Depot Medroxyprogesterone Acetate and the Vaginal Microbiome as Modifiers of Tenofovir Diphosphate and Lamivudine Triphosphate Concentrations in the Female Genital Tract of Ugandan Women: Implications for Tenofovir Disoproxil Fumarate/Lamivudine in Preexposure Prophylaxis

Drug-drug interactions between antiretrovirals and hormonal contraception: An updated systematic review

OBJECTIVE

To summarize and update information regarding drug-drug interactions (DDIs) between antiretrovirals (ARVs) and hormonal contraceptives (HCs).

STUDY DESIGN

Systematic review.

RESULTS

We included 49 articles, with clinical, ARV, or HC PK outcomes reported by 39, 25, and 30 articles, respectively, with some articles reporting outcomes in two or more categories. Fifteen of 18 articles assessing DDIs between efavirenz and progestin implants, emergency contraception, or combined hormonal intravaginal rings found higher pregnancy rates, luteal progesterone levels suggesting ovulation, or reduced progestin PK values. Five studies documented that CYP2B6 single nucleotide polymorphisms exacerbated this DDI. One cohort detected doubled bone density loss with concomitant depot medroxyprogesterone acetate (DMPA) and tenofovir disoproxil fumarate (TDF)-containing ART use versus TDF alone. No other studies described DDIs impacting clinical outcomes. Few adverse events were attributed to ARV-HC use with none exceeding Grade 2. Evidence quality was generally moderate, with dis-similar treatment and control groups, identifying and controlling for confounding, and minimizing attrition bias in the study design being the most frequent limitations.

CONCLUSION

TDF-DMPA DDIs warrant longer-term study on bone health and consideration of alternate combinations. For efavirenz-based ART, client counseling on relative risks, including both potential increase in pregnancy rate with concomitant efavirenz and implant use and lower pregnancy rates compared to other HCs even with concomitant efavirenz use, should continue to allow users comprehensive method choice.

IMPLICATIONS

Most ARVs and HCs may be used safely and effectively together. Efavirenz-based ART requires careful counseling and data for possible interactions between HCs and new ARV classes are anticipated.

Cell and Tissue Specific Metabolism of Nucleoside and Nucleotide Drugs: Case Studies and Implications for Precision Medicine

Many clinically used antiviral drugs are nucleoside or nucleotide analog drugs, which have a unique mechanism of action that requires intracellular phosphorylation. This dependence on intracellular activation presents novel challenges for the discovery and development of nucleoside/nucleotide analog drugs. Contrary to many small molecule drug development programs that rely on plasma pharmacokinetics and systemic exposures, the precise mechanisms that result in efficacious intracellular nucleoside triphosphate concentrations must be understood in the process of nucleoside/nucleotide drug development. The importance is highlighted here, using the following as case studies: the herpes treatment acyclovir, the cytomegalovirus therapy ganciclovir, and human immunodeficiency virus (HIV) treatments based on tenofovir, which are also in use for HIV prophylaxis. For each drug, the specificity of metabolism that results in its activation in different cells or tissues is discussed, and the implications explored. Acyclovir's dependence on a viral enzyme for activation provides selective pressure for resistance mutations. Ganciclovir is also dependent on a viral enzyme for activation, and suicide gene therapy capitalizes on that for a novel oncology treatment. The tissue of most relevance for tenofovir activation depends on its use as treatment or as prophylaxis, and the pharmacogenomics and drug-drug interactions in those tissues must be considered. Finally, differential metabolism of different tenofovir prodrugs and its effects on toxicity risk are explored. Taken together, these examples highlight the importance of understanding tissue specific metabolism for optimal use of nucleoside/nucleotide drugs in the clinic. SIGNIFICANCE STATEMENT: Nucleoside and nucleotide analogue drugs are cornerstones in current antiviral therapy and prevention efforts that require intracellular phosphorylation for activity. Understanding their cell and tissue specific metabolism enables their rational, precision use for maximum efficacy.

