Cancer-Related Neuropathic Pain: Review and Selective Topics

FTY720/Fingolimod mitigates paclitaxel-induced Sparcl1-driven neuropathic pain and breast cancer progression

Paclitaxel is among the most active chemotherapy drugs for the aggressive triple negative breast cancer (TNBC). Unfortunately, it often induces painful peripheral neuropathy (CIPN), a major debilitating side effect. Here we demonstrate that in naive and breast tumor-bearing immunocompetent mice, a clinically relevant dose of FTY720/Fingolimod that targets sphingosine-1-phosphate receptor 1 (S1PR1), alleviated paclitaxel-induced neuropathic pain. FTY720 also significantly attenuated paclitaxel-stimulated glial fibrillary acidic protein (GFAP), a marker for activated astrocytes, and expression of the astrocyte-secreted synaptogenic protein Sparcl1/Hevin, a key regulator of synapse formation. Notably, the formation of excitatory synapses containing VGluT2 in the spinal cord dorsal horn induced by paclitaxel was also inhibited by FTY720 treatment, supporting the involvement of astrocytes and Sparcl1 in CIPN. Furthermore, in this TNBC mouse model that mimics human breast cancer, FTY720 administration also enhanced the anti-tumor effects of paclitaxel, leading to reduced tumor progression and lung metastasis. Taken together, our findings suggest that targeting the S1P/S1PR1 axis with FTY720 is a multipronged approach that holds promise as a therapeutic strategy for alleviating both CIPN and enhancing the efficacy of chemotherapy in TNBC treatment.

Cancer history and physical function in patients with cardiovascular disease

Both cancer and cardiovascular disease (CVD) cause skeletal muscle mass loss, thereby increasing the likelihood of a poor prognosis. We investigated the association between cancer history and physical function and their combined association with prognosis in patients with CVD. We retrospectively reviewed 3,796 patients with CVD (median age: 70 years; interquartile range [IQR]: 61-77 years) who had undergone physical function tests (gait speed and 6-minute walk distance [6MWD]) at discharge. We performed multiple linear regression analyses to assess potential associations between cancer history and physical function. Moreover, Kaplan-Meier curves and Cox regression analyses were used to evaluate prognostic associations in four groups of patients categorized by the absence or presence of cancer history and of high or low physical function. Multiple regression analyses showed that cancer history was significantly and independently associated with a lower gait speed and 6MWD performance. A total of 610 deaths occurred during the follow-up period (median: 3.1 years; IQR: 1.4-5.4 years). The coexistence of low physical function and cancer history in patients with CVD was associated with a significantly higher mortality risk, even after adjusting for covariates (cancer history/low gait speed, hazard ratio [HR]: 1.93, P < 0.001; and cancer history/low 6MWD, HR: 1.61, P = 0.002). Cancer history is associated with low physical function in patients with CVD, and the combination of both factors is associated with a poor prognosis.

Advances in the Treatment of Neuropathic Pain by Sympathetic Regulation

PURPOSE OF REVIEW

To explore the mechanism and therapeutic effect of sympathetic nerve regulation on neuropathic pain.

RECENT FINDINGS

A comprehensive search was conducted in the PubMed and CNKI libraries, using the following keywords: stele ganglion block, neuropathic pain, sympathetic nerve block, sympathetic chemical destruction, and sympathetic radiofrequency thermocoagulation. We selected and critically reviewed research articles published in English that were related to sympathetic modulation in the treatment of neuropathic pain. The collected literature will be classified according to content and reviewed in combination with experimental results and clinical cases. Neuropathic pain was effectively treated with sympathetic regulation technology. Its mechanism includes the inhibition of sympathetic nerve activity, regulation of the inflammatory response, and inhibition of pain transmission, which greatly alleviates neuropathic pain in patients. Stellate ganglion blocks, thoracic and lumbar sympathectomies, chemical destruction, and radiofrequency thermocoagulation have been widely used to treat neuropathic pain. Sympathetic regulation can effectively relieve pain symptoms and improve the patient's quality of life by inhibiting sympathetic nerve activity, reducing the production and release of pain-related mediators, and inhibiting pain transmission. CT-guided radiofrequency thermocoagulation of the thoracic and lumbar sympathetic nerves is effective and durable, with few complications, and is recommended as a treatment for intractable neuropathic pain.

