US AIDS experts: Vaccine trial cancellation is no defeat

Jul 18, 2008, 23:19 GMT

Washington - US AIDS experts on Friday said the cancellation of a promising AIDS vaccine test by a US government medical institute was not a major setback to research effort.

They were reacting to Thursday's announcement by the National Institute of Allergy and Infectious Diseases (NIAID) that it was cancelling a large human trial of a vaccine similar to one tested, then dropped, in September 2007.

The dropped vaccine had been developed by the private Merck pharmaceutical company, with some US government funds. NIAID had been planning to test a similar vaccine on 2,400 volunteers.

The development came just weeks before the August 3-8 biennial International AIDS Conference in Mexico City, which draws tens of thousands of people to push for action and learn of latest developments in prevention and treatment of the devastating disease.

Wayne Koff, director of research and development at the private New York-based International AIDS Vaccine Initiative (IAVI) who was not involved in the test project, said that such decisions belong to 'the normal process of product development.'

'Most candidates in pre-clinical development are not going to succeed,' he said in an interview with Deutsche Presse-Agentur. 'We're still somewhat in the early stages of vaccine development.'

Koff added that the experience gained from such failed attempts provides 'useful information for the overall field.'

Dr Anthony Fauci, NIAID director who cancelled the test phase of Partnership for AIDS Vaccine Evaluation (PAVE), said Merck's failed experience had shown that scientists must go more slowly because so little was still understood about the HIV virus that causes AIDS, the New York Times reported Friday.

In September, the New-Jersey-based Merck suspended its trials of a vaccine called Ad5, which was intended to lower the amount of virus in the bloodstream.

It took the step after 49 HIV infections occurred in the 3,000 people who received it, while only 33 occurred in people who got the placebo injections.

The results suggested the vaccine may have inadvertently increased HIV risk among people who were exposed to blood or semen containing the virus.

In its announcement Thursday, NIAID said the 'Merck vaccine itself did not cause HIV infection.'

Rather, the failure appeared to be connected to antibodies among males to the adenovirus - a common cold virus - that was used as the platform to deliver three of nine HIV genes into the test subjects' bodies.

NIAID said it would consider a 'smaller, more focused clinical trial designed to answer one important question: Does the product have a significant effect on HIV viral load?'

IAVI, a private nonprofit research organization which supports basic research into vaccines, supported Fauci for making a 'bold decision' in line with 'the way good scientific endeavors work.'

IAVI called for smaller studies in the future 'to test for a sign of promise before proceeding to large efficacy trials.'

'The decision by NIAID does not reflect paralysis in the AIDS vaccine field, or a lack of direction forward. In fact, it reflects the opposite. It reflects the dynamic learning that is the scientific process, that is pharmaceutical product development,' IAVI said in a statement.

More than a quarter of a century into the AIDS epidemic, 25 million deaths later, and with an estimated 33.2 million people currently living with HIV/AIDS, it is still not clear exactly how HIV causes AIDS, but there is no doubt that it does.

It is also known that AIDS is preventable, although more than 6,800 people contract new HIV infections each day. AIDS is treatable, yet 2.1 million people - more often than not, young adults in prime earning and parenting years - die each year from the disease.