Novel preclinical models of topical PrEP pharmacodynamics provide rationale for combination of drugs with complementary properties

Tenofovir disoproxil fumarate intravaginal ring for HIV pre-exposure prophylaxis in sexually active women: a phase 1, single-blind, randomised, controlled trial

BACKGROUND

An intravaginal ring that releases the tenofovir prodrug, tenofovir disoproxil fumarate, provided 100% protection in macaques against simian HIV and was safe in a 14-day clinical trial in sexually abstinent women. We aimed to assess the safety and pharmacokinetics of this intravaginal ring over 90 days in sexually active women.

METHODS

We did a phase 1, single-blind, randomised, placebo-controlled trial to assess safety, pharmacokinetics, and acceptability of a tenofovir disoproxil fumarate intravaginal ring used continuously with monthly ring changes for 3 months. Sexually active women who were HIV negative were randomly assigned (3:1) to a tenofovir disoproxil fumarate ring or placebo ring. Primary safety endpoint was the proportion of women who had grade 2 or higher genitourinary adverse events judged related to study product and any grade 2 or higher adverse event as defined by the Division of AIDS Table for Grading the Severity of Adult and Pediatric Adverse Events. We quantified tenofovir disoproxil fumarate and tenofovir concentrations in cervicovaginal fluid, tenofovir in plasma, and tenofovir diphosphate, the active metabolite, in cervical tissue and dried blood spots 1 month after each ring insertion. We compared changes over time in cervicovaginal fluid cytokine and chemokine concentrations and vaginal microbiota. The study was electively stopped early and is registered with ClinicalTrials.gov, number NCT02762617.

FINDINGS

Between Feb 24 and July 20, 2017, 17 women were enrolled before study termination. 12 were assigned to receive the tenofovir disoproxil fumarate ring and five were assigned to receive the placebo ring. Two participants in the tenofovir disoproxil fumarate ring group completed 3 months of continuous ring use; eight were asked to discontinue ring use early because of ulcerations (grade 1) near the ring; in the remaining two women, rings were electively removed by study staff on day 20 and day 23. Ulcers were detected a mean of 32 days after ring use (range 23-56). Four of eight participants with ulcers were symptomatic with vaginal discharge; four had ulcers identified when examined; three had two ulcers; all ulcers resolved after ring removal. No participants in the placebo group developed ulcers. No grade 2 product-related adverse events were reported in either group and four non-product-related grade 2 adverse events were reported in the tenofovir disoproxil fumarate ring group. Cervicovaginal fluid tenofovir concentrations did not differ at day 14 (p=0·14) comparing the eight patients who did (median 1·0 × 105 ng/mL [IQR 9·1 × 104-1·1 × 105]) with the four who did not (6·0 × 104 ng/mL [5·6 × 104-1·1 × 105]) develop ulcers. No significant changes in vaginal microbiota were detected in either group. Concentrations of multiple inflammatory cytokines and chemokines were significantly higher at days 14 and 28 compared with baseline in the tenofovir disoproxil fumarate ring group but not the placebo group.

INTERPRETATION

Future studies are needed to establish whether the unanticipated finding of ulcerations is specific to this tenofovir disoproxil fumarate ring or generalisable to other sustained topical release formulations of tenofovir or its prodrugs.

FUNDING

National Institutes of Health.

Effects of gel volume on pharmacokinetics for vaginal and rectal applications of combination DuoGel-IQB4012, a dual chamber-dual drug HIV microbicide gel, in pigtailed macaques

