Monoclonal antibodies for chronic pain: a practical review of mechanisms and clinical applications

Recent Advances in Management of Neuropathic, Nociceptive, and Chronic Pain: A Narrative Review with Focus on Nanomedicine, Gene Therapy, Stem Cell Therapy, and Newer Therapeutic Options

PURPOSE OF REVIEW

This manuscript summarizes novel clinical and interventional approaches in the management of chronic, nociceptive, and neuropathic pain.

RECENT FINDINGS

Pain can be defined as a feeling of physical or emotional distress caused by an external stimulus. Pain can be grouped into distinct types according to characteristics including neuropathic pain, which is a pain caused by disease or lesion in the sensory nervous system; nociceptive pain, which is pain that can be sharp, aching, or throbbing and is caused by injury to bodily tissues; and chronic pain, which is long lasting or persisting beyond 6 months. With improved understanding of different signaling systems for pain in recent years, there has been an upscale of methods of analgesia to counteract these pathological processes. Novel treatment methods such as use of cannabinoids, stem cells, gene therapy, nanoparticles, monoclonal antibodies, and platelet-rich plasma have played a significant role in improved strategies for therapeutic interventions. Although many management options appear to be promising, extensive additional clinical research is warranted to determine best practice strategies in the future for clinicians.

Exploring causal correlations between inflammatory cytokines and ankylosing spondylitis: a bidirectional mendelian-randomization study

Background

The impact of inflammatory factors on the development of Ankylosing Spondylitis (AS) is widely recognized, but the exact causal relationship remains unclear.

Methods

The bidirectional mendelian-randomization study utilized genetic data from a genome-wide association study (GWAS) of 186 AS cases and 456,162 controls of European ancestry. Inflammatory cytokines were obtained from a GWAS summary of 8,293 healthy participants. Causal associations were primarily investigated using the inverse variance-weighted method, supplemented by MR Egger, weighted median and weighted mode analyses. Heterogeneity in the results was assessed using the Cochrane Q test. Horizontal pleiotropy was evaluated through the MR-Egger intercept test and the MR pleiotropy residual sum and outliers (MR-PRESSO) test. Sensitivity analysis was conducted through leave-one-out analysis.

Results

The results suggest a genetically predicted potential association between beta-nerve growth factor (βNGF), Interleukin-1-beta (IL-1β), and TNF-related apoptosis inducing ligand (TRAIL) with the risk of AS (OR: 2.17, 95% CI: 1.13-4.16; OR: 0.41, 95% CI: 0.18-0.95,; OR: 1.47, 95% CI: 1.02-2.13).Additionally, Interleukin-12p70 (IL-12p70), Interleukin-17 (IL-17), Interleukin-6 (IL-6), Interleukin-4 (IL-4), Stromal-cell-derived factor 1 alpha (SDF-1α), Macrophage inflammatory protein 1β (MIP1β), Monocyte chemoattractant protein-3 (MCP-3), Platelet-derived growth factor bb (PDGFbb), Granulocyte-colony stimulating factor (GCSF), Fibroblast growth factor basic (bFGF), TNF-related apoptosis inducing ligand (TRAIL), and Interferon-gamma (IFN -γ) are suggested as consequences of AS in genetically prediction.No evidence of horizontal pleiotropy or heterogeneity between the genetic variants was found (P>0.05), and a leave-one-out test confirmed the stability and robustness of this association.

Conclusion

These findings suggest that βNGF, IL-1β, and TRAIL may play a crucial role in the pathogenesis of AS. Additionally, AS may impact the expression of cytokines such as IL-12p70, IL-17, IL-6, IL-4, SDF-1α, MIP1β, MCP-3, PDGFbb,GCSF, bFGF,TRAIL,and IFN-γ. Further investigations are warranted to determine whether these biomarkers can be utilized for the prevention or treatment of AS.

Targeting dorsal root ganglia and primary sensory neurons for the treatment of chronic pain: an update

INTRODUCTION

Current treatments for chronic pain are inadequate. Here, we provide an update on the new therapeutic strategies that target dorsal root ganglia (DRGs) in the peripheral nervous system for a better and safer treatment of chronic pain.

