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

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.

Microbicides for prevention of HIV infection: clinical efficacy trials

Microbicides are an important HIV prevention technology under development, but the clinical testing of candidate products for efficacy faces many design and ethical challenges. Nevertheless, several microbicide candidates have been tested or are under development. Eight candidate products have entered late stage microbicide effectiveness trials. Following 11 disappointing effectiveness trial results of six candidate products over the past 20 years, substantial progress is now being made in microbicide development following the release of the CAPRISA 004 tenofovir gel trial results in 2010, which provided proof of concept that topical antiretroviral microbicides can prevent sexual transmission of HIV and herpes simplex type-2 infection. A trial is currently underway to confirm the effectiveness of tenofovir gel and two others have recently been initiated to assess ring formulations of the antiretroviral drug, dapivirine.

Trypan blue staining to determine vaginal exposure in two types of plastic vaginal applicators containing two different microbicide formulations

Dye staining of applicators has been shown to be a reliable and objective method to test vaginal insertion in clinical microbicide trials, but different plastics, dyes, and product formulations may impact the accuracy of this method. Reportedly used applicators returned from 3 clinical trials were stained with 1% trypan blue. In a phase 1 study (VivaGel), using gel-filled HTI polypropylene applicators, 1271 (97%) of applicators stained positive. In a phase 1 and a phase 2a study (LACTIN-V) using linear low-density polyethylene applicators to deliver a dry powder formulation, 57 (95%) and 135 (86%) tested positive, respectively. Dye staining of vaginal applicators is an objective low-cost measure suitable for low-resource settings.

Carraguard acceptability among men and women in a couples study in Thailand

OBJECTIVE

The aim of this study is to evaluate the use and acceptability of Carraguard among men and women enrolled as couples in a microbicide trial.

MATERIALS AND METHODS

Focus groups were conducted with participants in a 6-month randomized, placebo-controlled trial that enrolled sexually active, low-risk couples in Thailand. Participants were blinded as to which gel they had received at the time of the discussions.

RESULTS

Most men and women liked the gel and found it acceptable. The majority of men and women thought that using the gel increased sexual pleasure, although participants disagreed about whether using the gel increased sexual frequency. Drawbacks of gel use included that it was too wet or messy, and nearly all respondents thought that the applicator was too hard. Most men and women questioned the utility of using the gel among married couples since gel use was tied to perception of HIV/STI risk. However, those who perceived themselves to be at risk expressed interest in using the product as an alternative to condoms. Many women were particularly interested in a product that also had contraceptive properties. Gel use also raised issues of trust and fidelity among couples and questions about men's ability to detect women's use of the product.

CONCLUSION

Men and women in this study found the gel acceptable and thought that it should be made available if it is found to be safe and effective. Strategies for marketing a potential microbicide product must take the target population into consideration. For married couples, key considerations may be partner dynamics and trust issues, whereas messages focusing on sexual pleasure or disease prevention may resonate more strongly with sex workers or other populations.

TSPY4 is a novel sperm-specific biomarker of semen exposure in human cervicovaginal fluids; potential use in HIV prevention and contraception studies

BACKGROUND

Developing an objective, reliable method to determine semen exposure in cervicovaginal fluids is important for accurately studying the efficacy of vaginal microbicides and contraceptives. Y-chromosome biomarkers offer better stability, sensitivity, and specificity than protein biomarkers. TSPY4 belongs to the TSPY (testis-specific protein Y-encoded) family of homologous genes on the Y-chromosome. Using a multiplex PCR amplifying TSPY4, amelogenin, and Sex-determining region in the Y chromosome (SRY), our objective was to determine whether a gene in the TSPY family was a more sensitive marker of semen exposure in cervicovaginal fluids than SRY.

STUDY DESIGN

The multiplex polymerase chain reaction (PCR) was developed using sperm and vaginal epithelial (female) DNA. Diluted sperm DNA and mixed male/female DNA was used to determine the sensitivity of the multiplex PCR. Potential interference of TSPY4 amplification by components in cervicovaginal and seminal fluids was determined. TSPY4 and SRY amplification was also investigated in women participating in a separate IRB-approved clinical study in which cervicovaginal swab DNA was collected before semen exposure and at various time points after exposure.

RESULTS

TSPY4, SRY, and amelogenin were amplified in sperm DNA, but only amelogenin in female DNA. The limit of sperm DNA from which TSPY4 could be amplified was lower than SRY (4 pg vs 80 pg). TSPY4 could also be amplified from mixed male/female DNA. Amplification was not affected by cervicovaginal and seminal components. Using cervicovaginal swab DNA from three women before and after semen exposure, TSPY4 was detected up to 72 h post exposure while SRY detection was observed up to 24-48 h. TSPY4 was detected up to 7 days post exposure in one out of three women.

CONCLUSIONS

We have demonstrated that TSPY4 is a new sensitive, and sperm-specific biomarker. The multiplex PCR incorporating this new biomarker has potential to be an objective measure for determining semen exposure in clinical trials of vaginal products such as contraceptives and HIV pre/post-exposure prophylaxis agents.

Development and evaluation of a thermosensitive vaginal gel containing raltegravir+efavirenz loaded nanoparticles for HIV prophylaxis

The objective of this investigation was to develop a thermosensitive vaginal gel containing raltegravir+efavirenz loaded PLGA nanoparticles (RAL+EFV-NPs) for pre-exposure prophylaxis of HIV. RAL+EFV-NPs were fabricated using a modified emulsion-solvent evaporation method and characterized for size and zeta potential. The average size and surface charge of RAL+EFV-NP were 81.8±6.4 nm and -23.18±7.18 mV respectively. The average encapsulation efficiency of raltegravir and efavirenz was 55.5% and 98.2% respectively. Thermosensitive vaginal gel containing RAL+EFV-NPs was successfully prepared using a combination of Pluronic F127 (20% w/v) and Pluronic F68 (1% w/v). Incorporation RAL+EFV-NPs in the gel did not result in nanoparticle aggregation and RAL+EFV-NPs containing gel showed thermogelation at 32.5°C. The RAL+EFV-NPs were evaluated for inhibition of HIV-1(NL4-3) using TZM-bl indicator cells. The EC(90) of RAL+EFV-NPs was lower than raltegravir+efavirenz (RAL+EFV) solution but did not reach significance. Compared to control HeLa cells without any treatment, RAL+EFV-NPs or blank gel were not cytotoxic for 14 days in vitro. The intracellular levels of efavirenz in RAL+EFV-NPs treated HeLa cells were above the EC(90) for 14 days whereas raltegravir intracellular concentrations were eliminated within 6 days. Transwell experiments of NPs-in-gel demonstrated rapid transfer of fluorescent nanoparticles from the gel and uptake in HeLa cells within 30 min. These data demonstrate the potential of antiretroviral NP-embedded vagina gels for long-term vaginal pre-exposure prophylaxis of heterosexual HIV-1 transmission.

Vaginal microbicides for reducing the risk of sexual acquisition of HIV infection in women: systematic review and meta-analysis

BACKGROUND

Each year more than two million people are newly infected with HIV worldwide, a majority of them through unprotected vaginal sex. More than half of new infections in adults occur in women. Male condoms and male circumcision reduce the risk of HIV acquisition; but the uptake of these methods is out of the control of women. We therefore aimed to determine the effectiveness of vaginal microbicides (a potential female-controlled method) for prevention of sexual acquisition of HIV in women.

