Thinking about vaginal microbicide testing

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.

A non-paternalistic model of research ethics and oversight: assessing the benefits of prospective review

This paper offers a non-paternalistic justification for prospective research review as providing a credible social assurance that the institutions of scientific advancement respect and affirm the moral equality of all community members and as creating a "market" in which stakeholders working to advance diverse ends also advance the common good.

Weighing the gold in the gold standard: challenges in HIV prevention research

OBJECTIVE(S)

Few HIV prevention interventions have been evaluated in randomized controlled trials (RCTs). We examined design, implementation, and contextual considerations that may limit detection of a positive or adverse effect in HIV prevention trials.

DESIGN

A systematic review of late phase RCTs for prevention of sexual transmission of HIV that randomly allocated intervention and comparison groups; evaluated interventions to prevent sexual transmission in nonpregnant populations; and reported HIV incidence as the primary or secondary outcome.

METHODS

PubMed/MEDLINE, other electronic databases, and electronic conference proceedings of recent HIV/AIDS-related conferences were searched to identify published or unpublished trials meeting the inclusion criteria. Descriptive, methodological, and contextual factors were abstracted from each trial.

RESULTS

The review included 37 HIV prevention RCTs reporting on 39 unique interventions. Only six RCTs, all evaluating biomedical interventions, demonstrated definitive effects on HIV incidence. Five of the six RCTs significantly reduced HIV infection: all three male circumcision trials, one trial of sexually transmitted infection treatment and care, and one vaccine trial. One microbicide trial of nonoxynol-9 gel produced adverse results. Lack of statistical power, poor adherence, and diluted versions of the intervention in comparison groups may have been important issues for the other trials that demonstrated 'flat' results.

CONCLUSION

Almost 90% of HIV prevention trials had 'flat' results, which may be attributable to trial design and/or implementation. The HIV prevention community must not only examine evidence from significant RCTs, but must also examine flat trials and address design and implementation issues that limit detection of an effect.

Evaluation of dendrimer SPL7013, a lead microbicide candidate against herpes simplex viruses

Dendrimers are a novel class of polyanionic macromolecules with broad-spectrum antiviral activities and minimal toxicities. A new generation of amide dendrimer, SPL7013, was evaluated as a lead microbicide candidate against herpes simplex viruses (HSV). The plaque reduction assays showed that the 50% effective concentrations (EC(50)) determined by pre-treatment of cells were 2.0 microg/ml for HSV-1 and 0.5 microg/ml for HSV-2. Inhibitory effects were also observed on HSV-infected cells with EC(50)s of 6.1 microg/ml for HSV-1 and 3.8 microg/ml for HSV-2. These are the mean values from the test results of six batches of SPL7013. SPL7013 was also shown to be equally potent against HSV drug-resistant strains. SPL7013 completely inhibited viral adsorption to Vero cells at concentrations of higher than 3 microg/ml. Analyzed by a LightCycler assay after treatment of HSV-infected cells for 17 h, SPL7013 showed strong inhibition of HSV DNA synthesis with EC(50)s of approximately 6.2 and 2.0 microg/ml for HSV-1 and HSV-2, respectively. SPL7013 retained its anti-HSV activity even after treatment at acidic pHs 3.0 and 4.0 for 2 h. The presence of 10% human serum proteins did not affect the anti-HSV activity of SPL7013. SPL7013 was not toxic to Vero cells up to the highest concentration tested (10,000 microg/ml). Effects on cell proliferation were tested on two epithelial cell lines in both stationary and dividing phases. The 50% cytotoxic concentrations (CC(50)) in all cases were greater than 10,000 microg/ml. Our data indicate that SPL7013 is a promising candidate for development as a vaginal microbicide and a therapeutic agent.

