Researchers launch first-ever phase II safety study of rectal microbicide to prevent HIV

October 2, 2013

Taking an important step toward the development of a product to prevent HIV infections associated with unprotected anal sex, researchers today announced the launch of a global Phase II clinical trial of a potential rectal microbicide. The trial, led by the U.S. National Institutes of Health (NIH)-funded Microbicide Trials Network (MTN), is testing the rectal use of a reduced glycerin gel formulation of the antiretroviral drug tenofovir.

"As the HIV epidemic continues to impact people worldwide, we urgently need new ways to prevent sexual transmission of the virus, especially from unprotected anal sex – the highest risk sexual behavior for HIV acquisition," said Ross D. Cranston, M.D., of the University of Pittsburgh School of Medicine, who is leading the study with Javier R. Lama, M.D., M.P.H., of IMPACTA in Lima, Peru. "Rectal microbicides, gel-based antiretroviral products applied into the rectum, are being developed for use by both men and women to help reduce this risk."

Known as MTN-017, the Phase II study will enroll 186 HIV-negative men who have sex with men (MSM) and transgender women in Peru, South Africa, Thailand and the United States, including Puerto Rico, to assess the safety of a reduced glycerin gel formulation of tenofovir, its acceptability to , and how much of the drug is absorbed into the body. It is a follow-up trial to an earlier study, MTN-007, which found that the reduced glycerin gel was safe and acceptable to both men and women who used it in the rectum daily for a one-week period.

During MTN-017, will cycle through three study regimens, each lasting eight weeks: reduced glycerin tenofovir gel used daily, reduced glycerin tenofovir gel used before and after anal sex, and daily use of the antiretroviral tablet Truvada® (emtricitabine/tenofovir disoproxil fumarate), developed by Gilead Sciences, Inc. This design will allow researchers to collect information about the gel's safety and acceptability in the rectum, and compare it to the use of oral Truvada, which was approved for use as HIV prevention by the U.S. Food and Drug Administration in 2012. Truvada was approved for the treatment of HIV infection in combination with other antiretrovirals in 2004.

"The results of MTN-017 will be vitally important to the biomedical HIV prevention field," explained Dr. Lama. "They will determine whether we can move ahead with further testing of the gel's effectiveness in preventing the transmission of HIV from unprotected anal sex. We know that rectal microbicides will never replace condoms, but if found safe and effective, they could provide an additional tool to help reduce HIV risk."

Throughout the study, researchers will regularly test participants' blood to assess the presence of drug – a determinant of whether they are using their assigned study products. Testing will be conducted every four weeks and results will then be shared with participants as part of their counseling sessions on product use.

"By monitoring product use as the study is underway, we will have a much better sense of whether participants are adhering to the assigned study regimens," said Ian McGowan, M.D., Ph.D., co-principal investigator of the MTN and professor of medicine, University of Pittsburgh School of Medicine. "The unique design of our study, which does not include a placebo, allows us to address any concerns or issues with adherence in a more real-time fashion, rather than waiting until after the study has concluded."

MTN-017 will be conducted at the following trial sites, pending necessary approvals: In Peru – the IMPACTA Clinical Research Site in Lima; in South Africa – the Desmond Tutu HIV Foundation in Cape Town; in Thailand – the Research Institute for Health Sciences in Chiang Mai and the Thailand MOPH-US CDC Collaboration in Bangkok; and, in the United States – The Fenway Institute in Boston; the University of Pittsburgh; the San Francisco Department of Public Health, and the University of Puerto Rico Maternal-Infant Studies Center in San Juan.

The study is being conducted through the MTN, which is funded by the National Institute of Allergy and Infectious Diseases (NIAID), the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Institute of Mental Health, all part of the NIH. The study products are being provided by Gilead Sciences, Inc., of Foster City, Calif., and by CONRAD, of Arlington, Va. Truvada is a registered trademark of Gilead Sciences. In 2006, Gilead assigned a royalty-free license for tenofovir gel to CONRAD and the International Partnership for Microbicides of Silver Spring, Md.

CONRAD developed the reduced glycerin formulation of tenofovir gel being evaluated in MTN-017, which differs from the formulation originally developed for vaginal use. It did so in response to an earlier study called RMP-02/MTN-006, which found that the vaginal gel caused gastrointestinal side effects in some study participants.

The vaginal formulation of tenofovir gel continues to be evaluated for preventing the transmission of HIV through vaginal sex in women. Ongoing is a Phase III trial called FACTS 001 that is testing its use before and after sex among women in South Africa, with results expected in 2015. FACTS 001 hopes to replicate the results of CAPRISA 004, which found this regimen reduced the risk of HIV by 39 percent compared to placebo gel. The VOICE Study (Vaginal and Oral Interventions to Control the Epidemic), however, found daily use of the gel not effective among its study participants; most of the women did not use the product daily as recommended.

Explore further: Gel safe and acceptable as approach to preventing HIV from anal sex

Related Stories

Gel safe and acceptable as approach to preventing HIV from anal sex

April 3, 2013
A reformulated version of an anti-HIV gel developed for vaginal use was found safe and acceptable by HIV-negative men and women who used it rectally, according to a Phase I clinical trial published today in PLOS ONE. The ...

Rectal formulation of tenofovir gel safe and acceptable in early phase clinical study

March 6, 2012
A gel formulation of the antiretroviral drug tenofovir designed specifically for rectal use was found safe and acceptable, according to a Phase I clinical study led by the U.S. National Institutes of Health (NIH)-funded Microbicide ...

Reduced glycerin formulation of tenofovir vaginal gel safe for rectal use

May 17, 2012
A change in the formulation of tenofovir gel, an anti-HIV gel developed for vaginal use, may make it safer to use in the rectum, suggests a study published online this week in the Journal of Antimicrobial Chemotherapy. In ...

Tenofovir Gel wins out in drug absorption study, but HIV prevention trials say differently

January 30, 2013
A novel head-to-head study looking at differences in how the antiretroviral (ARV) drug tenofovir gets absorbed in the body as either an oral tablet or a vaginal gel found tenofovir gel can achieve substantially higher concentrations ...

Recommended for you

Scientists divulge latest in HIV prevention

July 25, 2017
A far cry from the 1990s "ABC" campaign promoting abstinence and monogamy as HIV protection, scientists reported on new approaches Tuesday allowing people to have all the safe sex they want.

Girl's HIV infection seems under control without AIDS drugs

July 24, 2017
A South African girl born with the AIDS virus has kept her infection suppressed for more than eight years after stopping anti-HIV medicines—more evidence that early treatment can occasionally cause a long remission that, ...

Meds by monthly injection might revolutionize HIV care (Update)

July 24, 2017
Getting a shot of medication to control HIV every month or two instead of having to take pills every day could transform the way the virus is kept at bay.

Candidate AIDS vaccine passes early test

July 24, 2017
The three-decade-old quest for an AIDS vaccine received a shot of hope Monday when developers announced that a prototype triggered the immune system in an early phase of human trials.

Paris spotlight on latest in AIDS science

July 21, 2017
Some 6,000 HIV experts gather in Paris from Sunday to report advances in AIDS science as fading hopes of finding a cure push research into new fields.

Scientists elicit broadly neutralizing antibodies to HIV in calves

July 20, 2017
Scientists supported by the National Institutes of Health have achieved a significant step forward, eliciting broadly neutralizing antibodies (bNAbs) to HIV by immunizing calves. The findings offer insights for HIV vaccine ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.