Smoking Gene

There are a lot of ways to quit smoking: patches, gums, lozenges, inhalers, prescription pills, self-help books and many more. The proliferation of these products illustrates the simple truth that it’s very tough to quit. Smokers rarely succeed on their first try, and fewer than one-third are ever able to give up cigarettes using these available methods.

With such a low success rate, how would a smoker know which one would work the best? The answer might be in their genes.

Bupropion (marketed under the name Zyban), a popular drug prescribed to help patients quit smoking, has been shown to be more effective in people that possess certain “smoking genes,” according to a study published late last year in the journal Biological Psychiatry.

“We believe [the results] are an exciting step forward in seeking information about how one responds well to which drugs – the holy grail of personalized medicine,” said Rachel Tyndale, author of the study and professor at the University of Toronto.

These results suggest that by using genetic testing at the outset, patients can bypass some of the early false starts of smoking cessation. If they have the right genetic variant, then they know that bupropion works well for them and can tailor their treatment plan accordingly. Patients can opt for the drug before buying nicotine replacement gum or pursuing counseling options.

Tyndale’s team chose to look at the gene CYP2B6, which is associated with the body’s ability to process nicotine. They recruited 326 moderate-to-heavy smokers who smoked half a pack a day or more. The participants were divided into two groups: one that was given the standard two-month course of bupropion and another that received a placebo. The researchers monitored their progress over a six-month period.

About half of the smokers in the buproprion group had a variant of the gene CYP2B6 that made them almost three times more likely to be able to quit smoking using bupropion when compared with the placebo group. After six months, those with the smoking gene were still much more likely to have avoided cigarettes.

Smoking cessation expert Douglas Jorenby, director of clinical services at the University of Wisconsin Center for Tobacco Research and Intervention in Madison, agrees that “a major goal now… is to connect [the patients] with the correct treatment.”

While this development is a step forward, Jorenby would like to see the experiment replicated in order to verify the results.

Jorenby also had concerns that genetic testing is not yet cost-effective. Currently, the kind of genetic testing needed for this study is not commercially available, and it will be expensive when it does eventually enter the marketplace. For comparison, it costs around $2,000 to test for the breast cancer genes.

While this initial study shows hope for everyone struggling with smoking addiction, there is still a lot more to be done before its lessons can be implemented. In the meantime, Tyndale’s group is gearing up to repeat their study on this smoking gene.