July 13, 2011 — In another major advance against the spread of HIV/AIDS, 2 studies released today report that a daily dose of antiretroviral drugs used to treat HIV infection also can reduce the spread of the virus among heterosexuals.
Last fall, a similar study found that administering antiretroviral drugs in an approach called preexposure chemoprophylaxis (PrEP) reduced HIV infections among men who have sex with men. And in a study halted this spring, starting patients with HIV on oral antiretroviral therapy immediately after diagnosis, while their immune systems are still relatively healthy, was shown to be highly effective in protecting their partners from infection.
The latest studies represent a major development because heterosexuals are the population hardest hit by HIV worldwide, according the US Centers for Disease Control and Prevention.
At a press conference today, CDC officials used words like "game changer" and "breakthrough" to describe the new PrEP findings, but cautioned that this therapy alone is not the solution to HIV/AIDS. HIV testing, condom use, and other preventive measures remain indispensable, they said.
"[PrEP] is an additional tool, and combined with other methods, it may help us reverse the epidemic," said Jonathan Mermin, MD, director of the CDC's Division of HIV/AIDS Prevention.
In one of the new studies, sponsored by the US Centers for Disease Control and Prevention and conducted in partnership with the Botswana Ministry of Health, roughly 1200 HIV-negative heterosexual men and women took either a daily dose of tenofovir disoproxil fumarate and emtricitabine (Truvada, Gilead Sciences) or a placebo. The PrEP regimen reduced the risk of acquiring HIV by 63%.
The other study, led by the International Clinical Research Center at the University of Washington, Seattle, found that daily PrEP reduced HIV transmission among approximately 4800 heterosexual serodiscordant couples in Kenya and Uganda. Uninfected partners received the combination of tenofovir and emtricitabine, tenofovir (Viread, Gilead Sciences) alone, or a placebo. The infected partners did not meet immunological criteria set by Kenya and Uganda to qualify for antiretroviral therapy.
Those patients who received tenofovir alone had an average of 62% fewer HIV infections than the placebo group, according to preliminary study results. The risk reduction was even higher for the group receiving the combination of tenofovir and emtricitabine, at 73%. Because of the efficacy of the PrEP approach, an independent group of advisors monitoring the study recommended discontinuing the placebo group of the study and releasing the preliminary data.
Combine PrEP With Other Prevention Methods, Says CDC
CDC officials promised that their agency would develop guidance on the use of PrEP by heterosexual men and women in this country and urged such individuals and their healthcare providers to wait for this advice before beginning treatments. However, if clinicians decide that their patients have an urgent need for PrEP, they should follow the guidelines that the CDC issued for its use in men who have sex with men. PrEP, the agency cautions, must be confined to individuals who test negative for HIV infection, and it must be combined with other prevention methods such as using a condom.
The study establishing the efficacy of PrEP for men having sex with men, the CDC notes, looked only at the combination of tenofovir and emtricitabine. There are no data on the prophylactic effectiveness of tenofovir alone.
Tenofovir/emtricitabine and tenofovir alone are FDA-approved to treat HIV-1 infection. They are not approved for PrEP, but clinicians can prescribe them on an off-label basis.
Several reporters at today's press conference asked CDC officials where the money would come from to pay for antiretrovirals used prophylacticly on a widespread basis in the United States. Kevin Fenton, MD, PhD, the director of the CDC's National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, replied that even in challenging economic times, the nation needs to keep investing not only in HIV/AIDS research, but also in prevention programs.
"These [new] studies underscore the importance of the investments we're making," Dr. Fenton said.
More information about the PrEP study findings released today is available on the CDC Web site.
Эх сурвалж:
PrEP Reduces HIV Infections Among Heterosexuals
