Inner Workings: Using vaccines to harness the immune system and fight drugs of abuse

Need for strategic communications and stakeholder engagement to advance acceptability of an overdose preventing vaccine targeting fentanyl

BACKGROUND

Fentanyl is a synthetic opioid, exposure to which has led to hundreds of thousands of overdose deaths. Novel vaccines are being developed that might protect against fentanyl overdose. Proactive attention to strategic communications and stakeholder engagement may smooth uptake of a novel vaccine given known challenges around vaccine hesitancy and concern for stigma related to substance use.

METHODS

Qualitative interviews (N = 74) with a purposive sample of adolescents/young adults with opioid use disorder (OUD), family members of persons with OUD, experts in substance use treatment and harm reduction, and community members were conducted and thematically analyzed to discern attitudes toward a fentanyl vaccine, and directions for communications and engagement.

RESULTS

Major themes reflected personal concerns for biomedical risk and system-level concerns for alignment and integration of an overdose preventing vaccine with prevailing beliefs about addiction and associated frameworks and philosophies for treatment and response.

CONCLUSION

Acceptability and implementation of a novel fentanyl vaccine targeting overdose will need precision communications that address biomedical, moral/spiritual, and structural perspectives about the nature of addiction. Education about the purpose and limits of a fentanyl vaccine, partnerships with diverse stakeholders from throughout the opioid response ecosystem and interweaving of a vaccine strategy into comprehensive prevention and treatment are recommended.

From hit to vial: Precision discovery and development of an imidazopyrimidine TLR7/8 agonist adjuvant formulation

Vaccination can help prevent infection and can also be used to treat cancer, allergy, and potentially even drug overdose. Adjuvants enhance vaccine responses, but currently, the path to their advancement and development is incremental. We used a phenotypic small-molecule screen using THP-1 cells to identify nuclear factor-κB (NF-κB)-activating molecules followed by counterscreening lead target libraries with a quantitative tumor necrosis factor immunoassay using primary human peripheral blood mononuclear cells. Screening on primary cells identified an imidazopyrimidine, dubbed PVP-037. Moreover, while PVP-037 did not overtly activate THP-1 cells, it demonstrated broad innate immune activation, including NF-κB and cytokine induction from primary human leukocytes in vitro as well as enhancement of influenza and SARS-CoV-2 antigen-specific humoral responses in mice. Several de novo synthesis structural enhancements iteratively improved PVP-037's in vitro efficacy, potency, species-specific activity, and in vivo adjuvanticity. Overall, we identified imidazopyrimidine Toll-like receptor-7/8 adjuvants that act in synergy with oil-in-water emulsion to enhance immune responses.

Opioid vaccine clinical testing: lessons learned

PURPOSE OF REVIEW

Opioid use disorder (OUD) presents a serious public health concern, with dramatic increases in opioid-overdose mortality in recent years and a small percentage of those with OUD accessing or remaining engaged with available treatments. Efforts are currently underway to identify vaccines targeting opioids, which could provide a novel and complimentary approach. The current review provides an overview of existing literature, practical considerations for designing and conducting clinical trials with vaccines for opioids, and future directions.

RECENT FINDINGS

This review covers the following themes: clinical trial design and selection of endpoints, timepoint selection, practical considerations and lessons learned from the first (ongoing) trial of a vaccine targeting opioids, and future directions.

SUMMARY

Efforts to develop and test vaccines targeting OUD are based on a foundation of preclinical work and close collaboration between preclinical and clinical researchers. Efforts to learn from shortcomings of prior clinical trials of vaccines for other substances are essential in designing and testing effective vaccines for OUD. Design and implementation of clinical trials for a vaccine for OUD requires careful balance of participant safety and strategies for retention and efforts to gather viable data to inform future work.

Immunotherapeutic strategies for treating opioid use disorder and overdose

INTRODUCTION

Development and implementation of effective treatments for opioid use disorder (OUD) and prevention of overdose are urgent public health needs. Though existing medications for OUD (MOUD) are effective, barriers to initiation and retention in treatment persist. Therefore, development of novel treatments, especially those may complement existing treatments, is needed.

