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NicVAX Phase 2 Trial Demonstrates 33 Percent Quit Rate in Smokers
ROCKVILLE, Md., Sept. 28 /PRNewswire-FirstCall/ -- Nabi Biopharmaceuticals announced today positive Phase II clinical results for NicVAX™ (Nicotine Conjugate Vaccine), a vaccine that is being developed to prevent and treat nicotine addiction by acting as an aid to smoking cessation. The results indicated a 33% quit rate in smokers who received NicVAX at the highest dose level versus 9% in the placebo group. The results represented a vaccine-only effect, as patients were only given NicVAX without any supplemental treatments, behavioral support or counseling. The objectives of the study were to show that NicVAX was able to safely generate nicotine- specific antibodies in smokers, and to assess its potential use as an aid in smoking cessation among smokers who wanted to quit.
NicVAX is designed to cause the immune system to produce antibodies that bind to nicotine and prevent it from entering the brain, thereby preventing the 'rush' that occurs when nicotine binds to receptors in the brain. This 'rush' is believed to be the main physical reason that most people cannot stop smoking.
The Phase II trial was a double-blinded, placebo-controlled, randomized study in smokers designed to assess safety and antibody response. In addition, standard measures of anti-smoking efficacy, such as percentage of patients who quit smoking, was included. Conducted at three clinical trial sites across the United States, a total of 68 smokers were randomized to receive a series of up to 4 injections containing either NicVAX or a placebo. Three doses (50, 100 or 200 micrograms) of NicVAX or a placebo were administered on days 0, 28, 56 and 182. The results showed that, at the 200- microgram dose, 33% of smokers in the treated group quit smoking (defined as no smoking for at least 30 consecutive days) versus 9% in the placebo group. In addition, results showed a substantial reduction in average cigarette consumption in smokers who received the highest dose of NicVAX versus lower doses or placebo. Smoking cessation was confirmed by cotinine and carbon monoxide levels, which are biochemical markers of smoking. Nicotine dependency was measured by a questionnaire and also showed a substantial reduction at the top dose of NicVAX as compared to placebo or the lower dose levels. NicVAX was very well tolerated and side effects were similar between the active dose levels and the placebo group. The outside clinical costs for the trial were funded by a grant from the National Institute on Drug Abuse, under the U.S. National Institutes of Health.
"The vaccine-only effect that we saw in this trial is truly impressive," said Henrik S. Rasmussen, MD, PhD, senior vice president clinical, medical and regulatory affairs, Nabi Biopharmaceuticals. Dr. Rasmussen continued, "If these results could be repeated in a larger study, it would make NicVAX potentially one of the most efficacious approaches to smoking cessation available. The 33% efficacy rate that we saw at the high dose level is particularly remarkable when one takes into consideration that this was a vaccine-effect only and that psychological counseling or other behavioral interventions were not provided."
Dr. Rasmussen concluded, "We will continue to analyze the data from this study, as well as start discussions with regulatory authorities about the future development path for this compound. These additional analyses, combined with inputs from regulatory authorities and key opinion leaders in the field will help us devise the optimal development path NicVAX. However, these data clearly support the continued development of NicVAX on an aggressive time scale."
"The successful completion of our Phase II trial marks a critical milestone in the development of NicVAX and an important foundation on which to advance the drug to late-stage testing," stated Thomas H. McLain, chairman, ceo and president, Nabi Biopharmaceuticals. Mr. McLain continued, "These results are very encouraging and we believe indicate that NicVAX may represent a new paradigm in treating nicotine addiction, recognized as one of the most difficult addictions to break. In addition, since NicVAX uses the same carrier protein as StaphVAX, these results provide further proof for our conjugate vaccine technology. Using this technology we are able to help the body's immune system recognize and deal with problems it otherwise would ignore."
Full data from the study are expected to be presented at appropriate medical meetings during 2005.
NicVAX is designed to cause the immune system to produce antibodies that bind to nicotine and prevent it from entering the brain. These nicotine antibodies act like a sponge, soaking up nicotine as it circulates in the blood stream and preventing it from reaching the brain. As a result, the positive stimulus in the brain that is normally caused by nicotine is no longer present, thereby taking away the motivation for smoking, consequently helping people to quit. In January 2003, Nabi Biopharmaceuticals initiated a Phase I/II placebo-controlled, double-blinded clinical trial of NicVAX in smokers, ex-smokers and non-smokers in The Netherlands. This trial evaluated the development of specific nicotine antibody levels and safety of the vaccine in study participants. The data 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.
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The World Health Organization estimates that there are 1.3 billion smokers worldwide and nearly 5 million tobacco-related deaths each year. Of that total, tobacco use is responsible for more than 440,000 deaths each year in the US alone. According to the U.S. Centers for Disease Control and Prevention (CDC), approximately 46 million adults and 3 million high school students in the U.S. smoke, triggering an estimated $75.5 billion in excess medical costs and another $81.9 billion in mortality-related productivity losses each year. Despite widespread knowledge of tobacco's dangerous health effects, smoking continues to pose a serious public health threat, as many smokers are unable to quit, in part due to tobacco's addictive properties. According to the CDC, an estimated 70 percent of smokers in the U.S. want to quit, but less than five percent of those who try to quit are able to abstain from smoking for more than 12 months.
Source: Nabi Pharmaceuticals