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Thursday 27th July, 2006
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H5N1 pandemic flu vaccine achieved a
high immune response at a low dose of antigen in
clinical trials.
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GlaxoSmithKline (GSK) plc today announced headline data
showing that its H5N1 pandemic flu vaccine achieved a high
immune response at a low dose of antigen. The vaccine, which
uses a proprietary adjuvant, enabled over 80% of subjects who
received 3.8?g of antigen to demonstrate a strong seroprotective
immune response.
This level of seroprotection meets or exceeds target criteria
set by regulatory agencies for registration of influenza
vaccines. Efficacy results at these levels of antigen dosage
have also not been reported for any other H5N1 vaccine in
development to date, including those using other adjuvants such
as alum.
Commenting on the data, JP Garnier, GlaxoSmithKline?s Chief
Executive Officer, said: ?These excellent clinical trial results
represent a significant breakthrough in the development of our
pandemic flu vaccine. This is the first time such a low dose of
H5N1 antigen has been able to stimulate this level of strong
immune response.
There is still a lot more work to be done with this programme,
but this validation of our approach provides us with the
confidence to continue developing the vaccine, including
assessment of its ability to offer cross-protection to variants
of the H5N1 strain. All being well, we expect to make regulatory
filings for the vaccine in the coming months.?
The results were based on an interim analysis of a clinical
trial conducted in Belgium which involved 400 healthy adults
aged 18-60 years of age. The vaccine tested was produced from
inactivated H5N1 virus and contained a novel, proprietary
adjuvant. An adjuvant is an ingredient which stimulates the
immune system and increases response to the vaccine. Trial
participants were vaccinated twice during the course of the
trial and four different levels of antigen dose were tested,
with 3.8?g being the lowest dose assessed.
In this study, immune response was defined as the increase in
the number of antibodies an individual produced in response to
the vaccine. Levels of antibody protection were established
through measurement of hemagglutination inhibition (HI),
hemagglutination being the clumping together of red blood cells,
which cannot occur when antibodies are present. HI is a standard
efficacy measure used in the evaluation of influenza vaccines,
and an individual with an HI titer of greater than 40 is
considered to be protected, or to have ?seroprotection.? In this
clinical trial, over 80% of subjects, who received 3.8?g of
antigen with adjuvant, demonstrated a seroprotective immune
response. GSK?s adjuvanted investigational pandemic vaccine has
not received marketing approval from any regulatory agency.
GlaxoSmithKline is one of the world?s leading research-based
pharmaceutical and health care companies. GlaxoSmithKline is
committed to improving the quality of human life by enabling
people to do more, feel better and live longer.
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