Tanezumab for the treatment of pain from osteoarthritis of the knee

Osteoarthritis Pain

Joint pain is the hallmark symptom of osteoarthritis (OA) and the main reason for patients to seek medical assistance. OA pain greatly contributes to functional limitations of joints and reduced quality of life. Although several pain-relieving medications are available for OA treatment, the current intervention strategy for OA pain cannot provide satisfactory pain relief, and the chronic use of the drugs for pain management is often associated with significant side effects and toxicities. These observations suggest that the mechanisms of OA-related pain remain undefined. The current review mainly focuses on the characteristics and mechanisms of OA pain. We evaluate pathways associated with OA pain, such as nerve growth factor (NGF)/tropomyosin receptor kinase A (TrkA), calcitonin gene-related peptide (CGRP), C–C motif chemokine ligands 2 (CCL2)/chemokine receptor 2 (CCR2) and tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β), the NOD-like receptor (NLR) family, pyrin domain-containing protein 3 (NLRP3) inflammasome, and the Wnt/β-catenin signaling pathway. In addition, animal models currently used for OA pain studies and emerging preclinical studies are discussed. Understanding the multifactorial components contributing to OA pain could provide novel insights into the development of more specific and effective drugs for OA pain management.

Management of Knee Osteoarthritis: What Internists Need to Know

Knee osteoarthritis (OA) is a common and morbid condition. No disease-modifying therapies exist; hence the goals of current treatment are to palliate pain and to retain function. OA pain is significantly influenced by the placebo effect. Nonpharmacologic interventions are essential and have been shown to improve outcomes. Canes, unloading braces, and therapeutic heating/cooling may be valuable. Pharmacotherapy options include topical and oral nonsteroidal anti-inflammatory drugs, duloxetine, and periodic intra-articular glucocorticoids and hyaluronans. Opioids, intra-articular stem cells, and platelet-rich plasma are not recommended. Novel targets such as nerve growth factor are under investigation and may be approved soon for OA pain.

The Neuroimmune Interplay in Joint Pain: The Role of Macrophages

Chronic pain associated with joint disorders, such as rheumatoid arthritis (RA), osteoarthritis (OA) and implant aseptic loosening (AL), is a highly debilitating symptom that impacts mobility and quality of life in affected patients. The neuroimmune crosstalk has been demonstrated to play a critical role in the onset and establishment of chronic pain conditions. Immune cells release cytokines and immune mediators that can activate and sensitize nociceptors evoking pain, through interaction with receptors in the sensory nerve terminals. On the other hand, sensory and sympathetic nerve fibers release neurotransmitters that bind to their specific receptor expressed on surface of immune cells, initiating an immunomodulatory role. Macrophages have been shown to be key players in the neuroimmune crosstalk. Moreover, macrophages constitute the dominant immune cell population in RA, OA and AL. Importantly, the targeting of macrophages can result in anti-nociceptive effects in chronic pain conditions. Therefore, the aim of this review is to discuss the nature and impact of the interaction between the inflammatory response and nerve fibers in these joint disorders regarding the genesis and maintenance of pain. The role of macrophages is highlighted. The alteration in the joint innervation pattern and the inflammatory response are also described. Additionally, the immunomodulatory role of sensory and sympathetic neurotransmitters is revised.

Genome-wide association study of primary dysmenorrhea in the Taiwan Biobank validates associations near the NGF and IL1 gene loci

