Biomarkers for Event-driven PrEP Adherence

Men who have sex with men (MSM) continue to be disproportionately affected by HIV. In 2014, MSM made up approximately 2% of the U.S. population but accounted for 70% of the new HIV infections. The majority of MSM acquire HIV after exposure to the rectal mucosa through receptive anal intercourse without condoms. Pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP) are recommended for MSM who may be exposed to HIV to prevent infection. Current recommendations for PrEP are to take the combination anti-HIV drug, tenofovir+emtricitabine (TDF/FTC), on a daily basis for the duration of someone's HIV risk exposure period, which could be months or years. For PEP, a three-drug anti-HIV medication is recommended within 72 hours of a possible exposure for a 28-day course. While PrEP and PEP are effective, some people find it difficult to follow the recommended regimen. Therefore, additional short-course dosing regimens for PrEP and PEP are being implemented, such as on-demand or event-driven PrEP (ED-PrEP). This dosing regimen has patients take two doses of PrEP 2 to 24 hours before sex, one dose 24 hours after sex, and another dose 48 hours after sex. This study seeks to evaluate the usefulness of biomarkers to confirm self-reported adherence to ED-PrEP in MSM. The study drug provided in this study will not protect participants from HIV or treat any active infection. This study will recruit 40 HIV-negative MSM aged 18-59 in good general health. Participants will be sequentially assigned to one of four study arms which will determine when they will take doses of the study drug and give specimen samples. All participants will provide written informed consent at the first study visit and undergo a screening medical history, physical exam, and safety laboratory tests. All participants will take at least 4 doses (pills) of the study drug. At study visits, participants will return to donate blood, hair, and urine samples, and a finger stick. All biologic specimens collected will be transferred to the Centers for Disease Control and Prevention (CDC) on the day of collection for measurement of drug levels.