Pharmacology of Antiretrovirals in the Female Genital Tract for HIV Prevention

Lenacapavir: Playing the Long Game in the New Era of Antiretrovirals

The mainstay of antiretroviral therapy (ART) has been combination oral therapy. While oral ART is highly effective, nonadherence remains a chief concern. Addressing this concern in recent years is the emergence of long-acting antiretrovirals for the treatment and prevention of HIV-1 infection. The most recently approved long-acting antiretroviral is the first-in-class capsid inhibitor lenacapavir (LEN) for heavily treatment-experienced adults with multidrug-resistant HIV-1 infection. Due to its biannual subcutaneous dosing scheme to inhibit the HIV-1 capsid, LEN exhibits unique pharmacokinetics and reinforces an evolving era of ART. In this review, we evaluate published and accepted research articles, conference proceedings, and clinical trial records to provide a comprehensive overview of LEN for treatment and preliminary data for the prevention of HIV-1 infection. These data include clinical trials outcomes, in vitro and in vivo resistance profiles, and preclinical data supporting downstream indications. We also discuss the unique clinical pharmacology of LEN with the goal of serving as a resource toward subsequent physiologically based, population-based, and other miscellaneous pharmacometric-focused analyses. Given the dynamic nature of the HIV treatment and prevention research fields, we also discuss ongoing studies related to LEN for treatment-naïve adults and for prevention. Lastly, we discuss important pharmacologic gaps in special populations, drug-drug interactions, and at the sites of action germane to HIV treatment and prevention. The information discussed in this review will provide knowledge and understanding of the unique pharmacologic properties of LEN to assist clinicians and researchers as they navigate the dynamic HIV research landscape.

Single-nucleotide polymorphisms in ABC drug transporters alter expression and circulating tenofovir in healthy South African women exposed to pre-exposure prophylaxis

Aim: We investigated if single-nucleotide polymorphisms (SNPs) in ATP-binding cassette (ABC) drug transporters alter gene expression and tenofovir disposition in South African women taking Truvada® for HIV prevention. Materials & methods: In 393 women, real-time PCR was used to determine the associations between six SNPs in ABC transporter genes, mRNA expression and circulating-tenofovir. Results: Univariable and multivariable analyses showed that CT and TT relative to CC genotypes for the ABCC4(3463C/T) SNP had significantly higher tenofovir levels. In contrast, the AA genotype for the ABCC4(4976A/G) SNP showed significantly less tenofovir, while mRNA expression was increased. Conclusion: SNPs in the ABCC4 gene may differentially affect gene expression and circulating tenofovir. Their impact may inform on low pre-exposure prophylaxis efficacy and discern effective drugs in clinical trials of African women enriched for certain genotypes.

Pharmacogenomics of drug transporters for antiretroviral long-acting pre-exposure prophylaxis for HIV

The use of antiretrovirals (ARVs) as oral, topical, or long-acting pre-exposure prophylaxis (PrEP) has emerged as a promising strategy for HIV prevention. Clinical trials testing Truvada® [tenofovir disoproxil fumarate (TDF)/tenofovir (TFV) and emtricitabine (FTC)] as oral or topical PrEP in African women showed mixed results in preventing HIV infections. Since oral and topical PrEP effectiveness is dependent on adequate drug delivery and availability to sites of HIV infection such as the blood and female genital tract (FGT); host biological factors such as drug transporters have been implicated as key regulators of PrEP. Drug transporter expression levels and function have been identified as critical determinants of PrEP efficacy by regulating PrEP pharmacokinetics across various cells and tissues of the blood, renal tissues, FGT mucosal tissues and other immune cells targeted by HIV. In addition, biological factors such as genetic polymorphisms and genital inflammation also influence drug transporter expression levels and functionality. In this review, drug transporters and biological factors modulating drug transporter disposition are used to explain discrepancies observed in PrEP clinical trials. This review also provides insight at a pharmacological level of how these factors further increase the susceptibility of the FGT to HIV infections, subsequently contributing to ineffective PrEP interventions in African women.

Genital Immune Cell Activation and Tenofovir Gel Efficacy: A Case-Control Study

Genital inflammation (GI) undermines topical human immunodeficiency virus (HIV) pre-exposure prophylaxis (PrEP) efficacy through unknown mechanisms. Here, associations between activated endocervical CD4 + T-cell numbers and higher deoxyadenosine triphosphate (dATP) concentrations suggest that competition for intracellular metabolites within HIV target cells may reduce the efficacy of antiretroviral-based PrEP in women with GI.