AREAS COVERED

Despite the complex nature of chronic pain and its underlying mechanisms, we do know that changes in the plasticity and modality of neurons in DRGs play a pivotal role. DRG neurons are heterogenous and offer potential pain targets for different therapeutic interventions. We discuss the last advancements of these interventions, which include the use of systemic and local administrations, selective nerve drug delivery, and gene therapy. In particular, we provide updates and further details on the molecular characterization of primary sensory neurons, new analgesics entering the market, and future gene therapy approaches.

EXPERT OPINION

DRGs and primary sensory neurons are promising targets for chronic pain treatment due to their key role in pain signaling, unique anatomical location, and the potential for different targeted therapeutic interventions.

Migraine Treatment Using Erenumab: Can Lead to a Cognitive and Psychological Qualitative Improvement?

Migraine is one of the most disabling disorders in the world, associated with poor quality of life. Migraine prevention strategies have increasingly evolved since monoclonal antibodies against the calcitonin gene-related peptide (CGRP), or its receptor, were identified. CGRP is the ideal target of monoclonal antibodies (mAbs). In particular, erenumab is the mAb that has shown good therapeutic efficacy in reducing pain intensity and having high tolerability. In this study, we aimed to investigate the efficacy of erenumab on both cognitive performance and psychological well-being. This was a pilot study with a retrospective design that included 14 subjects (2 males and 12 females), with a mean age of 52.29 ± 9.62, who attended the Headache and Migraine outpatient clinic of the IRCCS Centro Neurolesi Bonino-Pulejo of Messina. The evaluation consisted of measuring cognitive and psychological functioning. Comparing clinical and psychometric test scores between baseline and follow-up, we found a significant improvement in both cognitive performance and quality of life. We also observed a decrease in migraine disability. Our findings have shown improvements in global cognitive performance and quality of life in migraine patients taking erenumab.

Eptinezumab-jjmr, a humanized monoclonal specific to Calcitonin Gene Related Peptide, for the preventive treatment of migraine in adults

Purpose of Review

Migraines are prevalent and cause significant morbidity, decline in quality of life and healthcare costs universally. Treatment options are varied, but efficacy is limited. This review centers on Eptinezumab-jjmr, a humanized monoclonal specific to CGRP for the prevention of migraines in adults. Herein presented are the science and mechanism of action, indication and clinical evidence for use.

Recent Findings

Migraines are severe, recurrent headaches, which are either episodic or chronic in nature. The pain is severe, often accompanied by co-morbid symptoms, such as photophobia, phonophobia, nausea and emesis, and is limiting in nature. It is a prevalent disorder that causes significant, worldwide disability, morbidity, suffering, and costs.

The pathophysiology of migraines is actively studied, though recent research points to an initiating event causing migraine generation, that is then propagated by other brain regions, a significant one being the trigeminocervical complex. This is driven by biochemical transmitters, chiefly CGRP. This discovery led to the development of CGRP-targeting drugs, including gepants (small molecular antagonists) and anti-CGRP antibodies, such as Eptinezumab-jjmr.

Traditional therapy includes preventative and abortive treatment; however, adherence with preventative treatment has been historically poor, and certain types of abortive therapy carry risks and side effects that preclude them from a large patient population. Moreover, traditional therapy often falls short in migraine therapy. CGRP antagonist, including Eptinezumab, aims to cover the gaps in migraine therapy. We present here evidence to support the safe and effective use of Eptinezumab for the prevention of migraines.

Summary

Migraines are a prevalent primary headache disorder causing significant morbidity worldwide. Traditional abortive and preventative treatments fall short for many patients. Eptinezumab is part of new generation of CGRP-targeting medications and has shown significant evidence to support its use for the prevention of migraines. Further research is required to properly compare eptinezumab with existing pharmacotherapy and update guidelines on the appropriate combinations of therapies that are not available and the correct patient selection for each.

Characteristics, mechanism, and management of pain in atopic dermatitis: A literature review

Background

Atopic dermatitis (AD) is a chronic, pruritic, immune‐mediated inflammatory disease. Developments in basic science and clinical research have increased our understanding of AD. Although pain as a symptom of AD is underemphasized in previous studies, multiple researchers address pain as a frequent burden of AD. However, the exact role of pain in AD is not fully understood.