NT5DC2 knockdown suppresses progression, glycolysis, and neuropathic pain in triple-negative breast cancer by blocking the EGFR pathway

Triple-negative breast cancer (TNBC) is an exceptionally aggressive breast cancer subtype associated with neuropathic pain. This study explores the effects of 5'-nucleotidase domain-containing protein 2 (NT5DC2) on the progression of TNBC and neuropathic pain. Microarray analysis was conducted to identify differentially expressed genes in TNBC and the pathways involved. Gain- and loss-of-function assays of NT5DC2 were performed in TNBC cells, followed by detection of the extracellular acidification rate, adenosine triphosphate (ATP) levels, lactic acid production, glucose uptake, proliferation, migration, and invasion in TNBC cells. Macrophages were co-cultured with TNBC cells to examine the release of polarization-related factors and cytokines. A xenograft tumor model was established for in vivo validation. In addition, a mouse model of neuropathic pain was established through subepineural injection of TNBC cells, followed by measurement of the sciatic functional index and behavioral analysis to assess neuropathic pain. NT5DC2 was upregulated in TNBC and was positively correlated with epidermal growth factor receptor (EGFR). NT5DC2 interacted with EGFR to promote downstream signal transduction in TNBC cells. NT5DC2 knockdown diminished proliferation, migration, invasion, the extracellular acidification rate, ATP levels, lactic acid production, and glucose uptake in TNBC cells. Co-culture with NT5DC2-knockdown TNBC cells alleviated the M2 polarization of macrophages. Furthermore, NT5DC2 knockdown reduced tumor growth and neuropathic pain in mice. Importantly, activation of the EGFR pathway counteracted the effects of NT5DC2 knockdown. NT5DC2 knockdown protected against TNBC progression and neuropathic pain by inactivating the EGFR pathway.

The Edmonton Classification System for Cancer Pain in Patients with Bone Metastasis: a descriptive cohort study

PURPOSE

We describe the prevalence of the Edmonton Classification System for Cancer Pain (ECS-CP) features in patients with bone metastasis and cancer-induced bone pain (CIBP) and the relationship between ECS-CP features, pain intensity, and opioid consumption.

METHODS

We assessed ECS-CP features and recoded pain mechanisms and opioid use in adult patients with bone metastasis. Validated measures were used to assess pain intensity, incident pain, psychological distress, addictive behavior, and cognition.

RESULTS

Among 147 eligible patients, 95.2% completed the assessment. Mean participant age was 73.2 years, the majority female (52.1%) with breast cancer occurring most commonly (25.7%). One or more ECS-CP features were present in 96.4% and CIBP in 75.7% of patients. The median average and worst pain scores were 3 and 6, respectively. Neuropathic pain was the most prevalent pain mechanism (45.0%) and was associated with breakthrough pain frequency (p=0.014). Three-quarters had incident pain, which was strongly associated with a higher average and worst pain scores (3.5 and 7, p<0.001 for both), background oral morphine equivalent daily dose (26.7mg, p=0.005), and frequency of daily breakthrough analgesia (1.7 doses/day, p=0.007). Psychological distress (n=90, 64.3%) was associated with a significantly higher average pain score (4, p=0.009) and a slightly higher worst pain score (7, p=0.054). Addictive behaviour and cognitive dysfunction were relatively uncommon (18.6% and 12.9%, respectively).

CONCLUSION

There is a need to promote standardized assessment and classification of pain syndromes such as CIBP. The ECS-CP may allow us to consider CIBP in a systematic manner and develop personalized pain interventions appropriate to the pain profile.

TRIAL REGISTRATION

Retrospectively registered in ANZCTR ACTRN12622000853741 (16/06/2022).

Methadone rotation versus other opioid rotation for refractory cancer induced bone pain: protocol of an exploratory randomised controlled open-label study

BACKGROUND

A third of patients with advanced cancer and bone metastasis suffer from cancer induced bone pain (CIBP), impeding quality of life, psychological distress, depression and anxiety. This study will evaluate the impact of an opioid rotation, comparing methadone rotation with other opioid rotation in patients with refractory CIBP.