METHODS

We conducted a comprehensive search of peer-reviewed and grey literature for publications of randomised controlled trials available by September 2012. We screened search outputs, selected studies, assessed risk of bias, and extracted data in duplicate; resolving differences by discussion and consensus.

RESULTS

We identified 13 eligible trials that compared vaginal microbicides to placebo. These studies enrolled 35,905 sexually active HIV-negative women between 1996 and 2011; in Benin, Cameroon, Cote d'Ivoire, Ghana, Kenya, Malawi, Nigeria, South Africa, Tanzania, Uganda, Zambia, Zimbabwe, India, Thailand, and the United States of America. A small trial of 889 women found that tenofovir (a nucleotide reverse transcriptase inhibitor) significantly reduces the risk of HIV acquisition (risk ratio [RR] 0.63, 95% confidence intervals [CI] 0.43 to 0.93). Effectiveness data are not yet available from follow-up tenofovir trials being conducted in South Africa, Uganda, and Zimbabwe (1 trial) and multiple sites in South Africa (1 trial). We found no evidence of a significant effect for nonoxynol-9 (5 trials), cellulose sulphate (2 trials), SAVVY (2 trials), Carraguard (1 trial), PRO 2000 (2 trials), and BufferGel (1 trial) microbicides. The pooled RR for the effect of current experimental vaginal microbicides on HIV acquisition in women was 0.97, 95%CI 0.87 to 1.08. Although study results were homogeneous across the different drug classes (heterogeneity P = 0.17, I2 = 27%), the overall intervention effect was not statistically significant. Nonoxynol-9 significantly increased the risk of having adverse genital lesions but no other microbicide led to significant increases in adverse events.

CONCLUSIONS

There is not enough evidence at present to recommend vaginal microbicides for HIV prevention. Further high-quality research is needed to confirm the beneficial effects of tenofovir as well as continue the development and testing of new microbicides.

The clinical pharmacology of antiretrovirals for HIV prevention

PURPOSE OF REVIEW

Pre-exposure prophylaxis (PrEP) clinical trial results using antiretrovirals can seem confusing, if not conflicting. We review recent antiretroviral pharmacokinetic studies to help explain PrEP trial results.

RECENT FINDINGS

Pharmacokinetic studies indicate that topical dosing, compared with oral dosing, achieves far higher colon and vaginal tissue drug concentrations, and far lower drug concentrations in blood. After oral dosing, higher tenofovir diphosphate concentrations are found in colon tissue than cervico-vaginal tissue, but the reverse is the case for emtricitabine triphosphate, although it does not persist as long. Vaginal dosing achieves measurable tenofovir concentrations in the rectum and vice versa. Within and among oral PrEP trials, increased drug concentration is associated with increased HIV protection, with drug concentration differences best explained by adherence, rather than pharmacokinetics. The poor level of protection in topical studies is not consistent with concentration-response in oral studies indicating unknown variables in need of further investigation.

SUMMARY

Sparse pharmacokinetic sampling in large trials combined with more intensive sampling in smaller pharmacokinetic-focused studies help explain trial outcome differences due largely to differences in adherence, tissue pharmacokinetics, and type of HIV exposure. Pharmacokinetic analysis can identify protective drug concentration targets, guide dose optimization, and inform future trials.

The nonnucleoside reverse transcription inhibitor MIV-160 delivered from an intravaginal ring, but not from a carrageenan gel, protects against simian/human immunodeficiency virus-RT Infection

We previously showed that a carrageenan (CG) gel containing 50 μM MIV-150 (MIV-150/CG) reduced vaginal simian/human immunodeficiency virus (SHIV)-RT infection of macaques (56%, p>0.05) when administered daily for 2 weeks with the last dose given 8 h before challenge. Additionally, when 100 mg of MIV-150 was loaded into an intravaginal ring (IVR) inserted 24 h before challenge and removed 2 weeks after challenge, >80% protection was observed (p<0.03). MIV-160 is a related NNRTI with a similar IC(50), greater aqueous solubility, and a shorter synthesis. To objectively compare MIV-160 with MIV-150, herein we evaluated the antiviral effects of unformulated MIV-160 in vitro as well as the in vivo protection afforded by MIV-160 delivered in CG (MIV-160/CG gel) and in an IVR under regimens used with MIV-150 in earlier studies. Like MIV-150, MIV-160 exhibited potent antiviral activity against SHIV-RT in macaque vaginal explants. However, formulated MIV-160 exhibited divergent effects in vivo. The MIV-160/CG gel offered no protection compared to CG alone, whereas the MIV-160 IVRs protected significantly. Importantly, the results of in vitro release studies of the MIV-160/CG gel and the MIV-160 IVR suggested that in vivo efficacy paralleled the amount of MIV-160 released in vitro. Hundreds of micrograms of MIV-160 were released daily from IVRs while undetectable amounts of MIV-160 were released from the CG gel. Our findings highlight the importance of testing different modalities of microbicide delivery to identify the optimal formulation for efficacy in vivo.

A single dose of a MIV-150/Zinc acetate gel provides 24 h of protection against vaginal simian human immunodeficiency virus reverse transcriptase infection, with more limited protection rectally 8-24 h after gel use

Previously we showed that repeated vaginal application of a MIV-150/zinc acetate carrageenan (MIV-150/ZA/CG) gel and a zinc acetate carrageenan (ZA/CG) gel significantly protected macaques from vaginal simian human immunodeficiency virus reverse transcriptase (SHIV-RT) infection. Gels were applied either daily for 2 weeks or every other day for 4 weeks, and the animals were challenged 4-24 h later. Herein, we examined the effects of a single vaginal dose administered either before or after virus challenge. Encouraged by the vaginal protection seen with MIV-150/ZA/CG, we also tested it rectally. Vaginal applications of MIV-150/ZA/CG, ZA/CG, and CG gel were performed once 8-24 h before, 1 h after, or 24 h before and 1 h after vaginal challenge. Rectal applications of MIV-150/ZA/CG and CG gel were performed once 8 or 24 h before rectal challenge. While vaginal pre-challenge and pre/post-challenge application of MIV-150/ZA/CG gel offered significant protection (88%, p<0.002), post-challenge application alone did not significantly protect. ZA/CG gel reduced infection prechallenge, but not significantly, and the effect was completely lost post-challenge. Rectal application of MIV-150/ZA/CG gel afforded limited protection against rectal challenge when applied 8-24 h before challenge. Thus, MIV-150/ZA/CG gel is a highly effective vaginal microbicide that demonstrates 24 h of protection from vaginal infection and may demonstrate efficacy against rectal infection when given close to the time of HIV exposure.

Understanding factors that modulate HIV infection at the female genital tract mucosae for the rationale design of microbicides

Women are now becoming the pivot of the epidemiological spread of HIV infection worldwide, especially in developing countries. Therefore, research to develop an efficient microbicide is now a priority for the prevention of HIV-1 acquisition in exposed women. However, recent disappointing failures in microbicide clinical trials revealed major gaps in basic and applied knowledge that hinder the development of effective microbicide formulations. Indeed, the inhibitory power of microbicide molecules may be affected by several physiological and immunological factors present in male and female genital tracts. Furthermore, mucosal crossing of HIV-1 to increase the ability to reach the submucosal target cells (macrophages, lymphocytes, and dendritic cells) may be modulated by supraepithelial factors such as seminal complement components (opsonized HIV-1), by epithelial factors released in the submucosal microenvironment such as antimicrobial soluble factors, cytokines, and chemokines, and by potent intraepithelial and submucosal innate immunity. The design of vaginal microbicide formulations should take into account an understanding of the intimate mechanisms involved in the crossing of HIV through the female genital mucosae, in the context of a mixture of both male and female genital fluids.

