Efficacy of Carraguard for prevention of HIV infection in women in South Africa: a randomised, double-blind, placebo-controlled trial

Vaginal microbicides and their delivery platforms

INTRODUCTION

HIV type 1 infection, despite having fallen by one-third over the past decade, remains a global health concern affecting millions of individuals worldwide. A focal point in contemporary research aimed at global HIV prevention has been the development of safe and efficacious coitally dependent and coitally independent anti-HIV microbicides to curb heterosexual HIV transmission. Despite extensive research efforts to develop novel vaginal antiretroviral (ARV) formulations and intravaginal ring delivery systems, the clinical advancement of microbicides with improved safety, efficacy and tolerability has significantly lagged behind.

AREAS COVERED

This review focuses on the current status of both coitally dependent and coitally independent delivery platforms designed to increase user acceptability and clinical effectiveness of anti-HIV microbicides. The clinical failure of several vaginal microbicide candidates has propelled the field to mechanism-based ARV candidates that act more specifically on viral receptors, viral enzymes and host proteins. Consequently, improved vaginal microbicide delivery strategies that achieve uniform drug distribution with enhanced solubility, sustained drug release, improved product adherence with reduced dosing frequency and lack of effect on the vaginal mucosa and microbiota are being sought.

EXPERT OPINION

Clinical success with vaginal microbicides may best be achieved through the combined effects of ARV compounds that exhibit different mechanisms of action with potent activity against multidrug-resistant HIV and efficacious delivery systems.

Adherence challenges with drugs for pre-exposure prophylaxis to prevent HIV infection

BACKGROUND

There are 34 million people living with human immunodeficiency virus (HIV) worldwide and each year this number increases. Until a vaccine is discovered, the prevention of new HIV infections remains an urgent priority. Several trials studying the use of oral and topical agents for the prevention of HIV infection have already been completed. Adherence has proved to be a major challenge in achieving product efficacy.

AIM OF THE REVIEW

To provide the clinical pharmacist with an understanding of the oral pre-exposure prophylaxis (PrEP) and topical microbicide product pipeline whilst emphasizing the critical importance of adherence to these drugs to avert HIV infection.

METHODS

PubMed/Medline and the web-based clinical trials registry (ClinTrials.gov) were searched using appropriate key words. For the time period 1992-2013--all phase II and phase III safety and effectiveness studies--testing agents for prevention of HIV infection were included in the review. Efficacy estimates, adherence estimates and reported challenges with adherence were extracted.

RESULTS

Twenty-four phase II and III clinical trials were found during review. Of these, 20 trials have been completed, and six trials show effectiveness in preventing HIV infection. The majority of the successful trials were to oral PrEP and to date only one microbicide trial of a vaginal antiretroviral microbicide gel has showed effectiveness. Adherence to study product played a major role in trial outcomes and there are several reasons for non-adherence. These include high on-trial pregnancy rates, low trial retention rates, low participant perception of risk, participant characteristics such as age <25 years, single status, migratory partners and trial fatigue. Study product characteristics such as dosage form, dosing interval, as well as associated adverse events may also influence adherence.

CONCLUSION

Moderate to high adherence is critical to demonstrate efficacy of drugs for HIV prevention. For topical agents, intermittent use associated with coitus is more effective than daily use, particularly if sex is infrequent or partners migrant. For oral agents, daily use is effective but the motivation to use the drug and high risk perception is important. In serodiscordant couples, early initiation of highly active antiretroviral therapy in the infected partner affords almost complete protection to the negative partner. Drugs need to be tailored to the population at risk and availability of multiple drug options are important.

Biomedical HIV prevention research and epidemic control in Thailand: two sides of the same coin

For a country with a moderate adult HIV prevalence of just over 1% in 2012, Thailand is widely perceived as having made some extraordinary contributions to the global management of the HIV/AIDS pandemic. It has been promoted as a model of effective HIV control and applauded for its leadership in providing access to antiretroviral treatment. Thailand has also received international recognition for its contribution to biomedical HIV prevention research, which is generally perceived as exceptional. In this paper, Thailand's global role model function as an example of effective HIV/AIDS control and high-quality biomedical HIV prevention research is re-evaluated against the background of currently available data and more recent insights. The results indicate that Thailand's initial response in raising the level of the political significance of HIV/AIDS was indeed extraordinary, which probably prevented a much larger epidemic from occurring. However, this response transpired in unusual extraconstitutional circumstances and its effectiveness declined once the country returned to political normalcy. Available data confirm the country's more than exceptional contribution to biomedical HIV prevention research. Thailand has made a huge contribution to the global management and control of the HIV/AIDS pandemic.

Attitudes towards microbicide use for bacterial vaginosis in pregnancy

Background Bacterial vaginosis (BV) is the most common reproductive tract infection (RTI) and is a significant risk factor for preterm birth. Microbicides could be an option for the prevention and treatment of BV in pregnancy, and understanding use of the product will be crucial. The present study explored attitudes of women in the third trimester of pregnancy regarding topical microbicide use for the prevention and treatment of BV.

METHODS

Twenty-six women in their third trimester were interviewed regarding their knowledge and beliefs about RTIs during pregnancy and attitudes concerning the use of topical microbicides for prevention and treatment of BV.

RESULTS

Participants had a mean age of 24.9 years, were largely under-represented minorities and the majority had had past pregnancies. Participants had knowledge and experience with RTIs but not BV. They were open to the use of microbicides for prevention or treatment of BV, but believed that women requiring treatment would be more motivated. Rationales for acceptability were most commonly related to the baby's health. Practical issues that may interfere with use were often, but not always, related to pregnancy. There was a range of attitudes about partner involvement in decision-making and the practicalities of product use.

CONCLUSION

Pregnant women are knowledgeable about RTIs but not necessarily BV. The women in this study found microbicide use acceptable, particularly for treatment. To improve acceptability and use, education would be needed about BV and possible complications, how to overcome practical problems and the value of involving partners in the decision.

Designing preclinical perceptibility measures to evaluate topical vaginal gel formulations: relating user sensory perceptions and experiences to formulation properties

Abstract The effectiveness of any biomedical prevention technology relies on both biological efficacy and behavioral adherence. Microbicide trials have been hampered by low adherence, limiting the ability to draw meaningful conclusions about product effectiveness. Central to this problem may be an inadequate conceptualization of how product properties themselves impact user experience and adherence. Our goal is to expand the current microbicide development framework to include product "perceptibility," the objective measurement of user sensory perceptions (i.e., sensations) and experiences of formulation performance during use. For vaginal gels, a set of biophysical properties, including rheological properties and measures of spreading and retention, may critically impact user experiences. Project LINK sought to characterize the user experience in this regard, and to validate measures of user sensory perceptions and experiences (USPEs) using four prototype topical vaginal gel formulations designed for pericoital use. Perceptibility scales captured a range of USPEs during the product application process (five scales), ambulation after product insertion (six scales), and during sexual activity (eight scales). Comparative statistical analyses provided empirical support for hypothesized relationships between gel properties, spreading performance, and the user experience. Project LINK provides preliminary evidence for the utility of evaluating USPEs, introducing a paradigm shift in the field of microbicide formulation design. We propose that these user sensory perceptions and experiences initiate cognitive processes in users resulting in product choice and willingness-to-use. By understanding the impact of USPEs on that process, formulation development can optimize both drug delivery and adherence.

