January 26, 2021
Today at a press conference hosted by the HIV Research for Prevention (HIV R4P) conference, research teams presented a range of data from ongoing studies of antibody-mediated prevention, long-acting injectable PrEP, a monthly PrEP pill, and trends in daily oral PrEP use. Together, they point to a future of biomedical HIV prevention research and programs with a greater understanding of mechanisms of prevention, enhanced trial designs and a wider range of prevention options.
HIV R4P Virtual 2021 begins officially on January 27th. Today’s press conference offered top-line findings from the full scientific presentations that will be made later this week. These data have not yet been published in peer-reviewed journals but warrant close attention for their implications for the field.
At the press conference, researchers from the NIH-funded HIV Vaccine Trials Network (HVTN) and HIV Prevention Trials Network (HPTN) presented initial data from the Antibody-Mediated Prevention (AMP) trials of an HIV-specific broadly neutralizing antibody (bNAb) called VRC01, delivered intravenously once every eight weeks. The trials enrolled cisgender women in sub-Saharan Africa and gay men and transgender persons who have sex with men in Brazil, Peru, Switzerland and the United States. According to Larry Corey, AMP Studies protocol chair and principal investigator of the HVTN, VRC01 did not significantly reduce the overall risk of HIV acquisition in participants who received the antibody compared to those who received the placebo. However, VRC01 did safely and effectively reduce the risk of acquiring HIV strains classified as “highly-sensitive” to neutralization by VRC01.
“These were complex and well-designed trials of a novel HIV prevention concept, and the results move the field forward in important ways,” said Mitchell Warren, AVAC Executive Director. “The AMP trials show that a broadly neutralizing antibody can reduce the risk of acquiring viruses that are very sensitive to that antibody. This is welcome news; it is the first evidence in humans that intravenous infusions of a broadly neutralizing HIV antibody can reduce a person’s risk of acquiring HIV via sex.”
The AMP results also demonstrate the extent of the challenge that lies ahead for antibody-mediated prevention. There are multiple strains of HIV circulating through communities. The trial team used lab tests to predict how many HIV strains in trial communities would be sensitive to, and blocked by, VRC01. The trial data didn’t match these predictions. Fewer viruses were highly-sensitive to VRC01 than the AMP team had hoped. The trials showed that a bNAb like VRC01 does not offer sufficient protection on its own and that a combination of bNAbs is likely needed if broad protection is to be achieved.
“AVAC is grateful to the research teams, trial participants, clinic staff and community advocates who made these trials possible. The next step for the prevention field is to determine how these results can be used to guide the selection of combination bNAb products to advance to efficacy trials. Advocates should monitor — and be engaged in — these deliberations,” said Stacey Hannah, AVAC’s Director of Research Engagement.
“With new prevention options like the Dapivirine Vaginal Ring and injectable cabotegravir for PrEP advancing towards licensure, people at risk of HIV will have more choices. This is a great thing. As choice expands, efficacy trials of future products will need to be designed in new ways, and advocates’ support for investigation of bNAbs as part of this prevention pipeline is crucial,” said Hannah, who also led the development of AVAC’s Advocates’ Trial Design Academy that is engaging with developers and trial designers in considering the future.
Participants in the AMP trials received one of two different doses of VRC01 or a placebo administered every eight weeks via intravenous infusion. Some participants — in both the placebo and VRC01 arms — acquired HIV in spite of counseling, condom provision and PrEP referrals and counseling at all study sites. Viruses from these participants were isolated from their blood samples, sequenced and analyzed in the laboratory to determine the concentration of VRC01 that blocked viral activity. Viruses neutralized with a