Immunization to Block the Effects of Nicotine

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DESCRIPTION (provided by applicant): This is a response to Notice Number NOT-OD-09-058, NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications. The goal of this revision supplement is to extend our studies of nicotine vaccine efficacy in rats by introducing methods for the delivery of nicotine through inhalation of cigarette smoke. Smoking cessation medications have added substantially to our ability to treat tobacco addiction, but their efficacy is limited and new types of medications are needed. Nicotine vaccines elicit nicotine-specific antibodies which bind nicotine and alter its access to brain. Three nicotine vaccines have shown preliminary efficacy in Phase I-II clinical trials, but efficacy is closely correlated with the serum antibody titer and current vaccines do not reliably produce sufficiently high titers in all individuals. The parent grant DA10714 is using rat models of nicotine addiction to study novel means of enhancing vaccine efficacy. Like essentially all current animal studies of nicotine addiction, DA10714 models tobacco addiction using parenteral (i.v. or s.c.) administration of pure nicotine. In contrast, smokers take in nicotine by inhalation and as one of over 4,000 chemicals present in cigarette smoke. The adequacy of using such artificial dosing paradigms to model cigarette smoking is unknown and largely untested. We have adapted and characterized methods for inhalation exposure of rats to smoke simulating the smoking of 1 cigarette or periods of heavier smoking. In this revision supplement we propose to use these methods to study the effects of nicotine vaccines on the absorption and distribution of nicotine inhaled in cigarette smoke. The purposes of doing so are to 1) expand the range of preclinical models available to study nicotine vaccines, 2) assess whether inhalation models provide novel information for vaccine evaluation, 3) examine the specific role of route-specific factors such as pulmonary antibody in mediating nicotine vaccine efficacy, and 3) develop quantitative models which can be more generally used to study the contributions of the inhaled route and other smoke constituents to tobacco addiction and treatment medications development. Nicotine vaccines are an attractive initial candidate for such study because vaccination is a pharmacokinetic intervention, and accurate pharmacokinetic modeling of nicotine intake may be important in understanding and exploiting its efficacy. Aim 1 will test the hypothesis that vaccination is effective in reducing nicotine distribution to brain over a range of clinically relevant dosing conditions. Aim 2 will test the hypotheses that vaccination is more effective in reducing the distribution to brain of inhaled compared to i.v. nicotine, and that such differences are in part mediated by the presence of pulmonary mucosal or tissue antibody. Because heroin and cocaine are also often smoked, the results of this study may inform ongoing efforts to develop vaccines for these addictions as well. PUBLIC HEALTH RELEVANCE: Cigarette smoking kills 5 million people worldwide yearly. Current medications are helpful for smoking cessation but are incompletely effective. We are studying the use of a nicotine vaccine to help smokers quit, which acts by binding nicotine in blood and reducing its access to brain. Rat models of tobacco addiction use nicotine delivered intravenously, which is informative but does not accurately model the human route of intake of nicotine by inhalation from cigarette smoke. This proposal will develop and study the utility of delivering nicotine to rats via exposure to cigarette smoke, and assess whether it allows better evaluation of nicotine vaccine efficacy and can expedite its further development.