Clinical Trials Testing Viread in MSM for HIV Prevention To Begin in Atlanta, San Francisco
Clinical trials of the antiretroviral drug Viread among HIV-negative men who have sex with men will begin this month in San Francisco and Atlanta to determine whether the drug can reduce the risk of HIV infection, the San Francisco Chronicle reports (Russell, San Francisco Chronicle, 12/1). NIH, CDC and the Bill & Melinda Gates Foundation are funding three separate human studies of Viread, which is known generically as tenofovir and manufactured by Gilead Sciences. The drug is FDA-approved for use as a treatment for HIV infection and has been shown to boost immune response and lower viral levels in the bloodstreams of patients who are resistant to other antiretrovirals. CDC has granted $3.5 million to fund the trials in San Francisco and Atlanta, while the Gates Foundation awarded a $6.5 million grant to Family Health International to conduct a randomized, placebo-controlled clinical trial including 2,000 HIV-negative volunteers in Cambodia, Ghana, Cameroon, Nigeria and Malawi. NIH also awarded a $2.1 million grant to University of California-San Francisco researchers to test Viread in 960 HIV-negative Cambodian women, most of whom are commercial sex workers (Kaiser Daily HIV/AIDS Report, 2/6). However, Cambodian Prime Minister Hun Sen in August ordered a stop to the planned human clinical trial in the country because of the possible effects of the drug on trial participants (Kaiser Daily HIV/AIDS Report, 8/12).
The trials in San Francisco and Atlanta are designed to determine if Viread is safe to use for HIV prevention among MSM and if using the drug would result in an increase in unsafe-sex practices and higher HIV incidence, according to the Chronicle. If any of the participants contract HIV while taking Viread, researchers can determine whether the strain they contract is resistant to the drug. In each city, 200 MSM will be enrolled in the double-blind study and be assigned to take Viread or a placebo every day for two years. However, because the study is relatively small, there will not be enough data after two years to determine if taking Viread daily can significantly reduce the risk of HIV infection, the Chronicle reports. Therefore, CDC is launching two larger trials of the drug among HIV-negative volunteers in Botswana and Thailand. In Botswana, where nearly 40% of adults are HIV-positive, the trial will enroll 1,200 HIV-negative men and women ages 18 to 29 living in Gabarone and Francistown -- the country's two largest cities. In Bangkok, Thailand, 1,600 HIV-negative injection drug users will be enrolled in the study.
Researchers involved with the Viread studies "must weave through an ethical minefield to be certain that participants are fully educated about the risks involved," as is the case with most HIV/AIDS vaccine trials, according to the Chronicle. The participants will be "repeatedly counseled" on safe-sex practices -- including condom use -- and also will be "warned that there is no way they can know if they are given an active medication" or a placebo, the Chronicle reports. Participants also will be informed that even if they receive Viread, it might not be effective at preventing infection. However, researchers "fear" that if the evidence indicates that Viread might provide some protection against HIV infection, then people taking the drug may not be as motivated to practice safer sex, according to the Chronicle. Ideally, 100% of study participants would remain HIV-negative, indicating that HIV "can be stopped by education alone," according to Dr. Susan Buchbinder, director of HIV research at the San Francisco Department of Public Health, the Chronicle reports. However, previous studies have shown that even when provided with counseling, 2% to 4% of individuals who engage in high-risk behaviors contract HIV (San Francisco Chronicle, 12/1).