Tanezumab for chronic low back pain: a randomized, double-blind, placebo- and active-controlled, phase 3 study of efficacy and safety

Targeting nerve growth factor for pain relief: pros and cons

Nerve growth factor (NGF) is a neurotrophic protein that has crucial roles in survival, growth and differentiation. It is expressed in neuronal and non-neuronal tissues. NGF exerts its effects via two types of receptors including the high affinity receptor, tropomyosin receptor kinase A and the low affinity receptor p75 neurotrophin receptor highlighting the complex signaling pathways that underlie the roles of NGF. In pain perception and transmission, multiple studies shed light on the effects of NGF on different types of pain including inflammatory, neuropathic, cancer and visceral pain. Also, the binding of NGF to its receptors increases the availability of many nociceptive receptors such as transient receptor potential vanilloid 1, transient receptor potential ankyrin 1, N-methyl-D-aspartic acid, and P2X purinoceptor 3 as well as nociceptive transmitters such as substance P and calcitonin gene-related peptide. The role of NGF in pain has been documented in pre-clinical and clinical studies. This review aims to shed light on the role of NGF and its signaling in different types of pain.

A structured biomimetic nanoparticle as inflammatory factor sponge and autophagy-regulatory agent against intervertebral disc degeneration and discogenic pain

Lower back pain (LBP) is a common condition closely associated with intervertebral disc degeneration (IDD), causing a significant socioeconomic burden. Inflammatory activation in degenerated discs involves pro-inflammatory cytokines, dysregulated regulatory cytokines, and increased levels of nerve growth factor (NGF), leading to further intervertebral disc destruction and pain sensitization. Macrophage polarization is closely related to autophagy. Based on these pathological features, a structured biomimetic nanoparticle coated with TrkA-overexpressing macrophage membranes (TMNP@SR) with a rapamycin-loaded mesoporous silica core is developed. TMNP@SR acted like sponges to adsorbe inflammatory cytokines and NGF and delivers the autophagy regulator rapamycin (RAPA) into macrophages through homologous targeting effects of the outer engineered cell membrane. By regulating autophagy activation, TMNP@SR promoted the M1-to-M2 switch of macrophages to avoid continuous activation of inflammation within the degenerated disc, which prevented the apoptosis of nucleus pulposus cells. In addition, TMNP@SR relieved mechanical and thermal hyperalgesia, reduced calcitonin gene-related peptide (CGRP) and substance P (SP) expression in the dorsal root ganglion, and downregulated GFAP and c-FOS signaling in the spinal cord in the rat IDD model. In summary, TMNP@SR spontaneously inhibits the aggravation of disc inflammation to alleviate disc degeneration and reduce the ingress of sensory nerves, presenting a promising treatment strategy for LBP induced by disc degeneration.

Diagnosis and Treatment of Low Back Pain: Synopsis of the 2021 US Department of Veterans Affairs and US Department of Defense Clinical Practice Guideline

ABSTRACT

Low back pain is a significant issue in the US Department of Veterans Affairs and Department of Defense populations as well as the general US population at large. This type of pain can be distressing to those who experience its effects, leading patients to seek relief of their symptoms. In 2022, leadership within the US Department of Veterans Affairs and US Department of Defense approved a joint clinical practice guideline for the management of low back pain. The guideline provides evidence-based recommendations for assessing and managing low back pain. Development of the guideline included a systematic evidence review, which was guided by 12 key questions. A multidisciplinary team, which included clinical stakeholders, reviewed the evidence that was retrieved and developed 39 recommendations using the Grading of Recommendations Assessment, Development, and Evaluation system. The scope of the clinical practice guideline is broad; however, the authors have focused on key recommendations that are important for clinicians in the evaluation and nonoperative treatment of low back pain, including pharmacologic therapies and both noninvasive and invasive nonpharmacologic treatments.

A Randomized Placebo-Controlled Trial of the Anti-Nerve Growth Factor Antibody Tanezumab in Subjects With Cancer Pain Due to Bone Metastasis

BACKGROUND

This phase III, randomized, double-blind, placebo-controlled, parallel-group study assessed the efficacy and safety of tanezumab in subjects with cancer pain predominantly due to bone metastasis receiving background opioid therapy.

METHODS

Subjects were randomized (stratified by (1) tumor aggressiveness and (2) presence/absence of concomitant anticancer treatment) to placebo or tanezumab 20 mg. Treatment was administered by subcutaneous injection every 8 weeks for 24 weeks (3 doses) followed by a 24-week safety follow-up period. The primary outcome was change in daily average pain in the index bone metastasis cancer pain site (from 0 = no pain to 10 = worst possible pain) from baseline to week 8.

RESULTS

LS mean (SE) change in pain at week 8 was -1.25 (0.35) for placebo (n = 73) and -2.03 (0.35) for tanezumab 20 mg (n = 72). LS mean (SE) [95% CI] difference from placebo was -0.78 (0.37) [-1.52, -0.04]; P = .0381 with α = 0.0478. The number of subjects with a treatment-emergent adverse event during the treatment period was 50 (68.5%) for placebo and 53 (73.6%) for tanezumab 20 mg. The number of subjects with a prespecified joint safety event was 0 for placebo and 2 (2.8%) for tanezumab 20 mg (pathologic fracture; n = 2).

CONCLUSION

Tanezumab 20 mg met the primary efficacy endpoint at week 8. Conclusions on longer-term efficacy are limited since the study was not designed to evaluate the durability of the effect beyond 8 weeks. Safety findings were consistent with adverse events expected in subjects with cancer pain due to bone metastasis and the known safety profile of tanezumab. Clinicaltrials.gov identifier: NCT02609828.

