Safety and pharmacokinetics of single, dual, and triple antiretroviral drug formulations delivered by pod-intravaginal rings designed for HIV-1 prevention: A Phase I trial

Abstract

Background: Intravaginal rings (IVRs) for HIV pre-exposure prophylaxis (PrEP) theoretically overcome some adherence concerns associated with frequent dosing that can occur with oral or vaginal film/gel regimens. An innovative pod-IVR, composed of an elastomer scaffold that can hold up to 10 polymer-coated drug cores (or "pods"), is distinct from other IVR designs as drug release from each pod can be controlled independently. A pod-IVR has been developed for the delivery of tenofovir (TFV) disoproxil fumarate (TDF) in combination with emtricitabine (FTC), as daily oral TDF-FTC is the only Food and Drug Administration (FDA)-approved regimen for HIV PrEP. A triple combination IVR building on this platform and delivering TDF-FTC along with the antiretroviral (ARV) agent maraviroc (MVC) also is under development.

Methodology and findings: This pilot Phase I trial conducted between June 23, 2015, and July 15, 2016, evaluated the safety, pharmacokinetics (PKs), and acceptability of pod-IVRs delivering 3 different ARV regimens: 1) TDF only, 2) TDF-FTC, and 3) TDF-FTC-MVC over 7 d. The crossover, open-label portion of the trial (N = 6) consisted of 7 d of continuous TDF pod-IVR use, a wash-out phase, and 7 d of continuous TDF-FTC pod-IVR use. After a 3-mo pause to evaluate safety and PK of the TDF and TDF-FTC pod-IVRs, TDF-FTC-MVC pod-IVRs (N = 6) were evaluated over 7 d of continuous use. Safety was assessed by adverse events (AEs), colposcopy, and culture-independent analysis of the vaginal microbiome (VMB). Drug and drug metabolite concentrations in plasma, cervicovaginal fluids (CVFs), cervicovaginal lavages (CVLs), and vaginal tissue (VT) biopsies were determined via liquid chromatographic-tandem mass spectrometry (LC-MS/MS). Perceptibility and acceptability were assessed by surveys and interviews. Median participant age was as follows: TDF/TDF-FTC group, 26 y (range 24-35 y), 2 White, 2 Hispanic, and 2 African American; TDF-FTC-MVC group, 24.5 y (range 21-41 y), 3 White, 1 Hispanic, and 2 African American. Reported acceptability was high for all 3 products, and pod-IVR use was confirmed by residual drug levels in used IVRs. There were no serious adverse events (SAEs) during the study. There were 26 AEs reported during TDF/TDF-FTC IVR use (itching, discharge, discomfort), with no differences between TDF alone or in combination with FTC observed. In the TDF-FTC-MVC IVR group, there were 12 AEs (itching, discharge, discomfort) during IVR use regardless of attribution to study product. No epithelial disruption/thinning was seen by colposcopy, and no systematic VMB shifts were observed. Median (IQR) tenofovir diphosphate (TFV-DP) tissue concentrations of 303 (277-938) fmol/10(6) cells (TDF), 289 (110-603) fmol/10(6) cells (TDF-FTC), and 302 (177.1-823.8) fmol/10(6) cells (TDF-FTC-MVC) were sustained for 7 d, exceeding theoretical target concentrations for vaginal HIV prevention. The study's main limitations include the small sample size, short duration (7 d versus 28 d), and the lack of FTC triphosphate measurements in VT biopsies.

Conclusions: An innovative pod-IVR delivery device with 3 different formulations delivering different regimens of ARV drugs vaginally appeared to be safe and acceptable and provided drug concentrations in CVFs and tissues exceeding concentrations achieved by highly protective oral dosing, suggesting that efficacy for vaginal HIV PrEP is achievable. These results show that an alternate, more adherence-independent, longer-acting prevention device based on the only FDA-approved PrEP combination regimen can be advanced to safety and efficacy testing.

Trial registration: ClinicalTrials.gov NCT02431273.

Conflict of interest statement

I have read the journal's policy and the authors of this manuscript have the following competing interests: During part of the time of the study, IB, SAC, and JMC were employees of Auritec and participated in manufacturing the vaginal rings; they were no longer employees at the time of sample collection, data analysis, and manuscript preparation. Prior to August 2016, MG was a 50% shared employee of Auritec and participated in the residual drug measurements and coordinating sample distribution. JAM and MMB are co-inventors on patent applications that include aspects of the intravaginal ring device that was used in the clinical trial described in this manuscript and have received funding for preclinical research relevant to HIV (but not vaginal rings) from ViiV/GSK. They also have received funding from the International Partnership for Microbicides, CONRAD, and the Population Council. JAM, MMB, and MG are co-inventors on the following patent applications relevant to HIV: https://patents.google.com/patent/WO2016149561A1/en and https://patents.google.com/patent/WO2017161136A1/en. KLV and RBP are paid consultants to ABL, Inc. CWH has received funding for clinical research from ViiV/GSK managed via Johns Hopkins University and was a consultant for 1-2 days in 2017 to ViiV/GSK.

Figures

Fig 1. CVF drug levels and washout following TDF pod-IVR use.

