By Michael Smith, North American Correspondent, MedPage Today
Published: July 13, 2011
Published: July 13, 2011
Daily prophylaxis with anti-HIV drugs significantly reduces the risk of catching the virus for heterosexuals, according to investigators on two large trials in Africa.
The findings extend a similar result among men who have sex with men and were hailed as a "major milestone" by a senior CDC official.
"Heterosexuals are hardest hit by HIV/AIDS worldwide, and these studies give us the first strong, compelling evidence that (pre-exposure prophylaxis) can work in this population," according to Kevin Fenton, MD, PhD, director of the agency's National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention.
"This is an extremely exciting day for HIV prevention," Fenton told reporters in a telephone press conference to discuss the two studies.
In the so-called Partners PrEP trial in Kenya and Uganda, daily prophylaxis reduced the risk of acquiring HIV by between 62% and 73% in uninfected partners of men and women with the virus, according to Jared Baeten, MD, PhD, of the University of Washington in Seattle, who was the study's principal investigator.
In the light of those results, the study's data safety monitoring board recommended that the placebo arm of the trial be stopped, Baeten said.
In response, the CDC released data from the so-called TDF2 study, conducted in Botswana, showing approximately a 63% reduction in the risk of acquiring the virus among heterosexual men and women taking a two-drug combination pill.
The reports come after a landmark study in the field of so-called pre-exposure prophylaxis, or PrEP – the iPrex study in HIV-negative men who have sex with men -- showed that daily medication could reduce the risk of catching HIV by 44%.
In the Partners PrEP trial, investigators enrolled 4,758 HIV serodiscordant couples and randomly assigned the uninfected partners to placebo or one of two drug arms -- daily tenofovir (Viread) or daily tenofovir combined with emtricitabine (sold as Truvada).
The study's data monitoring board found that, up to May 31, 78 participants acquired HIV -- 18 of those taking tenofovir, 13 of those assigned to tenofovir/emtricitabine, and 47 of those getting placebo, according to Baeten.
In other words, Baeten said, those taking tenofovir had an average of 62% fewer HIV infections, which was significant at P=0.0003, and those taking the combination had 73% fewer HIV infections, which was significant at P<0.0001.
PrEP reduced HIV risk in both women and men, he said.
Although the placebo arm has been halted, Baeten said, the study is continuing to look at whether tenofovir monotherapy or the drug combination is better.
The TDF2 trial in Botswana had a slightly different design; it enrolled 1,200 men and women who were HIV-negative (but not necessarily in a discordant couple) and randomly assigned them to take daily tenofovir/emtricitabine or placebo, according to Michael Thigpen, MD, of the CDC, who was the study's principal investigator.
Among the 601 participants who got the study drug, nine became infected with HIV, compared with 24 among the 599 individuals taking placebo, Thigpen said.
The risk reduction was 62.6%, which was "strongly statistically significant," Thigpen told reporters.
He added that investigators didn't find any significant safety concerns associated with daily prophylaxis, and there were no cases of drug resistance.
"The results of this trial provide strong evidence that pre-exposure prophylaxis is safe and effective in preventing HIV infection among heterosexuals," Thigpen said.
A related result has shown that treating HIV – even when it is not clinically indicated – can dramatically reduce the risk of transmitting the virus in heterosexual couples in which one partner is not infected.
The HPTN 052 study, in discordant heterosexual couples, treated the infected partner early with full-scale triple drug therapy and found the risk to the uninfected partner was reduced by 96%.
"These results are tremendously exciting and confirm that we are at a pivotal period in the AIDS epidemic," according to Mitchell Warren of the New York-based prevention advocacy group AVAC.
"Antiretroviral drugs for HIV treatment began to turn the tide of the epidemic 15 years ago, and it is clear that also using (antiretrovirals) for HIV prevention will strengthen our response to AIDS," Warren said in a statement.
Despite the positive results, the CDC is urging people to wait before adopting the approach, according to Jonathan Mermin, MD, director of the CDC's Division of HIV/AIDS Prevention.
The agency will "fully review" the trials to develop public health guidance for PrEP, Mermin said.
"At this time we urge heterosexual men and women and their healthcare providers to await CDC guidance before considering PrEP for HIV prevention," Mermin said.
If people can't wait, he added, they should follow CDC guidance on PrEP for men who have sex with men, which suggested the tenofovir/emtricitabine combination, rather than tenofovir alone.
Mermin added the findings are "a breakthrough in prevention because it's an additional mechanism" to tackle the HIV epidemic. "Up to this point, we have not had a drug that would prevent acquisition of HIV among uninfected people," he said.
AHP: Berita ini sepatutnya menambahkan keyakinan dan nilai positif kepada semua pembawa HIV khususnya kepada yang telah berkahwin dan bimbang mendapatkan rawatan. Terima kasih & Jazakallah Khier kepada As, salah seorang sahabat yang tak jemu-jemu beri sokongan dan berkongsi maklumat.