Nabi Biopharmaceuticals announced the successful findings from its double-blinded, placebo controlled Phase I/II trial with NicVAX (Nicotine Conjugate Vaccine), a proprietary investigational vaccine being developed to prevent and treat nicotine addiction. The purpose of this study was to assess safety and the ability of NicVAX to generate specific antibodies against nicotine following multiple injections of the vaccine. Results from the study were recently presented at the Annual Meeting of the Society for Research on Nicotine and Tobacco in Tucson, Arizona.

A total of 30 subjects comprised of 21 healthy smoking and 9 healthy non-smoking volunteers each received a series of four injections containing either NicVAX or a placebo (an inactive substance) over a six month period. The results from this study revealed that NicVAX was well tolerated and was able to generate high levels of nicotine specific antibodies. Three doses of NicVAX (administered on days 0, 14, and 28) produced significant levels of antibodies, which declined slowly over the next several months. A fourth dose (given on day 182) boosted nicotine specific antibody to even higher levels, which then declined more slowly over time. Reactions to the vaccine were consistent with those seen with other intramuscular vaccines, and tended to be mild, self limiting and resolved within a few days. The most common reactions associated with NicVAX use were localized reactions such as tenderness, aching and redness at the injection site. The most frequent systemic reactions were myalgia (muscle pain), headache and malaise (weakness).

“This trial clearly showed that multiple injections of NicVAX were safe, well tolerated and resulted in a rapid and boostable immune response that generated substantial amounts of nicotine specific antibodies which also appeared to be well tolerated,” said Henrik Rasmussen, Nabi Biopharmaceuticals senior vice president, clinical, medical and regulatory affairs. ”These encouraging results suggest that additional investigation of this vaccine as an aid to smoking cessation, to prevent the relapse in ex-smokers, and to prevent nicotine addiction in those beginning to use tobacco is warranted.”

Nabi Biopharmaceuticals is currently conducting a Phase II dose response, double-blind, placebo controlled, randomized clinical trial with NicVAX in 63 smokers at three sites in the US. The trial is designed to assess safety, specific nicotine antibody levels and trends in the rate of smoking cessation in trial participants in response to vaccination with various dose levels of NicVAX. Results from this trial are expected in the second half of 2004. This trial is funded in part by a grant from the National Institute on Drug Abuse, or NIDA, under the US National Institutes of Health.

The company previously announced results of a placebo controlled, double-blinded Phase I clinical trial of NicVAX in non-smokers. In that trial, a single dose of NicVAX produced measurable antibody levels against nicotine in all vaccine recipients as early as 7-14 days after vaccination. In addition, these antibody levels were maintained or continued to increase over 4 months. NicVAX was well tolerated and adverse events were generally mild, temporary and required no therapeutic intervention. In pre-clinical animal studies reported earlier, NicVAX generated high levels of nicotine-specific antibodies and was able to block the effects of nicotine in animals by reducing nicotine levels in the brain by up to 64 per cent.

According to the US Centers for Disease Control and Prevention, there are nearly 47 million adult US smokers. Approximately 70 per cent of these smokers want to quit and 41 per cent, or nearly 19 million people have made at least one attempt to stop smoking. However, due to the highly addictive nature of nicotine, fewer than 5 per cent of these people have been able to quit permanently. At least 1.1 billion people worldwide, a third of the global adult population, use tobacco products, which cause 4 million premature deaths annually, according to the World Health Organization. In the US, tobacco use is the single leading preventable cause of death, causing more than 400,000 deaths and generating an estimated $75.5 billion in direct medical costs and $81.8 billion in smoking-attributable productivity costs each year.