Vaccination protects rats from methamphetamine-induced impairment of behavioral responding for food

Vaccines to Treat Substance Use Disorders: Current Status and Future Directions

Addiction, particularly in relation to psychostimulants and opioids, persists as a global health crisis with profound social and economic ramifications. Traditional interventions, including medications and behavioral therapies, often encounter limited success due to the chronic and relapsing nature of addictive disorders. Consequently, there is significant interest in the development of innovative therapeutics to counteract the effects of abused substances. In recent years, vaccines have emerged as a novel and promising strategy to tackle addiction. Anti-drug vaccines are designed to stimulate the immune system to produce antibodies that bind to addictive compounds, such as nicotine, cocaine, morphine, methamphetamine, and heroin. These antibodies effectively neutralize the target molecules, preventing them from reaching the brain and eliciting their rewarding effects. By obstructing the rewarding sensations associated with substance use, vaccines aim to reduce cravings and the motivation to engage in drug use. Although anti-drug vaccines hold significant potential, challenges remain in their development and implementation. The reversibility of vaccination and the potential for combining vaccines with other addiction treatments offer promise for improving addiction outcomes. This review provides an overview of anti-drug vaccines, their mechanisms of action, and their potential impact on treatment for substance use disorders. Furthermore, this review summarizes recent advancements in vaccine development for each specific drug, offering insights for the development of more effective and personalized treatments capable of addressing the distinct challenges posed by various abused substances.

Vaccine development: Current trends and technologies

Despite the effectiveness of vaccination in reducing or eradicating diseases caused by pathogens, there remain certain diseases and emerging infections for which developing effective vaccines is inherently challenging. Additionally, developing vaccines for individuals with compromised immune systems or underlying medical conditions presents significant difficulties. As well as traditional vaccine different methods such as inactivated or live attenuated vaccines, viral vector vaccines, and subunit vaccines, emerging non-viral vaccine technologies, including viral-like particle and nanoparticle vaccines, DNA/RNA vaccines, and rational vaccine design, offer new strategies to address the existing challenges in vaccine development. These advancements have also greatly enhanced our understanding of vaccine immunology, which will guide future vaccine development for a broad range of diseases, including rapidly emerging infectious diseases like COVID-19 and diseases that have historically proven resistant to vaccination. This review provides a comprehensive assessment of emerging non-viral vaccine production methods and their application in addressing the fundamental and current challenges in vaccine development.

The Neurobiology of Methamphetamine Addiction and the Potential to Reduce Misuse Through Conjugate Vaccines Targeting Toll-Like Receptor 4

The methamphetamine epidemic continues to worsen each year and has contributed to more overdose deaths than opioids. Methamphetamine was listed in the top ten lethal drugs in 2021 in the United States. The drug has been shown to cause health problems such as addiction and neurological and behavioral changes. One possible solution to address this crisis is through vaccinations. Vaccinations consist of injecting a controlled substance with the goal of creating compound-specific antibodies. Although still early in development, vaccinations have been found to improve withdrawal symptoms and decrease drug-seeking behavior with minimal health side effects in rodent studies. This paper provides an overview of the clinical presentation and neurobiology of methamphetamine addiction and drug-seeking behaviors. The responses and adverse effects of conjugate vaccines IXTv-100 with adjuvant glucopyranosyl lipid A administered in oil-water stable emulsion and tetanus-toxoid conjugated to succinyl-methamphetamine adsorbed on aluminum hydroxide combined with adjuvant E6020 are examined.

Safety and immunogenicity of the anti-cocaine vaccine UFMG-VAC-V4N2 in a non-human primate model

A promising strategy for cocaine addiction treatment is the anti-drug vaccine. These vaccines induce the production of anticocaine antibodies, capable of linking to cocaine, and decrease the passage of cocaine throughout the blood-brain barrier, decreasing drug activity in the brain. Our research group developed a new vaccine candidate, the UFMG-V4N2, to treat cocaine use disorders (CUD) using an innovative carrier based on calixarenes. This study assessed the safety and immunogenicity of the anti-cocaine vaccine UFMG-VAC-V4N2 in a non-human primate toxicity study using single and multiple vaccine doses. The UFMG-VAC-V4N2 yielded only mild effects in the injection site and did not influence the general health, feeding behavior, or hematological, renal, hepatic, or metabolic parameters in the vaccinated marmosets. The anti-cocaine vaccine UFMG-VAC-V4N2 presented a favorable safety profile and induced the expected immune response in a non-human primate model of Callithrix penicillata. This preclinical UFMG-VAC-V4N2 study responds to the criteria required by international regulatory agencies contributing to future anticocaine clinical trials of this anti-cocaine vaccine.

Immunotherapies for the Treatment of Drug Addiction

Substance use disorders (SUD) are a serious public health concern globally. Existing treatment platforms suffer from a lack of effectiveness. The development of immunotherapies against these substances of abuse for both prophylactic and therapeutic use has gained tremendous importance as an alternative and/or supplementary to existing therapies. Significant development has been made in this area over the last few decades. Herein, we highlight the vaccine and other biologics development strategies, preclinical, clinical updates along with challenges and future directions. Articles were searched in PubMed, ClinicalTrial.gov, and google electronic databases relevant to development, preclinical, clinical trials of nicotine, cocaine, methamphetamine, and opioid vaccines. Various new emerging vaccine development strategies for SUD were also identified through this search and discussed. A good number of vaccine candidates demonstrated promising results in preclinical and clinical phases and support the concept of developing a vaccine for SUD. However, there have been no ultimate success as yet, and there remain some challenges with a massive push to take more candidates to clinical trials for further evaluation to break the bottleneck.

Active and Passive Immunization with an Anti-Methamphetamine Vaccine Attenuates the Behavioral and Cardiovascular Effects of Methamphetamine

BACKGROUND

Methamphetamine use disorder (MUD) is a growing health concern with no FDA-approved treatment. The present series of studies build upon our previous work developing an anti-methamphetamine (MA) vaccine for MUD. We determined the effects of a formulation that included tetanus-toxoid (TT) conjugated to succinyl-methamphetamine (TT-SMA) adsorbed onto aluminum hydroxide (alum) in combination with the novel Toll-Like Receptor-5 agonist, entolimod.