Using the Taiwan Biobank, we aimed to identify traits and genetic variations that could predispose Han Chinese women to primary dysmenorrhea. Cases of primary dysmenorrhea included those who self-reported "frequent dysmenorrhea" in a dysmenorrhea-related Taiwan Biobank questionnaire, and those who have been diagnosed with severe dysmenorrhea by a physician. Controls were those without self-reported dysmenorrhea. Customized Axiom-Taiwan Biobank Array Plates were used to perform whole-genome genotyping, PLINK was used to perform association tests, and HaploReg was used to conduct functional annotations of SNPs and bioinformatic analyses. The GWAS analysis included 1186 cases and 24,020 controls. We identified 53 SNPs that achieved genome-wide significance (P < 5 × 10^-8, which clustered in 2 regions. The first SNP cluster was on chromosome 1, and included 24 high LD (R² > 0.88) variants around the NGF gene (lowest P value of 3.83 × 10^-13 for rs2982742). Most SNPs occurred within NGF introns, and were predicted to alter regulatory binding motifs. The second SNP cluster was on chromosome 2, including 7 high LD (R² > 0.94) variants around the IL1A and IL1B loci (lowest P value of 7.43 × 10^-10 for rs11676014) and 22 SNPs that did not reach significance after conditional analysis. Most of these SNPs resided within IL1A and IL1B introns, while 2 SNPs may be in the promoter histone marks or promoter flanking regions of IL1B. To conclude, data from this study suggest that NGF, IL1A, and IL1B may be involved in the pathogenesis of primary dysmenorrhea in the Han Chinese in Taiwan.

Efficacy and safety of biologic agents for the treatment of osteoarthritis: a meta-analysis of randomized placebo-controlled trials

Background:

We aimed to evaluate the efficacy and safety of biologic agents targeting three main cytokines, that is, nerve growth factor (NGF), interleukin-1 (IL-1), and tumor necrosis factor-α (TNF-α), for osteoarthritis (OA) treatment.

Methods:

Databases (PubMed, Embase, and Cochrane Library) and ClinicalTrials.gov were systematically searched for randomized placebo-controlled trials (RCTs) of biologic agents from inception to November 15, 2020. The outcomes were the mean change in pain, function scores, and the risk of adverse effects (AEs).

Results:

Out of the 28 studies with 29 RCTs (8555 individuals) included, biologic agents were superior to placebo in pain relief (standardized mean difference [SMD] = 0.28, 95% confidence interval [CI] = 0.17–0.38, p < 0.001) and function improvement (SMD = 0.30, 95% CI = 0.18–0.43, p < 0.001). The incidence of any AEs (risk ratio [RR] = 1.09, 95% CI = 1.05–1.14, p < 0.001) and discontinuations due to AEs (RR = 1.39, 95% CI = 1.05–1.83, p = 0.021) were higher following treatment with biologic agents while no significant difference was found in serious AEs. Subgroup analyses showed that NGF inhibitors provided superior pain relief (SMD = 0.36, 95% CI = 0.26–0.47, p < 0.001) and function improvement (SMD = 0.41, 95% CI = 0.30–0.51, p < 0.001), whereas IL-1 inhibitors and TNF-α inhibitors did not. Meanwhile, NGF inhibitors increased the incidence of any AEs (RR = 1.12, 95% CI = 1.07–1.17, p < 0.001) and discontinuations due to AEs (RR = 1.48, 95% CI = 1.07–2.06, p = 0.018). IL-1 inhibitors and TNF-α inhibitors showed no difference in safety compared with placebo.

Conclusions:

The efficacy and safety of biologic agents vary by mechanism of action. NGF inhibitors can relieve OA-related pain and improve function but involve safety concerns. IL-1 inhibitors and TNF-α inhibitors are relatively safe options but with limited efficacy.

Hierarchical functional nanoparticles boost osteoarthritis therapy by utilizing joint-resident mesenchymal stem cells

Utilization of joint-resident mesenchymal stem cells (MSC) to repair articular cartilage is a promising strategy in osteoarthritis (OA) therapy but remains a considerable research challenge. Here, hierarchical targeting and microenvironment responsive peptide functionalized nanoparticles (NPs) are used to achieve cartilage repair in situ. Ultrasmall copper oxide (CuO) NPs are conjugated with type 2 collagen and MSC dual-targeting peptide (designated WPV) with a matrix metalloproteinase 2 (MMP-2)-sensitive sequence as a spacer to achieve hierarchical targeting. Guided by this peptide, WPV-CuO NPs initially penetrate cartilage and subsequently expose the inner MSC-targeted peptide to attract MSCs through MMP-2 clearance. CuO further promotes chondrogenesis of MSCs. In an anterior cruciate ligament transection rat model, intraarticular injection of WPV-CuO NPs induces significant reduction of cartilage destruction. The therapeutic mechanism involves inhibition of the PI3K/AKT/mTOR pathway, as determined via transcriptome analysis. In conclusion, a novel therapeutic strategy for OA has been successfully developed based on localized MSC recruitment and cartilage repair without transplantation of exogenous cells or growth factors.