METHODS

This open-label randomised controlled trial will recruit cancer patients with CIBP and inadequate pain control despite established baseline opioid and/or intolerable opioid side effects from cancer and palliative care services. Participants will be at least 18 years old, with a predicted prognosis of greater than 8 weeks, meet the core diagnostic criteria for CIBP, have a worst pain score of ≥ 4 of 10 from CIBP and/ or have opioid toxicity (graded ≥ 2 on Common Terminology Criteria for Adverse Events). Participants will have sufficiently proficient English to complete questionnaires and provide informed consent. Participants will be randomised 1:1 to be rotated to methadone to another opioid. The primary objective is to examine the impact of opioid rotation in improving CIBP by comparing analgesic efficacy, safety and tolerability in the two arms. Secondary objectives will assess changes in the intensity, duration and frequency of breakthrough pain, requirement of breakthrough analgesia, overall opioid escalation index, and time taken to observe improvement in pain reduction, pain interference and quality of life.

DISCUSSION

Laboratory studies suggest the involvement of neuropathic involvement in the mechanism of CIBP, though there remains no clear evidence of the routine use of neuropathic agents. Methadone as an analgesic agent may have a role to play in this cohort of patients, thus warranting further exploratory studies.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry No: ACTRN12621000141842. Registered 11 February 2021.

Worldwide Productivity and Research Trend of Publications Concerning Cancer-Related Neuropathic Pain: A Bibliometric Study

Cancer-related neuropathic pain is a common adverse effect in the process of cancer development and treatment and has gradually attracted the attention of researchers. The purpose of this article is to systematically review the articles on cancer-related neuropathic pain published between 2012 and 2021 and visualize the data through CiteSpace and R software. The results show that in the past 10 years, a total of 5715 articles have been published, involving 118 categories, of which the most is Clinical Neurology, followed by Neurosciences, Pharmacology Pharmacy. The country with the most published articles is the United States, followed by China and Italy. A total of 22,228 authors were involved in the study of cancer-related neuropathic pain. These historical opinions about cancer-related neuropathic pain could be an important practical basis for further research into potential development trends.

Cellular and Molecular Machinery of Neuropathic Pain: an Emerging Insight

Purpose of Review

Neuropathic pain (NP) has been ubiquitously characterized by lesion and its linked somatosensory system either the central nervous system (CNS) or peripheral nervous system (PNS) This PNS episode is the most prevalent site of NP origin and is found to be associated with afferent nerve fibers carrying pain signals from injured/trauma site to the CNS including the brain. Several kinds of pharmacotherapeutic drugs shuch as analgesics, anti-convulsants, and anti-depressants are being employed for the its possible interventions. The NP has been a great interest to follow different pathophysiological mechanisms which are often considered to correlate with the metabolic pathways and its mediated disease. There is paucity of knowledge to make such mechanism via NP.

Recent Finding

Most notably, recent pandemic outbreak of COVID-19 has also been reported in chronic pain mediated diabetes, inflammatory disorders, and cancers. There is an increasing incidence of NP and its complex mechanism has now led to identify the possible investigations of responsible genes and proteins via bioinformatics tools. The analysis might be more instrumental as collecting the genes from pain genetic database, analyzing the variants through differential gene expression (DEG) and constructing the protein–protein interaction (PPI) networks and thereby determining their upregulating and downregulating pathways.

Summary

This review sheds a bright light towards several mechanisms at both cellular and molecular level, correlation of NP-mediated disease mechanism and possible cell surface biomarkers (receptors), and identified genes could be more promising for their pharmacological targets.

Treatment of Neuropathic Pain Directly Due to Cancer: An Update

Simple Summary

This review discusses treatment approaches for providing pain relief to oncological patients affected by pain caused by nerve damage due to the tumor, also known as neuropathic cancer pain. Although being encountered often and causing a relevant burden to these patients, neuropathic cancer pain remains still difficult to diagnose and treat. Strong evidence about the best drugs to be used remain limited, as do therapeutic choices.

Abstract

Neuropathic pain can be defined as pain related to abnormal somatosensory processing in either the peripheral or central nervous system. In this review article, with neuropathic cancer pain (NCP), we refer to pain due to nervous tissue lesions caused by the tumor or its metastases. Nervous tissue damage is the cause of cancer pain in approximately 40% of those experiencing cancer pain. Recognizing a neuropathic pathophysiology in these cases may be difficult and requires specific criteria that are not homogenously applied in clinical practice. The management of this type of pain can be challenging, requiring the use of specific non-opioid adjuvant drugs. The majority of the criteria for NCP diagnosis and management have been based mainly on results from the noncancer population, risking the failure of addressing the specific needs of this population of patients. In this review, we summarize current management options available for NCP and provide some insights on new promising treatments.

