Towards precision medicine for pain: diagnostic biomarkers and repurposed drugs

Pain in neuropsychiatry: Insights from animal models

Pain is the most common symptom reported in clinical practice, meaning that it is associated with many pathologies as either the origin or a consequence of other illnesses. Furthermore, pain is a complex emotional and sensorial experience, as the correspondence between pain and body damage varies considerably. While these issues are widely acknowledged in clinical pain research, until recently they have not been extensively considered when exploring animal models, important tools for understanding pain pathophysiology. Interestingly, chronic pain is currently considered a risk factor to suffer psychiatric disorders, mainly stress-related disorders like anxiety and depression. Conversely, pain appears to be altered in many psychiatric disorders, such as depression, anxiety and schizophrenia. Thus, pain and psychiatric disorders have been linked in epidemiological and clinical terms, although the neurobiological mechanisms involved in this pathological bidirectional relationship remain unclear. Here we review the evidence obtained from animal models about the co-morbidity of pain and psychiatric disorders, placing special emphasis on the different dimensions of pain.

Pain Detection with Bioimpedance Methodology from 3-Dimensional Exploration of Nociception in a Postoperative Observational Trial

Although the measurement of dielectric properties of the skin is a long-known tool for assessing the changes caused by nociception, the frequency modulated response has not been considered yet. However, for a rigorous characterization of the biological tissue during noxious stimulation, the bioimpedance needs to be analyzed over time as well as over frequency. The 3-dimensional analysis of nociception, including bioimpedance, time, and frequency changes, is provided by ANSPEC-PRO device. The objective of this observational trial is the validation of the new pain monitor, named as ANSPEC-PRO. After ethics committee approval and informed consent, 26 patients were monitored during the postoperative recovery period: 13 patients with the in-house developed prototype ANSPEC-PRO and 13 with the commercial device MEDSTORM. At every 7 min, the pain intensity was measured using the index of Anspec-pro or Medstorm and the 0-10 numeric rating scale (NRS), pre-surgery for 14 min and post-anesthesia for 140 min. Non-significant differences were reported for specificity-sensitivity analysis between ANSPEC-PRO (AUC = 0.49) and MEDSTORM (AUC = 0.52) measured indexes. A statistically significant positive linear relationship was observed between Anspec-pro index and NRS (r2 = 0.15, p < 0.01). Hence, we have obtained a validation of the prototype Anspec-pro which performs equally well as the commercial device under similar conditions.

Identification of MOR-Positive B Cell as Possible Innovative Biomarker (Mu Lympho-Marker) for Chronic Pain Diagnosis in Patients with Fibromyalgia and Osteoarthritis Diseases

Fibromyalgia (FM) diagnosis follows the American College of Rheumatology (ACR) criteria, based on clinical evaluation and written questionnaires without any objective diagnostic tool. The lack of specific biomarkers is a tragic aspect for FM and chronic pain diseases in general. Interestingly, the endogenous opioid system is close to the immune one because of the expression of opioid receptors on lymphocytes membrane. Here we analyzed the role of the Mu opioid receptor on B lymphocytes as a specific biomarker for FM and osteoarthritis (OA) patients. We enrolled three groups of females: FM patients, OA patients (chronic pain control group) and healthy subjects (pain-free negative control group). We collected blood samples to apply immunophenotyping analysis. Written tests were administrated for psychological analysis. Data were statistically analyzed. Final results showed that the percentage of Mu-positive B cells were statistically lower in FM and OA patients than in pain-free subjects. A low expression of Mu-positive B cell was not associated with the psychological characteristics investigated. In conclusion, here we propose the percentage of Mu-positive B cells as a biological marker for an objective diagnosis of chronic pain suffering patients, also contributing to the legitimacy of FM as a truly painful disease.

Applying Serum Cytokine Levels to Predict Pain Severity in Cancer Patients

Background and Aim

Cancers originating in the breast, lung and prostate often metastasize to the bone, frequently resulting in cancer-induced bone pain that can be challenging to manage despite conventional analgesic therapy. This exploratory study’s aim was to identify potential biomarkers associated with cancer-induced pain by examining a sample population of breast cancer patients undergoing bisphosphonate therapy.