METHODS

Mice were vaccinated (0, 3, 6 weeks) with TT-SMA+alum and various doses of entolimod to determine an optimal dose for enhancing immunogenicity against MA. Functional effects were then assessed using MA-induced locomotor activation in mice. Experiments using passive immunization of antibodies generated by the vaccine tested its ability to attenuate MA-induced cardiovascular effects and alter the reinforcing effects of MA in an MA-induced reinstatement of a drug seeking model of relapse in male and female rats.

RESULTS

Antibody levels peaked at 10 weeks following vaccination with TT-SMA+alum combined with entolimod (1, 3 and 10 μg). MA-induced locomotor activation was significantly attenuated in vaccinated vs. unvaccinated mice and antibody levels significantly correlated with ambulation levels. Passive immunization decreased mean arterial pressure following MA dosing in rats of both sexes but did not alter heart rate. Passive immunization also attenuated the ability of MA to reinstate extinguished drug-seeking behavior in male and female rats. Results support further development of this vaccine for relapse prevention for individuals with MUD.

A Vaccine against Benzimidazole-Derived New Psychoactive Substances That Are More Potent Than Fentanyl

New psychoactive substance (NPS) opioids have proliferated within the international drug market. While synthetic opioids are traditionally composed of fentanyl analogues, benzimidazole-derived isotonitazene and its derivatives are the current NPS opioids of concern. Hence, in this study, we implement immunopharmacotherapy wherein antibodies are produced with high titers and nanomolar affinity to multiple benzimidazole-derived NPS opioids (BNO). Notably, these antibodies blunt psychoactive and physiological repercussions from BNO exposure, which was observed through antinociception, whole-body plethysmography, and blood-brain biodistribution studies. Moreover, we detail previously unreported pharmacokinetics of these drugs, which explains the struggle of traditional pharmaceutical opioid antagonists against BNO substances. These findings provide further insight into the in vivo effects of BNO drugs and the development of effective broad-spectrum therapeutics against NPS opioids.

Immunopharmacotherapeutic advancements in addressing methamphetamine abuse

Methamphetamine (METH) is an illicit psychostimulant that is known to account for substance abuse disorders globally, second only to opioids, yet has no approved pharmacotherapies. Traditional therapies employ small molecule agonists or antagonists for substance use disorders or overdose reversal by targeting drug-specific receptors in the brain. However, the comprehensive mechanism of METH on multiple sites within the central nervous system (CNS) implies its receptors lack the high affinity and specificity required for an "ideal" drug target. The alternative to pharmacotherapies is to sequester abused drugs in the periphery, effectively eliminating the effects from CNS receptor occupation through pharmacokinetic antagonism. This review presents updates on immunopharmacotherapeutic advancements in addressing methamphetamine abuse by focusing on the cultivation of research optimization strategies regarding hapten chemistry, carrier proteins, and adjuvants implemented in active immunization. Furthermore, we discuss necessary developments for each component of active immunopharmacotherapies and the future of active vaccines in treating METH use disorder.

Pharmacokinetics of α-Pyrrolidinovalerophenone in Male Rats with and without Vaccination with an α-Pyrrolidinovalerophenone Vaccine

PURPOSE

α-Pyrrolidinovalerophenone (α-PVP) is a second-generation synthetic cathinone which acts as an inhibitor at the dopamine and norepinephrine transporters in the brain. These novel studies determined the pharmacokinetics (PK) of α-PVP in rats and then evaluated the effects of an α-PVP vaccine on the PK profile.

METHODS

Adult male Sprague-Dawley rats were randomly divided into treatment groups (n = 24/group) in which the vaccinated rats received an initial and two booster immunizations of the α-PVP vaccine at 0, 3, and 9 wks. Control rats received saline injections. α-PVP (0.56, 1, 3 mg/kg, sc) was then administered to both groups between 11-12 weeks and serum samples were collected for determination of α-PVP serum concentrations by LC-MS/MS (n=6 rats/treatment/time). At 13 weeks, brain, heart and kidney concentrations of α-PVP were determined by LC-MS/MS after administration of 1 mg/kg α-PVP (n=4-5 rats/treatment/time).

RESULTS

PK values in control rats showed dose-dependent increases in maximum serum concentrations (Cmax) and area under the curve (AUCinf) values with an elimination half-life (t1/2) of approximately 2.1 h. α-PVP exhibited linear PK profile in control rats. Vaccinated rats had significantly (p<0.05) higher serum Cmax and AUCinf values than controls, and significantly reduced total body clearance, volume of distribution and t1/2 values. Vaccinated rats had significantly lower α-PVP concentrations in the brain, heart, and kidney in comparison to control rats at early time points.

CONCLUSION

Vaccination with the novel α-PVP vaccine significantly altered serum PK leading to a time-dependent reduction in brain, kidney and heart concentrations of α-PVP compared to controls.

Vaccine development against methamphetamine drug addiction

INTRODUCTION

There are currently no effective treatments for Methamphetamine (METH) addiction and psychotherapy remains the sole treatment option. The development of immunopharmacotherapies for the treatment of drug addiction, overdose, and relapse management appears to be promising alternative and a significant body of information has been generated using various vaccine development strategies. Herein, we present an update on the developments toward anti-METH vaccines and their study outcomes in preclinical and clinical studies.

AREAS COVERED

The scope of this article is to present an update on METH vaccine development strategies such as active vaccination through hapten design and the passive immunization through monoclonal antibodies along with preclinical and clinical studies. The relevant literatures and clinical trial outcomes were searched in databases including Google, Google Scholar, PubMed, Science Direct, ClinicalTrials.gov, and www.anzctr.org.au using specific keywords.

EXPERT OPINION

Significant improvements have been developed for immunopharmacotherapies for METH addiction over the last two decades. However, only one monoclonal antibody candidate has been evaluated in a phase I clinical trial. At this moment, it is essential to evaluate the safety and efficacy of potential candidates in clinical trials to validate the importance of this platform drug-vaccine conjugation in order to manage or overcome METH addiction.