Validation and clinical application of a method to quantify efavirenz in cervicovaginal secretions from flocked swabs using liquid chromatography tandem mass spectrometry

Background : A liquid chromatography tandem mass spectrometry method to quantify drugs in dried cervicovaginal secretions from flocked swabs was developed and validated using the antiretroviral efavirenz as an example. Methods: Cervicovaginal swabs (CVS) were prepared by submerging flocked swabs in efavirenz-spiked plasma matrix. Time to full saturation, weight uniformity, recovery and room temperature stability were evaluated. Chromatographic separation was on a reverse-phase C18 column by gradient elution using 1mM ammonium acetate in water/acetonitrile at 400 µL/min. Detection and quantification were on a TSQ Quantum Access triple quadrupole mass spectrometer operated in negative ionisation mode. The method was used to quantify efavirenz in CVS samples from human immunodeficiency virus (HIV)-positive women in the VADICT study (NCT03284645). A total of 98 samples (35 paired intensive CVS and DBS pharmacokinetic samples, 14 paired sparse CVS and DBS samples) from 19 participants were available for this analysis. Results: Swabs were fully saturated within 15 seconds, absorbing 128 µL of plasma matrix with coefficient of variation (%CV) below 1.3%. The method was linear with a weighting factor (1/X) in the range of 25-10000 ng/mL with inter- and intra-day precision (% CV) of 7.69-14.9%, and accuracy (% bias) of 99.1-105.3%. Mean recovery of efavirenz from CVS was 83.8% (%CV, 11.2) with no significant matrix effect. Efavirenz remained stable in swabs for at least 35 days after drying and storage at room temperature. Median (range) CVS efavirenz AUC 0-24h was 16370 ng*h/mL (5803-22088), C max was 1618 ng/mL (610-2438) at a T max of 8.0 h (8.0-12), and C min was 399 ng/mL (110-981). Efavirenz CVS:plasma AUC 0-24h ratio was 0.41 (0.20-0.59). Conclusions: Further application of this method will improve our understanding of the pharmacology of other therapeutics in the female genital tract, including in low- and middle-income countries.

Impact of Dapivirine and Placebo Vaginal Rings on the Microbiota of Adolescent, Lactating, and Postmenopausal Females

BACKGROUND

A 25-mg dapivirine vaginal ring has been demonstrated to reduce risk of human immunodeficiency virus (HIV) acquisition in nonpregnant adult women. In this secondary analysis of studies conducted in US adolescent, lactating, and postmenopausal females, vaginal microbiota was assessed prior to and after ring use, and between dapivirine and placebo ring users.

METHODS

Vaginal fluid swabs were collected before and after product use for the evaluation of microbiota using Nugent criteria, quantitative culture, and quantitative polymerase chain reaction.

RESULTS

Vaginal ring use did not impact bacterial vaginosis prevalence among the 3 populations and was associated with minimal shifts in microbiota. Adolescents in both arms demonstrated an increased prevalence of Lactobacillus crispatus and a decrease in quantity of Megasphaera lornae. Postmenopausal active and placebo ring users demonstrated an increased prevalence of lactobacilli and non-albicans yeast, while dapivirine ring users demonstrated an increased prevalence of Candida albicans and increased quantity of group B Streptococcus and non-albicans yeasts. Prevotella species were increased in lactating women, whereas Prevotella timonensis increased in prevalence and concentration among adolescent and postmenopausal females and Prevotella bivia increased in prevalence among adolescent dapivirine ring users.

CONCLUSIONS

Dapivirine vaginal ring use was associated with minimal changes in the vaginal microbiota that are likely not clinically significant.