Interaction of Depot Medroxyprogesterone Acetate and Tenofovir Disoproxil Fumarate/Emtricitabine on Peripheral Blood Mononuclear Cells and Cervical Tissue Susceptibility to HIV Infection and Pharmacokinetics

BACKGROUND

Depot medroxyprogesterone acetate (DMPA) is a widely used contraceptive method. HIV pre-exposure prophylaxis with emtricitabine and tenofovir disoproxil fumarate (F/TDF) is highly effective in reducing HIV acquisition in women. We sought to determine the impact of DMPA on F/TDF pharmacokinetics and pharmacodynamics.

METHODS

Twelve healthy premenopausal cisgender women were enrolled and each completed 4 sequential conditions: (1) baseline, (2) steady-state F/TDF alone, (3) steady-state F/TDF + DMPA, and (4) DMPA alone. Assessments included clinical, pharmacokinetic, viral infectivity (ex vivo challenge of peripheral blood mononuclear cells by X4- and R5-tropic green fluorescent protein pseudoviruses and cervical tissue by HIV BaL ), endocrine, immune cell phenotyping, and renal function.

RESULTS

Compared with baseline, F/TDF (± DMPA) significantly decreased both %R5- and X4-infected CD4 T cells and F/TDF + DMPA decreased cervical explant p24 (all P < 0.05). The %R5- and X4-infected CD4 T cells were higher during DMPA alone than during F/TDF periods and lower than baseline (not statistically significant). Cervical explant p24 fell between baseline and F/TDF values (not statistically significant). There were neither statistically significant differences in F/TDF pharmacokinetics, including total or renal clearance of either antiviral drug, nor changes in glomerular filtration rate with the addition of DMPA. There were few immune cell phenotypic differences across conditions.

CONCLUSIONS

F/TDF decreased HIV infection in both challenge assays, whereas DMPA alone did not enhance HIV infection in either challenge assay. DMPA did not alter F/TDF pharmacokinetics or renal function.

Expression, Activity, and Regulation of Phosphorylating Enzymes in Tissues and Cells Relevant to HIV-1 Sexual Transmission

Phosphorylating enzymes (PEs) are responsible for activating nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) such as tenofovir (TFV) and are critical for their conversion to obtain intracellular antiviral activity. However, there are limited data available regarding the expression of PEs and their activity in the female genital tract. This work compared the messenger RNA (mRNA) expression levels of PEs in human female genital tissue, immune cells, and animal models that are commonly used in human immunodeficiency virus (HIV) research. Furthermore, the effect of contraceptive hormones and proinflammatory cytokines on tenofovir diphosphate (TFV-DP) formation and efficacy in human vaginal, epithelial, and immune cells was also evaluated. We found that human vaginal and ectocervical tissues had similar mRNA expression for seven PEs tested. Polymerase chain reaction results revealed that creatine kinase brain (CKB), mitochondrial creatine kinase 1 (CKMT1), mitochondrial creatine kinase 2 (CKMT2), adenylate kinase AK3L1 (AK4), and nucleoside diphosphate kinase 1 (NME1) exhibited a 10- to 10,000-fold higher expression level in a vaginal epithelial cell line, VK2, compared with CD4⁺ T cells (p < .05). Medroxyprogesterone acetate (MPA)/progesterone (P4) and IL-1β/IL-8 treatment resulted in altered TFV-DP levels in VK2 and PM1 cells. MPA and P4 at concentrations above 0.1 μM, as well as IL-1β and IL-8 at concentrations above 10 ng/mL, significantly decreased HIV-1_BaL inhibition in PM1 cells when 1 μM TFV was added. However, this observed effect of hormones and cytokines was abrogated when TFV concentration was raised to 1 mM. These in vitro results elucidate the role of PEs in TFV metabolism and provide information regarding differences in PE tissue expression for animal models commonly used in HIV testing. This information can be applied to better understand and interpret data obtained using these models.

Higher colorectal tissue HIV infectivity in cisgender women compared with MSM before and during oral preexposure prophylaxis

OBJECTIVE

The objective of this study was to compare HIV-negative cisgender women (CGW) with MSM for mucosal tissue differences in pharmacokinetics, HIV infectivity and cell phenotype.

