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New ARTs Research Takes The Lead: HIV Microbicides Conference Report
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"It's going to be difficult to treat our way out of the epidemic," McGowan said. "We really need to improve prevention."
One key approach could be the use of substances known as microbicides, which the federally funded MTN has studied for several years. The substances are gels or creams that can be applied internally or externally to prevent HIV transmission.
Researchers try new ART approaches to preventing HIV
Mon May 24, Reuters
They also found evidence that using such an approach -- called a microbicide -- may help overcome some of the risks of drug resistance that can come with taking pills to prevent infection.
Here are some of the findings from the International Microbicides Conference being held in Pittsburgh:
* A flexible ring designed for use in the vagina can continually deliver two AIDS drugs for up to a month. Andrew Loxley of Bethlehem, Pennsylvania-based Particle Sciences, Inc., and colleagues lab tested a vaginal ring that time-released dapivirine, a drug made by Johnson & Johnson's Tibotec Inc and licensed to the International Partnership for Microbicides, and the entry inhibitor maraviroc sold by Pfizer under the brand name Selzentry. It has not been tested in people yet.
* A vaginal tablet worked in similar fashion, time-releasing maraviroc and another experimental HIV drug called DS003, licensed to the International Partnership for Microbicides by Bristol-Myers Squibb, Sanjay Garg of the University of Auckland in New Zealand told the conference. The tablet uses a polymer designed to attach to the moist lining inside the vagina.
* A third approach uses a film, Anthony Ham of ImQuest BioSciences of Frederick, Maryland reported. ImQuest is testing the HIV drug IQP-0528 in a film smaller and thinner than a stick of gum, similar to a mouthwash strip.
* Susan Schader of McGill University in Montreal, Canada, and colleagues said tests of these and other HIV drugs used as microbicides showed that drug resistance emerged only if HIV was in the lab dish first -- which suggests people would only develop drug-resistant infections by using microbicides when they were already infected.
* The AIDS virus infects more than 33 million people globally and it has killed 25 million, according to the United Nations AIDS agency UNAIDS. Globally, more than half of those with HIV are women, most infected by husbands or steady partners and many of whom who are unable to insist on use of a condom.
* AIDS experts have long been searching for a microbicide -- a cream, gel or vaginal ring that women or men could use as a chemical shield to protect themselves from sexual transmission of the deadly and incurable virus.
* Microbicides using HIV drugs would represent a large new market for the companies that make the drugs, which are now used only to treat infection.
http://globalhealth.kff.org
Researchers on Monday at the International Microbicides Conference (M2010) in Pittsburgh continued to present data on HIV prevention research, Reuters reports (see their report above). The news service outlines several prevention methods being researched, including an intravaginal ring that over time releases two antiretrovirals (ARVs) - dapivirine and maraviroc - for up to a month, and a vaginal tablet that time-releases the antiretrovirals dapivirine and DS003 for up to 12 hours. Both methods have yet to reach clinical trials.
Reuters also notes that researchers have formulated a vaginal film containing the ARV compound IQP-0528 that is currently undergoing laboratory tests (Fox, 5/24). Full descriptions of the data presented on these techniques for protecting women from HIV transmission is available in an M2010 press release (.pdf) (5/23).
Times Live's "Tracking HIV" blog reports on discussion at the conference about Pre-Exposure Prophylaxis (PrEP), where HIV-negative patients take ARVs as a method of prevention. In order to avoid an increase in ARV drug resistance, researchers warned Monday during the M2010 conference that anyone taking PrEP must first know his or her HIV status, "Tracking HIV" reports.
The University of Pittsburgh's John Mellors "expressed concern at the 'substantial overlap in the drugs being used for treatment and those being studied for prevention.' He said in a worst case scenario widespread resistance at a population level to these drugs could end up rendering them ineffective for both treatment and prevention. But he added: 'It is very rare to become infected with a virus we can't treat today,'" the blog reports (Keeton, 5/24).
A press release (.pdf) from M2010 details the results of two studies presented at the conference that examine how using ARVs for prevention could contribute to drug resistance.
