Back to home » Top Stories » IAC 2010
XVIII International AIDS Conference
IAC 2010 XVIII International AIDS Conference
Reed Messe Wien
Vienna, Austria
July 18-23, 2010

emailprint

Tenofovir Microbicidal Gel Significantly Cuts HIV Infection Rate

July 20, 2010

By David Evans

After decades of research, a microbicidal gel—in this case made from the antiretroviral drug tenofovir—has finally proved effective in preventing transmission of HIV in women, cutting the overall infection rate by 39 percent. These data were reported Tuesday, July 20, at the XVIII International AIDS Conference in Vienna and were met with a prolonged standing ovation from delegates in attendance. 

The results were also published online  July 19 in the journal Science.

AIDS researchers have been seeking a biomedical HIV prevention tool since the virus was first isolated 27 years ago. During the past 15 years, given the poor progress being made on a vaccine, much attention has been focused on developing microbicidal gels. Unfortunately, 11 studies of six different products have so far failed to find an effective microbicide, and at least one study found that the microbicide being tested actually placed women at greater risk of contracting HIV.

New findings from CAPRISA indicate an experimental microbicide helps reduce risk of HIV infection.  

Result of CAPRISA 004 reviewed by Quarraisha Abdool Karim during a press conference at the XVIII International AIDS Conference in Vienna.
©IAS/Steve Forrest/Workers' Photos

 
Experts and community advocates have placed much hope, however, in a new group of microbicides that are being developed using existing and experimental drugs initially designed to treat HIV. The first of these to be explored is the drug tenofovir, which in its oral form is sold as Viread (also found in Truvada and Atripla).

Previous studies have reported that a 1 percent tenofovir gel was highly effective at reducing viral transmission in monkeys, either when used daily or intermittently. Small studies in humans found the gel generally safe and well tolerated. The first large study to explore the effectiveness of the gel in humans was the Centre for the AIDS Program of Research in South Africa (CAPRISA) 004 study, the results of which were reported today.

How the Study Worked

CAPRISA 004 enrolled 889 HIV-negative, sexually active women in two areas of South Africa: Durban, an urban center, and a rural area about 150 kilometers outside Durban. Previous preparatory studies found the rate of new HIV infections to be extremely high among women in both regions—about 6 percent of women became infected in the urban location each year, and 11 percent in the rural location.

In the study, women received extensive safer-sex counseling and condoms. They also received single-dose pre-filled applicators that contained either the tenofovir gel or a placebo to use 12 hours before insertive intercourse and within 12 hours after. The women received detailed instructions regarding the proper use of the microbicide, and they received monthly counseling to support adherence throughout the study. Adherence was measured both by self-report and by the return of all used and unused applicator packs to the study sites.

The study’s results were reported at the International AIDS Conference and published in Science by a husband and wife team—Salim Abdool Karim, MD, and Quarraisha Abdool Karim, MD, from the Columbia University Mailman School of Public Health in New York City and CAPRISA in Durban—and their colleagues.

Promising Results

The authors found that the tenofovir gel far out-performed the placebo gel, and that the beneficial effect became evident early on. 

During the 30 months of follow up, 98 women out of the 889 became HIV positive during the trial—with 38 in the tenofovir gel group and 60 in the placebo gel group. The HIV incidence was 5.6 percent in the tenofovir gel group and 9.1 percent in the placebo gel group.

New findings from CAPRISA indicate an experimental microbicide helps reduce risk of HIV infection.  

New findings indicate that an experimental microbicide helps reduce risk of HIV infection. 
Photo credit: Microbicide Trials Network/University of Pittsburgh

 
After factoring in a woman’s sexual activity, condom use and other factors, tenofovir gel cut the HIV infection rate by 39 percent. 

It is worth noting that efficacy dwindled as the study continued. The tenofovir gel cut the HIV infection rate by more than 50 percent at the 12-month study mark, but dropped to 39 percent at the final 2.5-year study mark. This was likely due to adherence fatigue—less consistent use of the gel as time went on.  

In women who remained highly adherent, defined as women who used the gel in more than 80 percent of their sex acts for all 30 months of the study, the drop in transmission remained high—54 percent. With average adherence or poor adherence, the reduction in new infections was 38 and 28 percent, respectively.

“Without this gel, for every 100 women we may see 10 women being infected in a year,” said Salim Abdool Karim, as reported by the U.S. Department of Health and Human Service’s website healthfinder.org. “With this gel, we would see only six women being infected.”

Out of the 434 women who tested negative for herpes at the start of the trial, 29 became infected in the tenofovir group and 58 became infected in the placebo group. This translated into a 51 percent reduction in the rate of genital herpes transmission.

The rate of side effects was similar between those receiving the tenofovir gel and those receiving the placebo gel, though the tenofovir gel users had higher rates of diarrhea. The authors stated that there is no known reason for such an effect. There were four cases of a hepatitis “flare” in women infected with hepatitis B virus (HBV)—a temporary worsening of symptoms of hepatitis-related liver problems—but the four cases were split evenly between those on tenofovir and those on placebo.

Researchers have been concerned that continued use of the gel, after a person becomes infected with HIV, might cause the development of tenofovir-resistant HIV to emerge. Fortunately, in this study, no tenofovir resistance was found in any of those who became infected while using the gel. The authors cautioned that further research will be needed to confirm these results. In fact, another study looking at daily tenofovir gel use is already in progress. It’s likely, however, that an even larger clinical trial might be needed before the gel can be approved and licensed around the world, said Kevin Fenton, MD, PhD, the director of the National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention at the U.S. Centers for Disease Control and Prevention.

On a positive note, one of the great fears of prevention researchers—that women would compensate for a perceived reduction in HIV transmission risk from the gel and use condoms less frequently—did not occur. In fact, reported condom use actually rose during the course of the study.