Premature activation of the HIV RNase H drives the virus into suicide: a novel microbicide?

Sexual transmission of HIV is the major cause of spread of HIV in Africa and the Third World and is an unmet medical need. Recently, microbicides have attracted attention because they allow females to protect themselves and their offspring. We are exploiting one of the four retroviral enzymes, the ribonuclease H, RNase H, as a novel approach for a microbicide. It is the only enzyme of HIV not yet targeted by antiretroviral therapy. The enzyme is linked to the reverse transcriptase (RT) and hydrolyzes the RNA moiety of RNA-DNA hybrids. The RNase H is located inside virus particles and normally functions during viral replication inside cells. Here we show that activating the RNase H prematurely inside the virus particles destroys the viral genome and abrogates viral infectivity. The antiviral compound consists of a synthetic oligodeoxynucleotide (ODN), which creates an artificial RNA-DNA hybrid substrate for the RNase H inside the particle. The compound was analyzed in mouse models including humanized SCID mice and the vagina of mice. Infection was reduced up to 1000-fold or could be completely prevented. The compound is suitable as microbicide or to prevent mother-to-child transmission.

The Promise of Antiretrovirals for HIV Prevention

With an estimated 2.6 million new HIV infections diagnosed annually, the world needs new prevention strategies to partner with condom use, harm reduction approaches for injection drug users, and male circumcision. Antiretrovirals can reduce the risk of mother-to-child HIV transmission and limit HIV acquisition after occupational exposure. Macaque models and clinical trials demonstrate efficacy of oral or topical antiretrovirals used prior to HIV exposure to prevent HIV transmission, ie pre-exposure prophylaxis (PrEP). Early initiation of effective HIV treatment in serodiscordant couples results in a 96% decrease in HIV transmission. HIV testing to determine serostatus and identify undiagnosed persons is foundational to these approaches. The relative efficacy of different approaches, adherence, cost and long-term safety will affect uptake and impact of these strategies. Ongoing research will help characterize the role for oral and topical formulations and help quantify potential benefits in sub-populations at risk for HIV acquisition.

Predicting product adherence in a topical microbicide safety trial in Pune, India

The inconclusive results of past trials and recent findings of partial protection of Tenofovir 1% gel underscore the need to better understand product adherence in microbicide trials. This study aimed to identify factors predicting couples' ability to sustain topical gel and condom use during clinical trial participation. We enrolled 100 Indian participants of a randomized, controlled safety trial of Tenofovir 1% gel (CT cohort) and 100 similar women who were ineligible or declined trial participation (NCT cohort). Compared to the NCT cohort, CT women reported higher baseline condom use, more positive attitudes towards condoms and higher levels of protection efficacy. While NCT condom use remained low, CT condom use increased dramatically during the study. Reported gel consistency was higher than condom consistency. Individual and couple-related factors predicted condom consistency and interest in future gel use, but not gel consistency. Findings could inform trial recruitment strategies and product introduction.

HIV incidence among non-pregnant women living in selected rural, semi-rural and urban areas in KwaZulu-Natal, South Africa

The province of KwaZulu-Natal has the highest prevalence of HIV in South Africa, particularly among young women. In order to more closely examine the HIV prevalence and incidence in non-pregnant women from rural, semi-rural and urban areas, data from 5,753 women screened for enrolment into three HIV prevention studies were combined and analysed. The prevalence of HIV infection was 43% at screening. HIV incidence among the 2,523 enrolled HIV-negative women was determined every quarter, and sexual behaviour and socio-demographic data were collected as per respective protocols. During follow-up, 211 women seroconverted (6.6/100 women years). Multivariate analysis found that seroconversion rates were highest among women who were ≤24 years old, single and not cohabiting, and who had incident sexually transmitted infections. The epidemic in KwaZulu-Natal calls for targeted HIV prevention interventions among those at highest risk of acquiring or transmitting infection.

Willingness of clinicians to integrate microbicides into HIV prevention practices in southern Africa

The first vaginal microbicide was recently proven effective in clinical trials. We assessed the willingness of clinicians to integrate microbicides into HIV prevention practices in Southern Africa, where women face elevated HIV risks. We conducted in-depth interviews (n = 60) and nationally representative surveys (n = 1,444) in South Africa and Zimbabwe with nurses and physicians. Over half of clinicians (58%) were aware of microbicides, with physicians far more likely than nurses to be familiar. Clinicians, including those in rural areas, were generally willing to discuss microbicides, a female-initiated method less effective than the condom, particularly when condom use was unlikely (70%). Fewer would include microbicides while counseling adolescents (51%). Most clinicians (85%) thought their patients would use microbicides; greater clinician familiarity with microbicides was significant for support. Training for both nurses and physicians prior to introduction is critical, so they have sufficient knowledge and skills to offer a microbicide upon availability.

Prevention of sexually transmitted HIV infections through the President's Emergency Plan for AIDS Relief: a history of achievements and lessons learned

HIV prevention in the President's Emergency Plan for AIDS Relief (PEPFAR) began when both data on HIV prevalence and the toolbox of interventions for prevention of sexual transmission were relatively limited. PEPFAR's early focus was on scaling-up information, education, and communication programs that included messaging on abstinence for youth and faithfulness primarily through nongovernmental organizations, including faith-based organizations. Additional activities included condom promotion, distribution, and social marketing. In epidemics concentrated within key populations, PEPFAR's prevention efforts focused on a minimum package of services including outreach, information, education, and communication programs, STI treatment (where appropriate), and condom promotion and distribution. As more epidemiological data became available and with experience gleaned in these early efforts, the need for tailored and flexible approaches became evident. The next iteration of prevention efforts still emphasized behavioral interventions, but incorporated a sharper focus on key epidemic drivers, especially multiple partners; a data-driven emphasis on high transmission areas and populations, including prevention with people living with HIV; and a more strategic and coordinated approach at the national level. Recently, the paradigm for prevention efforts has shifted yet again. Evidence that biomedical interventions such as male circumcision, treatment for prevention of vertical and horizontal transmission, and treatment itself could lead to declines in incidence has refocused PEPFAR's prevention portfolio. New guidance on sexually transmitted HIV focuses on combination prevention, emphasizing biomedical, behavioral and structural approaches. Landmark speeches by the President and the Secretary of State and new ambitious targets for PEPFAR point toward a new goal: an AIDS-free generation.