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.

Based on minimal clinically important difference values, a moderate dose of tanezumab may be a better option for treating hip or knee osteoarthritis: a meta-analysis of randomized controlled trials

Background:

Tanezumab is a nerve growth factor monoclonal antibody that may regulate pain in hip or knee osteoarthritis (OA). This meta-analysis was performed to evaluate the efficacy and safety of low and moderate doses of tanezumab in treating hip or knee OA.

Methods:

PubMed, EMBASE, the Cochrane Library, and Web of Science were comprehensively searched for clinical trials published before 1 May 2021. Patients were assessed via efficacy and safety outcomes.

Results:

Twelve randomized controlled trials including 6022 patients were identified. Both low and moderate doses of tanezumab significantly improved efficacy outcomes. However, only the point estimates (mean difference, MD) of moderate-dose tanezumab significantly exceeded the minimal clinically important differences (MCIDs). There were no significant differences in the incidence of treatment-related adverse events (AEs), withdrawals due to AEs, serious AEs, and total joint replacement between the tanezumab and placebo groups, whereas the incidence of AEs was higher in the tanezumab group (relative risk, RR = 1.10; 95% confidence interval, 95% CI = 1.04–1.17). The incidence of rapidly progressive OA was significantly higher in the combined low- and moderate-dose tanezumab groups than in the placebo group (RR = 5.01; 95% CI = 1.17–21.33). Furthermore, both low and moderate doses of tanezumab significantly increased the incidence of abnormal peripheral sensation (RR = 1.99, 95% CI = 1.21–3.28; RR = 2.64, 95% CI = 1.91–3.67, respectively). Compared with nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids, tanezumab showed significantly improved efficacy outcomes (p < 0.05). However, the point estimates (MD) of tanezumab were not greater than the MCID. Pooled analysis showed no significant differences between tanezumab and NSAIDs and opioids in safety outcomes (p > 0.05).

Conclusion:

Tanezumab is efficacious in patients with hip or knee OA. Tanezumab is relatively well tolerated and safe but increases the incidence of AEs and reversible abnormal peripheral sensation. Additional studies on the occurrence of rapidly progressive OA are needed. A moderate dose of tanezumab may maximize the benefits for hip or knee OA.

MicroRNA-128-3p suppresses interleukin-1β-stimulated cartilage degradation and chondrocyte apoptosis via targeting zinc finger E-box binding homeobox 1 in osteoarthritis

Accumulating studies have suggested that microRNAs (miRNAs) play vital roles in the pathogenesis of osteoarthritis (OA). Nevertheless, the specific function of miR-128-3p in OA remains unknown. In this study, we demonstrated that miR-128-3p was decreased and ZEB1 was increased in OA. Additionally, miR-128-3p expression was negatively correlated with ZEB1. miR-128-3p overexpression or ZEB1 silencing attenuated extracellular matrix degradation and cell apoptosis, and increased the proliferation of IL-1β-activated CHON-001 cells. Furthermore, ZEB1 was directly targeted by miR-128-3p. In addition, ZEB1 upregulation restored the effects of miR-128-3p overexpression on OA progression. Overall, our findings suggested that miR-128-3p might regulate the development of OA via targeting ZEB1.

Relative Efficacy and Safety of Tanezumab for Osteoarthritis: A Systematic Review and Meta-analysis of Randomized-Controlled Trials

OBJECTIVES

The aim of this meta-analysis was to evaluate the efficacy and safety of tanezumab for the treatment of patients with knee or hip osteoarthritis (OA).

METHODS

PubMed, Embase, Cochrane Central Register of Controlled Trials, and Web of Science were searched from inception to July 2020. Randomized-controlled trials comparing tanezumab with placebo or nonsteroidal anti-inflammatory drugs in patients with OA. Two investigators identified studies and independently extracted data, and conventional meta-analyses were conducted with Review Manager 5.3. The outcomes were pain relief, functional improvement, and risk of adverse events (AEs).

