Safety and Pharmacokinetics (PK) of a Polyurethane Tenofovir Disoproxil Fumarate (TDF) Vaginal Ring

Overview

This prospective, randomized, single-blinded, placebo controlled trial will examine the safety and pharmacokinetics (PK) of a polyurethane tenofovir disoproxil fumarate (TDF) vaginal ring when used continuously for 14 consecutive days. The primary objective is to assess the safety of TDF vaginal rings when used continuously for 14 days by healthy, HIV-uninfected, sexually abstinent women, as compared with a placebo vaginal ring.

Tenofovir disoproxil fumarate (TDF) is a prodrug of TFV (tenofovir), an adenosine nucleoside monophosphonate (nucleotide) derivative with potent antiretroviral (ARV) activity. TDF permeates cells more rapidly than TFV resulting in increased intracellular accumulation of TFV-diphosphate (TFV-DP), the active metabolite. TDF is more potent than TFV and inhibits HIV-1 (Human Immunodeficiency Virus-1)and herpes simplex virus type 2 (HSV-2) infection in cell and tissue culture models at approximately 100-fold lower concentrations than TFV, suggesting that it may be an excellent candidate for prevention of HIV. TDF is licensed for the treatment of HIV-1 infection in the US, the European Union, Middle East, and Africa. The study will take place at the Albert Einstein College of Medicine in Bronx, New York, USA. Each participant will receive an IVR (intravaginal ring) containing TDF or a placebo ring. The vaginal ring will be worn continuously for 14 days. It will be inserted into the vagina following cessation of participant's menses, by the study clinician at Visit 3 and removed by the study clinician at Visit 7. Each participant will be followed for 7 days following ring removal. It is hypothesized that both the TDF IVR and placebo IVR will be safe and well tolerated among healthy, sexually abstinent women on combined-hormonal contraception. The null hypothesis is that there will be no difference in the safety profile between the active product and the placebo. Careful assessments of safety, including systemic and genital tract, will be undertaken with special consideration for issues related to irritation and systemic toxicity. The design of the study will allow safety comparisons of TDF ring to a placebo ring. A 14-day safety and PK study is proposed for this first-in-human study per FDA (For and Drug Administration) guidance. The study duration was carefully selected to control risk to the study participants. TFV 1% vaginal gel has been extensively tested in clinical trials at higher doses (8-fold dose margin) than the predicted dose delivered by the TDF IVR-001 study, and the TFV gel showed no significant adverse events at this higher dose in thousands of women. Given the drug release kinetics observed in vitro and in NHP (non-human primate) studies, TDF and TFV (formed following hydrolysis of the prodrug TDF) concentrations in cervicovaginal fluid (CVF) are expected to reach steady state within a few days and maintain steady state concentrations for the duration of the planned 14 days of ring use. Sampling at multiple time points and sites (vaginal, cervical, rectal and blood) will provide information on drug distribution, kinetics, and, by sampling after ring removal on Day 14, how long drug persists. The latter may be important as behavior studies suggest that some women may remove a ring at time of menses or around sex. To capture systemic absorption, blood will be sampled to determine drug concentrations in blood plasma and PBMCs (peripheral blood mononuclear cells). To capture the concentrations of drug within the genital tract, CVF will be sampled using Dacron swabs of the introitus, ectocervix, and area adjacent to the ring. Rectal sampling with swabs will also be obtained if participants consent to the procedure to determine drug concentrations in the rectum. Sampling at different sites (proximal and distal to the ring) will provide important information as to how well drug permeates throughout the genital tract. Cervical tissue sampling will be highly informative given that it is the likely site of drug action. However, biopsies must be taken sparingly for several reasons: they are uncomfortable to some and alter the healing process. Accordingly, two baseline biopsies will be taken prior to randomization and ring insertion to confirm absence of study drug and for PD studies. Subsequent biopsies for PK (pharmacokinetics) and PD (pharmacodynamics) studies will be delayed until the ring is removed. Following TDF IVR removal a third biopsy will be obtained