Trial nicotine vaccine may help prevent smoking addiction, relapse

Oregon Health & Science University is among 22 centers participating in a Phase III clinical trial to determine whether a new investigational smoking cessation aid called NicVAX is safe, effective and capable of stimulating an immune response, the school announced Feb. 3.

OHSU was one of nine centers to participate in the earlier Phase II trial of NicVAX, a proprietary investigational vaccine developed by Nabi Biopharmaceuticals.

Nicotine is a mind-altering compound that easily crosses the blood brain barrier, a network of blood vessels that makes it difficult for toxic substances to enter the brain. Because nicotine molecules are extremely small, they don’t stimulate an immune or antibody response by themselves. Once in the brain, nicotine binds to specific receptors that trigger the release of several neurotransmitters, such as dopamine, that change the way the smoker feels.

“Smokers continue to smoke even when they know it’s harmful because of these ‘brain effects,’” explained David Gonzales, OHSU principal investigator and clinical investigator in medicine (pulmonary and critical care medicine) at the OHSU Smoking Cessation Center, OHSU School of Medicine.

“NicVAX is designed to block nicotine before it enters the brain,” Gonzales said.”

The vaccine stimulates the body’s immune system to produce antibodies that bind to or capture the nicotine molecules in the bloodstream, creating a complex that is too large to cross the blood-brain barrier. As a result, many of the expected rewards from smoking are blocked, making it easier for the smoker to become and remain abstinent.”

Because antibodies circulate in the bloodstream for an extended period of time, researchers hope the vaccine also will help smokers maintain long-term abstinence from cigarettes.

Because a vaccine is not a drug and not metabolized, Gonzales said, there is no expected risk of vaccine/drug interactions. Should the results of the study demonstrate that the vaccine is safe and effective and the Food and Drug Administration grants approval, some smokers may be able to use a cessation aid for the first time.

Approximately 1,000 male and female smokers ages 18 to 65 will take part in the study for a 12-month period; about 50 will be enrolled at OHSU. Half of study participants will receive the vaccine and half will receive a placebo.

At the end of the 12-month observational period, Gonzales and his colleagues will evaluate participants’ overall abstinence based on self-reported cigarette use and exhaled carbon monoxide.

In addition, the researchers will assess the safety and immune system response to NicVAX at various intervals throughout the study and determine whether the vaccine has an effect on withdrawal symptoms, cigarette consumption, smoking satisfaction and nicotine dependence.

Smokers interested in learning whether they qualify for study should call 503-494-0503.

This study is funded in part with a $10 million grant from U.S. National Institute on Drug Abuse, part of the National Institutes of Health.

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