"First AIDS Vaccine May Protect Minorities-Vaxgen"
Monday February 24, 3:48 am ET
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - The first AIDS vaccine to be tested in people does not offer much protection to the general population but may protect blacks and Asians, vaccine-maker VaxGen Inc. said Monday.
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Long-awaited results from VaxGen's trial of AIDSVAX show the vaccine only reduced the rate of HIV infection by 3.8 percent in 5,400 men and women considered at high risk, VaxGen said in a statement.
Dr. Seth Berkley, president and CEO of the International AIDS Vaccine Initiative, called the announcement "disappointing."
When VaxGen's figures were analyzed closely, they showed that Asians and blacks who got the vaccine had a 67 percent lower rate of infection that those who got a placebo shot.
"There were 78 percent fewer HIV infections among black volunteers who received vaccine compared to placebo recipients," the Brisbane, California-based company added in a statement.
The company said it hoped this might be a first step toward fighting a virus that has killed 28 million people worldwide and infects 40 million now.
"This is the first time we have specific numbers to suggest that a vaccine has prevented HIV infection in humans," Phillip Berman, VaxGen's senior vice president of research and development, said in the statement.
There were only 314 blacks and a total of 498 blacks and Asians in the trial, so the numbers are difficult to interpret. But they offer enough hope for the company to continue development of the vaccine, said Lance Gordon, chief executive of VaxGen.
"We intend to continue development of this vaccine through licensure, including additional studies as necessary, for use in groups in which the vaccine demonstrated a significant reduction in infection," Gordon said "In parallel, we will continue our work on the vaccine to make it more broadly effective."
TRIAL BEGAN IN 1998
VaxGen started its trial of AIDSVAX in 1998, giving volunteers seven injections over three years. It said 5,009 got at least three injections and Monday's release was based on those volunteers.
Of those, 3,330 got the vaccine and 1,679 got placebo jabs.
There had been serious doubts about how effective the vaccine would be. Many researchers believe the AIDS virus is unique because of the way it infects the immune system and cannot be battled using standard vaccine technology.
VaxGen is the first company to try. Its trial of 5,000 men and women in the United States and the Netherlands considered at high risk of becoming infected with HIV has been running since 1998.
At least 30 other AIDS vaccines are in various stages of development.
AIDSVAX is formulated to protect against the "B" strain of the virus commonly seen in Europe and the United States. It is not expected to be very effective against strains circulating in Africa, the continent hardest hit by HIV.
The company is also nearing the end of a second Phase III trial -- the last stage of testing before seeking U.S. Food and Drug Administration (News - Websites) approval -- in Thailand. This formulation is designed to protect against HIV subtypes B and E -- seen more often in Asia.
A separate study done by the U.S. Centers for Disease Control and Prevention indicated that volunteers did not increase their risk behavior during the trial, VaxGen said. The company said its analysis of the trial data suggested that everyone in the trial reduced risky behavior, such as having sex without a condom.
"If licensed, this vaccine could be an important tool to help prevent HIV infection, but it should not be considered a substitute for other risk-reducing practices," said Walter Dowdle, a former CDC deputy director who headed the data safety and monitoring board for the trial.
"HIV prevention programs will continue to be very important," Dowdle said.
ADVOCACY GROUP "DISAPPOINTED"
Many vaccines use a live but weakened virus, or a "killed" virus, to stimulate the body's immune response. But this is considered to be too dangerous to do with HIV, a retrovirus that integrates its genetic material right into the human immune system cells it infects.
AIDSVAX uses two proteins, based on the gp-120 protein found on the outside "envelope" of the virus. The hope was the body's immune system could become sensitized to anything carrying gp-120 and mount a response to the virus.
"The news on VaxGen's AIDSVAX is disappointing," Berkley said, " but we are not discouraged. The search for an AIDS vaccine will and must go on."
"Scientists remain confident that an AIDS vaccine is possible. Alternative AIDS vaccines, employing different design strategies, are now in development, and some have already entered human trials. These must move forward through further study, without delay," he said in a statement.
Berkley recommended the results on AIDSVAX be further analyzed and independently reviewed, complained about inadequate funding and praised Vaxgen for conducting the study.
"Lack of research funding continues to stymie progress toward an AIDS vaccine, and the world must step up funding. Currently, expenditures on AIDS vaccines total less than 1 percent of all health and pharmaceutical research," he said.
After praising VaxGen for "taking the first AIDS vaccine candidate through the rigors of human trials," Berkley said the company "demonstrated that a large trial of an AIDS vaccine could be completed with high retention of volunteers, and that the volunteers would not increase their risk behavior."
The Initiative is a global nonprofit organization working to speed the search for a vaccine to prevent HIV and AIDS. |
