Development and clinical assessment of new objective adherence markers for four microbicide delivery systems used in HIV prevention studies

Randomized controlled phase IIa clinical trial of safety, pharmacokinetics and pharmacodynamics of tenofovir and tenofovir plus levonorgestrel releasing intravaginal rings used by women in Kenya

Introduction

Globally, many young women face the overlapping burden of HIV infection and unintended pregnancy. Protection against both may benefit from safe and effective multipurpose prevention technologies.

Methods

Healthy women ages 18-34 years, not pregnant, seronegative for HIV and hepatitis B surface antigen, not using hormonal contraception, and at low risk for HIV were randomized 2:2:1 to continuous use of a tenofovir/levonorgestrel (TFV/LNG), TFV, or placebo intravaginal ring (IVR). In addition to assessing genital and systemic safety, we determined TFV concentrations in plasma and cervicovaginal fluid (CVF) and LNG levels in serum using tandem liquid chromatography-mass spectrometry. We further evaluated TFV pharmacodynamics (PD) through ex vivo CVF activity against both human immunodeficiency virus (HIV)-1 and herpes simplex virus (HSV)-2, and LNG PD using cervical mucus quality markers and serum progesterone for ovulation inhibition.

Results

Among 312 women screened, 27 were randomized to use one of the following IVRs: TFV/LNG (n = 11); TFV-only (n = 11); or placebo (n = 5). Most screening failures were due to vaginal infections. The median days of IVR use was 68 [interquartile range (IQR), 36-90]. Adverse events (AEs) were distributed similarly among the three arms. There were two non-product related AEs graded >2. No visible genital lesions were observed. Steady state geometric mean amount (ssGMA) of vaginal TFV was comparable in the TFV/LNG and TFV IVR groups, 43,988 ng/swab (95% CI, 31,232, 61,954) and 30337 ng/swab (95% CI, 18,152, 50,702), respectively. Plasma TFV steady state geometric mean concentration (ssGMC) was <10 ng/ml for both TFV IVRs. In vitro, CVF anti-HIV-1 activity showed increased HIV inhibition over baseline following TFV-eluting IVR use, from a median of 7.1% to 84.4% in TFV/LNG, 15.0% to 89.5% in TFV-only, and -27.1% to -20.1% in placebo participants. Similarly, anti-HSV-2 activity in CVF increased >50 fold after use of TFV-containing IVRs. LNG serum ssGMC was 241 pg/ml (95% CI 185, 314) with rapid rise after TFV/LNG IVR insertion and decline 24-hours post-removal (586 pg/ml [95% CI 473, 726] and 87 pg/ml [95% CI 64, 119], respectively).

Conclusion

TFV/LNG and TFV-only IVRs were safe and well tolerated among Kenyan women. Pharmacokinetics and markers of protection against HIV-1, HSV-2, and unintended pregnancy suggest the potential for clinical efficacy of the multipurpose TFV/LNG IVR.

Clinical Trial Registration

NCT03762382 [https://clinicaltrials.gov/ct2/show/NCT03762382].

Randomized, placebo controlled phase I trial of the safety, pharmacokinetics, pharmacodynamics and acceptability of a 90 day tenofovir plus levonorgestrel vaginal ring used continuously or cyclically in women: The CONRAD 138 study