Emerging Concepts and Technologies in Vaccine Development

Despite the success of vaccination to greatly mitigate or eliminate threat of diseases caused by pathogens, there are still known diseases and emerging pathogens for which the development of successful vaccines against them is inherently difficult. In addition, vaccine development for people with compromised immunity and other pre-existing medical conditions has remained a major challenge. Besides the traditional inactivated or live attenuated, virus-vectored and subunit vaccines, emerging non-viral vaccine technologies, such as viral-like particle and nanoparticle vaccines, DNA/RNA vaccines, and rational vaccine design, offer innovative approaches to address existing challenges of vaccine development. They have also significantly advanced our understanding of vaccine immunology and can guide future vaccine development for many diseases, including rapidly emerging infectious diseases, such as COVID-19, and diseases that have not traditionally been addressed by vaccination, such as cancers and substance abuse. This review provides an integrative discussion of new non-viral vaccine development technologies and their use to address the most fundamental and ongoing challenges of vaccine development.

Active vaccination reduces reinforcing effects of MDPV in male Sprague-Dawley rats trained to self-administer cocaine

RATIONALE

3,4-Methylenedioxypyrovalerone (MDPV) is a synthetic cathinone abused for its cocaine-like psychostimulant effects in "bath salts" products. While there are currently no pharmacotherapies for MDPV abuse, rodent studies suggest immunotherapy may offer a feasible treatment option.

OBJECTIVES

These studies tested the capacity of active vaccination to reduce the reinforcing effects of MDPV in Sprague-Dawley rats.

METHODS

Rats acquired cocaine self-administration (0.32 mg/kg/inf) on an FR1 schedule. Dose-effect functions for cocaine (0.032-1.0 mg/kg/inf) and MDPV (0.001-0.32 mg/kg/inf) were determined under an FR5 schedule. Rats in the vaccine group were immunized during cocaine self-administration. All rats transitioned to a progressive-ratio (PR) schedule to establish breakpoints for cocaine (0.1-1.0 mg/kg/inf) and MDPV (0.01-0.32 mg/kg/inf). Responding was extinguished, and cue-induced and MDPV-primed reinstatement (0.56 mg/kg, IP) were evaluated.

RESULTS

No endpoints of cocaine self-administration differed between groups, but the ED₅₀ for MDPV self-administration was significantly lower in control relative to vaccinated rats. Under the PR schedule, MDPV was ~ 2.5-fold more potent in maintaining responding in control than vaccinated rats, but E_max was not different between groups. Vaccination did not reduce MDPV-primed reinstatement, perhaps due to a decrease in antibody titer.

CONCLUSIONS

Vaccination did not alter acquisition of cocaine self-administration, demonstrating pharmacological selectivity and suggesting that the vaccine did not affect learning or motivation, while effectively reducing the potency of MDPV as a reinforcer. The protective effects of the vaccine were surmounted by large unit doses of MDPV, suggesting maximal efficacy of drug-conjugate vaccines in substance abuse disorders will likely require concurrent behavior modification therapy.

Designer drugs: a medicinal chemistry perspective (II)

During 2012-2018, the clandestine manufacture of new psychoactive substances (NPS) designed to circumvent substance control regulations increased exponentially worldwide, with concomitant increase in fatalities. This review focuses on three compound classes identified as synthetic opioids, synthetic amphetamines, and synthetic cannabinoids and highlights the medicinal chemistry precedents utilized by clandestine laboratories to develop new NPS with increased brain penetration, longer duration of action, and greater potency. Chemical approaches to illicit drug abuse treatment options, particularly for opioid use disorder, are also discussed.

Effects of a methamphetamine vaccine, IXT-v100, on methamphetamine-related behaviors

RATIONALE

Vaccines have been developed as a potential treatment for methamphetamine (meth) use disorder (MUD). Immunization with the meth vaccine IXT-v100 has previously been shown to elicit antibodies with high affinity for meth and thus may be an effective treatment for MUD.

OBJECTIVES

These studies were designed to determine the efficacy of IXT-v100 on meth-taking and meth-seeking behaviors in rats.

METHODS

In the acquisition and maintenance study, male and female rats were trained to self-administer meth (0.06 mg/kg/infusion) over an 8-week period following vaccination. In the last 4 weeks, the dose of meth was increased or decreased each week. To assess meth-seeking behavior, the meth-primed reactivity model was used. Rats were trained to self-administer meth for 5 weeks, followed by a 5-week or 11-week forced abstinence period during which the animals were vaccinated. Rats were then placed back into the self-administration chamber immediately after being injected with meth (1 mg/kg, i.p.) but did not receive meth during the session. Responses were recorded and used as a measure of meth seeking.

RESULTS

Results from the acquisition and maintenance study in Wistar rats show that vaccination with IXT-v100 adjuvanted with glucopyranosyl lipid A stable emulsion decreases the percentage of animals that will self-administer a moderate level of meth. In the meth-primed reactivity studies, results from males showed that vaccination significantly attenuates meth-seeking behavior.

CONCLUSION

Together, these results suggest vaccination with IXT-v100 may be effective at decreasing meth-taking and meth-seeking behaviors in humans suffering with MUD.

Antibody production and pharmacokinetics of METH in rats following vaccination with the METH vaccine, IXT-v100, adjuvanted with GLA-SE

BACKGROUND

Methamphetamine use disorder continues to be inadequately treated, but improvements are being made in the field of immunotherapeutics, including vaccines, which could provide new options for treatment. Cocaine and nicotine vaccines have been tested clinically, but have yet to elicit the necessary antibody concentrations required to be effective. Methamphetamine vaccines have been tested in multiple nonclinical models and appear promising. Improved adjuvants have the potential to further stimulate the immune system to reach effective levels of antibodies. Previously, the methamphetamine vaccine IXT-v100 was administered with GLA-SE, a toll-like receptor 4 agonist, in mice to produce higher levels of antibodies than when it was administered with two other widely used adjuvants, Alhydrogel and Sigma Adjuvant System.

