Development and validation of the first point-of-care assay to objectively monitor adherence to HIV treatment and prevention in real-time in routine settings

Drug Concentrations in Hair and Dried Blood Spots as Preexposure Prophylaxis Adherence Metrics During Pregnancy and Postpartum

We evaluated hair tenofovir (TFV) concentrations as an adherence metric for HIV preexposure prophylaxis during pregnancy and postpartum and compared hair levels with TFV-diphosphate levels in dried blood spots (DBSs). Overall 152 hair samples from 102 women and 36 hair-DBS paired samples from 29 women were collected from a subset of women in a cluster-randomized trial. Having a partner with HIV was associated with higher hair TFV levels (P < .001). Hair TFV concentrations were strongly correlated with DBS TFV-diphosphate levels (r = 0.76, P < .001), indicating hair as a promising cumulative adherence metric for perinatal preexposure prophylaxis assessment.

Integrated PrEP and STI Services for Transgender Women in Uganda: Qualitative Findings from a Randomized Trial

Tenofovir alafenamide fumarate (F/TAF) pre-exposure prophylaxis (PrEP) is understudied in sub-Saharan Africa. The Tandika PrEP study was a randomized trial that evaluated same-day F/TAF initiation, the impact of drug-level feedback on PrEP adherence, and integrated PrEP and sexually transmitted infection (STI) services for HIV-negative transgender women (TGW) in Uganda (NCT04491422). From April 2022-February 2023, a qualitative sub-study of 30 in-depth interviews explored (1) perspectives on same-day initiation of F/TAF PrEP, (2) experiences of urine tenofovir testing and drug-level feedback, and (3) descriptions of self-collection of samples for STI testing. Qualitative data were analyzed using an inductive content analytic approach. Integrated PrEP/STI services were valued by TGW because the convenience of urine testing motivated adherence and allowed for tenofovir and STI detection. (1) Preferred characteristics: F/TAF-based PrEP was easy to take and not readily identifiable as an HIV-related medication, resulting in less stigma than the better-known tenofovir disoproxil fumarate (F/TDF). Weight gain associated with F/TAF use was viewed positively by TGW as a symbol of health and prosperity in African settings. (2) Adherence motivation: PrEP adherence was motivated by a desire not to disappoint healthcare workers; TGW reciprocated adherence support and drug-level feedback by taking PrEP. (3) Facilitating adherence and STI care: Urine testing enhanced STI detection and treatment. Utilization of urine for tenofovir and STI testing motivated the uptake of HIV/STI care, emphasizing the importance of integrated PrEP and STI services. Integrating PrEP/STI services into differentiated delivery models could increase prevention uptake in this vulnerable population.

Point-of-care urine tenofovir test predicts future HIV preexposure prophylaxis discontinuation among young users

BACKGROUND

Young men who have sex with men and transgender women (YMSM/TGW) have disproportionately high HIV incidence and lower preexposure prophylaxis (PrEP) adherence. Point-of-care (POC) urine tenofovir (TFV) rapid assay (UTRA) testing permits real-time monitoring for nonadherence within clinical settings. We performed UTRA testing among PrEP users to examine the relationship between low PrEP adherence and future PrEP discontinuation, and the accuracy of POC testing compared to gold-standard liquid chromatography tandem mass spectrometry (LC/MS/MS).

METHODS

YMSM/TGW participants ( n  = 100) were recruited during a daily PrEP visit. Logistic regression models analyzed the relationship between the primary predictor of urine POC assay results (cutoff 1,500 ng/ml) and the primary outcome of PrEP discontinuation, defined as no PrEP follow-up or prescription within 120 days.

RESULTS

Overall, 19% of participants had low urine TFV and 21% discontinued PrEP, while 11% of participants self-reported low PrEP adherence (<4 pills per week), which was only 43% sensitive/84% specific in predicting low TFV levels and was not associated with PrEP discontinuation. Low urine TFV level predicted PrEP discontinuation [adjusted odds ratio (AOR) 6.1; 95% confidence interval (CI): 1.4-11; P  = 0.005] and was 71% sensitive/90% specific for discontinuation after 120 days. Compared to LC/MS/MS, UTRA testing had a 98% positive and 100% negative predictive value.

CONCLUSIONS

In a sample of YMSM/TGW on daily PrEP, POC UTRA testing predicted PrEP discontinuation more accurately than self-reported adherence, with high predictive values compared to LC/MS/MS. UTRA testing may be a clinical tool for directing preventive interventions towards those likelier to discontinue PrEP despite ongoing HIV vulnerability.

Impact of a point-of-care urine tenofovir assay on adherence to HIV pre-exposure prophylaxis among women in Kenya: a randomised pilot trial

BACKGROUND

Adherence challenges with oral tenofovir-based pre-exposure prophylaxis (PrEP) are common. We developed a point-of-care assay to objectively assess tenofovir in urine and conducted a pilot trial examining the impact of counselling informed by use of this urine assay on long-term PrEP adherence.

METHODS

This randomised trial enrolled women not in serodiscordant partnerships 3 months after PrEP initiation at the Kenya Medical Research Institute to compare standard-of-care adherence counselling versus counselling informed by the urine assay (urine-test counselling group) every 3 months for 12 months. In the standard of care group, urine samples were stored and tested at study end without participant feedback. Here we report the adherence primary outcome of hair concentrations of tenofovir at 12 months as a long-term metric (undetectable levels defined long-term non-adherence), as well as urine concentrations of tenofovir at each visit as a short-term adherence metric and acceptability of the assay assessed by quantitative surveys. Data were analysed by randomisation group. This completed trial was registered with ClinicalTrials.gov (NCT03935464).

FINDINGS

From March 17, 2021 to Jan 18, 2022 we enrolled 49 women in the urine-test counselling group and 51 in the standard of care group; retention was 86 (86%) of 100. Nine (21%) of 42 in the urine-test counselling group had hair samples at 12 months with tenofovir concentrations below the limit of quantification compared with 15 (37%) of 41 in the standard of care group. The relative odds of long-term non-adherence in the standard of care group compared with urine-test counselling were 3·53 (95% CI 1·03-12·03; p=0·044). Pre-intervention, urine tenofovir was detectable in 65% in the urine-test counselling group and 71% in the standard of care group (p=0·68). At 12 months, 31 (72%) of 43 in the intervention group had detectable urine tenofovir compared with 19 (45%) of 42 in the standard of care group (p=0·0015). 40 (93%) of 43 participants liked the test very much and only one disliked the test. One participant in the standard of care group was withdrawn at the 6-month visit due to HIV seroconversion.

INTERPRETATION

A low-cost urine tenofovir assay to inform PrEP counselling resulted in improvement in both short-term and long-term metrics of adherence. This urine tenofovir assay could help to improve long-term PrEP adherence.

FUNDING

National Institute of Allergy and Infectious Diseases and National Institutes of Health.

Tenofovir, emtricitabine, lamivudine and dolutegravir concentrations in plasma and urine following drug intake cessation in a randomized controlled directly observed pharmacokinetic trial to aid point-of-care testing

BACKGROUND

Poor adherence to ART and pre-exposure prophylaxis (PrEP) can impact patient and public health. Point-of-care testing (POCT) may aid monitoring and adherence interventions.

OBJECTIVES

We report the pharmacokinetics of tenofovir [dosed as tenofovir disoproxil (TDF) and tenofovir alafenamide (TAF)], emtricitabine (FTC), lamivudine (3TC) and dolutegravir (DTG) in plasma and urine following drug cessation to evaluate adherence targets in urine for POCT.

METHODS

Subjects were randomized (1:1) to receive DTG/FTC/TAF or DTG/3TC/TDF for 15 days. Plasma and spot urine were collected on Day 15 (0-336 h post final dose). Drug concentrations were quantified using LC-MS, and non-linear mixed-effects models applied to determine drug disposition between matrices and relationship with relevant plasma [dolutegravir protein-adjusted 90% inhibitory concentration (PA-IC90 = 64 ng/mL) and minimum effective concentration (MEC = 324 ng/mL)] and urinary thresholds [tenofovir disoproxil fumarate 1500 ng/mL].

