A First for Women, New Life for Microbicides
07/20/2010
FHI's Ward Cates on the exciting results of the CAPRISA 004 microbicide trial
The exciting results of the CAPRISA 004 trial released today in Vienna are a hopeful and promising first step towards giving women a new tool to protect themselves from HIV infection. This is the first time that a microbicide trial has shown a significant decrease in the rate of HIV acquisition, with 39 percent fewer infections. Additionally, among women who were the most adherent to the trial regimen, we saw an even greater rate of protection - up to 54 percent. These findings alone are reason for hope, but the trial also presented some other important "firsts."
This is the first microbicide to be shown effective in preventing herpes acquisition. Women using the gel showed a 51 percent decrease in new herpes infections. Up to a quarter of sexually active adults are estimated to carry the genital herpes virus. Women who have herpes are also significantly more likely to acquire HIV than those who do not.
This is the first effectiveness study of an antiretroviral (ARV)-based topical microbicide gel. The ARV used in the trial is tenofovir, a drug that prevents HIV from replicating inside cells. The drug is approved for HIV treatment. This trial, therefore, uses a proven technology (tenofovir) in a novel way, opening up the potential for an entirely new class of drugs. The gel, applied vaginally, also acts as a sexual lubricant - a side effect that many trial participants and their partners not only found acceptable, but pleasurable.
This microbicide research was lead by a South African institution, a global first. This exemplifies the Global Health Initiative principles: country ownership with scientific collaboration among global partners. The USIAD-funded trial and the partnership that conducted it - CAPRISA, FHI and CONRAD - has set an extremely high bar both scientifically and operationally for research institutions around the world. For example, CAPRISA 004 achieved a 95 percent retention rate which is extraordinary.
An ARV-based microbicide gel advances the opportunity for women to protect themselves in circumstances where they are unable to negotiate condom use (male or female) with a partner. This is crucial since more than half of new HIV infections in Africa are in women.
These results are promising in our worldwide effort to turn around the HIV epidemic - the most encouraging since male circumcision was established as an effective HIV prevention method several years ago. However, we must remember that this is only one trial. Three separate reinforcing studies were necessary to provide sufficient evidence for male circumcision. Further studies must be conducted to validate effectiveness, establish dosage, determine long-term safety, assess impact on sexual behavior and evaluate any effect on HIV drug resistance. This necessary verification process should not, however, dampen the excitement. The awesome potential of this new prevention tool cannot be overestimated.
Ward Cates, MD, MPH is president, research, at FHI.
Promising new prevention tool that women can use without having to negotiate with their male partner.
Sds,
Pascoal
— SE Embaixadora L. Mate on 2010-07-21
Like everyone else, I’m hopeful that the initial CAPRISA findings will be confirmed in expanded trials. But the overall effectiveness of Tenofovir in the CAPRISA data isn’t all that great - only a 39% gain in HIV infection prevention among women using for longer periods. That simply isn’t good enough, especially if women get the idea that the new gel gives them greater protection than it actually does and other preventive measures (like condoms) are more readily unused. I could get excited about a microbicide that blocks HIV transmission 80-90% of the time, but not 39%. That just isn’t adequate - would we be getting excited about a new contraceptive that only afforded women a 39% greater chance of not becoming pregnant? I think the euphoria that’s greating the new CAPRISA trial results is a little over-the-top, and potentially even dangerous.
— Andrew Kantner on 2010-07-21
While 39% effectiveness in this trial may not be great, it would very likely be much more effective in the real world. The control group in this trial received counseling about risk reduction and condoms, thereby lowering the demonstrated effectiveness of the intervention. If the subject participants had been compared to a control group with a placebo and no condoms, effectiveness would undoubtedly have been much higher. This is a common issue facing randomized control trials. They can fail to discover the true impact of a valuable intervention due to ethical review board requirements to provide some measure of protection to all study participants, including the control group.
— Ed Scholl on 2010-07-23
It is encouraging for it takes mankind closer to discovering a ‘solution’ to the HIV challenge.
— Pamela N. on 2010-07-23
I understand this gel has been either approved for use in Zimbabwe or is under study there. whatever the case maybe I hope this is being delivered carefully to avoid mistakes due to poor teaching/health information on how to use it and what to expect both negatives and positives for all users in that country and not using them just as (study subjects)resulting in unchecked negatives to its use,just to be polite.
— gladys mundowa/makayi on 2010-07-27
I agree that Tenofovir partial success, provides hope for pervention of HIV by
Microbicides. I would suggest to build on this partial success to reach the level of 80%- 90%,by using the new cervical barrier that is approved by FDA for prevention of pregnancy. The FemCap is designed with a unique delivery system ( a resrvoir )facing the vaginal opening.This resrvoir can hold the microbicide for 48 hours and thus eliminate the frequent use of the applicator and thus enhance adherence.
— Alfred Shihata, MD on 2010-08-01