Cocaine Vaccine Passes Key Hurdle
Human Clinical Trials on the Horizon (May 10)
Researchers at Weill Cornell Medical College have successfully tested their novel anti-cocaine vaccine in primates, bringing them closer to launching human clinical trials.
Their study, published online by the journal Neuropsychopharmacology, used a radiological technique to demonstrate that the anti-cocaine vaccine prevented the drug from reaching the brain and producing a dopamine-induced high.
"The vaccine eats up the cocaine in the blood like a little Pac-man before it can reach the brain," says the study's lead investigator, Dr. Ronald G. Crystal, chairman of the Department of Genetic Medicine at Weill Cornell Medical College.
"We believe this strategy is a win-win for those individuals, among the estimated 1.4 million cocaine users in the United States, who are committed to breaking their addiction to the drug," he says. "Even if a person who receives the anti-cocaine vaccine falls off the wagon, cocaine will have no effect." Dr. Crystal says he expects to begin human testing of the anti-cocaine vaccine within a year.
Cocaine, a tiny molecule drug, works to produce feelings of pleasure because it blocks the recycling of dopamine -- the so-called "pleasure" neurotransmitter -- in two areas of the brain, the putamen in the forebrain and the caudate nucleus in the brain's center. When dopamine accumulates at the nerve endings, "you get this massive flooding of dopamine and that is the feel good part of the cocaine high," says Dr. Crystal.
The novel vaccine Dr. Crystal and his colleagues developed combines bits of the common cold virus with a particle that mimics the structure of cocaine. When the vaccine is injected into an animal, its body "sees" the cold virus and mounts an immune response against both the virus and the cocaine impersonator that is hooked to it. "The immune system learns to see cocaine as an intruder," says Dr. Crystal. "Once immune cells are educated to regard cocaine as the enemy, it produces antibodies, from that moment on, against cocaine the moment the drug enters the body."
In their first study in animals, the researchers injected billions of their viral concoction into laboratory mice, and found a strong immune response was generated against the vaccine. Also, when the scientists extracted the antibodies produced by the mice and put them in test tubes, it gobbled up cocaine. They also saw that mice that received both the vaccine and cocaine were much less hyperactive than untreated mice given cocaine.
The study was funded by grants from the National Institute on Drug Abuse (NIDA.