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HIV vaccine fails in first large trial; may protect Blacks, Asians only
The long awaited results of
the first phase III HIV vaccine study released today show that Vaxgen’s AIDSVax
offered no significant protection against HIV infection in the study population
as a whole. However the study did show a statistically significant reduction in
HIV infections among black and Asian volunteers, which correlated with a higher
level of vaccine-induced neutralising antibodies.
AIDSVax was tested in 5,417
volunteers in North America and the Netherlands in a 36 month randomised
placebo controlled study. 5,009 volunteers received at least three of the seven
scheduled injections.
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The
results appear to suggest that AIDSVax may be more effective in individuals of
African origin. All participants were infected with HIV-1 subtype B, so this
result does not imply that AIDSVax is more effective against subtypes of HIV
found in Africa, Asia and Latin America.
However,
Seth Berkley, President of the International AIDS Vaccine Initiative,
highlighted the limitations of this finding.
"The
results on AIDSVAX must be further analyzed, and independently reviewed. For
example, VaxGen's preliminary analysis of the small number of nonwhite
volunteers suggests that there were fewer infections among black volunteers who
received AIDSVAX than blacks who received the placebo. However, it is difficult
to draw conclusions about what this means, given that the number of blacks in the
study was so small (VaxGen's analysis is based on just 13 infections among
black volunteers, 4 in the vaccine group and 9 in the placebo group).”
Vaxgen says
that although the subgroup sample sizes were relatively small compared to the
entire study sample, the results are statistically significant.
“With
regard to ethnic minorities in the trial, there is less than a 1% possibility
that the observed difference in infection rates could have occurred by chance”,
the company said in its press release. “There is less than a 2% possibility
that the observed difference in infection rates among black volunteers could
have occurred by chance. In addition to the results in those receiving three
doses, the reduction in infection in individuals who received at least one dose
of vaccine or placebo were similar and also statistically significant.”
the first phase III HIV vaccine study released today show that Vaxgen’s AIDSVax
offered no significant protection against HIV infection in the study population
as a whole. However the study did show a statistically significant reduction in
HIV infections among black and Asian volunteers, which correlated with a higher
level of vaccine-induced neutralising antibodies.
AIDSVax was tested in 5,417
volunteers in North America and the Netherlands in a 36 month randomised
placebo controlled study. 5,009 volunteers received at least three of the seven
scheduled injections.
| Study
Demographics |
|
| Number of volunteers to complete three immunizations: | 5,009 |
| Placebo recipients: | 1,679 |
| White volunteers: | 4,185 |
| Hispanic volunteers: | 326 |
| Non-white volunteers (Black, Asian, Other): | 498 |
| Black volunteers: | 314 |
| Annual study infection rate | 2.7% |
| Approximate Efficacy (after at least 3 primary doses) | |
| All volunteers: | 3.8% (p-value = 0.76; confidence interval: -23% to 24%) |
| Non-white volunteers: | 67% (p-value < 0.01; confidence interval: 30% to 84%) |
| Black volunteers: | 78% (p-value < 0.02; confidence interval: 29% to 93%) |
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The
results appear to suggest that AIDSVax may be more effective in individuals of
African origin. All participants were infected with HIV-1 subtype B, so this
result does not imply that AIDSVax is more effective against subtypes of HIV
found in Africa, Asia and Latin America.
However,
Seth Berkley, President of the International AIDS Vaccine Initiative,
highlighted the limitations of this finding.
"The
results on AIDSVAX must be further analyzed, and independently reviewed. For
example, VaxGen's preliminary analysis of the small number of nonwhite
volunteers suggests that there were fewer infections among black volunteers who
received AIDSVAX than blacks who received the placebo. However, it is difficult
to draw conclusions about what this means, given that the number of blacks in the
study was so small (VaxGen's analysis is based on just 13 infections among
black volunteers, 4 in the vaccine group and 9 in the placebo group).”
Vaxgen says
that although the subgroup sample sizes were relatively small compared to the
entire study sample, the results are statistically significant.
“With
regard to ethnic minorities in the trial, there is less than a 1% possibility
that the observed difference in infection rates could have occurred by chance”,
the company said in its press release. “There is less than a 2% possibility
that the observed difference in infection rates among black volunteers could
have occurred by chance. In addition to the results in those receiving three
doses, the reduction in infection in individuals who received at least one dose
of vaccine or placebo were similar and also statistically significant.”