Methods

A secondary analysis of the primary study was performed to quantify serum cytokine levels for correlation to pain scores. Cytokines with statistically significant correlations were then input into a stepwise regression analysis to generate a predictive equation for a patient’s pain severity. In an effort to find additional potential biomarkers, correlation analysis was performed between these factors and a more comprehensive panel of cytokines and chemokines from breast, lung, and prostate cancer patients.

Results

Statistical analysis identified nine cytokines (GM-CSF, IFNγ, IL-1β, IL-2, IL-4, IL-5, IL-12p70, IL-17A, and IL-23) that had significant negative correlations with pain scores and they could best predict pain severity through a predictive equation generated for this specific evaluation. After performing a correlation analysis between these factors and a larger panel of cytokines and chemokines, samples from breast, lung and prostate patients showed distinct correlation profiles, highlighting the clinical challenge of applying pain-associated cytokines related to more defined nociceptive states, such as arthritis, to a cancer pain state.

Conclusion

Exploratory analyses such as the ones presented here will be a beneficial tool to expand insights into potential cancer-specific nociceptive mechanisms and to develop novel therapeutics.

Best Practices in the Management of Nonmedical Opioid Use in Patients with Cancer-Related Pain

INTRODUCTION

Nonmedical opioid use (NMOU) in patients with cancer is a term covering a spectrum of nonprescribed opioid use. The extent to which an individual uses opioids in a nonprescribed manner will influence propensity for adverse effects such as neurotoxicity, substance use disorder, overdose, and death.

OBJECTIVES

The objectives of this study were to (A) evaluate current literature regarding management of NMOU in patients with cancer-related pain; (B) provide best practice recommendations based on evidence; and (C) integrate practices derived from the management of noncancer pain, where clinically appropriate or when the oncology literature is limited.

METHODS

This study is a narrative review.

IMPLICATIONS

Although harm from NMOU was thought to be rare among oncology patients, about one in five patients with cancer is at risk of adverse outcomes including prolonged opioid use, high opioid doses, and increased health care utilization. The management of NMOU can be challenging because pain is a multidimensional experience encompassing physical, psychological, and spiritual domains. An interdisciplinary team approach is most effective, and management strategies may include (A) education of patients and families; (B) harm reduction, including opioid switching, decreasing the overall daily dose, avoiding concurrent sedative use, and using adjuvant medications for their opioid-sparing potential; (C) managing psychological and spiritual distress with an interdisciplinary team and techniques such as brief motivational interviewing; and (D) risk mitigation by pill counts, frequent clinic visits, and accessing statewide prescription drug monitoring plans.

CONCLUSION

Although many of the management strategies for NMOU in patients with cancer-related pain are modeled on those for chronic non-cancer-related pain, there is emerging evidence that education and harm-reduction initiatives specifically for cancer-related pain are effective.

IMPLICATIONS FOR PRACTICE

Nonmedical opioid use (NMOU) in patients with cancer is a term covering a broad spectrum of nonprescribed opioid use. The extent to which an individual uses opioids in a nonprescribed manner will influence propensity for adverse effects such as neurotoxicity, substance use disorder, overdose, and death. This review evaluates the evidence for best practices in oncology and addresses limitations in the literature with supplemental evidence from noncancer chronic pain. Management recommendations for NMOU are provided, based on a combination of literature-based evidence and best clinical practice. Effective management of NMOU in oncology has the potential to improve quality of life, decrease health utilization, and improve survival.

Identification of novel analgesics through a drug repurposing strategy

The identification of new indications for approved or failed drugs is a process called drug repositioning or drug repurposing. The motivation includes overcoming the productivity gap that exists in drug development, which is a high-cost–high-risk process. Repositioning also includes rescuing drugs that have safely entered the market but have failed to demonstrate sufficient efficiency for the initial clinical indication. Considering the high prevalence of chronic pain, the lack of sufficient efficacy and the safety issues of current analgesics, repositioning seems to be an attractive approach. This review presents example of drugs that already have been repositioned and highlights new technologies that are available for the identification of additional compounds to stimulate the curiosity of readers for further exploration.