Animal models for microbicide safety and efficacy testing

PURPOSE OF REVIEW

Early studies have cast doubt on the utility of animal models for predicting success or failure of HIV-prevention strategies, but results of multiple human phase 3 microbicide trials, and interrogations into the discrepancies between human and animal model trials, indicate that animal models were, and are, predictive of safety and efficacy of microbicide candidates.

RECENT FINDINGS

Recent studies have shown that topically applied vaginal gels, and oral prophylaxis using single or combination antiretrovirals are indeed effective in preventing sexual HIV transmission in humans, and all of these successes were predicted in animal models. Further, prior discrepancies between animal and human results are finally being deciphered as inadequacies in study design in the model, or quite often, noncompliance in human trials, the latter being increasingly recognized as a major problem in human microbicide trials.

SUMMARY

Successful microbicide studies in humans have validated results in animal models, and several ongoing studies are further investigating questions of tissue distribution, duration of efficacy, and continued safety with repeated application of these, and other promising microbicide candidates in both murine and nonhuman primate models. Now that we finally have positive correlations with prevention strategies and protection from HIV transmission, we can retrospectively validate animal models for their ability to predict these results, and more importantly, prospectively use these models to select and advance even safer, more effective, and importantly, more durable microbicide candidates into human trials.

Women and HIV in Sub-Saharan Africa

Thirty years since the discovery of HIV, the HIV pandemic in sub-Saharan Africa accounts for more than two thirds of the world's HIV infections. Southern Africa remains the region most severely affected by the epidemic. Women continue to bear the brunt of the epidemic with young women infected almost ten years earlier compared to their male counterparts. Epidemiological evidence suggests unacceptably high HIV prevalence and incidence rates among women. A multitude of factors increase women's vulnerability to HIV acquisition, including, biological, behavioral, socioeconomic, cultural and structural risks. There is no magic bullet and behavior alone is unlikely to change the course of the epidemic. Considerable progress has been made in biomedical, behavioral and structural strategies for HIV prevention with attendant challenges of developing appropriate HIV prevention packages which take into consideration the socioeconomic and cultural context of women in society at large.

High risk sexual behaviors are associated with sexual violence among a cohort of women in Durban, South Africa

Background

Studies show Gender Based Violence (GBV) to be significantly associated with risky sexual behaviour. In South Africa the incidence of GBV is reportedly high, and there is a strong argument for GBV to be a driver of HIV infection rates. This study describes the prevalence of Forced Sex (FS) experiences of women who enrolled into an HIV biomedical intervention study, and its association with risky sexual behaviour.

Findings

In this study, sociodemographic and behavioural data from women enrolled in the Carraguard™ trial, were assessed in relation to FS using logistic regression. The results indicated that 193/1485 (13%) of women reported ever experiencing FS at the screening visit. Women who were 30 years and older; reported having sex for cash; multiple partners; changing partners during the trial; inconsistent condom use during the trial; and 3 or more sex acts in the 2 weeks prior to screening, were significantly more likely to have experienced forced sex.

Conclusions

The results of this study are broadly consistent with those found in other studies and are similar in profile to women at higher risk for HIV acquisition in our setting. This study indicates a need for GBV prevention to be integrated with HIV prevention programmes.

Use of the dye stain assay and ultraviolet light test for assessing vaginal insertion of placebo-filled applicators before and after sex

BACKGROUND

Applicator dye staining and ultraviolet (UV) light have been used in trials to measure adherence, but not in the setting of before and after sex gel dosing (BAT-24). This study was designed to determine if semen or presex gel dosing impacts the sensitivity and specificity of a dye stain assay (DSA) for measuring vaginal insertion of placebo-filled applicators with BAT-24 dosing.

METHODS

Healthy monogamous couples received Microlax-type applicators (Tectubes, Åstorp, Sweden) filled with hydroxyethylcelluose placebo gel. Women were instructed to vaginally insert 1 dose of gel before and a second dose after sex and to return applicators within 48 hours after sex. Applicators were stained to detect semen, followed by UV then DSA, and scored by 2 readers. Positive and negative controls were randomly included in applicator batches.

RESULTS

Fifteen couples completed the study. Each woman returned at least 6 applicators over a 30-day period. The sensitivity for insertion of postsex applicators was higher for UV (97%) compared with DSA (90%), and the specificity was similar (≥96%). For presex applicators, the sensitivity and specificity were higher for DSA (100%) compared with UV testing (87% sensitivity, 96% specificity). Among returned postsex applicators, 95% tested positive by UV compared with 87% by DSA. Agreement between readers was significantly better on the presex applicators for DSA than for UV, and for postsex readings, agreement was less than half that for UV, although the results were not statistically significant.

CONCLUSIONS

Applicator tests are feasible for measuring adherence in trials with gel dosing before and after sex.

Evaluation of 3 approaches for assessing adherence to vaginal gel application in clinical trials

BACKGROUND

Accurate measurement of adherence to product use is an ongoing challenge in microbicide trials.

METHODS

We compared adherence estimates using 2 applicator tests (a dye stain assay [DSA] and an ultraviolet light assay [UVA]), the Wisebag (an applicator container that electronically tracks container openings), and self-reported adherence (ability, frequency, and percent missed doses). Healthy, HIV-negative, nonpregnant US women aged 23 to 45 years received a Wisebag and 32 applicators filled with placebo gel were instructed to insert 1 applicator daily for 30 days, returned the Wisebag and all applicators, and completed an exit interview. Emptied applicators were tested by UVA and then DSA, and scored by 2 blinded readers. Positive and negative controls were randomly included in applicator batches.

RESULTS

Among 42 women enrolled, 39 completed the study. Both DSA and UVA yielded similar sensitivity (97% and 95%) and specificity (79% and 79%). Two participants had fully inoperable Wisebags, and 9 had partially inoperable Wisebags. The proportion of participants considered to have high adherence (≥80%) varied: 43% (Wisebag), 46% (UVA), 49% (DSA), and 62% to 82% (self-reports). For estimating high adherence, Wisebag had a sensitivity of 76% (95% confidence interval, 50%-93%) and a specificity of 85% (95% confidence interval, 62%-97%) compared with DSA. Although 28% of participants reported forgetting to open the Wisebag daily, 59% said that it helped them remember gel use.

CONCLUSIONS

Dye stain assay and UVA performed similarly. Compared with these tests, self-reports overestimated and Wisebag underestimated adherence. Although Wisebag may encourage gel use, the applicator tests currently seem more useful for measuring use in clinical trials.

Evaluation of PD 404,182 as an anti-HIV and anti-herpes simplex virus microbicide

PD 404,182 (PD) is a synthetic compound that was found to compromise HIV integrity via interaction with a nonenvelope protein viral structural component (A. M. Chamoun et al., Antimicrob. Agents Chemother. 56:672-681, 2012). The present study evaluates the potential of PD as an anti-HIV microbicide and establishes PD's virucidal activity toward another pathogen, herpes simplex virus (HSV). We show that the anti-HIV-1 50% inhibitory concentration (IC50) of PD, when diluted in seminal plasma, is ∼1 μM, similar to the IC50 determined in cell culture growth medium, and that PD retains full anti-HIV-1 activity after incubation in cervical fluid at 37°C for at least 24 h. In addition, PD is nontoxic toward vaginal commensal Lactobacillus species (50% cytotoxic concentration [CC50], >300 μM), freshly activated human peripheral blood mononuclear cells (CC50, ∼200 μM), and primary CD4(+) T cells, macrophages, and dendritic cells (CC50, >300 μM). PD also exhibited high stability in pH-adjusted Dulbecco's phosphate-buffered saline with little to no activity loss after 8 weeks at pH 4 and 42°C, indicating suitability for formulation for transportation and storage in developing countries. Finally, for the first time, we show that PD inactivates herpes simplex virus 1 (HSV-1) and HSV-2 at submicromolar concentrations. Due to the prevalence of HSV infection, the ability of PD to inactivate HSV may provide an additional incentive for use as a microbicide. The ability of PD to inactivate both HIV-1 and HSV, combined with its low toxicity and high stability, warrants additional studies for the evaluation of PD's microbicidal candidacy in animals and humans.

