Cocaine vaccine for the treatment of cocaine dependence in methadone-maintained patients: a randomized, double-blind, placebo-controlled efficacy trial

Pharmacokinetic strategies for treatment of drug overdose and addiction

The pharmacokinetic treatment strategy targets the drug molecule itself, aiming to reduce drug concentration at the site of action, thereby minimizing any pharmacodynamic effect. This approach might be useful in the treatment of acute drug toxicity/overdose and in the long-term treatment of addiction. Phase IIa controlled clinical trials with anticocaine and antinicotine vaccines have shown good tolerability and some efficacy, but Phase IIb and III trials have been disappointing because of the failure to generate adequate antibody titers in most participants. Monoclonal antibodies against cocaine, methamphetamine and phencyclidine have shown promise in animal studies, as has enhancing cocaine metabolism with genetic variants of human butyrylcholinesterase, with a bacterial esterase, and with catalytic monoclonal antibodies. Pharmacokinetic treatments offer potential advantages in terms of patient adherence, absence of medication interactions and benefit for patients who cannot take standard medications.

An oxycodone conjugate vaccine elicits drug-specific antibodies that reduce oxycodone distribution to brain and hot-plate analgesia

Opioid conjugate vaccines have shown promise in attenuating the behavioral effects of heroin or morphine in animals. The goal of this study was to extend this approach to oxycodone (OXY), a commonly abused prescription opioid. Haptens were generated by adding tetraglycine (Gly)(4) or hemisuccinate (HS) linkers at the 6-position of OXY. Immunization of rats with OXY(Gly)(4) conjugated to the carrier proteins bovine serum albumin (BSA) or keyhole limpet hemocyanin (KLH) produced high-titer antibodies to OXY and its metabolite oxymorphone with substantially lower affinities for other structurally related opioid agonists and antagonists. There was no measurable binding of antibody by the (Gly)(4) linker alone or off-target opioids methadone and buprenorphine. OXY(HS) conjugates were less immunogenic despite achieving protein haptenation ratios comparable to OXY(Gly)(4)-BSA. In rats given a single intravenous dose of OXY, immunization with OXY(Gly)(4)-KLH increased OXY protein binding and retention in serum while decreasing its unbound (free) concentration in plasma and distribution to brain. Vaccine efficacy correlated with serum antibody titers, and it was greatest in rats given the lowest OXY dose (0.05 mg/kg) but was significant even after a larger OXY dose (0.5 mg/kg), equivalent to the high end of the therapeutic range in humans. These effects of OXY(Gly)(4)-KLH on drug disposition were comparable to those of nicotine or cocaine vaccines that are in clinical trials as addiction treatments. Immunization with OXY(Gly)(4)-KLH also reduced OXY analgesia in a thermal nociception test. These data support further study of vaccination with the OXY(Gly)(4)-KLH immunogen as a potential treatment option for OXY abuse or addiction.

Drug policy and the public good: evidence for effective interventions

Debates about which policy initiatives can prevent or reduce the damage that illicit drugs cause to the public good are rarely informed by scientific evidence. Fortunately, evidence-based interventions are increasingly being identified that are capable of making drugs less available, reducing violence in drug markets, lessening misuse of legal pharmaceuticals, preventing drug use initiation in young people, and reducing drug use and its consequences in established drug users. We review relevant evidence and outline the likely effects of fuller implementation of existing interventions. The reasoning behind the final decisions for action might be of a non-scientific nature, focused more on what the public and policy-makers deem of value. Nevertheless, important opportunities exist for science to inform these deliberations and guide the selection of policies that maximise the public good.

Vaccines against drug abuse

The currently available medications for the treatment of drug abuse have had only limited success. Anti-addiction vaccines, aimed at eliciting antibodies that block the pharmacological effects of drugs, have great potential for treating drug abuse. We review the status of two vaccines that are undergoing clinical trials (for cocaine and nicotine addiction) and two that are still in preclinical development (for methamphetamine and heroin addiction). We also outline the challenges and ethical concerns associated with the development of anti-addiction vaccines and their use as future therapeutics.

Vaccines targeting drugs of abuse: is the glass half-empty or half-full?

