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.

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.

OBJECTIVE: HIV prevention and treatment studies demonstrate that pharmacologic adherence metrics are more accurate than self-report. Currently available metrics use liquid-chromatography/tandem-mass-spectrometry (LC-MS/MS), which is expensive and laboratory-based. We developed a specific and sensitive antibody against tenofovir, the backbone of treatment and prevention, but conversion to a lateral flow assay (LFA) - analogous to a urine pregnancy test - is required for point-of-care testing. We describe the development of the first LFA to measure antiretroviral adherence in real-time. METHODS: Previous work in a directly observed therapy study of providing tenofovir disoproxil fumarate (TDF) to HIV-noninfected volunteers at various simulated adherence patterns defined the appropriate cut-off for the LFA (1500 ng tenofovir/ml urine). We developed the LFA using a sample pad for urine; a conjugate pad coated with TFV-specific antibodies conjugated to colloidal gold nanoparticles; a nitrocellulose membrane striped with tenofovir-antigen (test line) and a control line; with an absorbent pad to draw urine across the reaction membrane. RESULTS: We tested 300 urine samples collected from the directly observed therapy study by this LFA and the gold-standard method of LC-MS/MS. The LFA demonstrated 97% specificity (95% CI 93-99%) and 99% sensitivity (94-100%) compared with LC-MS/MS. The LFA accurately classified 98% of patients who took a dose within 24 h as adherent. CONCLUSION: We describe the development and validation of the first point-of-care assay to measure short-term adherence to HIV prevention and treatment in routine settings. The assay is low-cost, easy-to-perform and measures the breakdown product (tenofovir) of both TDF and tenofovir alafenamide (TAF). This assay has the potential to improve HIV and PrEP outcomes worldwide by triggering differentiated service delivery with further study merited.

Low tenofovir level in urine by a novel immunoassay is associated with seroconversion in a preexposure prophylaxis demonstration project.

OBJECTIVE: We examined the relationship between urine tenofovir (TFV) levels measured with a novel immunoassay, which permits point-of-care testing, with HIV seroconversion and objective adherence metrics in a large preexposure prophylaxis (PrEP) demonstration project. DESIGN: Secondary analysis of stored specimens from an open-label PrEP cohort study. METHODS: We examined the association between undetectable urine TFV levels and HIV seroconversion in iPrEx open-label extension using generalized estimating equations. We examined rank correlations between levels of TFV and emtricitabine in urine, dried blood spots (DBS), and hair and determined the sensitivity and specificity of undetectable urine TFV for predicting dosing cut-offs in DBS. RESULTS: The median urinary TFV level was 15 000 ng/ml in those who remained HIV-negative (n = 105; interquartile range: 1000-45 000); 5500 in those who eventually seroconverted (n = 11; interquartile range: 1000-12 500); and all were undetectable at seroconversion (n = 9; P < 0.001). Decreasing strata of urine TFV levels were associated with future HIV seroconversion (P = 0.03). An undetectable urine TFV was 100% sensitive and 81% specific when compared with an undetectable DBS TFV-diphosphate level and 69% sensitive, but 94% specific when compared with low adherence by DBS (<2 doses/week). CONCLUSION: Urine TFV detection by a novel antibody-based assay was associated with protection from HIV acquisition among individuals on PrEP. Urine TFV levels were correlated with hair and DBS levels and undetectable urine TFV was 100% sensitive in detecting nonadherence. By implementing the immunoassay into a point-of-care strip test, PrEP nonadherence could be detected in real-time, allowing rapid intervention.

Brief Report: Validation of a Urine Tenofovir Immunoassay for Adherence Monitoring to PrEP and ART and Establishing the Cutoff for a Point-of-Care Test.

BACKGROUND: Current pharmacologic adherence monitoring for antiretrovirals involves expensive, labor-intensive liquid chromatography/tandem mass spectrometry (LC-MS/MS)-based methods. Antibody-based assays can monitor and support adherence in real time. We developed a tenofovir (TFV)-based immunoassay and further validated it in a directly observed therapy (DOT) study. DESIGN: Pharmacologic DOT study of TFV disoproxil fumarate (TDF)/emtricitabine (FTC) administered to HIV-noninfected volunteers. METHODS: The TARGET study provided directly observed TDF 300 mg/FTC 200 mg 7 (high adherence), 4 (moderate), and 2 doses/week (low) to 30 volunteers (10/group) in Thailand, collecting a total of 637 urine samples over 6 weeks of administration and during washout. ELISA measured urine TFV levels by the immunoassay and LC-MS/MS-based concentrations served as the gold standard. A mixed-effects regression model evaluated cutoffs for a point-of-care assay. Performance characteristics of the immunoassay were compared with LC-MS/MS at a chosen cutoff. RESULTS: Median TFV levels were 12,000 ng/mL by the immunoassay 1 day after dosing; 5000 ng/mL 2 days after dosing; 1500 ng/mL 3 days after dosing; and below the lower limit of quantification thereafter (≥4 days). An immunoassay cutoff of 1500 ng/mL accurately classified 98% of patients who took a dose 24 hours ago as adherent. The specificity and sensitivity of the immunoassay compared with LC-MS/MS at the 1500 ng/mL cutoff were 99% and 94%; the correlation between TFV levels by the 2 assays was high (0.92, P < 0.00001). CONCLUSIONS: We have developed a novel TFV immunoassay that is highly specific, sensitive, and correlates strongly with LC-MS/MS measurements in a large DOT study. Adherence benchmarks from this DOT study will guide the development of a low-cost rapid point-of-care test for pre-exposure prophylaxis and antiretroviral treatment adherence monitoring and interventions.