for PK studies. Two cervical biopsies will be obtained following placebo IVR removal for PD studies and to blind safety data. The study will not be double-blinded because the TDF and placebo rings are not identical in appearance. Therefore, the study clinician will be able to collect two biopsies from participants in the placebo group and three biopsies from participants in the TDF ring group after ring removal. In order to maintain participant blinding, all participants will be informed that two biopsies will be taken before ring insertion and 2-3 biopsies will be taken after ring removal. Paired biopsies will provide the best data, as it will avoid inter-individual variability; both sets of cervical biopsies (pre- and post-IVR use) will be obtained during the second half of the participant's menstrual cycle (cycle days 18-23), which is prior to menses. Cervical biopsies will be obtained without local anesthetic. Participants may take acetaminophen before and/or after the biopsies are collected if desired. Primary Objective: • Assess the safety of TDF IVR when used continuously for 14 days by healthy, HIV-uninfected, sexually abstinent women, as compared with the placebo IVR Secondary Objective: • Examine systemic and genital tract PK of TDF release during and after 14 days of continuous use of a reservoir-type IVR containing TDF Exploratory Objectives: * Evaluate the acceptability of and adherence to the study IVR * Evaluate the PD during and after 14 days of continuous use of a reservoir-type IVR containing TDF by measuring the antiviral activity of genital tract secretions ex vivo and challenging biopsy tissue with virus * Examine the impact of the study IVR on genital tract mucosal immunity and the vaginal microbiota * Examine the PK of TDF and TFV in rectal fluid during and after 14 days of continuous use of a reservoir-type TDF IVR * Evaluate mechanical properties and drug content following 14 days of continuous use of reservoir-type IVRs This is a single-site, two-arm, randomized single-blind, placebo-controlled trial. The study population will include approximately 30 healthy, 18-45 year old women who are HIV-uninfected, non-pregnant, sexually abstinent and using adequate contraception, as described in the protocol. This sample size was chosen with the goal of having 12 women per group complete the study and includes additional women to account for participants who may not complete the study or are lost to follow-up. Only female volunteers will be recruited since an IVR can only be used by women and the endpoints require genital sampling. To ensure participants are protected from pregnancy during study participation, to minimize variability among contraceptive methods, and to ensure adequate time between menses for ring use and sample collection, all volunteers must be using low-dose combined hormonal contraceptive pills. As this is a first-in-human trial of an intravaginal TDF ring, only healthy women will be recruited and will be asked to wear a TDF or placebo IVR for 14 days. The approximate time to complete study enrollment is expected to be 9 months. Two study groups are planned. Both groups will be assigned to complete a total of 9 study visits: (Screening \[Visit 1\], Enrollment \[Visit 2\], Days 0 \[Visit 3\], 1 \[Visit 4\], 3-5 \[Visit 5\], 7 \[Visit 6\], 14 \[Visit 7\], 16-18 \[Visit 8\], 21 \[visit 9\]). A Safety Call will also be conducted on Day 10 of the study. The two study groups are: 1. Reservoir-type TDF IVR group; 2. Reservoir-type polyurethane IVR group; The expected duration for participants is approximately 5 - 10 weeks (including a screening visit, an enrollment visit, two weeks of continuous IVR use, and one week following IVR removal). Participants will undergo Visit 2 within 45 days of screening. No study data will be collected after the Final Study/Early Termination Visit unless the participant is pregnant at the Final Study/Early Termination Visit. Participants who have AEs (adverse events) at the Final Study/Early Termination Visit that have not resolved or stabilized will be followed beyond the Final Study/Early Termination Visit until a clinically acceptable resolution of the AE(s) is confirmed and documented. Clinical acceptability of resolution will be determined by the PL (Program Leader) in consultation with the Protocol Safety Review Team (PSRT). Participants who are pregnant at the Final Study/Early Termination Visit may be followed in accordance with procedures described in the study protocol.

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