AEGiS-WSJ: AIDS Vaccine Disappoints in Tests: Experimental Drug Failed To Show Robust Response In Human Immune System

Important note: Information in this article was accurate in 2004. The state of the art may have changed since the publication date.

AIDS Vaccine Disappoints in Tests: Experimental Drug Failed To Show Robust Response In Human Immune System

Wall Street Journal - September 3, 2004
Michael Waldholz, mike.waldholz@wsj.com

An experimental AIDS vaccine being tested in Africa and in the United Kingdom failed to produce a robust immune response, disappointing researchers and public-health officials who had been working on it for six years.

At an AIDS-vaccine conference in Lausanne, Switzerland, a research team from the University of Oxford and Nairobi University in Kenya reported that, in a study involving 205 volunteers, the vaccine generated a potentially protective immune system response in only about 20% of the test subjects.

Although the result comes from an interim analysis of a study that was designed to go longer, the vaccine's backers said the immune response rate was unexpectedly "poor." The non-profit International AIDS Vaccine Initiative -- which had funded the vaccine's development with about $19 million -- said that unless the data change dramatically as the study continues, the vaccine didn't merit further development.

"The response fell short of what we had expected and what had been seen in animal studies," said Emilio Emini, a research director at IAVI, which is based in New York. The vaccine was the furthest along of several vaccines IAVI is backing without commercial support.

Because the vaccine didn't generate a desired immune response, researchers said they won't conduct a human trial to test whether the vaccine can actually protect people from HIV/AIDS infection. Researchers had hoped that 60% to 80% of those tested would generate a protective immune response.

The Oxford/Nairobi vaccine was being watched closely because it is one of several that attempt to mimic the immune system of a group of Kenyan prostitutes who were found in the early 1990s to resist HIV infections despite repeated exposure to the virus. Researchers led by Andrew McMichael at Oxford found that the women had high levels of certain white blood cells, called T-cells, that were able to seek out and destroy other cells in the body infected by the virus. The new study showed that the Oxford/Nairobi vaccine stimulated a T-cell response, but at a much lower rate than desired, the researchers said.

Several other experimental vaccines, including one being tested by Merck & Co. in humans, also are designed to generate a T-cell response. These vaccines don't work by blocking the virus from infecting human cells but, instead, are designed to keep the virus under control once a person has been infected.

In a telephone interview, Dr. McMichael said he assumed some aspect of the vaccine's design was likely at fault. The vaccine is actually two separate shots. One is composed of genetic material taken from the inside of the human immunodeficiency virus; the other is made up of the genetic material stitched inside a weakened version of a virus related to smallpox called MVA. Merck's vaccine and several others wrap the genetic material inside a weakened version of an adenovirus, the virus that causes the common cold. Dr. McMichael said that approach might be preferable to using MVA.

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