Margaret Haney, Ph.D. Associate Professor of Clinical Neuroscience Columbia University

1. Immunotherapies for the Treatment of Drug Dependence Margaret Haney, Ph.D. Associate Professor of Clinical Neuroscience Columbia University New York State Psychiatric Institute Supported by National Institute of Drug Abuse

2. Outline • Drug Abuse • Immunological strategies • Latest clinical findings: Cocaine and nicotine

3. Drug Dependence: Major public health problem • Human costs (lives damaged by addiction) and financial costs ($67 billion/year in health care, crime, lost job productivity, etc.) • 46 million adult cigarette smokers in U.S.: 70% want to quit but < 5% succeed • 1.7 million dependent on cocaine in U.S.: 53% seeking treatment

4. Chronic Relapsing Disorder • Addiction: Compulsive behavior, characterized by a loss of control in limiting drug intake • Drug users often enter treatment with strong intentions, but a variety of factors (drug cues, drug exposure, stress) often make it difficult to maintain abstinence for long periods • Never expect to ‘cure’ drug dependence. Goal is to decrease likelihood of relapse and increase length of abstinence

5. Pharmacotherapy • Cigarettes: Nicotine replacement, bupropion • Heroin: Methadone, naltrexone, buprenorphine • Alcohol: Naltrexone, acamprosate, disulfiram • Cocaine: -- • Methamphetamine: --

6. Medications act at CNS • Mimic drug of abuseMethadone,Nicotine patch • Block drug of abuse Naltrexone • Decrease‘craving’ or withdrawalBupropion

7. Drugs of abuse are small molecules that rapidly cross the blood-brain barrier, and bind at sites mediating reward, cognition, emotion, memory Treatment medications often target the same CNS pathways, and therefore can affect normal function as well (side effects) Even effective medications do not work for many people More treatment options are needed

8. Novel Approach: Target Drug rather than Brain Immunotherapy blocks the effects of abused drugs peripherally, before they reach the brain No CNS side effects

9. Unlike bacteria or viruses, drugs of abuse alone do not elicit an immune response • To generate anti-drug antibodies, a derivative of the drug is irreversibly bound to an antigenic protein carrier • Drugs bound to antibody cannot cross the blood-brain barrier

10. Antibodies typically have high affinity and high specificity (not binding to drug metabolites or other drugs or medications) • Mechanism of action: do not block drug effects completely (unlike vaccines for infectious disease), but act by slowing the rate in which abused drugs get into brain • For all drugs of abuse: faster onset of effect, greater abuse liability, so slowing rate of entry decreases drug reinforcment

11. Smoked cocaine produces comparable effects as IV cocaine

12. Blood/Brain Barrier Blood/Brain Barrier Pre-vaccine Post-vaccine Drug in Circulation Drug in Circulation

13. Plasma concentrations of drug are higher following vaccination, but drug bound to antibody, so not toxic • In rats, cocaine-specific antibodies reduced early cocaine distribution to brain and heart by 25-80%(Kantak et al., 2000) • Antibody response fades over time, so boosters needed to maintain serumantibody levels

14. Immunological Approaches • Passive Immunization: Administer monoclonal antibodies generated in vitro • Active Immunization:Vaccinate to generate antibodies • Catalytic Antibodies: Enhance drug metabolism

15. Passive Immunization Pros: Precisely controlled dosing Immediate protection Cons: High doses needed Cost Drugs tested to date: Cocaine, nicotine, PCP

16. Active Immunization Pros: Easy, relatively inexpensive Antibodies long-lasting (e.g., 3-6 months), a particular benefit in treating drug addiction Presence of abused drug does not interfere with immunological response, so vaccinations can occur while drug use is ongoing

17. Active Immunization (cont’d) Cons: Takes time for antibodies to be generated (repeated vaccinations over about 2 months) Enormous individual variability in amount of antibody generated Surmountable Substitution Drugs tested to date: Cocaine, nicotine, methamphetamine

18. Catalytic Antibodies Pros: Not easily surmounted Cons: Limited to drugs metabolized by simple hydrolysis (e.g., cocaine) Effects short-lived Large quantities of antibody needed Drugs tested to date: Cocaine

19. COCAINE

20. Xenova Research Ltd: TA-CD • b subunit of recombinant cholera toxin: Highly immunogenic protein eliciting potent antibody response • Covalently linked to succinyl norcocaine • Aluminum hydroxide adjuvant

21. Cocaine self-administration

22. Cocaine Self-Administration in rats(Fox et al., 1996) Passive Immunization 10 Cocaine 8 6 Infusions per hour Saline 4 Cocaine + Antibody 2 0 baseline 1 2 3 4 5 Day

23. Degree to which cocaine self-administration is decreased depends on plasma antibody concentration • There is a threshold concentration of plasma antibody needed to block cocaine self-administration

24. Relapse • In humans, relapse to drug use can be triggered by low doses of abused druge.g., one drink for an abstinent alcoholic may trigger a return to pre-abstinent levels of drinking • In animal models, low doses of cocaine trigger a return to cocaine-seeking • Vaccinated rats did not show this response(Kantak et al., 2000) • Suggests vaccine may help prevent relapse

25. Clinical Data: TA-CD • Phase II trial conducted at Yale School of Medicine • Cocaine-dependent outpatients (n=21): TA-CD (82, 360 mg) administered 3-5 times over 12 wks Data from Xenova website, Kosten et al., 2002

26. Clinical Data: TA-CD (cont’d) • Large variability in plasma antibody levels, but efficacy dose-dependent: Individuals receiving more frequent vaccinations at higher doses of TA-CD had higher antibody levels and showed fewer cocaine+ urines • Peak antibody levels: 3 monthsLevels persist up to 6 months • Boosters (n=8): antibody response in 2-4 wks • Ongoing large Phase II trial in methadone-maintained cocaine-dependent patients