RESULTS

Of 30 individuals enrolled, 29 were included (72% female at birth, 90% Caucasian). Median (range) predicted time to plasma dolutegravir PA-IC90 and MEC were 83.5 (41.0-152) and 49.0 h (23.7-78.9), corresponding to geometric mean (90%) urine concentrations of 5.42 (4.37-6.46) and 27.4 ng/mL (22.1-32.7). Tenofovir in urine reached 1500 ng/mL by 101 h (58.6-205) with an equivalent plasma concentration of 6.20 ng/mL (4.21-8.18).

CONCLUSIONS

These data support use of a urinary tenofovir threshold of <1500 ng/mL (tenofovir disoproxil fumarate-based regimens) as a marker of three or more missed doses for a POCT platform. However, due to low dolutegravir concentrations in urine, POCT would be limited to a readout of recent dolutegravir intake (one missed dose).

Applying the Effective Programme Coverage framework to assess gaps in HIV prevention programmes for female sex workers and men who have sex with men in Nairobi, Kenya: findings from an expanded Polling Booth Survey

INTRODUCTION

Measuring the coverage of HIV prevention services for key populations (KPs) has consistently been a challenge for national HIV programmes. The current frameworks and measurement methods lack emphasis on effective coverage, occur infrequently, lack timeliness and limit the participation of KPs. The Effective Programme Coverage framework, which utilizes a programme science approach, provides an opportunity to assess gaps in various coverage domains and explore the underlying reasons for these gaps, in order to develop targeted solutions. We have demonstrated the application of this framework in partnership with the KP community in Nairobi, Kenya, using an expanded Polling Booth Survey (ePBS) method.

METHODS

Data were collected between April and May 2023 among female sex workers (FSWs) and men who have sex with men (MSM) using (a) PBS, (b) bio-behavioural survey and (c) focus group discussions. Data collection and analysis involved both KP community and non-community researchers. Descriptive analysis was performed, and proportions were used to assess the programme coverage gaps. The data were weighted to account for the sampling design and unequal selection probabilities. Thematic analysis was conducted on the qualitative data.

RESULTS

The condom programme for FSW and MSM had low availability (60.2% and 50.9%), contact (68.8% and 65.9%) and utilization (52.1% and 43.9%) coverages. The pre-exposure prophylaxis (PrEP) programme had very low utilization coverage for FSW and MSM (4.4% and 2.8%), while antiretroviral therapy utilization coverage was higher (86.6% and 87.7%). Reasons for coverage gaps included a low peer educator-to-peer ratio, longer distance to the clinics, shortage of free condoms supplied by the government, experienced and anticipated side effects related to PrEP, and stigma and discrimination experienced in the facilities.

CONCLUSIONS

The Effective Programme Coverage framework allows programmes to assess coverage gaps and develop solutions and a research agenda targeted at specific domains of coverage with large gaps. The ePBS method works well in collecting data to understand coverage gaps rapidly and allows for the engagement of the KP community.

Assessing Outcomes in HIV Prevention and Treatment Programs With Female Sex Workers and Men Who Have Sex With Men: Expanded Polling Booth Survey Protocol

BACKGROUND

Assessing HIV outcomes in key population prevention programs is a crucial component of the program cycle, as it facilitates improved planning and monitoring of anticipated results. The Joint United Nations Programme on HIV and AIDS recommends using simple, rapid methods to routinely measure granular and differentiated program outcomes for key populations. Following a program science approach, Partners for Health and Development in Africa, in partnership with the Nairobi County Government and the University of Manitoba, aims to conduct an outcome assessment using a novel, expanded polling booth survey (ePBS) method with female sex workers and men who have sex with men in Nairobi County, Kenya.

OBJECTIVE

This study aims to (1) estimate the incidence and prevalence of HIV; (2) assess biomedical, behavioral, and structural outcomes; and (3) understand barriers contributing to gaps in access and use of available prevention and treatment services among female sex workers and men who have sex with men in Nairobi.

METHODS

The novel ePBS approach employs complementary data collection methods, expanding upon the traditional polling booth survey (PBS) method by incorporating additional quantitative, qualitative, and biological data collection components and an improved sampling methodology. Quantitative methods will include (1) PBS, a group interview method in which individuals provide responses through a ballot box in an unlinked and anonymous way, and (2) a behavioral and biological survey (BBS), including a face-to-face individual interview and collection of linked biological samples. Qualitative methods will include focus group discussions. The ePBS study uses a 2-stage, population- and location-based random sampling approach involving the random selection of locations from which random participants are selected at a predetermined time on a randomly selected day. PBS data will be analyzed at the group level, and BBS data will be analyzed at an individual level. Qualitative data will be analyzed thematically.

RESULTS

Data were collected from April to May 2023. The study has enrolled 759 female sex workers (response rate: 759/769, 98.6%) and 398 men who have sex with men (response rate: 398/420, 94.7%). Data cleaning and analyses are ongoing, with a focus on assessing gaps in program coverage and inequities in program outcomes.

CONCLUSIONS

The study will generate valuable HIV outcome data to inform program improvement and policy development for Nairobi County's key population HIV prevention program. This study served as a pilot for the novel ePBS method, which combines PBS, BBS, and focus group discussions to enhance its programmatic utility. The ePBS method holds the potential to fill an acknowledged gap for a rapid, low-cost, and simple method to routinely measure HIV outcomes within programs and inform incremental program improvements through embedded learning processes.

Point-of-care urine tenofovir monitoring of adherence to drive interventions for HIV treatment and prevention

INTRODUCTION

Although effective antiretroviral and pre-exposure prophylaxis/PrEP regimens are available globally, adherence challenges persist. Objective measures of adherence can both measure adherence accurately and can be used to drive interventions. The first point-of-care pharmacologic adherence measure, urine tenofovir testing using a lateral flow assay, is now available.

AREAS COVERED

This review examines the ability of pharmacologic metrics of adherence to predict HIV and PrEP clinical outcomes and the past use of pharmacologic metrics of adherence as tools to drive adherence interventions. The success of preliminary studies using point-of-care adherence metrics to guide interventions is then discussed.

EXPERT OPINION

Large randomized clinical trials are now needed to test the impact of point-of-care adherence interventions on HIV and PrEP clinical outcomes, given promising results of the pilot studies summarized here. Hybrid implementation-effectiveness studies will be needed to examine optimal approaches to incorporating point-of-care testing into routine clinical care delivery, including in guiding resistance testing, adherence counseling, and delivery of other evidence-based adherence interventions. Given the ability of point-of-care tenofovir testing to be implemented in settings where viral load testing is not available, and at more frequent intervals due to its low cost, urine-based tenofovir assays have the potential to be highly scalable in diverse clinical settings.

Comparing a point-of-care urine tenofovir lateral flow assay to self-reported adherence and their associations with viral load suppression among adults on antiretroviral therapy

BACKGROUND

Point-of-care (POC) lateral flow assays (LFA) to detect tenofovir (TFV) in urine have been developed to measure short-term ART adherence. Limited data exist from people living with HIV in routine care.

METHODS

Adults on TFV-containing regimens, having a routine viral load (VL) at an HIV clinic in Cape Town, South Africa were enrolled in a cross-sectional study. Patients recalled missed ART doses in the past three and 7 days and urine was tested using a POC TFV LFA. VL on the day was abstracted from medical records.

RESULTS

Among 314 participants, 293 (93%) had VL <1000 copies/mL, 20 (6%) had no TFV detected and 24 (8%) reported ≥1 missed dose in the past 3 days. Agreement between VL ≥1000 and undetectable TFV was higher compared to 3-day recall of ≥1 missed dose (Kappa 0.504 vs. 0.163, p = 0.015). The AUC to detect VL ≥1000 was 0.747 (95% CI 0.637-0.856) for undetectable TFV. This was statistically significantly better than for 7-day recall (0.571 95% CI 0.476-0.666, p = 0.040) but not for 3-day recall (0.587 95% CI 0.492-0.681, p = 0.071) of ≥1 missed dose.

CONCLUSION

In this largely virally suppressed cohort, TFV in urine had better agreement with VL than self-reported adherence and was a better predictor of viraemia on two of three self-report measures. Used in combination with VL, the POC urine TFV LFA could flag patients with viraemia in the presence of ART. Further research is needed to understand the potential application in different populations on ART, including pregnant women.

The effect of daily oral PrEP use during pregnancy on bone mineral density among adolescent girls and young women in Uganda

Introduction

Oral pre-exposure prophylaxis (PrEP) is recommended during pregnancy for at-risk cisgender women. Pregnancy is known to impede bone growth and tenofovir-based PrEP may also yield detrimental changes to bone health. Thus, we evaluated the effect of PrEP use during pregnancy on bone mineral density (BMD).