Inhibition of Neurogenic Inflammatory Pathways Associated with the Reduction in Discogenic Back Pain

STUDY DESIGN

Retrospective cohort study.

PURPOSE

This study aimed to determine whether the initiation of anti-calcitonin gene-related peptide (CGRP inhibitor) medication therapy for migraines was also associated with improvements in back/neck pain, mobility, and function in a patient population with comorbid degenerative spinal disease and migraine.

OVERVIEW OF LITERATURE

CGRP upregulates pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-6, brain-derived neurotrophic factor, and nerve growth factor in spinal spondylotic disease, which results in disc degeneration and sensitization of nociceptive neurons. Although CGRP inhibitors can quell neurogenic inflammation in migraines, their off-site efficacy as a therapeutic target for discogenic back/neck pain conditions remains unknown.

METHODS

All adult patients diagnosed with spinal spondylosis and migraine treated with CGRP inhibitors at a single academic institution between 2017 and 2020 were retrospectively identified. Patient demographic and medical data, follow-up duration, migraine severity and frequency, spinal pain, functional status, and mobility before and after the administration of CGRP inhibitors were collected. Paired univariate analysis was conducted to determine significant changes in spinal pain, headache severity, and headache frequency before and after the administration of CGRP inhibitors. The correlation between changes in the spinal pain score and functional or mobility improvement was assessed with Spearman's rho.

RESULTS

In total, 56 patients were included. The mean follow-up time after the administration of CGRP inhibitors was 123 days for spinal pain visits and 129 days for migraine visits. Back/neck pain decreased significantly (p <0.001) from 6.30 to 4.36 after starting CGRP inhibitor therapy for migraine control. As recorded in the spine follow-up notes, 25% of patients experienced a functional improvement in the activities of daily living, and 17.5% experienced mobility improvement while taking CGRP inhibitors. Change in back/ neck pain moderately correlated (ρ=-0.430) with functional improvement but was not correlated with mobility improvement (ρ=-0.052).

CONCLUSIONS

Patients taking CGRP inhibitors for chronic migraines with comorbid degenerative spinal conditions experienced significant off-target reduction of back/neck pain.

Various Doses of Tanezumab in the Management of Chronic Low Back Pain (CLBP): A Pooled Analysis of 4,514 Patients

Chronic low back pain (CLBP) is a persistent and debilitating condition characterized by pain and discomfort in the lower back region that lasts more than 12 weeks. This review aims to determine the efficacy and safety of various doses of tanezumab for managing CLBP. The present meta-analysis was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and the Cochrane Handbook for Systematic Reviews of Intervention standards. We searched multiple databases, including PubMed, Cochrane Library, Excerpta Medica Database (EMBASE), Scopus, and Web of Science, to identify randomized controlled trials comparing tanezumab to placebo or different dosage regimens for CLBP in adult patients. The primary outcome was the mean change in low back pain intensity (LBPI) score baseline to the end of treatment. Secondary outcomes included adverse events and the degree of disability or impairment. A total of six studies were included in the meta-analysis. Analysis of the data showed that tanezumab 5 mg significantly reduced LBPI compared to placebo at all time points (mean deviation (MD) ranging from -0.31 to -0.5). Similarly, tanezumab 10 mg showed a significant reduction in LBPI compared to placebo at all time points (MD ranging from -0.48 to -0.84). However, tanezumab 5 mg showed significantly less reduction of LBPI compared to 10 mg at two, four, eight, and 12 weeks (MD ranging from 0.19 to 0.32). These findings suggest that tanezumab is an effective treatment for CLBP, with 5 mg and 10 mg doses providing clinically meaningful reductions in LBPI.

Different Dosage Regimens of Tanezumab for the Treatment of Chronic Low Back Pain: A Meta-analysis of Randomized Controlled Trials

OBJECTIVE

The aim of this study was to assess the efficacy of different dosage regimens of tanezumab among individuals living with chronic low back pain (CLBP).

METHODS

PubMed, Embase, The Cochrane Library, and other databases were searched from inception until August 2021. Randomized controlled trials investigating the efficacy and safety of tanezumab in individuals with CLBP were included. Data were extracted independently by 2 investigators and assessed the study quality by the Cochrane risk-of-bias tool. The measurements include low back pain intensity and Roland-Morris Disability Questionnaire. The incidence of adverse events and serious adverse events was set to assess the safety of tanezumab for CLBP.

RESULTS AND DISCUSSION

Three high-quality randomized controlled trials with 3414 patients were finally included in our analysis. Tanezumab, respectively, led to a notable decrease compared with placebo in low back pain intensity (mean difference, -0.62; 95% confidence interval [CI], -0.77 to -0.46; P < 0.01) and Roland-Morris Disability Questionnaire (mean difference, -0.64; 95% CI, -0.80 to -0.47; P = 0.01). In addition, no significant difference existed between tanezumab and placebo groups (risk ratio, 1.10; 95% CI, 0.81-1.49; P = 0.55) in the adverse events and (risk ratio, 1.06; 95% CI, 0.34-3.27; P = 0.93) serious adverse events.

CONCLUSIONS

Intravenous and subcutaneous tanezumab injections as treatment for improving CLBP have promising clinical application as its great improvement on all efficacy and its controllable safety issues. Furthermore, intravenous and subcutaneous tanezumab injections were proved to achieve excellent and long-term curative effect on CLBP through our subgroup analysis and comparison.

