01 July 2003 07:32

What was billed as the first Aids vaccine, with potential to end a global disaster that is killing millions every year, has ended with an ignominious whimper, as a Californian biotech company arranges to pull out of Thailand before the final analysis of its clinical trials involving 2 500 Thai volunteers.

Two US government health agencies and the Gates Foundation are in urgent talks about stepping into the breach. The decision of VaxGen to cut its losses could mean the loss of invaluable data to scientists working in one of the most important research areas of our time. There are lessons to be learned even from the failures of a clinical trial, said a leading US scientist yesterday.

More importantly, she said, if the western world pulled out of a trial in this abrupt way, allowing all the efforts of the Thai participants and staff to go for naught, it could wreck the chances of future clinical trials in developing countries.

"Imagine going to a developing country again and asking them to roll up their sleeves for an efficacy trial if we didn't finish this one," said Peggy Johnstone, director of the vaccine and prevention research programme of the National Institute of Allergies and Infectious Diseases (NIAID), one of the government-funded bodies considering paying the bill. "We have to consider their side of it as well. The rest of the world is looking at what happens. They are going to want guarantees."

VaxGen is acting entirely on commercial grounds. "What has happened is that their board of directors has said they are not interested in completing the trials," said Dr Johnstone. "The staff, having put blood, sweat and tears into the trial, are very interested in completing it. We are in discussions now to decide what it will need to complete the trial. From a scientific perspective, it would be a tremendous loss not to complete the trial and analyse the data."

VaxGen insisted it was not pulling out, but simply did not have the money to analyse all the data from the Thai trials. "The financial markets sent a loud and clear signal to us through the decline in our stock value and through conversations with members of the financial community. Their unambiguous response was, please do not spend more money than is necessary on your trials," said Lance Ignon, vice president of corporate communications. He said the company would announce whether the vaccine had worked this winter.

The vaccine, called AidsVax, was way ahead of the rest of the field in terms of its progress through the clinical trials designed to prove whether any drug is safe and whether it works. A phase three trial -- the last in the process -- was carried out in the US and another in Thailand.

Few expected AidsVax to be the wonder drug everybody prays for, but even if it worked in some volunteers, it would have been of use. But on February 24 this year -- at midnight -- VaxGen released the results of the US trial. AidsVax was a failure.

But, to the fury of some scientists, who accused the company of manipulation of the data, VaxGen sent a hare running, claiming that the vaccine had worked in a small minority of those who were given it, from the black and Asian communities. The most marked effect, said the company, was a 78% reduction in infection among black volunteers. However, there were only 314 of them out of a total of 5 009.

One advantage of the big US health agencies, NIAID and the Centres for Disease Control (CDC), getting involved in finalising the data from Thailand might be, said Dr Johnstone, "that we maybe avoid some of the hoop-la that happened around the American trials."

Ignon, from VaxGen, said it was now for NIAID and CDC to work out how significant the ethnic minority findings from the US trial were.

The roller-coaster ride that VaxGen has offered the Aids research community may be inevitable from a private company that has to look to the markets to fund a risky business. Don Francis, who formed VaxGen specifically to investigate an Aids vaccine, has his admirers for his determination to get involved. "It is overall disappointing that there aren't more private sector resources going into Aids vaccines, but it is understandable," said Johnstone. "Ninety per cent of the need is going to be in countries that can't pay for it."

Hype claim

Aids activists, however, point out that many scientists have argued for years that VaxGen's approach was not likely to work. "Based on the poor results from their trial here in the United States, I think they made a rational decision" to pull out of Thailand, said Gregg Gonsalves, director of treatment and prevention advocacy of Gay Men's Health Crisis in New York. "They've been hyping this vaccine for many years based on dubious data, but at some point, all the hype in the world can't salvage a product that doesn't work."

NIAID several years ago declined to give VaxGen funding for its vaccine research, he pointed out.

Richard Jefferys of the Treatment Action Group said that the decision on Thailand "speaks volumes about their confidence in the product to work", in spite of all the spin about ethnic groups in the US trial. "The positive thing about it is that they have shown that you can do a phase three efficacy trial [for an Aids vaccine]. It may be that there are unfortunately lessons about how careful people need to be in listening to the results of those trials." - Guardian Unlimited © Guardian Newspapers Limited 2003