A Vaccine Against Addiction?

Scientists Report Immunizations to Treat Addiction Tantalizingly Close

Or imagine a vaccine against methamphetamines. Crack addicts would take a shot of a vaccine instead of meth and feel nothing, no high, no paranoia, no euphoria, no crash.

For nearly three decades, Dr. Kim D. Janda, a professor at the Scripps Research Institute in San Diego, has made the hunt for a simple vaccination to stop addiction his life's work. Dr. Janda envisions treatments that would work the same way as vaccinations against infectious disease. An injection would expose the immune system to small amounts of an addictive drug, and then make antibodies that would destroy it.

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And because doctors now regard drug addiction as the result of physical changes in the brain, the medical establishment has renewed interest in an immunization-based approach to one of America's leading health problems. The hope is that meth addiction and cocaine addiction will go the way of measles and mumps and become reminders of another era in public health history.

Dr. Janda's Cocaine Immunization

In January of 2011, Kim Janda and his colleagues published a paper in the medical journal Molecular Therapy about a vaccination that can stop cocaine abuse cold—at least in mice. The molecule in cocaine that acts on the brain is so small that the immune system does not recognize it. Janda and his colleagues engineered an adenovirus (the kind of virus that causes sore throats and sinus infections) so that it had cocaine grafted onto its DNA.

The doctors then gave the virus to mice. Their immune systems learned to attack cocaine the same way they attacked adenoviruses, destroying cocaine before it could reach the brain. This laboratory trial confirms the work of other researchers also searching for a cure for cocaine addiction.

The Importance of Treating Cocaine Addiction

There is no doubt that cocaine abuse is a serious health problem. Cocaine is extremely addictive. Once cocaine gets into the bloodstream, it easily passes the protective blood-brain barrier and begins to accumulate in the brain. It builds up in the reward centers of the brain such as the nucleus acumbens. It locks to receptors in brain tissues to keep them from recycling the reward chemical dopamine, so that there is a greater and greater sense of satisfaction, much like that which is derived from sex, winning at gambling, or thrill-seeking activities.

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The rush of pleasure starts just a few seconds after cocaine enters the brain, and lasts for several minutes. Most users say they have never experienced a more pleasurable feeling than that first hit of cocaine. Then users want more—and nearly 6.4 million people in the United States alone are addicted to cocaine for the high they have come to depend on. Many lose their money, their possessions, their jobs, and their families constantly seeking the euphoric high that only lasts a few minutes.

There is no step-down treatment like methadone for heroin to help people come off cocaine. And even Dr. Janda's treatment does not make recovery painless. However, an immunization to cocaine after recovery might help addicts in recovery keep from making a slip back into addiction.

Potential Vaccines for Other Addictive Drugs

Drug addiction researchers believe that it may be possible to develop similar vaccines for other addictive drugs. The concept for all of these vaccines is that they will bind to the brain-active chemical in the drug while it is still in the bloodstream outside the brain, and that the chemical that causes addicting effects will never be able to enter the brain.

Psychiatrist Thomas Kosten at the Baylor College of Medicine in Houston, Texas has been working on a different vaccine for cocaine addiction. He and his colleagues have been working on a treatment that "soaks up enough cocaine" in the bloodstream that only small amounts ever reach the brain. Unlike Janda's team at the Scripps Research Institute, Kosten and colleagues have tested their vaccine on human cocaine addicts.

The results were mixed.

The research team recruited 115 cocaine addicts from a community treatment center in West Haven, Connecticut. They randomly selected 58 volunteers to receive the vaccine and 57 volunteers to receive a placebo. All the volunteers were given 5 injections of vaccine or placebo over a 12-week period. (Five dropped out before the end of the study.) Kosten and colleagues measured antibody levels after each injection and also tested bloodstream levels of cocaine.

Just 38% of addicts who received all five injections built up antibody levels that were high enough to dull the effects of cocaine. And only about half of that 38% actually quit using the drug.

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Cocaine addicts who had received Kosten's vaccine did not get a high the next time they used cocaine. However, some cocaine addicts tried to compensate for the effects of the vaccine by using up to 10 times as much cocaine, or by buying cocaine from a variety of dealers. Some reported greater devastation to their finances after using the vaccine than before. (There is no indication that the researchers offered the cocaine addicts additional money.) About 1/4 of the volunteers who received the vaccine did not make any antibodies at all, and the effects of the vaccine seemed to wear off after 8 to 10 weeks.

Dr. S. Michael Owens has been developing a vaccine for methamphetamine abuse for InterveXion Therapies, a private biotech firm in Little Rock, Arkansas. His research takes into accounts that both "highs" and "lows" from using meth can be more severe than expected. His firm received preliminary approvals to begin clinical testing of his vaccines in 2010, and may begin testing on human volunteers in 2012.

Since drug addiction is a huge social problem, why aren't the big drug companies investing in research?

There are several strong reasons that the development of anti-addiction vaccines right now is dependent on the generosity of charitable funding organizations and the risk-taking of small biotech firms.

READ Does Your Doctor Care More About Drug Company Payoffs Than About You?

• Large pharmaceutical companies don't want to become too closely identified with drug addiction.
• There is an even larger market for treating nicotine addiction with low-tech (and mostly unreliable) medications. After all, if a medication for nicotine addiction does not work, or you don't finish the box, there is always a possibility you will buy more.
• There is a lot more profit in a treatment you have to use every day than in a treatment you only need every few months.

Immunotherapy for drug addiction faces numerous scientific obstacles. But the greatest obstacle to realizing easy treatments for addiction may be that ineffective treatment earns a lot more money.