The advent of vaccines targeting drugs of abuse heralded a fundamentally different approach to treating substance-related disorders. In contrast to traditional pharmacotherapies for drug abuse, vaccines act by sequestering circulating drugs and terminating the drug-induced 'high' without inducing unwanted neuromodulatory effects. Drug-targeting vaccines have entered clinical evaluation, and although these vaccines show promise from a biomedical viewpoint, the ethical and socioeconomic implications of vaccinating patients against drugs of abuse merit discussion within the scientific community.

Immunotherapy for drug abuse

Substance use disorders continue to be major medical and social problems worldwide. Current medications for substance use disorders have many limitations such as cost, availability, medication compliance, dependence, diversion of some to illicit use and relapse to addiction after discontinuing their use. Immunotherapies using either passive monoclonal antibodies or active vaccines have distinctly different mechanisms and therapeutic utility from small molecule approaches to treatment. They have great potential to help the patient achieve and sustain abstinence and have fewer of the above limitations. This review covers the cocaine vaccine development in detail and provides an overview of directions for developing anti-addiction vaccines against the abuse of other substances. The notable success of the first placebo-controlled clinical trial of a cocaine vaccine, TA-CD, has led to an ongoing multi-site, Phase IIb clinical trial in 300 subjects. The results from these trials are encouarging further development of the cocaine vacine as one of the first anti-addiction vaccines to go forward to the U.S. Food and Drug Administration for review and approval for human use.

Vaccines in the Treatment of Substance Abuse

Reconceptualizing drugs as toxins allowed an important shift in the approach to the treatment of substance abuse, because it ushered in consideration of immunological methods of pharmacotherapy. This paradigm shift represented a dramatic departure from previously considered approaches to pharmacotherapy for substance use disorders (SUDs), which had up until that time focused predominantly on either agonist and/or antagonist medications meant to block drug effects or to decrease reward, reinforcement, or craving. Use of immunological theory in SUD treatment also meant that 1) a potentially addicting medication would not be administered as part of therapy and 2) side effects could be limited, because the individual's immune system would be responsible for delivering treatment.

Structurally distinct nicotine immunogens elicit antibodies with non-overlapping specificities

Nicotine conjugate vaccine efficacy is limited by the concentration of nicotine-specific antibodies that can be reliably generated in serum. Previous studies suggest that the concurrent use of 2 structurally distinct nicotine immunogens in rats can generate additive antibody responses by stimulating distinct B cell populations. In the current study we investigated whether it is possible to identify a third immunologically distinct nicotine immunogen. The new 1'-SNic immunogen (2S)-N,N'-(disulfanediyldiethane-2,1-diyl)bis[4-(2-pyridin-3-ylpyrrolidin-1-yl)butanamide] conjugated to keyhole limpet hemocyanin (KLH) differed from the existing immunogens 3'-AmNic-rEPA and 6-CMUNic-BSA in linker position, linker composition, conjugation chemistry, and carrier protein. Vaccination of rats with 1'-SNic-KLH elicited high concentrations of high affinity nicotine-specific antibodies. The antibodies produced in response to 1'-SNic-KLH did not appreciably cross-react in ELISA with either 3'-AmNic-rEPA or 6-CMUNic-BSA or vice versa, showing that the B cell populations activated by each of these nicotine immunogens were non-overlapping and distinct. Nicotine retention in serum was increased and nicotine distribution to brain substantially reduced in rats vaccinated with 1'-SNic-KLH compared to controls. Effects of 1'-SNic-KLH on nicotine distribution were comparable to those of 3'-AmNic-rEPA which has progressed to late stage clinical trials as an adjunct to smoking cessation. These data show that it is possible to design multiple immunogens from a small molecule such as nicotine which elicit independent immune responses. This approach could be applicable to other addiction vaccines or small molecule targets as well.

