October 8, 2013
An investigational HIV vaccine was not successful at reducing the rate of HIV acquisition among a high-risk population group, according to data published in The New England Journal of Medicine.
“Our study gave a definitive, albeit disappointing, result but should provide useful information as newer vaccine regimens and approaches are developed,” the researchers wrote.
The HIV Vaccine Trials Network (HVTN) 505 study team evaluated the efficacy of a DNA prime–recombinant adenovirus type 5 boost (DNA/rAd5) vaccine among people at risk for HIV in the United States. The 6-plasmid DNA vaccine was given at weeks 0, 4 and 8, and the rAd5 vector boost was given at week 24. The study included 2,504 men or transgender women who have sex with men. They were randomly assigned to receive the vaccine (n=1,253) or placebo (n=1,251). The researchers evaluated HIV acquisition from week 28 through month 24.
The data and safety monitoring board halted the trial in April 2013 because of a lack of efficacy. In the primary analysis, 27 participants in the vaccine group and 21 participants in the placebo group developed HIV infections after week 28, for a vaccine efficacy of –25% (95% CI, –121.2 to 29.3). The researchers also evaluated the mean viral-load set points, which were 4.46 HIV RNA log10 copies/mL for those in the vaccine group and 4.47 HIV RNA log10 copies/mL for the placebo group.
From enrollment through week 28, there were 24 infections (14 in the vaccine group and 10 in the placebo group) for a total of 72 HIV infections from enrollment through month 24.
“Thirty years after the discovery of HIV, a safe and effective vaccine is still not in sight,” the researchers wrote.