December 1, 2005

Nicotine vaccine continues to show promise

By Anne Harding

NEW YORK (Reuters Health) - Research with a new nicotine
vaccine shows that the vaccine is safe and well tolerated, with
higher doses producing a greater rate of abstinence.

"We were pleased to see that because that indicates this
vaccine does indeed have a significant impact on smoking
behavior," Dr. Dorothy K. Hatsukami of the Tobacco Use Research
Center in Minneapolis told Reuters Health. The finding of
increased abstinence, she added, was "surprising."

The next step, Hatsukami said, will be to conduct studies
to identify the optimum dose and scheduling for administering
the vaccine. She noted that the vaccine could be a useful tool
to help smokers quit, although in order to kick the habit it
will likely be necessary for them to address behavioral aspects
of smoking. "It's not going to be a miracle cure."

Hatsukami and her colleagues report results of the study in
the November issue of Clinical Pharmacology and Therapeutics.

The "encouraging results" reported in the current study, as
well as other recent research on nicotine vaccines, must be
confirmed, Dr. Jacques Le Houezec of Amzer Glas in Rennes,
France writes in an editorial accompanying the study.

The vaccine could be useful for smokers trying to quit,
former smokers hoping to ward off relapse, and could also be
used to prevent adolescents from taking up smoking, he noted,
adding that giving the vaccine to teens would raise ethical
questions as "it will be the first time that a vaccine is used
not to prevent a disease but to prevent a behavior."

The nicotine vaccine works by triggering production of
antibodies that bind to nicotine, creating a complex that is
too large to pass through the blood-brain barrier.

Hatsukami and her colleagues tested the experimental
vaccine called NicVAX in 68 smokers. This preliminary study was
designed primarily to test the safety of the vaccine.

Volunteers received placebo or 50, 100 or 200 micrograms of
the vaccine at days 0, 28, 56 and 182 and were followed for 38
weeks. They were not instructed to quit, unless they expressed
a desire to do so.

Fifty-six people completed the study.

While withdrawal symptoms and craving were considered a
potential side effect, none of the study participants
experienced these symptoms. This was likely because antibody
concentrations rose relatively slowly, Hatsukami and her team
note. There was also no sign that smokers increased their
cigarette consumption to compensate for the vaccine's effects.

Adverse effects were generally mild and were not markedly
different from those given placebo.

Six of the study participants on the highest dose of the
vaccine abstained from smoking for 30 days, compared to one on
the 100-microgram dose, none on the 50-microgram dose, and two
participants on placebo. Patients on the highest dose also took
the least time to achieve 30-day abstinence.

SOURCE: Clinical Pharmacology and Therapeutics, November