Project ADHERE: Clinical Proof-of-Concept of a Tenofovir (TFV) Aptamer-Based Biosensor

Truvada®, an oral pill comprised of two anti-retroviral compounds, emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF), is currently the only drug combination approved for pre-exposure prophylaxis (PrEP) in women exposed to high HIV risk through vaginal acquisition. Adherence to the one pill per day regimen is crucial for its effectiveness in reducing the risk of acquiring HIV. Currently, there is no available point of care diagnostic test to quickly measure blood levels of tenofovir in the clinic. This study will determine whether a tenofovir (TFV) aptamer-based biosensor (aptasensor) can detect TFV in biological fluids from women randomized to different dosing regimens representing high and low adherence.

Project ADHERE is a pilot, prospective, randomized study which will screen approximately 20 healthy, non-pregnant, HIV negative, premenopausal women (aged 18-50) at Eastern Virginia Medical School (EVMS) who are not at risk of pregnancy and are at low risk for sexually transmitted infections (STIs) in order to have approximately 14 women complete all study visits. The women will be randomized to one of two different dosing regimens of Truvada for up to 14 days. The low adherence cohort will take a total of 3 Truvada pills per week while the high adherence cohort will be assigned to take daily dosing, 7 pills per week. At screening (visit 1), we will screen women for HIV-1 and perform STI tests and serum screening for Hepatitis B and creatinine clearance prior to commencing oral PrEP, consistent with oral PrEP initiation guidelines. After screening labs return, they will come to the clinic for visit 2 when baseline blood, urine, and vaginal fluid will be collected, randomize participants to the dosing regimen, watch the participants ingest the first dose, and then direct to them to take subsequent doses in their homes. Reminder text messages will be sent to the participants to facilitate doses being taken at the same time of day upon which they will text message the coordinator after ingesting the pill. Participants will return 24 hours, 7 days, and 14 days after visit 2 for pre-dose collection of blood, urine, and vaginal fluid samples (visits 3, 4, and 5, respectively). For all visits, participants will not to take the next prescribed dose before coming to the clinic. Once samples are collected, participants will ingest the next scheduled pill. However, for the high adherence regimen, the women will take their last dose on day 14 and then come to the clinic 24 hours later on day 15 for collection of samples. Regardless of regimen, sample collection will take place no earlier than 24 hours after last dosing to prevent white coat effects. Samples will be brought to the laboratory for processing and eventual measurement of TFV levels by the TFV aptasensor. Aliquots of plasma and urine will also be analyzed by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) so sensitivity and specificity of the aptasensor can be determined. The ability of the TFV aptasensor to distinguish levels associated with high and low adherence will also be assessed.