Nabi announced that the U.S. Patent and Trademark Office has issued U.S. Patent No. 6,232,082, entitled "Hapten-Carrier Conjugates for Treating and Preventing Nicotine Addiction." The patent covers the binding of nicotine to a protein carrier for use as a vaccine for treating and preventing nicotine addiction, the technology behind Nabi's investigational vaccine, Nabi NicVAX.

David Gury, Nabi's Chairman, President and CEO, said, "The issuance of this patent solidifies our proprietary position around NicVAX and provides further momentum to our product development efforts. Nicotine addiction is an important health concern in the United States, and while 80 per cent of smokers express a desire to quit smoking, fewer than 10 per cent of those who try succeed for more than six months. Thus, we believe this product has the potential to meet a major healthcare need."

The patent specifically covers the composition of stable nicotine-carrier protein conjugates that preserve the natural structure and orientation of nicotine, with the result that antibodies are generated specifically to the native form of nicotine. Clinical trials will be required to determine if these antibodies are effective in binding nicotine that is inhaled from smoking, absorbed from smokeless tobacco or otherwise ingested. The patent furthermore covers the method of using nicotine-protein conjugates as a vaccine to treat and prevent nicotine addiction in patients.

Nabi has demonstrated the ability of NicVAX to generate high levels of nicotine-specific antibodies in vaccinated animals and has shown that these antibodies quickly bind free nicotine in the blood. Research has further demonstrated that the nicotine-antibody complexes are too large to cross the blood/brain barrier, and thus less nicotine reaches the brain of a vaccinated animal after intravenous nicotine administration.

Nabi will test clinically the possibility that the immune barricade can prevent nicotine from inducing its physiological and psychological effects in the brain. One of the potential targets of a nicotine vaccine is preventing positive feedback from nicotine should tobacco users, who are trying to break their habit, be exposed to nicotine.

Nabi has also shown in animals that antibodies induced by the vaccine can significantly reduce nicotine addiction and nicotine levels in the brain compared to that seen in control animals. These studies also show that the vaccine can prevent nicotine-induced blood pressure increases, and attenuate hyperactive movement in response to nicotine injections.