Toward early safety alert endpoints: exploring biomarkers suggestive of microbicide failure

Several microbicides, including nonoxynol-9 (N-9) and cellulose sulfate (CS), looked promising during early trials but failed in efficacy trials. We aimed to identify Phase I mucosal safety endpoints that might explain that failure. In a blinded, randomized, parallel trial, 60 healthy premenopausal sexually abstinent women applied Universal HEC placebo, 6% CS or 4% N-9 gel twice daily for 13½ days. Endpoints included immune biomarkers in cervicovaginal lavage (CVL) and endocervical cytobrushes, inflammatory infiltrates in vaginal biopsies, epithelial integrity by naked eye, colposcopy, and histology, CVL anti-HIV activity, vaginal microflora, pH, and adverse events. Twenty women enrolled per group. Soluble/cellular markers were similar with CS and placebo, except secretory leukocyte protease inhibitor (SLPI) levels decreased in CVL, and CD3(+) and CD45(+) cells increased in biopsies after CS use. Increases in interleukin (IL)-8, IL-1, IL-1RA, and myeloperoxidase (MPO) and decreases in SLPI were significant with N-9. CVL anti-HIV activity was significantly higher during CS use compared to N-9 or placebo. CS users tended to have a higher prevalence of intermediate Nugent score, Escherichia coli, and Enterococcus and fewer gram-negative rods. Most Nugent scores diagnostic for bacterial vaginosis were in N-9 users. All cases of histological inflammation or deep epithelial disruption occurred in N-9 users. While the surfactant N-9 showed obvious biochemical and histological signs of inflammation, more subtle changes, including depression of SLPI, tissue influx of CD45(+) and CD3(+) cells, and subclinical microflora shifts were associated with CS use and may help to explain the clinical failure of nonsurfactant microbicides.

Multipurpose prevention technologies: products in development

Multipurpose prevention technologies (MPTs) are broadly defined as products capable of simultaneously addressing multiple sexual and reproductive health needs including unintended pregnancy, STIs including HIV-1, and other reproductive tract infections. MPTs have been discussed for a few decades but little product development has occurred. With the recent proof-of-concept that a topically applied antiretroviral (ARV) can effectively reduce sexual transmission of HIV-1 (tenofovir 1% gel) the impetus to develop MPTs is gaining momentum. Products currently in development are broadly categorized as either long-acting or on-demand. Long-acting MPTs include intravaginal rings (IVRs) and long-acting injectable products. Several IVR MPTs are under development including one designed to release tenofovir to prevent transmission of HIV-1 and levonorgestrel (LNG) to prevent unintended pregnancy over a 90-day period. Another MPT IVR under development is designed to release the ARV dapivirine and LNG for 2 months. Long-acting injectable pre-exposure prophylaxis (PrEP) formulations of rilpivirine (TMC278) and GSK1265744 have entered clinical evaluation and could form the basis of long-acting injectable products for HIV-1 prevention and prevention of unintended pregnancy. On-demand products include TFV 1% gel (HIV-1/HSV-2 prevention), a zinc/carrageenan zinc gel (HIV-1/HSV-2 prevention), and the SILCS diaphragm administered with TFV 1% gel. Significant technical, funding, and regulatory hurdles must be overcome to develop most MPTs; however, the significant reproductive health benefits to many women around the world should provide motivation to overcome these hurdles. This article is based on a presentation at the "Product Development Workshop 2013: HIV and Multipurpose Prevention Technologies", held in Arlington, Virginia on February 21-22, 2013. It forms part of a special supplement to Antiviral Research.

Rectal pre-exposure prophylaxis (PrEP)

Rectal pre-exposure prophylaxis (PrEP) will be a critical component of HIV prevention products due to the prevalence of unprotected receptive anal intercourse among men who have sex with men and heterosexual couples. Given the biological considerations of this compartment and the complexity of HIV infection, design of a successful rectal microbicide product faces a number of challenges. Important information is being compiled to begin to address deficits in knowledge toward design of rectal PrEP products for men and women. Aspects of formulation development and preclinical and clinical evaluation of rectal products studied to date are summarized in this review. This article is based on a presentation at the "Product Development Workshop 2013: HIV and Multipurpose Prevention Technologies," held in Arlington, Virginia on February 21-22, 2013. It forms part of a special supplement to Antiviral Research.

Microbicides for the prevention of sexually transmitted HIV infection

The impetus for, and efforts in the past 20 years toward a women-initiated method for preventing sexual transmission of HIV has been previously well described. To date, four classes of topical agents categorized by mechanism of action as: surfactants, buffers, cell entry blockers and antiretroviral agents have undergone advanced clinical testing. Thus far, only coitally linked use of 1% tenofovir gel has demonstrated moderate effectiveness in preventing HIV and HSV-2 infection and has generated renewed hope for microbicide development. Studies of new antiviral agents, novel delivery mechanisms and combination/multipurpose products that address challenges of adherence and enhance the effectiveness of tenofovir gel are already underway to further enhance sexual and reproductive health needs of men and women and efforts to prevent HIV infection.

Clinical use of vaginal or rectally applied microbicides in patients suffering from HIV/AIDS

Microbicides, primarily used as topical pre-exposure prophylaxis, have been proposed to prevent sexual transmission of HIV. This review covers the trends and challenges in the development of safe and effective microbicides to prevent sexual transmission of HIV Initial phases of microbicide development used such surfactants as nonoxynol-9 (N-9), C13G, and sodium lauryl sulfate, aiming to inactivate the virus. Clinical trials of microbicides based on N-9 and C31G failed to inhibit sexual transmission of HIV. On the contrary, N-9 enhanced susceptibility to sexual transmission of HIV-1. Subsequently, microbicides based on polyanions and a variety of other compounds that inhibit the binding, fusion, or entry of virus to the host cells were evaluated for their efficacy in different clinical setups. Most of these trials failed to show either safety or efficacy for prevention of HIV transmission. The next phase of microbicide development involved antiretroviral drugs. Microbicide in the form of 1% tenofovir vaginal gel when tested in a Phase IIb trial (CAPRISA 004) in a coitally dependent manner revealed that tenofovir gel users were 39% less likely to become HIV-infected compared to placebo control. However, in another trial (VOICE MTN 003), tenofovir gel used once daily in a coitally independent mode failed to show any efficacy to prevent HIV infection. Tenofovir gel is currently in a Phase III safety and efficacy trial in South Africa (FACTS 001) employing a coitally dependent dosing regimen. Further, long-acting microbicide-delivery systems (vaginal ring) for slow release of such antiretroviral drugs as dapivirine are also undergoing clinical trials. Discovering new markers as correlates of protective efficacy, novel long-acting delivery systems with improved adherence in the use of microbicides, discovering new compounds effective against a broad spectrum of HIV strains, developing multipurpose technologies incorporating additional features of efficacy against other sexually transmitted infections, and contraception will help in moving the field of microbicide development forward.