DESIGN

A substudy of HPTN 069/ACTG A5305, 48-week study of three oral candidate preexposure prophylaxis regimens: maraviroc, maraviroc/emtricitabine and maraviroc/tenofovir disoproxil fumarate (TDF) compared with a TDF/emtricitabine control group.

METHODS

Plasma, peripheral blood mononuclear cells and cervical and colorectal tissue biopsies were collected at Baseline (no drug), Week 24 and 48 (on drug), and Week 49 (1-week postdrug). Drug concentrations were assessed in all matrices. HIV infectivity was assessed using tissue biopsy 'explants' challenged with HIV ex vivo followed by HIV p24 measurement. Flow cytometry evaluated colorectal cell phenotype.

RESULTS

Thirty-seven CGW and 54 MSM participated. CGW's colorectal explant p24 was higher than MSM before (0.31 log10, P = 0.046), during (1.01-1.19 log10, P = 0.016) and one week after (0.61 log10, P = 0.011) study drug dosing. Pooling regimens, cervical explant p24 did not differ among visits. CGW had higher plasma maraviroc and colorectal tissue tenofovir diphosphate and lower colorectal tissue emtricitabine (all P < 0.005) compared with MSM. Each study drug's cervical tissue concentrations were more than 10-fold below paired colorectal concentrations (P < 0.001). Cell phenotype sex differences included 4% higher CD38+/CD8+ cells at baseline and 3-7% higher CD69+/CD8+ cells throughout Weeks 24-49 in CGW compared with MSM (P < 0.05).

CONCLUSION

Colorectal explants in CGW demonstrated greater HIV infectivity than MSM with and without study drugs. Small differences in adherence, drug concentration and colorectal tissue flow cytometry cannot fully explain this difference.

The effect of different contraceptive methods on the vaginal microbiome

Introduction: Following a historical overview, the effect of different contraceptive methods on vaginal microbiome has been reviewed and summarized.Areas covered: Effects of combined hormonal contraceptives (oral or vaginal) and of progestin only (injectable and implantable), intrauterine devices/systems (copper- or levonorgestrel-releasing), on vaginal microbiome. In addition, mention is made of vaginal rings releasing antiviral drugs and lactic acid.Expert opinion: The vaginal microbiota (VM) is unique in that it is normally dominated by Lactobacillus species providing a degree of protection against infections; this however may vary, depending on the species and strains of Lactobacillus. Bacterial Vaginosis represents the most common dysbiosis of the VM and its prevalence can be influenced by use of contraception. Available evidence indicates that, under the influence of oral or systemically administered female sex hormones, there is apromotion of vaginal eubiosis, with aprevalence of ahealthy VM in which Lactobacilli predominate.

The effect of depot medroxyprogesterone acetate on tenofovir alafenamide in rhesus macaques

Prevention of HIV infection and unintended pregnancies are public health priorities. In sub-Saharan Africa, where HIV prevalence is highest, depot medroxyprogesterone acetate (DMPA) is widely used as contraception. Therefore, understanding potential interactions between DMPA and antiretrovirals is critical. Here, we use a macaque model to investigate the effect of DMPA on the pharmacology of the antiretroviral tenofovir alafenamide (TAF). Female rhesus macaques received 30 mg of DMPA (n = 9) or were untreated (n = 9). Macaques received a human equivalent dose of TAF (1.5 mg/kg) orally by gavage. Tenofovir (TFV) and TFV-diphosphate (TFV-DP) were measured in blood, secretions, and tissues over 72 h. The median area under the curve (AUC_0-72h) values for TFV-DP in peripheral blood mononuclear cells were similar in DMPA-treated (6991 fmol*h/10⁶ cells) and untreated controls (5256 fmol*h/10⁶ cells) (P = 0.174). Rectal tissue TFV-DP concentrations from DMPA+ animals [median: 20.23 fmol/mg of tissue (range: 4.94-107.95)] were higher than the DMPA- group [median: below the limit of quantification (BLOQ-11.92)], (P = 0.019). TFV-DP was not detectable in vaginal tissue from either group. A high-dose DMPA treatment in macaques was associated with increased rectal TFV-DP levels, indicating a potential tissue-specific drug-drug interaction. The lack of detectable TFV-DP in the vaginal tissue warrants further investigation of PrEP efficacy with single-agent TAF products. DMPA did not affect systemic TAF metabolism, with similar PBMC TFV-DP in both groups, suggesting that DMPA use should not alter the antiviral activity of TAF.

