VaxGen's
AidsVax: key US Aids campaigns slam
company's "profound disservice"
The
failure of AidsVax to prevent infection
with HIV - in clinical trial results
published in 2003 - triggered an intense
debate about the controversial product
and its manufacturer, VaxGen Inc of
Brisbane, California. Mail to this
website, maintained by Brian Deer, shows that
existing material on a VaxGen-AidsVax
index is read by significant
numbers. This page seeks to
inform the discussion
America's
leading Aids activist organisations
condemned VaxGen's release of what they
called "misleading and
premature" claims about an apparent
ability of AidsVax to protect black and
Asian participants in the company's phase
III vaccine trial. In a consensus
statement on February 24 from the AIDS
Vaccine Advocacy Coalition (AVAC),
Project Inform, the Treatment Action
Group (TAG), and Gay Men's Health Crisis
(GMHC), they said:
The undersigned Community-Based
HIV/AIDS organizations are deeply
concerned by today's presentation of
data from the phase III clinical
trial of VaxGen's HIV vaccine
candidate, AIDSVAX. While the overall
result demonstrates a clear and
disappointing lack of efficacy,
VaxGen has chosen to spotlight
several subgroup analyses that were
not part of the statistical
evaluation described in the original
trial protocol.
Specifically, the company claims that
the vaccine showed an efficacy rate
of 67% in people categorized
demographically as Black, Asian or
"Other" and an even greater
efficacy rate of 78% when results in
Black participants were analyzed
separately.
These results should be treated with
extreme skepticism until subjected to
a detailed, independent scientific
evaluation.
We fear that VaxGen has deliberately
emphasized these putatively positive
findings (on the CNN Financial News
Network, VaxGen CEO Lance Gordon
described them as a "marvelous
result"), while failing to
emphasize that they are based on very
small numbers of infections in a
limited sample of participants. This
may serve the commercial interests of
the company, but it does a great and
profound disservice to the
HIV-affected communities who must now
struggle to make sense of the press
stories that the VaxGen release has
generated.
The Aids organizations
offered "reasons to emphasize
uncertainty":
The smaller the sample
size, the less certain the results.
Among Black trial participants, there
were 9 infections out of 111 placebo
recipients compared to 4 infections
out of 203 vaccine recipients. A
small difference in these rates would
erase the statistical significance of
this finding. VaxGen strongly implies
this result is meaningful by stating
that there is a less than 2%
possibility that it occurred by
chance; however, that does not prove
that the explanation lies with
receipt of the vaccine.
When considered separately,
differences in the infection rates
between placebo and vaccine
recipients among Asian participants
and those categorized demographically
as "Other" were not
statistically significant. Only the
arbitrary grouping together of these
demographic categories with Black
participants allowed VaxGen to claim
a 67% reduction in infection rate
"among ethnic minorities, other
than Hispanic individuals"
(VaxGen Press Release, 2/24/03).
Women in the trial experienced a
lower infection rate than men, and
women were overrepresented among the
non-White, non-Hispanic populations
in the trial. A breakout of the trial
results for women in the different
demographic groups has not yet been
presented.
While the desperate need for an HIV
vaccine is clear, especially among
the underserved communities that bear
the brunt of the pandemic, hope
cannot take flight on the gossamer
wings of dubious subgroup analyses.
It is critical that the scientific
leads that may be contained in the
VaxGen data are vigorously pursued,
but the uncertainty associated with
the results presented today must be
clearly articulated.
The
organizations called on the company to
put its findings to a panel of outside
experts within 30 days.
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