AIDS vaccine fails during human trials
I don't think even Jack Friday could laugh at this one. Merck halted human trials of their AIDS vaccine last week after it failed. (The STEP trial):
Researchers did not expect the vaccine to prevent infection, but had hoped that it might hinder the growth of the virus enough to delay the onset of full-blown AIDS and make it harder for an infected individual to transmit HIV to others, creating a stopgap while they searched for a more effective therapy.
…
…but an independent monitoring panel conducted a scheduled review of the vaccine's effectiveness and found that 24 of 741 participants injected with the vaccine had contracted HIV, compared with 21 of 762 given a dummy vaccine, Merck said in a statement last week. The two infected groups had nearly the same levels of virus in the blood.
The next step is to figure out why it failed. Full results will probably be published sometime in 2008. Right now, researchers figure the it's because a T-cell vaccine isn't enough to stave off AIDS.
Conventional vaccines work by triggering the immune system into manufacturing antibodies against an infectious organism, but such a vaccine has proved elusive for the rapidly mutating HIV.
Researchers for the past decade have focused on the T cell approach, based on studies showing that monkeys receiving such vaccines against simian immunodeficiency virus, related to HIV, lived longer or had lower viral levels than usual.
In V520, each of three HIV genes—gag, pol and nef—was inserted into a weakened adenovirus, one of the viruses that cause the common cold. Human cells infected by the viruses produced the gene products, giving T cells an advance exposure to them.
This is truly unfortunate news.
[tags]HIV, AIDS, STEP trial, Merck[/tags]
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