Pharmacokinetic and Pharmacodynamic Impacts of Depot Medroxyprogesterone Acetate Use on HIV Pre-exposure Prophylaxis in Women

BACKGROUND

Depot medroxyprogesterone acetate (DMPA) is a commonly used contraceptive in areas where use of tenofovir disoproxil fumarate and emtricitabine for HIV pre-exposure prophylaxis (PrEP) is increasing.

OBJECTIVES

We aimed to investigate the impact of DMPA on PrEP drug pharmacokinetics and pharmacodynamics in women using PrEP before and after DMPA administration.

METHODS

In this pilot study, 12 HIV-negative women ages 18-45 underwent biological sample collection at 3 time points: before study drug, after 2 weeks of daily PrEP use alone, and after 2 weeks of daily PrEP and concomitant DMPA use. We measured drug and drug metabolites in plasma, peripheral blood mononuclear cells, cervicovaginal fluid, cervical tissue, and rectal fluid after each 2-week course of PrEP. We measured HIV replication ex vivo in genital tissue biopsies and innate anti-HIV activity in cervicovaginal fluid before PrEP and after both courses. We compared drug concentrations after PrEP alone to after PrEP and DMPA in the same participant using Wilcoxon signed-rank tests. We used mixed effects linear regression models to compare pharmacodynamic measures for each participant at predrug baseline, after PrEP alone, and after PrEP and DMPA.

RESULTS

We found no significant differences in PrEP drug and drug metabolite concentrations in any compartment during concomitant DMPA use compared with use of PrEP alone, except for a reduction in emtricitabine concentration in cervical tissue. We found no difference in HIV replication in cervical tissue or anti-HIV activity in cervicovaginal fluid during concomitant DMPA and PrEP use compared with during PrEP use alone.

CONCLUSIONS

Concomitant use of DMPA does not clinically alter pharmacokinetics or pharmacodynamics of PrEP in women. These data support the safety of DMPA use in women using PrEP.

Safety and continued use of the levonorgestrel intrauterine system as compared with the copper intrauterine device among women living with HIV in South Africa: A randomized controlled trial

BACKGROUND

Women living with HIV (WLHIV) have lower rates of contraceptive use than noninfected peers, yet concerns regarding contraceptive efficacy and interaction with antiretroviral therapy (ART) complicate counseling. Hormonal contraceptives may increase genital tract HIV viral load (gVL) and sexual transmission risk to male partners. We compared gVL, plasma VL (pVL), and intrauterine contraceptive (IUC) continuation between the levonorgestrel intrauterine system (LNG-IUS) and copper intrauterine device (C-IUD) in Cape Town, South Africa.

