Neutralizing Antibodies to Prevent HIV Acquisition: A Foot in the Door

Broadly neutralizing antibodies (bNAbs) such as VRC01 are a focus of study for HIV treatment and prevention (NEJM JW Infect Dis Jan 2017 and N Engl J Med 2016 Nov 16; 375:2037). Now, two phase 3 placebo-controlled trials to evaluate whether VRC01 can prevent HIV acquisition are yielding tantalizing findings. One study (in Europe, the U.S., and South America) enrolled 2699 cisgender men and transgender persons who have sex with men or transgender persons. The other trial enrolled 1924 at-risk women in sub-Saharan Africa. Participants were randomized 1:1:1 to receive intravenous infusions of VRC01 (10 or 30 mg/kg) or placebo every 8 weeks. An in vitro assay was used to determine the 80% VRC01 inhibitory concentration (IC₈₀) of acquired isolat…