The broadly neutralizing antibody VRC01 showed early protection against HIV-1 strains that are highly sensitive to it, but some more resistant infections were detected after treatment ended, according to an analysis of two clinical trials. The results suggest that a single antibody may not be enough to prevent viral escape and breakthrough infections.
Researchers analyzed data from HVTN 704 and HPTN 085, in which participants received intravenous VRC01 infusions over 80 weeks. They examined HIV acquisition through the final study visit at week 104, focusing on the period after the last dose, which was given at week 72.
For viruses considered highly sensitive to VRC01, the antibody’s cumulative prevention efficacy was 66.3%. The analysis indicates that as VRC01 concentrations declined, some infections involving viruses with greater resistance became detectable. After week 80, HIV diagnoses and resistance to VRC01 were more frequent in the VRC01 groups than in the placebo group.
VRC01 targets the CD4-binding site on HIV’s envelope glycoprotein, helping neutralize susceptible strains. The study’s authors say the findings support investigating combinations of antibodies to address both sensitive strains and viral escape. They also highlight the importance of monitoring participants well after antibody infusions have ended in future trials.