METHODS

The purpose of this research was to evaluate IXT-v100, given in combination with the adjuvant GLA-SE, to determine its efficacy in antagonizing methamphetamine disposition in a rat pharmacokinetic study. Additional rat studies were conducted to compare the ability of IXT-v100 manufactured with greater hapten densities to elicit higher antibody levels.

RESULTS

As expected based on prior studies with anti-methamphetamine monoclonal antibodies, the antibodies resulting from vaccination with IXT-v100 altered methamphetamine pharmacokinetics by increasing serum concentrations and extending the half-life. Furthermore, intentional variations in the ratio of components during manufacturing led to production of vaccines with higher hapten densities. The higher hapten densities resulted in production of antibodies that maintained the ability to bind methamphetamine with high affinity.

CONCLUSIONS

The results support continued development of IXT-v100 for the treatment of methamphetamine use disorder.

Design, synthesis and biological evaluation of a bi-specific vaccine against α-pyrrolidinovalerophenone (α-PVP) and 3,4-methylenedioxypyrovalerone (MDPV) in rats

α-PVP (α-pyrrolidinovalerophenone) and MDPV (3,4-methylenedioxypyrovalerone) are potent abused stimulants that are members of the synthetic cathinone class of drugs. Although these drugs are taken with recreational intent, high doses can lead to unintended adverse effects including agitation, cardiovascular effects, sympathomimetic syndromes, hallucinations, and psychoses. One possible treatment is the use of a vaccine to block or attenuate adverse medical effects. These studies report the preparation of a vaccine that generates high affinity antibodies specific for both drugs and the pharmacological testing of this vaccine in male rats. Alkylation of a hydroxy-α-PVP analog with an appropriate thiol-bearing linker afforded the hapten. When hapten-conjugated carrier protein was mixed with adjuvant, the resulting vaccine stimulated production of antibodies in male Sprague Dawley rats that were found to significantly reduce α-PVP- and MDPV-induced hyperlocomotion as well as to significantly reduce the concentrations of MDPV drugs in critical organs. The novel vaccine produced high affinity antibodies against MDPV, (R)-MDPV, (S)-MDPV, and α-PVP. Cross-reactivity testing against nine structurally similar cathinones showed very limited binding, and no binding to off-target endogenous and exogenous compounds. Antibodies generated by this bi-specific vaccine also significantly shortened the duration of locomotor activity induced by both drugs up to a dose of 5.6 mg/kg in male rats.

Consequence of Hapten Stereochemistry: An Efficacious Methamphetamine Vaccine

Recent trends in methamphetamine (METH) misuse and overdose suggest society is inadvertently overlooking a brewing METH crisis. In the past decade, psychostimulant-related lethal overdoses and hospitalizations have skyrocketed 127 and 245%, respectively. Unlike the opioid crisis, no pharmaceutical interventions are available for treating METH use disorder or reversing overdose. Herein, we report the first active vaccine that offers protection from lethal (+)-METH challenge in male Swiss Webster mice. This vaccine formulation of (S)MLMH-TT adjuvanted with CpG ODN 1826 + alum successfully raised anti-METH antibodies in high titers, reduced (+)-METH distribution to the brain, and lowered (+)-METH-associated stereotypies in a hyperlocomotion assay. A comparison of enantiomeric haptens and the racemate elucidated the importance of employing (S)-stereochemistry in METH hapten design for optimal protection.

Monoclonal Antibodies for Combating Synthetic Opioid Intoxication

Opioid abuse in the United States has been declared a national crisis and is exacerbated by an inexpensive, readily available, and illicit supply of synthetic opioids. Specifically, fentanyl and related analogues such as carfentanil pose a significant danger to opioid users due to their high potency and rapid acting depression of respiration. In recent years these synthetic opioids have become the number one cause of drug-related deaths. In our research efforts to combat the public health threat posed by synthetic opioids, we have developed monoclonal antibodies (mAbs) against the fentanyl class of drugs. The mAbs were generated in hybridomas derived from mice vaccinated with a fentanyl conjugate vaccine. Guided by a surface plasmon resonance (SPR) binding assay, we selected six hybridomas that produced mAbs with 10^-11 M binding affinity for fentanyl, yet broad cross-reactivity with related fentanyl analogues. In mouse antinociception models, our lead mAb (6A4) could blunt the effects of both fentanyl and carfentanil in a dose-responsive manner. Additionally, mice pretreated with 6A4 displayed enhanced survival when subjected to fentanyl above LD₅₀ doses. Pharmacokinetic analysis revealed that the antibody sequesters large amounts of these drugs in the blood, thus reducing drug biodistribution to the brain and other tissue. Lastly, the 6A4 mAb could effectively reverse fentanyl/carfentanil-induced antinociception comparable to the opioid antagonist naloxone, the standard of care drug for treating opioid overdose. While naloxone is known for its short half-life, we found the half-life of 6A4 to be approximately 6 days in mice, thus monoclonal antibodies could theoretically be useful in preventing renarcotization events in which opioid intoxication recurs following quick metabolism of naloxone. Our results as a whole demonstrate that monoclonal antibodies could be a desirable treatment modality for synthetic opioid overdose and possibly opioid use disorder.

Preclinical efficacy of an anti-methamphetamine vaccine using E6020 adjuvant

BACKGROUND AND OBJECTIVE

Methamphetamine (MA) substance use disorder (SUD) does not have an efficacious pharmacotherapy. We developed a MA vaccine and investigated its potential to attenuate MA induced responses.

METHODS

We examined a novel adjuvant, E6020, a Toll-like receptor-4 (TLR-4) agonist combined with tetanus-toxoid conjugated to succinyl-methamphetamine (TT-SMA) adsorbed on aluminum hydroxide (alum). Adult BALB/c female mice received the vaccine and booster injections at weeks 0, 3, and 6. The efficacy of the vaccine was assessed by the level and affinity of anti-MA antibodies elicited, its ability to attenuate MA induced locomotor activation and its reduction in the amount of MA entering the brains of vaccinated mice.