This study evaluated effects of differing gel volumes on pharmacokinetics (PK). IQB4012, a gel containing the non-nucleoside reverse transcriptase inhibitor IQP-0528 and tenofovir (TFV), was applied to the pigtailed macaque vagina and rectum. Vaginal gel volumes (1% loading of both drugs) were 0.5 or 1.5 ml; following wash-out, 1 or 4 ml of gel were then applied rectally. Blood, vaginal, and rectal fluids were collected at 0, 2, 4, and 24 h. Vaginal and rectal tissue biopsies were collected at 4 and 24 h. There were no statistically significant differences in concentrations for either drug between gel volumes within compartments at matched time points. After vaginal gel application, median IQP-0528 concentrations were ~ 10⁴-10⁵ ng/g, 10⁵-10⁶ ng/ml, and 10³-10⁵ ng/ml in vaginal tissues, vaginal fluids, and rectal fluids, respectively (over 24 h). Median vaginal TFV concentrations were 1-2 logs lower than IQP-0528 levels at matched time points. After rectal gel application, median IQP-0528 and TFV concentrations in rectal fluids were ~ 10³-10⁵ ng/ml and ~ 10²-10³ ng/ml, respectively. Concentrations of both drugs sampled in rectal tissues were low (~ 10¹-10³ ng/g). For 1 ml gel, half of sampled rectal tissues had undetectable concentrations of either drug, and over half of sampled rectal fluids had undetectable TFV concentrations. These results indicate differences in drug delivery between the vaginal and rectal compartments, and that smaller vaginal gel volumes may not significantly compromise microbicide PK and prophylactic potential. However, effects of rectal gel volume on PK for both drugs were less definitive.

Improving the clinical relevance of a mouse pregnancy model of antiretroviral toxicity; a pharmacokinetic dosing-optimization study of current HIV antiretroviral regimens

Animal models can be useful tools for the study of HIV antiretroviral (ARV) safety/toxicity in pregnancy and the mechanisms that underlie ARV-associated adverse events. The utility and translatability of animal model-based ARV safety/toxicity data is improved if ARVs are tested in clinically relevant concentrations. The objective of this work was to improve the clinical relevance of our mouse pregnancy model of ARV toxicity, by determining the doses of currently prescribed ARV regimens that would yield human therapeutic plasma concentrations. Pregnant mice were administered increasing doses of ARV combinations by oral gavage, followed by measurement of drug concentrations in the maternal plasma and amniotic fluid. Concentrations of ten different ARVs in maternal plasma and amniotic fluid samples of pregnant mice are presented, with dosing optimization to yield human pregnancy-relevant plasma drug concentrations. We have proposed optimal dosing for different regimen component drugs to achieve human therapeutic plasma levels, so that a clinically relevant standard dosing is established. A review of related ARV pharmacokinetic studies in (pregnant/non-pregnant) rodents and human pregnancy is also shown. We hope these data will inform and encourage the use of mouse pregnancy models in the study of ARV safety/toxicity.

Vaginal microbiome modulates topical antiretroviral drug pharmacokinetics

Tenofovir gel and dapivirine ring provided variable HIV protection in clinical trials, reflecting poor adherence and possibly biological factors. We hypothesized that vaginal microbiota modulates pharmacokinetics and tested the effects of pH, individual bacteria, and vaginal swabs from women on pharmacokinetics and antiviral activity. Tenofovir, but not dapivirine, uptake by human cells was reduced as pH increased. Lactobacillus crispatus actively transported tenofovir leading to a loss in drug bioavailability and culture supernatants from Gardnerella vaginalis, but not Atopobium vaginae, blocked tenofovir endocytosis. The inhibition of endocytosis mapped to adenine. Adenine increased from 65.5 μM in broth to 246 μM in Gardnerella, but decreased to 9.5 μM in Atopobium supernatants. This translated into a decrease in anti-HIV activity when Gardnerella supernatants or adenine were added to cultures. Dapivirine was also impacted by microbiota, as drug bound irreversibly to bacteria, resulting in decreased antiviral activity. When drugs were incubated with vaginal swabs, 30.7% ± 5.7% of dapivirine and 63.9% ± 8.8% of tenofovir were recovered in supernatants after centrifugation of the bacterial cell pellet. In contrast, no impact of microbiota on the pharmacokinetics of the prodrugs, tenofovir disoproxil fumarate or tenofovir alafenamide, was observed. Together, these results demonstrate that microbiota may impact pharmacokinetics and contribute to inconsistent efficacy.

