Vaccine stimulates the body to produce antibodies that bind to nicotine molecules and prevent or slow them from entering the brain
A research team at the Health Sciences North Research Institute in Sudbury has had promising results with a vaccine to help tobacco smokers kick the habit.
Led by Dr. Hoang-Thanh Le, a scientist with degrees in organic chemistry from universities in Germany and France, the team is working on a vaccination strategy that stimulates the immune system to produce antibodies that bind to nicotine molecules in the airways and lungs.
The research is funded by the Northern Cancer Foundation and a $688,000 grant from the Canadian Institute of Health Research.
Normally, tobacco smoke containing nicotine is inhaled into the lungs, passes into the bloodstream, crosses the blood-brain barrier and binds to nicotine receptors, stimulating the release of dopamine.
The vaccine being developed Dr. Le and his team is aimed at sequestering the nicotine in the lungs and preventing it from reaching the brain. Deprived of the dopamine triggered by nicotine, tobacco would no longer satisfy the smoker’s physical dependence on cigarettes.
“The nicotine in tobacco is addictive and makes it difficult to quit,” said Le. “ Only a small group of people see long term success with current smoking cessation options. The nicotine vaccine would be a likely option for treatment that suppresses the addiction.”
In pre-clinical trials, mice receiving the vaccine had nicotine levels in the brain that were four times lower than those not vaccinated. Animal trials with rats are now underway and Le hopes to progress to studies with monkeys in collaboration with the Pasteur Institute in Ho Chi Minh City, Vietnam.
Researchers around the world have been working to develop a nicotine vaccine for 20 years, but without much success, said Nya Fraleigh, a member of Dr. Le’s research team.
A few vaccines had very promising pre-clinical results in animal studies, then failed in clinical trials with humans – possibly because insufficient antibodies were produced to sequester the nicotine, she said.
The vaccine being developed at the HSN Research Institute will be administered through the nose as an aerosol spray – not by injection with a needle, as was the case with NicVax, a vaccine that aimed to sequester nicotine in the bloodstream, but failed in clinical trials.
The research team hopes the vaccine administered through the nose will trigger the immune system to produce antibodies that will block nicotine in respiratory tract mucous secretions and in the lungs, explained Le. “These two lines of defence will block or at least slow the delivery of nicotine to the brain, which will reduce its addictive characteristics. Treating nicotine in the blood after its absorption in the lungs might not be sufficient or fast enough to neutralize nicotine and prevent it from reaching the brain.”
Currently, said Le, pharmacology treatments, antidepressants and nicotine replacement therapies have success rates of only 10 to 25 per cent, and several of them have harmful side effects.
Nicotine replacement therapy – available as a patch, chewing gum, inhalers and nasal sprays – don’t treat nicotine addiction. They just provide a more benign method of satisfying a smoker’s craving.
Zyban and Chantix – two pharmaceuticals available by prescription – don’t contain nicotine, but can have nasty side effects, including suicidal thoughts, hostility, depression, nausea, fainting and vision problems.
A smoking vaccine could potentially offer a safer and more effective way to deal with the physical dependence on nicotine, but psychological cravings associated with ingrained habits would still have to be overcome.
The incidence of smoking in both the North East and North West LHINs is higher than the provincial average: 26 per cent in the northeast, 23.5 per cent in the northwest, and less than 20 per cent in Ontario as a whole.
Smoking kills more than 45,000 Canadians every year from cancer, heart and lung disease.