A US-based HIV vaccine trial is expanding the number of participants it will enroll as well as the scientific questions it will probe.
Conducted in 12 US cities, the HIV Vaccine Trials Network 505 (HVTN 505) study will assess a dual vaccine candidate for safety and whether it can prevent infection, not just curb the virus in a person already infected. Enrollment is increasing from about 1,300 men who have sex with men, and transgender women who have sex with men, to 2,200.
The trial’s scientific scope changed in response to the RV-144 trial in Thailand in 2009, which proved it was possible to for a vaccine to prevent HIV infection. Though the vaccine’s efficacy was too low, the research offered the first-ever evidence that an HIV/AIDS vaccine candidate conferred even modest protection against infection.
“Because of the Thai trial, what we saw in that vaccine actually preventing infection was, wow, we really need to then look differently at HVTN 505 and expand its ability to look at the question: could this vaccine actually also prevent infection, prevent acquisition of HIV?” said Mitchell Warren, head of the AIDS Vaccine Advocacy Coalition (AVAC). Previously, a main outcome was whether a candidate lowered viral load in vaccinated persons who later became infected.
The HVTN 505 trial will assess whether the vaccine candidate stimulates both an antibody response to prevent HIV infection and a cell-mediated immune response to mitigate infection, said Warren.
“It uses a prime-boost combination of two different vaccines,” Warren said. “One is a DNA vaccine that has snippets of HIV that can’t cause HIV at all, but is meant to kind of prime the immune system. And then it has an Adeno 5 (adenovirus type 5, a common cold virus) vaccine boost.”
For more information about the trial, sponsored and funded by the National Institute of Allergy and Infectious Diseases, visit: www.hvtn.org/media/news.html. Volunteers should visit:www.hopetakesaction.org/volunteering/index.html.
from the NIAID statement:
The decision to expand the trial’s primary objectives and size was motivated by scientific findings that came to light after HVTN 505 began. First, the September 2009 results of a major HIV vaccine trial in Thailand showed for the first time that a vaccine can generate modest protection against HIV infection in humans. Consequently, NIAID decided to take a closer look at the immune responses elicited by its other HIV vaccine candidates in clinical trials, including HVTN 505.
Second, a series of studies in nonhuman primates demonstrated that the monkey version of the HVTN 505 vaccine regimen prevented infection by the monkey equivalent of HIV (called SIV) 50 percent of the time in two-thirds of the monkeys tested. This protection occurred in the presence of robust cellular responses and low levels of SIV-neutralizing antibodies. These results suggested that the experimental HVTN 505 vaccine regimen may have the capacity to prevent HIV acquisition in people.
The HVTN is conducting the study under the leadership of Scott M. Hammer, M.D., the chief of the Division of Infectious Diseases and the Harold C. Neu professor of medicine in the College of Physicians and Surgeons at Columbia University.
To volunteer for this study, please visit the Hope Takes Action website.
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