UCSF begins study testing antiviral drug tenofovir to prevent HIV infection

By Jeff Sheehy

UCSF researchers have been funded by the National Institutes of Health to study the antiretroviral drug tenofovir as a potential pre-exposure prophylaxis in Cambodia among high-risk, HIV-uninfected women.  The research will look at safety and effectiveness of the drug in preventing the acquisition of HIV.

“With both a vaccine and a microbicide many years down the road, we are hoping that this once-a-day pill—a potent, low toxicity medication used in anti-HIV combination therapy—can be taken by uninfected people at high risk for HIV infection and will keep them from becoming infected,” said study principal investigator, Kimberly Page Shafer, PhD, MPH, assistant professor of medicine at the UCSF Center for AIDS Prevention Studies (CAPS).

Although studies of tenofovir to prevent HIV transmission in animals have been promising, the effectiveness of this drug for preventing HIV-1 transmission in people is not known and will be evaluated in the planned research. The study will recruit 800 adult HIV-uninfected women who are at high risk for HIV infection.  The study will be a randomized, double blind clinical trial with participants chosen at random to receive either tenofovir or a placebo.

Participants will take one pill a day for 12 months.  At the beginning and once a month during the trial, study subjects will receive counseling to reduce risky behavior, free condoms, and free screening and treatment of sexually transmitted infections.

Participants will be tested monthly for HIV and those who become infected during the study will be referred to an HIV treatment clinic for comprehensive care, including anti-HIV therapy if medically indicated.  Effectiveness will be determined by comparing HIV infection rates between the group taking tenofovir and the one taking the placebo.

Study participants will be monitored for drug safety and adverse effects.  Drug safety will be examined by comparing the occurrence of side effects in the group taking tenofovir with the one taking placebo.

The study will be conducted under the auspices of the Kingdom of Cambodia’s Ministry of Health’s National Center for HIV/AIDS, Dermatology and STDs in collaboration with researchers from UCSF and the University of New South Wales, Australia (UNSW). The study’s grant award is for three years.

Other investigators for the study from UCSF are Robert M. Grant, MD, MPH, assistant investigator at the Gladstone Institute for Virology and Immunology, and UCSF assistant professor of medicine and Krysia Lindan, MD, UCSF associate professor of epidemiology.  Margery Lazarus, PhD, MPH, medical anthropologist at UCSF CAPS, will lead formative social research for the study.

Funding for the study comes from two sources.  NIH is funding UCSF, and the Bill and Melinda Gates Foundation is funding UNSW.  Gilead Inc., the manufacturer, is providing placebo and tenofovir at cost (per an arrangement for developing countries, including Cambodia), and no other support or assistance.