Spinal Cord Stimulation to Treat Unresponsive Cancer Pain: A Possible Solution in Palliative Oncological Therapy

(1) Background: Treatment of cancer-related pain is still challenging, and it can be managed by both medical and interventional therapies. Spinal Cord Stimulation (SCS) is a minimally invasive technique, and its use is rapidly increasing in the treatment of chronic pain. (2) Materials and Methods: Our study aims to perform a review of the pertinent literature about current evidences in cancer pain treatment by Spinal Cord Stimulation. Moreover, we created a database based on case reports or case series (18 studies) in the literature. We analyzed a clinical group of oncological patients affected by intractable pain undergoing SCS implantation, focusing on outcome. (3) Results: The analysis of the 18 included studies in our series has shown a reduction in painful symptoms in 48 out of 56 treated patients (87.51%); also 53 out of 56 patients (96.64%) have shown an improvement in their Quality of Life (QoL). (4) Conclusions: Spinal Cord Stimulation can be considered an efficient method in the treatment of cancer-related pain. However, literature regarding SCS for the treatment of cancer-related pain is largely represented by case reports and small case series, with no effective population studies or Randomized Controlled Trials demonstrating the efficacy and the level of evidence. Further prospective studies are needed.

GABAB Receptors and Pain

A substantial fraction of the human population suffers from chronic pain states, which often cannot be sufficiently treated with existing drugs. This calls for alternative targets and strategies for the development of novel analgesics. There is substantial evidence that the G protein-coupled GABA_B receptor is involved in the processing of pain signals and thus has long been considered a valuable target for the generation of analgesics to treat chronic pain. In this review, the contribution of GABA_B receptors to the generation and modulation of pain signals, their involvement in chronic pain states as well as their target suitability for the development of novel analgesics is discussed.

Downregulating lncRNA PVT1 Relieves Astrocyte Overactivation Induced Neuropathic Pain Through Targeting miR-186-5p/CXCL13/CXCR5 Axis

Spinal cord injury (SCI) is one of the main causes leading to neuropathic pain. Here, we aim to explore the molecular mechanism and function of lncRNA PVT1 in neuropathic pain induced by SCI. The expression of lncRNA PVT1, microRNA (miR) - 186-5p was measured via quantitative reverse transcription PCR (qRT-PCR), and the activation of astrocytes (labeled by GFAP) was detected by immunohistochemistry. Western blot was conducted to detect the expression of chemokine ligand 13 (CXCL13), chemokine receptor 5 (CXCR5), cyclooxygenase-2 (COX2), inducible nitric oxide synthase (iNOS) and glial fibrillary acidic protein (GFAP) in spinal cord injury lesions. The levels of inflammatory cytokines (including IL-1β and IL-6) and MDA in tissues were examined via Enzyme-linked immunosorbent assay (ELISA). In vitro experiments were also conducted in primary cultured astrocyte to explore the response of astrocyte to lipopolysaccharide (LPS). What's more, the PVT1-miR-186-5p interaction was verified via the dual luciferase activity assay and RNA immunoprecipitation (RIP) assay. The results demonstrated that the levels of PVT1, CXCL13 and CXCR5 were upregulated, while miR-186-5p were decreased in SCI rats' spinal cord and LPS-mediated astrocytes. In the SCI model, PVT1 depletion significantly alleviated neuropathic pain, astrocytic activation and reduced the expression of neuroinflammatory factors and proteins. The relevant mechanism studies confirmed that PVT1 is a competitive endogenous RNA (ceRNA) of miR-186-5p, targets and inhibits its expression and promotes the expression of CXCL13/CXCR5, while miR-186-5p targets CXCL13. In conclusion, inhibition of lncRNA PVT1 alleviates neuropathic pain in SCI rats by upregulating miR-186-5p and down-regulating CXCL13/CXCR5. The PVT1/miR-186-5p/CXCL13/CXCR5 axis can be used as a new therapeutic target for neuropathic pain.