Broad neutralization coverage of HIV by multiple highly potent antibodies

Broadly neutralizing antibodies (bnAbs) against highly variable viral pathogens are much sought-after to treat or protect against global circulating viruses. We have probed the neutralizing antibody repertoires of four HIV-infected donors with remarkably broad and potent neutralizing responses and rescued 17 new monoclonal antibodies (MAbs) that neutralize broadly across clades. Many of the new MAbs are almost 10-fold more potent than the recently described PG9, PG16, and VRC01 bnMAbs and 100-fold more potent than the original prototype HIV bnMAbs^1–3. The MAbs largely recapitulate the neutralization breadth found in the corresponding donor serum and many recognize novel epitopes on envelope (Env) glycoprotein gp120, illuminating new targets for vaccine design. Analysis of neutralization by the full complement of anti-HIV bnMAbs now available reveals that certain combinations of antibodies provide significantly more favorable coverage of the enormous diversity of global circulating viruses than others and these combinations might be sought in active or passive immunization regimes. Overall, the isolation of multiple HIV bnMAbs, from several donors, that, in aggregate, provide broad coverage at low concentrations is a highly positive indicator for the eventual design of an effective antibody-based HIV vaccine.

Novel pharmacotherapeutic treatments for cocaine addiction

Cocaine is a stimulant that leads to the rapid accumulation of catecholamines and serotonin in the brain due to prevention of their re-uptake into the neuron that released the neurotransmitter. Cocaine dependence is a public health concern and cause of significant morbidity and mortality worldwide. At present, there are no approved medications for the treatment of this devastating illness, and behavioral interventions have proven to be of limited use. However, there have been a number of recent trials testing promising agents including dopamine agonists, GABAergic medications and the cocaine vaccine. Here we discuss the most recent human clinical trials of potential medications for treatment of cocaine dependence, as well as pre-clinical studies for another promising agent, levo tetrahydropalmatine. Examination of these recent findings shows promise for GABAergic medications and the cocaine vaccine, as well as unique medications such as disulfiram, whose mechanism remains to be determined. Future work may also confirm specific subgroups of patients for treatment response based on clinical characteristics, biomarkers and pharmacogenetics. This review highlights the need for further, bigger studies in order to determine optimal clinical usage.

A morphine/heroin vaccine with new hapten design attenuates behavioral effects in rats

Heroin use has seriously threatened public heath in many countries, but the existing therapies continue to have many limitations. Recently, immunotherapy has shown efficacy in some clinical studies, including vaccines against nicotine and cocaine, but no opioid vaccines have been introduced in clinical studies. The development of a novel opioid antigen designed specifically for the prevention of heroin addiction is necessary. A morphine-keyhole limpet hemocyanin conjugate was prepared and administered subcutaneously in rats. Antibody titers in plasma were measured using an enzyme-linked immunosorbent assay (ELISA). Competitive ELISA was used to assess the selectivity of the antibodies. Dopamine concentrations in the nucleus accumbens in rats after vaccine administration were determined by high-performance liquid chromatography with electrochemical detection. The effects of the vaccine on the heroin-primed restatement of self-administration and locomotor sensitization were evaluated. A novel hapten, 6-glutarylmorphine, was produced, and the vaccine generated a high antibody titer response. This vaccine displayed specificity for both morphine and heroin, but the anti-morphine antibodies could not recognize dissimilar therapeutic opioid compounds, such as buprenorphine, methadone, naloxone, naltrexone, codeine, and nalorphine. The morphine antibody significantly decreased morphine-induced locomotor activity in rats after immunization. Importantly, rats immunized with this vaccine did not exhibit heroin-primed reinstatement of heroin seeking when antibody levels were sufficiently high. The vaccine reduced dopamine levels in the nucleus accumbens after morphine administration, which is consistent with its behavioral effects. These results suggest that immunization with a novel vaccine is an effective means of inducing a morphine-specific antibody response that is able to attenuate the behavioral and psychoactive effects of heroin.

Anti-addiction vaccines

Despite intensive efforts to eradicate it, addiction to both legal and illicit drugs continues to be a major worldwide medical and social problem. Anti-addiction vaccines can produce the antibodies to block the effects of these drugs on the brain, and have great potential to ameliorate the morbidity and mortality associated with illicit drug intoxications. This review provides a current overview of anti-addiction vaccines that are under clinical trial and pre-clinical research evaluation. It also outlines the development challenges, ethical concerns, and likely future intervention for anti-addiction vaccines.