Pregnancy incidence and risk factors among women participating in vaginal microbicide trials for HIV prevention: systematic review and meta-analysis

Introduction

Pregnancy is contraindicated in vaginal microbicide trials for the prevention of HIV infection in women due to the unknown maternal and fetal safety of the microbicides. Women who become pregnant are taken off the microbicide during pregnancy period but this result in reduction of the power of the trials. Strategies to reduce the pregnancy rates require an understanding of the incidence and associated risk factors of pregnancy in microbicide trials. This systematic review estimates the overall incidence rate of pregnancy in microbicide trials and describes the associated risk factors.

Methods

A comprehensive literature search was carried out to identify eligible studies from electronic databases and other sources. Two review authors independently selected studies and extracted relevant data from included studies. Meta-analysis of incidence rates of pregnancy was carried out and risk factors of pregnancy were reported narratively.

Results

Fifteen studies reporting data from 10 microbicide trials (N=27,384 participants) were included. A total of 4,107 participants (15.0%) fell pregnant and a meta-analysis of incidence rates of pregnancy from 8 microbicide trials (N=25,551) yielded an overall incidence rate of 23.37 (95%CI: 17.78 to 28.96) pregnancies per 100 woman-years. However, significant heterogeneity was detected. Hormonal injectable, intra-uterine device (IUD) or implants or sterilization, older age, more years of education and condom use were associated with lower pregnancy. On the other hand, living with a man, history of pregnancy, self and partner desire for future baby, oral contraceptive use, increased number of unprotected sexual acts and inconsistent use of condoms were associated with higher pregnancy.

Conclusions

The incidence rate of pregnancy in microbicide trials is high and strategies for its reduction are urgently required in order to improve the sample size and power of these trials.

Safety, adherence and acceptability of intermittent tenofovir/emtricitabine as HIV pre-exposure prophylaxis (PrEP) among HIV-uninfected Ugandan volunteers living in HIV-serodiscordant relationships: a randomized, clinical trial

Background

Efficacy of oral pre-exposure prophylaxis (PrEP) in prevention of HIV acquisition has been evaluated using a daily regimen. However, adherence to long term daily medication is rarely perfect. Intermittent regimen may be a feasible alternative. Preclinical studies have demonstrated effectiveness of intermittent PrEP in SHIV prevention among animals. However, little is known about intermittent PrEP regimens.

Design

Seventy two HIV-uninfected volunteers in HIV serodiscordant couple relationships in Uganda were randomly assigned to receive daily oral Tenofovir/Emtricitabine (TDF/FTC-Truvada) or placebo, or intermittent (Monday, Friday and within 2 hours after sex, not to exceed one dose per day) oral TDF/FTC or placebo in a 2:1:2:1 ratio. Volunteers and study staff were blinded to drug assignment, but not to regimen assignment.

Methods

Volunteers were followed for 4 months after randomization, with monthly clinical and laboratory safety assessments and comprehensive HIV risk reduction services. Adherence was monitored using medication event monitoring system (MEMS) and self-report. Sexual activity data were collected via daily short text message (SMS) and self-report. HIV-specific immune responses were assessed by IFN-γ ELISPOT.

Results

Both daily and intermittent oral TDF/FTC regimens were well tolerated. Median MEMS adherence rates were 98% (IQR: 93-100) for daily PrEP regimen, 91% (IQR: 73-97) for fixed intermittent dosing and 45% (IQR: 20-63) for post-coital dosing. SMS response rate was 74%, but increased to 80% after excluding server outages; results may have been affected by the novelty of this measure. The majority of volunteers expressed willingness with no particular preference for either regimen.

Conclusions

Both daily and intermittent oral PrEP dosing regimens were safe. Adherence was high for daily and fixed intermittent dosing; post-coital dosing was associated with poor adherence. Fixed intermittent PrEP regimens may be feasible especially if a minimum effective drug concentration correlating with HIV prevention can be achieved with this dosing.

Registration

Clinicaltrials.gov number NCT00931346

Components of the cultivated red seaweed Chondrus crispus enhance the immune response of Caenorhabditis elegans to Pseudomonas aeruginosa through the pmk-1, daf-2/daf-16, and skn-1 pathways

Marine macroalgae are rich in bioactive compounds that can, when consumed, impart beneficial effects on animal and human health. The red seaweed Chondrus crispus has been reported to have a wide range of health-promoting activities, such as antitumor and antiviral activities. Using a Caenorhabditis elegans infection model, we show that C. crispus water extract (CCWE) enhances host immunity and suppresses the expression of quorum sensing (QS) and the virulence factors of Pseudomonas aeruginosa (strain PA14). Supplementation of nematode growth medium with CCWE induced the expression of C. elegans innate immune genes, such as irg-1, irg-2, F49F1.6, hsf-1, K05D8.5, F56D6.2, C29F3.7, F28D1.3, F38A1.5 ZK6.7, lys-1, spp-1, and abf-1, by more than 2-fold, while T20G5.7 was not affected. Additionally, CCWE suppressed the expression of PA14 QS genes and virulence factors, although it did not affect the growth of the bacteria. These effects correlated with a 28% reduction in the PA14-inflicted killing of C. elegans. Kappa-carrageenan (K-CGN), a major component of CCWE, was shown to play an important role in the enhancement of host immunity. Using C. elegans mutants, we identified that pmk-1, daf-2/daf-16, and skn-1 are essential in the K-CGN-induced host immune response. In view of the conservation of innate immune pathways between C. elegans and humans, the results of this study suggest that water-soluble components of C. crispus may also play a health-promoting role in higher animals and humans.

Lost in translation: assessing effectiveness of focus group questioning techniques to develop improved translation of terminology used in HIV prevention clinical trials

Introduction

Achieving participant comprehension has proven to be one of the most difficult, practical, and ethical challenges of HIV prevention clinical trials. It becomes even more challenging when local languages do not have equivalent scientific and technical vocabularies, rendering communication of scientific concepts in translated documents extremely difficult. Even when bilingual lexicons are developed, there is no guarantee that participants understand the terminology as translated.

Methods

We conducted twelve focus groups with women of reproductive age in Mwanza, Tanzania to explore the effectiveness of four questioning techniques for: (1) assessing participants' familiarity with existing technical terms and concepts, (2) generating a list of acceptable technical and non-technical terms, (3) testing our definitions of technical terms, and (4) verifying participants' preferences for terms. Focus groups were transcribed, translated, and qualitatively analyzed.

Results and Discussion

A translation process that uses all four questioning techniques in a step-wise approach is an effective way to establish a baseline understanding of participants' familiarity with research terms, to develop and test translatable definitions, and to identify participants' preferred terminology for international HIV clinical research. This may help to ensure that important concepts are not “lost in translation.” The results emphasize the importance of using a variety of techniques depending on the level of participant familiarity with research concepts, the existence of colloquial or technical terms in the target language, and the inherent complexity of the terms.

Topical microbicides--what's new?

