Cigarette smoking kills half a million Americans each year and is the leading cause of preventable illness in the world today. Smoking harms nearly every organ in the body, compromising a smoker's general health and causing many diseases. That is because cigarette smoke contains thousands of chemicals, many of them toxic. The key ingredient underlying addiction to cigarettes is nicotine.
Drugs of abuse, including nicotine, exert powerful influences over behavior through their actions on the brain, particularly in those circuits involved in reward and motivation. Thus, any therapeutic modality aimed at preventing a drug from ever entering the brain could have tremendous addiction treatment potential. Immunization is a strategy that seems ideally suited to achieve that goal. The concept of immunizing an individual against a specific drug is an approach that has generated new interest among researchers and pharmaceutical companies. An effective anti-smoking vaccine would coax the immune system into producing antibodies that could sequester nicotine molecules in the bloodstream, keeping them from ever entering or affecting the brain. This strategy posits that if smokers find tobacco less rewarding, they can better avoid relapse once they've decided to quit.
Seven years ago, NIDA embraced this concept and decided to support and guide a major nicotine vaccine effort in collaboration with Nabi, a Florida-based pharmaceutical company. Early studies on NicVAX®, the Nicotine Conjugate Vaccine that resulted from this joint research endeavor, show it to be safe and capable of generating antibodies that block nicotine's entry into the brain. Today, results from the latest round of phase II clinical studies (on 301 heavy smokers who smoked an average of 24 cigarettes a day) show that NicVAX™ induced the production of long-lasting antibodies that helped prevent smoking relapse for up to 2 months in about a quarter of the study participants—extraordinary results for a smoking cessation trial. NIDA's support of this project is part of our continuing commitment to encourage innovative research with the potential to profoundly impact the public's health.
Our improved understanding of addiction mechanisms and of nicotine's actions as an addictive drug has been instrumental in the development of smoking cessation therapies on the market today. These include the nicotine replacement therapies, bupropion (marketed as Zyban®) and most recently varenicline (marketed as Chantix®), which are helping many smokers quit, particularly when assisted by behavioral therapies. Together with persistent and targeted public education campaigns, these advances have significantly contributed to reducing the prevalence of smoking and nicotine addiction in our Nation over the past three decades. Efforts to sustain and extend these successes must not flag, however, particularly on the heels of recent surveys revealing that the previously falling rates of adult smoking have stalled at around 20 percent, a level that foreshadows an enormous human and economic toll.
An effective nicotine vaccine would be a much-needed addition to the available toolbox of treatment options. By helping quitting smokers resist the urge to light up, this new approach could dramatically enhance the effectiveness of current treatments for nicotine addiction and improve the prospects of closing the wide gap we face in achieving the Nation's goal of reducing adult tobacco use to 12 percent by 2010.
Nora D. Volkow, M.D.
This page was last updated May 2007