Aripiprazole maintenance increases smoked cocaine self-administration in humans

RATIONALE

Partial dopamine receptor agonists have been proposed as candidate pharmacotherapies for cocaine dependence.

OBJECTIVE

This 42-day, within-subject, human laboratory study assessed how maintenance on aripiprazole, a partial D(2) receptor agonist, influenced smoked cocaine self-administration, cardiovascular measures, subjective effects, and cocaine craving in nontreatment-seeking, cocaine-dependent volunteers.

METHODS

In order to achieve steady-state concentrations, participants (n = 8 men) were administered placebo and aripiprazole (15 mg/day) capsules in counter-balanced order for 21 days. A smoked cocaine dose-response curve (0, 12, 25, 50 mg) was determined twice under placebo and aripiprazole maintenance. Sessions comprised a "sample" trial, when participants smoked the cocaine dose available that session, and five choice trials, when they responded on a progressive-ratio schedule of reinforcement to receive the cocaine dose or receive $5.00.

RESULTS

Cocaine's reinforcing, subjective, and cardiovascular effects were dose-dependent. Aripiprazole significantly increased cocaine (12, 25 mg) self-administration. Following a single administration of cocaine (25 mg), aripiprazole decreased ratings of how much participants would pay for that dose. Following repeated cocaine (50 mg) self-administration, aripiprazole decreased ratings of cocaine quality, craving, and good drug effect as compared to placebo.

CONCLUSIONS

These data suggest that aripiprazole may have increased self-administration to compensate for a blunted subjective cocaine effect. Overall, the findings do not suggest aripiprazole would be useful for treating cocaine dependence.

Combined active and passive immunization against nicotine: minimizing monoclonal antibody requirements using a target antibody concentration strategy

Nicotine vaccines have shown preliminary evidence of efficacy for enhancing smoking cessation rates, but the serum nicotine-specific antibody (NicAb) concentrations produced are highly variable and many subjects do not develop effective levels. As an alternative to vaccination, passive immunization with nicotine-specific monoclonal antibodies could produce more uniform serum NicAb concentrations, but its use is limited by their high cost and shorter elimination half-life. This study investigated supplementing vaccination with monoclonal antibodies in a targeted fashion to increase vaccine efficacy while minimizing the required monoclonal antibody dose. Rats were vaccinated and then given individualized supplemental doses of the nicotine-specific monoclonal antibody Nic311 to achieve a target total serum NicAb concentration known to be effective for blocking locomotor sensitization (LMS) to nicotine. Rats received vaccine, Nic311, both, or neither, followed by 0.3 mg/kg nicotine s.c. for 10 days to produce LMS. Combination immunotherapy completely blocked the development of LMS, while monotherapy with vaccine or Nic311 alone was only minimally effective. Lower brain nicotine levels were associated with reduced locomotor activity averaged over days 7-10. Despite its greater efficacy, combination immunotherapy did not reduce the variability in the resulting total serum NicAb concentrations. Variability in total serum NicAb concentrations was contributed to by both vaccine-generated antibody and by Nic311. These data show that combination immunotherapy, using a Nic311 dose that is by itself only minimally effective, can substantially enhance nicotine vaccine efficacy. However, variability in serum NicAb levels with combination immunotherapy may make translation of this approach challenging.

Synthesis of mercapto-(+)-methamphetamine haptens and their use for obtaining improved epitope density on (+)-methamphetamine conjugate vaccines

This study reports the synthesis of the mercapto-hapten (S)-N-(2-(mercaptoethyl)-6-(3-(2-(methylamino)propyl)phenoxy)hexanamide [3, (+)-METH HSMO9] and its use to prepare METH-conjugated vaccines (MCV) from maleimide-activated proteins. MALDI-TOF mass spectrometry analysis of the MCV synthesized using 3 showed there was a high and controllable epitope density on two different carrier proteins. In addition, the MCV produced a substantially greater immunological response in mice than previous METH haptens, and a monoclonal antibody generated from this MCV in mice showed a very high affinity for (+)-METH (K(D) = 6.8 nM). The efficient covalent coupling of (+)-METH HSMO9 to the activated carrier proteins suggests that this approach could be cost-effective for large-scale production of MCV. In addition, the general methods described for the synthesis of (+)-METH HSMO9 (3) and its use to synthesize MCV will be applicable for conjugated vaccines of small molecules and other substances of abuse such as morphine, nicotine, and cocaine.