RESULTS

The TT-SMA vaccine containing alum and E6020 adjuvant produced anti-MA antibodies with nanomolar affinities and showed threefold greater peak titer levels than without E6020 (700 vs 250 μg/ml). These antibodies significantly decreased MA-induced locomotor activation (p < .05), and reduced the brain (p < .005) MA levels following MA administration in actively immunized mice.

CONCLUSIONS

Thus, this anti-MA vaccine formulated with E6020 demonstrated effective functional protection against behavioral disruptions induced by MA.

SCIENTIFIC SIGNIFICANCE

Together, anti-MA vaccine showing a promising improvement in the efficacy of the vaccine that could be an effective candidate vaccine for methamphetamine use disorder (MUD). Furthermore, combinations of adjuvants may be a tool to design vaccines for MA dependence in humans. (Am J Addict 2019;XX:1-8).

Novel technologies in detection, treatment and prevention of substance use disorders

Substance use disorders are a widely recognized problem, which affects various levels of communities and influenced the world socioeconomically. Its source is deeply embedded in the global population. In order to fight against such an adversary, governments have spared no efforts in implementing substance abuse treatment centers and funding research to develop treatments and prevention procedures. In this review, we will discuss the use of immunological-based treatments and detection kit technologies. We will be detailing the steps followed to produce performant antibodies (antigens, carriers, and adjuvants) focusing on cocaine and methamphetamine as examples. Furthermore, part of this review is dedicated to substance use detection. Owing to novel technologies such as bio-functional polymeric surfaces and biosensors manufacturing, detection has become a more convenient method with the fast and on-site developed devices. Commercially available devices are able to test substance use disorders in urine, saliva, hair, and sweat. This improvement has had a tremendous impact on the prevention of driving under influence and other illicit behaviors. Lastly, substance abuse became a major issue involving the cooperation of experts on all levels to devise better treatment programs and prevent abuse-based accidents, injury and death.

Conjugate Vaccine Immunotherapy for Substance Use Disorder

Substance use disorder, especially in relation to opioids such as heroin and fentanyl, is a significant public health issue and has intensified in recent years. As a result, substantial interest exists in developing therapeutics to counteract the effects of abused drugs. A promising universal strategy for antagonizing the pharmacology of virtually any drug involves the development of a conjugate vaccine, wherein a hapten structurally similar to the target drug is conjugated to an immunogenic carrier protein. When formulated with adjuvants and immunized, the immunoconjugate should elicit serum IgG antibodies with the ability to sequester the target drug to prevent its entry to the brain, thereby acting as an immunoantagonist. Despite the failures of first-generation conjugate vaccines against cocaine and nicotine in clinical trials, second-generation vaccines have shown dramatically improved performance in preclinical models, thus renewing the potential clinical utility of conjugate vaccines in curbing substance use disorder. This review explores the critical design elements of drug conjugate vaccines such as hapten structure, adjuvant formulation, bioconjugate chemistry, and carrier protein selection. Methods for evaluating these vaccines are discussed, and recent progress in vaccine development for each drug is summarized.

Construction of an enantiopure bivalent nicotine vaccine using synthetic peptides

Clinical outcomes of anti-nicotine vaccines may be improved through enhancements in serum antibody affinity and concentration. Two strategies were explored to improve vaccine efficacy in outbred mice: the use of enantiopure haptens and formulation of a bivalent vaccine. Vaccines incorporating natural (-) nicotine haptens improved relative antibody affinities >10-fold over (+) haptens, stimulated a two-fold boost in nicotine serum binding capacity, and following injection with 3 cigarette equivalents of nicotine, prevented a larger proportion of nicotine (>85%) from reaching the brain. The activity of a bivalent vaccine containing (-) 3’AmNic and (-) 1’SNic haptens was then compared to dose-matched monovalent groups. It was confirmed that antisera generated by these structurally distinct haptens have minimal cross-reactivity and stimulate different B cell populations. Equivalent antibody affinities were detected between the three groups, but the bivalent group showed two-fold higher titers and an additive increase in nicotine serum binding capacity as compared to the monovalent groups. Mice immunized with the bivalent formulation also performed better in a nicotine challenge experiment, and prevented >85% of a nicotine dose equivalent to 12 cigarettes from reaching the brain. Overall, enantiopure conjugate vaccines appear to improve serum antibody affinity, while multivalent formulations increase total antibody concentration. These findings may help improve the performance of future clinical candidate vaccines.

Effective active vaccination against methamphetamine in female rats

BACKGROUND

Immunotherapies directed against methamphetamine (MA) abuse have shown success in rodent models, however only a limited number of studies have investigated active vaccination in female mice and none in female rats. It is critical to determine if potential immunotherapeutic strategies generalize across sex, particularly for drugs that may produce significant sex-differences on behavioral or physiological endpoints.

METHODS

Female Wistar rats were initially vaccinated with keyhole-limpet hemocyanin (KLH) or an anti-methamphetamine-KLH conjugate (MH6-KLH) three times over five weeks and implanted with radiotelemetry devices to assess locomotor activity and body temperature responses to MA. Rats were first exposed to MA via vapor inhalation (100mg/mL in propylene glycol) and then by injection (0.25-1.0mg/kg, i.p.) and vapor after a final vaccine boost.

RESULTS

The MH6-KLH vaccine generated an increase in antibody titers across the initial 6-week, 3 immunization protocol and a restoration of titer after a week 14 booster. Locomotor stimulation induced by 0.25mg/kg MA, i.p, in the KLH group was prevented in the MH6-KLH group. MH6-KLH animals also exhibited an attenuated locomotor stimulation produced by 0.5mg/kg MA, i.p. No group differences in locomotion induced by vapor inhalation of MA were observed and body temperature was not differentially affected by MA across the groups, most likely because vapor inhalation of MA that produced similar locomotor stimulation resulted in ∼10-fold higher plasma MA levels.

CONCLUSIONS

This study confirms the efficacy of the MH6-KLH vaccine in attenuating the effects of MA in female rats.