Methods

We used data from a cohort of women who were sexually active, HIV-negative, ages 16-25 years, initiating DMPA or choosing condoms for contraception and enrolled in the Kampala Women's Bone Study. Women were followed quarterly with rapid testing for HIV and pregnancy, PrEP dispensation, and adherence counseling. Those who became pregnant were counseled on PrEP use during pregnancy per national guidelines. BMD of the neck of the hip, total hip, and lumbar spine was measured using dual-energy x-ray absorptiometry at baseline and annually. We compared the mean percent change in BMD from baseline to month 24.

Results

Among 499 women enrolled in the study, 105 pregnancies occurred in 90 women. At enrollment, the median age was 20 years (IQR: 19-21) and 89% initiated PrEP. During pregnancy, 67% of women continued using PrEP and PrEP was dispensed in 64% of visits. BMD declined significantly in women using PrEP during pregnancy compared to women who were not pregnant nor used PrEP: relative BMD change was -2.26% (95% CI: -4.63 to 0.11, p = 0.06) in the femoral neck, -2.57% (95% CI: -4.48 to -0.66, p = 0.01) in total hip, -3.06% (95% CI: -5.49 to -0.63, p = 0.001) lumbar spine. There was no significant difference in BMD loss when comparing PrEP-exposed pregnant women to pregnant women who never used PrEP. Women who became pregnant were less likely to continue PrEP at subsequent study visits than women who did not become pregnant (adjOR: 0.25, 95% CI: 0.16-0.37, p < 0.001). Based on pill counts, there was a 62% reduction in the odds of high PrEP adherence during pregnancy (adjOR = 0.38, 95% CI: 0.27-0.58, p < 0.001).

Conclusion

Women who used PrEP during pregnancy experienced a similar reduction in BMD as pregnant women with no PrEP exposure, indicating that BMD loss in PrEP-using pregnant women is largely driven by pregnancy and not PrEP.

Accuracy of Provider Predictions of Viral Suppression Among Adolescents and Young Adults With HIV in an HIV Clinical Program

BACKGROUND

Providers caring for adolescents and young adults with HIV (AYA-HIV) mostly base their adherence counseling during clinical encounters on clinical judgment and expectations of patients' medication adherence. There is currently no data on provider predictions of viral suppression for AYA-HIV. We aimed to assess the accuracy of provider predictions of patients' viral suppression status compared to viral load results.

METHODS

Providers caring for AYA-HIV were asked to predict the likelihood of viral suppression of patients before a clinical encounter and give reasons for their predictions. Provider predictions were compared to actual viral load measurements of patients. Patient data were abstracted from electronic health records. The final analysis included 9 providers, 28 patients, and 34 observations of paired provider predictions and viral load results.

RESULTS

Provider prediction accuracy of viral suppression was low (59%, Cohen's Kappa = 0.16). Provider predictions of lack of viral suppression were based on nonadherence to medications, new patient status, or structural vulnerabilities (e.g., unstable housing). Anticipated viral suppression was based on medication adherence, history of viral suppression, and the presence of family or other social forms of support.

CONCLUSIONS

Providers have difficulty accurately predicting viral suppression among AYA-HIV and may base their counseling on incorrect assumptions. Rapid point-of-care viral load testing may provide opportunities to improve counseling provided during the clinical encounter.

Feasibility, Acceptability and Appropriateness of MedViewer: A Novel Hair-Based Antiretroviral Real-Time Clinical Monitoring Tool Providing Adherence Feedback to Patients and Their Providers

Antiretroviral therapy (ART) adherence is key to achieving viral load suppression and ending the HIV epidemic but monitoring and supporting adherence using current interventions is challenging. We assessed the feasibility, acceptability and appropriateness of MedViewer (MV), a novel intervention that provides real-time adherence feedback for patients and providers using infra-red matrix-assisted laser desorption electrospray ionization (IR-MALDESI) for mass spectrometry imaging of daily ART concentrations in patients' hair. We used mixed methods to feasibility test MV at a busy Infectious Diseases (ID) clinic, enrolling 16 providers and 36 patients. Providers underwent standardized training; patients and providers watched an 8-min informational video about MV. We collected patient and provider data at baseline and within 24 h of clinic visits and, with patients, approximately 1 month after clinic visits. MedViewer was feasible, liked by patients and providers, and perceived to help facilitate adherence conversations and motivate patients to improve adherence. Trial Registration: NCT04232540.

Urine point-of-care tenofovir test demonstrates strong predictive clinical and research utility

BACKGROUND

Preexposure prophylaxis (PrEP) significantly reduces HIV infection risk but is dependent on adherence. Available approaches to measuring adherence have limitations related to accuracy, cost, practicality, and timeliness. This study compared the performance of two methods implementable in clinics and research studies [interview and urine point of care (POC) assay] to the gold-standard for measuring recent and longer term adherence in dried blood spots (DBS).

METHODS

Participants were recruited from RADAR, a cohort study of young MSM, or via online advertisements. At 3 monthly visits, an interviewer administered 7-day timeline follow-back (TLFB) questionnaire, DBS samples were tested for tenofovir-diphosphate (TFV-DP) to estimate average dosing over the prior month and emtricitabine-triphosphate (FTC-TP) to assess recent dosing (past 2-3 days), and a urine POC TFV test to qualitatively assess recent adherence (past 4 days).

RESULTS

Eighty-three PrEP users contributed 163 observations. At visit 1, self-reported adherence was 86% (4+ doses in last 7 days), versus urine TFV (74%), DBS FTC-TP (76%), and DBS TFV-DP (69%). The objective measures of short-term adherence performed similarly well in predicting longer term adherence. In multivariable logistic regression analyses, the urine assay was a significant predictor of DBS TFV-DP (adjusted OR = 19.4, P  < 0.0001); self-report did not add significantly.

CONCLUSION

The urine POC TFV assay had excellent predictive values for adherence and self-report did not add significantly to prediction. The POC assay provides results in several minutes to enable same-visit counseling, requires no specialized training, and is projected to be low-cost.

Perspectives of people living with HIV and health workers about a point-of-care adherence assay: a qualitative study on acceptability

Current antiretroviral therapy (ART) adherence monitoring is premised on patients' self-reported adherence behaviour (prone to recall error) and verified by blood viral load measurement (which can delay results). A newly developed Urine Tenofovir Rapid Assay (UTRA) assesses tenofovir in urine at point-of-care and is a novel tool to test and immediately respond to adherence levels of people living with HIV (PLHIV). We explored PLHIV and health workers' initial perceptions about integrating the UTRA into routine medical care for adherence support. We conducted a series of once-off in-depth qualitative interviews with PLHIV (n = 25) and health workers (n = 5) at a primary care health facility in Cape Town, South Africa. Data analysis involved descriptive summaries of key emergent themes with illustrative case examples. We applied a deductive, outcomes-driven analytic approach to the summaries using the Implementation Outcomes Framework proffered by Proctor et al. (2011). The three relevant concepts from this framework that guided our evaluation were: acceptability, appropriateness, and feasibility. We found positive perceptions about the UTRA from many PLHIV and health worker participants. Many PLHIV reported that the immediate results offered by the UTRA could enable them to have constructive discussions with health workers on how to resolve adherence challenges in real-time. Few PLHIV reported concerns that drinking alcohol could affect their UTRA results. Many health workers reported that the UTRA could help them identify patients at risk of treatment failure and immediately intervene through counselling, though some relayed that they would support the UTRA's implementation if more staff members could be added in their busy facility. Overall, these findings show that the UTRA was widely perceived to be acceptable and actionable by many PLHIV and health workers in the study.

Diagnostic accuracy of a point-of-care urine tenofovir assay, and associations with HIV viraemia and drug resistance among people receiving dolutegravir and efavirenz-based antiretroviral therapy

INTRODUCTION

Novel point-of-care assays which measure urine tenofovir (TFV) concentrations may have a role in improving adherence monitoring for people living with HIV (PLHIV) receiving antiretroviral therapy (ART). However, further studies of their diagnostic accuracy, and whether results are associated with viraemia and drug resistance, are needed to guide their use, particularly in the context of the global dolutegravir rollout.