RESULTS

A total of 8 articles, comprising 9 randomized-controlled trials, were included. Overall, tanezumab was superior to placebo for relieving pain and improving function, as well as in the patient's global assessment. Tanezumab also had significant advantages over nonsteroidal anti-inflammatory drugs for relieving pain and improving function, as well as in the patient's global assessment. Significantly more patients discontinued treatment because of AEs after treatment with tanezumab. However, the differences in serious AEs and total joint replacement were not significant. Moreover, tanezumab-treated patients experienced significantly more rapid progression of osteoarthritis.

DISCUSSION

Tanezumab can alleviate pain and improve function for patients with OA of the hip or knee. Although tanezumab does not cause serious AEs, rapid progression of OA occurred in a small number of participants, so more clinical trials are needed to explore its safety.

Clinically Relevant Molecular Biomarkers for Use in Human Knee Osteoarthritis: A Systematic Review

OBJECTIVE

Biomarkers in osteoarthritis (OA) could serve as objective clinical indicators for various disease parameters, and act as surrogate endpoints in clinical trials for disease-modifying drugs. The aim of this systematic review was to produce a comprehensive list of candidate molecular biomarkers for knee OA after the 2013 ESCEO review and discern whether any have been studied in sufficient detail for use in clinical settings.

DESIGN

MEDLINE and Embase databases were searched between August 2013 and May 2018 using the keywords "knee osteoarthritis," "osteoarthritis," and "biomarker." Studies were screened by title, abstract, and full text. Human studies on knee OA that were published in the English language were included. Excluded were studies on genetic/imaging/cellular markers, studies on participants with secondary OA, and publications that were review/abstract-only. Study quality and bias were assessed. Statistically significant data regarding the relationship between a biomarker and a disease parameter were extracted.

RESULTS

A total of 80 studies were included in the final review and 89 statistically significant individual molecular biomarkers were identified. C-telopeptide of type II collagen (CTXII) was shown to predict progression of knee OA in urine and serum in multiple studies. Synovial fluid vascular endothelial growth factor concentration was reported by 2 studies to be predictive of knee OA progression.

CONCLUSION

Despite the clear need for biomarkers of OA, the lack of coordination in current research has led to incompatible results. As such, there is yet to be a suitable biomarker to be used in a clinical setting.

Disease-modifying therapeutic strategies in osteoarthritis: current status and future directions

Osteoarthritis (OA) is the most common form of arthritis. It is characterized by progressive destruction of articular cartilage and the development of chronic pain and constitutes a considerable socioeconomic burden. Currently, pharmacological treatments mostly aim to relieve the OA symptoms associated with inflammation and pain. However, with increasing understanding of OA pathology, several potential therapeutic targets have been identified, enabling the development of disease-modifying OA drugs (DMOADs). By targeting inflammatory cytokines, matrix-degrading enzymes, the Wnt pathway, and OA-associated pain, DMOADs successfully modulate the degenerative changes in osteoarthritic cartilage. Moreover, regenerative approaches aim to counterbalance the loss of cartilage matrix by stimulating chondrogenesis in endogenous stem cells and matrix anabolism in chondrocytes. Emerging strategies include the development of senolytic drugs or RNA therapeutics to eliminate the cellular or molecular sources of factors driving OA. This review describes the current developmental status of DMOADs and the corresponding results from preclinical and clinical trials and discusses the potential of emerging therapeutic approaches to treat OA.

Effectiveness of Various Dosages and Administration Methods of Tanezumab for the Treatment of Pain in Knee and Hip Osteoarthritis: a Network Meta-Analysis

BACKGROUND

Previous meta-analyses have reported the superiority of tanezumab versus placebo in the treatment of osteoarthritis (OA). However, they did not compare different injection methods (intravenous or subcutaneous), doses of injection.

OBJECTIVE

The goal of this network meta-analysis (NMA) was to evaluate the therapeutic effects of different dosages and methods of injection of tanezumab on relieving pain in patients with OA.