CDC Clinical Practice Guideline for Prescribing Opioids for Pain - United States, 2022

This guideline provides recommendations for clinicians providing pain care, including those prescribing opioids, for outpatients aged ≥18 years. It updates the CDC Guideline for Prescribing Opioids for Chronic Pain - United States, 2016 (MMWR Recomm Rep 2016;65[No. RR-1]:1-49) and includes recommendations for managing acute (duration of <1 month), subacute (duration of 1-3 months), and chronic (duration of >3 months) pain. The recommendations do not apply to pain related to sickle cell disease or cancer or to patients receiving palliative or end-of-life care. The guideline addresses the following four areas: 1) determining whether or not to initiate opioids for pain, 2) selecting opioids and determining opioid dosages, 3) deciding duration of initial opioid prescription and conducting follow-up, and 4) assessing risk and addressing potential harms of opioid use. CDC developed the guideline using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework. Recommendations are based on systematic reviews of the scientific evidence and reflect considerations of benefits and harms, patient and clinician values and preferences, and resource allocation. CDC obtained input from the Board of Scientific Counselors of the National Center for Injury Prevention and Control (a federally chartered advisory committee), the public, and peer reviewers. CDC recommends that persons with pain receive appropriate pain treatment, with careful consideration of the benefits and risks of all treatment options in the context of the patient's circumstances. Recommendations should not be applied as inflexible standards of care across patient populations. This clinical practice guideline is intended to improve communication between clinicians and patients about the benefits and risks of pain treatments, including opioid therapy; improve the effectiveness and safety of pain treatment; mitigate pain; improve function and quality of life for patients with pain; and reduce risks associated with opioid pain therapy, including opioid use disorder, overdose, and death.

The role of nerve fibers and their neurotransmitters in regulating intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) has been the major contributor to chronic lower back pain (LBP). Abnormal apoptosis, senescence, and pyroptosis of IVD cells, extracellular matrix (ECM) degradation, and infiltration of immune cells are the major molecular alternations during IVDD. Changes at tissue level frequently occur at advanced IVD tissue. Ectopic ingrowth of nerves within inner annulus fibrosus (AF) and nucleus pulposus (NP) tissue has been considered as the primary cause for LBP. Innervation at IVD tissue mainly included sensory and sympathetic nerves, and many markers for these two types of nerves have been detected since 1940. In fact, in osteoarthritis (OA), beyond pain transmission, the direct regulation of neuropeptides on functions of chondrocytes have attracted researchers' great attention recently. Many physical and pathological similarities between joint and IVD have shed us the light on the neurogenic mechanism involved in IVDD. Here, an overview of the advances in the nervous system within IVD tissue will be performed, with a discussion on in the role of nerve fibers and their neurotransmitters in regulating IVDD. We hope this review can attract more research interest to address neuromodulation and IVDD itself, which will enhance our understanding of the contribution of neuromodulation to the structural changes within IVD tissue and inflammatory responses and will help identify novel therapeutic targets and enable the effective treatment of IVDD disease.

Persistent muscle hyperalgesia after adolescent stress is exacerbated by a mild-nociceptive input in adulthood and is associated with microglia activation

Non-specific low back pain (LBP) is a major global disease burden and childhood adversity predisposes to its development. The mechanisms are largely unknown. Here, we investigated if adversity in young rats augments mechanical hyperalgesia and how spinal cord microglia contribute to this. Adolescent rats underwent restraint stress, control animals were handled. In adulthood, all rats received two intramuscular injections of NGF/saline or both into the lumbar multifidus muscle. Stress induced in rats at adolescence lowered low back pressure pain threshold (PPT; p = 0.0001) and paw withdrawal threshold (PWT; p = 0.0007). The lowered muscle PPT persisted throughout adulthood (p = 0.012). A subsequent NGF in adulthood lowered only PPT (d = 0.87). Immunohistochemistry revealed changes in microglia morphology: stress followed by NGF induced a significant increase in ameboid state (p < 0.05). Repeated NGF injections without stress showed significantly increased cell size in surveilling and bushy states (p < 0.05). Thus, stress in adolescence induced persistent muscle hyperalgesia that can be enhanced by a mild-nociceptive input. The accompanying morphological changes in microglia differ between priming by adolescent stress and by nociceptive inputs. This novel rodent model shows that adolescent stress is a risk factor for the development of LBP in adulthood and that morphological changes in microglia are signs of spinal mechanisms involved.

Design of a randomized, placebo-controlled, phase 2 study evaluating the safety and efficacy of tanezumab for treatment of schwannomatosis-related pain

BACKGROUND

Schwannomatosis (SWN) is a rare tumor suppressor syndrome that predisposes affected individuals to develop multiple schwannomas and, less often, meningiomas. The most common symptom is chronic, severe pain. No medications are broadly effective in treating SWN-associated pain. The clinical trial described in this manuscript is a phase 2, randomized, double-blind, placebo-controlled study investigating the safety and efficacy of tanezumab - a humanized monoclonal antibody that inhibits nerve growth factor - for treatment of SWN-related pain. As the first therapeutic trial for SWN-related pain, it also aims to evaluate trial endpoints, understand recruitment patterns, and improve clinical trial design in this rare disease.

AIMS

The primary objective of this trial is to assess the analgesic efficacy of subcutaneous tanezumab 10 mg in subjects with SWN who continue pre-existing pain therapy (excluding non-steroidal anti-inflammatory drugs). The secondary objective is to assess safety in this population. Exploratory objectives include assessment of pain features, quality of life, and predictive biomarkers.

METHODS

The study is comprised of four periods (pre-treatment, double-blind treatment, single-arm treatment, safety follow-up) across 10 months with a delayed-start trial design to allow all participants to receive tanezumab. Forty-six participants will be enrolled and randomized 1:1 to receive either tanezumab or placebo subcutaneously in the double-blind treatment period; all participants receive tanezumab during the single-arm treatment period.

