New vaccines may target our bad habits
CHICAGO – Vaccines, the most potent medical weapon ever devised to vanquish deadly germs, are now being called on to do something totally different and culturally revolutionary: inoculate people against bad habits like overeating, cigarette smoking and drug use.
Whether this new era of vaccine research can actually subdue many of the poor lifestyle choices that are today’s biggest threats to health – causing obesity, cancer, heart disease and other problems – has yet to be proved.
But the evidence is promising enough to persuade the federal government to put millions of dollars toward finding out if two of the vaccines can end nicotine and cocaine addiction.
The National Institute on Drug Abuse, which has spent $15 million on clinical trials for the vaccines and plans to spend more, predicts that one of the nicotine vaccines may be available for marketing in three years.
“The American Cancer Society has projected that we will have one billion people die from smoking in the world in this century,” said Frank Vocci, director of medications development for the institute. “If you had a vaccine that helped people quit and stay quit, or prevent them from smoking, that’s where you’d get the greatest public health benefit.”
Meanwhile, results from a major obesity vaccine trial under way in Switzerland are expected later this year and company officials are hopeful that the vaccine could be ready for use in a few years if all goes well.
To tamp out deleterious behavior, the new vaccines employ the body’s natural immune system in an innovative way. Instead of building antibodies to destroy germs as traditional vaccines do, they construct antibodies that lock onto nicotine and cocaine molecules, preventing them from reaching the brain.
“What we’re seeing is a renaissance in vaccine technology,” said Dr. Gary Nabel, director of the National Institute of Allergy and Infectious Diseases’ Vaccine Research Center. “It’s only natural that when you have a technology that’s this powerful it can be applied to other medical problems.”
Normally, nicotine and cocaine molecules are too small to be seen by the immune system. So to make the vaccines, scientists attach these molecules to big target proteins, like harmless viruses or bacteria, which the immune system can recognize and attack with specialized antibodies.
In the case of the obesity vaccine, antibodies attach to the hunger protein called ghrelin, preventing it from reaching the brain and stimulating appetite.
Ghrelin, which is secreted by the empty stomach, travels in the bloodstream to the brain, where it tells a person to eat. But the hormone, discovered in 1999, also has other important roles, such as signaling the body to become less active and to store food as fat instead of using it for energy production.
The reason it can be so hard to lose weight, researchers believe, is that dieting causes large amounts of ghrelin to be produced as the body seeks to stimulate eating, slow down the metabolism of fat and promote fat retention.
To many researchers the vaccines seem to be a potential answer to some of society’s major ills – in the U.S. there are 50 million cigarette smokers, 5 million drug addicts, 60 million obese adults and 9 million overweight youngsters between the ages of 6 and 19.
Most have one thing in common: They’d like to quit but can’t. Nearly seven of 10 smokers, for instance, say they want to stop, but up to 90 percent of those who try to quit resume smoking within a year. The relapse problem is even worse for cocaine addicts.
“There is a great deal of promise for the nicotine vaccine not only as a smoking cessation tool but also potentially as a relapse prevention tool,” said Dorothy Hatsukami, director of the Transdisciplinary Tobacco Use Research Center at the University of Minnesota Cancer Center.
Hatsuakmi’s preliminary data showed that in a small group of smokers the nicotine vaccine enabled 38 percent to remain abstinent for 30 days compared with 9 percent on a placebo.
The goal is getting people to give up cigarettes for a year. “If you can get someone past 12 months with being smoke free there’s a 70 to 75 percent chance that that person will remain smoke free,” said Nabi official Thomas Rathjen.
Unlike most older vaccines, which tend to confer permanent immunity, the new breed of vaccines is reversible, providing immunity against nicotine, cocaine or the hunger hormone ghrelin for one to three months before booster shots are needed. So far, none of the lifestyle vaccines has produced side effects other than some flu-like symptoms and soreness at the injection site.
“These vaccines are not going to be a panacea for treating everything,” said Kim Janda of the Scripps Research Institute, a pioneer in developing vaccines for addiction and obesity. “I believe they can be helpful. When people are undergoing abstinence for drugs of abuse and they have weak moments, if you have a vaccine in place it can assist them so they don’t spiral down to ground zero.”