A Review of Immunotherapeutic Approaches for Substance Use Disorders: Current Status and Future Prospects

Antibody immunotherapies for personalized opioid addiction treatment

Approved therapies for managing opioid addiction involve intensive treatment regimens which remain both costly and ineffective. As pharmaceutical interventions have achieved variable success treating substance use disorders (SUD), alternative therapeutics must be considered. Antidrug antibodies induced by vaccination or introduced as monoclonal antibody formulations can neutralize or destroy opioids in circulation before they reach their central nervous system targets or act as enzymes to deactivate opioid receptors, preventing the physiologic and psychoactive effects of the substance. A lack of "reward" for those suffering from SUD has been shown to result in cessation of use and promote long-term abstinence. Decreased antibody production costs and the advent of novel gene therapies that stimulate in vivo production of monoclonal antibodies have renewed interest in this strategy. Furthermore, advances in understanding of SUD immunopathogenesis have revealed distinct mechanisms of neuroimmune dysregulation underlying the disorder. Beyond assisting with cessation of drug use, antibody therapies could treat or reverse pathophysiologic hallmarks that contribute to addiction and which could be the cause of chronic cognitive defects resulting from drug use. In this review, we synthesize key current literature regarding the efficacy of immunotherapies in managing opioid addiction and SUD. We will explore the neuropharmacology underlying these treatments by relating evidence from studies on the use of antibody therapeutics to counteract various drug behaviors and by drawing parallels to the similar immunopathology observed in neurodegenerative disorders. Finally, we will discuss the implications of novel immunization technologies and the application of computational methods in developing personalized addiction treatments. SIGNIFICANCE STATEMENT: Significant new evidence contributing to our understanding of substance use disorders has recently emerged leading to a paradigm shift concerning the role of immunology in the neuropathogenesis of opioid use disorder. Concurrently, immunotherapeutic technologies such as antibody therapeutics have advanced the capabilities regarding applications that take advantage of these key principles. This article reviews key antibody-based treatments being studied and highlights directions for further research that may contribute to the management of opioid use disorder.

The development of opioid vaccines as a novel strategy for the treatment of opioid use disorder and overdose prevention

Opioid use disorder (OUD) affects over 40 million people worldwide, creating significant social and economic burdens. Medication for opioid use disorder (MOUD) is often considered the primary treatment approach for OUD. MOUD, including methadone, buprenorphine, and naltrexone, is effective for some, but its benefits may be limited by poor adherence to treatment recommendations. Immunopharmacotherapy offers an innovative approach by using vaccines to generate antibodies that neutralize opioids, blocking them from crossing the blood-brain barrier and reducing their psychoactive effects. To date, only 3 clinical trials for opioid vaccines have been published. While these studies demonstrated the potential of opioid vaccines for relapse prevention, there is currently no standardized protocol for evaluating their effectiveness. We have reviewed recent preclinical studies that demonstrated the efficacy of vaccines targeting opioids, including heroin, morphine, oxycodone, hydrocodone, and fentanyl. These studies showed that vaccines against opioids reduced drug reinforcement, decreased opioid-induced antinociception, and increased survival rates against lethal opioid doses. These studies also demonstrated the importance of vaccine formulation and the use of adjuvants in enhancing antibody production and specificity. Finally, we highlighted the strengths and concerns associated with the opioid vaccine treatment, including ethical considerations.

COT-TT vaccine attenuates cocaine-seeking and cocaine-conditioned place preference in rats

Vaccination active, promising alternative immunological strategy to treat of CUD. Various models of cocaine vaccines have been evaluated in animals and humans with relative success. In this sense, it is necessary to improve or optimize the cocaine vaccines already evaluated. Our laboratory previously reported the efficacy of the tetanus toxoid-conjugated morphine vaccine (M6-TT). The M6-TT vaccine can generate high titers of antibodies and reduce heroin-induced behavioral effects in rodents. So, it would be plausible to assume that if we modify the M6-TT vaccine by changing the hapten and maintaining the rest of the structural elements of the vaccine, we will maintain the properties of the M6-TT vaccine (high antibody titers). The objective of this study was to determine whether the antibodies generated by a tetanus toxoid-conjugated cocaine vaccine (COC-TT) can recognize and capture cocaine and decrease the cocaine-induced reinforcing effects. Male Wistar rats were immunized with the COC-TT. A solid-phase antibody-capture ELISA was used to monitor antibody titer responses after each booster dose in vaccinated animals. The study used cocaine self-administration and place-preference testing to evaluate the cocaine-reinforcing effects. The COC-TT vaccine could generate high levels of anti-cocaine antibodies. The antibodies reduced the cocaine self-administration and cocaine place preference. In addition, they decreased the cocaine-induced Fos protein expression. These findings suggest that the COC-TT vaccine generates a robust immunogenic response capable of reducing the reinforcing effects of cocaine, which supports its possible future use in clinical trials in patients with CUD.