METHODS

We conducted a cross-sectional evaluation among PLHIV receiving first-line ART containing tenofovir disoproxil fumarate at enrolment into a randomized trial in two South African public sector clinics. We calculated the diagnostic accuracy of the Abbott point-of-care immunoassay to detect urine TFV compared to liquid chromatography-tandem mass spectrometry (LC-MS/MS). We evaluated the association between point-of-care urine TFV results and self-reported adherence, viraemia ≥1000 copies/ml and HIV drug resistance, among people receiving either efavirenz or dolutegravir-based ART.

RESULTS

Between August 2020 and March 2022, we enrolled 124 participants. The median age was 39 (IQR 34-45) years, 55% were women, 74 (59.7%) were receiving efavirenz and 50 (40.3%) dolutegravir. The sensitivity and specificity of the immunoassay to detect urine TFV ≥1500 ng/ml compared to LC-MS/MS were 96.1% (95% CI 90.0-98.8) and 95.2% (75.3-100.0), respectively. Urine TFV results were associated with short (p<0.001) and medium-term (p = 0.036) self-reported adherence. Overall, 44/124 (35.5%) had viraemia, which was associated with undetectable TFV in those receiving efavirenz (OR 6.01, 1.27-39.0, p = 0.014) and dolutegravir (OR 25.7, 4.20-294.8, p<0.001). However, in those with viraemia while receiving efavirenz, 8/27 (29.6%) had undetectable urine TFV, compared to 11/17 (64.7%) of those receiving dolutegravir. Drug resistance was detected in 23/27 (85.2%) of those receiving efavirenz and only 1/16 (6.3%) of those receiving dolutegravir. There was no association between urine TFV results and drug resistance.

CONCLUSIONS

Among PLHIV receiving ART, a rapid urine TFV immunoassay can be used to accurately monitor urine TFV levels compared to the gold standard of LC-MS/MS. Undetectable point-of-care urine TFV results were associated with viraemia, particularly among people receiving dolutegravir.

TRIAL REGISTRATION

Pan-African Clinical Trials Registry: PACTR202001785886049.

Contingency Management for Integrated Harm Reduction Among Men Who Have Sex with Men Who Use Methamphetamine in Los Angeles: A Pilot Assessment

Methamphetamine (MA) use is associated with HIV transmission among men who have sex with men (MSM) and lapses in medication adherence. Contingency Management (CM) is effective in reducing MA use, but studies of CM to support adherence to HIV prevention or treatment are limited. We conducted a pilot trial of a CM intervention to reduce MA use and improve PrEP/ART adherence among MSM prescribed a tenofovir (TFV)-based regimen for HIV prevention or treatment. Participants were randomly assigned to receive escalating incentives for either MA abstinence or TFV adherence (based on point-of-care urine testing), and to a monitoring schedule of either 2 or 3 visits/week for 4 weeks. 19 MSM were randomized to either CM for MA use or CM for PrEP/ART adherence (median age: 38; IQR: 28-46) and 15 were living with HIV. Participants attended 95.7% (67/70) of scheduled visits in the 2x/week arm and 74.8% (74/99) in the 3x/week arm. TFV adherence was higher among participants in the TFV adherence arm with 93.5% (n = 72/77) of urine samples positive for TFV, compared to 76.6% (n = 49/64) in the MA abstinence arm (p = 0.007). Participants in the MA abstinence arm had more urine samples negative for MA metabolites (20.3%, n = 13/64) than those receiving CM for TFV adherence (6.5%, n = 5/77; p = 0.021). A CM model for MA abstinence and PrEP/ART adherence using twice-weekly visits and urine testing for MA and TFV for MSM who use MA is feasible and potentially effective as an integrated harm reduction strategy.

Point-of-care urine tenofovir testing to predict HIV drug resistance among individuals with virologic failure

OBJECTIVE

We sought to evaluate the utility of a point-of-care (POC) urine tenofovir (TFV) assay, developed to objectively assess adherence, to predict HIV drug resistance (HIVDR) in people failing first-line antiretroviral therapy (ART).

DESIGN

We retrospectively analyzed TFV levels as a biomarker of adherence in urine specimens collected during a clinical trial that enrolled adults with virologic failure on first-line ART in Uganda and South Africa.

METHODS

Urine specimens were analyzed from participants on TFV-containing regimens who had a viral load >1000 copies/ml and paired genotypic resistance test (GRT) results. We assessed recent ART TFV adherence with a qualitative POC lateral flow urine assay with a cut-off value of 1500 ng/ml. We then calculated performance characteristics of the POC urine TFV assay to predict HIVDR, defined as intermediate or high-level resistance to any component of the current ART regimen.

RESULTS

Urine specimens with paired plasma GRT results were available from 283 participants. The most common ART regimen during study conduct was emtricitabine, tenofovir disoproxil fumarate, and efavirenz. The overall prevalence of HIVDR was 86% ( n = 243/283). Of those with TFV detected on the POC assay, 91% ( n  = 204/224) had HIVDR, vs. only 66% ( n  = 39/59) among those with no TFV detected ( P- value < 0.001). Positive and negative predictive values of the assay to predict HIVDR were 91% and 34%, respectively.

CONCLUSIONS

In populations with a high prevalence of HIVDR, the POC urine TFV assay can provide a low-cost, rapid method to guide requirements for confirmatory resistance testing and inform the need for regimen change.

The future of HIV pre-exposure prophylaxis adherence: reducing barriers and increasing opportunities

The effectiveness of HIV pre-exposure prophylaxis (PrEP) hinges on adherence, which has been restricted by multifaceted barriers. Uptake of PrEP has been impeded by poor access resulting from high costs, provider uncertainty, discrimination, stigma, and poor understanding within the health-care community and the public of who can benefit from PrEP. Other important barriers to adherence and persistence over time relate to individuals (eg, depression) and their community, partners, and family (eg, poor support), and their effects vary substantially with each person, population, and setting. Despite these challenges, key opportunities for improving PrEP adherence exist, including novel delivery systems, tailored individual interventions, mobile health and digital health interventions, and long-acting formulations. Objective monitoring strategies will help to improve adherence interventions and alignment of PrEP use with the need for HIV prevention (ie, prevention-effective adherence). The future of PrEP adherence lies in person-centred approaches to service delivery that meet the needs of individuals while creating supportive environments and facilitating health-care access and delivery.

Contingency Management and Pre-Exposure Prophylaxis Adherence Support Services (CoMPASS): A hybrid type 1 effectiveness-implementation study to promote HIV risk reduction among people who inject drugs

BACKGROUND

HIV disproportionally affects persons who inject drugs (PWID), but engagement with HIV pre-exposure prophylaxis (PrEP) is low. We describe the rationale and study design for a new study, "Contingency Management and Pre-Exposure Prophylaxis (PrEP) Adherence Support Services (CoMPASS)," a hybrid type 1 effectiveness-implementation trial to promote HIV risk reduction among PWID.

METHODS

In four community-based programs in the northeastern United States, PrEP-eligible PWID (target n = 526) are randomized to treatment as usual or Contingency Management (CM) and, as indicated, stepped up to PrEP Adherence Support Services (CoMPASS) over 24 weeks. During CM sessions, participants receive timely tangible rewards for verifiable activities demonstrating 1) PrEP initiation and adherence, and 2) engagement with medications for opioid use disorder (MOUD) and other OUD-related care. Participants who do not have high levels of biomarker-confirmed PrEP adherence at week 12 will be stepped up to receive PrEP Adherence Support Services (PASS) consisting of strengths-based case management over 12 weeks. Interventions are delivered by trained PrEP navigators, staff embedded within the respective sites. The primary outcome is sustained PrEP adherence by dried blood spot testing at 24 weeks. To inform future implementation, we are conducting implementation-focused process evaluations throughout the clinical trial.

CONCLUSIONS

Results from this protocol are anticipated to yield novel findings regarding the impact and scalability of CoMPASS to promote HIV prevention among PWID in partnership with community-based organizations. http://ClinicalTrials.gov identifier: NCT04738825.

Urine tenofovir-monitoring predicts HIV viremia in patients treated with high genetic-barrier regimens

OBJECTIVE

Access to viral load measurements is constrained in resource-limited settings. A lateral flow urine tenofovir (TFV) rapid assay (UTRA) for patients whose regimens include TFV offers an affordable approach to frequent adherence monitoring.