CONCLUSIONS

This study is the first therapeutic trial for SWN patients and targets a biological driver of SWN-related pain. It aims to establish a model for future pain studies in SWN and other rare diseases.

CLINICAL TRIAL REGISTRATION

NCT04163419 on ClinicalTrials.gov.

Intradiscal Therapies for Lumbar Degenerative Disk Disease

Discogenic low back pain is a common musculoskeletal complaint in patients presenting to orthopaedic surgeons. In addition to surgical options, there are several nonsurgical intradiscal treatments that have gained interest, ranging from biologic, nonbiologic, cell-based, and molecular therapies. However, there is limited evidence for many of these techniques, and some are still in the clinical trial stage. We describe a broad overview of these intradiscal therapies, the mechanism of action, and the evidence behind them.

Clinical Meaningfulness of Response to Tanezumab in Patients with Chronic Low Back Pain: Analysis From a 56-Week, Randomized, Placebo- and Tramadol-Controlled, Phase 3 Trial

INTRODUCTION

A recent phase 3, randomized, placebo- and tramadol-controlled trial (56-week treatment/24-week safety follow-up) demonstrated efficacy of tanezumab 10 mg in patients with chronic low back pain (CLBP) and a history of inadequate response to standard-of-care analgesics. Here, we report on the clinical meaningfulness of treatment response in this study, focused on secondary measures of pain, interference with daily functions, overall disease status, and satisfaction with treatment.

METHODS

Patients received placebo (up to week 16; n = 406), subcutaneously administered (SC) tanezumab 5 mg (every 8 weeks; n = 407), SC tanezumab 10 mg (every 8 weeks; n = 407), or orally administered tramadol prolonged-release (100-300 mg/day; n = 605) for 56 weeks. Patient's global assessment of low back pain (PGA-LBP), Brief Pain Inventory-short form (BPI-sf), Treatment Satisfaction Questionnaire for Medication (TSQM), and modified Patient-Reported Treatment Impact (mPRTI) were assessed at weeks 16 and 56.

RESULTS

At week 16, significant (p < 0.05) improvements over placebo were evident with tanezumab for the PGA-LBP (10 mg) and most BPI-sf (both doses), TSQM (both doses), and mPRTI (both doses) items assessed. Improvements over baseline persisted for the PGA-LBP and BPI-sf at week 56. However, the magnitude of improvements was modestly lower at week 56 relative to week 16. Tramadol did not improve PGA-LBP or BPI-sf scores versus placebo at week 16. Most differences between tanezumab and tramadol at week 56 did not reach the level of statistical significance for all endpoints.

CONCLUSIONS

The totality of the evidence as captured by measures of pain, interference with daily function, patient overall assessment of disease status, and satisfaction with treatment demonstrates the clinically meaningful benefit of tanezumab for some patients with CLBP compared with placebo.

CLINICALTRIALS

gov: NCT02528253.

Contemporary perspectives on heterotopic ossification

Heterotopic ossification (HO) is the formation of ectopic bone that is primarily genetically driven (fibrodysplasia ossificans progressiva [FOP]) or acquired in the setting of trauma (tHO). HO has undergone intense investigation, especially over the last 50 years, as awareness has increased around improving clinical technologies and incidence, such as with ongoing wartime conflicts. Current treatments for tHO and FOP remain prophylactic and include NSAIDs and glucocorticoids, respectively, whereas other proposed therapeutic modalities exhibit prohibitive risk profiles. Contemporary studies have elucidated mechanisms behind tHO and FOP and have described new distinct niches independent of inflammation that regulate ectopic bone formation. These investigations have propagated a paradigm shift in the approach to treatment and management of a historically difficult surgical problem, with ongoing clinical trials and promising new targets.

Pharmacotherapy for Spine-Related Pain in Older Adults

As the population ages, spine-related pain is increasingly common in older adults. While medications play an important role in pain management, their use has limitations in geriatric patients due to reduced liver and renal function, comorbid medical problems, and polypharmacy. This review will assess the evidence basis for medications used for spine-related pain in older adults, with a focus on drug metabolism and adverse drug reactions. A PubMed/OVID search crossing common spine, neck, and back pain terms with key words for older adults and geriatrics was combined with common drug classes and common drug names and limited to clinical trials and age over 65 years. The results were then reviewed with identification of commonly used drugs and drug categories: nonsteroidal anti-inflammatories (NSAIDs), acetaminophen, corticosteroids, gabapentin and pregabalin, antispastic and antispasmodic muscle relaxants, tricyclic antidepressants (TCAs), serotonin-norepinephrine reuptake inhibitors (SNRIs), tramadol, and opioids. Collectively, 138 double-blind, placebo-controlled trials were the focus of the review. The review found a variable contribution of high-quality studies examining the efficacy of medications for spine pain primarily in the geriatric population. There was strong evidence for NSAID use with adjustments for gastrointestinal and renal risk factors. Gabapentin and pregabalin had mixed evidence for neuropathic pain. SNRIs had good evidence for neuropathic pain and a more favorable safety profile than TCAs. Tramadol had some evidence in older patients, but more so in persons aged < 65 years. Rational therapeutic choices based on geriatric spine pain diagnosis are helpful, such as NSAIDs and acetaminophen for arthritic and myofascial-based pain, gabapentinoids or duloxetine for neuropathic and radicular pain, antispastic agents for myofascial-based pain, and combination therapy for mixed etiologies. Tramadol can be well tolerated in older patients, but has risks of cognitive and classic opioid side effects. Otherwise, opioids are typically avoided in the treatment of spine-related pain in older adults due to their morbidity and mortality risk and are reserved for refractory severe pain. Whenever possible, beneficial geriatric spine pain pharmacotherapy should employ the lowest therapeutic doses with consideration of polypharmacy, potentially decreased renal and hepatic metabolism, and co-morbid medical disorders.