Microbicide trials for preventing HIV/AIDS in South Africa: phase II trial partricipants' experiences and psychological needs

The Microbicide Division of the Department of Medical Microbiology at MEDUNSA, South Africa, recently completed a phase II expanded safety trial of the candidate microbicide Carraguard. A microbicide is a vaginal product that women might use, if proven safe and effective, to protect themselves from HIV and possibly other sexually transmitted infections (STIs). The study participants were from Ga-Rankuwa and its neighbouring areas, an historically disadvantaged residential township near Pretoria. We conducted six focus group discussions with phase II trial participants to evaluate their experiences with trial participation and their psychological needs. Participants spontaneously talked about their experiences with the study gel and speculum examinations. They felt that they had received high quality medical care. They indicated that their personal hygiene and knowledge of the female reproductive system, HIV and other STIs had improved, which helped their familie and empowered them as women. Participants valued being able to discuss their anxiety about HIV/AIDS wit study staff. They felt that the study provided them with a supportive environment in which their personal problems (not necessarily restricted to HIV/AIDS) could be addressed. Some recommended that the study staf improve their professionalism and punctuality. They suggested the formation of participant support groups, an expressed a preference to remain involved in the trial. Some participants appeared to have become dependent o services provided during the trial. We have taken the results of these focus group discussions into account during planning for a phase III efficacy trial of Carraguard to be conducted in the same and other similar communities.

Vaginal microbicides and teenagers

PURPOSE OF REVIEW

Sexually active teens are at significant risk from sexually transmitted infections and girls and women bear the greatest burden of these infections. New methods, such as vaginal microbicides, would provide female controlled options. Microbicides are currently in development and thus it is timely to discuss the progress made and factors that may influence acceptability for teens.

RECENT FINDINGS

Microbicide development presents many challenges, and several different potential mechanisms of action are being explored. There is interest in these products from women and men, and specific preferences are being investigated. Adolescents, due to reproductive system immaturity, developing cognitive abilities and the psychosocial context of their relationships, present a special set of challenges in efforts to foster microbicide use.

SUMMARY

Vaginal microbicides are on the horizon. Further study into teen issues is required to develop successful strategies for marketing and encouraging adolescent use of microbicides.

Microbicides and HIV: help or hindrance?

We present a simple mathematical model for assessing the effects of introducing a microbicide as an HIV infection protective method. As very little is known about the in vivo efficacy of microbicides, we ran sample scenarios for microbicides of various efficacies. We found that, in general, if existing condom usage in a community is low, introducing a microbicide will most likely have a positive impact on HIV incidence as abandonment of condom use in favor of microbicides will not play a significant role. If condom use in a community is high, though, attrition of condom users could play a role large enough to overwhelm any added risk reduction afforded new microbicide users. Our model illustrates the importance of knowing key behavioral parameters, such as the proportion of the population that uses condoms, before microbicides can be safely introduced. These parameters include the proportion of condom users likely to maintain condom use and the proportion of condom nonusers likely to adopt microbicides, as well as the efficacy of the candidate microbicide.

Recommendations for the clinical development of topical microbicides: an update

Topical microbicides are products that are being developed to prevent HIV infection and other sexually transmitted diseases (STD) through topical application to the genital and rectal epithelial surfaces. This paper is an update of the clinical section of a general guidance for the development and evaluation of microbicidal products that was first published by the International Working Group on Microbicides (IWGM) in 1996. (The preclinical section of that document will be updated separately later.) All topical microbicides should be clinically evaluated in humans for safety and effectiveness. Safety studies are necessary to evaluate the potential for systemic absorption and toxicity as well as local toxic effects, such as irritation, ulceration, burning, and itching. Reported symptoms of burning and itching are relevant to future product use and acceptability. Irritation and ulceration of the vaginal, cervical, penile, or rectal epithelium have the potential to result in an increased transmission of HIV and other STD. Effectiveness studies to assess the prevention of HIV infection or STD, depending upon the product indication, are subsequently conducted. These trials need to be large enough to detect clinically meaningful levels of protection. For spermicidal microbicides, additional contraceptive effectiveness studies are also needed.