Feb 13, 2004  |  By: CHRISTOPHER SEELY  | COMMENTS     

ATLANTA — Some 400 men in Atlanta and San Francisco are scheduled to take part in a $3.5 million study beginning later this year to measure the safety of a drug that might be used to prevent HIV infection until an AIDS vaccine is found.

The Centers for Disease Control & Prevention is funding the study of the drug tenofovir at the AIDS Research Consortium of Atlanta and with researchers in San Francisco as an alternative to a vaccine.

“We need to explore every possibility for preventing new infections, including biomedical solutions,” said Dr. Lynn Paxton, CDC section chief for sexual transmission and intravenous drug use studies.

In 2001, the Food & Drug Administration approved the drug, also known as Viread, to fight HIV. People who are HIV-positive can now use Viread in combination with other HIV medications, but the new CDC study would examine the safety of Viread as a prevention pill, specifically in high-risk, HIV-negative men who have sex with men.

Tenofovir is taken once a day, is proven safe in people with HIV and has garnered promising data in tests on monkeys, all factors in why the CDC wants further research on the drug, said Dr. Melanie Thompson, principal investigator at ARCA.

A small number of monkeys given tenofovir prior to SIV exposure did not contract SIV, the monkey form of HIV, according to Thompson.

A preventative measure like Viread would be useful in combating HIV because an AIDS vaccine isn’t yet a reality, said Jim Rooney, vice president of clinical research at Gilead, the biopharmaceutical company that manufactures the drug.

“We desperately need a vaccine, but unfortunately it doesn’t look like one is going to be available in the near term,” Rooney said. “It could be an effective alternative strategy for preventing HIV infection.”

Gilead, based in Foster City, Calif., donated the Viread needed for the CDC study, which will measure the side effects of the pill in participants over a two-year period. Half of the study participants will receive a placebo and half will receive the drug.

In HIV-positive people who take Viread, side effects include upset stomach, nausea and diarrhea, based on past studies conducted by Gilead, Rooney said.

More serious hazards include kidney toxicity and bone fractures, which result from a loss of bone density, Rooney said.

But participants in the new study, which will probably begin this summer in Atlanta, would be forewarned of the side effects and monitored for kidney and bone density abnormalities, Thompson said.

The study will also provide information on whether participants alter their sexual behavior while taking the drug, according to Paxton.

“If other research finds that this approach is effective, then data from this study on long-term safety for uninfected men and its impact on risk behavior will be invaluable,” Paxton said.

But researchers want to be clear that the pill is not a proven preventative measure against HIV, Thompson said.

“There are multiple risks associated with taking the drug — not the least of which is that if people think they can use tenofovir instead of condoms, they may be at even higher risk for HIV infection,” Thompson said.

Researchers seek HIV-negative men who have sex with other men, ages 18 to 60, for the study, which pays $25 per visit. It is critical, Thompson said, for black and Latino men to apply. Free rapid HIV testing will be offered for participants throughout the study.

The CDC study in Atlanta and San Francisco is part of a larger study of the drug, including a $2.1 million study by the National Institutes of Health and a $6.5 million study by the Bill & Melinda Gates Foundation, according to CDC.

The Gates Foundation study will use 1,200 women and 400 heterosexual men in Africa. The NIH trial, conducted by the University of California in San Francisco, is testing 900 Cambodian women.