Sex-Related Pain Behavioral Differences following Unilateral NGF Injections in a Rat Model of Low Back Pain

Low back pain (LBP) is a globally prevalent and costly societal problem with multifactorial etiologies and incompletely understood pathophysiological mechanisms. To address such shortcomings regarding the role of neurotrophins in the underlying mechanisms of pain, an LBP model was developed in rats involving two unilateral intramuscular injections of nerve growth factor (NGF) into deep trunk muscles. To date, behavioral investigations of this NGF-LBP model have been limited, especially as it pertains to female pain behaviors. This study compared mechanical sensitivity to noxious (hyperalgesia) and non-noxious (hypersensitivity) stimuli in control and NGF-injected male and female rats through pain resolution. Although the baseline testing revealed no differences between males and females, NGF-injected females demonstrated prolonged ipsilateral deep trunk mechanical hyperalgesia that resolved seven days later than males. Moreover, females showed bilateral trunk mechanical sensitivity to noxious and non-noxious stimuli compared to only ipsilateral behaviors in males. Sex differences were also observed in the severity of behavioral responses, with females displaying greater mean differences from baseline at several timepoints. Overall, these NGF-LBP behavioral findings mirror some of the sex differences reported in the clinical presentation of LBP and accentuate the translatability of this NGF-LBP model. Future studies using this LBP-NGF model could help to elucidate the neurobiological mechanisms responsible for the development, severity, and/or resolution of muscular LBP as well as to provide insights into the processes governing the transition from acute to chronic LBP.

Advances in the management of fibromyalgia: what is the state of the art?

INTRODUCTION

Fibromyalgia (FM) is a chronic pain syndrome associated with fatigue, insomnia, dyscognition, and emotional distress. Critical illness mechanisms include central sensitization to nociceptive and non-nociceptive stimuli often resulting in hypersensitivity to all sensory input.

AREAS COVERED

The clinical presentation of FM can vary widely and therefore requires therapies tailored to each patient's set of symptoms. This manuscript examines currently prescribed therapeutic approaches supported by empirical evidence as well as promising novel treatments. Although pharmacological therapy until now has been only moderately effective for FM symptoms, it represents a critical component of every treatment plan.

EXPERT OPINION

Currently approved pharmacological therapies for FM symptoms have limited but proven effectiveness. Novel therapies with cannabinoids and naltrexone appear promising. Recent functional imaging studies of FM have discovered multiple brain network abnormalities that may provide novel targets for mechanism-based therapies. Future treatment approaches, however, need to improve more than clinical pain but also other FM domains like fatigue, insomnia, and distress.

Analgesic effects of nerve growth factor-directed monoclonal antibody on diabetic neuralgia in an animal model

Current treatment options for diabetic neuralgia are limited and unsatisfactory. Tanezumab, a monoclonal antibody that blocks nerve growth factor (NGF) signaling, has been shown to be effective in relieving the clinical symptoms of osteoarthritis pain, chronic low back pain, cancer pain induced by bone metastasis, and diabetic neuralgia. However, the clinical development of tanezumab has been terminated due to the risk of induction of rapidly progressive osteoarthritis (RPOA), and no other NGF antibodies have been examined for their ability to treat diabetic neuralgia in either animal models or clinical trials. In this study, a humanized high‐affinity NGF monoclonal antibody (mAb), huAb45 that could neutralize the interaction between NGF and its high‐affinity receptor TrkA. In a mouse diabetic neuralgia model, it effectively relieved neuropathic pain. This study may serve as the necessary foundation for future studies of huAb45 to potentially treat diabetic neuralgia.

The Therapeutic Effect of iMSC-Derived Small Extracellular Vesicles on Tendinopathy Related Pain Through Alleviating Inflammation: An in vivo and in vitro Study

Background

Tendinopathy is a common cause of tendon pain. However, there is a lack of effective therapies for managing tendinopathy pain, despite the pain being the most common complaint of patients. This study aimed to evaluate the therapeutic effect of small extracellular vesicles released from induced pluripotent stem cell-derived mesenchymal stem cells (iMSC-sEVs) on tendinopathy pain and explore the underlying mechanisms.

Methods

Rat tendinopathy model was established and underwent the injection of iMSC-sEVs to the quadriceps tendon one week after modeling. Pain-related behaviors were measured for the following four weeks. Tendon histology was assessed four weeks after the injection. To further investigate the potential mechanism, tenocytes were stimulated with IL-1β to mimic tendinopathy in vitro. The effect of iMSC-sEVs on tenocyte proliferation and the expression of proinflammatory cytokines were measured by CCK-8, RT-qPCR, and ELISA. RNA-seq was further performed to systematically analyze the related global changes and underlying mechanisms.

Results

Local injection of iMSC-sEVs was effective in alleviating pain in the tendinopathy rats compared with the vehicle group. Tendon histology showed ameliorated tendinopathy characteristics. Upon iMSC-sEVs treatment, significantly increased tenocyte proliferation and less expression of proinflammatory cytokines were observed. Transcriptome analysis revealed that iMSC-sEVs treatment upregulated the expression of genes involved in cell proliferation and downregulated the expression of genes involved in inflammation and collagen degeneration.

