The world’s first attempted Aids vaccine proved a failure yesterday when, after four years’ work, the Californian biotech company VaxGen announced that trial results showed that it did not protect those at risk of HIV infection.
VaxGen did its best to put an optimistic spin on the collapse of its hopes of selling the vaccine to the US and Europe by offering the surprising finding that its AidsVax had appeared to protect African Americans and, to a lesser extent, people from some other ethnic groups.
But the 78% efficacy in black volunteers, although statistically significant, proved to be based on just 13 cases of HIV infection.
There are 42-million people in the world infected with HIV, nearly 30-million of them in sub-Saharan Africa, and the number is rising rapidly: 5m were infected last year.
There were 314 black volunteers in VaxGen’s phase III trial, which involved more than 5 000, mostly Caucasian, people in the US, Canada, the Netherlands and Puerto Rico.
VaxGen’s objective was to find a vaccine against subtype B of the HIV virus: the one prevalent in the US and Europe. In sub-Saharan Africa the main subtypes are A and C.
Seth Berkley, president of the International Aids Vaccine Initiative, said: ”It is difficult to draw conclusions about what this means.”
John Moore, a professor of microbiology at Cornell University in New York, said: ”The common sense is that this is a very small group of patients and I think they are data dredging.”
VaxGen said it intended to seek a licence to market the vaccine to those groups — African Americans and other (North American) ethnic minorities, excluding Hispanics — in whom efficacy had been shown.
”This is the first time we have specific numbers to suggest that a vaccine has prevented HIV infection in humans,” said Phillip Berman, its senior vice president for research and development and inventor of the vaccine.
But the company acknowledges that the food and drug administration, which licenses medicines, may ask for further studies to be done.
Dr Berman said a number of factors, such as behaviour, geographic location, age and sex, could account for the difference between the black and the white volunteer groups.
VaxGen said it intended to do a more detailed analysis of the trial results in the hope of finding ways to improve the efficacy of AidsVax. It is in the early stages of investigating a variation of the vaccine for the African subtype C.
IAVI and other organisations with an interest in the hunt for an Aids vaccine commended VaxGen for taking its product all the way through the clinical trials process, but made it clear that they expected the breakthrough in to come from a different direction.
”Scientists remain confident that an Aids vaccine is possible,” Berkley said.
”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.
”HIV is a tough adversary, and there will inevitably be more setbacks, but with perseverance the world will find a vaccine. Success will require the best science, and a sustained commitment, from industry, academia and government.
”Lack of research funding continues to stymie progress… ”and the world must step up funding,” he added. Spending on Aids vaccines was less than 1% of the health and phar maceutical research budget.
AidsVax is made from a protein called gp120, which lies on the surface of the HIV virus, and the intention is that it should stimulate the immune system to produce antibodies to fight the virus. Few other potential vaccines adopt this approach, except in combination with a second strategy. – Guardian Unlimited Â