Once-a-Day AIDS Prevention Pill Gives New Hope
A major study shows for the first time that a drug duo widely used to treat the AIDS virus can block HIV infection, researchers said Tuesday.
The drugs tenofovir and emtricitabine, packaged as a once-daily pill and sold in drugstores as Truvada, reduced HIV infections by an average of 44% among gay and bisexual men who took the drug, compared with those taking a placebo. Men who reported being the most diligent about taking their pill each day reaped an even bigger benefit, reducing their risk by 73%.
"This is a huge step forward," says lead researcher Robert Grant, at the J. David Gladstone Institute at the University of California-San Francisco, a non-profit research foundation that carried out the study.
David Paltiel of Yale University says that his research shows that Truvada could be as cost-effective a prevention method as those used to combat heart disease diabetes and cancer, despite its $8,700 annual cost.
The findings have bred new enthusiasm in a field where, for years, optimism was rare. Over 30 years, HIV has infected 40 million people. But this year alone, researchers have demonstrated that a pill and a vaginal gel (containing a component of Truvada) can prevent HIV and shown, at least in concept, that a vaccine can work.
"This is a very exciting, dynamic time in HIV prevention research," says Alan Bernstein, head of the Global HIV Vaccine Enterprise, a non-profit effort to accelerate vaccine research. "It couldn't come at a better time. There's clearly a growing realization that we're not going to be able to treat our way out of this epidemic.
Even with support from the Global Fund for AIDS, Tuberculosis and Malaria and the U.S. President's Emergency Plan for AIDS Relief, only about a third of people with HIV worldwide get treatment, Bernstein says.
Over the next two or three years, researchers hope to determine whether Truvada also works in heterosexuals and drug users and whether it can prevent infection if taken intermittently, hours before having sex.
Federal health officials cautioned that the jury is still out on whether the drug works in groups other than gay and bisexual men, adding that they've just begun analyzing the findings from today's study so they can craft prevention guidelines and put the approach to work in "real world" settings.
"It's no time for gay and bisexual men to throw away their condoms or abandon other ways to prevent HIV," says Kevin Fenton, director of HIV prevention at the Centers for Disease Control and Prevention.
The HIV epidemic is still growing among gay and bisexual men, Fenton says, who now account for more than half of roughly 60,000 new HIV infections that occur nationwide each year. Gay and bisexual men are 44 times more likely to get HIV than other men, CDC statistics show.
A string of failures in HIV-prevention research — of 37 trials, only 6 have been successful, three of them involving male circumcision — prompted researchers to try to determine whether drugs capable of stopping HIV from multiplying could prevent infection, Grant says.
Truvada was chosen because it is highly effective, has relatively few side effects and is less likely to promote HIV resistance than other drugs. Since its approval in 2004, Truvada has become the world's top selling AIDS drug, with more than $2 billion in sales last year, according to IMS Health, a medical information company.
The new study involved 2,499 men and transgendered women in six countries, including the USA, who have sex with men. The participants were divided into two groups; half were given Truvada and half received a placebo, the researchers report online today in the New England Journal of Medicine. All of the volunteers were advised to use condoms and take other precautions to avoid getting sexually transmitted diseases.
"Everyone was told not to rely on this pill, because they might be getting a placebo," Grant says.
After slightly more than a year of treatment, 36 people who were getting Truvada became infected with HIV, compared with 64 infections among those getting a placebo.
An analysis of 34 of the 36 people in the Truvada group who got HIV found that they had very little of the drug in their blood or none at all, suggesting they weren't taking the drug as prescribed.
Those with measurable amounts of Truvada in their blood had 13-fold greater protection from infection, says Anthony Fauci, of the National Institute of Allergy and Infectious Diseases, which sponsored the study.
"That translates into more than a 90% reduction in risk," Fauci says.
Fauci cautioned that HIV is far too widespread to yield to one new prevention approach.
Paltiel agreed. "This drug alone," he says, "isn't going to stop this epidemic,"
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