麻豆果冻传媒影音

ROME -- Men who took a daily anti-HIV pill reduced their risk of acquiring HIV from sex with other men by more than 90%, a researcher said here.

And overall in a placebo-controlled randomized trial, taking non-adherence into account, the single-pill combination of two antiretroviral drugs reduced the risk of acquiring the virus by 42% on top of other protective measures, according to Robert Grant, MD, of the University of California San Francisco.

The findings come from the final analysis of the landmark iPrEx study, the first to show that so-called pre-exposure prophylaxis, or PrEP, could work in people, Grant told a late-breaker session at the 2011 meeting of the International AIDS Society.

Two other studies -- dubbed TDF2 and Partners-PrEP -- were presented here and have extended the results to heterosexuals.

The iPrEx study enrolled 2,499 men who have sex with men in 11 sites on four continents and randomly assigned them to daily placebo or a pill containing tenofovir and emtricitabine (Truvada).

As in all such trials, they also had access to a package of other interventions, including HIV counseling and free condoms, Grant said.

The primary endpoint was the proportion of people in each arm who acquired HIV during the 144 weeks of follow-up, Grant said.

In a modified intention to treat analysis, Grant said, a difference between the arms appeared early and increased over the course of the study.

All told, there were 83 infections in the placebo arm and 48 among those getting the drugs, yielding an efficacy rate of 42%, which was significant at P=0.002.

The study medication averted 35 new cases of HIV, Grant said.

On the other hand, a sub-analysis, adjusted for age, schooling, body mass index, and unprotected receptive anal intercourse, showed that only 10% of the 48 people who acquired HIV had detectable drug in their blood around the time when they were infected, Grant said.

Among 144 seronegative controls, who were matched for site and time on study, the rate was 44%.

Grant said the risk reduction associated with having detectable drug in the blood was 92%.

There was little difference in outcome among subgroups in the study, with the exception of those who reported unprotected receptive anal intercourse, Grant said.

Efficacy in that group -- thought to be at increased risk of HIV -- was significantly higher, at P=0.03, than among those who did not report the activity, Grant reported.

The researchers found no indication that being on the trial increased rates of risky behavior even among people who thought they were getting the study drug.

There were also no signs of drug resistance among those who eventually acquired HIV, Grant said.

The study has already led to a CDC interim guidance for men who have sex with men, according to Chris Beyrer, MD, of Johns Hopkins University in Baltimore.

Now, he told MedPage Today, the CDC is going to have to rework that to include data on heterosexuals. "When you have multiple studies," he said, "your guidance needs to reflect that."

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