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NIH Response: AIDS Vaccine Study in Thailand
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FOR IMMEDIATE RELEASE
Thursday, January 15, 2004
NIAID Office of Communications and Public Liaison
(301) 402-1663
niaidnews@niaid.nih.gov
STATEMENT
RV144, AN ONGOING HIV VACCINE EFFICACY TRIAL IN THAILAND
On Sept. 29, 2003, the U.S. and Royal Thai governments jointly initiated
RV144, a clinical efficacy trial to evaluate a novel HIV vaccine strategy
commonly referred to as "prime-boost." The main objective of this
large-scale, Phase III trial is to determine if a combination vaccine
prevents HIV infection; secondarily, whether it controls HIV if infection
occurs. More than 500 volunteers have already been enrolled in the trial in
two provinces in Thailand.
In a Policy Forum published in the Jan. 16, 2004 issue of Science, Burton
et al. opine that RV144 should not be conducted based on a prediction that
the combination will not be efficacious; that the underlying immune-based
hypothesis has shifted to CD4+ T cells only; and that review and approval
processes lacked adequate scientific expertise and judgment. No evidentiary
data is provided to support the prediction and assertions.
The U.S. government sponsors, the National Institute of Allergy and
Infectious Diseases (NIAID) and the U.S. Army Medical Research & Materiel
Command (USAMRMC), strongly disagree with the authors' opinions. A formal
rebuttal is being prepared for publication in Science in the near future.
The scientific hypothesis being examined in the study is whether a vaccine
combination that induces both arms of the human immune system,
cell-mediated immunity and antibody-mediated immunity, will provide
protection against HIV. The prime-boost comprises a combination of Aventis
Pasteur's ALVAC-HIV (vCP1521) and VaxGen's gp120 (AIDSVAX B/E). In
combination, these vaccines induce a repertoire of immune responses
quantitatively and qualitatively different from those induced by either
component alone. Prime-boost is expected to induce a constellation of
immune responses including CD8+ T cells, CD4+ T cells and antibodies in 25
to 100 percent of volunteers, depending on the laboratory measurement
employed.
Between 1999 and 2001, Thai and U.S. scientists evaluated the prime-boost
in Phase I and II clinical trials and determined that the strategy was safe
and induced immune responses meeting pre-defined and thoroughly-vetted
milestones; and that these data justified conducting an efficacy
evaluation. No laboratory tests or animal models have been demonstrated to
predict HIV vaccine efficacy in humans. Thus, only human trials can
determine efficacy.
Between 2001 and 2002, the RV144 study plan was reviewed and approved by 11
international scientific/technical, ethical and regulatory review bodies in
Thailand, the United States and at the World Health Organization. RV144 is
being conducted under the regulations of both Thai and U. S. Food and Drug
Administrations.
Media inquiries can be directed to the NIAID OCPL media group at 301-402-1663.
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