Prevention of vaginal and rectal HIV transmission by antiretroviral combinations in humanized mice

With more than 7,000 new HIV infections daily worldwide, there is an urgent need for non-vaccine biomedical prevention (nBP) strategies that are safe, effective, and acceptable. Clinical trials have demonstrated that pre-exposure prophylaxis (PrEP) with antiretrovirals (ARVs) can be effective at preventing HIV infection. In contrast, other trials using the same ARVs failed to show consistent efficacy. Topical (vaginal and rectal) dosing is a promising regimen for HIV PrEP as it leads to low systematic drug exposure. A series of titration studies were carried out in bone marrow/liver/thymus (BLT) mice aimed at determining the adequate drug concentrations applied vaginally or rectally that offer protection against rectal or vaginal HIV challenge. The dose-response relationship of these agents was measured and showed that topical tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) can offer 100% protection against rectal or vaginal HIV challenges. From the challenge data, EC50 values of 4.6 μM for TDF and 0.6 μM for FTC for HIV vaginal administration and 6.1 μM TDF and 0.18 μM for FTC for rectal administration were obtained. These findings suggest that the BLT mouse model is highly suitable for studying the dose-response relationship in single and combination ARV studies of vaginal or rectal HIV exposure. Application of this sensitive HIV infection model to more complex binary and ternary ARV combinations, particularly where agents have different mechanisms of action, should allow selection of optimal ARV combinations to be advanced into pre-clinical and clinical development as nBP products.

Nanoparticle Encapsulation for Antiretroviral Pre-Exposure Prophylaxis

HIV continues to be one of the greatest challenges facing the global health community. More than 36 million people currently live with HIV and, in 2015 2.1 million new infections were reported globally. Pre-Exposure Prophylaxis (PrEP) prevents HIV infection by inhibiting viral entry, replication, or integration at the primary site of pathogenic contraction. Failures of large antiretroviral drug (ARV) PrEP clinical trials indicate the current insufficiencies of PrEP for women in high-risk areas, such as sub-Saharan Africa. A combination of social, adherence, and drug barriers create these insufficiencies and limit the efficacy of ARV. Nanotechnology offers the promise of extended drug release and enhances bioavailability of ARVs when encapsulated in polymeric nano-particles. Nanoparticle encapsulation has been evaluated in vitro in comparative studies to drug solutions and exhibit higher efficacy and lower cytotoxicity profiles. Delivery systems for nanoparticle PrEP facilitate administration of nano-encapsulated ARVs to high-risk tissues. In this mini-review, we summarize the comparative nanoparticle and drug solution studies and the potential of two delivery methods: thermosensitive gels and polymeric nanoparticle films for direct prophylactic applications.

A Dose Ranging Pharmacokinetic Evaluation of IQP-0528 Released from Intravaginal Rings in Non-Human Primates

PURPOSE

Design of intravaginal rings (IVRs) for delivery of antiretrovirals is often guided by in vitro release under sink conditions, based on the assumption that in vivo release will follow a similar release profile.

METHODS

We conducted a dose-ranging study in the female reproductive tract of pigtail macaques using matrix IVRs containing IQP-0528, a poorly soluble but highly potent antiretroviral drug with an IC₉₀ of 146 ng/mL. These IVRs consisted of drug-loaded segments, 15.6% IQP-0528 in Tecoflex 85A, comprising either all, half, or a quarter of the entire ring.

RESULTS

In vitro release under sink conditions demonstrates loading-proportional release, with a cumulative 30-day release of 48.5 ± 2.2 mg for our 100% loaded ring, 24.8 ± .36 mg from our 50% loaded ring, and 13.99 ± 1.58 mg from our 25% loaded ring. In vivo, while drug concentration in vaginal fluid is well in excess of IQP-0528's EC₉₀, we find no statistical difference between the different ring loadings in either swab drug levels or drug released from our rings.

CONCLUSIONS

We show that in vitro release may not accurately reflect in vivo release, particularly for poorly soluble drugs. All tested loadings of our IVRs are capable of delivering IQP-0528 well in excess of the IC₉₀.