Aims

Our review aimed to summarize the current evidence focusing on characteristics, mechanism, and management of pain in AD.

Materials & Methods

We conducted a thorough literature review in the PubMed database to figure out different aspects discussing pain in AD, including pain symptoms, burden, the relationship between pain and itch, mechanism, and pain management in AD.

Results and Conclusion

AD patients affected by skin pain vary from 42.7%‐92.2% with remarkable intensity and heavy burden. Skin pain and itch interacted both in symptoms and mechanisms. Atopic skin with the impaired barrier, neurogenic inflammation mediators, peripheral and central sensitization of pain may possibly explain pain mechanism in AD. Future research is needed to clarify the commonality and disparity of pain and itch in AD in order to seek efficacious medications and treatment.

Monoclonal Antibodies for Chronic Pain Treatment: Present and Future

Chronic pain remains a major problem worldwide, despite the availability of various non-pharmacological and pharmacological treatment options. Therefore, new analgesics with novel mechanisms of action are needed. Monoclonal antibodies (mAbs) are directed against specific, targeted molecules involved in pain signaling and processing pathways that look to be very effective and promising as a novel therapy in pain management. Thus, there are mAbs against tumor necrosis factor (TNF), nerve growth factor (NGF), calcitonin gene-related peptide (CGRP), or interleukin-6 (IL-6), among others, which are already recommended in the treatment of chronic pain conditions such as osteoarthritis, chronic lower back pain, migraine, or rheumatoid arthritis that are under preclinical research. This narrative review summarizes the preclinical and clinical evidence supporting the use of these agents in the treatment of chronic pain.

Chronic Prostatitis and Pelvic Pain Syndrome: Another Autoimmune Disease?

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), characterized by chronic pain in the perineum or lower abdomen regions, is a frequent disorder in men. Previous studies demonstrated that the immune mediators, including interleukin (IL)-1β, IL-6, interferon-γ, tumor necrosis factor-α, and immunoglobulins, are elevated in the expressed prostate secretions and seminal fluid of CP/CPPS men. The memory T, T helper 1 (Th1), Th17, and Th22 cells increase in the peripheral blood of CP/CPPS men. Additionally, prostate antigens specific-autoreactive T cells are identified in CP/CPPS patients. After generally reviewing and comparing the inflammatory responses in autoimmune diseases and CP/CPPS, we presumed that CP/CPPS is more likely to be defined as an autoimmune disease. Thus, a better understanding of autoimmune diseases would contribute to a deeper understanding of the CP/CPPS and provide new inspirations for the treatment of this disease.

Pharmacologic agents directed at the treatment of pain associated with maladaptive neuronal plasticity

INTRODUCTION

The definition of nociplastic pain in 2016 has changed the way maladaptive chronic pain is viewed in that it may emerge without neural lesions or neural disease. Many endogenous and pharmacologic substances are being investigated for their role in treating the pain associated with neuronal plasticity.

AREAS COVERED

The authors review promising pharmacologic agents for the treatment of pain associated with maladaptive neuronal plasticity. The authors then provide the reader with their expert opinion and provide their perspectives for the future.

EXPERT OPINION

An imbalance between the amplification of ascending pain signals and the poor activation of descending inhibitory signals may be at the root of many chronic pain syndromes. The inhibitory activity of noradrenaline reuptake may play a role in neuropathic and nociplastic analgesia. A better understanding of the brain's pain matrix, its signaling cascades, and the complex bidirectional communication between the immune system and the nervous system may help meet the urgent and unmet medical need for safe, effective chronic pain treatment, particularly for pain with a neuropathic and/or nociplastic component.

