Therapeutic vaccines against tobacco addiction

Abstract

Most smokers are aware of the dangers of smoking and want to quit, yet few are successful owing to the highly addictive properties of nicotine. Available smoking cessation tools include pharmacotherapies that act in the CNS and show modest long-term efficacy. Additionally, there are emerging concerns that they may cause adverse neuropsychiatric events. Antinicotine vaccines have been used experimentally as aids to smoking cessation. It is hypothesized that antibody capture of nicotine in the bloodstream would prevent it from crossing the blood-brain barrier and reaching the nicotinic receptors. The advantage of the approach includes the relatively gradual rise of antibody levels, which may reduce nicotine withdrawal symptoms, and the possible persistence of the antibodies potentially provides long-term protection, possibly preventing relapse. Proof-of-concept studies of at least two vaccine candidates have shown correlations between antinicotine antibody exposure and smoking abstinence. Unfortunately, the only vaccine tested in two large, randomized Phase III trials, 3'-amino-methyl-nicotine r-exoprotein A conjugate vaccine (NicVAX(®), Nabi Biopharmaceuticals, MD, USA), did not demonstrate efficacy. However, despite the lack of efficacy, there is good reason for continued optimism. This review will summarize the current status of the development of nicotine vaccines, discuss possible causes for the mixed results and review future scientific directions.