'It looks like you just want them when things get rough': civil society perspectives on negative trial results and stakeholder engagement in HIV prevention trials

Civil society organizations (CSOs) have significantly impacted on the politics of health research and the field of bioethics. In the global HIV epidemic, CSOs have served a pivotal stakeholder role. The dire need for development of new prevention technologies has raised critical challenges for the ethical engagement of community stakeholders in HIV research. This study explored the perspectives of CSO representatives involved in HIV prevention trials (HPTs) on the impact of premature trial closures on stakeholder engagement. Fourteen respondents from South African and international CSOs representing activist and advocacy groups, community mobilisation initiatives, and human and legal rights groups were purposively sampled based on involvement in HPTs. Interviews were conducted from February-May 2010. Descriptive analysis was undertaken across interviews and key themes were developed inductively. CSO representatives largely described positive outcomes of recent microbicide and HIV vaccine trial terminations, particularly in South Africa, which they attributed to improvements in stakeholder engagement. Ongoing challenges to community engagement included the need for principled justifications for selective stakeholder engagement at strategic time-points, as well as the need for legitimate alternatives to CABs as mechanisms for engagement. Key issues for CSOs in relation to research were also raised.

The safety, persistence, and acceptability of an antiretroviral microbicide candidate UC781

OBJECTIVE

: To evaluate the persistence and acceptability of a minimally absorbed vaginal gel antiretroviral designed to block the acquisition of HIV.

METHODS

: Sixty healthy women aged 18-45 participated in a phase-1 randomized placebo-controlled trial of a vaginal gel containing the nonnucleoside reverse transcriptase inhibitor UC781. Women underwent a single timed exposure ranging from 0 to 8 hours and were followed for 35 days. Safety was assessed by symptoms, physical exam, laboratory evaluation, and colposcopy. Persistence was assessed by drug levels in cervicovaginal lavage (CVL) and vaginal swab specimens.

RESULTS

: The participants' mean age was 26 years; 77% were white. The most frequently reported adverse events were genitourinary; however, the placebo and UC781 arms had a similar distribution of mild and moderate genitourinary events. All colposcopic findings were superficial. Measuring systemic UC781 levels in the plasma revealed that 2 (5%) women in the UC781 gel group had detectable UC781; however, the amount was below the limits of quantification (2.5 ng/mL) in both participants. UC781 was detected in 37 of 40 CVL samples obtained 1-2 days after drug exposure and initial CVL; the median level of UC781 was 4965 pmol/mL, significantly higher than the known IC50 of 10 pmol/mL. Eighty percent of participants reported that they would use the product if it were found to be protective against HIV.

CONCLUSION

: In this population of HIV-uninfected women, the gel was well tolerated and acceptable. Active levels of drug were detected in CVL and vaginal swab specimens at 1-2 days at concentrations supporting the role for daily dosing.

How effective is effective enough? Opinions of potential end-users of microbicides from a rural South African community

To assess the views of potential end-users of a microbicide in KwaZulu-Natal regarding the characteristics that would justify further development, three focus group discussions were conducted in 2009 with 23 local staff members working on a microbicide clinical trial, 20 former trial participants and 14 Community Advisory Board members not enrolled in the trial, in an area with high HIV incidence and low consistent condom use. All participants agreed on the need for additional HIV prevention options that are as effective as possible and can be used by women. The majority of respondents stated that even a highly acceptable HIV prevention option with protection as low as 30% would still be an important addition to condoms for women; that a partially protective microbicide would have to be introduced as part of the existing prevention messages in order to continue promoting condom use; that there should eventually be a choice between antiretroviral (ARV) and non-ARV-based microbicides and a choice of how and where to access microbicides. Respondents also felt it would be important to make plans for access to a microbicide that can offer protection, even if partial, rather than wait to find out if alternative microbicides are equally or more effective. Potential end-users in a high HIV prevalence area believe that a partially effective microbicide would be an important addition to the limited HIV prevention options for women. The significant challenges of introducing a partially protective HIV prevention option were recognised, but seen as ones worth facing, as well as an opportunity to lay the ground work for the introduction of more efficacious HIV prevention methods in the future.

Mucosal Escherichia coli bactericidal activity and immune mediators are associated with HIV-1 seroconversion in women participating in the HPTN 035 trial

The mucosal environment may impact the risk for human immunodeficiency virus type 1 (HIV-1) acquisition. Immune mediators were measured in vaginal fluid collected from HPTN 035 participants who acquired HIV-1 and from those who remained HIV-1 negative (controls). Mediator concentrations were similar in samples obtained before as compared to after HIV-1 acquisition in the 8 seroconverters. Compared with controls, seroconverters were more likely to have detectable levels of HβD-2 (odds ratio [OR], 2.39; P = .005) and greater Escherichia coli bactericidal activity (OR, 1.22; P = .01) prior to seroconversion. E. coli bactericidal activity remained significant in a multivariable analysis (P = .02) and may be a biomarker for HIV-1 acquisition.

An intravaginal ring that releases the NNRTI MIV-150 reduces SHIV transmission in macaques

Microbicides may prevent HIV and sexually transmitted infections (STIs) in women; however, determining the optimal means of delivery of active pharmaceutical ingredients remains a major challenge. We previously demonstrated that a vaginal gel containing the non-nucleoside reverse transcriptase inhibitor MIV-150 partially protected macaques from SHIV-RT (simian/HIV reverse transcriptase) infection, and the addition of zinc acetate rendered the gel significantly protective. We test the activity of MIV-150 without the addition of zinc acetate when delivered from either ethylene vinyl acetate (EVA) or silicone intravaginal rings (IVRs). MIV-150 was successfully delivered, because it was detected in vaginal fluids and tissues by radioimmunoassay in pharmacokinetic studies. Moreover, EVA IVRs significantly protected macaques from SHIV-RT infection. Our results demonstrate that MIV-150-containing IVRs have the potential to prevent HIV infection and highlight the possible use of IVRs for delivering drugs that block HIV and other STIs.

Lessons learned from a double-blind randomised placebo-controlled study with a iota-carrageenan nasal spray as medical device in children with acute symptoms of common cold

Background

Common cold is caused by a variety of respiratory viruses. The prevalence in children is high, and it potentially contributes to significant morbidity. Iota-carragenan, a polymer derived from red seaweed, has reduced viral load in nasal secretions and alleviated symptoms in adults with common cold.

Methods

We have assessed the antiviral and therapeutic activity of a nasal spray containing iota-carrageenan in children with acute symptoms of common cold. A cohort of 153 children between 1–18 years (mean age 5 years), displaying acute symptoms of common cold were randomly assigned to treatment with a nasal spray containing iota-carrageenan (0.12%) as verum or 0.9% sodium chloride solution as placebo for seven days. Symptoms of common cold were recorded and the viral load of respiratory viruses in nasal secretions was determined at two consecutive visits.

Results

The results of the present study showed no significant difference between the iota carrageenan and the placebo group on the mean of TSS between study days 2–7. Secondary endpoints, such as reduced time to clearance of disease (7.6 vs 9.4 days; p = 0.038), reduction of viral load (p = 0.026), and lower incidence of secondary infections with other respiratory viruses (p = 0.046) indicated beneficial effects of iota-carrageenan in this population. The treatment was safe and well tolerated, with less side effects observed in the verum group compared to placebo.

Conclusion

In this study iota-carrageenan did not alleviate symptoms in children with acute symptoms of common cold, but significantly reduced viral load in nasal secretions that may have important implications for future studies.