In contrast, the authors stressed that adherence to the gel was low. “Despite [extensive adherence counseling and support] and high gel acceptability, about 40 percent of the women in this study had below 50 percent gel adherence. Future trials will need to place greater emphasis on enhancing and objectively measuring adherence, in light of its substantial influence on the trial outcome,” they said.

Ultimately, better packaging and a sexier marketing message could help increase adherence.

“This is simply a cylindrical white plastic tube. You can’t get anything more unattractive,” said Salim Abdool Karim. “Even Coke would have gone bankrupt if they had adopted this approach to their marketing. We only made this gel for the study. I think the future is going to involve making this gel sexy, making this gel something that is part-and-parcel of the sex act, that enhances sex. Packaging is part-and-parcel of addressing the adherence issue.”

Search: Tenofovir, microbicide, microbicidal, Viread, Truvada, Atripla, transmission, prevention, CAPRISA 004, Salim Abdool Karim, Quarraisha Abdood Karim, Durban, Herpes, CAPRISA

Scroll down to comment on this story.



Name:

(will display; 2-50 characters)

Email:

(will NOT display)

City:

(will display; optional)

Comment (500 characters left):

(Note: The AIDSmeds team reviews all comments before they are posted. Please do not include ":" "@" "<" ">" in your comment. The opinions expressed by people providing comments are theirs alone. They do not necessarily reflect the opinions of Smart + Strong, which is not responsible for the accuracy of any of the information supplied by people providing comments.)

Comments require captcha.
Please enter this number for verification:

| Posting Rules



Show comments (4 total)

More from AIDS2010

HIV/AIDS Complications

July 28, 2010
Global Survey: Stigma, Isolation and Discrimination Still Pervasive
Universal HIV Treatment Access No Guarantee of Health for Socially Disadvantaged
July 27, 2010
OM-85 BV: A Bacterial Vaccine Against Respiratory Problems in People with HIV and COPD?
Low Vitamin D Levels Not Associated With HIV Drugs
July 23, 2010
Longer Duration of HIV Infection Might Increase the Risk of Brain Disorders
Nearly 75 Percent of People With HIV Might Have Bone Problems
July 22, 2010
Health Care Providers and People With HIV Not Communicating Effectively
July 21, 2010
Non-AIDS Cancers Occurring at Earlier Age Among People With HIV
Hep C Treatment Effective in HIV Patients With Normal Liver Enzymes
Aging Might Have a Smaller Impact on Immune Function Than Suspected
July 20, 2010
Viramune Boosts Hep C Treatment Efficacy in People With HIV
HIV/HCV Coinfection Further Increases Risk of Bone Fractures
Fewer Malignancies Seen in Those Taking Selzentry

Experimental HIV Drugs

July 23, 2010
More Details of TBR-652’s Antiviral and Anti-Inflammatory Potential Reported
July 22, 2010
ViiV HIV Integrase Inhibitor Performing Well in First-Time Treatment Study
Rilpivirine Has Similar Efficacy and Better Tolerability Than Sustiva
Extended-Release Viramune Has Comparable Safety and Efficacy to Standard Viramune
July 20, 2010
New ViiV Integrase Inhibitor Effective Against Some Isentress-Resistant HIV Strains
July 19, 2010
Argos’s Dendritic Cell Therapy Reduces HIV During Treatment Interruption

HIV Transmission and Prevention

July 29, 2010
Prevention Is Failing to Target MSM When They’re Young Enough
July 26, 2010
HPV Cancer Vaccine Effective for Heterosexual, Gay and Bisexual Men
Study Finds PrEP Is Safe in Gay and Bi Men
July 23, 2010
Circumcision Unlikely to Have Major HIV Prevention Benefit Among Gay Men
July 21, 2010
Microbicide Success Story: What It Means and Where We Go Next
MACS: Childhood Sex Abuse and Victimization Linked to Increased HIV Risk
Full-Scale HIV Treatment and Prevention Could Save Millions of Lives
July 20, 2010
Tenofovir Microbicidal Gel Significantly Cuts HIV Infection Rate
HIV Cases in Young People Are Falling Around the World
July 19, 2010
Preliminary Results Suggest Good Safety and Adherence Profile for PrEP

Starting and Switching Treatment

July 22, 2010
Reyataz/Isentress Combo Spares Norvir and Nukes, But Is Integrase Resistance a Concern?
Possibly No Survival Benefit to Starting HIV Treatment at CD4s of 500 or More
Once-Daily Prezista/Norvir Monotherapy Largely Effective Over 96 Weeks
Abacavir/Lamivudine Equivalent to Tenofovir/Emtricitabine in Canadian Cohort Study
July 19, 2010
Strategies for a Cure Reviewed in Vienna
Kaletra/Isentress Shows Promise as HIV Nuceleoside-Sparing Regimen for First-Line Treatment
Switch From Sustiva to Intelence Reduces Central Nervous System Side Effects
Protease Inhibitor-to-Isentress Switch is Effective, Lipid Friendly

Global HIV/AIDS

July 22, 2010
Health Care Providers and People With HIV Not Communicating Effectively
July 20, 2010
Tenofovir Microbicidal Gel Significantly Cuts HIV Infection Rate
5.2 Million People With HIV in Low- and Middle-Income Countries Now on Treatment
At Least 31 Countries Deporting People Living With HIV
HIV Cases in Young People Are Falling Around the World


[ about AIDSmeds | AIDSmeds advisory board | our staff | advertising policy | advertise/contact us]
© 2014 Smart + Strong. All Rights Reserved. Terms of use and Your privacy.
Smart + Strong® is a registered trademark of CDM Publishing, LLC.