ARV drug levels in CVF fall off rapidly following IVR removal (grey arrow) but are quantifiable for a further 2 wk. Every circular datum represents an individual sample from one of the participants (n = 6), while triangles depict samples that were BLQ of the analytical method, and values were calculated as follows: [(assay BLQ)/2]/(median swab mass). (A) TDF. (B) TFV. (C) Box plots of ARV drug terminal half-lives of elimination from CVF. The box extends from the 25th to 75th percentiles, with the horizontal line in the box representing the median; whiskers represent the lowest and highest datum. Comparison of the TDF and TFV groups using an unpaired t test with Welch’s correction showed that the groups were significantly different (P = 0.0053). ARV, antiretroviral; BLQ, below the lower limit of quantitation; CVF, cervicovaginal fluid; IVR, intravaginal ring; TDF, tenofovir disoproxil fumarate; TFV, tenofovir.

Fig 2. CVF drug levels and washout following TDF-FTC pod-IVR use.

ARV drug levels in CVF fall off rapidly following IVR removal (grey arrow) but are quantifiable for a further 2 wk. Every circular datum represents an individual sample from one of the participants (n = 6), while triangles depict samples that were BLQ of the analytical method, and values were calculated as follows: [(assay BLQ)/2]/(median swab mass). (A) TDF. (B) TFV. (C) FTC. (D) Box plots of ARV drug terminal half-lives of elimination from CVF. The box extends from the 25th to 75th percentiles, with the horizontal line in the box representing the median; whiskers represent the lowest and highest datum. Comparison of the TDF and TFV groups using an unpaired t test with Welch’s correction showed that the groups were significantly different (P = 0.0131). ARV, antiretroviral; BLQ, below the lower limit of quantitation; CVF, cervicovaginal fluid; FTC, emtricitabine; IVR, intravaginal ring; TDF, tenofovir disoproxil fumarate; TFV, tenofovir.

Fig 3. CVF drug levels and washout following TDF-FTC-MVC pod-IVR use.

ARV drug levels in CVFs fall off rapidly following IVR removal (grey arrows) but are quantifiable for a further 2 wk. Every circular datum represents an individual sample from one of the participants (n = 6), while triangles depict samples that were BLQ of the analytical method, and values were calculated as follows: [(assay BLQ)/2]/(median swab mass). (A) TDF. (B) TFV. (C) FTC. (D) MVC. (E) Box plots of ARV drug terminal half-lives of elimination from CVF. The box extends from the 25th to 75th percentiles, with the horizontal line in the box representing the median; whiskers represent the lowest and highest datum. Comparison of the TDF, FTC, and MVC groups using an ordinary 1-way ANOVA analysis (no matching or pairing of the data) showed that they were not significantly different (P = 0.8973). However, comparison of the TDF and TFV groups using an unpaired t test with Welch’s correction, showed that the groups were significantly different (P = 0.0327). ANOVA, analysis of variance; ARV, antiretroviral; BLQ, below the lower limit of quantitation; CVF, cervicovaginal fluid; FTC, emtricitabine; IVR, intravaginal ring; MVC, maraviroc; TDF, tenofovir disoproxil fumarate; TFV, tenofovir.

Fig 4. Drug and drug metabolite exposure in VT at TDF and TDF-FTC pod-IVR removal (Day 7).

(A) ARV drug and TFV-DP levels in vaginal biopsies collected on Day 7 within 30 min of pod-IVR removal. Analyte concentrations are all expressed as fmol/mg of tissue homogenate to allow meaningful cross-comparison. Every circular datum represents an individual sample from one of the participants (n = 6); horizontal lines represent group medians; blue, TFV; green, TFV-DP; red, FTC. (B) Paired CVF:VT concentration ratios of TFV (molar sum of TDF and TFV concentrations) and FTC at Day 7; horizontal lines represent group means. The ratios provide a measure of the extent of tissue penetration for each analyte following vaginal delivery and, hence, vaginal bioavailability. The CVF TFV concentrations used in this calculation were the molar sum of the measured TFV and TDF concentrations as the prodrug hydrolyzes to TFV in the vaginal mucosa. ARV, antiretroviral; CVF, cervicovaginal fluid; FTC, emtricitabine; IVR, intravaginal ring; TDF, tenofovir disoproxil fumarate; TFV, tenofovir; TFV-DP, tenofovir diphosphate; VT, vaginal tissue.

Fig 5. Drug and drug metabolite exposure in VTs at TDF-FTC-MVC pod-IVR removal (Day 7).

(A) ARV drug and TFV-DP levels in vaginal biopsies collected on Day 7 within 30 min of pod-IVR removal. Analyte concentrations are all expressed as fmol/mg of tissue homogenate to allow meaningful cross-comparison. Every circular datum represents an individual sample from one of the participants (n = 6), while inverted triangles depict samples that were ALQ of the analytical method, and values were calculated as follows: (assay ALQ)/(median biopsy mass); horizontal lines represent group medians. (B) Paired CVF:VT concentration ratios of total TFV (molar sum of TDF and TFV concentrations), FTC, and MVC at Day 7; horizontal lines represent group means. The ratios describe the extent of tissue penetration for each analyte following vaginal delivery and, hence, vaginal bioavailability. The CVF TFV concentrations used in this calculation were the molar sum of the measured TFV and TDF concentrations, as the prodrug hydrolyzes to TFV in the vaginal mucosa. The two MVC VT samples that were ALQ were omitted from the analysis. There was no statistically significant difference between the three groups according to an unpaired, nonparametric Kruskal–Wallis test (P = 0.1591). ALQ, above the upper limit of quantitation; ARV, antiretroviral; CVF, cervicovaginal fluid; FTC, emtricitabine; IVR, intravaginal ring; MVC, maraviroc; TDF, tenofovir disoproxil fumarate; TFV, tenofovir; TFV-DP, tenofovir diphosphate; VT, vaginal tissue.