Trial registration

ISRCTN52519535, http://www.controlled-trials.com/ISRCTN52519535/

The meaning of adherence when behavioral risk patterns vary: obscured use- and method-effectiveness in HIV-prevention trials

BACKGROUND

Recently promising trials of innovative biomedical approaches to prevent HIV transmission have been reported. Participants' non-adherence to the prevention methods complicates the analyses and interpretation of trial results. The influence of variable sexual behaviors within and between participants of trials further obscures matters. Current methodological and statistical approaches in HIV-prevention studies, as well as ongoing debates on contradictory trial results, may fail to accurately address these topics.

METHODOLOGY/PRINCIPAL FINDINGS

Through developing a cumulative probability model of infection within HIV prevention trials, we demonstrate how adherence and sexual behavior patterns impact the overall estimate of effectiveness, the effectiveness of prevention methods as a function of adherence, and conclusions about methods' true effectiveness. Applying the model to summary-level data from the CAPRISA trial, we observe markedly different values for the true method effectiveness of the microbicide, and show that if the gel would have been tested among women with slightly different sexual behavior patterns, conclusions might well have been that the gel is not effective.

CONCLUSIONS/SIGNIFICANCE

Relative risk and adherence analyses in HIV prevention trials overlook the complex interplay between adherence and sexual behavior patterns. Consequently, they may not provide accurate estimates of use- and method-effectiveness. Moreover, trial conclusions are contingent upon the predominant sexual behavior pattern of participants and cannot be directly generalized to other contexts. We recommend researchers to (re)examine their data and use the cumulative probability model to estimate the true method effectiveness, which might contribute to resolving current questions about contradictory trial results. Moreover, we suggest taking into account the issues raised in the design of future trials and in population models estimating the impact of large-scale dissemination of prevention methods. Comprehension of the topics described will help readers to better interpret (apparently contradictory) trial outcomes.

Controlled-release vaginal ring drug-delivery systems: a key strategy for the development of effective HIV microbicides

BACKGROUND

Over half of all HIV-infected adults are women and heterosexual intercourse is a significant mode of viral transmission. This review examines the potential for using polymeric vaginal ring systems to provide controlled delivery of HIV microbicides in order to prevent heterosexual transmission of the virus.

DISCUSSION

Continuous delivery of microbicides has the potential to be more effective than one-off dosing. Thus, controlled-release vaginal delivery devices are now a key area of HIV prevention research. Initial clinical trials on vaginal rings loaded with dapivirine (a candidate microbicide) have indicated that these products are safe and well tolerated by women. These devices are female-initiated, robust and capable of long-term delivery of the active agent.

CONCLUSIONS

Vaginal rings may offer an effective system for the controlled delivery of microbicides to prevent heterosexual transmission of HIV. Candidate vaginal ring microbicide products are now in clinical trials.

The importance of the vaginal delivery route for antiretrovirals in HIV prevention

The HIV/AIDS pandemic continues to be a global health priority, with high rates of new HIV-I infections persisting in young women. One HIV prevention strategy is topical pre-exposure prophylactics or microbicides, which are applied vaginally or rectally to protect the user from HIV and possibly other sexually transmitted infections. Vaginal microbicide delivery will be the focus of this review. Multiple nonspecific and specific antiretroviral microbicide products have been clinically evaluated, and many are in preclinical development, The events of HIV mucosal transmission and dynamics of the cervicovaginal environment should be considered for successful vaginal microbicide delivery. Beyond conventional vaginal formulations, intravaginal rings, tablets and films are employed as platforms in the hope to increase the likelihood of microbicide use. Furthermore, combining multiple antiretrovirals within a given formulation, combining a microbicide product with a vaginal device and integrating novel drug-delivery strategies within a microbicide product are approaches to successful vaginal-microbicide delivery.

Controlling the HIV/AIDS epidemic: current status and global challenges

This review provides an overview of the current status of the global HIV pandemic and strategies to bring it under control. It updates numerous preventive approaches including behavioral interventions, male circumcision (MC), pre- and post-exposure prophylaxis (PREP and PEP), vaccines, and microbicides. The manuscript summarizes current anti-retroviral treatment options, their impact in the western world, and difficulties faced by emerging and resource-limited nations in providing and maintaining appropriate treatment regimens. Current clinical and pre-clinical approaches toward a cure for HIV are described, including new drug compounds that target viral reservoirs and gene therapy approaches aimed at altering susceptibility to HIV infection. Recent progress in vaccine development is summarized, including novel approaches and new discoveries.

Contraception and pregnancy in microbicide trials

The distinctive feature of the human immunodeficiency virus (HIV) epidemic in Sub-Saharan Africa is the burden on women, in particular young women of reproductive age. Consequently, most late-phase effectiveness microbicide clinical trials are conducted in sub-Saharan Africa where fertility rates are high. Because late-phase clinical trials are conducted over prolonged periods of time, women participating in these trials may fall pregnant during the trial. Their unborn babies may be exposed to a drug whose teratogenic potential is unknown if the investigational drug is not withdrawn. High pregnancy rates in such trials may compromise statistical integrity, as women will be withdrawn from the study drug for the duration of the pregnancy. It is therefore imperative for microbicide trials to implement effective contraceptive and pregnancy management programmes that maintain low pregnancy rates and the safety of unborn babies while not compromising the conduct and statistical integrity of the trial.

Overview of microbicides for the prevention of human immunodeficiency virus

Human immunodeficiency virus (HIV) prevention tools that women can use and control are urgently needed. Microbicides are chemical products applied to the vagina or rectum to prevent the sexual transmission of HIV. Four classes of candidate microbicides have been tested to date: those that (1) enhance the natural defences in the vagina to inactivate HIV; (2) inactivate HIV in the vagina; (3) prevent HIV from attaching to, and fusing with, the host cells; and (4) prevent HIV from replicating in genital tract host cells. Despite numerous disappointing efficacy trial results over the past 20 years, substantial progress is now being made in microbicide development after the release of the CAPRISA 004 trial, which provided proof-of-concept that topical antiretroviral microbicides can prevent sexual transmission of HIV and herpes simplex type-2 infection. Microbicides, which fill an important gap for women-controlled prevention methods, have the potential to alter the course of the HIV pandemic.

Microbicides: still a long road to success

The development of efficient microbicides, the topically applied compounds that protect uninfected individuals from acquiring HIV-1, is a promising strategy to contain HIV-1 epidemics. Such microbicides should of course possess anti-HIV-1 activity, but they should also act against other genital pathogens, which facilitate HIV-1 transmission. The new trend in microbicide strategy is to use drugs currently used in HIV-1 therapy. The success of this strategy is mixed so far and is impaired by our limited knowledge of the basic mechanisms of HIV-1 transmission as well as by the inadequacy of the systems in which microbicides are tested in preclinical studies.