DESIGN

We conducted a cross-sectional study of patients to assess the utility of UTRA to predict virologic failure, defined as a viral load greater than 400 copies/ml.

METHODS

We assessed urine TFV among 113 participants at increased risk of viral failure (who had previous viral failure on this regimen or had previously been ≥30 days out of care), comparing low genetic-barrier efavirenz (EFV) regimens (n = 60) to dolutegravir (DTG)-boosted or ritonavir-boosted protease inhibitor (PI/r)-based high genetic-barrier regimens (n = 53). Dried blood spots (DBS) for TFV-diphosphate and plasma for TFV concentrations were collected, with drug resistance assessed if viral failure present.

RESULTS

Among 113 participants, 17 of 53 received DTG or PI/r had viral failure at the cross-sectional visit, with 11 (64.7%) demonstrating an undetectable urine TFV; the negative-predictive value (NPV) of undetectable UTRA for viral failure was 85% (34/40); none of the 16 sequenced had dual class drug resistance. In those treated with EFV regimens the sensitivity was lower, as only 1 (4.8%) of 21 with viral failure had an undetectable UTRA (P < 0.001).

CONCLUSIONS

Urine tenofovir-testing had a high negative-predictive value for viral failure in patients treated with DTG or ritonavir-boosted protease inhibitor regimens, where viral failure was largely explained by poor drug adherence. Frequent monitoring with inexpensive lateral flow urine TFV testing should be investigated prospectively in between viral load visits to improve viral load suppression on DTG-based first-line therapy in resource-limited settings.

A mAb for the detection of the antiretroviral drug emtricitabine

Antibody-based testing for emtricitabine (FTC), a critical component of pre-exposure prophylaxis and antiretroviral therapy, would provide low-cost detection for clinical monitoring to improve adherence. We developed a mAb (5D2) to FTC and demonstrated its high specificity and physiologically relevant linear range of detection in a competitive enzyme immunoassay. Thus, this mAb is a key reagent that will enable simple and low-cost lateral flow assays and enzyme immunoassays for adherence monitoring.

Point-of-Care Tenofovir Urine Testing for the Prediction of Treatment Failure and Drug Resistance During Initial Treatment for Human Immunodeficiency Virus Type 1 (HIV-1) Infection

BACKGROUND

Viral rebound during antiretroviral treatment (ART) is most often driven by suboptimal adherence in the absence of drug resistance. We assessed the diagnostic performance of point-of-care (POC) tenofovir (TFV) detection in urine for the prediction of viral rebound and drug resistance during ART.

METHODS

We performed a nested case-control study within the ADVANCE randomized clinical trial (NCT03122262) in Johannesburg, South Africa. Adults with human immunodeficiency virus (HIV) and newly initiating ART were randomized to receive either dolutegravir or efavirenz, tenofovir disoproxil fumarate or alafenamide, and emtricitabine. All participants with rebound ≥200 copies/mL between 24 and 96 weeks of follow-up were selected as cases and matched to controls with virological suppression <50 copies/mL. Rapid POC urine-TFV detection was performed retrospectively.

RESULTS

We included 281 samples from 198 participants. Urine-TFV was detectable in 30.7% (70/228) of cases and in 100% (53/53) of controls. Undetectable urine-TFV predicted rebound with a sensitivity of 69% [95% confidence interval {CI}: 63-75] and specificity of 100% [93-100]. In cases with virological failure and sequencing data (n = 42), NRTI drug resistance was detected in 50% (10/20) of cases with detectable urine-TFV versus in 8.3% (2/24) of cases with undetectable urine-TFV. Detectable urine-TFV predicted NRTI resistance (odds ratio [OR] 10.4 [1.8-114.4] P = .005) with a sensitivity of 83% [52-98] and specificity of 69% [50-84].

CONCLUSIONS

POC objective adherence testing using a urine-TFV test predicted viral rebound with high specificity. In participants with rebound, urine-TFV testing predicted the selection of drug resistance. Objective adherence testing may be used to rapidly provide insight into adherence, suppression, and drug resistance during ART.

Tenofovir-Diphosphate in Dried Blood Spots versus Tenofovir in Urine/Plasma for Oral Preexposure Prophylaxis Adherence Monitoring

Background

Tenofovir-diphosphate (TFV-DP) measured in dried blood spots (DBS) and tenofovir (TFV) measured in urine/plasma have been used to measure TFV-based oral pre-exposure prophylaxis (PrEP) adherence. However, there are limited data comparing these 3 metrics and their appropriate use for PrEP adherence monitoring.

Methods

We collected DBS, urine, and plasma samples from HIV-negative adults randomized to a low (2 doses/week), moderate (4 doses/week), or perfect (7 doses/week) adherence group (via directly observed therapy) of tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) for 6 weeks, followed by a 4-week washout phase. Drug concentrations were measured using liquid chromatography tandem mass spectrometry. Linear mixed-effects modeling was used to examine associations between drug concentrations and dosing time.

Results

Among 28 participants, the median age was 33 years, and 12 (43%) were female. At steady state, 25th percentile TFV-DP concentrations were 466, 779, and 1375 fmol/3 mm punch in the low, moderate, and perfect adherence group, respectively. Correlation was stronger between quantifiable TFV-DP and plasma TFV (r = 0.65; P < .01) than between TFV-DP and urine TFV (r = 0.50; P < .01). Among all participants, each additional week of cumulative dosing on average led to a mean increase of 158 fmol/3 mm punch (P < .001) in TFV-DP during the dosing phase. Each additional day after the last dose was associated with 43 fmol/3 mm punch lower TFV-DP (P = .07).

Conclusions

TFV-DP levels in DBS provide valuable insight into both dosing recency and cumulative doses from variable adherence patterns. Our observed benchmark TFV-DP concentrations were slightly higher than prior predicted estimates based on convenience samples.

Drug Resistance, Rather than Low Tenofovir Levels in Blood or Urine, Is Associated with Tenofovir, Emtricitabine, and Efavirenz Failure in Resource-Limited Settings

The high cost of viral load (VL) testing limits its use for antiretroviral therapy (ART) adherence support. A low-cost lateral flow urine tenofovir (TFV) rapid assay predicts pre-exposure prophylaxis breakthroughs, but has not yet been investigated in HIV treatment. We therefore evaluated its utility in a pilot cross-sectional study of TFV-containing ART recipients at an increased risk of virologic failure (VF). Participants who had a treatment interruption ≥30 days or had ≥1 episode of viremia (VL ≥400 copies/mL) in the previous year were recruited from a public health setting in Cape Town, South Africa. Self-reported adherence data were collected, the urine TFV assay performed, and concurrent TFV-diphosphate analyzed in dried blood spots. VL testing was done concurrently and, if viremic, genotypic HIV drug resistance testing was performed. Of 48 participants, 18 (37.5%) had VL (>400 copies/mL) at the time of the study, including 16 of 39 receiving efavirenz (EFV), 2 of 6 receiving protease inhibitors, and 0 of 3 receiving dolutegravir. Resistance testing succeeded in 17/18, of which 14 had significant mutations compromising ≥2 agents of the current EFV-based regimen. Of these 14, all had detected urine TFV. Urine TFV was undetectable in two out of three without regimen-relevant resistance; p = .02. In participants on EFV-based regimens returning to care, VF was largely due to viral resistance, where detectable urine TFV had 100% sensitivity (14/14 participants) in predicting resistance. Conversely, when undetectable, the urine-based assay could be used to preclude participants with poor adherence from undergoing costly HIV drug resistance testing.

Point-of-care semi-quantitative test for adherence to tenofovir alafenamide or tenofovir disoproxil fumarate

OBJECTIVES

Objective measurement of antiretrovirals may aid clinical interventions for improving adherence to HIV prevention or treatment regimens. A point-of-care urine test could provide real-time information about recent adherence to regimens containing tenofovir disoproxil fumarate or tenofovir alafenamide. We developed a lateral flow immunoassay (LFA) and ELISA for urinary tenofovir.

METHODS

The intensity of the LFA test line was quantified using an optical reader and visually scored 0-5 by two independent people, using a reference card. The sensitivity and specificity of both the ELISA and LFA were determined for two different tenofovir concentration cut-offs for tenofovir disoproxil fumarate and tenofovir alafenamide adherence-1500 and 150 ng/mL, respectively. To validate the assays, we measured 586 urine samples from 28 individuals collected as part of a study of tenofovir pharmacokinetics in adults, which were also measured by MS for reference.