Conclusion

Collectively, this study demonstrated iMSC-sEVs protect tenocytes from inflammatory stimulation and promote cell proliferation as well as collagen synthesis, thereby relieving pain derived from tendinopathy. As a cell-free regenerative treatment, iMSC-sEVs might be a promising therapeutic candidate for tendinopathy.

Population Pharmacokinetics of Tanezumab Following Intravenous or Subcutaneous Administration to Patients with Osteoarthritis or Chronic Low Back Pain

AIMS

Describe population pharmacokinetics of intravenous (IV) and subcutaneous (SC) tanezumab across Phase 2b/3 studies of osteoarthritis (OA) and chronic low back pain (CLBP). Methods Data from 10 studies of IV or SC tanezumab (2.5-20 mg every 8 weeks for up to 56 weeks) were included in a multi-step analysis. In Step 1, a two-compartment model with linear and non-linear elimination (based on prior analysis of pre-2015 IV osteoarthritis studies) was expanded to include other pre-2015 studies. In Step 2, post-2015 SC studies were combined into the model. Steps 3 and 4 evaluated impact of baseline nerve growth factor (NGF) and treatment-emergent anti-drug antibodies (TE ADA).

RESULTS

SC bioavailability was estimated at 62-76%. The key disposition parameters CL, V_c , V_p , and KM were estimated to be 0.133 L·day^-1 , 2.6 L, 1.77 L and 31.2 μg·L^-1 . Plasma tanezumab concentration was predicted to reach C_max at 8.9- 11.2 days following single and multiple SC administration in typical patients within the dose range of SC Phase 3 studies (2.5-10 mg every 8 weeks). Exposure of a typical patient was similar between IV and SC for the second part of the dosing interval (weeks 4-8). Covariates selected on the absorption parameters were WT, age, sex, and injection site. Baseline NGF had minimal effect on maximum elimination capacity and TE ADA status was associated with slightly higher tanezumab clearance (6-7%).

CONCLUSION

Our model adequately described plasma tanezumab concentration versus time following IV or SC administration. WT was the most influential covariate with respect to absorption of tanezumab in comparison to patient population (OA and CLBP) or other demographics. There was no clinically relevant effect of baseline NGF or TE ADA on tanezumab PK.

DUSP-1 Induced by PGE2 and PGE1 Attenuates IL-1β-Activated MAPK Signaling, Leading to Suppression of NGF Expression in Human Intervertebral Disc Cells

The molecular mechanism of discogenic low back pain (LBP) involves nonphysiological nerve invasion into a degenerated intervertebral disc (IVD), induced by nerve growth factor (NGF). Selective cyclooxygenase (COX)-2 inhibitors are mainly used in the treatment of LBP, and act by suppressing the inflammatory mediator prostaglandin E₂ (PGE₂), which is induced by inflammatory stimuli, such as interleukin-1β (IL-1β). However, in our previous in vitro study using cultured human IVD cells, we demonstrated that the induction of NGF by IL-1β is augmented by a selective COX-2 inhibitor, and that PGE₂ and PGE₁ suppress NGF expression. Therefore, in this study, to elucidate the mechanism of NGF suppression by PGE₂ and PGE₁, we focused on mitogen-activated protein kinases (MAPKs) and its phosphatase, dual-specificity phosphatase (DUSP)-1. IL-1β-induced NGF expression was altered in human IVD cells by MAPK pathway inhibitors. PGE₂ and PGE₁ enhanced IL-1β-induced DUSP-1 expression, and suppressed the phosphorylation of MAPKs in human IVD cells. In DUSP-1 knockdown cells established using small interfering RNA, IL-1β-induced phosphorylation of MAPKs was enhanced and prolonged, and NGF expression was significantly enhanced. These results suggest that PGE₂ and PGE₁ suppress IL-1β-induced NGF expression by suppression of the MAPK signaling pathway, accompanied by increased DUSP-1 expression.

Nerve Growth Factor (NGF) Inhibitors and Related Agents for Chronic Musculoskeletal Pain: A Comprehensive Review

Musculoskeletal pain such as osteoarthritis (OA) and low back pain (LBP) are very common and contribute to enormous burden and societal costs, despite dramatic therapeutic advances over recent decades. Novel approaches and targeted therapies are required to satisfy the urgent unmet medical need of musculoskeletal pain relief in both conditions. Nerve growth factor (NGF) inhibitors have utilized novel mechanisms different from conventional drugs, which have a variety of gastrointestinal, cardiac, or renal adverse effects. Several phase 2/3 studies have been accomplished for these drugs, such as tanezumab, fasinumab, and tyrosine receptor kinase A (TrkA) inhibitors. We searched the literature using the PubMed database and clinical trials using ClinicalTrials.gov to identify original papers, meta-analyses as well as ongoing clinical trials assessing the efficacy and safety profile of these drugs. In this narrative review, we briefly overview the disease burden of musculoskeletal pain, the role of NGF signaling and its receptors in the genesis of pain, and the mechanisms of action of inhibitors of NGF signaling and downstream pathways, and then discuss the efficacy and safety of each investigational drug in OA and LBP. Finally, we briefly review two serious adverse effects of NGF inhibitors, namely rapidly progressive OA and sympathetic system effects, and conclude with possible barriers and potential research directions to overcome these.

