- TRENTON, N.J. (AP) - In a
disappointing setback, a promising experimental AIDS vaccine failed to
work in a large international test, leading the developer to halt the study.
Merck & Co. said Friday that it is ending enrollment and vaccination
of volunteers in the study, which was partly funded by the National Institutes
- It was a high-profile failure in the daunting quest to
develop a vaccine to prevent AIDS. Merck's vaccine was the farthest along
and was closely watched by experts in the field.
- Officials at the company, based in Whitehouse Station,
N.J., said 24 of 741 volunteers who got the vaccine in one segment of the
experiment later became infected with HIV, the virus that causes AIDS.
In a comparison group of volunteers who got dummy shots, 21 of 762 participants
also became infected.
- "It's very disappointing news," said Keith
Gottesdiener, head of Merck's clinical infectious disease and vaccine research
group. "A major effort to develop a vaccine for HIV really did not
deliver on the promise."
- Michael Zwick, an HIV researcher at Scripps Research
Institute, said the vaccine's failure is unfortunate. But he said it's
too soon to know if other vaccines using the same strategy would also fail.
- "It's par for the course in the HIV field,"
he said of the Merck result.
- The volunteers in the experiment were all free of HIV
at the start. But they were at high risk for getting the virus: Most were
homosexual men or female sex workers. They were all repeatedly counseled
about how to reduce their risk of HIV infections, including use of condoms,
according to Merck.
- In a statement, the NIH said a data safety monitoring
board, reviewing interim results, found the vaccine did not prevent HIV
infection. Nor did it limit severity of the disease "in those who
become infected with HIV as a result of their own behaviors that exposed
them to the virus" - another goal of the study.
- Merck's was the first major test of a new strategy to
prevent HIV infection. The first wave of attempts to develop a vaccine
tried to stimulate antibodies against the virus, but that hasn't worked
- The new effort - an approach that Gottesdiener said is
being tried in most other current research - is aimed at making the body
produce more of a crucial immune cell called killer T cells. The goal is
to simultaneously "train" those cells, like an army, to quickly
recognize and destroy the AIDS virus when it enters cells in the bloodstream.
- Zwick said some researchers still are working on vaccines
to neutralize the AIDS virus. He thinks ultimately what's needed is one
that combines that approach with a way to stimulate and train killer T
- Merck and the HIV Vaccine Trials Network, an international
collaboration of researchers and institutions funded by the NIH, co-sponsored
the study. The experiment, called STEP, began in December 2004 and had
enrolled 3,000 volunteers in Australia, Brazil, Canada, the Dominican Republic,
Haiti, Jamaica, Peru, Puerto Rico and the United States.
- The results announced Friday involved volunteers who
researchers thought would benefit most because they had never been exposed
to the particular cold virus used in the vaccine.
- Wall Street, on a generally upbeat day, showed little
reaction to the news, with Merck shares rising 44 cents to $51.82.
- Analyst Steve Brozak of WBB Securities said the vaccine
was considered the most promising candidate both by Wall Street and the
science community. He said a vaccine is the only financially feasible way
to fight the AIDS epidemic in poor countries and that the company that
comes up with the first successful shot would have "a license to print
- "You're talking about a Carl Sagan kind of number
- billions and billions" of dollars, he said.
- The Merck vaccine, known only as V520, also was being
tested in a similar study in South Africa and in two smaller studies, which
also were halted.
- The Merck vaccine failure is a "deep disappointment
and a scientific setback for the AIDS vaccine field," the AIDS Vaccine
Advocacy Coalition said in a statement. However, the nonprofit group added
that "while this is a disappointment, it is in no way the end of the
search for an AIDS vaccine."
- Dr. Gayle
- If one reads this article closely, and then looks at
reports of other vaccine trials, it it very clear that these vaccines DO
- The report on the Gardasil vaccine is another. Trial
participants developed precancerous lesions.
- FluMist shows the same, suppressed immune system and
- When will people get the point and accept the facts?
- Just say NO to the shots.
- Gayle Eversole, DHom, PhD, MH, NP, ND
- Founder and Director
- Creating Health Institute and The Oake Centre for natural