METHODS

An online systematic search was performed by using the PubMed, Cochrane Library, EMBASE, and ClinicalTrials.gov databases from inception to November 9, 2019. The goal was to identify randomized controlled trials (RCTs) that concentrated on the therapeutic effects of different dosages and methods of injection of tanezumab in patients with OA. The pairwise meta-analyses with the fixed effects model were undertaken with the "meta" package using R 3.6.0 programming language. In addition, an NMA with fixed effects was assessed using a gemtc software. The surface under the cumulative ranking curve value of each intervention was calculated to obtain a hierarchy of treatments.

RESULTS

Of the 328 RCTs identified through the literature search, 12 RCTs were included in the current NMA. In terms of the Western Ontario and McMaster Universities Osteoarthritis Index pain and physical function subscales, the most effective treatment was intravenous injection of tanezumab (10 mg; surface under the cumulative ranking curve values of 90% and 88%, respectively), and the least effective therapy was subcutaneous injection of tanezumab (2.5 mg; 20% and 19%).

CONCLUSIONS

To achieve high therapeutic efficacy and avoid treatment failure, an intravenous injection of tanezumab (10 mg) is recommended as an efficacious therapy, facilitating pain relief in patients with OA. However, this conclusion may also be affected by the limitations of this study owing to the small sample size and data heterogeneity, and further research should therefore be conducted to eliminate these limitations and to confirm the findings.

A harm reduction model to assess the impact of new treatments for pain over standard of care among patients with osteoarthritis

BACKGROUND: Osteoarthritis (OA) affects millions of adults in the United States and can result in substantial pain, functional impairment, and significant clinical and economic burden. To manage chronic pain associated with OA, treatment guidelines recommend a variety of pharmacologic treatments, including traditional oral nonsteroidal anti-inflammatory drugs (NSAIDs), cyclooxygenase-2 inhibitors (COX-2s), and opioids. While these drug treatments can be effective at pain management, they are also associated with significant clinical and economic burden. New treatments for chronic pain among patients with OA of the hip and/or knee have the potential to reduce the occurrence of such negative clinical outcomes, including cardiovascular events, renal events, and opioid use disorder (OUD), thereby reducing health care resource use (HRU) and medical costs. OBJECTIVE: To develop a harm reduction model (HRM) to assess potential reductions of negative clinical outcomes, HRU, and medical costs associated with the use of new treatments in place of oral NSAIDs, tramadol, and non-tramadol opioids among patients with OA of the hip and/or knee in the United States. METHODS: The HRM model integrated findings from the literature and inputs from a variety of sources, along with assumptions regarding potential ability of new treatments to replace existing treatments and market penetration into a unified framework to estimate outcomes and costs. The model outputs included estimated per-patient and population-level reductions in negative clinical outcomes associated with prescribing new treatments in place of oral NSAIDs or opioids along with number needed to treat (NNT) associated with new treatments. The model assumed that new treatments will primarily be used in place of non-tramadol opioids, but more modest adoption in place of oral NSAIDs and tramadol. RESULTS: Among patients with OA of the hip and/or knee who were prescribed oral NSAIDs, tramadol, or non-tramadol opioids for chronic use (≥ 90 days), the HRM estimated total cost savings of $3.8 billion, $5.1 billion, and $29.9 billion, respectively, from prescribing new treatments for OA pain over a 36-month period. The reduced economic burden was driven by significant reductions in the incidence of negative clinical outcomes. Estimates of the NNT to avoid a negative clinical event related to NSAID and opioid treatment initiation were low for most outcomes. Estimates of NNT associated with NSAID use ranged from 4 to 17 patients, depending on outcome, and estimates of NNT associated with opioid use was 35 non-tramadol and 134 tramadol patients for OUD and ranged from 6 to 21 patients for the other clinical outcomes, depending on treatment and outcome. CONCLUSIONS: Results from the HRM suggest that prescribing new treatments in place of oral NSAIDs and/or opioids for OA pain results in a potentially substantial reduction in patients experiencing negative clinical outcomes and reductions in all-cause HRU and costs. DISCLOSURES: This study was sponsored by Pfizer and Eli Lilly and Company. Silverman was a paid consultant to Pfizer and Eli Lilly and Company in connection with this study. Beck and Schepman are employees of Pfizer with stock and/or stock options. Robinson is an employee and minor stockholder of Eli Lilly and Company. Rice, White, and Fernan are employees of the Analysis Group, who were paid consultants to Pfizer and Eli Lilly and Company for this study and development of the manuscript.

