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HIV drugs found to aid prevention

Hub researchers help lead study

A study found that men taking Gilead Sciences’ Truvada were less likely to contract HIV. A study found that men taking Gilead Sciences’ Truvada were less likely to contract HIV. (Justin Sullivan/ Getty Images)
By Elizabeth Cooney
Globe Correspondent / November 24, 2010

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Researchers reported yesterday that the same drugs that have transformed HIV infection from a death sentence into a chronic disease can also help protect gay men from being infected with the virus in the first place — a finding hailed by specialists as a major advance in stopping the spread of AIDS.

A study conducted in Boston and 10 other sites worldwide found that among men at high risk for contracting the AIDS-causing virus, those randomly assigned to take a daily antiretroviral pill were 44 percent less likely to become infected than those receiving a dummy pill. The infection risk was even more dramatically reduced among men who faithfully took the pills.

AIDS specialists said the discovery gives them a powerful new tool — a drug that is already widely available and can be quickly used to slow a disease that, worldwide, infects 7,000 more people each day.

“This is proof of [the] concept that one can decrease one’s risk of being HIV-infected by taking medications before exposure,’’ Dr. Kenneth Mayer of The Fenway Institute in Boston and Brown University and one of the researchers, said in an interview.

The idea of giving people drugs to prevent infections is not new. Antimalaria pills, for example, are commonly prescribed for that purpose. And babies born to HIV-infected mothers are given drugs to keep them healthy. But the new study, published online yesterday in the New England Journal of Medicine, is the first to test the effectiveness of oral medications to prevent HIV infection before exposure.

Dr. Paul Sax, clinical director of the HIV program and division of infectious disease at Brigham and Women’s Hospital, said it’s a “very, very important study’’ in a year of notable work in the HIV field, following hopeful signals about an HIV vaccine and a South African trial that showed a vaginal microbicide gel cut women’s risk of infection nearly in half.

Sax, who was not involved in the new study, cautioned that the reduction in risk might be smaller in the real world, as often happens when translating results from research volunteers into everyday life. And he noted that the safety of a medication takes on even more importance when it’s being used by healthy people.

“The bar has to be set a bit higher when preventing infection rather than treating it,’’ he said.

Still, he said, the discovery announced yesterday “was a significant result.’’

Some men who took the medication did have side effects, such as high levels of a protein linked to kidney problems. Others experienced nausea at first. Long-term use of the drugs could lead to other complications, including the development of drug-resistant strains of HIV.

The next step for researchers is to establish the smallest amount of the drug needed for the maximum benefit, Mayer said.

Researchers in six countries recruited 2,499 HIV-negative men who have sex with men, including 87 in Boston. They were at high risk of HIV infection because they had many sexual partners or often had unprotected sex. Half the men were randomly assigned to take Gilead Sciences’ Truvada pill daily, a combination of emtricitabine and tenofovir, and half, a placebo. All the participants also received counseling, condoms, HIV-testing, and management of other sexually transmitted diseases when they came for their monthly supply of pills.

After an average of one year, 100 men tested positive for HIV. Thirty-six were taking the antiretroviral drugs and 64 were taking the placebo, amounting to a 44 percent reduction in HIV risk among the antiviral group.

The men who most consistently took the medication, as shown by blood levels of the drug, were even less likely to be infected. Their risk was reduced by more than 90 percent. Half of the men without infections had detectable levels of the drug in their blood but only 10 percent of the infected men in the antiretroviral group did. “Pills won’t help you if they’re still in the bottle,’’ Mayer said. “Adherence is going to be really important.’’

Researchers had feared the pills might give a false sense of security and make men less likely to use condoms or to limit their partners, but the opposite happened — risky sex declined.

The results are “a major advance’’ that can help curb the epidemic in gay men, said Dr. Kevin Fenton, AIDS prevention chief at the US Centers for Disease Control and Prevention. But he warned they may not apply to people exposed to HIV through male-female sex, drug use, or other ways. Studies in those groups are under way now.

The news came as UNAIDS announced that the global epidemic was slowing — new cases dropped nearly 20 percent over the last decade and about 33 million people are living with HIV now. Health officials credit part of the decline to wider condom use.

Because Truvada is already on the market, the CDC is rushing to develop guidelines for doctors using it for HIV prevention, and urged people to wait until those are ready.

“It’s not time for gay and bisexual men to throw out their condoms,’’ Fenton said. The pill “should never be seen as a first line of defense against HIV.’’

As a practical matter, price could limit use. The pills cost up to $14,000 a year in the United States, but only 39 cents a day in some poor countries where they are sold in generic form.

Whether insurers or government health programs should pay for them is one of the tough issues to be sorted out, and cost-effectiveness analyses should help, said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

“This is an exciting finding,’’ but it “is only one study in one specific study population,’’ so its impact on others is unknown, Fauci said.

His institute sponsored the study with the Bill & Melinda Gates Foundation. The Gladstone Institutes of the University of California, San Francisco coordinated the research.

Material from the Associated Press was used in this report. Elizabeth Cooney can be reached at ecooney@globe.com.

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