Trial Drug May Help Smokers Kick Butts

CNN News Wire | 11/9/2009, 9:43 p.m.
When Katherine Frazier was a teenager in Silver Spring, Maryland, back in the '60s, smoking was the "in" thing to ...

Fast-forward 40 years. Frazier, 57, still smokes, but she wants to quit. She knows that the longer she puffs, the higher her risk for developing certain health problems, including heart disease and certain cancers.

In her battle against the butt, Frazier has stuck on patches, chewed gum and even tried going cold turkey. Sometimes it worked, but never for long. "I am desperate to quit smoking for good," she said.

Soon, she might have another tool at her disposal.

The National Institute on Drug Abuse, a division of the National Institutes of Health, gave Nabi BioPharmaceuticals a $10 million grant to take its anti-nicotine vaccine, NicVAX, to Phase III clinical trials.

According to the National Institutes of Health, in Phase III trials, the treatment is "given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely." It's also the last step before the drug can go before the FDA for approval.

NicVAX is designed to stimulate the immune system to generate antibodies that latch on to nicotine in a smoker's body and actually prevent nicotine from ever entering the brain. The testing began last week.

"Nicotine addiction causes nearly a half-million deaths annually in the United States alone. Finding effective treatments that can help people stay off cigarettes has been a real challenge," NIH Director Dr. Francis Collins said. "This Phase III trial of a nicotine vaccine offers tremendous hope towards solving this immense public health problem."

Drug experts say nicotine is more difficult to kick than heroin. The American Cancer Society reports that of the 44 million smokers in the United States, 70 percent say they want to quit. About 40 percent do quit each year, but only 4 to 7 percent manage to give up smoking, without help, for good.

"We hope the Phase III trials will get stronger results so that a large percentage of our population can benefit from it," said Dr. Nora Volkow, director of the National Institute on Drug Abuse. "Ideally, we'd like to see 100 percent of those taking the vaccine stop smoking for good."

Volkow says that what makes NicVAX different from existing anti-smoking therapies is that it helps smokers quit permanently. Relapse is a significant challenge facing smokers, and relapse rates with currently available smoking cessation therapies can be as high as 90 percent in the first year after a smoker quits, Volkow says.

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

The whole process occurs very rapidly -- less than one minute after tobacco smoke is inhaled -- so the nicotine fix is quick, reinforcing the addiction.

The NicVAX vaccine prompts the immune system to create antibodies that bind to the nicotine molecules in the blood. The now-larger molecules are prevented by their size from crossing the blood-brain barrier. Trapped outside the brain, the bound nicotine can't reach the receptors that trigger the release of dopamine. No dopamine, no pleasure.