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.

Emerging and New Treatment Options for Knee Osteoarthritis

Osteoarthritis (OA) is the most prevalent type of arthritis worldwide, resulting in pain and often chronic disability and a significant burden on healthcare systems globally. Non-steroidal anti-inflammatory drugs (NSAIDs), analgesics, intra-articular corticosteroid injections are of little value in the long term, and opioids may have ominous consequences. Radiotherapy of knee OA has no added value. Physical therapy, exercises, weight loss, and lifestyle modifications may give pain relief, improve physical functioning and quality of life. However, no single treatment has regenerating potential for damaged articular cartilage. Due to a better understanding of osteoarthritis, innovative new treatment options have been developed. In this narrative review, we focus on emerging OA knee treatments, relieving symptoms, and regenerating damaged articular cartilage that includes intra-articular human serum albumin, conventional disease-modifying anti-rheumatic drugs (DMARDs), lipid-lowering agents (statin), nerve growth factors antagonists, bone morphogenetic protein, fibroblast growth factors, Platelet-Rich Plasma (PRP), Mesenchymal Stem Cells (MSC), exosomes, interleukin-1 blockers, gene-based therapy, and bisphosphonate.

Frunevetmab, a felinized anti-nerve growth factor monoclonal antibody, for the treatment of pain from osteoarthritis in cats

BACKGROUND

Frunevetmab, a felinized antinerve growth factor monoclonal antibody, effectively decreases osteoarthritis (OA) pain in cats.

OBJECTIVE

To evaluate the efficacy of frunevetmab given at monthly intervals in a randomized, placebo-controlled, parallel-group, double-blind superiority study.

ANIMALS

Two hundred seventy-five client-owned cats with naturally-occurring OA pain and associated mobility impairment and disability.

METHODS

Randomized, placebo-controlled, parallel-group, double-blind, superiority study. Following screening, cats received frunevetmab (nominal dose of 1.0 mg/kg, SC [effective dose range of 1.0-2.8 mg/kg]) or placebo on days 0, 28, and 56. Outcome measures were owner questionnaires and veterinary physical and orthopedic evaluations at days 28, 56, and 84. Success/failure rates (and numbers needed treat, NNT) and change in scores (and standardized effect size, ES) were analyzed.

RESULTS

Frunevetmab (182) and placebo (93) treated cats were enrolled and received at least 1 treatment. Significant improvement with frunevetmab over placebo occurred at days 28 and 56 for the client specific outcome measures (CSOM) questionnaire (success rates and total scores [NNT of 9 and ES of 0.3 at day 56]); at days 28 and 56 for owner-assessed global treatment response; and at days 56 and 84 for veterinarian-assessed joint pain (ES of 0.18 at day 56). Adverse events did not differ between groups, except skin disorders which collectively occurred significantly more frequently in frunevetmab treated (32/182 cats) vs placebo (8/93 cats).

CONCLUSIONS AND CLINICAL IMPORTANCE

Frunevetmab has the potential to address a critical gap in the treatment of pain because of osteoarthritis in cats.

Association of Diabetic Peripheral Neuropathy with Vitamin D Levels Depends on Vitamin D Status

Background

Vitamin D deficiency has been reported to be associated with diabetic peripheral neuropathy (DPN). Our objective here was to evaluate the association between vitamin D levels and neuropathic symptoms in a Chinese population.

Material/Methods

A total of 4435 patients with type 2 diabetes (T2D) were recruited in this cross-sectional study. 25-dihydroxyvitamin D (25-(OH) D) serum concentration was measured by electrochemiluminescence assay (Cobas e601, Roche). DPN was clinically diagnosed by assessing neurological symptoms and performing current perception threshold (CPT) testing. Of all the patients, 2910 were CPT-positive and had assessed neurological symptoms.