Differentiating the rapid actions of cocaine

The subjective effects of intravenous cocaine are felt almost immediately, and this immediacy plays an important part in the drug's rewarding impact. The primary rewarding effect of cocaine involves blockade of dopamine reuptake; however, the onset of this action is too late to account for the drug's initial effects. Recent studies suggest that cocaine-predictive cues--including peripheral interoceptive cues generated by cocaine itself--come to cause more direct and earlier reward signalling by activating excitatory inputs to the dopamine system. The conditioned activation of the dopamine system by cocaine-predictive cues offers a new target for potential addiction therapies.

Ethical and policy issues in using vaccines to treat and prevent cocaine and nicotine dependence

PURPOSE OF REVIEW

To describe the rationale of vaccines against cocaine and nicotine, to review progress in developing and trialing vaccines to treat dependence on these drugs and to discuss some of the ethical issues that may arise from their use in legally coerced addiction treatment or for prevention of addiction in adolescents.

RECENT FINDINGS

Several randomized controlled trials of cocaine and nicotine vaccines for relapse prevention have produced mixed results. The studies demonstrate that it is possible to raise antibodies to cocaine and nicotine in humans. In abstinent patients who show high levels of drug antibodies, the rewarding effects of these drugs are attenuated. Phase 2 trials have not found nicotine vaccines to be superior to placebo because only a third of those vaccinated develop sufficient levels of antibody to block the effects of nicotine.

SUMMARY

Vaccines are a novel approach to relapse prevention that need to more reliably induce immunity in a larger proportion of vaccinated patients if they are to protect against relapse after achieving abstinence. Vaccines are unlikely to prevent addiction in adolescents. Their use under legal coercion should only be considered after considerable experience with their use in voluntary patients.

Impact of distinct chemical structures for the development of a methamphetamine vaccine

(+)-Methamphetamine (METH) use and addiction has grown at alarming rates over the past two decades, while no approved pharmacotherapy exists for its treatment. Immunopharmacotherapy has the potential to offer relief through producing highly specific antibodies that prevent drug penetration across the blood-brain barrier thus decreasing reinforcement of the behavior. Current immunotherapy efforts against methamphetamine have focused on a single hapten structure, namely linker attachment at the aromatic ring of the METH molecule. Hapten design is largely responsible for immune recognition, as it affects presentation of the target antigen and thus the quality of the response. In the current paper we report the systematic generation of a series of haptens designed to target the most stable conformations of methamphetamine as determined by molecular modeling. On the basis of our previous studies with nicotine, we show that introduction of strategic molecular constraint is able to maximize immune recognition of the target structure as evidenced by higher antibody affinity. Vaccination of GIX(+) mice with six unique METH immunoconjugates resulted in high antibody titers for three particularly promising formulations (45-108 μg/mL, after the second immunization) and high affinity (82, 130, and 169 nM for MH2, MH6, and MH7 hapten-based vaccines, respectively). These findings represent a unique approach to the design of new vaccines against methamphetamine abuse.

Oral vaccines for preventing cholera

EDITORIAL NOTE

This review is superseded by the published Cochrane Review, Saif‐Ur‐Rahman 2024 [https://doi.org/10.1002/14651858.CD014573], which considers only the oral killed vaccines because the live oral vaccines do not have World Health Organization (WHO) prequalification. Saif‐Ur‐Rahman 2024 also considered only currently available WHO pre‐qualified oral killed cholera vaccines (Dukoral, Shanchol, and Euvichol/Euvichol‐Plus).

BACKGROUND

Cholera is a cause of acute watery diarrhoea which can cause dehydration and death if not adequately treated. It usually occurs in epidemics, and is associated with poverty and poor sanitation. Effective, cheap, and easy to administer vaccines could help prevent epidemics.

