Leading AIDS experts criticise major US vaccine trial

Keith Alcorn
Published: 16 January 2004

US scientists and AIDS advocates yesterday called into question the US National Institutes of Health decision to proceed with trials of a controversial vaccine strategy in Thailand, saying the $120 million needed to run the trial would be better spent on newer vaccine candidates with a better chance of success.

Writing in the journal Science, 22 leading basic scientists and vaccine researchers called on the US National Institutes of Health to review whether it is wise to proceed with the study. “We seriously question whether it is sensible now to conduct a third trial that, in our opinion, is no more likely to generate a meaningful level of protection against infection or disease,” the scientists write.

The study will use a combination of ALVAC, a canary pox-based vaccine designed to stimulate CD8+ T-cell responses to HIV, and a booster using AIDSVAX (a gp120-based vaccine designed to stimulate antibody responses). However the scientists say that both vaccines have proved weak or ineffective in studies so far. In particular AIDSVAX has failed to demonstrate any clear protective effect in two large phase III studies reported in 2003, and the authors of the letter throw particular doubt on the claim that a combination of the two vaccines might somehow stimulate HIV-specific CD4 T-cell responses.

The scientists fear that the study will fail, and warn that the cause of AIDS vaccine development cannot afford another large and costly failure.

“The scientific community must do a better job of brining truly promising vaccine candidates to this stage of development,” said Professor Michael Lederman of the AIDS Clinical Trials Unit at Cleveland University Hospitals,”otherwise we risk eroding public confidence in the research.

One of the leading AIDS advocacy groups in the United States supports yesterday’s letter to Science.

"Even if the current trial proceeded to conclusion and did show some degree of vaccine efficacy, the design of the study would make it impossible to know whether ALVAC alone was responsible, or if the addition of AIDSVAX had improved – or worsened – the outcome" said Richard Jefferys of Treatment Action Group yesterday. "A second, even larger phase III efficacy trial would then have to be performed in order to answer this question - a mind-boggling example of short-sighted planning for which the NIH should be called to task."

Further information on this website

Development and testing of vaccines - key issues in vaccine development

HIV vaccines - review of scientific approaches currently being followed in vaccine development

Vaxgen announces second phase III trial failure in its AIDSVAX programme - news story November 2003

HIV vaccine fails in first large trial; may protect Blacks, Asians only - news article, February 2003

More scepticism than enthusiasm for VaxGen claims on race and AIDS vaccine response - news article, February 2003

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