Drug-drug Interaction Study Between Bictegravir/Emtricitabine/Tenofovir Alafenamide and Feminizing Hormones in Trans Women Living With HIV

Transgender (trans) women have been found to be at higher risk of and to be disproportionally affected by HIV for multiple biologic and social reasons. Trans women living with HIV have also been found to have low usage and adherence rates to antiretroviral therapy (ART). Both healthcare providers and trans women, themselves, have expressed concerns of drug-drug interactions (DDIs) between ART drugs and feminizing hormones, which have in turn been shown to contribute to low rates of ART usage amongst trans women living with HIV. The objective of this DDI study is to investigate the pharmacokinetic effects of the common feminizing hormone regimens (oral estradiol with an anti-androgen (pharmaceutical and/or surgical and/or medical)) on the antiretroviral combination bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) and vice versa.

Methods and analysis: Participants will be assigned to three groups: group 1 will include 15 trans women living with HIV who are taking feminizing hormones and ART (investigational group); group 2 will include 15 premenopausal cis women living with HIV taking ART (ART control group); group 3 will include 15 trans women living without HIV taking feminizing hormones (hormone control group). Women living with HIV will have to be virally suppressed for at least three months and they will have to already be taking B/F/TAF or have their current ART regimen switched to B/F/TAF at baseline. Trans women participants will be required to be on 2 mg oral estradiol or higher and an anti-androgen (pharmaceutical, medical or surgical). Plasma ART drug concentrations will be sampled at the 2-month visit and compared among trans women living with HIV on feminizing hormones and premenopausal cis women living with HIV. Serum estradiol and total testosterone concentrations will be sampled at the baseline and month 2 visits and compared among trans women living with and without HIV. The primary endpoints are B/F/TAF pharmacokinetic parameters (Cmin, Cmax and AUC) between trans and cis women living with HIV at month 2 and the estradiol concentrations (Cmin, C4h, Cmax and AUC) and the proportions of the month 2 C4h that are within target (200 to 735 pmol/L) between trans women living with and without HIV at month 2. Other endpoints will include the mean estradiol and testosterone concentrations at baseline and the difference between baseline and month 2 estradiol pre-dose and C4h, satisfaction with feminizing hormones, HIV viral load, adherence, adverse events, patient-reported outcomes (i.e., symptoms), satisfaction with ART regimen and health status. If successful, this trial will serve to provide empirical evidence regarding a lack of, or presence of DDIs between B/F/TAF and feminizing hormones.

Dissemination: The findings will be disseminated through publication in peer-reviewed journals as well as presented at national and international conferences and community groups.