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Medical
News
July 17, 2008
STATEMENT
NIAID Will Not Move Forward with the
PAVE 100 HIV Vaccine Trial
After soliciting and considering broad input from the scientific and HIV
advocacy communities, the National Institute of Allergy and Infectious
Diseases (NIAID), part of the National Institutes of Health (NIH), has
determined that it will not conduct the HIV vaccine study known as PAVE
100. However, NIAID believes the vaccine developed by its Vaccine
Research Center (VRC) is scientifically intriguing and sufficiently
different from previously tested HIV vaccines to consider testing it in
a smaller, more focused clinical study. Therefore, NIAID will entertain
a proposal for an alternative study with one specific goal: to determine
if the vaccine regimen significantly lowers viral load—the amount of HIV
in the blood of vaccinated individuals who may later become infected
with HIV.
The original PAVE 100 study, as presented to NIAID's AIDS Research
Advisory Committee in January 2007, proposed to test the VRC's HIV
vaccine regimen in a trial initially designed to enroll 8,500 volunteers
in the United States, South America, the Caribbean and Eastern and
Southern Africa. The study was to begin U.S. recruitment in October 2007
but was postponed last fall following the decision to halt immunizations
in the STEP HIV vaccine study (see Immunizations Are Discontinued in Two
HIV Vaccine Trials <http://www3.niaid.nih.gov/news/newsreleases/2007/step_statement.htm>
). That decision was made after it was determined that the vaccine used
in the STEP trial, an investigational product developed by Merck & Co.
Inc., failed to prevent HIV infection or reduce viral load.
Subsequent analyses of the STEP trial found increased numbers of HIV
infections among those volunteers who received the vaccine in comparison
to those who received the placebo; the Merck vaccine itself did not
cause HIV infection. The highest risk of HIV infection among vaccinees
compared with placebo recipients appeared to be among males who were
both uncircumcised and had pre-existing neutralizing antibodies to
adenovirus type 5 (Ad5), the common cold virus used in the vaccine as a
carrier for the HIV genes. Vaccination resulted in no apparent increased
risk in men who were circumcised and who lacked pre-existing
neutralizing antibodies to Ad5. The VRC vaccine regimen that was to be
tested in the PAVE 100 study has two components, one of which includes
an Ad5-based carrier, which is administered to boost immune responses
that are first stimulated with a DNA vaccine.
Based on the analyses of the STEP study results, PAVE 100 was redesigned
and reduced somewhat in its proposed scope, although it remained a
scientifically and logistically complex study. The redesigned PAVE 100
study would have involved testing the VRC vaccine in 2,400 U.S.-based,
circumcised men who have sex with men and who lack preexisting
neutralizing antibodies to Ad5. The redesigned study would have tested
the vaccine's effect on viral load, provided additional safety
information about the product, and examined in detail immune responses
to the vaccine and their impact on viral load.
Based on the available scientific information, NIAID has decided that
the VRC vaccine regimen did not warrant a trial of this size and scope
and that PAVE 100 will not proceed. However, NIAID will entertain a
smaller, more focused clinical trial designed to answer one important
question: Does the product have a significant effect on HIV viral load?
If such an effect is noted, then additional studies or expansion of the
study to carefully examine immunological correlates could be performed.
NIAID will consider such an alternative study and will announce its
decision at a later time.
An HIV vaccine continues to be our best hope for ending the HIV
pandemic. NIAID is committed to supporting the basic research and
vaccine discovery needed to design promising vaccine candidates and
testing those candidates when appropriate. Visit NIH's clinical trials
site for information about clinical HIV vaccine research supported by
NIAID <http://clinicaltrials.gov/ct2/results?term=HIV+vaccine+and+NIAID&recr=Open>
.
Media inquiries can be directed to the NIAID Office of Communications at
301-402-1663,
niaidnews@niaid.nih.gov <mailto:niaidnews@niaid.nih.gov>
.
Reauthorize Our Pledge to Fight AIDS
Thursday 29 May 2008
by: Wendy Johnson and Jennifer Kasper, The Seattle
Post-Intelligencer
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