RESULTS

Both the LFA signal and ELISA signal were each strongly correlated with drug concentrations (0.91 and 0.92, respectively). The LFA signal and ELISA were highly sensitive and specific at both thresholds (LFA sensitivity/specificity: tenofovir disoproxil fumarate, 89%/96%; and tenofovir alafenamide, 90%/96%) (ELISA sensitivity/specificity: tenofovir disoproxil fumarate, 94%/94%; and tenofovir alafenamide, 92%/84%). Visual scoring of the LFA was also highly sensitive and specific at both the tenofovir disoproxil fumarate threshold and the tenofovir alafenamide threshold (sensitivity/specificity: tenofovir disoproxil fumarate, 91%/94%; and tenofovir alafenamide, 87%/90%).

CONCLUSIONS

Our rapid semi-quantitative test can measure tenofovir concentrations relevant to both tenofovir alafenamide and tenofovir disoproxil fumarate adherence, which may support adherence-promoting interventions across a range of HIV care settings.

Antiretroviral refill histories as a predictor of future HIV viremia

Background

The use of adherence measures as markers for virologic failure (VF) has been studied. Yet, there is currently no single adherence metric recommended for VF. Antiretroviral prescription refill histories, for people living with human immunodeficiency virus (HIV), are readily accessible and can be easily quantified to an estimated adherence level.

Methods

Participants from a Midwestern US HIV clinic were retrospectively evaluated from 2018 to 2020. Refill histories (RH) and last HIV RNA for each participant were abstracted for each study year. RH were quantified as a percentage of days covered (PDC) and VF was defined as HIV RNA >200 copies/mL. PDC values were matched with subsequent year HIV RNA (matched pair). Sample t test were used to compare mean PDC level by viral suppression status and generalized estimating equations models were used to determine the predictability of PDC level for VF. An optimal PDC threshold for VF was determined using receiver operating characteristic curve analysis and Youden index.

Results

A total of 1056 participants contributed to 1923 matched pairs (PDC/HIV RNA); mean age was 48.3 years, 24% women, and 30.6% Black. PDC levels differed significantly based on dichotomized HIV RNA (2018–2019: >200: 40% [95% confidence interval {CI}, 33%–46%] vs ≤200: 85% [95% CI, 84%–87%], P < .0001; 2019–2020: >200: 45% [95% CI, 38%–51%] vs ≤200: 87% [95% CI, 86%–89%], P < .0001). Based on the Youden index value of 0.66 (sensitivity 0.77, specificity 0.89), the optimal PDC threshold predictive of VF was 52%.

Conclusions

Lower antiretroviral therapy (ART) adherence levels were predictive of future VF when PDC ≤52%.

Pre-exposure Prophylaxis Recent Adherence With Real-Time Adherence Feedback and Partner Human Immunodeficiency Virus Self-Testing: A Pilot Trial Among Postpartum Women

Background

Pre-exposure prophylaxis (PrEP) is safe and effective in postpartum women. Human immunodeficiency virus self-testing (HIVST) for male partners combined with biofeedback counseling through real-time adherence measures may improve PrEP use among postpartum women.

Methods

Between August 2020 and April 2021, we randomized postpartum women who initiated PrEP in pregnancy 1:1 to the intervention group (HIVST + biofeedback counseling after urine tenofovir test) or to standard of care ([SOC] facility-based human immunodeficiency virus [HIV] tests and routine counseling without biofeedback). The outcomes of interest were PrEP adherence in the past 48–72 hours via urine tenofovir tests and partner HIV testing, measured 1-month after randomization. Secondary outcomes included the proportion of partners who tested for HIV and the discrepancy between self-reported PrEP adherence and urine tenofovir result.

Results

We enrolled 106 women (median age = 26 years). At enrollment, 72% of women reported missing <2 doses in the past 7 days; 36% of women had tenofovir present in her urine. One month after enrollment, 62% (n = 33) of women in the intervention arm had tenofovir present in their urine compared to 34% (n = 18) in SOC (risk ratio [RR] = 1.83; 95% confidence interval [CI] = 1.19–2.82; P = .001). Two thirds of women in the intervention arm reported that her partner tested for HIV (66%; n = 35), compared to 17% (n = 9) in SOC (RR = 3.89; 95% CI = 2.08–7.27; P < .001). Self-reported PrEP adherence (took PrEP >5 of last week) with no tenofovir in urine test was lower in the intervention group (17% vs 46%; RR = 0.33; 95% CI = 0.17–0.67; P = .03). No social or clinical adverse events were reported in the intervention arm.

Conclusions

The HIVST for partners and biofeedback counseling increased levels of recent PrEP adherence, pointing to the importance of these interventions to support PrEP use in this population.

Point-of-Care Test for Assessing Tenofovir Adherence: Feasibility and Recommendations from Women in an Oral PrEP Program in Kenya and Their Healthcare Providers

Oral pre-exposure prophylaxis (PrEP) is a highly effective HIV prevention modality when taken as recommended. Women in sub-Saharan Africa may have adherence challenges that remain undisclosed to providers. Real-time measures that identify non-adherence can allow for immediate exploration of adherence challenges, counseling and interventions. We conducted a formative qualitative study in Kenya to explore oral PrEP experiences and reactions to a point-of-care urine test (UT) identifying recent (past 4 days) non-adherence to tenofovir-based PrEP among female PrEP users (25 in-depth interviews; 4 focus groups) and health care provider (10 key informant interviews). Findings indicate that use of the UT would be highly feasible in the context of regular PrEP care, largely acceptable to clients and providers, and could improve adherence. Clients emphasized the need for transparent client-centered strategies in delivering results. This formative study informs the development of tools to implement this point-of-care UT in future interventional studies and clinical settings.

Simplifying TREAtment and Monitoring for HIV (STREAM HIV): protocol for a randomised controlled trial of point-of-care urine tenofovir and viral load testing to improve HIV outcomes

INTRODUCTION

Substantial improvements in viral suppression among people living with HIV (PLHIV) are needed to end the HIV epidemic, requiring extensive scale-up of low-cost HIV monitoring services. Point-of-care (POC) tests for monitoring antiretroviral therapy (ART) adherence and viral load (VL) may be efficient and effective tools for real-time clinical decision making. We aim to evaluate the effects of a combined intervention of POC ART adherence and VL testing compared with standard-of-care on ART adherence, viral suppression and retention at 6 and 18 months post-ART initiation among PLHIV.

METHODS AND ANALYSIS

Simplifying TREAtment and Monitoring for HIV (STREAM HIV) is a two-arm, open-label, randomised controlled superiority trial of POC urine tenofovir (POC TFV) and VL monitoring in PLHIV. We aim to enrol 540 PLHIV initiating a first-line ART regimen at a public HIV clinic in South Africa. Participants will be randomised 1:1 to the intervention or control arm. Intervention arm participants will receive monthly POC TFV testing for the first 5 months and POC VL testing at months 6 and 12. Intervention arm participants will also receive reflex POC TFV testing if viraemic and reflex HIV drug resistance testing for those with viraemia and detectable TFV. Control arm participants will receive standard-of-care, including laboratory-based VL testing at months 6 and 12. Primary outcomes include ART adherence (TFV-diphosphate concentration) at 6 months and viral suppression and retention at 18 months. Secondary outcomes include viral suppression and retention at 6 months, TFV-diphosphate concentration at 18 months, cost and cost-effectiveness of the intervention and acceptability of the intervention among PLHIV and healthcare workers.

ETHICS AND DISSEMINATION

STREAM HIV has received ethical approval from the University of Washington Institutional Review Board (STUDY00007544), University of KwaZulu-Natal Biomedical Research Ethics Committee (BREC/00000833/2019) and Division of AIDS Regulatory Support Center (38509). Findings will be disseminated at international conferences and in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04341779.

Brief Report: No Difference in Urine Tenofovir Levels in Patients Living With HIV on Unboosted Versus Dose-Adjusted Boosted Tenofovir Alafenamide

BACKGROUND

Tenofovir alafenamide (TAF) is increasingly used in HIV treatment, with or without agents that require pharmacologic boosters such as ritonavir/cobicistat. Boosters increase TAF levels, so the TAF dose is lowered in single-pill combinations. We hypothesized that individuals on dose-adjusted boosted TAF would have similar urine tenofovir (TFV) concentrations to those on unboosted TAF.

