International trials test HIV prevention antibody

The antibody VRC01, discovered in the blood of an HIV-positive person in 2010, prevents 90 percent of the world's HIV strains from infecting cells and may help lead to a vaccine against the virus. Photo by ktsdesign/Shutterstock

BETHESDA, Md., April 7 (UPI) -- The National Institutes of Health is launching two trials of an antibody thought to prevent HIV infection, which researchers say could help the development of a vaccine against the virus.

The AMP, or antibody-mediated prevention, studies will test the efficacy of VRC01 to prevent infection in HIV-negative high-risk people in the United States, South America and Africa during the next six years, the agency said in a press release.

The daily pill pre-exposure prophylaxis, or PrEP, sold as Truvada, has been shown in several studies to effectively reduce the risk of acquiring HIV, as well as shown to be as safe to take as aspirin.

Unlike PrEP, VRC01 is an injection, given every eight weeks, an aspect researchers said may help keep people on the drug regimen better than remembering to take a pill every day.

VRC01 is an antibody found in the blood of an HIV patient in 2010 that, when cloned and manufactured was found to stop 90 percent of known HIV strains from infecting cells. Considered a broadly neutralizing antibody, researchers say it has the potential to help development of an HIV vaccine.

"Injections or infusions of antibodies to prevent acquisition of an infectious disease have been utilized in medicine for decades," said Dr. Larry Corey, a researcher involved with the trials and professor of medicine at the University of Washington. "The remarkable advance in technologies to isolate and manufacture human monoclonal antibodies in concentrations high enough to potentially prevent HIV is a major development that makes these exciting trials possible."

Phase 1 is already underway in Brazil, Peru and the United States with 2,700 men and transgender people who have sex with men. The second phase will launch later this year with 1,500 sexually active women in Botswana, Kenya, Malawi, Mozambique, South Africa, Tanzania and Zimbabwe.

The participants in both trials, HIV-negative but at high risk for aquiring it, will be randomized to receive either a 30 milligram-per-kilogram dose of VRC01, a 10 milligram-per-kilogram dose or saline for 80 weeks, and will be followed for 20 weeks after that.

Participants will be tested for HIV every four weeks, or when they may have been exposed to the virus, given condoms and lubricant, and continue taking PrEP if they currently do or will be referred to a local program that provides it. Researchers say the study is designed to allow them to measure the preventive nature of VRC01 even if some participants are taking PrEP.

"The AMP Studies could have a major impact on the future of HIV prevention and may be especially informative to HIV vaccine research," said NIAID Director Anthony S. Fauci, M.D. "Many scientists believe that if a vaccine were developed that elicited broadly neutralizing antibodies in healthy people, it would protect them from HIV infection. The AMP Studies will test this hypothesis by directly giving people the VRC01 antibody."