Breakthrough In Experimental HIV Vaccine Prevents Infections In 31% Of Cases

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Main Category: HIV / AIDS
Also Included In: Immune System / Vaccines;  Clinical Trials / Drug Trials;  Infectious Diseases / Bacteria / Viruses
Article Date: 24 Sep 2009 - 9:00 PDT

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A phase III efficacy trial organized by the U.S. Military HIV Research Program and the Thai Ministry of Public Health, involving 16,000 volunteers in Thailand has revealed that volunteers who received a prime-boost combination of two AIDS vaccine candidates - ALVAC combined with AIDSVAX - had infection rates 31.2% lower than people who received a placebo. The two vaccines have no significant effect on HIV infection rates when used individually, but appear to be surprisingly effective when used together.

The official sponsor of this trial was the U.S. Army Surgeon General via the U.S. Army Medical Materiel Development Activity. ALVAC is made by Sanofi-Aventis, SA, France, while AIDSVAX is made by VaxGen Inc., USA.

AIVI (International AIDS Vaccine Initiative) greeted this news with excitement. IAVI President and CEO Seth Berkley, said "The outcome is very exciting news and a significant scientific achievement. It's the first demonstration that a candidate AIDS vaccine provides benefit in humans. Until now, we've had evidence of feasibility for an AIDS vaccine in animal models. Now, we've got a vaccine candidate that appears to show a protective effect in humans, albeit partially."

Wayne Koff, Senior Vice President for R&D, IAVI, said "At the very least, these results give researchers a platform on which to improve and to validate animal models and assays, and a way to attract new investment and creative energy to the field of AIDS vaccine R&D."

Berkley added, "The outcome demonstrates the vital importance of testing AIDS vaccine candidates in human trials. Because HIV causes AIDS only in humans, we can only learn so much from animal models. We could not have learned what this study is going to teach us any way other than through clinical research, and we expect to learn a great deal."

The 6-year study, which was carried out in Thailand, aimed to find out whether different infection-fighting strategies devised by Sanofi and VaxGen could be merged into a more effective attack. The study was led by Supachai Reks-Gnarm of Thailand's Ministry of Public Health.

Cate Kankins, Chief Scientific Officer, UNAIDS, said in a phone interview with Bloomberg News "What is exciting is that this has provided a proof of concept, that we can do this. Anything is possible now, it feels. It is a scientific breakthrough."

AIDSVAX contains gp120 - an HIV protein - which the virus utilizes to get into human cells. The aim is to get the human body to produce antibodies to destroy HIV before it can infect healthy cells. ALVAC utilizes a disabled canarypox virus that is designed to get the human body to produce T-cells (that seek out and destroy infection inside the body).

Michel DeWilde, R&D Senior Vice President, Sanofi Pasteur, said "Albeit modest, the reduction of risk of HIV infection is statistically significant. This is the first concrete evidence, since the discovery of the virus in 1983, that a vaccine against HIV is eventually feasible. Further work is required to develop and test a vaccine suitable for licensure and worldwide use. Sanofi Pasteur is committed to continuing to engage in public-private partnerships to drive the scientific agenda and build on this very important milestone".

Christopher A. Viehbacher, CEO, sanofi-aventis, said "HIV is bigger than any one company and country. Sanofi Pasteur will continue its long-standing commitment to HIV vaccine research and development efforts by partnering with academia, governments, non-governmental organizations, and other vaccine companies to progress the science, so that one day we will be able to provide access to HIV vaccines to people who need them."

Half of the 16,000 participants were given the combination vaccine while the other half received a placebo. All participants received counseling on HIV/AIDS prevention. Participants were checked for HIV infection twice a year for three years. By the end of the trial period 74 participants who had taken the placebo vaccine became infected, compared to 51 from the group that received the combination vaccine. The vaccine is based on B and E HIV strains. The B and E strains are more commonly found in Thailand, while the C strain is more common in Africa.

Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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