METHODS AND FINDINGS

In this double-masked, randomized controlled noninferiority trial, eligible WLHIV were ages 18-40, not pregnant or desiring pregnancy within 30 months, screened and treated (as indicated) for reproductive tract infections (RTIs) within 1 month of enrollment, and virologically suppressed using ART or above treatment threshold at enrollment (non-ART). Between October 2013, and December 2016, we randomized consenting women within ART groups, using 1:1 permuted block randomization stratified by ART use, age (18-23, 24-31, 32-40), and recent injectable progestin contraceptive (IPC) exposure, and provided the allocated IUC. At all visits, participants provided specimens for gVL (primary outcome), pVL, RTI, and pregnancy testing. We assessed gVL and pVL across 6 and 24 months controlling for enrollment measures, ART group, age, and RTI using generalized estimating equation and generalized linear models (non-ART group pVL and hemoglobin) in as-treated analyses. We measured IUC discontinuation rates with Kaplan-Meier estimates and Cox proportional hazards models. We enrolled 71 non-ART (36 LNG-IUS, 31 C-IUD; 2 declined and 2 were ineligible) and 134 ART-using (65 LNG-IUS, 67 C-IUD; 1 declined and 1 could not complete IUC insertion) women. Participant median age was 31 years, and 95% had 1 or more prior pregnancies. Proportions of women with detectable gVL were not significantly different comparing LNG-IUS to C-IUD across 6 (adjusted odds ratio [AOR]: 0.78, 95% confidence interval [CI] 0.44-1.38, p = 0.39) and 24 months (AOR: 1.03, 95% CI: 0.68-1.57, p = 0.88). Among ART users, proportions with detectable pVL were not significantly different at 6 (AOR = 0.83, 95% CI 0.37-1.86, p = 0.65) and 24 months (AOR = 0.94, 95% CI 0.49-1.81, p = 0.85), whereas among non-ART women, mean pVL was not significantly different at 6 months (-0.10 log10 copies/mL, 95% CI -0.29 to 0.10, p = 0.50) between LNG-IUS and C-IUD users. IUC continuation was 78% overall; C-IUD users experienced significantly higher expulsion (8% versus 1%, p = 0.02) and elective discontinuation (adjusted hazard ratio: 8.75, 95% CI 3.08-24.8, p < 0.001) rates. Sensitivity analysis adjusted for differential IUC discontinuation found similar gVL results. There were 39 serious adverse events (SAEs); SAEs believed to be directly related to IUC use (n = 7) comprised 3 pelvic inflammatory disease (PID) cases and 4 pregnancies with IUC in place with no discernible trend by IUC arm. Mean hemoglobin change was significantly higher among LNG-IUS users across 6 (0.57 g/dL, 95% CI 0.24-0.90; p < 0.001) and 24 months (0.71 g/dL, 95% CI 0.47-0.95; p < 0.001). Limitations included not achieving non-ART group sample size following change in ART treatment guidelines and truncated 24 months' outcome data, as 17 women were not yet eligible for their 24-month visit at study closure. Also, a change in VL assay during the study may have caused some discrepancy in VL values because of different limits of detection.

CONCLUSIONS

In this study, we found that the LNG-IUS did not increase gVL or pVL and had low levels of contraceptive failure and associated PID compared with the C-IUD among WLHIV. LNG-IUS users were significantly more likely to continue IUC use and had higher hemoglobin levels over time. The LNG-IUS appears to be a safe contraceptive with regard to HIV disease and may be a highly acceptable option for WLHIV.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01721798.

Topical Microbicides in HIV Prevention: State of the Promise

HIV topical microbicides are products with anti-HIV activity, generally incorporating a direct-acting antiretroviral agent, that when applied to the vagina or rectum have the potential to prevent the sexual acquisition of HIV in women and men. Topical microbicides may meet the prevention needs of individuals and groups for whom oral daily forms of pre-exposure prophylaxis (PrEP) have not been acceptable. Microbicides can provide personal control over HIV prevention and offer the possibility of discreet use, qualities that may be particularly important for receptive partners in sexual relationships such as women and transgender women and men, who together account for the clear majority of new HIV infections worldwide. Although the promise of such a product emerged nearly three decades ago, proof of concept has been demonstrated only within the last decade. A robust pipeline of microbicidal gels, films, inserts, and rings has been evaluated in multiple studies among at-risk women and men, and refinement of products for ease of use, reversibility, and high safety is the priority for the field.

Understanding and interpreting community sequencing measurements of the vaginal microbiome

Community-wide high-throughput sequencing has transformed the study of the vaginal microbiome, and clinical applications are on the horizon. Here we outline the three main community sequencing methods: (1) amplicon sequencing, (2) shotgun metagenomic sequencing, and (3) metatranscriptomic sequencing. We discuss the advantages and limitations of community sequencing generally, and the unique strengths and weaknesses of each method. We briefly review the contributions of community sequencing to vaginal microbiome research and practice. We develop suggestions for critically interpreting research results and potential clinical applications based on community sequencing of the vaginal microbiome. TWEETABLE ABSTRACT: We review the advantages and limitations of amplicon sequencing, metagenomics, and metatranscriptomics methods for the study of the vaginal microbiome.