Pharmacotherapeutic agents in the treatment of methamphetamine dependence

INTRODUCTION

Methamphetamine use is a serious public health concern in many countries and is second to cannabis as the most widely abused illicit drug in the world. Effective management for methamphetamine dependence remains elusive and the large majority of methamphetamine users relapse following treatment. Areas covered: Progression in the understanding of the pharmacological basis of methamphetamine use has provided us with innovative opportunities to develop agents to treat dependence. The current review summarizes relevant literature on the neurobiological and clinical correlates associated with methamphetamine use. We then outline agents that have been explored for potential treatments in preclinical studies, human laboratory phase I and phase II trials over the last ten years. Expert opinion: No agent has demonstrated a broad and strong effect in achieving MA abstinence in Phase II trials. Agents with novel therapeutic targets appear promising. Advancement in MA treatment, including translation into practice, faces several clinical challenges.

Biologics to treat substance use disorders: Current status and new directions

Biologics (vaccines, monoclonal antibodies (mAb), and genetically modified enzymes) offer a promising class of therapeutics to treat substance use disorders (SUD) involving abuse of opioids and stimulants such as nicotine, cocaine, and methamphetamine. In contrast to small molecule medications targeting brain receptors, biologics for SUD are larger molecules that do not cross the blood-brain barrier (BBB), but target the drug itself, preventing its distribution to the brain and blunting its effects on the central nervous system (CNS). Active and passive immunization approaches rely on antibodies (Ab) that bind drugs of abuse in serum and block their distribution to the brain, preventing the rewarding effects of drugs and addiction-related behaviors. Alternatives to vaccines and anti-drug mAb are genetically engineered human or bacterial enzymes that metabolize drugs of abuse, lowering the concentration of free active drug. Pre-clinical and clinical data support development of effective biologics for SUD.

Methamphetamine Vaccines: Improvement through Hapten Design

Methamphetamine (MA) addiction is a serious public health problem, and current methods to abate addiction and relapse are currently ineffective for mitigating this growing global epidemic. Development of a vaccine targeting MA would provide a complementary strategy to existing behavioral therapies, but this has proven challenging. Herein, we describe optimization of both hapten design and formulation, identifying a vaccine that elicited a robust anti-MA immune response in mice, decreasing methamphetamine-induced locomotor activity.

Optimization of a methamphetamine conjugate vaccine for antibody production in mice

There are still no approved medications for treating patients who abuse methamphetamine. Active vaccines for treating abuse of nicotine and cocaine are in clinical studies, but have not proven effective seemingly due to inadequate anti-drug antibody production. The current studies aimed to optimize the composition, adjuvant and route of administration of a methamphetamine conjugate vaccine, ICKLH-SMO9, in mice with the goal of generating significantly higher antibody levels. A range of hapten epitope densities were compared, as were the adjuvants Alhydrogel and a new Toll-like receptor 4 (TLR4) agonist called GLA-SE. While methamphetamine hapten density did not strongly affect the antibody response, the adjuvant did. Glucopyranosyl lipid A in a stable oil-in-water emulsion (GLA-SE) produced much higher levels of antibody in response to immunization compared with Alhydrogel; immunization with GLA-SE also produced antibodies with higher affinities for methamphetamine. GLA-SE has been used in human studies of vaccines for influenza among others and like some other clinical TLR4 agonists, it is safe and elicits a strong immune response. GLA-SE adjuvanted vaccines are typically administered by intramuscular injection and this also proved effective in these mouse studies. Clinical studies of the ICKLH-SMO9 methamphetamine vaccine adjuvanted with GLA-SE have the potential for demonstrating efficacy by generating much higher levels of antibody than substance abuse vaccines that have unsuccessfully used aluminum-based adjuvants.

Animal Models and the Development of Vaccines to Treat Substance Use Disorders

The development of pharmacotherapies for substance use disorders (SUDs) is a high priority in addiction research. At present, there are no approved pharmacotherapies for cocaine and methamphetamine use disorders, while treatments for nicotine and opioid use are moderately effective. Indeed, many of these treatments can cause adverse drug side effects and have poor medication compliance, which often results in increased drug relapse rates. An alternative to these traditional pharmacological interventions is immunotherapy or vaccines that can target substances associated with SUDs. In this chapter, we discuss the current knowledge on the efficacy of preclinical vaccines, particularly immunogens that target methamphetamine, cocaine, nicotine, or opioids to attenuate drug-induced behaviors in animal models of SUDs. We also review vaccines (and antibodies) against cocaine, nicotine, and methamphetamine that have been assessed in human clinical trials. While preclinical studies indicate that several vaccines show promise, these findings have not necessarily translated to the clinical population. Thus, continued effort to design more effective vaccine immunogens using SUD animal models is necessary in order to support the use of immunotherapy as a viable option for individuals with SUDs.

Combatting Synthetic Designer Opioids: A Conjugate Vaccine Ablates Lethal Doses of Fentanyl Class Drugs

Fentanyl is an addictive prescription opioid that is over 80 times more potent than morphine. The synthetic nature of fentanyl has enabled the creation of dangerous "designer drug" analogues that escape toxicology screening, yet display comparable potency to the parent drug. Alarmingly, a large number of fatalities have been linked to overdose of fentanyl derivatives. Herein, we report an effective immunotherapy for reducing the psychoactive effects of fentanyl class drugs. A single conjugate vaccine was created that elicited high levels of antibodies with cross-reactivity for a wide panel of fentanyl analogues. Moreover, vaccinated mice gained significant protection from lethal fentanyl doses. Lastly, a surface plasmon resonance (SPR)-based technique was established enabling drug-specificity profiling of antibodies derived directly from serum. Our newly developed fentanyl vaccine and analytical methods may assist in the battle against synthetic opioid abuse.

Is immunotherapy an opportunity for effective treatment of drug addiction?