Topical microbicides are an important, promising but complex HIV prevention technology under development. After 11 disappointing effectiveness trial outcomes of 6 candidate products (some tested as multiple doses and formulations) over the past 20 years, there is renewed optimism that a safe and effective microbicide will soon be available if the recent success of coitally linked use of the antiretroviral-based microbicide, 1% tenofovir gel, is confirmed. Studies of new antiviral agents, novel delivery mechanisms, and combination/multipurpose products that address challenges of adherence, enhance the effectiveness of tenofovir gel, and address sexual and reproductive health needs of men and women, including preventing HIV infection, are already underway.

A modified zinc acetate gel, a potential nonantiretroviral microbicide, is safe and effective against simian-human immunodeficiency virus and herpes simplex virus 2 infection in vivo

We previously showed that a prototype gel comprising zinc acetate (ZA) in carrageenan (CG) protected mice against vaginal and rectal herpes simplex virus 2 (HSV-2) challenge as well as macaques against vaginal simian-human immunodeficiency virus reverse transcriptase (SHIV-RT) challenge. In this work, we modified buffers and cosolvents to obtain a stable, nearly iso-osmolal formulation and evaluated its safety and efficacy against SHIV-RT and HSV-2. In vitro toxicity to lactobacilli and Candida albicans was determined. Macaques were given daily doses of ZA and CG (ZA/CG) or CG alone vaginally for 14 days and challenged with SHIV-RT 24 h later. Mice were challenged vaginally or rectally with HSV-2 immediately after a single gel treatment to measure efficacy or vaginally 12 h after daily gel treatment for 7 days to evaluate the gel's impact on susceptibility to HSV-2 infection. The modified ZA/CG neither affected the viability of lactobacilli or C. albicans nor enhanced vaginal HSV-2 infection after daily ZA/CG treatment. Vaginal SHIV-RT infection of macaques was reduced by 66% (P = 0.006) when macaques were challenged 24 h after the last dose of gel. We observed 60% to 80% uninfected mice after vaginal (P < 0.0001) and rectal (P = 0.008) high-dose HSV-2 challenge. The modified ZA/CG gel is safe and effective in animal models and represents a potential candidate to limit the transmission of HIV and HSV-2.

Postintegration HIV-1 infection of cervical epithelial cells mediates contact-dependent productive infection of T cells

The female genital epithelium plays a protective role against invading pathogens; however, sexual transmission of human immunodeficiency virus type 1 (HIV-1) still occurs in healthy women. To model virus-cell interactions in this barrier during sexual transmission, we studied the uptake and infection of ectocervical and endocervical cell lines with cell-free fluorescent protein-expressing recombinant HIV-1 carrying primary transmitted/founder envelope genes. We observed that a subset of both the ectocervical and endocervical epithelial cells become productively infected with cell-free HIV-1 in a CD4-independent manner. In addition, the ability of the semen-derived enhancer of virus infection (SEVI) to enhance virus-epithelial cell interactions was studied. This infection is increased approximately 2-5 fold when inoculation occurs in the presence of SEVI fibrils. Once infected, the epithelial cells are capable of transmitting the virus to target CD4 T cells in coculture in a contact-dependent manner that uses conventional CD4- and coreceptor-dependent entry. The infection of target CD4 T cells only occurs when de novo HIV-1 is produced within the epithelial cells. These findings suggest that a subset of cervical epithelial cells may be actively involved in establishing a systemic HIV infection and should be a target when designing prevention strategies to protect against HIV-1 sexual transmission.

Use of human mucosal tissue to study HIV-1 pathogenesis and evaluate HIV-1 prevention modalities

The use of human mucosal tissue models is an important tool advancing our understanding of the specific mechanisms of sexual HIV transmission. Despite 30 years of study, major gaps remain, including how HIV-1 transverses the epithelium and the identity of the early immune targets (gate keepers). Because defining HIV-1 transmission in vivo is difficult, mucosal tissue is being used ex vivo to identify key steps in HIV-1 entry and early dissemination. Elucidating early events of HIV-1 infection will help us develop more potent and specific HIV-1 preventatives such as microbicides and vaccines. Mucosal tissue has been incorporated into testing regimens for antiretroviral drugs and monoclonal antibodies. The use of mucosal tissue recapitulates the epithelium and immune cells that would be exposed in vivo to virus and drug. This review will discuss the use of mucosal tissue to better understand HIV-1 pathogenesis and prevention modalities.

An evaluation of methods to improve the reporting of adherence in a placebo gel trial in Andhra Pradesh, India

Female sex workers (FSWs) were recruited for a 4-month placebo vaginal gel trial in Nellore, India. Two experiments explored if prior knowledge of biomarkers for unprotected sex and insertion of gel applicators would yield more accurate self-reports. A third experiment compared self-reports of gel use and adherence levels between FSWs randomly assigned to interactive voice response survey (IVRS) and those assigned to paper diaries. Prior knowledge of biomarkers did not improve accuracy of self-reported condom or gel use, nor did it affect actual adherence. Of those who tested positive for the presence of semenogelin in the vagina, 76% reported no unprotected sex in the previous 48 h. Overall, women reported using gel on 90% of days whereas the biomarker indicated gel use on fewer than 50% of days. Compliance to IVRS was low, despite familiarity with mobile phone technology. Additional explorations with other populations are needed.

The promise of pre-exposure prophylaxis with antiretroviral drugs to prevent HIV transmission: a review

PURPOSE OF REVIEW

Public health experts are wrestling with how to translate recent scientific findings from pre-exposure prophylaxis (PrEP) effectiveness trials into real-world programmes. This review summarizes clinical trial findings on oral and topical PrEP, discusses how decision-makers can evaluate the place of PrEP within combination prevention and highlights anticipated developments that could be important in future HIV-prevention strategies.

RECENT FINDINGS

PrEP taken daily as oral tablets to create systemic protection has been found to be effective in the Pre-Exposure Prophylaxis Initiative (iPrEx), Partners' PrEP and TDF2 trials, but not in Fem-PrEP or the Vaginal and Oral Interventions to Control the Epidemic (VOICE) tenofovir arm. Tenofovir gel for topical protection was effective in CAPRISA 004 when used peri-coitally but not in VOICE with daily use. These findings underscore the importance of adherence to achieve adequate drug levels and the potential additive role of PrEP within combination prevention. Pivotal phase III trials are underway of the dapivirine ring, whereas phase I trials of injectable formulations show promise.

SUMMARY

Antiretroviral-based HIV-prevention programmes should be tailored to those most likely to be adherent, providing them with state-of-the-art counselling and support to achieve high adherence during the time period of use. Long-acting products, if found well tolerated and effective, could be ideal for overcoming adherence challenges.

Microbicide clinical trial adherence: insights for introduction

After two decades of microbicide clinical trials it remains uncertain if vaginally- delivered products will be clearly shown to reduce the risk of HIV infection in women and girls. Furthermore, a microbicide product with demonstrated clinical efficacy must be used correctly and consistently if it is to prevent infection. Information on adherence that can be gleaned from microbicide trials is relevant for future microbicide safety and efficacy trials, pre-licensure implementation trials, Phase IV post-marketing research, and microbicide introduction and delivery. Drawing primarily from data and experience that has emerged from the large-scale microbicide efficacy trials completed to-date, the paper identifies six broad areas of adherence lessons learned: (1) Adherence measurement in clinical trials, (2) Comprehension of use instructions/Instructions for use, (3) Unknown efficacy and its effect on adherence/Messages regarding effectiveness, (4) Partner influence on use, (5) Retention and continuation and (6) Generalizability of trial participants' adherence behavior. Each is discussed, with examples provided from microbicide trials. For each of these adherence topics, recommendations are provided for using trial findings to prepare for future microbicide safety and efficacy trials, Phase IV post-marketing research, and microbicide introduction and delivery programs.