OBJECTIVES

To assess the effectiveness and safety of oral cholera vaccines in preventing cases of cholera and deaths from cholera.

SEARCH STRATEGY

In October 2010, we searched the Cochrane Infectious Disease Group Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; EMBASE; LILACS; the metaRegister of Controlled Trials (mRCT), and the WHO International Clinical Trials Registry Platform (ICTRP) for relevant published and ongoing trials.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials of oral cholera vaccines in healthy adults and children.

DATA COLLECTION AND ANALYSIS

Each trial was assessed for eligibility and risk of bias by two authors working independently. Data was extracted by two independent reviewers and analysed using the Review Manager 5 software. Outcomes are reported as vaccine protective efficacy (VE) with 95% confidence intervals (CIs).

MAIN RESULTS

Seven large efficacy trials, four small artificial challenge studies, and twenty-nine safety trials contributed data to this review.Five variations of a killed whole cell vaccine have been evaluated in large scale efficacy trials (four trials, 249935 participants). The overall vaccine efficacy during the first year was 52% (95% CI 35% to 65%), and during the second year was 62% (95% CI 51% to 62%). Protective efficacy was lower in children aged less than 5 years; 38% (95% CI 20% to 53%) compared to older children and adults; 66% (95% CI 57% to 73%).One trial of a killed whole cell vaccine amongst military recruits demonstrated 86% protective efficacy (95% CI 37% to 97%) in a small epidemic occurring within 4 weeks of the 2-dose schedule (one trial, 1426 participants). Efficacy data is not available beyond two years for the currently available vaccine formulations, but based on data from older trials is unlikely to last beyond three years.The safety data available on killed whole cell vaccines have not demonstrated any clinically significant increase in adverse events compared to placebo.Only one live attenuated vaccine has reached Phase III clinical evaluation and was not effective (one trial, 67508 participants). Two new candidate live attenuated vaccines have demonstrated clinical effectiveness in small artificial challenge studies, but are still in development.

AUTHORS' CONCLUSIONS

The currently available oral killed whole cell vaccines can prevent 50 to 60% of cholera episodes during the first two years after the primary vaccination schedule. The impact and cost-effectiveness of adopting oral cholera vaccines into the routine vaccination schedule of endemic countries will depend on the prevalence of cholera, the frequency of epidemics, and access to basic services providing rapid rehydration therapy.

Immunopharmacotherapeutic manifolds and modulation of cocaine overdose

Cocaine achieves its psychostimulant, reinforcing properties through selectively blocking dopamine transporters, and this neurobiological mechanism impedes the use of classical receptor-antagonist pharmacotherapies to outcompete cocaine at CNS sites. Passive immunization with monoclonal antibodies (mAb) specific for cocaine circumvents this problem as drug is sequestered in the periphery prior to entry into the brain. To optimize an immunopharmacotherapeutic strategy for reversing severe cocaine toxicity, the therapeutic properties of mAb GNC92H2 IgG were compared to those of its engineered formats in a mouse overdose model. Whereas the extended half-life of an IgG justifies its application to the prophylactic treatment of addiction, the rapid, thorough biodistribution of mAb-based fragments, including F(ab')₂, Fab and scFv, may correlate to accelerated scavenging of cocaine and reversal of toxicity. To test this hypothesis, mice were administered the anti-cocaine IgG (180 mg/kg, i.v.) or GNC92H2-based agent after receiving an LD₅₀ cocaine dose (93 mg/kg, i.p.), and the timeline of overdose symptoms was recorded. All formats lowered the rate of lethality despite the >100-fold molar excess of drug to antibody binding capacity. However, only F(ab')₂-92H2 and Fab-92 H2 significantly attenuated the progression of premorbid behaviors, and Fab-92H2 prevented seizure generation in a percentage of mice. The calculation of serum half-life of each format demonstrated that the pharmacokinetic profile of Fab-92H2 (elimination half-life, t½~100 min) best approximated that of cocaine. These results not only confirm the importance of highly specific and tight drug binding by the mAb, but also highlight the benefit of aligning the pharmacokinetic and pharmacodynamic properties of the immunopharmacotherapeutic with the targeted drug.