Evaluation of poly(lactic-co-glycolic acid) and poly(dl-lactide-co-ε-caprolactone) electrospun fibers for the treatment of HSV-2 infection

More diverse multipurpose prevention technologies are urgently needed to provide localized, topical pre-exposure prophylaxis against sexually transmitted infections (STIs). In this work, we established the foundation for a multipurpose platform, in the form of polymeric electrospun fibers (EFs), to physicochemically treat herpes simplex virus 2 (HSV-2) infection. To initiate this study, we fabricated different formulations of poly(lactic-co-glycolic acid) (PLGA) and poly(dl-lactide-co-ε-caprolactone) (PLCL) EFs that encapsulate Acyclovir (ACV), to treat HSV-2 infection in vitro. Our goals were to assess the release and efficacy differences provided by these two different biodegradable polymers, and to determine how differing concentrations of ACV affected fiber efficacy against HSV-2 infection and the safety of each platform in vitro. Each formulation of PLGA and PLCL EFs exhibited high encapsulation efficiency of ACV, sustained-delivery of ACV through one month, and in vitro biocompatibility at the highest doses of EFs tested. Additionally, all EF formulations provided complete and efficacious protection against HSV-2 infection in vitro, regardless of the timeframe of collected fiber eluates tested. This work demonstrates the potential for PLGA and PLCL EFs as delivery platforms against HSV-2, and indicates that these delivery vehicles may be expanded upon to provide protection against other sexually transmitted infections.

Will dapivirine redeem the promises of anti-HIV microbicides? Overview of product design and clinical testing

Microbicides are being developed in order to prevent sexual transmission of HIV. Dapivirine, a non-nucleoside reverse transcriptase inhibitor, is one of the leading drug candidates in the field, currently being tested in various dosage forms, namely vaginal rings, gels, and films. In particular, a ring allowing sustained drug release for 1month is in an advanced stage of clinical testing. Two parallel phase III clinical trials are underway in sub-Saharan Africa and results are expected to be released in early 2016. This article overviews the development of dapivirine and its multiple products as potential microbicides, with particular emphasis being placed on clinical evaluation. Also, critical aspects regarding regulatory approval, manufacturing, distribution, and access are discussed.

Safety and Pharmacokinetics of Quick-Dissolving Polymeric Vaginal Films Delivering the Antiretroviral IQP-0528 for Preexposure Prophylaxis

For human immunodeficiency virus (HIV) prevention, microbicides or drugs delivered as quick-dissolving films may be more acceptable to women than gels because of their compact size, minimal waste, lack of an applicator, and easier storage and transport. This has the potential to improve adherence to promising products for preexposure prophylaxis. Vaginal films containing IQP-0528, a nonnucleoside reverse transcriptase inhibitor, were evaluated for their pharmacokinetics in pigtailed macaques. Polymeric films (22 by 44 by 0.1 mm; providing 75% of a human dose) containing IQP-0528 (1.5%, wt/wt) with and without poly(lactic-co-glycolic acid) (PLGA) nanoparticle encapsulation were inserted vaginally into pigtailed macaques in a crossover study design (n = 6). With unencapsulated drug, the median (range) vaginal fluid concentrations of IQP-0528 were 160.97 (2.73 to 2,104), 181.79 (1.86 to 15,800), and 484.50 (8.26 to 4,045) μg/ml at 1, 4, and 24 h after film application, respectively. Median vaginal tissue IQP-0528 concentrations at 24 h were 3.10 (0.03 to 222.58) μg/g. The values were similar at locations proximal, medial, and distal to the cervix. The IQP-0528 nanoparticle-formulated films delivered IQP-0528 in vaginal tissue and secretions at levels similar to those obtained with the unencapsulated formulation. A single application of either formulation did not disturb the vaginal microflora or the pH (7.24 ± 0.84 [mean ± standard deviation]). The high mucosal IQP-0528 levels delivered by both vaginal film formulations were between 1 and 5 log higher than the in vitro 90% inhibitory concentration (IC90) of 0.146 μg/ml. The excellent coverage and high mucosal levels of IQP-0528, well above the IC90, suggest that the films may be protective and warrant further evaluation in a vaginal repeated low dose simian-human immunodeficiency virus (SHIV) transmission study in macaques and clinically in women.

