HIV Therapy Dramatically Cuts Transmission in Heterosexual Pairs

"By Michael Smith, North American Correspondent, MedPage Today Published: May 12, 2011

Triple-drug therapy dramatically reduced transmission of HIV in heterosexual couples when one partner is infected and the other is not, results of a randomized trial showed.
Treating the infected partner in these discordant couples reduced transmission by 96%, compared with no treatment, according to Myron Cohen, MD, of the University of North Carolina Chapel Hill, and colleagues.
The $73 million trial had been slated to finish in 2015 but was stopped early after those clear-cut results were found by the study's data safety monitoring board during a planned interim review.
A series of mathematical models and observational studies have suggested that treatment of HIV can reduce transmission, and other studies have suggested that anti-HIV drugs might be used as prophylaxis.
But this is the "first, rather dramatic, randomized trial in discordant couples," according to Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, one of the sponsors of the so-called HPTN 052 trial.
It "nails the concept down rather nicely," he said in a telephone media conference.
Outside experts hailed the trial as a giant step forward.

"This study is another milestone in the history of HIV," said John Bartlett, MD, of Johns Hopkins. "The concept of treatment for prevention is proven."

"Patients can take the drugs for their own health and for public health," Bartlett added in an email to ABC News/MedPage Today.

The findings have the potential to transform approaches to the treatment and prevention of HIV," according to Mark Kline, MD, of Baylor College of Medicine in Houston.

Kline noted in an email to ABC News/MedPage Today that a trial in the mid-1990s showed that administering a single anti-HIV drug to pregnant women could prevent mother-to-child transmission of the virus.

That finding had "an immediate and direct impact on public health policies" and led many experts to think that treatment might prevent infection in other settings, he said.

"Now, we have conclusive evidence from a prospective, randomized treatment trial in support of that contention," Kline said.

Indeed, the findings "must serve as a clarion call" for expanded access to treatment, according to Mitchell Warren, executive director of the New York-based AIDS Vaccine Advocacy Coalition.
"We now have evidence from a randomized trial confirming what has been seen in observational settings: (antiretroviral) treatment is prevention," Warren told MedPage Today in an email.
The study, conducted by the HIV Prevention Trials Network, began in April 2005 and enrolled 1,763 couples, 97% of them heterosexual, in nine countries.
All the HIV-infected participants -- 890 men and 873 women -- had relatively intact immune systems, with CD4-positive T-cell counts between 350 and 550 per cubic millimeter and were not eligible at the time for HIV treatment based on their local guidelines.
They were randomly assigned to get immediate treatment or to wait until their CD4 counts fell to 250 or they had an AIDS-defining event.
All told, the review found 39 cases of HIV infection among the previously uninfected partners, and genetic analysis showed that 28 of those came from the infected partner. (Seven did not, and four are still being analyzed.)
But 27 of the linked infections occurred in the deferred treatment group and just one in the immediate therapy arm, a difference that was significant at P<0.0001.
All participants in the deferred treatment arm are now being offered triple-drug therapy regardless of their CD4 count, Cohen told reporters during the telephone media conference.
He said that the original plan for the study was to have homosexual couples included, but very few agreed to take part. For that reason, he said, it would be a "mistake" to assume this finding would apply to men who have sex with men.
Cohen added that the trial shows that even with a relatively intact immune system, transmission can occur. "You can't look at a high CD count and make the assumption that transmission is not going to occur," he said.
HIV transmission risk is linked to the amount of the virus in the blood, the so-called viral load, but many physicians will assume that if the CD4 count is relatively high, they can "let it go," Fauci said. The study investigators are currently analyzing viral load data from the trial, he said.
The treatment regimens used in the trial varied depending on the location of patients, Fauci said, with 11 different antiretroviral drugs employed in various combinations.
The researchers also found that 17 cases of extrapulmonary tuberculosis occurred in the HIV-infected partners in the deferred treatment arm and just three in the immediate treatment arm. The difference was significant at P=0.0013.
There were 23 deaths -- 10 in the immediate treatment group and 13 in the deferred treatment arm -- but the difference was not significant."


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