Common and discrete mechanisms underlying chronic pain and itch: peripheral and central sensitization

Normally, an obvious antagonism exists between pain and itch. In normal conditions, painful stimuli suppress itch sensation, whereas pain killers often generate itch. Although pain and itch are mediated by separate pathways under normal conditions, most chemicals are not highly specific to one sensation in chronic pathologic conditions. Notably, in patients with neuropathic pain, histamine primarily induces pain rather than itch, while in patients with atopic dermatitis, bradykinin triggers itch rather than pain. Accordingly, repetitive scratching even enhances itch sensation in chronic itch conditions. Physicians often prescribe pain relievers to patients with chronic itch, suggesting common mechanisms underlying chronic pain and itch, especially peripheral and central sensitization. Rather than separating itch and pain, studies should investigate chronic itch and pain including neuropathic and inflammatory conditions. Here, we reviewed chronic sensitization leading to chronic pain and itch at both peripheral and central levels. Studies investigating the connection between pain and itch facilitate the development of new therapeutics against both chronic dysesthesias based on the underlying pathophysiology.

The Role of Anti-Nerve Growth Factor Monoclonal Antibodies in the Control of Chronic Cancer and Non-Cancer Pain

Nerve growth factor (NGF) belongs to the neurotrophin family and plays a fundamental role in the endurance of sensory and sympathetic neurons during embryogenesis. NGF, by interacting with tropomyosin receptor kinase A receptor (TrkA), modulates the pain pathway through the enhancement of the neurotrophic and nociceptor functions. Moreover, it has been demonstrated that NGF is upregulated in patients with chronic pain syndromes, which are difficult to treat. Thus, new non-pharmacological approaches, based on the use of different species-specific monoclonal antibodies (mAbs) targeting the NGF pathway, have been tested for the treatment of chronic pain in preclinical and clinical studies. With regard to preclinical investigations, anti-NGF mAbs have been used for the management of osteoarthritis (OA) and chronic low back pain animal models, with encouraging results. Moreover, anti-NGF mAb therapy is effective in animal models of neuropathic cancer pain. As regards patients with OA, although phase II and phase III clinical trials with tanezumab led to pain reduction, the safety was not observed in all these patients. Here, we review the preclinical and clinical studies on anti-NGF mAb therapy in chronic syndromes, dissect the role of NGF in pain transduction, and highlight the use of anti-NGF mAbs in humans.

Nerve growth factor interacts with CHRM4 and promotes neuroendocrine differentiation of prostate cancer and castration resistance

Nerve growth factor (NGF) contributes to the progression of malignancy. However, the functional role and regulatory mechanisms of NGF in the development of neuroendocrine prostate cancer (NEPC) are unclear. Here, we show that an androgen-deprivation therapy (ADT)-stimulated transcription factor, ZBTB46, upregulated NGF via ZBTB46 mediated-transcriptional activation of NGF. NGF regulates NEPC differentiation by physically interacting with a G-protein-coupled receptor, cholinergic receptor muscarinic 4 (CHRM4), after ADT. Pharmacologic NGF blockade and NGF knockdown markedly inhibited CHRM4-mediated NEPC differentiation and AKT-MYCN signaling activation. CHRM4 stimulation was associated with ADT resistance and was significantly correlated with increased NGF in high-grade and small-cell neuroendocrine prostate cancer (SCNC) patient samples. Our results reveal a role of the NGF in the development of NEPC that is linked to ZBTB46 upregulation and CHRM4 accumulation. Our study provides evidence that the NGF-CHRM4 axis has potential to be considered as a therapeutic target to impair NEPC progression.

Here, the authors discover that NGF, upregulated by transcription factor ZBTB46 in prostate cancer exposed to androgen therapy, promotes neuroendocrine differentiation. They show that NGF interacts with the GPCR CHRM4, that both NGF and CHRM4 are upregulated in highly metastatic prostate cancer and that targeting NGF reduces therapy resistance in a mouse xenograft model.

