Haaland RE, et al. - Researchers examined urine and blood collected from 34 HIV-negative men who have sex with men aged 18–49 years, enrolled in a clinical trial comparing two antiretroviral regimens, in order to assess whether urine could afford a biomarker of adherence for currently approved preexposure prophylaxis and HIV treatment regimens. Specimen collection was performed at 4 and 24 hours after a single oral dose of tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) (n = 10) or tenofovir alafenamide (TAF)/FTC/cobicistat (COBI)/elvitegravir (EVG) (n = 8), or following 4 and 10 days of daily oral TDF/FTC (n = 9) or TAF/FTC/COBI/EVG (n = 7). Based on outcomes, they suggest a possible utility of high urine FTC and TFV concentrations in rendering indication of adherence to daily oral dosing with TDF or TAF-based regimens used for treatment and prevention.