Multipurpose prevention technologies (MPTs), which prevent sexually transmitted infection(s) and unintended pregnancy, are highly desirable to women. In this randomized, placebo-controlled, phase I study, women used a placebo or tenofovir (TFV) and levonorgestrel (LNG) intravaginal ring (IVR), either continuously or cyclically (three, 28-day cycles with a 3 day interruption in between each cycle), for 90 days. Sixty-eight women were screened; 47 were randomized to 4 arms: TFV/LNG or placebo IVRs used continuously or cyclically (4:4:1:1). Safety was assessed by adverse events and changes from baseline in mucosal histology and immune mediators. TFV concentrations were evaluated in multiple compartments. LNG concentration was determined in serum. Modeled TFV pharmacodynamic antiviral activity was evaluated in vaginal and rectal fluids and cervicovaginal tissue ex vivo. LNG pharmacodynamics was assessed with cervical mucus quality and anovulation. All IVRs were safe with no serious adverse events nor significant changes in genital tract histology, immune cell density or secreted soluble proteins from baseline. Median vaginal fluid TFV concentrations were >500 ng/mg throughout 90d. TFV-diphosphate tissue concentrations exceeded 1,000 fmol/mg within 72hrs of IVR insertion. Mean serum LNG concentrations exceeded 200 pg/mL within 2h of TFV/LNG use, decreasing quickly after IVR removal. Vaginal fluid of women using TFV-containing IVRs had significantly greater inhibitory activity (87-98% versus 10% at baseline; p<0.01) against HIV replication in vitro. There was a >10-fold reduction in HIV p24 antigen production from ectocervical tissues after TFV/LNG exposure. TFV/LNG IVR users had significantly higher rates of anovulation, lower Insler scores and poorer/abnormal cervical mucus sperm penetration. Most TFV/LNG IVR users reported no change in menstrual cycles or fewer days of and/or lighter bleeding. All IVRs were safe. Active rings delivered high TFV concentrations locally. LNG caused changes in cervical mucus, sperm penetration, and ovulation compatible with contraceptive efficacy. Trial registration: ClinicalTrials.gov #NCT03279120.

Genital Mucosal Drug Concentrations and anti-HIV Activity in Tenofovir-Based PrEP Products: Intravaginal Ring vs. Oral Administration

OBJECTIVE

To describe and compare systemic and local pharmacokinetics (PK) and cervicovaginal (CV) pharmacodynamics (PD) of oral tenofovir disoproxil fumarate (TDF) in combination with emtricitabine (FTC) with tenofovir (TFV) intravaginal ring (IVR).

DESIGN

Phase I, randomized, parallel-group study. Women (n = 22) used TDF/FTC oral tablets daily or TFV IVR continuously and were assessed at baseline and 14 days.

METHODS

TFV and FTC concentrations were measured in plasma, CV fluid (CVF), and CV tissue. TFV-diphosphate and FTC-triphosphate were assessed in CV tissue. In vitro PD antiviral activities of TFV and FTC (using in vivo concentration ranges) were modeled in the CVF and by infecting CV tissue explants ex vivo with HIV-1BaL.

RESULTS

Adverse events (AEs) were more common with oral TDF/FTC use (P < 0.01). The median CVF TFV concentrations were 106 ng/mL after use of TFV IVR vs. 102 ng/mL for TDF/FTC. The median TFV and TFV-diphosphate concentrations in CV tissue were >100-fold higher among IVR users. The median CVF FTC concentrations were 103 ng/mL. FTC and FTC-triphosphate were detected in all CV tissues from TDF/FTC users. HIV inhibitory activity of CVF increased significantly with treatment in both cohorts (P < 0.01) but was higher in TFV IVR users (P < 0.01). In vitro inhibition of tissue infection with ex vivo administration of TFV and FTC was dose dependent, with maximal efficacy achieved with 10 µg/mL TFV, 1 µg/mL FTC, and 0.1 µg/mL of TFV and FTC combined.

CONCLUSIONS

Both products were safe and increased mucosal HIV inhibitory activity. In addition to systemic protection, oral TDF/FTC displays a PK/PD profile compatible with CV mucosal antiviral activity. TFV IVR resulted in fewer AEs, lower TFV plasma concentrations, higher CVF and tissue TFV and TFV-DP concentrations, and greater anti-HIV activity in CVF.

Clinical testing of antiretroviral drugs as future prevention against vaginal and rectal transmission of HIV infection - a review of currently available results

The original purpose of vaginally applied microbicides was to slow down the HIV epidemic among the population until an effective vaccination was developed. Nowadays, antiretrovirals applied in the form of gels or vaginal rings are considered most prominent in this field and are tested via vaginal or, rarely, rectal applications in numerous clinical studies (9 different antiretroviral drugs in 33 clinical studies, especially in Africa). Only tenofovir (1 % gel) and dapivirine (25 mg in vaginal ring) progressed into the phase III clinical testing. Their efficiency depended on the user´s strict adherence to the application regimen (for tenofovir 54 %, for dapivirine 61 % in participants over 25 years of age). Despite this, they are expected to be important and effective tools of preventive medicine in the near future. This review summarizes the results obtained during long-term clinical testing (2005-2018) of antiretroviral drugs against vaginal and rectal transmission of HIV infection.