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The Truth About the "New" Coke Vaccine

Scientists are heralding the novel cocaine vaccine as a landmark anti-addiction drug. But how well does it really work?

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A shot in the arm for addiction treatment? ThinkStock

By Walter Armstrong

03/23/11

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Addiction is hell. Addicts can trace its every detail in their sleep, while scientists are left to stumble around in the dark. Margaret Haney, a neurobiologist who heads Columbia University’s substance-abuse research center, has been mapping the particular hell of cocaine addiction for over 15 years. She displays a fitting humility in the face of its mysteries. One of the leading researchers at work on cocaine vaccine development, she frequently fields desperate phone calls from people asking how they can get the treatment for a friend or family member.

They can’t, because none exists. The most advanced candidate, dubbed TA-CD (“therapy for addiction—cocaine addiction”), is still in clinical trials. Its performance in rats is brilliant; in humans, not so much. “People have a mistaken view of how a vaccine might work, thinking of it as magic, where what it’s doing, at best, is blunting the effects,” Haney told the Washington Post in January. “They get very excited, and it’s heartbreaking."

This is the experimental drug about which Time magazine blared, “New Hope for an Anti-Cocaine Vaccine,” in January. Likewise, many media reports accentuated the positive to be found in the latest TA-CD data published in the Archives of General Psychology. It was left to Newsweek to play the skeptic, acidly retorting, “Forget the Coke Vaccine.” The truth, as banal it sounds, lies somewhere between Time and Newsweek’s version of events.
 
The take-home from the study is that 20 percent of the addicts who were treated with the vaccine were able to cut their consumption of cocaine by half or more. That sounds hopeful enough, but the specifics of the study guard against too much optimism. The study was small (115 people) and relatively brief (24 weeks). The vaccine worked in only 11 of 55 cases; it took two months to kick in, and after two more months, its benefits had fizzled out.
 
TA-CD first made headlines way back in the mid-'90s, so progress has been halting. The field of addiction treatment has yielded many buds but little fruit, for several reasons: science, money, and stigma. Vaccines, which tend to be one-time shots rather than daily meds, aren’t major moneymakers for Big Pharma. (One notable exception is nicotine addiction—drug companies are racing to bring a number of competing late-stage version to market.) In addition, the well-being of people hooked on illegal substances isn’t exactly a top priority on the nation’s health agenda. Antabuse and methadone, the most widely used drugs for alcoholism and heroin addiction, respectively, have both been around for more than 50 years. Plus, the infinitely complex workings of the brain remain a riddle to science—and to any addict who, despite the best intentions, relapses on the road to recovery.
 
With its status as the first vaccine against an illegal substance to advance into late-stage clinical trials, TA-CD is a landmark drug. An enormous investment (of dollars, decades, reputations, etc.,) is at stake in its success or failure. Notably, the National Institute on Drug Abuse has backed its development with millions in grants. Equally important, approval of TA-CD would validate the vaccine-for-addiction model, helping some 200 versions for cocaine, heroin, meth, and even alcohol attract backing. So, in the absence of any other medication for cocaine addiction, odds are that TA-CD will manage, with its middling benefits, to make it to market. Finally Haney would have more than a mere promise to offer desperate callers.
 
If TA-DC were magic, as many people believe when they hear the words cocaine vaccine, it would end relapses by blocking the insidious cravings and triggers that can, in a flash, turn a sane, sober ex-addict into his wild-eyed coke-fiend alter ego. But the mechanisms that flip the switch from no to yes in the addict’s brain, apparently stealing every last ounce of impulse control, remain a black box awaiting some future Nobel Prize winner. Current TA-CD researchers like Haney are no slouches, however, and their strategy is to do an end run around the brain-driven sources of relapse by developing a vaccine that simply keeps cocaine from entering the brain in the first place. If you were to slip up, the Bolivian marching powder’s amazing rush and buzz would be blunted, if not blocked entirely, by the vaccine. Without that reward, your cravings and triggers would start to fade, gradually tipping the scales in favor of your sober self over your inner cokehead.
 
