Dorothy Hatsukami, Ph.D., director of the University of Minnesota Cancer Center's Transdisciplinary Tobacco Use Research Center (TTURC), is the lead author on this study. The 38-week study included 68 active smokers who were randomly assigned to receive one of three different doses of the vaccine or a placebo. The findings are published in the current issue of the journal Clinical Pharmacology and Therapeutics.
"The vaccine works by producing antibodies that specifically bind to nicotine and thereby prevent much of the nicotine from entering the brain," Hatsukami said. "This process potentially reduces the pleasurable effects from smoking and reduces the addiction to nicotine."
The vaccine may become a new option for helping the approximately 45 million people in the United States who smoke. In 2004, the rate for smoking in Minnesota was about the same as the national average of 20.9 percent.
"More research needs to be done, but at this point, our results show the vaccine is safe and well-tolerated," Hatsukami said. "We found the vaccine has few side effects on the central nervous system because the antibody itself is targeted specifically for nicotine and does not alter any functions of the brain."
Additionally, she says that while this study was not designed to test the treatment effect, 38 percent of the participants in the high-dose vaccine group quit smoking for at least 30 days.
"This result was an impressive and completely unexpected finding because the study was not focused on helping smokers quit smoking," she noted. "In fact, to participate in the study, smokers had to attest that they did not have a planned quit date for the next six months."
Cigarettes are linked to a number of diseases, the leading being lung cancer which is the number one cause of cancer-related deaths in the United States and in Minnesota. This year in the United States, more than 170,000 people will be told that they have lung cancer and 160,000 will die from it. In Minnesota, more than 2,600 residents will be diagnosed with lung cancer this year, and nearly 2,500 people will die from it.
Hatsukami conducted this study in collaboration with researchers at the University of Wisconsin and University of Nebraska. This study was sponsored by the National Institute of Drug Abuse and Nabi Biopharmaceuticals, developer of the NicVax vaccine. Paul Pentel, M.D., with Hennepin County Medical Center in Minneapolis, previously evaluated the vaccine in rats and found that the vaccine-induced antibodies led to reduced levels of nicotine in the brain. His research also showed that the nicotine-vaccinated rats reduced their intake of nicotine compared with rats not given the vaccine. Those results led to testing the vaccine in humans. This study reported by Hatsukami is the latest in several Phase 1 and 2 human clinical trials.
According to Hatsukami, the most commonly reported side effect was an ache and tenderness in the area of the arm where the vaccine was injected. Some of the participants also reported headaches and muscle pain, which in all cases went away in a few days.
"No differences were noted in withdrawal symptoms between participants who received the vaccine and those who got the placebo," Hatsukami said. "We also did not see a compensatory smoking behavior, meaning that vaccinated participants did not puff harder on cigarettes or smoke more cigarettes to make up for the lower levels of nicotine delivered to the brain." More research is required because other questions about the vaccine need to be answered, such as how long the effectiveness of the vaccine will last for a smoker and whether the vaccine can be used to prevent people who quit from relapsing and starting to smoke again.
"Our findings add to scientific information about nicotine vaccine and provide the basis for additional research to answer those questions," Hatsukami said.