Validation and clinical application of a method to quantify efavirenz in cervicovaginal secretions from flocked swabs using liquid chromatography tandem mass spectrometry

Background : A liquid chromatography tandem mass spectrometry method to quantify drugs in dried cervicovaginal secretions from flocked swabs was developed and validated using the antiretroviral efavirenz as an example. Methods: Cervicovaginal swabs (CVS) were prepared by submerging flocked swabs in efavirenz-spiked plasma matrix. Time to full saturation, weight uniformity, recovery and room temperature stability were evaluated. Chromatographic separation was on a reverse-phase C18 column by gradient elution using 1mM ammonium acetate in water/acetonitrile at 400 µL/min. Detection and quantification were on a TSQ Quantum Access triple quadrupole mass spectrometer operated in negative ionisation mode. The method was used to quantify efavirenz in CVS samples from human immunodeficiency virus (HIV)-positive women in the VADICT study (NCT03284645). A total of 98 samples (35 paired intensive CVS and DBS pharmacokinetic samples, 14 paired sparse CVS and DBS samples) from 19 participants were available for this analysis. Results: Swabs were fully saturated within 15 seconds, absorbing 128 µL of plasma matrix with coefficient of variation (%CV) below 1.3%. The method was linear with a weighting factor (1/X) in the range of 25-10000 ng/mL with inter- and intra-day precision (% CV) of 7.69-14.9%, and accuracy (% bias) of 99.1-105.3%. Mean recovery of efavirenz from CVS was 83.8% (%CV, 11.2) with no significant matrix effect. Efavirenz remained stable in swabs for at least 35 days after drying and storage at room temperature. Median (range) CVS efavirenz AUC 0-24h was 16370 ng*h/mL (5803-22088), C max was 1618 ng/mL (610-2438) at a T max of 8.0 h (8.0-12), and C min was 399 ng/mL (110-981). Efavirenz CVS:plasma AUC 0-24h ratio was 0.41 (0.20-0.59). Conclusions: Further application of this method will improve our understanding of the pharmacology of other therapeutics in the female genital tract, including in low- and middle-income countries.

Validation and clinical application of a method to quantify efavirenz in cervicovaginal secretions from flocked swabs using liquid chromatography tandem mass spectrometry

Background: A liquid chromatography tandem mass spectrometry method to quantify drugs in dried cervicovaginal secretions from flocked swabs was developed and validated using the antiretroviral efavirenz as an example. Methods: Cervicovaginal swabs (CVS) were prepared by submerging flocked swabs in efavirenz-spiked matrix. Time to full saturation, weight uniformity, recovery and room temperature stability were evaluated. Chromatographic separation was on a reverse-phase C18 column by gradient elution using 1mM ammonium acetate in water/acetonitrile at 400 µL/min. Detection and quantification were on a TSQ Quantum Access triple quadrupole mass spectrometer operated in negative ionisation mode. The method was used to quantify efavirenz in CVS samples from human immunodeficiency virus (HIV)-positive women in the VADICT study (NCT03284645). A total of 98 samples (35 paired intensive CVS and DBS samples, 14 paired sparse CVS and DBS samples) from 19 participants were available for this analysis. Results: Swabs were fully saturated within 15 seconds, absorbing 128 µL of matrix with coefficient of variation (%CV) below 1.3%. The method was linear with a weighting factor (1/X) in the range of 25-10000 ng/mL with inter- and intra-day precision (% CV) of 7.69-14.9%, and accuracy (% bias) of 99.1-105.3%. Mean recovery of efavirenz from CVS was 83.8% (%CV, 11.2) with no significant matrix effect. Efavirenz remained stable in swabs for at least 35 days after drying and storage at room temperature. Median (range) CVS efavirenz AUC 0-24h was 16370 ng*h/mL (5803-22088), C max was 1618 ng/mL (610-2438) at a T max of 8.0 h (8.0-12), and C min was 399 ng/mL (110-981). Efavirenz CVS:plasma AUC 0-24 ratio was 0.41 (0.20-0.59). Conclusions: Further application of this method will improve our understanding of the pharmacology of other therapeutics in the female genital tract, including in low- and middle-income countries.

