Kicking the smoking habit for good? A new vaccine may help.

By Val Willingham
CNN Medical Producer

I don't smoke. But I have a good friend who does. For years, she's been trying to quit, using patches, gum, group therapy, even exercise programs designed to help you "lose your cravings." She's gone cold turkey, smoked fake cigarettes and many times begged buddies to take her cigarettes and throw them in the trash if they saw packs in her home or car. And although she's had a few smoke-free periods in her life, she's never really quit the habit. She says it's just too hard.

Of course she's not alone. Drug experts say nicotine is more difficult to kick than heroin. Of the 44 million people in the U.S. who smoke, the American Cancer Society says, 70 percent of those smokers confess they want to quit and about 40 percent do quit each year. Yet only 4 percent to 7 percent actually give up smoking, without help, for good.

But now there may be hope. The National Institute on Drug Abuse, a division of the National Institutes of Health, has awarded Nabi Biopharmaceuticals a $10 million grant to take its anti-nicotine vaccine into phase 3 human research trials over the next few months. Called the NicVAX, the vaccine is designed to stimulate the immune system to generate antibodies that would latch on to nicotine in a smoker's body and actually prevent nicotine from ever entering the brain.

When a smoker inhales a cigarette, nicotine is absorbed through the lung tissue, into the bloodstream and carried through the body. Because nicotine is a small molecule, it easily crosses the blood brain barrier into the brain. The nicotine then binds to receptors in the brain, which release dopamine, which is a stimulant that gives the smoker a pleasurable sensation, known as a "smoker's high."

This process occurs very rapidly in the body, less than one minute after tobacco smoke is inhaled, so the nicotine fix is quick. That's what causes the addiction.

The NicVAX vaccine creates antibodies that bind to nicotine in the bloodstream, blocking it from crossing into the brain, through the brain-blood barrier. That's because these nicotine-specific antibodies are large molecules and are too big to cross into the brain. So the bound nicotine is trapped in the blood and can't reach the receptors that trigger that release of dopamine, which is what causes the pleasure response.

It's believed that the addiction of the smoker to nicotine will gradually diminish because as the antibodies created by NicVAX continue to bind the nicotine, the amount of nicotine reaching the brain will gradually decrease.

According to Nabi, these phase 3 trials could begin by the end of the year. The companys says that so far, the results have been promising with few side effects. In the phase 2 trials reports, Nabi says "a statistically significant number of participants treated with the NicVAX optimal dose were able to quit smoking and remain abstinent over the long term at rate of nearly three times that of those receiving the placebo. In addition, those participants that continued to smoke and but showed a high antibody response to NicVAX significantly reduced the number of cigarettes smoked over the full 12-month period from a baseline of 20 cigarettes per day to 10 cigarettes per day."

The vaccine will be tested over a six-month period with participants receiving a vaccine every four weeks. .The antibodies should remain in the body for a long period of time. Just how long, researchers don't know yet. Trial sites will be located across the country. You can check on clinicaltrials.gov if you're interested in becoming a participant.

I am sure my friend will be waiting to sign up.

But here's the question. Would you be willing to take a vaccine periodically to help you quit the habit? Or do you have a method that has helped you to remain smoke free? We'd like to hear.

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