Neuroscience of behavioral and pharmacological treatments for addictions

Although substantial advances have been made in behavioral and pharmacological treatments for addictions, moving treatment development to the next stage may require novel ways of approaching addictions, particularly ways based on new findings regarding the neurobiological underpinnings of addictions that also assimilate and incorporate relevant information from earlier approaches. In this review, we first briefly review theoretical and biological models of addiction and then describe existing behavioral and pharmacologic therapies for the addictions within this framework. We then propose new directions for treatment development and targets that are informed by recent evidence regarding the heterogeneity of addictions and the neurobiological contributions to these disorders.

Translational research in addiction: toward a framework for the development of novel therapeutics

The development of novel substance use disorder (SUD) therapeutics is insufficient to meet the medical needs of a growing SUD patient population. The identification of translatable SUD models and tests is a crucial step in establishing a framework for SUD therapeutic development programs. The present review begins by identifying the clinical features of SUDs and highlights the narrow regulatory end-point required for approval of a novel SUD therapeutic. A conceptual overview of dependence is provided, followed by identification of potential intervention targets in the addiction cycle. The main components of the addiction cycle provide the framework for a discussion of preclinical models and their clinical analogs, all of which are focused on isolated behavioral end-points thought to be relevant to the persistence of compulsive drug use. Thus, the greatest obstacle to successful development is the gap between the multiplicity of preclinical and early clinical end-points and the regulatory end-point of sustained abstinence. This review proposes two pathways to bridging this gap: further development and validation of the preclinical extended access self-administration model; inclusion of secondary end-points comprising all of the measures highlighted in the present discussion in Phase 3 trials. Further, completion of the postdictive validation of analogous preclinical and clinical assays is of high priority. Ultimately, demonstration of the relevance and validity of a variety of end-points to the ultimate goal of abstinence will allow researchers to identify truly relevant therapeutic mechanisms and intervention targets, and establish a framework for SUD therapeutic development that allows optimal decision-making and resource allocation.

Cocaine analog coupled to disrupted adenovirus: a vaccine strategy to evoke high-titer immunity against addictive drugs

Based on the concept that anticocaine antibodies could prevent inhaled cocaine from reaching its target receptors in the brain, an effective anticocaine vaccine could help reverse cocaine addiction. Leveraging the knowledge that E1(-)E3(-) adenovirus (Ad) gene transfer vectors are potent immunogens, we have developed a novel vaccine platform for addictive drugs by covalently linking a cocaine analog to the capsid proteins of noninfectious, disrupted Ad vector. The Ad-based anticocaine vaccine evokes high-titer anticocaine antibodies in mice sufficient to completely reverse, on a persistent basis, the hyperlocomotor activity induced by intravenous administration of cocaine.

Anti-cocaine vaccine development

Cocaine abuse is an ongoing and serious problem that has led to the growth of a brutal criminal enterprise, particularly in the Americas and Europe. At present, there are no effective pharmacological agents available to treat the addiction by blocking cocaine or reversing its effects. In order to help motivated addicts conquer their addiction, vaccines against cocaine are being developed and one has progressed to clinical trials. This article will discuss the concept of antidrug vaccines in general, the successes and limitations of the various anti-cocaine vaccine approaches, the results of the clinical trials with an anti-cocaine vaccine and some new vaccine-mediated approaches to combat cocaine addiction.

What's new in the treatment of cocaine addiction?

Cocaine dependence continues to be a significant public health problem in the United States. The number of regular cocaine users has not declined significantly in the United States since 1992. Although counseling remains the treatment of choice for cocaine dependence, many cocaine-dependent patients do not respond completely to standard drug counseling. Therefore, the development of new and more effective treatments for cocaine dependence is a research priority. Progress in the understanding of the neurobiology of cocaine dependence has led to the discovery of several promising medications that have already shown encouraging results in controlled clinical trials. Other promising compounds are just becoming available for clinical trials. The use of novel psychosocial techniques such as contingency management seems to increase the efficacy of several medications used to treat cocaine dependence. New medications and new psychosocial techniques are leading to significant improvements in the treatment of cocaine dependence.

