New Haven, Conn. -- A therapeutic cocaine vaccine designed to suppress the high addicts get from taking cocaine is safe and produced cocaine antibodies in humans, a Yale study finds.
Thomas Kosten, M.D., principal investigator on the phase 1 study, and his team administered the vaccine to 34 former cocaine abusers living in a residential treatment facility.
The vaccine, TA-CD, is designed to generate drug-specific antibodies, which bind to cocaine and prevent it from traveling to the brain from the bloodstream. This neutralizes its psychoactive effect.
"The vaccine is very safe and we did not observe any major side effects," said Kosten, professor of psychiatry at Yale School of Medicine. "TA-CD was effective in producing cocaine-specific antibodies, which lasted throughout the trial. More advanced trials are already underway. TA-CD offers the potential for a completely new and highly viable approach to a very serious problem for which there are no alternative therapies available."
Such a product, Kosten said, would be complementary to behavioral therapy in overcoming cocaine addiction. This vaccine would target the more than two million regular cocaine users in the United States alone. Of these, 900,000 seek treatment each year.
In the Phase 1 trial, the vaccine was given to 34 subjects split into three cohorts to evaluate three different doses of the vaccine following 30 days of abstinence. Two subjects in each cohort
received a placebo and the rest received active vaccine. The study's participants had to meet the criteria for cocaine dependence, including a three- to 10-year cocaine habit, and willingness to get treatment and participate in the study.
The people in the study, Kosten said, had a motivation to want to stop using cocaine. This desire to stop is the key factor of any successful treatment outcome.
The vaccine does not take away the desire or the craving for cocaine, Kosten said, but the antibodies it generates block the priming effect and the reinforcement of the craving, if a recovering addict takes cocaine after giving up the drug. To override the vaccine's effects, it may be possible to take massive amounts of cocaine, but it is unlikely that addicts who are actively working to overcome their addiction would want to do that.
Kosten is currently conducting a Phase 11a dose escalation trial involving cocaine addicts in an out-patient treatment program. Once this is complete, a dose will be selected for pivotal efficacy trials, which will aim to evaluate the effect of TA-CD on reducing patient cocaine use.
Cocaine is the second most commonly abused drug after alcohol and the average age of a cocaine user is 42. Most cocaine addicts are treated by physicians or psychiatrists in drug rehabilitation centers. Due to the high relapse rate associated with current therapies, Kosten said, there is a clear need for an effective treatment to be used alongside a behavioral program.
The study was supported by the National Institute on Drug Abuse (NIDA), one of the National Institutes of Health.
TA-CD is being developed by Cantab Pharmaceuticals plc, a Cambridge, England-based biopharmaceutical company.
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