AREAS COVERED

This review provides an overview of vaccines for substance use disorders (SUD) and mechanisms underlying their function and efficacy. Next, we focus on existing preclinical and clinical trials of SUD vaccines. We focus briefly on related strategies before providing an expert opinion on prior, current, and future work on vaccines for OUD. We included published findings from preclinical and clinical trials found on PubMed and ScienceDirect as well as ongoing or initiated trials listed on ClinicalTrials.gov.

EXPERT OPINION

The present opioid overdose and OUD crises necessitate urgent development and implementation of effective treatments, especially those that offer protection from overdose and can serve as adjuvants to existing medications. Promising preclinical trial results paired with careful efforts to develop vaccines that account for prior SUD vaccine shortcomings offer hope for current and future clinical trials of opioid vaccines. Clinical advantages of opioid vaccines appear to outnumber disadvantages, which may result in improved treatment options.

A Rapid Method for Direct Quantification of Antibody Binding-Site Concentration in Serum

The quantitation of the available antibody binding-site concentration of polyclonal antibodies in serum is critical in defining the efficacy of vaccines against substances of abuse. We have conceptualized an equilibrium dialysis (ED)-based approach coupled with fluorimetry (ED-fluorimetry) to measure the antibody binding-site concentration to the ligand in an aqueous environment. The measured binding-site concentrations in monoclonal antibody (mAb) and sera samples from TT-6-AmHap-immunized rats by ED-fluorimetry are in agreement with those determined by a more established equilibrium dialysis coupled with ultraperformance liquid chromatography tandem mass spectrometry (ED-UPLC-MS/MS). Importantly, we have shown that the measured antibody binding-site concentrations to the ligand by ED-fluorimetry were not influenced by the sample serum matrix; thus, this method is valid for determining the binding-site concentration of polyclonal antibodies in sera samples. Further, we have demonstrated that under appropriate analytical conditions, this method resolved the total binding-site concentrations on a nanomolar scale with good accuracy and repeatability within the microliter sample volumes. This simple, rapid, and sample preparation-free approach has the potential to reliably perform quantitative antibody binding-site screening in serum and other more complex biological fluids.

Vaccines against Drug Abuse-Are We There Yet?

BACKGROUND

Drug abuse is a worldwide problem that is detrimental to public health. The potential for drug abuse extends to both legal and illicit drugs. Drawbacks associated with current treatments include limited effectiveness, potential side effects and, in some instances, the absence of or concerns with approved therapy options. A significant amount of clinical research has been conducted investigating immunotherapy as a treatment option against drug abuse. Vaccines against drug abuse have been the main area of research, and are the focus of this review.

METHODS

An extensive search using "EBSCOhost (Multiple database collection)" with all 28 databases enabled (including "Academic Search Ultimate", "CINAHL Plus with Full Text", and MEDLINE), interrogation of the ClinicalTrials.gov website, and searches of individual clinical trial registration numbers, was performed in February and March of 2022. This search extended to references within the obtained articles.

RESULTS

A total of 23 registered clinical trials for treating drug abuse were identified: 15 for treatment of nicotine abuse (all vaccine-based trials), 6 against cocaine abuse (4 were vaccine-based trials and 2 were metabolic-enzyme-based trials), 1 against methamphetamine abuse (a monoclonal-antibody-based trial), and 1 multivalent opioid treatment (vaccine-based trial). As indicated on the ClinicalTrials.gov website (Home-ClinicalTrials.gov), the status of all but two of these trials was "Completed". Phase 3 clinical trials were completed for vaccine treatments against nicotine and cocaine abuse only.

CONCLUSION

Evidence in the form of efficacy data indicates that vaccines are not an option for treating nicotine or cocaine abuse. Efficacy data are yet to be obtained through completion of clinical trials for vaccines against opioid abuse. These findings align with the absence of regulatory approval for any of these treatments. This review further highlights the need for novel treatment strategies in instances where patients do not respond to current treatments, and while the search for efficacious vaccine-based treatments continues.