Research Highlights: Potential DNA/rAd5 HIV-1 Vaccine Shown to Be Ineffective in Recent Trial

Potential DNA/rAd5 HIV-1 Vaccine Shown to Be Ineffective in Recent Trial

A study published in the New England Journal of Medicine investigated the efficacy of a new vaccine to prevent HIV-1 infection. The participants in this study were 2,504 men or transgender women who engage in frequent unprotected sex with men, as this demographic has a high risk of contracting HIV-1 within the United States. Experimenters randomly treated participants with either a placebo or the DNA/rAd5 vaccine. This treatment was double-blind. From the 28th week of treatment until the end of the second year of treatment, experimenters checked participants for HIV-1 infection. If participants were diagnosed with the disease during this time then experimenters monitored their viral-load set point (the amount of HIV-1 RNA in their plasma) to observe the progression of HIV-1 infection. 
The vaccine was a DNA/rAd5 regimen composed of two parts: vaccinated participants received three 4-mg injections of the DNA component, then later received one injection of the rAd5 component as a boost.
During the monitoring period of the 28th week until the second year of treatment (referred to as Week 28+), 27 participants receiving vaccinations and 21 participants receiving placebos were diagnosed with HIV-1. The mean viral-load set point for vaccinated participants was 4.46 log10 copies per milliliter, and the mean viral-load set point for placebo-group participants was 4.47 log10 copies per milliliter. The two groups thus had very similar plasma levels of HIV-1 RNA. The vaccine, therefore, did not help to prevent HIV-1 infection and did not reduce viral-load set points in infected patients.
Given the prevalence of HIV/AIDS infection globally, the search for an effective vaccine is a popular research issue. This experiment is the sixth efficacy trial of an HIV-1 preventative vaccine to date, yet almost all of these trial vaccines have been unsuccessful in inhibiting HIV-1 infection. Though no effective treatment has yet been developed, even unsuccessful attempts, such as the vaccine tested in this study, lend important contributions to study of HIV-1 and to the eventual establishment of a working vaccine.

NEJM 2013; 369:2083-2092


Caroline Russell-Troutman is the 2013-2014 Research Highlights Editor