Daily oral antiretroviral reduces HIV infection risk in MSM by 44%, study finds

Nov 24 2010

A study that included nearly 2,500 HIV-negative men and transgender women who have sex with men has shown that a daily dose of Truvada, a pill containing the AIDS drugs emtricitabine and tenofovir, "can reduce risk of contracting [HIV] by an average of 44% - and by more than 70% if the subjects" follow the regimen closely, Los Angeles Times reports (Maugh, 11/23). 

The iPrEx HIV Prevention Study, which was carried out by researchers at the J. David Gladstone Institute, a non-profit in California, and published Tuesday in the New England Journal of Medicine, involved "2,499 men, including 29 transgendered women, between the ages of 18 and 67 who were sexually active with other men but were not infected with the virus that causes AIDS," Agence France-Presse writes. The study ran "from July 2007 to December 2009 in six countries - Brazil, Ecuador, Peru, South Africa, Thailand and the United States" to test the efficacy of "taking a drug ahead of potential exposure to HIV … called pre-exposure prophylaxis (PrEP)," AFP reports (11/23).

"The trial cost about $43.6 million, of which National Institute of Allergy and Infectious Diseases (NIAID) contributed $27.8 million and the Bill & Melinda Gates Foundation paid $15.7 million. Gilead donated the drugs used in the trial and paid travel costs for some of the researchers," Bloomberg reports (Bennett, 11/23).

Study participants were randomly selected to either receive Truvada or a placebo pill, according to a NIAID-NIH press release. Over an average of 14 months, participants received monthly HIV infection evaluations. "In addition, all participants were routinely counseled about safe sex practices and provided condoms and treatment for other sexually transmitted infections," the press release states (11/23).

"Among the group taking Truvada, which is used to treat people who are HIV-positive, 36 men contracted HIV, compared with 64 men in the placebo group - amounting to a 44 percent reduction in cases," the San Francisco Chronicle reports. "The drug was meant to be taken daily, but men in both groups often skipped doses. Among men who took the drug at least 90 percent of the time, the group taking Truvada had [72.8] percent fewer cases of HIV infection," the newspaper adds (Allday, 11/23).

The concept of using antiretrovirals to reduce risk of HIV infection is not new, Scientific American writes: "Doses of antiretrovirals help reduce transmission of the infection from mothers to infants during birth and breastfeeding, and they have been recommended for years as a treatment for people working with HIV-infected fluids who think they might have been exposed to the virus." Though researchers have expressed concerns PrEP could lead to the development of drug-resistant HIV strains, Scientific American reports, "[n]o cases of tenofovir-resistant HIV were detected during the study (and only three cases of emtricitabine resistance were found)" (Harmon, 11/23).

"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 Associated Press reports. "The results are 'a major advance' that can help curb the epidemic in gay men, said Kevin Fenton, AIDS prevention chief at the U.S. Centers for Disease Control and Prevention," the news service reports (11/23).

"The findings have bred new enthusiasm in a field where, for years, optimism was rare," USA Today writes. Still, "[f]ederal 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," the newspaper reports.

"It's no time for gay and bisexual men to throw away their condoms or abandon other ways to prevent HIV," Fenton said, according to the newspaper (Sternberg, 11/23). 

Questions Going Forward

"There are about a half-dozen other studies of PrEP strategies underway around the world, testing both pills and gels in various risk groups," the Washington Post writes.

Still, "[t]he new findings raise questions that public health authorities are already scrambling to answer. … One is whether it is ethical to use placebos in the other PrEP studies. Another is what to tell doctors and patients who want to start using the strategy now," according to the newspaper (Stein, 11/23). 

"In some developing countries where HIV infections are so widespread that they've become a major burden on the economy and the health care system, a preventive drug would be especially welcome, researchers said. They noted, however, that there could be controversy over whether limited AIDS dollars should go toward prevention or toward treatment of those who are already sick," the San Francisco Chronicle reports (11/23).

"A major question now is who will pay for the drug," the New York Times writes. "Globally, only about 5 million of the 33 million people with AIDS are on antiretrovirals, and, in an era of tight foreign-aid budgets, that number is not expected to rise quickly. … Hundreds of millions of Africans, eastern Europeans and Asians are at risk and could benefit from prophylaxis, but that would cost tens of billions of dollars," the newspaper writes (McNeil, 11/23).

Even though the drug combination used in the study has not been officially approved for HIV/AIDS prevention "doctors can prescribe them for that 'off-label' purpose," according to the newspaper. Truvada costs "between $5,000 and $14,000 a year, depending on whether they are bought at retail price or with a bulk discount. In generic form sold to the poorest countries, however, the combination costs as little as $150 per year," according to the Washington Post (11/23).

According to Scientific American, CDC, NIH and others will review the findings and issue guidelines for possible pre-exposure prophylactic antiretroviral use in the coming months (11/23).

"No single HIV prevention strategy is going to be effective for everyone," NIAID Director Anthony Fauci said, according to the NIAID press release. "[I]it is important to note that the new findings pertain only to the effectiveness of PrEP among men who have sex with men and cannot at this point be extrapolated to other populations" (11/23).

The AP reports: "All participants will get a chance to take Truvada in an 18-month extension of the study. Researchers want to see whether men will take the pill more faithfully if they know it helps, and whether that provides better protection. About 20,000 people are enrolled in other studies testing Truvada or its component drugs around the world" (11/23).

A NIAID Q&A elaborates on details of the study (11/23). An accompanying New England Journal editorial also reflects on the findings of the trial (Nelson, 11/23).