SETTING/METHODS

We collected urine samples from patients with HIV on TAF, with evidence of virologic suppression and high self-reported adherence at 2 San Francisco clinics from June 2019 to January 2020. We measured urine TFV levels by liquid chromatography/tandem mass spectrometry and used linear regression to compare natural log-transformed urine TFV levels for patients on boosted versus unboosted TAF.

RESULTS

Our analysis included 30 patients on unboosted TAF (25 mg daily TAF) and 15 on boosted TAF (12 on 10 mg daily TAF and 3 on 25 mg daily TAF). Patients on unboosted vs. boosted TAF had similar baseline age, weight, sex, and creatinine. In unadjusted univariate linear regression, there were no significant differences in urine TFV levels based on presence/absence of boosting after TAF dose reduction to 10 mg (geometric mean ratio 1.07; 95% confidence interval: 0.53 to 2.16). This finding was unchanged in adjusted analysis.

CONCLUSIONS

No significant differences in urine TFV levels were seen for patients on unboosted vs. boosted dose-reduced TAF. These results have important implications for our forthcoming point-of-care urine immunoassay for TAF, implying that separate adherence cutoffs will not be necessary for patients on boosters and dose-reduced TAF. A single POC TAF immunoassay will, thus, support monitoring on most TAF-based antiretroviral therapy.

Ten Years of Lateral Flow Immunoassay Technique Applications: Trends, Challenges and Future Perspectives

The Lateral Flow Immunoassay (LFIA) is by far one of the most successful analytical platforms to perform the on-site detection of target substances. LFIA can be considered as a sort of lab-in-a-hand and, together with other point-of-need tests, has represented a paradigm shift from sample-to-lab to lab-to-sample aiming to improve decision making and turnaround time. The features of LFIAs made them a very attractive tool in clinical diagnostic where they can improve patient care by enabling more prompt diagnosis and treatment decisions. The rapidity, simplicity, relative cost-effectiveness, and the possibility to be used by nonskilled personnel contributed to the wide acceptance of LFIAs. As a consequence, from the detection of molecules, organisms, and (bio)markers for clinical purposes, the LFIA application has been rapidly extended to other fields, including food and feed safety, veterinary medicine, environmental control, and many others. This review aims to provide readers with a 10-years overview of applications, outlining the trends for the main application fields and the relative compounded annual growth rates. Moreover, future perspectives and challenges are discussed.

Lower Urine Tenofovir Concentrations Among Individuals Taking Tenofovir Alafenamide Versus Tenofovir Disoproxil Fumarate: Implications for Point-of-Care Testing

From directly observed therapy studies, urine tenofovir (TFV) levels were 74% lower when taking tenofovir alafenamide (TAF) vs tenofovir disoproxil fumarate. Urine TFV remains quantifiable across a range of TAF adherence patterns, but a separate point-of-care lateral flow immunoassay with a lower TFV threshold will be needed to support TAF adherence monitoring.

Conference proceedings from the 23rd Bangkok International Symposium on HIV Medicine

The Bangkok International Symposium on HIV Medicine is the longest running HIV conference in the Asia-Pacific, that provides professional healthcare workers with the latest information on HIV and related fields. For the first time, this event was held as a virtual symposium due to the COVID-19 pandemic and registration was free to everyone. More than 1800 people viewed the symposium from 41 countries. The first sessions reviewed COVID-19 and had a panel representing physicians from Australia, Myanmar, Indonesia and Thailand, who shared experiences in managing HIV care during the pandemic. For the first time, we had sessions on the WHO’s vision for integrating HIV care delivery models, and a number of physicians shared the innovative models that have been developed in their clinics.

Point-of-care and Near Real-time Testing for Antiretroviral Adherence Monitoring to HIV Treatment and Prevention

PURPOSE OF REVIEW

In this report, we review the need for point-of-care (POC) or near real-time testing for antiretrovirals, progress in the field, evidence for guiding implementation of these tests globally, and future directions in objective antiretroviral therapy (ART) or pre-exposure prophylaxis (PrEP) adherence monitoring.

RECENT FINDINGS

Two cornerstones to end the HIV/AIDS pandemic are ART, which provides individual clinical benefits and eliminates forward transmission, and PrEP, which prevents HIV acquisition with high effectiveness. Maximizing the individual and public health benefits of these powerful biomedical tools requires high and sustained antiretroviral adherence. Routine monitoring of medication adherence in individuals receiving ART and PrEP may be an important component in interpreting outcomes and supporting optimal adherence. Existing practices and subjective metrics for adherence monitoring are often inaccurate or unreliable and, therefore, are generally ineffective for improving adherence. Laboratory measures of antiretroviral concentrations using liquid chromatography tandem mass spectrometry have been utilized in research settings to assess medication adherence, although these are too costly and resource-intensive for routine use. Newer, less costly technologies such as antibody-based methods can provide objective drug-level measurement and may allow for POC or near-patient adherence monitoring in clinical settings. When coupled with timely and targeted counseling, POC drug-level measures can support adherence clinic-based interventions to ART or PrEP in near real time.

Real-Time Monitoring and Point-of-Care Testing: A Review of the Current Landscape of PrEP Adherence Monitoring

BACKGROUND

Despite pre-exposure prophylaxis (PrEP) being highly effective at preventing HIV, HIV infections among individuals prescribed PrEP continue to occur. The vast majority of these new infections occur among individuals with sub-optimal adherence. One factor that is likely to decrease HIV incidence among PrEP users is a real-time, objective measurement of adherence. Monitoring adherence to PrEP can identify those at risk of becoming lost to follow-up and therefore at greater risk of HIV infection, those in need of additional layers of support to overcome barriers to PrEP, and individuals who need enhanced adherence support.

OBJECTIVE

This paper reviews subjective and objective methods for monitoring PrEP including self-report, drug level monitoring (including serum, plasma, peripheral blood mononuclear cells [PBMC], red blood cell dried blood spots [DBS], hair, and urine) and by measuring participant interaction with the study drug (pill counts, medication event monitoring systems [MEMS] caps).

CLINICAL USE

A multitude of methods exist for monitoring and supporting adherence. Objective monitoring using DBS and urine will provide a more accurate picture of adherence compared to subjective and non-biomarker objective methods. Preliminary data show that detection of non-adherence using biomarkers, followed by augmented adherence support and counseling, is associated with improved adherence, although more research is needed. PrEP providers will need knowledge of and access to these various strategies, which will require investment and resource allocation from clinics and other PrEP care sites to provide these tools.

Detectable HIV RNA in late pregnancy associated with low tenofovir hair levels at time of delivery among women living with HIV in the United States

OBJECTIVE

We evaluated peripartum tenofovir (TFV) exposure via hair measures among women living with HIV in the United States.

DESIGN

Observational cohort study.

METHODS

Hair samples were collected at or shortly after childbirth among mothers enrolled in the Surveillance Monitoring for Antiretroviral Therapy Toxicities Study of the Pediatric HIV/AIDS Cohort Study between 6/2014 and 7/2016. Among mothers receiving TFV disoproxil fumarate (TDF)-based regimens during pregnancy, TFV hair concentrations were analyzed using liquid chromatography/tandem mass spectrometry. Weight-normalized TFV concentrations were log10 transformed. Multivariable linear regression assessed correlates of TFV concentrations.

RESULTS

Overall, 121 mothers on TDF-based antiretroviral therapy during pregnancy had hair specimens tested for TFV concentrations and were included in the analysis. Median age at delivery was 31 years [interquartile range (IQR) 26-36]; 71% self-identified as non-Hispanic black, and 10% had unsuppressed viral loads in late pregnancy (HIV RNA ≥ 400 copies/ml). Median time from birth to hair collection was 3 days (IQR 1-14) and median TFV hair concentration was 0.02 ng/mg (IQR 0.01-0.04). In multivariable models, an unsuppressed viral load in late pregnancy was associated with 80% lower adjusted mean peripartum TFV concentrations than pregnancies with viral suppression (95% confidence interval: -90% to -59%, P < 0.001). Use of TDF only in the first trimester and attaining high school graduation were also associated with lower TFV hair concentrations.

CONCLUSION

Unsuppressed viral load during late pregnancy was strongly associated with lower maternal TFV hair concentrations at birth, though viremia was rare. Efforts to improve maternal virological outcomes and eliminate vertical HIV transmission could incorporate drug exposure monitoring using hair or other metrics.

