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Trial drug may help smokers kick butts

By Val Willingham, CNN Medical Producer
The release of dopamine in the brain generates the pleasurable sensation known as a "smoker's high."
The release of dopamine in the brain generates the pleasurable sensation known as a "smoker's high."
STORY HIGHLIGHTS
  • Drug maker given $10 million grant to take anti-nicotine vaccine to Phase III clinical trial
  • "Smoker's high" comes from release of dopamine in brain, triggered by nicotine
  • NicVAX stimulates immune system to prevent nicotine from entering brain
  • In theory, it would help smokers quit for good by reducing pleasure

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(CNN) -- When Katherine Frazier was a teenager in Silver Spring, Maryland, back in the '60s, smoking was the "in" thing to do. She thought it was glamorous. She thought it was cool. Her friends smoked, her parents smoked, and at the time, no one knew that smoking tobacco could kill you.

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.

Video: Vaccine trial underway
Nicotine addiction causes nearly a half-million deaths annually in the United States alone.
--Dr. Francis Collins

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."

MayoClinic.com: Nicotine dependence

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.

MayoClinic.com: Secondhand smoke

If I could quit, it would be a huge goal in getting my health in order. This could change my life.
--Kimberly Frazier
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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.

It's believed that a smoker's addiction to nicotine will diminish over time because, as the antibodies created by NicVAX continue to bind to the nicotine, the amount of nicotine reaching the brain will gradually decrease. This lack of feel-good reinforcement reduces the urge to continue smoking.

According to NicVAX maker Nabi, the results of prior trials have been promising, with few side effects. In the Phase II trials, Nabi reported that 30 percent to 35 percent of those given NicVAX were able to remain smoke-free over the long term, compared with only 10 percent of those receiving the placebo.

"In addition, those participants that continued to smoke 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," Nabi reported.

The initial Phase III study for NicVAX will enroll approximately 1,000 patients. The primary reason for the study is to see what the abstinence rate is at 12 months: in other words, how many people are actually quitting for good? Study results are anticipated in the third quarter of 2011. According to Volkow, that's when "we can get the vaccine in front of the Food and Drug Administration for approval."

If you're interested in participating in a clinical trial, including NicVAX, click here

Frazier is thinking about joining the trial. But for now, she's relying on her own willpower to cut down on the number of cigarettes she smokes per day. Eventually, she knows she's gong to need some help.

"If I could quit, it would be a huge goal in getting my health in order. This could change my life," she said.

 
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