Anti-(+)-methamphetamine monoclonal antibody antagonists designed to prevent the progression of human diseases of addiction

Anti-(+)-methamphetamine monoclonal antibodies (mAbs) have the potential to reduce the devastating behavioral and societal effects of the worldwide epidemic of (+)-methamphetamine (METH) addiction and transform the treatment paradigm for diseases of addiction. These novel, protein-based medications could play a vital role in helping patients to achieve sustainable abstinence from METH abuse by serving as an in vivo, around-the-clock sentry against a patient's vulnerability to relapse.

The concept of pharmacologic cocaine interception as a treatment for drug abuse

Cocaine access to brain tissue and associated cocaine-induced behaviors are substantially reduced in rats and mice by significant plasma levels of an enzyme that rapidly metabolizes the drug. Similar results have been obtained in rodents and humans with therapeutic anti-cocaine antibodies, which sequester the drug and prevent its entry into the brain. We show that an efficient cocaine hydrolase can lead to rapid unloading of anti-cocaine antibodies saturated with cocaine, and we provide a theoretical basis for the hypothesis that dual therapy with antibody and hydrolase enzyme may be especially effective.

Active immunotherapy for the Treatment of Cocaine Dependence

Although cocaine is illegal in most countries of the world, addiction is common and increasing in many populations, and the effectiveness of current treatment options for those afflicted has been very limited. The availability of an anti-cocaine vaccine could offer help to those who wish to quit their addiction. A number of vaccines differing in their chemical nature have been developed, and one has advanced into clinical trials. This review will discuss the successes and limitations of the various vaccines and the results of clinical trials of the vaccine using succinyl norcocaine conjugated to cholera toxin B. This latter vaccine shows considerable promise for those individuals whose antibody response is adequate..

Cocaine-specific antibodies blunt the subjective effects of smoked cocaine in humans

BACKGROUND

Rates of relapse among cocaine-dependent patients are high, and new treatment approaches are needed. Clinical data demonstrate that a cocaine vaccine (TA-CD) produces selective anticocaine antibodies, yet the impact of these antibodies on cocaine's direct effects is unknown. The objective of this human laboratory study was to measure the relationship between antibody titers and the effects of smoked cocaine on ratings of intoxication, craving, and cardiovascular effects.

METHODS

Ten cocaine-dependent men not seeking drug treatment spent 2 nights per week for 13 weeks inpatient where the effects of cocaine (0 mg, 25 mg, 50 mg) were determined before vaccination and at weekly intervals thereafter. Two doses of TA-CD (82 microg, n = 4; 360 microg, n = 6) were administered at weeks 1, 3, 5, and 9.

RESULTS

Peak plasma antibody levels, which were highly variable, significantly predicted cocaine's effects. Those individuals in the upper half of antibody production had an immediate (within 4 minutes of cocaine smoking) and robust (55%-81%) reduction in ratings of good drug effect and cocaine quality, while those in the lower half showed only a nonsignificant attenuation (6%-26%). Self-reported cocaine use while participants were outpatient tended to decrease as a function of antibody titer (p < .12). By contrast, higher antibody levels predicted significantly greater cocaine-induced tachycardia.

CONCLUSIONS

The TA-CD vaccine substantially decreased smoked cocaine's intoxicating effects in those generating sufficient antibody. These data support further testing of cocaine immunotherapy as a treatment for cocaine dependence.

Anti-drug vaccines to treat substance abuse

Substance abuse is a growing world-wide problem. The big four drugs of abuse that might lend themselves to immunotherapy are nicotine, cocaine, morphine/heroin and methamphetamine. Tobacco abuse has a well-known enormous impact on major chronic cardiovascular and pulmonary diseases, while the last three, aside from their neuropsychological effects, are illegal, leading to crime and incarceration as well as the transmission of viral diseases. Having an efficient vaccine that would generate antibodies to sequester the drug and prevent its access to the brain could go a long way toward helping a motivated addict quit the addiction. This review will discuss what has been done to bring such vaccines to human use, and what the challenges are for the future of this promising intervention.