A phase 1 randomized placebo-controlled safety and pharmacokinetic trial of a tenofovir disoproxil fumarate vaginal ring

BACKGROUND

Tenofovir disoproxil fumarate (TDF), a prodrug of tenofovir (TFV), may be ideal for topical HIV preexposure prophylaxis because it has higher tissue and cell permeability than TFV; is not adversely impacted by seminal proteins; and its active metabolite, TFV-diphosphate (TFV-DP), has a long intracellular half-life. We engineered a TDF eluting polyurethane reservoir intravaginal ring (IVR) to provide near constant mucosal antiretroviral concentrations.

METHODS

A first-in-human randomized placebo-controlled trial was conducted to assess the safety and pharmacokinetics of the TDF IVR in healthy, sexually abstinent women (15 TDF and 15 placebo). Drug concentrations were measured in cervicovaginal fluid (CVF) obtained by swab, cervical tissue, plasma, and dried blood spots (DBS) over 14 days of continuous ring use.

RESULTS

There were 43 total, 23 reproductive tract, and eight product-related grade 1 adverse events. Steady-state CVF TFV concentrations were achieved proximal (vagina, ectocervix) and distal (introitus) to the TDF IVR 1 day after ring insertion. Median tissue TFV-DP concentrations 14 days after TDF IVR placement were 120 fmol/mg (interquartile range 90, 550). CVF collected from the cervix 1 week and 2 weeks after TDF IVR insertion provided significant protection against ex-vivo HIV challenge. Eleven of 14 (78%) participants had detectable TFV-DP DBS concentrations 14 days after TDF IVR placement, suggesting that DBS may provide a surrogate marker of adherence in future clinical trials.

CONCLUSION

A TDF IVR is safe, well tolerated, and results in mucosal TFV concentrations that exceed those associated with HIV protection. The findings support further clinical evaluation of this TDF IVR.

Controlling the hydration rate of a hydrophilic matrix in the core of an intravaginal ring determines antiretroviral release

Intravaginal ring technology is generally limited to releasing low molecular weight species that can diffuse through the ring elastomer. To increase the diversity of drugs that can be delivered from intravaginal rings, we designed an IVR that contains a drug matrix encapsulated in the core of the IVR whereby the mechanism of drug release is uncoupled from the interaction of the drug with the ring elastomer. We call the device a flux controlled pump, and it is comprised of compressed pellets of a mixture of drug and hydroxypropyl cellulose within the hollow core of the ring. The pump orifice size and chemistry of the polymer pellets control the rate of hydration and diffusion of the drug-containing hydroxypropyl cellulose gel from the device. A mechanistic model describing the hydration and diffusion of the hydroxypropyl cellulose matrix is presented. Good agreement between the quantitative model predictions and the experimental studies of drug release was obtained. We achieved controlled release rates of multiple antiretrovirals ranging from μg/d to mg/d by altering the orifice design, drug loading, and mass of pellets loaded in the device. This device could provide an adaptable platform for the vaginal drug delivery of many molecules.

Pharmacokinetic and Pharmacodynamic Evaluation following Vaginal Application of IQB3002, a Dual-Chamber Microbicide Gel Containing the Nonnucleoside Reverse Transcriptase Inhibitor IQP-0528 in Rhesus Macaques