Immunotherapy has a great potential of becoming a new therapeutic strategy in the treatment of addiction to psychoactive drugs. It may be used to treat addiction but also to prevent neurotoxic complications of drug overdose. In preclinical studies two immunological methods have been tested; active immunization, which relies on the administration of vaccines and passive immunization, which relies on the administration of monoclonal antibodies. Until now researchers have succeeded in developing vaccines and/or antibodies against addiction to heroin, cocaine, methamphetamine, nicotine and phencyclidine. Their effectiveness has been confirmed in preclinical studies. At present, clinical studies are being conducted for vaccines against nicotine and cocaine and also anti-methamphetamine monoclonal antibody. These preclinical and clinical studies suggest that immunotherapy may be useful in the treatment of addiction and drug overdose. However, there are a few problems to be solved. One of them is controlling the level of antibodies due to variability between subjects. But even obtaining a suitable antibody titer does not guarantee the effectiveness of the vaccine. Additionally, there is a risk of intentional or unintentional overdose. As vaccines prevent passing of drugs through the blood/brain barrier and thereby prevent their positive reinforcement, some addicted patients may erroneously seek higher doses of psychoactive substances to get "high". Consequently, vaccination should be targeted at persons who have a strong motivation to free themselves from drug dependency. It seems that immunotherapy may be an opportunity for effective treatment of drug addiction if directed to adequate candidates for treatment. For other addicts, immunotherapy may be a very important element supporting psycho- and pharmacotherapy.

Effects of active anti-methamphetamine vaccination on intravenous self-administration in rats

BACKGROUND

d-Methamphetamine (METH) addiction is a serious public health concern for which successful treatment remains elusive. Immunopharmacotherapy has been shown to attenuate locomotor and thermoregulatory effects of METH. The current study investigated whether active vaccination against METH could alter intravenous METH self-administration in rats.

METHODS

Male Sprague-Dawley rats (Experiment 1: N=24; Experiment 2: N=18) were vaccinated with either a control keyhole-limpet hemocyanin conjugate vaccine (KLH) or a candidate anti-METH vaccine (MH6-KLH) or. Effects of vaccination on the acquisition of METH self-administration under two dose conditions (0.05, 0.1mg/kg/inf) and post-acquisition dose-substitution (0, 0.01, 0.05, 0.20mg/kg/inf, Experiment 1; 0.01, 0.05, 0.10, 0.15mg/kg/inf, Experiment 2) during steady-state responding were investigated. Plasma METH concentrations were determined 30min after an acute challenge dose of 3.2mg/kg METH.

RESULTS

Active vaccination inhibited the acquisition of METH self-administration under the 0.1mg/kg/inf dose condition, with 66% of the MH6-KLH-vaccinated rats compared to 100% of the controls reaching criteria, and produced transient and dose-dependent effects on self-administration during the maintenance phase. Under the 0.05mg/kg/inf dose condition, MH6-KLH-vaccinated rats initially self-administered more METH than controls, but then self-administration decreased across the acquisition phase relative to controls; a subsequent dose-response assessment confirmed that MH6-KLH-vaccinated rats failed to acquire METH self-administration. Finally, plasma METH concentrations were higher in MH6-KLH-vaccinated rats compared to controls after an acute METH challenge, and these were positively correlated with antibody titers.

CONCLUSIONS

These data demonstrate that active immunopharmacotherapy for METH attenuates the acquisition of METH self-administration.

Immunotherapy Applied to Neuropsychiatric Disorders: a New Perspective of Treatment

Manipulation of the immunological system has lead to groundbreaking discoveries that have had deep impact in demographic and health worldwide. Newer research has made it clear that immunological treatment of neurological and neuropsychiatric diseases may present itself as a viable solution to many ailments. In this mini-review, results of immunotherapeutic studies are presented, indicating that this field may be important in elucidating the etiology of many neurological conditions, and presenting a therapeutic alternative to current treatments.

Combining Active Immunization with Monoclonal Antibody Therapy To Facilitate Early Initiation of a Long-Acting Anti-Methamphetamine Antibody Response

We hypothesized that an anti-METH mAb could be used in combination with a METH-conjugate vaccine (MCV) to safely improve the overall quality and magnitude of the anti-METH immune response. The benefits would include immediate onset of action (from the mAb), timely increases in the immune responses (from the combined therapy) and duration of antibody response that could last for months (from the MCV). A novel METH-like hapten (METH-SSOO9) was synthesized and then conjugated to immunocyanin monomers of keyhole limpet hemocyanin (IC(KLH)) to create the MCV ICKLH-SOO9. The vaccine, in combination with previously discovered anti-METH mAb7F9, was then tested in rats for safety and potential efficacy. The combination antibody therapy allowed safe achievement of an early high anti-METH antibody response, which persisted throughout the study. Indeed, even after 4 months the METH vaccine antibodies still had the capacity to significantly reduce METH brain concentrations resulting from a 0.56 mg/kg METH dose.

Impact of methamphetamine on infection and immunity

The prevalence of methamphetamine (METH) use is estimated at ~35 million people worldwide, with over 10 million users in the United States. METH use elicits a myriad of social consequences and the behavioral impact of the drug is well understood. However, new information has recently emerged detailing the devastating effects of METH on host immunity, increasing the acquisition of diverse pathogens and exacerbating the severity of disease. These outcomes manifest as modifications in protective physical and chemical defenses, pro-inflammatory responses, and the induction of oxidative stress pathways. Through these processes, significant neurotoxicities arise, and, as such, chronic abusers with these conditions are at a higher risk for heightened consequences. METH use also influences the adaptive immune response, permitting the unrestrained development of opportunistic diseases. In this review, we discuss recent literature addressing the impact of METH on infection and immunity, and identify areas ripe for future investigation.

Simple radiometric method for accurately quantitating epitope densities of hapten-protein conjugates with sulfhydryl linkages

Control of small molecule hapten epitope densities on antigenic carrier proteins is essential for development and testing of optimal conditions for vaccines. Yet, accurate determination of epitope density can be extremely difficult to accomplish, especially with the use of small haptens, large molecular weight carrier proteins, and limited amounts of protein. Here we report a simple radiometric method that uses ¹⁴C-labeled cystine to measure hapten epitope densities during sulfhydryl conjugation of haptens to maleimide activated carrier proteins. The method was developed using a (+)-methamphetamine (METH)-like hapten with a sulfhydryl terminus, and two prototype maleimide activated carrier proteins, bovine serum albumin (BSA) and immunocyanin monomers of keyhole limpet hemocyanin. The method was validated by immunochemical analysis of the hapten–BSA conjugates, and least-squares linear regression analysis of epitope density values determined by the new radiometric method versus values determined by matrix-assisted laser desorption/ionization mass spectrometry. Results showed that radiometric epitope density values correlated extremely well with the mass spectrometrically derived values (r² = 0.98, y = 0.98x + 0.91). This convenient and simple method could be useful during several stages of vaccine development including the optimization and monitoring of conditions for hapten–protein conjugations, and choosing the most effective epitope densities for conjugate vaccines.

