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Addiction

Researchers develop vaccine to treat nicotine addiction

 

Researchers have developed a vaccine that successfully treated nicotine addiction in mice, according to a study published Wednesday in Science Translational Medicine.

With just a single dose, the vaccine protected mice against nicotine addiction for the rest of their lives, the researchers said.  The vaccine works by prompting the animal’s liver to act as a ‘factory’ that continually produces antibodies.  The antibodies then absorb the nicotine as soon as it hits the bloodstream, preventing it from reaching the brain or the heart.

According to the study’s lead investigator, Dr. Ronald Crystal, chairman and professor of Genetic Medicine at Weill Cornell Medical College, it normally takes nicotine about six to 10 seconds to cross the bloodstream, reach the brain and bind to receptors.  This is what produces the calm or relaxed feelings that drive nicotine addiction.  By blocking nicotine from reaching the brain, the antibodies prevent those pleasurable feelings from occurring.

"As far as we can see, the best way to treat chronic nicotine addiction from smoking is to have these Pacman-like antibodies on patrol, clearing the blood as needed before nicotine can have any biological effect," Crystal said in a released statement.

Importantly, the vaccine allows the body to build up its own immunity against nicotine, making it more effective and consistent than vaccines developed in the past.  

Crystal said previous nicotine vaccines likely failed because they directly injected nicotine antibodies into the body, rather than prompting the body to build its own antibodies.  This meant these ‘passive’ vaccines had to be injected multiple times, because they only lasted for three to four weeks, and the dosage level required may have varied from person to person—particularly if the person started smoking again.

On the other hand, the researchers knew the second main type of vaccines, known as ‘active’ vaccines, wouldn’t protect against nicotine addiction either.   Active vaccines—used to protect people against viruses such as polio or the mumps—work by introducing a piece of a virus into the body, which in turn prompts the body to develop a lifelong immune response against the invading agent.  However, nicotine molecules are too small for the immune system to recognize.

As a result, the researchers had to develop a third kind of vaccine: a genetic vaccine, which works by binding the genetic sequence of a nicotine antibody to a non-harmful virus.  The virus is directed to go to the liver cells, and the genetic sequence of the antibody then inserts itself into those cells, causing the cells to produce a stream of the antibodies along with the other molecules they make.

“We can target almost any organ [with this type of vaccine], but the reason for using the liver is that it is a very good secretory organ,” Crystal told FoxNews.com.  “The liver is very good at making and secreting many proteins, so we just genetically modified the liver cells to also make antibodies against nicotine.”

Crystal said he first thought of the concept behind the vaccine a few years ago while passing by a newsstand.  “I saw a magazine cover that said something along the lines of ‘Addiction: We Need Vaccines’ and got this idea to use gene therapy.”

The vaccine doesn’t appear to have any negative side effects, though it still must be tested in rats and non-human primates for efficacy before it reaches human trials.  Crystal said if the vaccine continues to show promise in animal trials, it will likely be tested in humans in the next two years. 

Furthermore, if there is proof of both safety and efficacy, the vaccine could even potentially be used as a preventative measure in the future, similar to the HPV vaccine, Crystal added.  The concept could also theoretically be used to develop vaccines for other drug addictions, such as cocaine and heroin.

Approximately 20 percent of Americans smoke, despite taxes, warning labels and television advertisements warning against the dangers of cigarettes and their associated negative health effects—such as lung cancer, emphysema and COPD.  These diseases are responsible for one in every 5 deaths in the U.S.  Seventy percent of people trying to quit end up relapsing within six months.

“It’s an addiction—it’s very hard to stop and enormously costly to society,” Crystal said.  “We need new strategies to help people get past this addiction, and this is a promising, novel approach, so we’re hopeful.”