Polyanionic candidate microbicides accelerate the formation of semen-derived amyloid fibrils to enhance HIV-1 infection

Polyanionic candidate microbicides, including cellulose sulfate, carrageenan, PRO 2000, were proven ineffective in preventing HIV-1 transmission and even cellulose sulfate showed increased risk of HIV acquisition in the Phase III efficacy trials. Semen plays critical roles in HIV-1 sexual transmission. Specifically, amyloid fibrils formed by fragments of prostatic acidic phosphatase (PAP) in semen termed semen-derived enhancer of virus infection (SEVI) could drastically enhance HIV-1 infection. Here we investigated the interaction between polyanions and PAP248-286, a prototype peptide of SEVI, to understand the possible cause of polyanionic candidate microbicides to fail in clinical trials. We found anionic polymers could efficiently promote SEVI fibril formation, most likely mediated by the natural electrostatic interaction between polyanions and PAP248-286, as revealed by acid native PAGE and Western blot. The overall anti-HIV-1 activity of polyanions in the presence or absence of PAP248-286 or semen was evaluated. In the viral infection assay, the supernatants of polyanions/PAP248-286 or polyanions/semen mixtures containing the free, unbound polyanionic molecules showed a general reduction in antiviral efficacy, while the pellets containing amyloid fibrils formed by the polyanion-bound PAP248-286 showed aggravated enhancement of viral infection. Collectively, from the point of drug-host protein interaction, our study revealed that polyanions facilitate SEVI fibril formation to promote HIV-1 infection, thus highlighting a molecular mechanism underlying the failure of polyanions in clinical trials and the importance of drug-semen interaction in evaluating the anti-HIV-1 efficacy of candidate microbicides.

Rectal transmission of transmitted/founder HIV-1 is efficiently prevented by topical 1% tenofovir in BLT humanized mice

Rectal microbicides are being developed to prevent new HIV infections in both men and women. We focused our in vivo preclinical efficacy study on rectally-applied tenofovir. BLT humanized mice (n = 43) were rectally inoculated with either the primary isolate HIV-1JRCSF or the MSM-derived transmitted/founder (T/F) virus HIV-1THRO within 30 minutes following treatment with topical 1% tenofovir or vehicle. Under our experimental conditions, in the absence of drug treatment we observed 50% and 60% rectal transmission by HIV-1JRCSF and HIV-1THRO, respectively. Topical tenofovir reduced rectal transmission to 8% (1/12; log rank p = 0.03) for HIV-1JRCSF and 0% (0/6; log rank p = 0.02) for HIV-1THRO. This is the first demonstration that any human T/F HIV-1 rectally infects humanized mice and that transmission of the T/F virus can be efficiently blocked by rectally applied 1% tenofovir. These results obtained in BLT mice, along with recent ex vivo, Phase 1 trial and non-human primate reports, provide a critically important step forward in the development of tenofovir-based rectal microbicides.

In vivo anti-herpes simplex virus activity of a sulfated derivative of Agaricus brasiliensis mycelial polysaccharide

Agaricus brasiliensis (syn. A. subrufescens), a basidiomycete fungus native to the Atlantic forest in Brazil, contains cell walls rich in glucomannan polysaccharides. The β-(1 → 2)-gluco-β-(1 → 3)-mannan was isolated from A. brasiliensis mycelium, chemically modified by sulfation, and named MI-S. MI-S has multiple mechanisms of action, including inhibition of herpes simplex virus (HSV) attachment, entry, and cell-to-cell spread (F. T. G. S. Cardozo, C. M. Camelini, A. Mascarello, M. J. Rossi, R. J. Nunes, C. R. Barardi, M. M. de Mendonça, and C. M. O. Simões, Antiviral Res. 92:108-114, 2011). The antiherpetic efficacy of MI-S was assessed in murine ocular, cutaneous, and genital infection models of HSV. Groups of 10 mice were infected with HSV-1 (strain KOS) or HSV-2 (strain 333). MI-S was given either topically or by oral gavage under various pre- and posttreatment regimens, and the severity of disease and viral titers in ocular and vaginal samples were determined. No toxicity was observed in the uninfected groups treated with MI-S. The topical and oral treatments with MI-S were not effective in reducing ocular disease. Topical application of MI-S on skin lesions was also not effective, but cutaneously infected mice treated orally with MI-S had significantly reduced disease scores (P < 0.05) after day 9, suggesting that healing was accelerated. Vaginal administration of MI-S 20 min before viral challenge reduced the mean disease scores on days 5 to 9 (P < 0.05), viral titers on day 1 (P < 0.05), and mortality (P < 0.0001) in comparison to the control groups (untreated and vehicle treated). These results show that MI-S may be useful as an oral agent to reduce the severity of HSV cutaneous and mucosal lesions and, more importantly, as a microbicide to block sexual transmission of HSV-2 genital infections.

Acceptability in microbicide and PrEP trials: current status and a reconceptualization

PURPOSE OF REVIEW

Assessment of acceptability is a central component of most oral PrEP and microbicide trials. In this paper we review current definitions and frameworks employed in acceptability research, discuss findings from recent studies of product acceptability and summarize trends in acceptability research. We conclude by offering a new framework for investigating product acceptability within clinical trials, one which considers product acceptability to be conceptually distinct from adherence.

RECENT FINDINGS

Although numerous studies have investigated product acceptability, a consensus is lacking regarding the definition and operationalization of the concept. In addition fewer than half of the studies reviewed investigated actual candidate products. To the extent that an overall measure of acceptability is considered, the consensus is that most participants find the products acceptable. However, it is the rare study that investigates whether product adherence is associated with acceptability.

SUMMARY

Given that adherence is critical to the success of clinical trials, it is important to identify the extent to which acceptability is a factor in product usage and to ascertain which dimensions of acceptability - product attributes, dosing regimen, delivery mechanism, use attributes, partner's attitudes, effect of product on the sexual encounter, product-related norms - if any, affect adherence.

Women with pregnancies had lower adherence to 1% tenofovir vaginal gel as HIV preexposure prophylaxis in CAPRISA 004, a phase IIB randomized-controlled trial

Background

Antiretroviral prophylaxis may be a critical strategy to reduce periconception HIV transmission. Maximizing the benefit of periconception pharmacologic HIV risk-reduction requires an understanding of the links between pregnancy and adherence to this prevention strategy.

Methods

We assessed study gel adherence among women with pregnancies compared to women without pregnancies enrolled in the CAPRISA 004 phase IIB trial of 1% vaginal tenofovir gel. Pregnancy was assessed with monthly urine tests. Adherence was measured monthly and defined as proportion of sex acts covered by two returned, used applicators based on pre- and post-coital dosing. High adherence was defined as a median adherence score of >80%, that is, more than 80% of sex acts were covered by two applications of study gel. A multivariate generalized estimating equations (GEE) model with a binomial distribution was used to assess covariates associated with high adherence (>80%) over time. Median adherence before and after pregnancy was compared using Wilcoxon signed rank test.