We evaluated the in vivo pharmacokinetics and used a complementary ex vivo coculture assay to determine the pharmacodynamics of IQB3002 gel containing 1% IQP-0528, a nonnucleoside reverse transcriptase inhibitor (NNRTI), in rhesus macaques (RM). The gel (1.5 ml) was applied vaginally to 6 simian-human immunodeficiency (SHIV)-positive female RM. Blood, vaginal fluids, and rectal fluids were collected at 0, 1, 2, and 4 h. RM were euthanized at 4 h, and vaginal, cervical, rectal, and regional lymph node tissues were harvested. Anti-human immunodeficiency virus (HIV) activity was evaluated ex vivo by coculturing fresh or frozen vaginal tissues with activated human peripheral blood mononuclear cells (PBMCs) and measuring the p24 levels for 10 days after an HIV-1Ba-L challenge. The median levels of IQP-0528, determined using liquid chromatography-tandem mass spectroscopy (LC-MS/MS) methods, were between 10(4) and 10(5) ng/g in vaginal and cervical tissue, between 10(3) and 10(4) ng/g in rectal tissues, and between 10(5) and 10(7) ng/ml in vaginal fluids over the 4-h period. The vaginal tissues protected the cocultured PBMCs from HIV-1 infection ex vivo, with a viral inhibition range of 81 to 100% in fresh and frozen tissues that were proximal, medial, and distal relative to the cervix. No viral inhibition was detected in untreated baseline tissues. Collectively, the median drug levels observed were 5 to 7 logs higher than the in vitro 50% effective concentration (EC50) range (0.21 ng/ml to 1.29 ng/ml), suggesting that 1.5 ml of the gel delivers IQP-0528 throughout the RM vaginal compartment at levels that are highly inhibitory to HIV-1. Importantly, antiviral activity was observed in both fresh and frozen vaginal tissues, broadening the scope of the ex vivo coculture model for future NNRTI efficacy studies.

Impact of Sex on the Pharmacokinetics and Pharmacodynamics of 1% Tenofovir Gel

BACKGROUND

Tenofovir (TFV) gel partially protected against human immunodeficiency virus (HIV) in one but not subsequent trials. The disappointing results were attributed largely to poor adherence. However, timing of gel application relative to sex may impact pharmacokinetics and contribute to outcomes. Thus, we conducted a single-dose pharmacokinetic study of TFV gel applied 1 or 24 hours before or 1 hour before and 1 hour after (BAT) sex and compared results with dosing without sex.

METHODS

Twenty-four couples were enrolled; cervicovaginal lavage (CVL) and tissue were collected 2 hours after sex with matching timed collections at no sex visits and assayed for drug concentrations and CVL anti-HIV activity.

RESULTS

Compared with dosing without sex, median TFV concentrations after sex decreased 72% and 78% (P < .001) in CVL, 75% and 71% (P < .001) in vaginal tissue, and 75% (P = .06) and 55% (P < .001) in cervical tissue with -1 hour and -24 hour dosing, respectively. Median concentration of TFV-diphosphate also decreased significantly in cervical tissue with -1 hour, dosing. BAT dosing resulted in drug levels at least as great as those in the absence of sex. Percent inhibition of HIV infection by post-coital CVL increased significantly from median (interquartile range) of 55% (54%) in the absence of gel to 99% (7%), 77% (57%), and 100% (0.4%) with -1 hour, -24 hour, or BAT dosing, respectively, and correlated significantly with drug concentration.

CONCLUSIONS

Timing of TFV gel application relative to sex significantly impacts drug levels. BAT dosing or sustained delivery may be optimal for preexposure prophylaxis.

Single oral dose of maraviroc does not prevent ex-vivo HIV infection of rectal mucosa in HIV-1 negative human volunteers

OBJECTIVE

Maraviroc (MVC) is a potential candidate for 'on demand' preexposure prophylaxis. In the present study, we evaluated the efficacy of a single oral dose of MVC to prevent ex-vivo HIV-1 infection of rectal tissue in humans.

DESIGN AND METHODS

Eight HIV-1-negative healthy volunteers received a single oral dose of MVC (300 or 600 mg), and two additional volunteers received tenofovir disoproxil fumarate/emtricitabine (TDF/FTC, 300/200 mg) for 10 days. Rectal biopsies were performed prior to the ex-vivo challenge (day 0), at day 7 (4 h after MVC) or after 10 days with TDF/FTC. Rectal biopsies were infected ex-vivo, and viral inhibition and CCR5 occupancy was analyzed. MVC concentration in plasma and rectal tissue was measured just after biopsy and after viral incubation.

RESULTS

Ex-vivo rectal tissue protection with MVC was incomplete in all but two participants, whereas TDF/FTC avoided ex-vivo infection in the two controls. Median dose-normalized concentration of MVC was significantly higher in rectal tissue than in plasma (561.1 and 155.1 ng/ml, respectively). A significant loss of MVC during the virus incubation (about 60%) and a low CCR5 occupancy (approximately 45%) were detected in rectal cells.

