HIV Prevention :: The Lowdown on Current Microbicide Research
HIV infection rates have continued to rise for gay/bi and other MSM (men who have sex with men).
This has sparked interest in new prevention tools such as Treatment as Prevention for HIV-positive people and Biomedical HIV Prevention Strategies for HIV-negative people.
"Treatment as prevention, or TasP, involves using HIV medications to reduce the risk that an HIV-positive person will pass the virus to their sexual partner. Biomedical HIV Prevention Strategies focus on the use of antiretroviral medications (ARVs) by people who are HIV negative to reduce the risk of sexually transmitted HIV," said Dr. Ian McGowan, co-principal investigator of the Microbicide Trials Network.
Biomedical HIV Prevention Strategies include two methods of administration: Taking antiretrovirals orally (PrEP) and applying an antiretroviral gel rectally or vaginally (commonly known as microbicides). Current research investigates both these methods for safety and acceptability to the target population and frequency of administration (daily or per sexual encounter). In the last several months there have been some major developments in this area.
In April 2013, researchers at the Microbicide Trials Network (MTN) released the results of their study (named MTN-007) of 65 men and women. The results showed that a microbicide originally developed for vaginal use was safe for rectal use and was acceptable to the study participants. The gel was applied daily with high adherence (94 percent) and high reports of desire to continue using (87 percent). The microbicide contained an anti-retroviral, tenofovir, one of the active ingredients in the HIV medication Truvada.
Researchers are now in final stages of setting up a follow-up trial (named MTN-017). It will use the same microbicidal gel, but will be larger (186 men who have sex with men as well as transgender women) and more diverse, enrolling participants in Peru, South Africa, Thailand, and the U.S. (Pittsburgh, San Francisco, San Juan, and Boston). This study will contrast daily use of the microbicidal gel, episodic use (before and after sex) of the gel, and daily oral use of a pill using the same anti-retroviral as the gel.
In March 2013, researchers at the Microbicide Trials Network (MTN) stopped the VOICE (Vaginal and Oral Interventions to Control the Epidemic, MTN-03) study of PrEP and microbicides among women in Africa. One of the goals of the study was to test not just the drug, but also whether daily administration of a drug would be a feasible drug delivery schedule. High adherence to the daily dosing schedule would constitute high levels of acceptability. The study found that the women were not able to take either the oral medication or the microbicidal gel consistently on a daily basis.
(This study is not yet enrolling but if you're interested, visit mtnstopshiv.org.)
According to Dr. Sharon Hiller, co-principal investigator of the Microbicide Trials Network "effectiveness depends on use."
Researchers are not looking for the one magic bullet of HIV prevention, but rather different products to meet individual needs and preferences.
Hiller continued, discussing women's HIV prevention needs.
"Experience over decades of contraceptive development and use has shown that women's preferences differ, and that a product that best suits a women's lifestyle and needs is much more likely to be used," she said.
New products will be adopted more readily if they fit into already existing patterns. For women, that may be the pattern of contraceptive use. For gay and bi men, the similarities between the widespread use of lubes and a micriobicidal gel may make adoption of the gel relatively easy.
This menu of prevention products uses a market-based approach to HIV Prevention, but at present the costs of the product are unknown when presented to study participants. Unfortunately, cost is not a neutral fact in a market approach.
"From what we understand currently, the most costly aspect of tenofovir gel, for instance, is the packaging and the applicator - not the amount of drug in the gel, which is pretty low," said Jim Pickett, chair of the board of the International Rectal Microbicide Advocates (IRMA). "Clearly we are going to need to work on that aspect to make it affordable."
For more information about Microbicide Clinical Trials, visit mtnstopshiv.org.
For more information on IRMA, visit rectalmicrobicides.org.
Joining a Clinical Trial for Bio-medical HIV Prevention
Participating in a biomedical HIV prevention clinical trial is completely voluntary, but does require a commitment to using the product and honestly reporting experiences with it. All participants must be HIV-negative to participate. For more information, visit clinicaltrials.gov (trials within the U.S.) or mtnstopshiv.org (the U.S. and internationally).
IRMA and Rectal Microbicide Activism
The International Rectal Microbicide Advocates (rectalmicrobicides.org) is the only advocacy network in the world that focuses on the research and development of rectal microbicides. Joining the group simply requires being on its listserv. IRMA has lots of resources on its website that can help advocates get involved. IRMA recently developed a video, The Rectal Revolution is Here: An Introduction to Rectal Microbicide Clinical Trials. The video is available in English, Spanish, and Thai.
Developments in rectal microbicides have also spurred interest in lube safety. Very preliminary research indicates that some water based lubes may draw water out of cells and some other lubes may push water into cells. This transfer of water to and from cells in the rectal lining could lead to a loss of cellular integrity during the friction of sex, increasing the risk of HIV infection. While the preliminary evidence indicates that more research is needed, nothing is conclusive enough at this point to recommend any behavior change.
On June 12, 2013, over 500 individuals and organizations endorsed a Global Call to Action on Lubricant Safety. Jim Pickett of the International Rectal Microbicides Advocates reports that "The FDA has not required testing of any sexual lubricant - vaginal or rectal - except for some animal studies and condom-compatibility studies." For more information on lube safety, visit rectalmicrobicides.org.