Urine Tenofovir Levels Measured Using a Novel Immunoassay Predict Human Immunodeficiency Virus Protection

New tools are needed to support pre-exposure prophylaxis (PrEP) adherence for human immunodeficiency virus (HIV) prevention, including those that enable real-time feedback. In a large, completed PrEP trial, adequate urine tenofovir levels measured using a novel immunoassay predicted HIV protection and showed good sensitivity and specificity for detectable plasma tenofovir.

Brief Report: High Accuracy of a Real-Time Urine Antibody-Based Tenofovir Point-of-Care Test Compared With Laboratory-Based ELISA in Diverse Populations

BACKGROUND

Therapeutic drug monitoring measures antiretroviral adherence more accurately than self-report but has not been available at the point-of-care (POC) until now. We compare a novel POC test for urine tenofovir to laboratory-based enzyme-linked immunosorbent assay (ELISA) testing in diverse patient populations urine pre-exposure prophylaxis (PrEP).

SETTING

Urine samples were analyzed using ELISA and the POC lateral flow immunoassay (LFA) test from 2 cohorts of PrEP users taking tenofovir disoproxil fumarate/emtricitabine: the Partners PrEP Study, which recruited Kenyan and Ugandan heterosexual men and women, and the IBrEATHe Study, which recruited US transgender women and men using gender-affirming hormone therapy.

METHODS

We calculated the sensitivity, specificity, and accuracy of the POC test compared with ELISA at a cutoff of 1500 ng/mL.

RESULTS

Overall, 684 urine samples were tested from 324 participants in the 2 cohorts. In Partners PrEP, 454 samples from 278 participants (41% women) were tested with a median age of 33 years. In IBrEATHe, 231 samples from 46 individuals (50% transwomen) were tested with a median age of 31 years. Comparison of the LFA read-out to ELISA yielded 100% sensitivity [97.5% one-sided confidence interval (CI) = 99.3%], 98.3% specificity (95% CI = 95.2% to 99.7%), and 99.6% accuracy (95% CI = 98.7% to 99.9%).

CONCLUSION

The sensitivity, specificity, and accuracy of a novel POC test for urine tenofovir all exceeded 98% when compared with a laboratory-based ELISA method when tested in diverse patient populations. Given the LFA's high accuracy and expected low cost, this POC test is a promising tool to support antiretroviral adherence that could be widely scalable to real-world clinical settings.

Approaches to Objectively Measure Antiretroviral Medication Adherence and Drive Adherence Interventions

PURPOSE OF REVIEW

Traditional methods to assess antiretroviral adherence, such as self-report, pill counts, and pharmacy refill data, may be inaccurate in determining actual pill-taking to both antiretroviral therapy (ART) or pre-exposure prophylaxis (PrEP). HIV viral loads serve as surrogates of adherence on ART, but loss of virologic control may occur well after decreases in adherence and viral loads are not relevant to PrEP.

RECENT FINDINGS

Pharmacologic measures of adherence, electronic adherence monitors, and ingestible electronic pills all serve as more objective metrics of adherence, surpassing self-report in predicting outcomes. Pharmacologic metrics can identify either recent adherence or cumulative adherence. Recent dosing measures include antiretroviral levels in plasma or urine, as well as emtricitabine-triphosphate in dried blood spots (DBS) for those on tenofovir-emtricitabine-based therapy. A urine tenofovir test has recently been developed into a point-of-care test for bedside adherence monitoring. Cumulative adherence metrics assess adherence over weeks to months and include measurement of tenofovir-diphosphate in peripheral blood mononuclear cells or DBS, as well as ART levels in hair. Electronic adherence monitors and ingestible electronic pills can track pill bottle openings or medication ingestion, respectively. New and objective approaches in adherence monitoring can be used to detect nonadherence prior to loss of prevention efficacy or virologic control with PrEP or ART, respectively.

Monoclonal antibodies with subnanomolar affinity to tenofovir for monitoring adherence to antiretroviral therapies: from hapten synthesis to prototype development

Approximately 32 million people have died of HIV infection since the beginning of the outbreak, and 38 million are currently infected. Among strategies adopted by the Joint United Nations Programme on HIV/AIDS to end the AIDS global epidemic, the treatment, diagnosis, and viral suppression of the infected subjects are considered crucial for HIV prevention and transmission. Although several antiretroviral (ARV) drugs are successfully used to manage HIV infection, their efficacy strictly relies on perfect adherence to the therapy, which is seldom achieved. Patient supervision, especially in HIV-endemic, low-resource settings, requires rapid, easy-to-use, and affordable analytical tools, such as the enzyme-linked immunosorbent assay (ELISA) and especially the lateral flow immunoassay (LFIA). In this work, high-affinity monoclonal antibodies were generated to develop ELISA and LFIA prototypes for monitoring tenofovir (TFV), an ARV drug present in several HIV treatments. TFV was functionalized by inserting a carboxylated C5-linker at the phosphonic group of the molecule, and the synthetic derivative was conjugated to proteins for mice immunization. Through a rigorous screening strategy of hybridoma supernatants, a panel of monoclonal antibodies strongly binding to TFV was obtained. Following antibody characterization for affinity and selectivity by competitive ELISA, a LFIA prototype was developed and tentatively applied to determine TFV in simulated urine. The point-of-care test showed ultra-high detectability (the visual limit of detection was 2.5 nM, 1.4 ng mL^-1), excellent selectivity, and limited proneness to matrix interference, thus potentially making this rapid method a valuable tool for the on-site assessment of patient adherence to ARV therapy.

Plasma pharmacokinetics and urinary excretion of tenofovir following cessation in adults with controlled levels of adherence to tenofovir disoproxil fumarate

OBJECTIVES

The aim was to fully characterize the plasma and urine washout pharmacokinetics of tenofovir (TFV) in adults following 6 weeks of controlled levels of tenofovir disoproxil fumarate (TDF) adherence, in order to inform the utility of clinic-based adherence testing.

DESIGN

This was a three-arm, randomized, open-label study in adult volunteers. Participants were randomized to receive TDF 300 mg/emtricitabine (FTC) 200 mg as (1) 7 doses/week (perfect adherence), (2) 4 doses/week (moderate adherence), or (3) 2 doses/week (low adherence). Plasma and urine samples were collected regularly during the 6-week dosing phase and for 4 weeks following drug cessation.

RESULTS

Twenty-eight adults were included in this analysis. Median (range) age was 33 (20-49) years. No differences in TFV pharmacokinetic parameters during the washout were observed across the study arms. Small differences in TFV plasma concentrations occurred across arms between 4 and 10 h post-dose. The cumulative amount of TFV excreted in urine was not different at 24 h post-dose, but at 148 h it was 24.8 mg, 21.0 mg, and 17.2 mg for the perfect, moderate, and low adherence arms, respectively (p = 0.043).

CONCLUSIONS

Among adults with different TDF adherence patterns, relative differences in plasma concentrations and cumulative urine extraction of TFV were minor following cessation. TFV measurement in plasma or urine is more indicative of last drug ingestion, rather than prior dose patterns.

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.

The crosstalk between antiretrovirals pharmacology and HIV drug resistance

INTRODUCTION

The clinical development of antiretroviral drugs has been followed by a rapid and concomitant development of HIV drug resistance. The development and spread of HIV drug resistance is due on the one hand to the within-host intrinsic HIV evolutionary rate and on the other to the wide use of low genetic barrier antiretrovirals.

AREAS COVERED

We searched PubMed and Embase on 31 January 2020, for studies reporting antiretroviral resistance and pharmacology. In this review, we assessed the molecular target and mechanism of drug resistance development of the different antiretroviral classes focusing on the currently approved antiretroviral drugs. Then, we assessed the main pharmacokinetic/pharmacodynamic of the antiretrovirals. Finally, we retraced the history of antiretroviral treatment and its interconnection with antiretroviral worldwide resistance development both in , and middle-income countries in the perspective of 90-90-90 World Health Organization target.

EXPERT OPINION

Drug resistance development is an invariably evolutionary driven phenomenon, which challenge the 90-90-90 target. In high-income countries, the antiretroviral drug resistance seems to be stable since the last decade. On the contrary, multi-intervention strategies comprehensive of broad availability of high genetic barrier regimens should be implemented in resource-limited setting to curb the rise of drug resistance.