27. Preclinical Human Laboratory Study • Determine direct relationship between plasma antibody levels, and cocaine’s subjective and cardiovascular effects • Cocaine-dependent volunteers not seeking treatment for cocaine use • Vaccinations: weeks 1, 3, 5, 9 • Inpatient 2 nights/wk for 13 weeks 3 cocaine sessions/week, each testing one dose of smoked cocaine (0, 25, 50 mg)

28. Cocaine Sessions MinuteEvent -30 Baseline Cardiovascular and Mood Scales -8 Baseline Plasma Cocaine and Antibody Measures 0 First Cocaine Administraton 4 Mood Scales Plasma Measures 15 Mood Scales 20 Second Cocaine Administration 24 Mood Scales Plasma Measures 35 Mood Scales Plasma Measures 50 Mood Scales Plasma Measures

29. Preliminary Data • Data collection ongoing: 82 mg TA-CD (n=4)360 mg TA-CD (n=4) • Well tolerated; side effects minor and infrequent • *No evidence of attempts to surmount. Participants report that if they do not feel cocaine’s effects they stop using

30. Plasma Antibody (n=7) 1400 82 ug 360 ug 1200 1000 800 Titer 600 400 200 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Weeks

31. Laboratory study: PET • PET imaging to determine brain cocaine concentrations and dopamine transporter occupancy (DAT) before and after vaccination • Determine whether vaccine effectively reduces the transport of cocaine into brain, and reduces blockade of DAT by cocaine • Data not yet analyzed

32. NICOTINE

33. Nicotine may be especially promising as a target drug for immunotherapy since lower daily doses of nicotine are consumed (milligrams as opposed to grams of cocaine) • Presumably, lower serum antibody levels needed to decrease nicotine’s effects

34. Animal Models: Vaccination • nicotine distribution to the rat brain by 40-60% • nicotine self-administration • nicotine-induced drug seeking • blocks nicotine alleviation of withdrawal **may block relapse related to relief of withdrawal

35. Nicotine replacement • Vaccination most effective at blocking earlydistribution of nicotine to brain • Not as effective blocking slow, continuous infusions as with nicotine patch • May be possible to combine nicotine patch and nicotine vaccine therapy

36. Clinical Data: NicVAX • Nabi Biopharmaceuticals: Phase II trial (n=68) • Doses: 0, 50, 100, 200 mgVaccinate: Day 0, 28, 56 and 182 • Well-toleratedStopped smoking placebo: 9%200 mg: 33% Data from Nabi website

37. Additional Clinical Data • Xenova Group (TA-NIC) Nicotine butyric acid covalently linked to recombinant cholera toxin B. Phase I testing (n=60) • Cytos Biotechnology (CYT002-NicQb):Phase II study (n=300) Data from company websites

38. METHAMPHETAMINE • Active Immunization: Vaccine produced antibodies but did not alter locomotor activity • Passive Immunization: Decreased drug distribution by > 60% but not w/i first 15 min of administration (not rapid binding). No robust decrease in locomotor or reinforcing effects • Issue: Methamphetamine metabolized to pharmacologically active metabolites not bound by antibody • Conclusion: Methamphetamine immunotherapy shows promise, but higher affinity antibodies and a combination of different antibodies may be needed

39. Overall Conclusions • Current results encouraging: few side effects, reliable antibody production, and safe in combination with drug of abuse • Never expect to ‘cure’ drug dependence. Goal is to improve treatment options • Need a variety of approaches: Immuno-therapy may be one tool, along with behavioral and pharmacologic treatment, to facilitate abstinence

40. Chronic Relapsing Disorder • If vaccinated patient relapses, a portion of dose will bind the antibody and not enter the brain • Patient may feel a muted drug effect, and opt not to waste money on more drug • Treatment approaches requiring minimal compliance by patient ideal • Impact of immunotherapy may be most profound for drugs with no effective pharmacotherapy (cocaine, methamphetamine, PCP)

41. Binding Capacity Surprising result is that immunotherapies appear effective even when amount of drug substantially exceeds calculated binding capacity of antibodiesex: nicotine vaccine reduced drug distribution to brain even when single nicotine doses exceeded estimated binding capacity by 67-fold

42. Binding Capacity • Immunization appears to preferentially decrease drug distribution to the brain compared to other tissues • Vaccination sequesters nicotine both in the serum and in fat or lung tissue, depending on dosing regimen • Tissue-specific effects may explain how vaccination reduces drug distribution to brain at doses that exceed binding capacity

43. Issues • Time to build antibody titers (approx 8 wks) *Start vaccinating while drug use ongoing or during stay in inpatient treatment facility*Combine passive and active immunization? • Individual variability in antibody production * Vaccine won’t be effective for everybody • Antibody response fades * Need boosters approx 4 month intervals

44. Issues (cont’d) • Substitution * Realistic to presume some will switch to alternate drugs of abuse, yet shouldn’t discourage pursuit of effective therapy • Involuntary vaccination or vaccination of minors? * Given surmountability, not advised; need active participation of individual receiving immunotherapy for it to work safely

45. Summary • Stimulant and tobacco dependence are global problems • Immunotherapy is a novel approach with potential for wide application • Immunotherapy will not guarantee drug abstinence, but could increase the odds a motivated treatment seeker would not relapse to pre-vaccine levels of drug use

46. Acknowledgements Richard Foltin, Ph.D. NIDA Diana Martinez, M.D. Xenova Research Ltd. Recent Reviews 1. Haney and Kosten (2004) Expert Review Vaccines 3: 11-18 2. Pentel (2004) New Treatments for Addiction National Academy of Sciences