VACCINE TESTS TO PREVENT COCAINE ADDICTS' RELAPSE

New York scientists are testing an experimental vaccine that could help
fight cocaine addiction. If it's proven effective, it could help prevent
former cocaine users from relapsing.

Historically, vaccines have been developed to prevent disease by exposing
the body to snippets of the infecting agent, which allows the body's immune
system to mount a defense against the disease. The antibodies formed during
this process act like soldiers guarding against invasion.

But recently, a different vaccine approach has emerged. Again, the theory is
based on the body's calling upon the immune system for help. This new
approach is based on the antibody's ability to block cocaine as it enters
the bloodstream on its way to the brain, where it triggers euphoria. About
500,000 Americans are addicted to the powerful stimulant. About 2 million
others are occasional users.

The cocaine molecule is small and can easily sneak into the body without
letting the immune system know it's present. In vaccine development,
scientists attached the cocaine molecule to a larger molecule, and thus were
able to generate an immune response - antibodies - which proceeded to mop up
cocaine in the bloodstream before it got to the brain.

Scientists say the vaccine is designed to prevent relapse and would probably
not work to stop cocaine use.

"It doesn't affect the craving for cocaine," explained Dr. John St. Clair
Roberts, medical director of Xenova Group, a biotech company in England.
"But it can prevent reinforcement of the craving." For the former addict "it
means that if they fall off and take a snort of cocaine, it would neutralize
that slip."

A small number of human addicts has received injections of the vaccine in a
test of its safety. A study now under way at Columbia University College of
Physicians and Surgeons will test how well it works.

The study is being run by Margaret Haney, associate professor of clinical
neuroscience at Columbia. Haney worked closely with the late Marian
Fischman, who in the late 1980s created one of the country's first 24-hour
cocaine research laboratories at Columbia.

Volunteers in the study will be given cocaine under strict laboratory
conditions and then receive four injections over eight weeks. At 12 weeks,
they will be given cocaine again in an effort to determine if the vaccine is
effective.

The scientists have permission from the Food and Drug Administration to
study 10 patients. "We expect the changes [in the experience of pleasure] to
be significantly reduced after vaccination," St. Clair Roberts said. The
study will be completed within a year.

But some cocaine researchers worry that users will learn how to overcome the
antibody response.

"We'll certainly need many different ways to help cocaine addicts," said Dr.
Nora Volkow, associate lab director for life sciences at Brookhaven National
Laboratory in Upton. Next month, Volkow becomes the new director of the
National Institute on Drug Abuse, which is funding the study. "The vaccine
by itself will not be sufficient."

That's because cocaine is a powerful stimulant that turns on the brain's
dopamine cells, which signal that something is pleasurable. Cocaine works
directly on these cells, Volkow explained.

The British scientists developing the vaccine admit that it's not likely
that the treatment would block all cocaine in the bloodstream from getting
into the brain.

"It's an interesting strategy," said Michael Kuhar, the Chandler professor
of pharmacology at Emory University in Atlanta. He has been studying cocaine
for decades and has discovered about 500 molecules that look like cocaine
"but are more selective, more potent or slower to get into the brain," he
said.