发信人: Eddy (打哪儿指哪儿), 信区: Biology
标 题: First AIDS Vaccine Disappoints but Leaves Hope
发信站: The unknown SPACE (Mon Feb 24 19:07:37 2003) WWW-POST

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) - The first attempt to develop a vaccine to prevent AIDS
has failed, vaccine-maker VaxGen Inc. said on Monday, but there was a ray of
hope it could help blacks and Asians.



Long-awaited results from VaxGen's trial of AIDSVAX show the vaccine reduced
the rate of HIV infection by just 3.8 percent in 5,000 men and women
considered at high risk in the United States, Canada, Puerto Rico and
Netherlands.


"Overall, what we see is the trial failed," VaxGen President Dr. Donald
Francis told a conference call.


The vaccine was tested only against the strains of the virus found in North
America and Europe, so the findings do not apply to Africa and Asia, the
regions hardest-hit by AIDS.


Most AIDS researchers had not expected AIDSVAX to protect very many people
from infection with the human immunodeficiency virus. But they were intrigued
by the findings that the vaccine seemed to offer protection to blacks and
Asians but not to whites and Hispanics.


For the study VaxGen gave injections of either the vaccine or placebo to 5,108
gay and bisexual men and 309 high-risk women. They started in 1998 and then
watched to see who went on to become infected with HIV.


All the volunteers were told about safe sex practices such as using condoms to
protect themselves and partners.


When VaxGen's figures were analyzed, they showed that Asians, blacks and
self-described "others" who got the vaccine had a 67 percent lower rate of
infection than those who got a placebo shot.


Shares in the company, based in Brisbane, California, closed down $6.16 or
47.31 percent at $6.86 on Monday.


LITTLE INFORMATION TO WORK WITH


There were only 498 blacks and Asians and "others" in the trial, so the
numbers are difficult to interpret. Of all 5,000 volunteers only 127 became
infected with HIV -- only 25 among the blacks and Asians -- which is a small
number of cases to draw any conclusions from.


"The company is claiming that this vaccine works better in African Americans
and other non-Hispanic racial subgroups based on a difference of five people,"
Martin Delaney of AIDS information group Project Inform said in a statement.


"This is at best premature and irresponsible data reporting."


"VaxGen has not proven that this vaccine is effective among African Americans
or Asians, yet preliminary press reports are claiming that this may be the
case," agreed Ana Oliveira, Executive Director of Gay Men's Health Crisis.


But the company said blacks and Asians seemed to produce more antibodies
against the virus than others. It will be worth was examining these patients
see if they could provide clues to improve the vaccine, said Dr. Neil Flynn of
the University of California Davis, who worked on the trial and helped
interpret the results.


"I think personally that there is enough here to warrant a lot more study,
particularly in people of African American descent," Flynn said in a telephone
interview.


One thing the company and the U.S. Food and Drug Administration were looking
for was evidence the vaccine could act therapeutically -- to help reduce the
devastating effects the virus has on the immune system.





AIDS kills patients by destroying their immune systems, leaving them
vulnerable to other infections.

Flynn said there was some suggestion the vaccine might reduce how much virus
is in the blood. "The tendency that many of us noticed at the clinical end was
that their viral load setpoint was lower than what we are used to," he said.

ANSWER MAY LIE IN THE GENES

"If the antibody response does turn out to be higher in people of African
heritage, the question is why. We can find out what it is and find out a way
to effect it in people who don't have it," Flynn said.

"This needs to be resolved soon because if this vaccine works in people of
African American descent then it needs to be considered to make it available
if possible."

Phill Wilson, Executive Director of the Black AIDS Institute, a Los
Angeles-based think tank, agreed.

"AIDS is the number one killer of young black men in the U.S. because the
interventions we already have don't reach enough African Americans. With or
without an effective vaccine, that has to change," Wilson said in a statement.


Francis said it was not immediately clear if the numbers would be enough to
satisfy the FDA, which had been looking for at least a 30 percent rate of
protection from infection.

"Clearly we will move toward licensure -- the question is whether we will do
it with this study," he said. He said VaxGen would meet with the FDA to
discuss what to do.

Campaigners said the results showed that work must continue to develop an AIDS
vaccine. Nineteen different vaccines are in human trials around the world.

"The news on VaxGen's AIDSVAX is disappointing, but we are not discouraged.
The search for an AIDS vaccine will and must go on," said Dr. Seth Berkley,
president of the International AIDS Vaccine Initiative in New York.

Merck & Co. Inc., GlaxoSmithKline Plc, Aventis Pasteur SA, as well as
government and nonprofit researchers in the United States, Britain, France,
Uganda are all testing AIDS vaccines.

Other researchers have said that stimulating an antibody response using this
approach would not be enough to vanquish HIV, which can mutate and evade the
body's immune responses.




--
※ 来源:．The unknown SPACE bbs.mit.edu．[FROM: 172.169.]