Treatment of rats with an anti-(+)-methamphetamine monoclonal antibody shortens the duration of action of repeated (+)-methamphetamine challenges over a one month period

This study assessed clinical scenarios of continuing monoclonal antibody (mAb) treatment for (+)-methamphetamine (METH) addiction, and the implications of missing or discontinuing this therapy. We hypothesized that chronic anti-METH mAb7F9 (METH KD=9 nM) treatment of rats could significantly decrease METH-induced behaviors; even with repeated METH challenges, use of METH doses in excess of mAb binding sites, and after discontinuing mAb treatment which results in a 10-fold reduction in mAb7F9 serum concentrations. Male Sprague Dawley rats (n=6/group) were treated with i.v. saline or a loading dose of mAb7F9 to achieve instant steady-state conditions followed by two weekly (141 mg/kg) doses ending on day 14. METH (0.56 mg/kg) was administered 4h and three days after each saline or mAb7F9 treatment, and on day 21. This produced locomotion and rearing behavior that lasted about 120 min in control rats. In mAb7F9 treated rats, METH-induced distance traveled was significantly reduced from 60 to 120 min (P<0.05) on days 0-21 and rearing was significantly reduced from 60 to 120 min on days 0-17. METH serum concentrations determined 5h after METH dosing was significantly increased in mAb7F9-treated rats after all METH challenges. On days 24 and 28 (the final day), the rats were administered a 3-fold higher METH dose (1.68 mg/kg). MAb7F9 treated rats showed a substantially earlier termination of the METH-induced locomotion on both days, even though the METH dose exceeded mAb7F9s binding capacity. METH brain concentrations determined 5h after METH on day 28 were also significantly decreased in mAb7F9-treated rats. In conclusion, over one month, mAb7F9 significantly and continuously bound METH and reduced METH-induced locomotor effects even after discontinuation of mAb treatment and challenge with higher METH doses.

Adjuvants for vaccines to drugs of abuse and addiction

Immunotherapeutic vaccines to drugs of abuse, including nicotine, cocaine, heroin, oxycodone, methamphetamine, and others are being developed. The theoretical basis of such vaccines is to induce antibodies that sequester the drug in the blood in the form of antibody-bound drug that cannot cross the blood brain barrier, thereby preventing psychoactive effects. Because the drugs are haptens a successful vaccine relies on development of appropriate hapten-protein carrier conjugates. However, because induction of high and prolonged levels of antibodies is required for an effective vaccine, and because injection of T-independent haptenic drugs of abuse does not induce memory recall responses, the role of adjuvants during immunization plays a critical role. As reviewed herein, preclinical studies often use strong adjuvants such as complete and incomplete Freund's adjuvant and others that cannot be, or in the case of many newer adjuvants, have never been, employed in humans. Balanced against this, the only adjuvant that has been included in candidate vaccines in human clinical trials to nicotine and cocaine has been aluminum hydroxide gel. While aluminum salts have been widely utilized worldwide in numerous licensed vaccines, the experience with human responses to aluminum salt-adjuvanted vaccines to haptenic drugs of abuse has suggested that the immune responses are too weak to allow development of a successful vaccine. What is needed is an adjuvant or combination of adjuvants that are safe, potent, widely available, easily manufactured, and cost-effective. Based on our review of the field we recommend the following adjuvant combinations either for research or for product development for human use: aluminum salt with adsorbed monophosphoryl lipid A (MPLA); liposomes containing MPLA [L(MPLA)]; L(MPLA) adsorbed to aluminum salt; oil-in-water emulsion; or oil-in-water emulsion containing MPLA.

Vaccines against drugs of abuse: where are we now?

Drug addiction is a serious problem worldwide. One therapy being investigated is vaccines against drugs of abuse. The antibodies elicited against the drug can take up the drug and prevent it from reaching the reward centers in the brain. Few such vaccines have entered clinical trials, but research is going on apace. Many studies are very promising and more clinical trials should be coming out in the near future.

Treatment with a monoclonal antibody against methamphetamine and amphetamine reduces maternal and fetal rat brain concentrations in late pregnancy

We hypothesized that treatment of pregnant rat dams with a dual reactive monoclonal antibody (mAb4G9) against (+)-methamphetamine [METH; equilibrium dissociation rate constant (KD) = 16 nM] and (+)-amphetamine (AMP; KD = 102 nM) could confer maternal and fetal protection from brain accumulation of both drugs of abuse. To test this hypothesis, pregnant Sprague-Dawley rats (on gestational day 21) received a 1 mg/kg i.v. METH dose, followed 30 minutes later by vehicle or mAb4G9 treatment. The mAb4G9 dose was 0.56 mole-equivalent in binding sites to the METH body burden. Pharmacokinetic analysis showed baseline METH and AMP elimination half-lives were congruent in dams and fetuses, but the METH volume of distribution in dams was nearly double the fetal values. The METH and AMP area under the serum concentration-versus-time curves from 40 minutes to 5 hours after mAb4G9 treatment increased >7000% and 2000%, respectively, in dams. Fetal METH serum did not change, but AMP decreased 23%. The increased METH and AMP concentrations in maternal serum resulted from significant increases in mAb4G9 binding. Protein binding changed from ∼15% to > 90% for METH and AMP. Fetal serum protein binding appeared to gradually increase, but the absolute fraction bound was trivial compared with the dams. mAb4G9 treatment significantly reduced METH and AMP brain values by 66% and 45% in dams and 44% and 46% in fetuses (P < 0.05), respectively. These results show anti-METH/AMP mAb4G9 therapy in dams can offer maternal and fetal brain protection from the potentially harmful effects of METH and AMP.