Merck Plans to Start Phase II of AIDS-Vaccine Human Trials

[Doc L]

If everyone in this trial, whether vaccinated with the experimental HIV
vaccine or not, is engaging in safe sex, how is the true effectiveness of
the vaccine measured? If measuring antibodies is not the only important
factor in detecting a protective immune response, how will it be known if
the vaccine works? Hopefully, the HIV-free individuals participating in
these trials, who will be injected with "man-made copies of genes taken from
the inner core of the AIDS virus," are being given full, informed consent
documents detailing the adverse event and potential vaccine failure risks
associated with this experimental AIDS vaccine.


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http://online.wsj.com/article/0,,SB110658394620534090
THE WALL STREET JOURNAL
January 25, 2005

Merck Plans to Start Phase II Of AIDS-Vaccine Human Trials

Scientists to Test Prototype
Deemed Most Promising
For Safety, Effectiveness

By MARILYN CHASE
Staff Reporter

Merck & Co. said it is launching the second phase of human trials on an AIDS
vaccine that scientists called the most promising of its kind.

The prototype AIDS vaccine will be tested in 1,500 people in the U.S.,
Canada, Australia, Latin America and the Caribbean.

The Phase II clinical trial will evaluate safety and effectiveness of the
vaccine. The trial is a collaboration between Merck, the HIV Vaccine Trials
Network and the National Institute of Allergy and Infectious Diseases, a
unit of the U.S. National Institutes of Health.

The Merck trial joins approximately 50 other AIDS vaccine trials in
progress, all with the hope of halting the epidemic disease that affects
about 40 million people and killed 3.1 million in 2004.

Labeled MRKAd5, the vaccine uses an adenovirus -- a common virus that causes
colds -- as a missile armed with man-made copies of three genes taken from
the inner core of the AIDS virus. Researchers hope these three genes will
spark killer cells, known as cytotoxic T-cells, to destroy human cells
infected by HIV, the human immune-deficiency virus that causes AIDS.

"It's an exciting trial conceptually," said Lawence Corey, principal
investigator of the HIV Vaccine Trials Network. Compared with other vaccines
aimed at marshaling killer T-cells, MRKAd5 has "given the best immune
response," he said. Dr. Corey said he receives no stock or personal funding
from Merck.

This study will compare the response of volunteers given three injections of
the vaccine over six months against a control group given dummy injections.
The study is expected to last at least 4½ years, and will examine infection
rates, as well as severity of disease in the two groups. All participants
will be instructed in safe sex and other preventive behaviors.

An ideal vaccine would fight HIV two ways, by blocking infection in the
first place, and fighting any virus that sneaks in. Merck's experimental
vaccine, however, doesn't contain the gene for the virus's outer coat, a
component that would be needed to spark neutralizing antibodies that would
bar any initial infection. Still, the researchers are hoping that marshaling
the killer T-cells would be enough protection, by virtue of destroying
infected cells once the AIDS virus gets inside, to at least prevent or delay
onset of the disease.

Based on a prior Phase I safety study of this vaccine in 250 people, the
company and researchers said they believe that MRKAd5 is safe. Some
volunteers developed fevers and muscle aches that resolved in 48 hours.

This vaccine contains genes from the AIDS virus strain that predominates in
North and South America. Any successful AIDS vaccine ideally would include
HIV types found all over the world.

"Nobody," Dr. Corey said, "has given up on developing a global HIV vaccine."

Robert Belshe, professor of medicine at Saint Louis University in Missouri,
one of the testing sites, said he is optimistic because this vaccine
prevented or delayed the onset of AIDS-like disease in animals. "This is a
step forward. It's clearly not the final vaccine. We still need antibodies.
This is half the equation," he said.

Write to Marilyn Chase at marilyn.chase@wsj.com1