Early Colorectal Responses to HIV-1 and Modulation by Antiretroviral Drugs

Innate responses during acute HIV infection correlate with disease progression and pathogenesis. However, limited information is available about the events occurring during the first hours of infection in the mucosal sites of transmission. With an ex vivo HIV-1 challenge model of human colorectal tissue we assessed the mucosal responses induced by R5- and X4-tropic HIV-1 isolates in the first 24 h of exposure. Microscopy studies demonstrated virus penetration of up to 39 μm into the lamina propia within 6 h of inoculation. A rapid, 6 h post-challenge, increase in the level of secretion of inflammatory cytokines, chemokines, interferon- γ (IFN-γ), and granulocyte-macrophage colony-stimulating factor (GM-CSF) was observed following exposure to R5- or X4-tropic isolates. This profile persisted at the later time point measured of 24 h. However, exposure to the X4-tropic isolate tested induced greater changes at the proteomic and transcriptomic levels than the R5-tropic. The X4-isolate induced greater levels of CCR5 ligands (RANTES, MIP-1α and MIP-1β) secretion than R5-HIV-1. Potential drugs candidates for colorectal microbicides, including entry, fusion or reverse transcriptase inhibitors demonstrated differential capacity to modulate these responses. Our findings indicate that in colorectal tissue, inflammatory responses and a Th1 cytokine profile are induced in the first 24 h following viral exposure.

Pharmacology of HIV Cure: Site of Action

Despite significant advances in HIV treatment over the past 30 years, critical barriers to an HIV cure persist. The HIV reservoir, defined at both the cellular and anatomical level, constitutes the main barrier to cure. While the mechanisms underlying the reservoir are not yet well understood, one theory to explain persistence at the anatomical level is that subtherapeutic exposure to antiretroviral therapy (ART) within certain tissue compartments permits ongoing replication. Characterizing ART pharmacology throughout the body is important in the context of these potential pharmacologic sanctuaries and for maximizing the probability of success with forthcoming cure strategies that rely on latency reversal and require ART to prevent reseeding the reservoir. In this review, we provide a comprehensive overview of ART and latency reversal agent distribution at the site of action for HIV cure (i.e., anatomical sites commonly associated with HIV persistence, such as lymphoid organs and the central nervous system). We also discuss methodologic approaches that provide insight into HIV cure pharmacology, including experimental design and advances within the computational, pharmaceutical, and analytical chemistry fields. The information discussed in this review will assist in streamlining the development of investigational cure strategies by providing a roadmap to ensure therapeutic exposure within the site of action for HIV cure.

Influence of Plasticizers on the pH-Dependent Drug Release and Cellular Interactions of Hydroxypropyl Methylcellulose/Zein Vaginal Anti-HIV Films Containing Tenofovir

Vaginal films featuring the pH-dependent release of tenofovir (TFV) were developed for the prevention of sexual transmission of human immunodeficiency syndrome (HIV). Films based on hydroxypropyl methylcellulose and zein were prepared incorporating different plasticizers [oleic acid, lactic acid, glycerol, and polyethylene glycol 400 (PEG)] and evaluated for in vitro drug release in an acidic simulated vaginal fluid (pH 4.2) and a slightly alkaline mixture of simulated seminal and vaginal fluids (pH 7.5). Results revealed that optimal biphasic TFV release was possible with proper combination of plasticizers (PEG and oleic acid, 1:7 w/w) and by adjusting the plasticizer/matrix-forming material ratio. The films had similar or higher levels of TFV associated with genital epithelial cells (Ca Ski or HEC-1-A cells) but lower drug permeability compared to the free drug. These data confirm that films have the potential to achieve suitable mucosal levels of TFV with low systemic exposure. The films developed could protect women from HIV sexual transmission.

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.

Smart Freeze-Dried Bigels for the Prevention of the Sexual Transmission of HIV by Accelerating the Vaginal Release of Tenofovir during Intercourse

Sub-Saharan African women are still at risk from the human immunodeficiency virus (HIV), and sex with men is the main route of transmission. Vaginal formulations containing antiretroviral drugs are promising tools to give women the power to protect themselves. The aim of this work was to obtain freeze-dried bigels containing pectin, chitosan, or hypromellose for the vaginal controlled release of Tenofovir, which is accelerated in the presence of semen. Nine batches of bigels were formulated using different proportions of these polymers in the hydrogel (1, 2, and 3% w/w). The bigels obtained were freeze-dried and then underwent hardness and deformability, mucoadhesion, swelling, and drug release tests, the last two in simulated vaginal fluid (SVF) and SVF/simulated seminal fluid (SSF) mixture. The formulation containing 3% pectin (fd3P) has the highest values for hardness, resistance to deformation, and good mucoadhesivity. Its swelling is conditioned by the pH of the medium, which is responsive to the controlled release of Tenofovir in SVF, with the fastest release in the SVF/SSF mixture. fd3P would be an interesting smart microbicidal system to allow faster release of Tenofovir in the presence of semen, and thus increase women’s ability to protect themselves from the sexual transmission of HIV.