Deciphering the Allosteric Binding Mechanism of the Human Tropomyosin Receptor Kinase A ( hTrkA) Inhibitors

Access to cryptic binding pockets or allosteric sites on a kinase that present themselves when the enzyme is in a specific conformational state offers a paradigm shift in designing the next generation small molecule kinase inhibitors. The current work showcases an extensive and exhaustive array of in vitro biochemical and biophysical tools and techniques deployed along with structural biology efforts of inhibitor-bound kinase complexes to characterize and confirm the cryptic allosteric binding pocket and docking mode of the small molecule actives identified for hTrkA. Specifically, assays were designed and implemented to lock the kinase in a predominantly active or inactive conformation and the effect of the kinase inhibitor probed to understand the hTrkA binding and hTrkB selectivity. The current outcome suggests that inhibitors with a fast association rate take advantage of the inactive protein conformation and lock the kinase state by also exhibiting a slow off-rate. This in turn shifts the inactive/active state protein conformational equilibrium cycle, affecting the subsequent downstream signaling.

Interventions to chronic prostatitis/Chronic pelvic pain syndrome treatment. Where are we standing and what's next?

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a frustrating syndrome. The pathogenesis and state of the art treatment of CP/CPPS are not known. A wide variety of therapies including anti-inflammatories, antibiotics, alpha-blockers, neuropathic pain modulators, and 5α-reductase inhibitors are in practice. These treatment strategies focus on alleviating symptoms in specific domains without treating root-cause and therapeutic outcome is far from satisfactory. We review the literature on current pharmacological treatments for CP/CPPS in detail and suggest future perspectives to modify the treatment strategies. We suggest that introducing novel treatment strategies such as gene editing, and T_regs expressing chimeric receptors may improve the treatment outcomes by inducing immune tolerance and controlling expression of pro-inflammatory cytokines.

Novel Approaches to Persistent Pain Therapy

Persistent and neuropathic pain affects >15% of the global population. Apart from being an individual burden to the patient, persistent pain causes considerable subsequent costs in global healthcare systems. Despite the efforts of pharmaceutical companies to develop novel analgesics, pharmacological options for the therapy of persistent and/or neuropathic pain are limited. We discuss here novel approaches to persistent pain therapy that are independent of classical target-based drug discovery, focusing on individualized diagnostic technologies, improvement of existing therapies, and expansion of current pharmacological treatments and future techniques that may broaden pharmacological options for the individual treatment of persistent pain in patients.

Progressive Increase of Inflammatory CXCR4 and TNF-Alpha in the Dorsal Root Ganglia and Spinal Cord Maintains Peripheral and Central Sensitization to Diabetic Neuropathic Pain in Rats

Diabetic neuropathic pain (DNP) is a common and serious complication of diabetic patients. The pathogenesis of DNP is largely unclear. The proinflammation proteins, CXCR4, and TNF-α play critical roles in the development of pain, while their relative roles in the development of DNP and especially its progression is unknown. We proposed that establishment of diabetic pain models in rodents and evaluating the stability of behavioral tests are necessary approaches to better understand the mechanism of DNP. In this study, Von Frey and Hargreaves Apparatus was used to analyze the behavioral changes of mechanical allodynia and heat hyperalgesia in streptozotocin-induced diabetic rats at different phases of diabetes. Moreover, CXCR4 and TNF-α of spinal cord dorsal and dorsal root ganglia (DRG) were detected by western blotting and immunostaining over time. The values of paw withdrawal threshold (PWT) and paw withdrawal latencies (PWL) were reduced as early as 1 week in diabetic rats and persistently maintained at lower levels during the progression of diabetes as compared to control rats that were concomitant with significant increases of both CXCR4 and TNF-α protein expressions in the DRG at 2 weeks and 5 weeks (the end of the experiments) of diabetes. By contrast, CXCR4 and TNF-α in the spinal cord dorsal horn did not significantly increase at 2 weeks of diabetes while both were significantly upregulated at 5 weeks of diabetes. The results indicate that central sensitization of spinal cord dorsal may result from persistent peripheral sensitization and suggest a potential reference for further treatment of DNP.

Evidence for Transient Receptor Potential (TRP) Channel Contribution to Arthritis Pain and Pathogenesis

Based on clinical and preclinical evidence, Transient Receptor Potential (TRP) channels have emerged as potential drug targets for the treatment of osteoarthritis, rheumatoid arthritis, and gout. This review summarizes the relevant data supporting a role for various TRP channels in arthritis pain and pathogenesis, as well as the current state of pharmacological efforts to ameliorate arthritis symptoms in patient populations.