VACCINE TO COMBAT ADDICTIONS SHOWS PROMISE

Scientists Report Progress Activating Immune System to Block Cocaine, Nicotine

Scientists say they are closer to developing a vaccine to treat
addiction, though it may still be several years before any drug might
come to market.

Vaccines could become a useful tool in helping treat addiction to
cocaine, nicotine and other substances. While scientists have
developed an arsenal of drugs to block cravings or to treat the
symptoms of withdrawal, vaccines would work in a completely different
way -- by activating the immune system to block the effects of
substances such as cocaine or nicotine in the body.

Producing Antibodies

To make the vaccine, scientists combine a cocaine or nicotine
derivative with a protein, such as a benign version of the cholera
toxin -- a toxic substance that, when produced during a bacterial
infection, can induce diarrhea. When a patient is injected with, for
instance, a nicotine vaccine, the body produces antibodies. Then, if a
person smokes, the antibodies will bind to the nicotine as it enters
the person's system, which prevents most of the chemical from the pure
nicotine from crossing into the brain. The nicotine then is
metabolized by the liver and secreted from the body.

Two companies using similar methods -- Nabi Biopharmaceuticals in Boca
Raton, Fla., and Xenova Group PLC of Slough, England -- are among the
furthest along in their research and have begun testing in humans.
Although the testing still is in early stages, Xenova reported in June
at a meeting of the College on Problems of Drug Dependence that early
results suggested its vaccine curbed relapse in a small group of
cocaine users.

Nabi last week reported results of a small trial of 68 smokers
conducted to test safety and to measure the levels of antibodies
produced by the vaccine. Though the protocol wasn't designed to look
for smoking cessation, Nabi said 33% of a small group of smokers who
received the highest dose of its NicVAX vaccine quit smoking, compared
with 9% in the placebo group. However, the results weren't considered
statistically significant. Both Nabi and Xenova, which have
multimillion-dollar grants from the federal government, say they don't
expect any drug to be available before 2007.

The potential market for new approaches to treat addiction is great.
The Centers for Disease Control and Prevention estimates that 46
million adults smoke, and seven out of 10 smokers want to quit. In
addition, more than two million Americans regularly use cocaine,
according to a 2003 survey from the Department of Health and Human
Services.

So far, other approaches to treating addiction that curb cravings or
treat withdrawal symptoms, have often failed, because their drawbacks
include sedation and depression, treatment experts say.

Lows of Withdrawal

What is promising about the vaccine approach, scientists say, is that
the method prevents the cocaine, nicotine or other abused substance
from reaching the brain in the first place. In theory, the addict
never gets high and doesn't face the subsequent lows of withdrawal,
either.

"You can avoid [side effects] if you keep the drug from crossing the
brain barrier," says Margaret Haney, associate professor of clinical
neuroscience at Columbia University, New York, who is a researcher in
the Xenova cocaine-vaccine study.

The vaccine wouldn't blunt cravings, but treatment experts foresee
using a combination of treatments.

A drawback to using a vaccine is that the patient would have to take
frequent injections because the antibodies aren't permanent.
Government scientists say the addict should be compared with someone
suffering from a chronic illness, such as a diabetic.

"You have to think of [addiction] in terms of being managed more than
cured," says Frank Vocci, director of the division of
pharmacotherapies and medical consequences of drug abuse for the
National Institute on Drug Abuse.