Hyperimmune bovine colostrum as a low-cost, large-scale source of antibodies with broad neutralizing activity for HIV-1 envelope with potential use in microbicides

Bovine colostrum (first milk) contains very high concentrations of IgG, and on average 1 kg (500 g/liter) of IgG can be harvested from each immunized cow immediately after calving. We used a modified vaccination strategy together with established production systems from the dairy food industry for the large-scale manufacture of broadly neutralizing HIV-1 IgG. This approach provides a low-cost mucosal HIV preventive agent potentially suitable for a topical microbicide. Four cows were vaccinated pre- and/or postconception with recombinant HIV-1 gp140 envelope (Env) oligomers of clade B or A, B, and C. Colostrum and purified colostrum IgG were assessed for cross-clade binding and neutralization against a panel of 27 Env-pseudotyped reporter viruses. Vaccination elicited high anti-gp140 IgG titers in serum and colostrum with reciprocal endpoint titers of up to 1 × 10(5). While nonimmune colostrum showed some intrinsic neutralizing activity, colostrum from 2 cows receiving a longer-duration vaccination regimen demonstrated broad HIV-1-neutralizing activity. Colostrum-purified polyclonal IgG retained gp140 reactivity and neutralization activity and blocked the binding of the b12 monoclonal antibody to gp140, showing specificity for the CD4 binding site. Colostrum-derived anti-HIV antibodies offer a cost-effective option for preparing the substantial quantities of broadly neutralizing antibodies that would be needed in a low-cost topical combination HIV-1 microbicide.

Potential role of tenofovir vaginal gel for reduction of risk of herpes simplex virus in females

A surprising result of the groundbreaking CAPRISA-004 trial, which demonstrated the efficacy of vaginal tenofovir 1% gel in reducing the risk of human immunodeficiency virus (HIV)-1 infection by 39% in heterosexual women, was the added benefit of this microbicide in reducing acquisition of herpes simplex virus type 2 (HSV-2) by 51%. HSV-2 is the most common cause of genital ulcer disease worldwide, and is responsible for considerable morbidity among women and neonates. The virus is further implicated in increasing the risk of both HIV acquisition and transmission, and may have additional adverse consequences in HIV-coinfected persons, making HSV-2 prevention an important clinical and public health objective. While tenofovir had not previously been widely considered to be an anti-herpes drug, in vitro activity against HSV is well documented, raising interest in potential future applications of tenofovir and its prodrugs in HSV-2 control. This article reviews the currently available data for tenofovir as an anti-herpes agent, as well as unanswered questions about delivery systems, drug formulation, rectal administration, drug resistance, and clinical applications.

Population-level impact of hormonal contraception on incidence of HIV infection and pregnancy in women in Durban, South Africa

OBJECTIVE

To estimate the potential impact of using hormonal contraceptives on rates of infection with human immunodeficiency virus type 1 (HIV-1) and pregnancy by theoretically removing the use of hormonal contraceptives from a study population.

METHODS

A prospective cohort study included 3704 HIV-negative women who were enrolled in two biomedical trials that tested two vaginal microbicides (PRO 2000 and Carraguard®) for the prevention of HIV-1 in Durban, South Africa, in 2004-2009. Cox proportional hazards regression models along with partial population attributable risks (PARs) and their 95% confidence intervals (CIs) were calculated to assess the relative population-level impact of the use of hormonal contraceptives on HIV-1 seroconversion rates and on pregnancy rates.

FINDINGS

Women who reported using hormonal contraceptives at enrolment in the trial had a higher risk of HIV-1 seroconversion (adjusted hazards ratio: 1.24; 95% CI: 0.97-1.58) than women who reported using other types of contraceptives at enrolment. At the population level, the use of hormonal contraceptives (pills or injectables) at baseline and during study follow-up accounted for approximately 20% (95% CI: 16-22) of HIV-1 seroconversions. However, the partial PAR indicated a relative impact of 12% (95% CI: 9.0-15.7). On the other hand, 72% (95% CI: 66-77) of the pregnancies could have been avoided if all women had used hormonal contraceptives.

CONCLUSION

Women using hormonal contraceptives need comprehensive counselling on simultaneous prevention of HIV-1 infection.

Topical microbicides for prevention of sexually transmitted infections

BACKGROUND

Two decades of research on topical microbicides for prevention of sexually transmitted infections (STIs) have had limited success. However, new microbicide randomised controlled trial (RCT) data have recently been published; but these have not yet been the subject of a systematic review.

OBJECTIVES

To determine the effects of topical microbicides for prevention of the acquisition of STIs, including human immunodeficiency virus (HIV) infection, by women from men and by men who have sex with men (MSM).

SEARCH METHODS

In July 2011 we searched the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, EMBASE, Web of Science, NLM Gateway, CLIB, AIDS Education Global Information System, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform; handsearched reference lists of relevant articles and contacted relevant organisations and experts.

SELECTION CRITERIA

RCTs of topical microbicides (except Nonoxynol-9) in sexually active, HIV-negative women or MSM. We excluded Nonoxynol-9 because previous systematic reviews showed that it does not have a significant effect on HIV or STIs.

DATA COLLECTION AND ANALYSIS

We assessed study eligibility, extracted data and assessed risk of bias in duplicate; resolving differences by discussion and consensus. We then conducted fixed-effect meta-analysis, stratified by type of microbicide.

MAIN RESULTS

We found that by the end of 2011, nine microbicide RCTs had either been conducted to term (one BufferGel and 0.5% PRO 2000, one Carraguard and one tenofovir trial) or stopped early due to safety concerns (two cellulose sulphate trials) or insufficient rate of HIV infection and low likelihood of showing a protective effect (one 2% PRO 2000, one tenofovir and two SAVVY trials). The nine RCTs enrolled 31,941 sexually active women between 2004 and 2011; in Benin, Ghana, Malawi, Nigeria, South Africa, Tanzania, Uganda, Zambia, Zimbabwe, India, and the US. A small proof-of-concept RCT found that tenofovir (a nucleotide reverse transcriptase inhibitor) reduced the risk of HIV acquisition (one trial, 889 women; risk ratio (RR) 0.63; 95% CI 0.43 to 0.93). Effectiveness data are not yet available from the second tenofovir RCT that enrolled 5000 women and was stopped early due to low likelihood of showing a protective effect. We found no evidence of an effect on HIV acquisition for cellulose sulphate (2 trials, n = 3069; RR 1.20; 95% CI 0.74 to 1.95), SAVVY (two trials, n = 4295; RR 1.38; 95% CI 0.79 to 2.41), Carraguard (one trial, n = 6202; RR 0.89; 95% CI 0.71 to 1.11), PRO 2000 (two trials, n = 12,486; RR 0.93, 95% CI 0.77 to 1.14) and BufferGel (one trial, n = 1546; RR 1.05; 95% CI 0.73 to 1.52). Tenofovir reduced the incidence of herpes simplex virus type 2 (HSV-2) infection (one trial, 426 women; RR 0.55; 95% CI 0.37 to 0.83) and cellulose sulphate reduced the risk of chlamydia infection (two trials, n = 3069; RR 0.70, 95% CI 0.49 to 0.99). However, there was no evidence of an effect of any microbicide on the acquisition of gonorrhoea, syphilis, condyloma acuminatum, trichomoniasis, or human papillomavirus (HPV) infection. A substudy of the Carraguard trial found the prevalence of high-risk HPV infection (HR-HPV) to be 23.5% in women on Carraguard and 23.0% on placebo (n = 1718; RR 1.02; 95% CI 0.86 to 1.21). After controlling for HR-HPV risk factors, the authors found that compliant Carraguard users were 0.62 (95% CI 0.41 to 0.94) times as likely to be HR-HPV positive as compliant placebo users. Overall, there was no significant difference in the incidence of adverse events between microbicide and placebo groups.