Development of Clinically Viable Non-Muscle Myosin II Small Molecule Inhibitors with Broad Therapeutic Potential

Non-muscle myosin II (NMII), a molecular motor that regulates critical processes such as cytokinesis and neuronal synaptic plasticity, has substantial therapeutic potential. However, translating this potential to in vivo use has been hampered by the lack of selective tools. The most prototypical non-selective inhibitor, blebbistatin inactivates both NMII and cardiac myosin II (CMII), a key regulator of heart function. Using rational drug design, we developed a series of NMII inhibitors that improve tolerability by selectively targeting NMII over CMII, including MT-228, which has excellent properties such as high brain penetration and efficacy in preclinical models of stimulant use disorder, which has no current FDA-approved therapies. The structure of MT-228 bound to myosin II provides insight into its 17-fold selectivity for NMII over CMII. MT-228's broad therapeutic window opens the door to new disease treatments and provides valuable tools for the scientific community, along with promising leads for future medication development.

Highlights

Research suggests numerous indications, from axon regeneration and cancer, would benefit from a small molecule inhibitor of non-muscle myosin II, a molecular motor that regulates the actin cytoskeleton. Current chemical probe options are very limited and lack sufficient safety for in vivo studies, which we show is primarily due to potent inhibition of cardiac myosin II.Rational design that focused on improving target selectivity over the pan-myosin II inhibitor, blebbistatin, led to the identification of MT-228, a small molecule inhibitor with a wide therapeutic window.High-resolution structure of MT-228 bound to myosin II reveals that selectivity results from a different positioning compared to blebbistatin and an important sequence difference between cardiac and non-muscle myosin II in the inhibitor binding pocket.A single administration of MT-228 shows long-lasting efficacy in animal models of stimulant use disorder, a current unmet and rapidly escalating need with no FDA-approved treatments.

Application of microbial enzymes in medicine and industry: current status and future perspectives

Microbes are a major source of enzymes due to their ability to be mass-cultivated and genetically modified. Compared with plant and animal enzymes, microbial enzymes are more stable and active. Enzymes are generally classified into six classes based on their reaction, substrate specificity and mechanism of action. In addition to their application in medicine for treating diseases, these compounds are used as anti-inflammatory, thrombolytic and digestive agents. However, challenges such as immunogenicity, tissue specificity and short in vivo half-life make clinical trials complex. Enzymes are metabolic catalysts in industry and their production and extraction must be optimized to preserve profitability due to rising demand. The present review highlights the increasing importance of bacterial enzymes in industry and medicine and explores methods for their production, extraction and purification.

New medications development for smoking cessation

Diseases associated with nicotine dependence in the form of habitual tobacco use are a major cause of premature death in the United States. The majority of tobacco smokers will relapse within the first month of attempted abstinence. Smoking cessation agents increase the likelihood that smokers can achieve long-term abstinence. Nevertheless, currently available smoking cessation agents have limited utility and fail to prevent relapse in the majority of smokers. Pharmacotherapy is therefore an effective strategy to aid smoking cessation efforts but considerable risk of relapse persists even when the most efficacious medications currently available are used. The past decade has seen major breakthroughs in our understanding of the molecular, cellular, and systems-level actions of nicotine in the brain that contribute to the development and maintenance of habitual tobacco use. In parallel, large-scale human genetics studies have revealed allelic variants that influence vulnerability to tobacco use disorder. These advances have revealed targets for the development of novel smoking cessation agents. Here, we summarize current efforts to develop smoking cessation therapeutics and highlight opportunities for future efforts.

Chemical tools for the opioids

The opioids are potent and widely used pain management medicines despite also possessing severe liabilities that have fueled the opioid crisis. The pharmacological properties of the opioids primarily derive from agonism or antagonism of the opioid receptors, but additional effects may arise from specific compounds, opioid receptors, or independent targets. The study of the opioids, their receptors, and the development of remediation strategies has benefitted from derivatization of the opioids as chemical tools. While these studies have primarily focused on the opioids in the context of the opioid receptors, these chemical tools may also play a role in delineating mechanisms that are independent of the opioid receptors. In this review, we describe recent advances in the development and applications of opioid derivatives as chemical tools and highlight opportunities for the future.