He says there was no response in the 15 patients who were taking anti-AIDS drugs, perhaps because that therapy had already driven the virus down to virtually undetectable levels.
But among the others, an infusion of VRC01 totally knocked out the virus for 20 days in two participants. Others saw their virus load significantly drop for up to three weeks. However, a couple of patients in this group saw no effect, and scientists determined they were infected with drug-resistant strains of HIV.
The results were published in the journal Science Translational Medicine.
Since the virus re-emerged a few weeks after treatment, Fauci says future trials will look at whether HIV can be suppressed with repeat infusions.
"This is an important first step toward determining the feasibility of using monoclonal antibodies for prevention and treatment of HIV," he said.
Researchers have not ruled out using VRC01 to shield high-risk individuals against HIV infection.
Fauci says it's likely the second phase of clinical trials — further testing the safety and effectiveness of the anti-AIDS monoclonal antibody — will take place next year.