AUTHORS' CONCLUSIONS

Limited evidence suggests that vaginal tenofovir microbicides may reduce the risk of acquisition of HIV and HSV-2 infections in women; but other types of topical microbicides have not shown evidence of an effect on HIV or STI acquisition. Therefore, there is not enough evidence to recommend topical microbicides for HIV or STI prevention at present. Further studies are needed to confirm the beneficial effects of tenofovir microbicide gel in vaginal sex. In addition, further research should continue on the development and testing of new microbicides. If the effectiveness of the tenofovir and/or other microbicides is confirmed in further studies, there will need to be a clear pathway to rapid regulatory approval. Successful launch of the effective gel would depend on having in place appropriate mechanisms for distribution to the women who need it, along with a strategy for ensuring that they use it correctly.

Acceptability of a carrageenan-based candidate vaginal microbicide and matching placebo: findings from a phase II safety trial among women in Chiang Rai, Thailand

OBJECTIVE

To evaluate extended acceptability of vaginal use of a carrageenan-based candidate microbicide and placebo in northern Thai women.

METHODS

As part of a randomized, placebo-controlled, triple-blinded clinical trial, women were asked to insert gel with each vaginal sex act and at least three times per week for 1 year. Used applicators were collected monthly; acceptability questions were asked quarterly.

RESULTS

One hundred sixty-five women were enrolled (83 microbicide, 82 placebo); 148 (90%) remained in the study for 12 months. Gel use was high, with > or =87% returning at least three used applicators per week at each visit. Although acceptability was generally high, some decline in positive reporting was noted in terms of ease of application, timing of gel insertion, and gel volume over time. Approximately one quarter reported gel use increased her sexual pleasure. Over one quarter reported that gel volume of 5 mL was too much. All women with a steady partner at 12 months reported talking to their partner about using the gel. Only 2 women spontaneously mentioned being able to use a product covertly as one of the most appealing attributes of a potential microbicide.

CONCLUSIONS

Although women in this study generally reported high acceptability and use, some found 5 mL of gel to be too much. Focusing on enhanced sexual pleasure and lubrication may be beneficial for marketing proven microbicides. Development of products will need to balance lubrication and efficacy with perceptions of too much volume. The ability to use a product covertly was not a high priority in this population.

Lignosulfonic acid exhibits broadly anti-HIV-1 activity--potential as a microbicide candidate for the prevention of HIV-1 sexual transmission

Some secondary metabolites from plants show to have potent inhibitory activities against microbial pathogens, such as human immunodeficiency virus (HIV), herpes simplex virus (HSV), Treponema pallidum, Neisseria gonorrhoeae, etc. Here we report that lignosulfonic acid (LSA), a polymeric lignin derivative, exhibits potent and broad activity against HIV-1 isolates of diverse subtypes including two North America strains and a number of Chinese clinical isolates values ranging from 21.4 to 633 nM. Distinct from other polyanions, LSA functions as an entry inhibitor with multiple targets on viral gp120 as well as on host receptor CD4 and co-receptors CCR5/CXCR4. LSA blocks viral entry as determined by time-of-drug addiction and cell-cell fusion assays. Moreover, LSA inhibits CD4-gp120 interaction by blocking the binding of antibodies specific for CD4-binding sites (CD4bs) and for the V3 loop of gp120. Similarly, LSA interacts with CCR5 and CXCR4 via its inhibition of specific anti-CCR5 and anti-CXCR4 antibodies, respectively. Interestingly, the combination of LSA with AZT and Nevirapine exhibits synergism in viral inhibition. For the purpose of microbicide development, LSA displays low in vitro cytotoxicity to human genital tract epithelial cells, does not stimulate NF-κB activation and has no significant up-regulation of IL-1α/β and IL-8 as compared with N-9. Lastly, LSA shows no adverse effect on the epithelial integrity and the junctional protein expression. Taken together, our findings suggest that LSA can be a potential candidate for tropical microbicide.

Pregnancy incidence and correlates during the HVTN 503 Phambili HIV vaccine trial conducted among South African women

Background

HIV prevention trials are increasingly being conducted in sub-Saharan Africa. Women at risk for HIV are also at risk of pregnancy. To maximize safety, women agree to avoid pregnancy during trials, yet pregnancies occur. Using data from the HVTN 503/“Phambili” vaccine trial, we report pregnancy incidence during and after the vaccination period and identify factors, measured at screening, associated with incident pregnancy.

Methods

To enrol in the trial, women agreed and were supported to avoid pregnancy until 1 month after their third and final vaccination (“vaccination period”), corresponding to the first 7 months of follow-up. Unsterilized women, pooled across study arms, were analyzed. Poisson regression compared pregnancy rates during and after the vaccination period. Cox proportional hazards regression identified associations with first pregnancy.

Results

Among 352 women (median age 23 yrs; median follow-up 1.5 yrs), pregnancy incidence was 9.6/100 women-years overall and 6.8/100 w-yrs and 11.3/100 w-yrs during and after the vaccination period, respectively [Rate Ratio = 0.60 (0.32–1.14), p = 0.10]. In multivariable analysis, pregnancy was reduced among women who: enrolled at sites providing contraception on-site [HR = 0.43, 95% CI (0.22–0.86)]; entered the trial as injectable contraceptive users [HR = 0.37 (0.21–0.67)] or as consistent condom users (trend) [HR = 0.54 (0.28–1.04)]. Compared with women with a single partner of HIV-unknown status, pregnancy rates were increased among women with: a single partner whose status was HIV-negative [HR = 2.34(1.16–4.73)] and; 2 partners both of HIV-unknown status [HR = 4.42(1.59–12.29)]. Women with 2 more of these risk factors: marijuana use, heavy drinking, or use of either during sex, had increased pregnancy incidence [HR = 2.66 (1.24–5.72)].

Conclusions

It is possible to screen South African women for pregnancy risk at trial entry. Providing injectable contraception for free on-site and supporting consistent condom use may reduce incident pregnancy. Screening should determine the substance use, partnering, and HIV status of both members of the couple for both pregnancy and HIV prevention.

Trial Registration

SA National Health Research Database DOH-27-0207-1539; Clinicaltrials.gov NCT00413725

UC781 microbicide gel retains anti-HIV activity in cervicovaginal lavage fluids collected following twice-daily vaginal application

The potent nonnucleoside reverse transcriptase inhibitor UC781 has been safety tested as a vaginal microbicide gel formulation for prevention of HIV-1 sexual transmission. To investigate whether UC781 retained anti-infective activity following exposure to the female genital tract, we conducted an ex vivo analysis of the UC781 levels and antiviral activity in cervicovaginal lavage (CVL) fluids from 25 Thai women enrolled in a 14-day safety trial of twice-daily vaginal application of two concentrations of the UC781 microbicide gel. CVL samples were collected from women in the 0.1% (n = 5), 0.25% (n = 15), and placebo (n = 5) gel arms following the first application of gel (T(15 min)) and 8 to 24 h after the final application (T(8-24 h)) and separated into cell-free (CVL-s) and pelletable (CVL-p) fractions. As UC781 is highly hydrophobic, there were significantly higher levels of UC781 in the CVL-p samples than in the CVL-s samples for the UC781 gel arms. In T(8-24 h) CVL-p samples, 2/5 and 13/15 samples collected from the 0.1% and 0.25% UC781 gel arms, respectively, efficiently blocked infection with ≥ 4 log(10) 50% tissue culture infective dose (TCID(50)) of a CCR5-tropic CRF01_AE HIV-1 virus stock. Independent of the arm, the 11 CVL-p samples with UC781 levels of ≥ 5 μg/CVL sample reduced infectious HIV by ≥ 4 log(10) TCID(50). Our results suggest that the levels and anti-infective activities of UC781 gel formulations are likely to be associated with a cellular or pelletable component in CVL samples. Therefore, cellular and pelletable fractions should be assayed for drug levels and anti-infective activity in preclinical studies of candidate microbicides.