For one of the two studies presented, Ume Abbas of the Cleveland Clinic Foundation helped lead a team of researchers in the development of a mathematical model "to simulate the impact of PrEP on HIV prevention and drug resistance in a region of sub-Saharan Africa, where HIV rates are among the highest, and to identify the determinants contributing most to HIV drug resistance prevalence," according to the press release. "The model singled out two factors having the most influence, finding that the greater number of people who use PrEP who shouldn't be and the longer they keep using the ARVs, the more prevalent drug resistance would be," according to the press release.
The press release describes a second laboratory study where researchers "infected blood cells with different subtypes of HIV and exposed the infected cells to dapivirine alone and to dapivirine plus tenofovir continuously for more than 25 weeks to induce drug resistance" to test whether ARV-based microbicide compounds could cause the virus to become resistant. " Drug resistance emerged only if HIV infection was present before the candidate microbicide ARVs were introduced and continued to be used," according to the release (5/23).
Aidsmap | Six existing drug classes now being tested as microbicides
May 23, 2010 ... A number of presentations at the 2010 International Microbicides Conference in Pittsburgh concerned microbicide research using established ...
www.aidsmap.com/.../61B8836B-7A08-4EF7-90EB-939FB828DAA0.asp
Monday, May 24, 2010
A study in Africa, presented Sunday at the International Microbicides Conference (M2010) in Pittsburgh, has shown that a man's risk of HIV infection doubles if his HIV-positive partner is pregnant, according to HealthDay News/U.S. News & World Report.
"The two-year study - launched in Botswana, Kenya, Rwanda, South Africa, Tanzania, Uganda and Zambia - focused on more than 3,300 couples in which one of the partners was HIV-positive," the news service writes. "During the duration of the study, 823 pregnancies occurred. The study authors found that pregnancy increased HIV transmission in both directions: male-to-female and female-to-male" (5/23).
Though "the observed infection risk for women appeared to be a function of several factors beyond pregnancy itself, including sexual behavior," the researchers noted "[f]or men, the link between pregnancy and risk increase was much stronger and more direct," according to a press release (.pdf) from M2010 (5/23).
The Independent writes the "study concluded 'pregnancy was associated with increased risk of both female-to-male and male-to-female HIV transmission' and '...the link between pregnancy and HIV risk was much clearer (in men), even after considering whether or not they had engaged in unprotected sex or were circumcised. Measures of viral load and CD4 counts of the infected partner also had no bearing.'"
Nelly Mugo of the University of Nairobi/Kenyatta National Hospital (KNH) and University of Washington, who lead the study and presented it on behalf of the Partners in Prevention HSV/HIV Transmission Study said that "pregnant female-to-male transmission is something that needs greater attention as 'biological changes that occur during pregnancy may make women more infectious than they would be otherwise,'" the newspaper writes (5/23).
In other news, a study examining the safety of microbicidal gel use during pregnancy was also presented Sunday at the conference, the BBC reports (5/23).
"Results of the first study of a vaginal microbicide tested in pregnant women found only small amounts of drug are absorbed into the bloodstream, amniotic fluid and umbilical cord blood," according to the M2010 press release. "The study, which involved applying a single dose of tenofovir gel hours before women gave birth by cesarean delivery, was conducted as a first step toward determining if use of a vaginal microbicide during pregnancy is safe for women and their babies" (5/23).
The Standard reports on the participation of Zimbabwean researchers at M2010, and highlights how a collaboration between the University of Zimbabwe and the University of California, San Francisco, backed by the U.S. National Institutes of Health, is studying ways to improve methods to prevent the spread of HIV to women (5/22).
Also reporting on M2010, the Pittsburgh Tribune-Review examines the recent studies of microbicides as a method to drive down the spread of HIV. "Despite setbacks with the first generation of microbicides, newer versions contain the same antiretroviral drugs used to treat HIV. Results of a small study in South Africa, involving 1,000 women, will be released this summer," the newspaper writes. The Microbicide Trials Network, which is hosting M2010, "last year began a large-scale clinical trial to test microbicides that contain antiretroviral drugs. The trial is expected to enroll 5,000 women in Uganda, South Africa, Zambia and Zimbabwe," the newspaper adds.
The article includes comments from Ian McGowan, a leading investigator at Microbicide Trials Network, and Jim Pickett, director of advocacy for the AIDS Foundation of Chicago, who will speak at the conference (Fabregas, 5/21).
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