Not All Pain is Created Equal: Basic Definitions and Diagnostic Work-Up

Chronic pain is considered a public health priority by the World Health Organization and European health institutions. It has reached alarming proportions in terms of disability, consumption of health and social resources, and impact on primary and specialist care services. Primary care physicians are often called on to manage this condition. Chronic pain management can be challenging due to its complexity. It has traditionally been considered to include nociceptive pain that that persists longer than the normal healing time, neuropathic pain lasting more than 3 months, or a combination of these. More recently, a third descriptor, nociplastic (primary) pain, was added to classify patients with chronic pain conditions such as fibromyalgia, nonspecific back pain, or mixed pain that persists or other conditions in which altered central pain modulation results in central sensitization and chronic pain in the absence of actual or threatened damage to tissues, including in the somatosensory nervous system. This document provides an overview of pain types and their underlying mechanisms. Successful pain management is facilitated by identification of the pain type. A set of diagnostic tools and a pain algorithm are presented to guide the clinician toward the correct diagnosis. The algorithm identifies cases that may require referral to a pain specialist. Once the site of origin of the pain (the "pain generator") is identified, or a primary pain syndrome is suspected, the accompanying article provides information and rationale to support treatment decisions based on patient characteristics.

Spinal cord stimulation alleviates intractable pain due to malignant pleural mesothelioma: a case report

Background

Patients with malignant pleural mesothelioma (MPM) frequently complain of intractable pain that is resistant to conservative treatments. Although spinal cord stimulation (SCS) may be promising in the alleviation of such devastating pain, the effects of SCS on MPM-associated pain and the appropriate timing of its application remain unknown.

Case presentation

A 66-year-old man diagnosed with MPM presented with severe neuropathic pain due to rapid progression of the tumor to the intercostal nerves. The patient immediately decided to receive SCS implantation and burst stimulus, which relieved the conservative therapy-resistant pain and improved his sleep and daily activities.

Conclusion

This report suggests that the execution of SCS as soon as possible may help to alleviate MPM symptoms. Since MPM extends aggressively to the thorax and nerves that cause mixed nociceptive and/or neuropathic pain, appropriate pain management requires the proper assessment of the etiology by an expert in pain management.

The use of antineuropathic medications for the treatment of chronic pain

Chronic pain syndromes cost the US healthcare system over $600 billion per year. A subtype of chronic pain is neuropathic pain (NP), which is defined as "pain caused by a lesion or disease of the somatosensory system," according to the International Association for the Study of Pain (IASP). The pathophysiology of neuropathic pain is very complex, and more research needs to be done to find the exact mechanism. Patients that have preexisting conditions such as cancer and diabetes are at high-risk of developing NP. Many NP patients are misdiagnosed and receive delayed treatment due to a lack of a standardized classification system that allows clinicians to identify, understand, and utilize pain management in these patients. Medications like tricyclic antidepressants, serotonin-norepinephrine reuptake Inhibitor (SNRIs), and gabapentinoids are first-line treatments followed by opioids, cannabinoids, and other drugs. There are limited studies on the treatment of NP.

Perspectives on cannabis as a substitute for opioid analgesics

With the opioid epidemic reaching new heights in the USA, it has become critical to find suitable alternatives to opioids. Cannabis, an antinociceptive, is a strong contender to help patients reduce their opioid usage. A growing literature has been examining the complex effects cannabis has on pain relief and on opioid usage; whether it is a substitute for opioids or increases their use. This review explores the studies that compare cannabis-opioid interactions and presents some challenges of cannabis research and usage. The practical clinical pharmacology of cannabis as an analgesic, including the route of administration, safety and pharmacokinetics, are discussed to address the concerns, as well as possible solutions, of cannabis as a pain reliever.

Potential for endocannabinoid system modulation in ocular pain and inflammation: filling the gaps in current pharmacological options

Challenges in the management of ocular pain are an underappreciated topic. Currently available therapeutics lack both efficacy and clear guidelines for their use, with many also possessing unacceptable side effects. Promising novel agents would offer analgesic, anti-inflammatory, and possibly neuroprotective actions; have favorable ocular safety profiles; and show potential in managing neuropathic pain. Growing evidence supports a link between the endocannabinoid system (ECS) and a range of physiological and disease processes, notably those involving inflammation and pain. Both preclinical and clinical data suggest analgesic and anti-inflammatory actions of cannabinoids and ECS-modifying drugs in chronic pain conditions, including those of neuropathic origin. This review will examine existing evidence for the anatomical and physiological basis of ocular pain, specifically, ocular surface disease and the development of chronic ocular pain. The mechanism of action, efficacy, and limitations of currently available treatments will be discussed, and current knowledge related to ECS-modulation of ocular pain and inflammatory disease will be summarized. A perspective will be provided on the future directions of ECS research in terms of developing cannabinoid therapeutics for ocular pain.