Results

In the vitamin D insufficiency group (<30 ng/mL 25-(OH) D), patients with neurological symptoms had higher serum 25-(OH) D levels than those without neurological symptoms (24.65±3.42 ng/mL vs 23.61±4.54 ng/mL, p≤0.001). The risk of numbness and pain increased by 0.5-fold for every 6 ng/mL increase in 25-(OH) D. In the vitamin D sufficiency group (≥30 ng/mL 25-(OH) D), patients with neurological symptoms had lower serum 25-(OH) D levels than those without neurological symptoms (32.96±3.18 ng/mL vs 33.45±4.27 ng/mL, p<0.01). For every 4 ng/mL decrease in 25-(OH) D, the risk of numbness and pain increased by 0.2-fold.

Conclusions

The association of neuropathy symptoms with 25-(OH) D levels differed depending on whether the patients had insufficient or sufficient vitamin D.

Roles of mechanosensitive channel Piezo1/2 proteins in skeleton and other tissues

Mechanotransduction is a fundamental ability that allows living organisms to receive and respond to physical signals from both the external and internal environments. The mechanotransduction process requires a range of special proteins termed mechanotransducers to convert mechanical forces into biochemical signals in cells. The Piezo proteins are mechanically activated nonselective cation channels and the largest plasma membrane ion channels reported thus far. The regulation of two family members, Piezo1 and Piezo2, has been reported to have essential functions in mechanosensation and transduction in different organs and tissues. Recently, the predominant contributions of the Piezo family were reported to occur in the skeletal system, especially in bone development and mechano-stimulated bone homeostasis. Here we review current studies focused on the tissue-specific functions of Piezo1 and Piezo2 in various backgrounds with special highlights on their importance in regulating skeletal cell mechanotransduction. In this review, we emphasize the diverse functions of Piezo1 and Piezo2 and related signaling pathways in osteoblast lineage cells and chondrocytes. We also summarize our current understanding of Piezo channel structures and the key findings about PIEZO gene mutations in human diseases.

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.

TrkA specific signalling pathways are critical for mechanical allodynia development and bone alterations in a mouse model of rheumatoid arthritis

ABSTRACT

Rheumatoid arthritis is frequently associated with chronic pain that still remains difficult to treat. Targeting nerve growth factor (NGF) seems very effective to reduce pain in at least, osteoarthritis and chronic low back pain but leads to some potential adverse events. Our aim was to better understand the involvement of the intracellular signalling pathways activated by NGF through its specific tyrosine kinase type A (TrkA) receptor in the pathophysiology of rheumatoid arthritis using the complete Freund adjuvant model in our knock-in TrkA/C mice. Our multimodal study demonstrated that knock-in TrkA/C mice exhibited a specific decrease of mechanical allodynia, weight bearing deficit, peptidergic (CGRP+) and sympathetic (TH+) peripheral nerve sprouting in the joints, a reduction in osteoclast activity and bone resorption markers, and a decrease of CD68 positive cells in the joint with no apparent changes in joint inflammation compared to WT mice following arthritis. Finally, transcriptomic analysis show several differences in DRGs mRNA expression of putative mechanotransducers such as ASIC3 and TRAAK as well as intracellular pathways such as c-Jun in the joint/DRGs. These results suggest that TrkA specific intracellular signalling pathways are specifically involved in mechanical hypersensitivity and bone alterations following arthritis using TrkA/C mice.

A novel mice model of acute flares in osteoarthritis elicited by intra-articular injection of cultured mast cells

PURPOSE

Mast cells are multifunctional in osteoarthritis (OA), and infiltration of activated mast cells likely contributes to disease severity and progression. However, the detailed mechanisms of action are unclear. The purpose of this study was to elucidate the role of mast cell infiltration in OA at histological level using a new mice model and to investigate pharmacological inhibitory effects of existing mast cell stabilizers in this model.

METHODS

Mice were injected intra-articularly with monosodium iodoacetate (MIA 0.5 mg) or PBS on day 0, and PBS, with or without mast cells (MC: 1 × 10⁶ cells) on day 14. They were divided into four groups: OA flare (MIA + MC), OA (MIA + PBS), MC non-OA (PBS + MC), and PBS non-OA (PBS + PBS). In OA flare, the MC stabilizer drug (tranilast: 400 mg/kg/day) or PBS was administered intraperitoneally from days 15 to 21.

