Men who faithfully take a daily pill that contains drugs to treat HIV can reduce their risk of catching the deadly virus by up to 73 percent, the National Institutes of Health said in a study released Tuesday.
Researchers cautioned, however, that Truvada, an anti-retroviral drug now used by people already infected with HIV, achieves such stunning success only when taken diligently and used in combination with other prevention strategies.
Nevertheless, such eye-popping results, published Tuesday in the New England Journal of Medicine, produced applause from gay-rights and AIDS-activist groups and from the White House.
“I am encouraged by this announcement of groundbreaking research on HIV prevention,” President Obama said after the NIH study findings were announced. “While more work is needed, these kinds of studies could mark the beginning of a new era in HIV prevention.”
“These results represent a major advance in HIV prevention research,” said Dr. Kevin Fenton, director of the Centers for Disease Control and Prevention’s (CDC) National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention.
“For the first time, we have evidence that a daily pill used to treat HIV is partially effective for preventing HIV among gay and bisexual men at high risk for infection, when combined with other prevention strategies,” Dr. Fenton said. This is “exciting and welcome news.”
The approach is called “pre-exposure prophylaxis,” or PREP.
In the NIH study, led by Dr. Robert M. Grant, some 2,500 homosexual or bisexual men, all of whom were HIV-negative, participated in six countries from July 2007 through 2009.
The men were given pills to take daily without knowing whether it was Truvada or a placebo. They were then checked regularly for HIV status, and assessed on how well they adhered to safe-sex strategies and pill regimen.
Some 110 of the men acquired HIV — 64 were taking placebo pills, and 36 were taking Truvada.
Based on this outcome, researchers said, the men who faithfully took the Truvada pills on 90 percent or more days lowered their risk of getting HIV by about 73 percent. In general, the risk reduction for all men was about 44 percent. According to the CDC, though, that the HIV risk for the least-compliant group of men declined by only 21 percent.
Taking the drug also doesn’t seem to encourage risky behavior in response. The NIH study also found that after the men started the study, their risky sexual behavior “decreased substantially” and “remained lower” than usual during the drug trial.
Dr. Fenton cautioned that these results were only for Truvada use in a male homosexual and bisexual populations. There are no data regarding Truvada’s ability to prevent AIDS among heterosexuals, women or intravenous drug users, he said.
It also was effective only with men who were confirmed HIV-negative and who practiced additional prevention strategies such as consistently using condoms, getting treatment for other sexually transmitted diseases and reducing the number of sex partners.
The hope is that high-risk populations — men who have sex with men (MSM) and bisexual men — will use an HIV-prevention pill. Surveys indicate that “the majority” of men in these groups would consider using such a product if it was proved to be safe and effective, the NIH study said.
According to the CDC, an estimated 56,000 people acquire HIV each year, and more than half of them are gay or bisexual men. The rate of new HIV diagnoses among MSM is more than 44 times that of other men, the agency added.
The NIH study offers “great hope” about biomedical interventions, said Marjorie J. Hill, chief executive of Gay Men’s Health Crisis.
“We support further research to develop effective biomedical prevention interventions, even as we spread the word about what works best now,” she said, adding that “by far, the most effective prevention technologies remain condoms and lubricant, and clean needles.”
Ernest Hopkins, legislative director at the San Francisco AIDS Foundation, told AIDS.gov video this past summer that the PREP approach is “a promising tool,” but he wondered who will pay for it and how will the MSM community be taught about it.
“Much more needs to be understood before PREP is rolled out to the community, but for now, this study presents an encouraging glimmer of hope, particularly in San Francisco,” since this is where the HIV/AIDS epidemic began, the foundation said yesterday.
According to the annual HIV drug guide put out by Test Positive Aware Network, a month’s treatment of Truvada cost $868 in 2006.
The study was supported by the National Institute of Allergy and Infectious Diseases’ Division of Acquired Immunodeficiency Syndrome at NIH; the Bill and Melinda Gates Foundation; and Gilead Sciences Inc., which makes Truvada. Dr. Grant is with the J. David Gladstone Institutes, a private foundation affiliated with the University of California in San Francisco.
The six countries that participated in the study are Peru, Ecuador, South Africa, Brazil, Thailand and the United States.