CONCLUSIONS

An ex-vivo challenge with a single oral dose of MVC does not prevent ex-vivo infection of human rectal mucosa. The lack of prophylactic efficacy observed suggests that 'on demand' MVC preexposure prophylaxis would not prevent rectal HIV-1 transmission.

The Molecular Characterization of Intestinal Explant HIV Infection Using Polymerase Chain Reaction-Based Techniques

The ex vivo mucosal explant model is frequently used to test the efficacy of microbicides that have the potential for preventing HIV-1 transmission. The conventional assessment of product efficacy has been the extent of HIV-1 p24 suppression in supernatant fluids sampled up to day 14 after HIV-1 challenge ex vivo. The purpose of this study was to determine if measurement of HIV-1 nucleic acids by real-time PCR and HIV-1 integration by Alu-gag PCR provides advantages with regard to monitoring HIV-1 infection in explants. Rectal biopsies from HIV-1-negative individuals were challenged with 1 × 10(5) virions/ml of HIV-1BaL or HIV-1CH077 ex vivo. HIV-1 RNA and HIV-1 p24 in supernatant fluids and HIV-1 nucleic acids and integrated provirus in individual biopsies were measured at days 1-14 after infection. HIV-1 RNA and proviral DNA were measured by quantitative real-time PCR (qRT-PCR) while integrated virus was detected by Alu-gag PCR. Real-time PCR assays detecting HIV-1 DNA and RNA performed similarly provided that the infecting virus sequences were a good match with the sequences of the assay primers and probes. Increased HIV-1 nucleic acid levels and DNA integration were measurable on days 11 and 14 after infection. The magnitude of explant infection was similar after challenge with HIV-1BaL and HIV-1CH077, although the trajectory of infection was delayed in the HIV-1CH077-infected biopsies. In the majority of experiments, qRT-PCR did not appreciably shorten the time necessary to detect evidence of HIV-1 infection.

Preclinical assessments of vaginal microbicide candidate safety and efficacy

Sexually transmitted infections like HIV, HPV, and HSV-2, as well as unplanned pregnancy, take a huge toll on women worldwide. Woman-initiated multipurpose prevention technologies that contain antiviral/antibacterial drugs (microbicides) and a contraceptive to simultaneously target sexually transmitted infections and unplanned pregnancy are being developed to reduce these burdens. This review will consider products that are applied topically to the vagina. Rectally administered topical microbicides in development for receptive anal intercourse are outside the scope of this review. Microbicide and microbicide/contraceptive candidates must be rigorously evaluated in preclinical models of safety and efficacy to ensure that only candidates with favorable risk benefit ratios are advanced into human clinical trials. This review describes the comprehensive set of in vitro, ex vivo, and in vivo models used to evaluate the preclinical safety and antiviral efficacy of microbicide and microbicide/contraceptive candidates.

A compartmental pharmacokinetic evaluation of long-acting rilpivirine in HIV-negative volunteers for pre-exposure prophylaxis

Rilpivirine long-acting (RPV-LA) is a parenteral formulation enabling prolonged plasma exposure. We explored its multiple-compartment pharmacokinetics (PK) after a single dose, for pre-exposure prophylaxis. Sixty-six HIV-negative volunteers were enrolled: women received an intramuscular dose of 300, 600, or 1,200 mg, with plasma and genital levels measured to 84 days postdose; men receiving 600 mg had similar PK determined in plasma and rectum. Ex vivo antiviral activity of cervicovaginal lavage (CVL) was also assessed. After a single dose, RPV concentrations peaked at days 6-8 and were present in plasma and genital-tract fluid to day 84. Vaginal and male rectal tissue levels matched those in plasma. At the 1,200 mg dose, CVL showed greater antiviral activity, above baseline, at days 28 and 56. All doses were well tolerated. All doses gave prolonged plasma and genital-tract rilpivirine exposure. PK and viral inhibition of repeated doses will be important in further dose selection.