Tanezumab for chronic low back pain: a long-term, randomized, celecoxib-controlled Japanese Phase III safety study

Aim & methods: This trial investigated long-term (56-week treatment/24-week follow-up) use of subcutaneous tanezumab (5 or 10 mg every 8 weeks) or oral celecoxib (200 mg/day) in Japanese patients with chronic low back pain. Results & conclusion: Tanezumab safety was consistent with previous studies, except overall adverse events (tanezumab 5 mg = 63.0%, tanezumab 10 mg = 54.8%, celecoxib = 67.4%) and events of abnormal peripheral sensation (tanezumab 5 mg = 9.8%, tanezumab 10 mg = 4.3%, celecoxib = 4.3%) were more frequent with 5 mg than 10 mg tanezumab. Joint safety event rates were 1.1% for tanezumab 5 mg, 2.2% for tanezumab 10 mg and 0% for celecoxib. All treatments improved pain and function throughout the treatment period. Clinical trial registration number: NCT02725411.

Targeting Neurotrophic Factors for Low Back Pain and Sciatica: A Systematic Review and Meta-analysis

OBJECTIVES

This meta-analysis aims to investigate the efficacy and safety of medicines that target neurotrophic factors for low back pain (LBP) or sciatica.

METHODS

We searched published and trial registry reports of randomised controlled trials evaluating the effect of medicines that target neurotrophic factors to LBP or sciatica in seven databases from inception to December 2020. Two reviewers independently identified studies, extracted data, and assessed the risk of bias and certainty in the evidence.

RESULTS

Nine studies (3349 participants) were included in the meta-analyses. Low certainty evidence showed that anti-NGF may reduce pain at four weeks (MD -6.63, 95% CI -8.51 to -4.76), and 12 weeks (MD -6.10, -8.34 to -3.87), and may increase adverse effects for chronic LBP (OR 1.16, 0.99-1.36). Higher doses of anti-NGF may offer a clinically important reduction in pain at the cost of increased adverse effects for chronic LBP. Very low certainty evidence showed that anti-NGF and glial cell line-derived neurotrophic factor (pro-GDNF) may not reduce pain for sciatica at four weeks (MD -1.40, -8.26-5.46), at 12 weeks (MD -2.91, -13.69-7.67), and may increase adverse effects for sciatica (OR 3.27, 1.78-6.00).

CONCLUSION

Anti-NGF may offer small reductions in pain intensity for chronic LBP. The effect may depend on the dose and types of medicines. For sciatica, anti-NGF or pro-GDNF may not reduce pain. Medicines that target neurotrophic factors for LBP or sciatica are associated with different adverse effects from commonly prescribed medicines for these conditions.

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.

Is Targeting Nerve Growth Factor Antagonist a New Option for Pharmacologic Treatment of Low Back Pain? A Supplemental Network Meta-Analysis of the American College of Physicians Guidelines

Objective: It has been found that targeting nerve growth factor antagonists (ANGF) have excellent effects in the treatment of chronic pain, and the current pharmacologic treatments have very limited effects on low back pain (LBP). Thus we conducted this network meta-analysis (NMA) to study the efficacy and safety of ANGF for the treatment of LBP, and to guide for clinical practice and further research.

Method: PubMed, Scopus, Embase, CNKI, and the Cochrane Library were searched from January 1980 to March 2021. A frequentist framework network meta-analysis with a random-effect model was performed. Ranking effects were calculated by surface under the cumulative ranking analysis (SUCRA) and clusterank analysis.

Results: This NMA identified 30 studies, involving 9,508 patients with LBP. ANGF reported both superior effect on pain relief {SUCRA 82.1%, SMD 0.89, 95% CI [(0.26,1.51)]} and function improvement {SUCRA 77.3%, SMD 0.93, 95% CI [(0.27,1.58)]} than placebo, and did not showed any higher risk of treatment-emergent adverse effects {RR 1.11, 95% CI [(0.97,1.27)]} or serious adverse effects {RR 1.03, 95% CI [(0.54,1.97)]}, but it was associate with a special risk of rapidly progressive osteoarthritis. ANGF displayed the greatest potential to be the most effective and safest treatment (cluster-rank value for function improvement and safety: 4266.96, for pain relief and safety: 4531.92).

Conclusion: ANGF could relieve pain and improve function effectively and are superior to other traditional drugs recommended by guidelines. Although no significant difference in tolerability and safety between ANGFs and placebo was found, the rapid progression of original osteoarthritis which may be related to the use of ANGFs still needs special attention and furtherly verification by clinical trials.

Systematic Review Registration: PROSPERO, identifier [CRD42021258033].

The role of a potential biomarker in patients with migraine: review and new insights

Introduction: The search for an ideal biomarker for migraine has persisted for a long time. There is plentiful evidence of potential biomarkers for migraine found in cerebrospinal fluid, blood, and saliva.Areas covered: Herein, the authors highlight and discuss the most promising candidates in the literature. An electronic search was performed for studies published between 2010 and 2020 in MEDLINE, PubMed, and EMBASE, related to potential biomarkers in migraine patients, found in cerebrospinal fluid, saliva, and serum, focusing on biomarkers that can be related to treatment and clinical outcomes.Expert opinion: An ideal biomarker, or a panel of biomarkers, could revolutionize the way we address and propose treatments for this disease. Once severe presentations and phenotypes have been identified using a reliable biomarker, patients could be treated at earlier disease stages with more specific medications. The most important biomarkers with the most significant levels of evidence comprised calcitonin gene-related peptide (CGRP), glutamate, nerve growth factor, some inflammatory (CRP, TNF-α, interleukins) and oxidative stress markers. CGRP was associated with episodic, chronic migraine and response to treatment. Pituitary adenylate cyclase-activating polypeptide is an emerging neuropeptide involved in migraine diagnostics and severity. New genetic and epigenetic biomarkers will be candidates for future research.

