Elusive HIV strains cause breakthrough infections after antibody treatment ends

The broadly neutralizing antibody VRC01 has been thoroughly vetted as a potential prophylactic that could prevent people from becoming infected with HIV. Now, a new analysis of data from two clinical trials in the Americas and sub-Saharan Africa shows that the antibody initially provides strong protection, but that some strains of the virus can still cause breakthrough infections after treatment has stopped.

The findings point to the importance of combining multiple types of antibodies to suppress HIV completely and to prevent breakthrough infections in vulnerable people. Antibodies such as VRC01 are designed to halt the virus' ability to infect its host initially through common sites of exposure. VRC01 has recently progressed to large-scale clinical trials, but scientists must test whether it can provide meaningful, real-world protection against the ever-evolving myriad strains of HIV.

Seeking answers, Allan deCamp and colleagues parsed data from HVTN 704 and HPTN 085, two clinical trials where participants received infusions of VRC01 for 80 weeks. They focused their attention on the period after the treatment ended, from weeks 80 to 104. The researchers showed that VRC01 initially protected against HIV strains that were considered highly sensitive to the antibody, achieving a prevention efficacy of 66.3%. However, after week 80, some of the participants were still diagnosed with HIV that was considered more resistant to the antibody, and diagnoses were higher compared with the placebo group. deCamp et al. write that their results carry implications for the design and analysis of future trials of HIV-1 broadly neutralizing antibodies, such as the importance of testing for the virus far after infusions have ended.