Thailand rejects criticism of AIDS vaccine trial; thousands to test over next two years

Friday, January 16th 2004, 12:00 am

By: News On 6

BANGKOK, Thailand (AP) _ Thailand on Friday dismissed criticism by American HIV researchers that a massive test of a possible AIDS vaccine on thousands of healthy Thais would fail, saying the U.S.-funded trial still has hopes of breaking new ground.

Twenty-two leading U.S. HIV scientists alleged that the 16,000 Thai volunteers who were expected to receive a shot over the next two years will receive a cocktail made of two antiquated AIDS drugs, each of which failed previous human tests.

The researchers, including a co-discoverer of the AIDS virus, Robert Gallo, also said the U.S. government was wasting $119 million by funding the experiment. They made the allegation in a signed opinion article published in Friday's issue of the U.S. journal Science.

``We admit each drug by itself doesn't work, but that's why we started this project _ to see if the combination could work,'' said Dr. Prasert Thongcharoen, chairman of the Thai National AIDS Commission's subcommittee on HIV Vaccine Development.

Prasert said the trial underwent strong technical and ethical scrutiny by more than 11 committees that included both Thai and American researchers.

The teams considered canceling the trial after the failure of a smaller test by Bangkok authorities, but in discussions at a UNAIDS and Communicable Disease Control forum in Geneva last year, ``everyone agreed we must go on to learn exactly what could happen,'' he said.

The earlier trial, which began in 1999 and was declared a failure last year, was conducted with 2,500 Thai drug addicts and used only the trial vaccine AIDSVAX.

Prasert lashed out at the U.S. scientists for criticizing the current trial, saying the experiment is ``a must'' and is ``the only way'' to understand whether the drug combination is effective.

``I don't think this is waste of time,'' he said, noting that Thailand has the E-type strain of the virus, which few other countries have. ``Who will do that trial for us if we don't do it?''

Kamol Uppakeow, head of the local support group Thai Network for People Living with HIV/AIDS, said researchers should not abandon the trial based on the unfavorable results of past experiments.

``This trial is important,'' she said. ``You can't stop trying just because similar studies in the past didn't work. This project must go on. We can't be afraid of failures.''

The trial is being conducted in the southeastern provinces of Chonburi and Rayong, where new infection rates are between 70 to 80 people daily _ equivalent to the national average.

Volunteers are men and women between the ages of 20 and 30, some of whom are at high risk of infection because they live with HIV-positive people. The purpose of the trial is to see how the combined drugs work in people living among HIV/AIDS patients.

Last year, AIDSVAX, created by California-based VaxGen Inc., also failed to protect volunteers against the disease in a 5,400-person North American trial.

Since then, VaxGen essentially has abandoned its pursuit of an AIDS vaccine.

Despite those failures, AIDSVAX is one of the drugs being used in the current trial. It's the second part of a one-two punch that supporters see as the most promising approach to defeat the AIDS virus by provoking several different immune responses.

A VaxGen spokeswoman declined comment.

The ``prime'' piece of the Thai cocktail is ALVAC, created by Aventis Pasteur. An Aventis scientist defended the drug as worthy of continued development.

But critics argue that the U.S. National Institutes of Health scrubbed a U.S.-based trial with the same two-part cocktail two years ago because of failures in a smaller experiment.

The U.S. trial targeted a different AIDS strain than the Thai test and was more narrowly focused. Still, the 22 scientists said the two tests are similar enough to warrant cancellation of the Thai experiment.

Researchers already have administered the cocktail to about 500 volunteers since the experiment began in September and plan to give shots to 15,500 more people over the next two years. It will take about five years to see results.

U.S. government officials and advocacy groups contend the failed VaxGen drug has shown promise when used in combination with the Aventis drug in smaller experiments. More elaborate experiments are needed to prove whether the combination is effective, they say.