Urine as a Biomarker for Adherence

The current techniques to measure antiretrovirals (ARVs) in hair and other biomatrices, such as plasma and dried blood spots, require spectrometry machines and specialized personnel. Antibody-based tests (lateral flow immunoassays)(1, 2) are low-cost, enable drug detection to occur within minutes, and can be performed by non-trained personnel, research participants or patients after self-collection.(3) The most well-known lateral flow immunoassay is the urine-based pregnancy test.

The UCSF HALhas now developed a collaboration with Alere™ Rapid Diagnostics, a company with vast expertise in point of care (POC) assays, to develop an immunoassay that quantitates TFV levels in urine.(4-6) The test is sensitive (96%), specific (100%), precise (coefficient of variation <15%), and quantitates TFV levels in urine as accurately as LC-MS/MS (correlation between TFV levels by both assays 0.96) in a study of HIV-negative patients taking PrEP with TDF/FTC.(5), Figure 1. We have also demonstrated that low levels of TFV by this urine assay predict future PrEP seroconversion in a large demonstration project.(4) Moreover, we have determined the appropriate adherence cut-off for the POC urine assay using samples from a directly-observed therapy study where TDF/FTC was administered to HIV-noninfected volunteers.(6) The immunoassay has now being translated to a corresponding lateral flow assay (7) for POC adherence testing (Figure 2).

Advantages of urine for point-of-care adherence testing

Compared to other biomatrices, urine collection is non-invasive and can be readily self-collected. Studies have shown that TFV in urine is stable at room temperature for up to seven days (8) and also in cryopreserved specimens (5). As TFV is used in the backbone of most HIV treatment regimens worldwide, either in the form of TDF (9) or tenofovir alafenamide (TAF), urine monitoring of TFV would assess adherence on most HIV treatment regimens and on TDF/FTC-based PrEP. Moreover, POC urine testing strips can be mailed to participants with instructions for collecting the urine and conducting the assay (similar to a home pregnancy test). in order to help motivate adherence or record adherence for research studies. The test is low cost (<$2/test), easy to perform and assesses short-term adherence (over 4 days) within 5 minutes.  The assay is now ready for research studies to further evaluate its use so contact the HAL for collaborations.

Fig. 2. Prototype of urine-based point of care rapid testing strip

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  2. Pecoraro V, Banfi G, Germagnoli L, Trenti T. A systematic evaluation of immunoassay point-of-care testing to define impact on patients' outcomes. Ann Clin Biochem 2017;54(4):420-431.
  3. Bang HI, Jang MA, Lee YW. Evaluation of the Triage TOX Drug Screen Assay for Detection of 11 Drugs of Abuse and Therapeutic Drugs. Ann Lab Med 2017;37(6):522-525.
  4. Spinelli MA, Glidden DV, Rodrigues W, Wang G, Vincent M, Okochi H, Kuncze K, Mehrotra M, Defechereux P, Buchbinder SP, Grant RM, Gandhi M. Low tenofovir level in urine by a novel immunoassay is associated with seroconversion in a PrEP demonstration project. AIDS 2019
  5. Gandhi M, Bacchetti P, Rodriguez W, Spinelli M, Koss CA, Drain PK, Baeten JM, Mugo NR, Ngure K, Benet LZ, Okochi H, Wang G, Vincent M. Development and Validation of an Immunoassay for Tenofovir in Urine as a Real-Time Metric of Antiretroviral Adherence. EClinical Medicine (Published by The Lancet) 2018; https://doi.org/10.1016/j.eclinm.2018.08.004.
  6. Gandhi M, Bacchetti P, Spinelli MA, Okochi H, Baeten JM, Siriprakaisil O, Klinbuayaem V, Rodrigues WC, Wang W, Vincent M, Cressey TR, Drain PK.  Validation of a Urine Tenofovir Immunoassay for Adherence Monitoring to PrEP and ART and Establishing the Cut-Off for a Point-of-Care Test. JAIDS 2019 (in press).
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  8. Koenig HC, Mounzer K, Daughtridge GW, Sloan CE, Lalley-Chareczko L, Moorthy GS, et al. Urine assay for tenofovir to monitor adherence in real time to tenofovir disoproxil fumarate/emtricitabine as pre‐exposure prophylaxis. HIV Med 2017;18(6):412-41
  9. Updated Recommendations on First-Line and Second-Line Antiretroviral Regimens and Post-Exposure Prophylaxis and Recommendations on Early Infant Diagnosis of HIV. Geneva: World Health Organization; 2018 July 2018.