Nicotine Vaccine Shows Promise
The world’s 1.3 billion smokers could eventually have a powerful new way to kick the habit -- a vaccine against nicotine.
Nearly 60% of smokers who achieved high levels of antibodies against nicotine after receiving the vaccine stopped smoking for at least six months, according to a study presented Saturday at a meeting of the American Society of Clinical Oncology in Orlando, Fla.
About a third of those who developed lower levels of antibodies stopped smoking, about the same fraction as those who received a placebo vaccine, according to Dr. Jacques Cornuz of Centre Hospitalier Universitaire Vaudois in Lausanne, Switzerland, who led the study.
“The data clearly suggest that antibodies against nicotine are effective in helping people quit smoking,” Cornuz said in a telephone interview after he delivered the paper. “This confirms the concept of vaccination” against smoking.
About a third of those who received the vaccine achieved the highest levels of antibodies. Before the company that makes the vaccine used in the study can begin larger clinical trials, Cornuz said, it will have to find ways “to intensify the immunization scheme” so that more people achieve the necessary antibody levels.
That may mean more injections, he said, or higher levels of the immunizing agent in each dose. He estimated it would be as long as three years before new trials could begin.
Dr. Roy Herbst of the M.D. Anderson Cancer Center in Houston said he found the results intriguing. “The best way to help patients is to prevent them from getting cancer in the first place,” he said. “I find it very encouraging that there is something to treat the addiction.”
Smoking is thought to be the cause of 30% of all cancer deaths and 87% of deaths from lung cancer.
But tobacco is very addictive -- more so than cocaine and heroin, according to some researchers. There are a variety of prevention tools available to combat smoking, including nicotine patches, nicotine gums and drugs such as bupropion.
“But there are groups of patients who fail all these therapies,” Herbst said.
At least four companies are testing nicotine vaccines: Cytos Biotechnology of Zurich, whose vaccine Cornuz studied; Xenova Group of Berkshire, England; Nabi Biopharmaceuticals of Boca Raton, Fla.; and Prommune of Omaha, Neb.
The concept behind the vaccines is simple. Antibodies to nicotine bind to it in the blood and remove it, preventing the drug from reaching and stimulating the brain.
“We’re basically taking away the positive reinforcement, which is the main reason people can’t stop smoking,” said Dr. Henrik S. Rasmussen, a senior vice president of Nabi.
Nicotine itself is too small to provoke an immune response in the body. The companies get around this by attaching nicotine molecules to much larger proteins or synthetic compounds that do stimulate a response.
In the current trial, Cornuz and his colleagues enrolled 341 patients at three Swiss hospitals. Two-thirds of them were given the experimental vaccine in five doses over a four-month period. The rest were given a placebo.
About a third of the subjects were not included in the final analysis because they also used a nicotine replacement, either gum or a patch, which would confuse the results, Cornuz said.
Of the 53 patients who developed the highest levels of antibodies, 30 stopped smoking, and those who didn’t smoked fewer cigarettes, he added. Researchers relied on subjects’ reports of smoking and on measurements of carbon monoxide levels in the blood, a conventional measure of smoking activity.