TA-CD operates like any other vaccine—you get a shot that exposes you to a harmless amount of the target (whether it’s the flu virus or the cocaine molecule), and your immune system mounts a defense, using antibodies primed to attack that specific intruder. But as fate would have it, the cocaine molecule is exceedingly small, even for a molecule. That’s another reason that it has taken so long to get a cocaine vaccine into human trials. The antibodies can’t find the coke molecules, which your bloodstream ferries from your nose straight into your brain’s reward pathways.
 

The designers of the TA-CD vaccine solved that problem, displaying an unusual amount of scientific jujitsu. They devised a cocaine-molecule look-alike of much greater size and attached it to a deactivated piece of cholera toxin, which enhances the immune response by tricking antibodies into attacking the fake coke targets. (Why cholera? Because the disease is very rare in Western nations, where most cocaine is consumed, so a natural immunity doesn’t already exist.) The coke-like molecule, with antibodies latched onto it, is now too big to pass through the blood-brain barrier.
 
Sponge-like, the vaccine, when successful, not only reduces the amount of blow that hits your brain but also slows it down, muting the feel-good effects. The vax cut the levels of cocaine in rats’ brains by as much as 80%, according to Haney.
 
The study recruited over 100 folks from a methadone program outside New Haven. The majority were crack users; a minority were also addicted to heroin, marijuana, and/or alcohol. Plus, they were taking the clinic’s anti-opioid offering. Add TA-CD to that chemical mix, and teasing out a direct effect of any one drug is a murky matter.
 
A series of five TA-CD shots were administered to half the group over a period of 12 weeks; the other half got dummy jabs. Urine samples were taken three times a week during the 24-week study to measure cocaine use. The results? “In this study, immunization did not achieve complete abstinence from cocaine use,” Thomas Kosten, MD, a substance-abuse expert at Baylor College of Medicine who pioneered work on TA-CD, told the Post. (He’s evidently also an expert at spin.) “Previous research has shown, however, that a reduction in use is associated with a significant improvement in cocaine abusers’ social functioning and thus is therapeutically meaningful.”
 
In fact, “complete abstinence” wasn’t remotely on anyone’s agenda. Only 38 percent of the vaccinated group developed enough antibodies to actually blunt the effects of the cocaine, but they did produce a greater proportion (45%) of cocaine-free pee cups than everybody else (35%). So the vaccine worked in 11 out of 55 cases—which means that clients who cut their cocaine use in half were hailed as proof of the drug's success.
 
But certain negatives were noted in the trials as well. For one, no antibodies at all were produced in one-quarter of the vaccinated folks. The reason for this Haney calls “the million-dollar question.” There were also some amusing crazy-addict anecdotes, showing how the vaccine, even when it works, can backfire. Some volunteers, desperate for a high, were compelled to blow enormous quantities of coke—10 times as much as had ever been recorded in any such study—in an effort to overcome the dulling powers of the vaccine. Not surprisingly, a few poor souls went broke in the bargain, Kosten reported. (Fortunately, no one OD’d or had a heart attack—a compounded risk given that not only cocaine but the vaccine itself can cause a rapid increase in heart rate as well as other serious cardio effects.)
 
Because the drug’s benefits can be thwarted by the use of other stimulants like methamphetamine, its most cost-effective use will be for addicts already committed to recovery. “I believe that this approach will work for motivated patients in that it will buy them a period of time where cocaine's effects are blunted, allowing them to focus on treatment. There are clinical data supporting this idea,” says Haney, whose own study of measuring TA-CD antibodies in crack smokers was published in Biological Psychiatry in 2009.
 
With the National Institute on Drug Abuse’s weighty support, late-stage trials of TA-CD in 300 coke-only addicts are currently enrolling around the country. Results are due in 2014. If these data confirm the 20% efficacy rate, the drug could be available as early as 2016. Iffier than the vax’s success rate is the likelihood of a drug company picking up the tab for its marketing. (Should all these stars align, TA-DC will join the many other, only partially effective behavioral treatments for cocaine addiction. Its trailblazing as the first vaccine against an illegal drug may, in the long run, matter even more.
 
Walter Armstrong is the Deputy Editor of The Fix and the former Editor-in-Chief of Poz Magazine. He also wrote Spiking Opioid Abuse Linked to Changing Prescription Patterns.
 

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