in the South, highlighting the need for in-depth understanding of disparities in clinical trial participation. We evaluated whether regional variation in study participation remains, and describe factors that facilitate or prevent HIV clinical trial participation by region. METHODS: A one-time, anonymous, bilingual, self-administered survey was conducted among HIV-infected adults receiving HIV care at all 47 domestic AIDS Clinical Trials Group clinical research sites, with a goal of completing 50 surveys per site. χ(2) tests were used to evaluate differences in knowledge of and participation in HIV clinical trials by region, including Northeast, Midwest, South, and West regions. Multivariable logistic regression was used to estimate odds ratios and 95% confidence intervals (CIs) for the effect of region on knowledge of and participation in HIV clinical trials. RESULTS: Of 2263 completed surveys, 2125 were included in this analysis. The proportion of respondents in the South who reported knowledge of studies (66%) was significantly lower than in the Northeast (76%), Midwest (77%), and West (73%) (P = 0.001). Respondents in the South also were the least likely group to report ever having tried to or having participated in a research study (51%) compared with respondents in the Northeast (60%), Midwest (57%), and West (69%; P < 0.001). After adjusting for age, sex, education, race/ethnicity, tobacco use, and alcohol use, the odds ratio for knowledge of and participation in clinical trials for the Northeast (1.36; 95% CI 1.07-1.72) and West (1.85; 95% CI 1.39-2.45) remained significant compared with the South. African American respondents in the South were the most likely population group to report not understanding research studies (15%) as a reason for not participating, compared with the Northeast (9%), Midwest (8%), and West (6%; P < 0.001). CONCLUSIONS: Significant regional variations in knowledge of and participation in HIV clinical trials exist. Our results suggest that increasing awareness and understanding of research studies, particularly among African Americans in the South, may facilitate HIV clinical trial participation that is more representative of the HIV-infected population across the United States.