Comparative safety review of current treatment options for chronic low back pain and unmet needs: a narrative review

Introduction: The healthcare expenditures in the United States are substantial for the management of refractory, chronic low back pain (CLBP). The objective of this review is to summarize and evaluate the safety profiles of different pharmacological treatment options used in the management of CLBP.Areas covered: The authors conducted a search of randomized controlled trials (RCTs) assessing the safety profiles of different pharmacological agents used in the management of CLBP. This narrative review covered corticosteroids, opioids, antidepressants, gabapentinoids, nonsteroidal anti-inflammatory drugs, muscle relaxants, anti-nerve growth factor antibodies and topical agents, as monotherapy or in combination.Expert opinion: The risk-benefit ratio of a particular treatment is a subject driving the ongoing development of pharmaceuticals. The most commonly reported AEs across all drug classes are of gastrointestinal nature, followed by neurological and skin-related. These AEs include nausea, dizziness, constipation, arthralgia, headache, dry mouth, pruritus, etc. The majority of the AEs reported are not life-threatening, although they may lower patients' quality of life, thus, affecting their compliance. One of the biggest limitations of our review stems from the paucity of safety assessments in published RCTs. Advances in our understanding of the neurobiology of pain will promote development of new therapeutic strategies.

Targeting Nerve Growth Factor for Pain Management in Osteoarthritis-Clinical Efficacy and Safety

Nerve growth factor (NGF) is a neurotrophin that mediates pain sensitization in pathologic states, including osteoarthritis. In clinical trials, antibodies to NGF reduce pain and improve physical function due to osteoarthritis of the knee or hip and have a long duration of action. Rapidly progressive osteoarthritis is a dose-dependent adverse event with these agents, and additional joint safety signals, such as subchondral insufficiency fractures and increased rates of total joint replacement, are reported. The effects on pain and potential mechanisms behind these joint events both are of considerable importance in the consideration of future use of anti-NGF therapies for osteoarthritis.

Efficacy and safety of fasinumab in patients with chronic low back pain: a phase II/III randomised clinical trial

OBJECTIVES

To study the efficacy and safety of fasinumab in moderate-to-severe, chronic low back pain (CLBP).

METHODS

In this phase II/III, double-blind, placebo-controlled study, patients with CLBP aged ≥35 years with inadequate pain relief/intolerance to acetaminophen, non-steroidal anti-inflammatory drugs and opioids were randomised to fasinumab 6 or 9 mg subcutaneous every 4 weeks (Q4W), 9 mg intravenous every 8 weeks (Q8W) or placebo. Primary endpoint was change from baseline to week 16 in average daily low back pain intensity (LBPI) numeric rating score. Key secondary efficacy variables included Roland-Morris Disability Questionnaire (RMDQ) and Patient Global Assessment (PGA). The results are based on a modified intent-to-treat analysis of 563/800 planned patients when enrolment was stopped early given emerging signals of joint risk in other osteoarthritis (OA) studies at doses being tested here.

RESULTS

Significant placebo-adjusted LBPI reductions at week 16 were observed for fasinumab 9 mg Q4W and Q8W (least squares mean (standard error) -0.7 (0.3); both nominal p<0.05), but not 6 mg (-0.3 (0.3); p=0.39). RMDQ and PGA improvements to week 16 were greatest for fasinumab 9 mg intravenous. Numerically greater efficacy occurred in patients with, versus those without, peripheral OA (pOA) over 16 weeks. Treatment-emergent adverse events (AEs) occurred in 274/418 (65.6%) patients in the combined fasinumab groups and 94/140 (67.1%) placebo patients. Joint AEs, mostly rapid progressive OA type 1, were more frequent in the combined fasinumab groups (19 events in 16 patients (3.8%) vs 1 event in 1 patient (0.7%) for placebo); all except one occurred in pOA patients.

CONCLUSIONS

Fasinumab highest doses, but not lower dose, improved both CLBP pain and function. Most joint AEs occurred in pOA patients, consistent with earlier findings in symptomatic OA. Further study is needed of patients with CLBP with and without pOA to determine optimal benefit-risk.

Rat dorsal horn neurons primed by stress develop a long-lasting manifest sensitization after a short-lasting nociceptive low back input

Background

A single injection of nerve growth factor (NGF) into a low back muscle induces a latent sensitization of rat dorsal horn neurons (DHNs) that primes for a manifest sensitization by a subsequent second NGF injection. Repeated restraint stress also causes a latent DHN sensitization.

Objective

In this study, we investigated whether repeated restraint stress followed by a single NGF injection causes a manifest sensitization of DHNs.

Methods

Rats were stressed repeatedly in a narrow plastic restrainer (1 hour on 12 consecutive days). Control animals were handled but not restrained. Two days after stress paradigm, behavioral tests and electrophysiological in vivo recordings from single DHNs were performed. Mild nociceptive low back input was induced by a single NGF injection into the lumbar multifidus muscle just before the recording started.

Results

Restraint stress slightly lowered the low back pressure pain threshold (Cohen d = 0.83). Subsequent NGF injection increased the proportion of neurons responsive to deep low back input (control + NGF: 14%, stress + NGF: 39%; P = 0.041), mostly for neurons with input from outside the low back (7% vs 26%; P = 0.081). There was an increased proportion of neurons with resting activity (28% vs 55%; P = 0.039), especially in neurons having deep input (0% vs 26%; P = 0.004).

Conclusions

The results indicate that stress followed by a short-lasting nociceptive input causes manifest sensitization of DHNs to deep input, mainly from tissue outside the low back associated with an increased resting activity. These findings on neuronal mechanisms in our rodent model suggest how stress might predispose to radiating pain in patients.