Development and Validation of an Immunoassay for Tenofovir in Urine as a Real-Time Metric of Antiretroviral Adherence.

BACKGROUND: Pharmacologic adherence measures were critical to the interpretation of the tenofovir (TFV)-disoproxil-fumarate/emtricitabine (TDF/FTC) PrEP trials. These measures are being incorporated into PrEP demonstration projects, but currently-available metrics in plasma, cells, hair or urine involve expensive and time-intensive mass-spectrometry (MS)-based methods. No point-of-care method to assess PrEP adherence in real-time has yet been implemented. Antibody-based tests allow for low-cost, easy-to-perform, point-of-care drug detection. In this study, we developed an antibody-based TFV immunoassay and evaluated its test characteristics among individuals taking TDF/FTC. METHODS: We synthesized possible immunogens based on TFV's molecular structure, injected rabbits with the conjugated derivatives, and bled them monthly for subsequent ELISA-testing for TFV-specific antibodies. We purified an antibody with specific TFV binding and created dose-response curves for ELISA-quantification. We then quantified TFV in urine from human participants not taking TDF/FTC and from individuals taking daily TDF/FTC 300 mg/200 mg for 7 days with a 7-day washout period using ELISA with this TFV-specific antibody. ELISA results were compared with the gold-standard test for TFV detection/quantification using liquid-chromatography-tandem-MS (LC-MS/MS). FINDINGS: None of the urine samples from 115 participants not taking TDF/FTC showed ELISA- reactivity, indicating 100% specificity (95% CI 97-100%) of the immunoassay. Among participants taking TDF/FTC, 67 of 70 samples positive by LC-MS/MS were positive by the ELISA-immunoassay for an estimated diagnostic sensitivity of 96% (95% CI 88-99%). The precision of the assay was high (coefficient of variationb15%). The rank correlation between ELISA and LC-MS/MS values in the 70 quantitative urine TFV levels positive by LC-MS/MS across a wide range of concentrations among participants on TDF/FTC was high (r = 0.96). INTERPRETATION: Our antibody-based immunoassay for measuring TFV in urine performed well compared to the gold-standard of LC-MS/MS among individuals taking TDF/FTC. A sensitive and specific immunoassay paves the way for real-time monitoring/feedback on recent adherence to TFV-based regimens, which should optimize interpretation and outcomes during PrEP and ART roll-out.

Detection of synthetic cannabinoids in oral fluid using ELISA and LC-MS-MS.

Synthetic cannabinoids are often referred to as 'Spice' or K2 compounds. Detection of these compounds in oral fluid has, to date, been limited to chromatographic procedures such as liquid chromatography with tandem mass spectrometry detection. We report the first analytical immunoassay for the screening of some synthetic cannabinoids in oral fluid specimens collected with the Quantisal™ device. JWH-200 was chosen as the calibration standard, because parent compounds, not metabolites, are predominantly detected in oral fluid. The immunoassay is capable of detecting JWH-200, JWH-018, JWH-073, JWH-022, AM-2201, AM-2232 and AM-1220. The assay was validated according to accepted laboratory protocols and applied to 32 authentic oral fluid specimens previously analyzed using LC-MS-MS at an accredited laboratory. The assay is sensitive, with a cutoff concentration of 0.25 ng/mL, and has a wide working range from 0.1 to 5 ng/mL. Intra- and interday precision were determined to be <10%. The screening method was completely validated and characterized; critical aspects of the screening included the incorporation of a preincubation step that improves the sensitivity of the assay to allow relevant concentrations of synthetic compounds in oral fluid to be detected.

Immunoassay screening of diphenhydramine (Benadryl®) in urine and blood using a newly developed assay.

Diphenhydramine (DPH) is a common over the counter antihistamine that produces drowsiness and has the potential to cause driving under the influence of drugs-related accidents. To date there are no commercially available immunoassay screening kits for its detection in biological fluids such as urine and/or blood. We describe a newly developed enzyme-linked immunosorbent assay (ELISA) screen and report on its utility in the analysis of authentic specimens taken from volunteers. The assay is specific for detection of DPH and does not detect closely related antihistamines like brompheniramine, chlorpheniramine, and doxylamine. There is a varying amount of cross-reactivity seen with certain tricyclic compounds, due to similarities in side chain structure with DPH. Intra- and interday precision of the assay were determined to be less than 10%. The assay is highly sensitive and has a working range from 1 to 500 ng/mL for urine and 1 to 250 ng/mL for blood. The assay was further validated with authentic urine and blood specimens obtained from volunteers and coroner's laboratories.

Development and validation of ELISA and GC-MS procedures for the quantification of dextromethorphan and its main metabolite dextrorphan in urine and oral fluid.

The development of a highly sensitive enzyme-linked immunosorbent assay and gas chromatography-mass spectrometry confirmation method for the detection of dextromethorphan and its major metabolite dextrorphan in urine and oral fluid is described. For the screening assay, the intraday precision was less than 8% for urine and less than 5% for oral fluid. The interday precision was less than 10% for both drugs in urine and oral fluid. For the confirmatory procedure, both inter- and intraday precision was less than 5% for both matrices. The detection limit for both methods was 1 ng/mL. The quantifying ions chosen from the full scan mass spectra were m/z 271 for dextromethorphan, m/z 329 for dextrorphan, and m/z 332 for tri-deuterated dextrorphan-d(3). A high recovery yield (> 93%) from the Quantisal oral fluid collection device was achieved, and the drugs were stable in the collection device for at least 10 days at room temperature. The extracted drugs from both matrices were stable for at least 48 h while kept at room temperature. Both screening and confirmatory procedures were applied to authentic urine and oral fluid specimens obtained from volunteers following therapeutic ingestion of dextromethorphan.