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Microbicide news: Eyeing data on Invisible Condom
With results just published for a Phase I clinical trial and data for a Phase I/II trial in analysis, developers of what is being dubbed the Invisible Condom are looking toward initiation of a Phase III randomized controlled trial to test the safety and efficacy of the potential microbicide.1
Developed by researchers at the Infectious Diseases Research Centre at the Université Laval in Québec, the Invisible Condom offers a physical barrier in the form of a gel that blocks the entry of pathogens into the mucosa, and a chemical barrier, sodium lauryl sulfate, within the gel that kills sexually transmitted pathogens including HIV.2,3 The Canadian research team also has designed a special applicator that delivers the product uniformly throughout the vagina and cervix.
The current published paper reports the results of a Phase I trial conducted among 41 women and 23 men in the Quebec City region. The trial was designed with three cohorts: sexually abstinent women applying gel twice daily for 14 days; sexually active women with tubal ligation applying gel once daily for 14 days and their sexual partners who did not use gel; and women on oral contraceptives applying gel once daily and their sexual partners. Women had to be healthy and be between ages 18-49. A follow-up was conducted following the 14 days of gel application.
No serious adverse events were reported during the trial, report the research team. Colposcopy examination showed no genital ulceration or epithelial lesions, and no major changes in vaginal flora or vaginal pH were detected. None of the women had to stop product application due to adverse events. Common side effects were itching, dryness, burning sensation, erythema, and discharge. Results of a satisfaction questionnaire showed that the gel and applicator were acceptable.1
A separate Phase I/II placebo-controlled trial has been conducted in Cameroon, says study co-author Rabeea Omar, PhD, CCRP, an associate professor at the Université and project chief of its Infectious Diseases Research Centre. Results of the trial, conducted among 452 healthy women, are in analysis, he reports. The research teams plans to publish the results upon analysis completion, says Omar. Funding is being sought for a Phase III trial; scientists hope to enroll 5,000 women in the Phase III study, says Omar.
Look for new developments on the microbicides front to stem from Microbicides 2008, scheduled for Feb. 24-27 in New Delhi, India. At press time, the Université Laval research team was scheduled to present a poster at the international conference.
Of special interest this year is the anticipated results of the large-scale efficacy trial of Carraguard, says Anna Forbes, MSS, deputy director of the Global Campaign for Microbicides, an international coalition of organizations working to accelerate access to new HIV prevention options. Carraguard, developed by the Population Council, is an odorless, tasteless, clear gel made from carrageenan, a derivative of seaweed.
More than 6,000 women were enrolled and randomly assigned to use Carraguard or a placebo gel an hour or less before each act of vaginal intercourse. The trial was conducted at three sites in South Africa: the Setshaba Research Centre, through the University of Limpopo/Medunsa campus; the Empilisweni Centre for Wellness Studies, through the University of Cape Town; and the Isipingo Clinic, through the Medical Research Council of South Africa. Data collection for the Phase III trial was completed in March 2007.
The year 2007 saw the cessation of two advanced trials of cellulose sulfate, which was eyed as a potential microbicidal candidate. One trial, conducted by CONRAD, was halted after preliminary results indicated it could lead to an increased risk of HIV infection in women who use the compound. A separate advanced study, conducted by Family Health International, was closed after scientists determined there was no evidence that the product was effective in preventing HIV. How did this news affect microbicide development?
I think that microbicide research is very much on track," observes Forbes. "I think what is really important for people to understand is that trials being stopped and products not working is absolutely par for the course in research into any new drug development."
With scientists continually learning more about how to test potential drugs, as well as identifying potential markers for safety and efficacy, the state of microbicides may well be at the same point as was seen with antiretroviral drugs in 1994, prior to proof of concept, says Forbes. "Once we know what works, it becomes much easier to look back and say, 'What reasonably can be considered to be the surrogate markers of this efficacy?'" states Forbes. "But right now, we are in the process of still having to look forward and not knowing what constitutes a marker, because we don't yet have proof of concept."