Mucosal HIV-1 transmission and prevention strategies in BLT humanized mice

Clinical trials testing microbicides and related biomedical interventions to block HIV transmissions have produced contradictory results and to date it is unclear why. Further elucidation of the molecular basis of mucosal HIV transmission and extensive pharmacokinetic and pharmacodynamic analyses are essential to implementing effective prevention strategies. Animal models are of critical importance to this effort and bone marrow-liver-thymus (BLT) humanized mice have recently emerged as a powerful small animal research platform for in vivo efficacy evaluation of mucosal and parenteral HIV-1 prevention interventions. The availability of this validated system for the pre-clinical evaluation of HIV-1 prevention approaches will accelerate the implementation of the best candidate interventions into clinical trials.

Heparosan-derived heparan sulfate/heparin-like compounds: one kind of potential therapeutic agents

Heparan sulfate (HS) is a highly sulfated glycosaminoglycan and exists in all animal tissues. HS and heparin are very similar, except that heparin has higher level of sulfation and higher content of iduronic acid. Despite the fact that it is a century-old drug, heparin remains as a top choice for treating thrombotic disorders. Pharmaceutical heparin is derived from porcine intestine or bovine lung via a long supply chain. This supply chain is vulnerable to the contamination of animal pathogens. Therefore, new methods for manufacturing heparin or heparin-like substances devoid of animal tissues have been explored by many researchers, among which, modifications of heparosan, the capsular polysaccharide of Escherichia coli K5 strain, is one of the promising approaches. Heparosan has a structure similar to unmodified backbone of natural HS and heparin. It is feasible to obtain HS or heparin derivatives by modifying heparosan with chemical or enzymatic methods. These derivatives display different biological activities, such as anticoagulant, anti-inflammatory, anticancer, and antiviral activities. This review focuses on the recent studies of synthesis, activity, and structure-activity relationship of HS/heparin-like derivatives prepared from heparosan.

The cost-effectiveness of pre-exposure prophylaxis for HIV infection in South African women

BACKGROUND

Recent trials report the short-term efficacy of tenofovir-based pre-exposure prophylaxis (PrEP) for prevention of human immunodeficiency virus (HIV) infection. PrEP's long-term impact on patient outcomes, population-level transmission, and cost-effectiveness remains unknown.

METHODS

We linked data from recent trials to a computer model of HIV acquisition, screening, and care to project lifetime HIV risk, life expectancy (LE), costs, and cost-effectiveness, using 2 PrEP-related strategies among heterosexual South African women: (1) women receiving no PrEP and (2) women not receiving PrEP (a tenofovir-based vaginal microbicide). We used a South African clinical cohort and published data to estimate population demographic characteristics, age-adjusted incidence of HIV infection, and HIV natural history and treatment parameters. Baseline PrEP efficacy (percentage reduction in HIV transmission) was 39% at a monthly cost of $5 per woman. Alternative parameter values were examined in sensitivity analyses.

RESULTS

Among South African women, PrEP reduced mean lifetime HIV risk from 40% to 27% and increased population discounted (undiscounted) LE from 22.51 (41.66) to 23.48 (44.48) years. Lifetime costs of care increased from $7280 to $9890 per woman, resulting in an incremental cost-effectiveness ratio of $2700/year of life saved, and may, under optimistic assumptions, achieve cost savings. Under baseline HIV infection incidence assumptions, PrEP was not cost saving, even assuming an efficacy >60% and a cost <$1. At an HIV infection incidence of 9.1%/year, PrEP achieved cost savings at efficacies ≥50%.

CONCLUSIONS

PrEP in South African women is very cost-effective by South African standards, conferring excellent value under virtually all plausible data scenarios. Although optimistic assumptions would be required to achieve cost savings, these represent important benchmarks for future PrEP study design.

The effectiveness of Carraguard, a vaginal microbicide, in protecting women against high-risk human papillomavirus infection

BACKGROUND

A randomised, double-blind, placebo-controlled trial found the vaginal microbicide Carraguard unable to prevent HIV infection. A substudy assessed the association of genital high-risk human papillomavirus (HR-HPV) in women at study end with Carraguard use.

METHODS

Participants received Carraguard gel or placebo plus condoms, and were instructed to use gel plus condoms during each act of vaginal intercourse. HR-HPV detection on cervical samples from 1,723 women was by Digene Hybrid Capture 2 analysis. Poisson regression analysis assessed the prevalence of genital HR-HPV for individuals receiving Carraguard relative to individuals receiving placebo.

RESULTS

In the Carraguard arm (n=875) the end trial unadjusted HR-HPV prevalence was 23.5% (95% CI 20.8-26.3) and 23.0% (95% CI 20.2-25.8) in placebo arm (n=843). Significant risk factors for HR-HPV infection were younger age, being single, an abnormal pap smear, multiple sexual partners and promiscuous behaviour without the use of a condom. There were 348 compliant women (174 Carraguard, 174 placebo users), with relatively high adherence to gel use, who inserted 80% of their opened, returned applicators of test product with the proportion of applicator insertions to sex acts >30%. After adjusting for risk factors, these compliant Carraguard users were 0.62 as likely to be classified HR-HPV positive (95% CI 0.41-0.94) as compliant placebo users.

CONCLUSIONS

The prevalence of HR-HPV infection was lower in compliant Carraguard users than compliant placebo users. To our knowledge, this is the first report showing a negative association of HPV infection with a vaginal microbicide.

Pregnancy and contraceptive use among women participating in an HIV prevention trial in Tanzania

Objectives

Information on pregnancy rates and factors associated with pregnancy and contraceptive use is important for clinical trials in women in sub-Saharan Africa where withdrawal of investigational products may be required in the event of pregnancy with a consequent effect on sample size and trial power.

Methods

A prospective cohort analysis of pregnancy and contraceptive use was conducted in Tanzanian women enrolled in a randomised placebo-controlled trial of herpes simplex virus-suppressive therapy with acyclovir to measure the effect on HIV incidence in HIV-negative women and on genital and plasma HIV viral load in HIV-positive women. The cohort was followed every 3 months for 12–30 months. Women at each visit were categorised into users or non-users of contraception. Pregnancy rates and factors associated with pregnancy incidence and contraceptive use were measured.

Results

Overall 254 of 1305 enrolled women became pregnant at least once during follow-up (pregnancy rate: 12.0/100 person-years). Younger age, being unmarried, higher baseline parity and changes in contraceptive method during follow-up were independently associated with pregnancy. Having paid sex and being HIV positive were associated with lower risk of pregnancy. Uptake of contraception was associated with young age, being unmarried, occupation, parity and the number and type of sexual partners.

Conclusions

Data on use of contraceptive methods and risk factors for pregnancy can help to guide decisions on trial eligibility and the need for additional counselling. Mandatory reliable contraceptive use in study participants may be required to reduce pregnancy rates in studies where pregnancy is contraindicated.