Results

Among 868 women, 53 had at least 1 pregnancy (4.06 per 100 woman years, 95% CI: 3.04, 5.31). Women with pregnancies had lower median adherence compared to women without pregnancies (50% [IQR: 45–83] vs. 60% [IQR: 50–100], p = 0.02). Women with pregnancies also had a 48% lower odds of high adherence compared to women without pregnancies when adjusting for confounders (aOR 0.52, 95%CI: 0.41–0.66, p<0.0001). Among women with pregnancies, adherence before and after pregnancy was not different (50% [IQR: 46–83] vs. 55% [IQR: 20–100], p = 0.68).

Conclusions

Women with pregnancies were less likely to have high adherence to study gel compared to women without pregnancies. Understanding these differences may inform findings from HIV prevention trials and future implementation of antiretroviral prophylaxis for at-risk women who choose to conceive. The protocol for the parent trial is registered on ClinicalTrials.gov, NCT00441298, http://www.clinicaltrials.gov/ct2/show/NCT00441298.

HIV PrEP Trials: The Road to Success

The global HIV epidemic cannot be controlled by current treatment or prevention strategies. Pre-exposure prophylaxis (PrEP) using antiretrovirals is a promising approach to curbing the spread of HIV transmission. Recently, four clinical trials demonstrated favorable results when antiretroviral PrEP was administered topically or orally. However, two additional trials were unable to demonstrate a benefit, indicating that further study is required to define the populations and conditions under which PrEP will be effective. Adherence is highly correlated with protection, yet the exact level of adherence required is unknown. Future studies may require increased drug exposure testing and more objective methods to monitor adherence in real-time. Although the development of drug resistance in the PrEP trials has been low, it remains a concern, as therapeutic options could be compromised for those who seroconvert while on PrEP.

Risk for Heterosexual HIV Transmission Among Non-Injecting Female Partners of Injection Drug Users in Estonia

The HIV epidemic in Estonia, as with other eastern European countries, is currently concentrated among injection drug users (IDUs). Non-IDUs who have IDU sex partners could serve as a potential bridge in an expanding epidemic. We applied HIV transmission modelling to data collected from non-IDU/IDU heterosexual couples in Kohtla-Järve, Estonia to estimate HIV risk from IDUs to their sex partners based on self-reported sexual behaviors shared by the couple. IDUs and their current main non-injecting sex partners were recruited for an interviewer-administered survey and HIV testing. Bernoulli modelling techniques were applied to estimate the risk of HIV transmission (incidence) among HIV negative non-injecting female partners of male IDUs. The estimated HIV incidence in this population of non-injecting women with only main sexual partners in the last 6 months ranged from 3.24 to 4.94 HIV seroconversions per 100 person years depending on the value used in the models for the per act transmission rate during acute stage infection. Non-IDUs who have IDU sex partners are at high risk for HIV and could serve as a potential bridge to a more generalized epidemic. Whether this might lead to an expansion of the HIV epidemic beyond core groups in Estonia or other Eastern European countries warrants closer study.

High prevalence of obesity among women who enrolled in HIV prevention trials in KwaZulu-Natal, South Africa: healthy diet and life style messages should be integrated into HIV prevention programs

BACKGROUND

In South Africa, poverty and the dual epidemics of HIV and tuberculosis underscore the need for prevention efforts for obesity. The aim of this study was to describe the prevalence of obesity in a cohort of South African women and discuss the implications for public health practices.

METHODS

A total of 5,495 HIV-negative women from KwaZulu-Natal, South Africa enrolled in three microbicide trials during the period of 2002-2008 were categorised as normal weight (body mass index (BMI: 18.6-<25), overweight (BMI: 25-<30) or obese (BMI: 30+). Incidence of HIV and other sexually transmitted infections such as Chlamydia and gonorrhoea were also estimated and compared by BMI groups. Combined data was analysed using STATA 10.0.

RESULTS

Approximately 70% of the sample population was classified as being overweight or obese. Older age and lack of education were determined to be significant predictors of obesity. Women who were 35 years or older were more than three times as likely to be overweight and more than 12 times as likely to be obese compared to the youngest group. The highest HIV and STI incidence rates were observed among those with BMI <25 kg/m(2) (normal weight) compared to women with BMI more than 25 kg/m2 (8.1 and 19.8 per 100 person-year respectively, P<0.001, both).

CONCLUSION

Effective obesity prevention strategies are needed to re-formulate HIV prevention programmes by incorporating healthy diet and life style messages to target those who are at highest risk not just for HIV infection but also for non-communicable diseases.

Characteristics of female sex workers in southern India willing and unwilling to participate in a placebo gel trial

Respondent-driven sampling was used to recruit female sex workers (FSWs) for a community survey conducted in southern India. After survey completion, participants were given a brochure describing a clinical trial that entailed daily use of a placebo vaginal gel for four months. This study assessed predictors of screening among survey respondents, predictors of enrollment among those eligible for the trial, and predictors of visit attendance and retention among those enrolled. FSWs who reported having symptoms of sexually transmitted infections (STI), engaging in sex work in the past month, and living in a subdistrict easily accessible by public transportation with a high concentration of FSWs, were more likely to screen. FSWs who had never been tested for HIV were more likely to enroll. This analysis suggests that the primary reason FSWs participated in the trial was a desire for health care-not other factors hypothesized to be important, e.g., HIV risk perception and poverty status.

Heterosexual anal intercourse: a neglected risk factor for HIV?

Heterosexual anal intercourse confers a much greater risk of HIV transmission than vaginal intercourse, yet its contribution to heterosexual HIV epidemics has been under-researched. In this article we review the current state of knowledge of heterosexual anal intercourse practice worldwide and identify the information required to assess its role in HIV transmission within heterosexual populations, including input measures required to inform mathematical models. We then discuss the evidence relating anal intercourse and HIV with sexual violence.

Long-term consistent use of a vaginal microbicide gel among HIV-1 sero-discordant couples in a phase III clinical trial (MDP 301) in rural south-west Uganda

BACKGROUND

A safe and effective vaginal microbicide could substantially reduce HIV acquisition for women. Consistent gel use is, however, of great importance to ensure continued protection against HIV infection, even with a safe and effective microbicide. We assessed the long-term correlates of consistent gel use in the MDP 301 clinical trial among HIV-negative women in sero-discordant couples in south-west Uganda.

METHODS

HIV-negative women living with an HIV-infected partner were enrolled between 2005 and 2008, in a three-arm phase III microbicide trial and randomized to 2% PRO2000, 0.5% PRO2000 or placebo gel arms. Follow-up visits continued up to September 2009. The 2% arm was stopped early due to futility and the 229 women enrolled in this arm were excluded from this analysis. Data were analyzed on 544 women on the 0.5% and placebo arms who completed at least 52 weeks of follow-up, sero-converted or became pregnant before 52 weeks. Consistent gel use was defined as satisfying all of the following three conditions: (i) reported gel use at the last sex act for at least 92% of the 26 scheduled visits or at least 92% of the visits attended if fewer than 26; (ii) at least one used applicator returned for each visit for which gel use was reported at the last sex act; (iii) attended at least 13 visits (unless the woman sero-converted or became pregnant during follow-up). Logistic regression models were fitted to investigate factors associated with consistent gel use.

