GLOBAL: Scientists Glean Lessons from Stalled AIDS Vaccine

Important note: Information in this article was accurate in 2009. The state of the art may have changed since the publication date.

GLOBAL: Scientists Glean Lessons from Stalled AIDS Vaccine

Reuters (10.20.09) - Wednesday, October 21, 2009
Tan Ee Lyn

Further analysis has found that Merck & Co.'s failed AIDS vaccine MRKAd5 did not actually enhance volunteers' risk of HIV infection as was reported when the trial was halted in 2007, researchers announced Tuesday. Initial findings suggested that some vaccinated participants in the STEP study, such as uncircumcised men, may have been at increased risk of subsequent HIV infection.

"With ongoing follow-up, the trend in the wrong direction is diminishing," Dr. Susan Buchbinder of the San Francisco Department of Public Health told the AIDS Vaccine 2009 conference in Paris. "Either they were at risk, and that has gone away, or they were never at increased risk. It was never significant."

STEP enrolled 3,000 people from South America, the United States, Canada, and Australia, and researchers continue to monitor its participants, Buchbinder said. Among some vaccinated subjects who later acquired HIV, 29 had a slight decline in viral load for a short time, she said.

"The bigger picture issue is that we see some clues here and some clues there about ways where the vaccine may be providing some protection," Buchbinder said. "Overall it didn't protect, but we can learn something about places where the vaccine may have provided even small amounts of protection so that we can build on those."

Merck's vaccine used weakened adenovirus-5 as a vector and was designed to encourage cell-mediated immunity, using T-cells to stop or slow HIV infection. STEP continues to be important in studying the effect of such vectors on the immune system, Buchbinder said.

"We never understood the complexity of the immune system against the vector and we think that is a very important thing to understand," said Buchbinder. "Animal studies can't address that because adenovirus-5 does not normally infect non-human primates."

"These efficacy trials are really moving science forward," Buchbinder said. "With each step we are learning more information that we couldn't get any other way. We don't know what it is going to take to make a safe and effective vaccine. Each of these studies, particularly larger trials in humans, helps shine a light on issues that we didn't know or understand before."
091021
AD091809

Copyright © 2009 - Information, Inc., Bethesda, MD. The CDC National Center for HIV, STD and TB Prevention provides the following information as a public service only. Providing synopses of key scientific articles and lay media reports on HIV/AIDS, other sexually transmitted diseases and tuberculosis does not constitute CDC endorsement. This daily update also includes information from CDC and other government agencies, such as background on Morbidity and Mortality Weekly Report (MMWR) articles, fact sheets, press releases and announcements. Reproduction of this text is encouraged; however, copies may not be sold, and the CDC HIV/STD/TB Prevention News Update should be cited as the source of the information. Contact the sources of the articles abstracted below for full texts of the articles.

AEGiS is a 501(c)3, not-for-profit, tax-exempt, educational corporation. AEGiS is made possible through unrestricted funding from the Elton John AIDS Foundation, National Library of Medicine, AIDS Walk of Orange County, and donations from users like you.

Always watch for outdated information. This article first appeared in 2009. This material is designed to support, not replace, the relationship that exists between you and your doctor.

AEGiS presents published material, reprinted with permission and neither endorses nor opposes any material. All information contained on this website, including information relating to health conditions, products, and treatments, is for informational purposes only. It is often presented in summary or aggregate form. It is not meant to be a substitute for the advice provided by your own physician or other medical professionals. Always discuss treatment options with a doctor who specializes in treating HIV.

Copyright ©1980, 2009. AEGiS. All materials appearing on AEGiS are protected by copyright as a collective work or compilation under U.S. copyright and other laws and are the property of AEGiS, or the party credited as the provider of the content.