RESULTS

Of the 544 women, 473 (86.9%) were followed for at least 52 weeks, 29 (5.3%) sero-converted and 42 (7.7%) became pregnant before their week 52 visit. Consistent gel use was reported by 67.8%. Women aged 25 to 34 years and those aged 35 years or older were both more than twice as likely to have reported consistently using gel compared to women aged 17 to 24 years. Living in a household with three or more rooms used for sleeping compared to one room was associated with a twofold increase in consistent gel use.

CONCLUSION

In rural Uganda younger women and women in houses with less space are likely to require additional support to achieve consistent microbicide gel use.

TRIAL REGISTRATION

Protocol Number ISRCTN64716212.

Estimating the efficacy of preexposure prophylaxis for HIV prevention among participants with a threshold level of drug concentration

Assays for detecting levels of antiretroviral drugs in study participants are increasingly popular in preexposure prophylaxis (PrEP) trials, since they provide an objective measure of adherence. Current correlation analyses of drug concentration data are prone to bias. In this article, we formulate the causal estimand of prevention efficacy among drug compliers, those who would have had a threshold level of drug concentration had they been assigned to the drug arm of the trial. The identifiability of the causal estimand is facilitated by exploiting the exclusion restriction; that is, drug noncompliers do not acquire any prevention benefit. In addition, we develop an approach to sensitivity analysis that relaxes the exclusion restriction. Applications to published data from 2 PrEP trials, namely the Preexposure Prophylaxis Initiative (iPrEx) trial and the Centre for the AIDS Programme of Research in South Africa (CAPRISA) 004 trial, suggest high efficacy estimates among drug compliers (in the iPrEx trial, odds ratio = 0.097 (95% confidence interval: 0.027, 0.352); in the CAPRISA 004 trial, odds ratio = 0.104 (95% confidence interval: 0.024, 0.447)). In summary, the proposed inferential method provides an unbiased assessment of PrEP efficacy among drug compliers, thus adding to the primary intention-to-treat analysis and correlation analyses of drug concentration data.

Effect of computer-assisted interviewing on self-reported sexual behavior data in a microbicide clinical trial

In a microbicide safety and effectiveness trial (HPTN 035) in Malawi, 585 women completed the same questionnaire through a face-to-face interview (FTFI) and an audio computer-assisted self-interview (ACASI). Concordance between FTFI and ACASI responses ranged from 72.0 % for frequency of sex in the past week to 95.2 % for anal intercourse (AI) in the past 3 months. Reported gel and condom use at last sex act were marginally lower with ACASI than FTFI (73.5 % vs. 77.2 %, p = 0.11 and 60.9 % vs. 65.5 %, p = 0.05, respectively). More women reported AI with ACASI than FTFI (5.0 % vs. 0.2 %, p < 0.001). Analyses of consistency of responses within ACASI revealed that 15.0 % of participants in the condom-only arm and 28.7 % in the gel arm provided at least one discrepant answer regarding total sex acts and sex acts where condom and gel were used (19.2 % reported one inconsistent answer, 8.1 % reported two inconsistent answers, and 1.4 % reported three inconsistent answers). While ACASI may provide more accurate assessments of sensitive behaviors in HIV prevention trials, it also results in a high level of internally inconsistent responses.

State of the science of adherence in pre-exposure prophylaxis and microbicide trials

For pre-exposure prophylaxis (PrEP) and microbicides to effectively prevent HIV, optimal treatment adherence is required. Adherence to these strategies, however, has not been sufficiently studied. This investigation systematically reviews oral PrEP and microbicide trials across 4 domains of adherence: (1) definition and measures used, (2) risks for nonadherence, (3) promotion strategies, and (4) effects on outcomes. Nineteen (n = 19) trials, with 47,157 participants, published between 1987 and 2012 were identified. Reported mean adherence to microbicides was 79% and to oral PrEP 87%. Common risks for microbicide nonadherence were decreased motivation over time, sex with primary (noncommercial/casual) partners, and insufficient supply. Oral PrEP nonadherence risks were older age and medication side effects. Psychoeducation and outreach to participants and communities were frequently used promotion strategies. Most trials failed to systematically identify barriers and monitor and promote adherence, although adherence moderated outcomes. Recommendations for attending to adherence in future trials are provided.

Homeostatic properties of Lactobacillus jensenii engineered as a live vaginal anti-HIV microbicide

Background

Vaginal probiotics are investigated as a binary strategy for prevention of bacterial vaginosis and HIV. We applied an innovative experimental model using primary and immortalized human cervical and vaginal epithelial cells to assess the functional properties of Lactobacillus jensenii, a predominant constituent of the healthy vaginal microbiome, engineered to express the HIV-1 entry inhibitor modified cyanovirin-N (mCV-N). In this model bacteria colonize the epithelial cells over a period of 24-72 h. Staurosporine and the Toll-like receptor 2/6 ligand macrophage-activating lipopeptide-2 (MALP-2) serve as positive controls for apoptosis and proinflammatory activation, respectively. In 24-hour intervals, the colonized epithelium is assessed microscopically, supernatants are collected for measurement of soluble immunoinflammatory mediators and production of CV-N, and cells are lysed for assessment of: 1) apoptosis by cleaved versus total caspase-3 assay; 2) NF-κB activation by a luciferase reporter assay; or 3) epithelia-associated colony forming units (CFU) in Brucella agar.

Results

Wild type (WT) L. jensenii 1153 consistently colonized cervical and vaginal cells in the absence of epithelial damage and apoptosis. The bioengineered derivatives expressing mCV-N or control plasmids showed the same stable colonization pattern, which was reproducible between technologists and bacterial batches (CFU coefficient of variation <10% within and between experiments and epithelial cell types). MALP-2 activated NF-κB and caused fold-increased levels of proinflammatory mediators with clinically established significance in the cervicovaginal environment (IL-1α, IL-1β, IL-6, TNF-α, IL-8, RANTES, MIP-3α, and ICAM-1), measured by a multiplex electrochemiluminescence assay. At the same time levels of protective anti-inflammatory mediators interleukin 1 receptor antagonist (IL-1RA) and secretory leukocyte protease inhibitor (SLPI), both measured by ELISA, remained constant (IL-1RA) or moderately increased (SLPI). Similarly to MALP-2, colonization by L. jensenii WT activated NF-κB; however, unlike the synthetic TLR2/6 ligand, the live microorganisms did not induce significant changes in the secreted levels across all inflammation-associated proteins. The mCV-N production and function were confirmed by western blot and a HIV-1 gp120 binding assay, respectively. The bioengineered lactobacilli expressed mCV-N with anti-HIV activity preserved in the epithelial cell context and caused no significant immunoinflammatory changes as compared to the WT L. jensenii.

Conclusions

These results highlight the translational value of the colonization model and justify further clinical investigation of the homeostatic and anti-HIV effectiveness of the L. jensenii derivates.

Microbicide dosage forms

Microbicides are topically applied, user controlled dosage forms that are being developed to prevent the transmission of HIV during coitus. Early candidates focused on coitally dependent dosage forms such as gels and creams. More recent development has focused on broadening the coitally dependent options through the introduction of films and fast dissolving tablets. Additionally, it has become important to have longer acting products to minimize the burden of user compliance and thus vaginal rings have been developed providing sustained delivery of antiretroviral drugs. This chapter discusses the history of microbicides along with a detailed description of coitally dependent products, gels, films, tablets diaphragms, as well as coitally independent dosage forms such as vaginal rings and the introduction of a new technology, electrospun fibers.