RESULTS

Histologically, modified Mankin score of the OA flare was significantly higher than that of OA (7.0 [1.8] vs. 3.3 [1.3], P < 0.05), and a larger number of mast cells was observed in OA flare than in OA (34.5 [6.3]/mm² vs. 27.2 [2.3]/mm², P < 0.05) on day 22. OA flare also showed acute exacerbation of pain and increased gene expression of pro-inflammatory cytokines and aggrecanase compared with OA. Administration of tranilast to OA flare-up provoked significant improvements in term of histological changes, pain, and gene expression at day 22.

CONCLUSION

Our novel model possibly mimics OA flare conditions, which may open a new strategy of disease-modifying treatment for OA, focused on controlling the multiple functions of mast cells.

Expression of Substance P and Nerve Growth Factor in Degenerative Long Head of Biceps Tendon in Patients with Painful Rotator Cuff Tear

Purpose

Degenerative long head of biceps tendon (LHBT) has been recognized as a notable pain source in patients with rotator cuff tear (RCT). Tenotomy or tenodesis of LHBT is frequently indicated together with arthroscopic rotator cuff repair (ARCR) aiming for complete pain relief; however, it has not been fully investigated whether resected LHBT is really a source of pain. The purpose of this study was to investigate expression levels of pain-associated mediators in LHBT and its association with preoperative pain profiles.

Methods

Twenty-seven RCT patients who underwent ARCR with LHBT resection were included. Each LHBT was resected due to its abnormal arthroscopic findings including tenosynovitis, hypertrophy, and partial tear. Worst macroscopic lesion of the LHBT was obtained, and expression levels of substance P (SP) and nerve growth factor (NGF) were evaluated using enzyme-linked immunosorbent assay (ELISA). Ten healthy knee flexor tendons were analyzed as non-degenerative samples. Preoperatively, subjective shoulder pain VAS and pain duration were investigated. Conventional LHBT pain provocation tests (Speed, Yergason, O’Brien) were performed. Pressure pain threshold (PPT) of bilateral LHBT on the groove was recorded.

Results

Levels of SP and NGF expression were significantly higher compared with non-degenerative tendons (P<0.01). Shoulder pain VAS and pain duration were not directly associated with SP and NGF expression level. Patients with positive O’Brien test expressed greater SP than negative patients (P=0.001). Significant negative correlation between the PPT ratio (ipsilateral/contralateral) and SP expression level was observed (r=−0.453, P=0.034).

Conclusion

Greater expression of SP and NGF in degenerative LHBT supported our hypothesis that it would be a pain source in RCT patients. SP was likely to be expressed highly in patients with localized pressure pain hypersensitivity and positive O’Brien test (ie, altered mechanistic pain profile of LHBT), which may help when considering simultaneous LHBT resection during ARCR.

Clinical Registration

UMIN000023943.

Stimuli-Sensitive Nanotherapies for the Treatment of Osteoarthritis

Osteoarthritis (OA) is a common chronic inflammatory disease in the joints. It is one of the leading causes of disability with increasing morbidity, which has become one of the serious clinical issues. Current treatments would only provide temporary relief due to the lack of early diagnosis and effective therapy, and thus the replacement of joints may be needed when the OA deteriorates. Although the intra-articular injection and oral administration of drugs are helpful for OA treatment, they are suffering from systemic toxicity, short retention time in joint, and insufficient bioavailability. Nanomedicine is potential to improve the drug delivery efficiency and targeting ability. In this focused progress review, the particle-based drug loading systems that can achieve targeted and triggered release are summarized. Stimuli-responsive nanocarriers that are sensitive to endogenous microenvironmental signals such as reactive oxygen species, enzymes, pH, and temperature, as well as external stimuli such as light for OA therapy are introduced in this review. Furthermore, the nanocarriers associated with targeted therapy and imaging for OA treatment are summarized. The potential applications of nanotherapies for OA treatment are finally discussed.

Nerve Growth Factor-Targeted Molecular Theranostics Based on Molybdenum Disulfide Nanosheet-Coated Gold Nanorods (MoS2-AuNR) for Osteoarthritis Pain

Osteoarthritis (OA) is a leading cause of chronic pain in the elderly worldwide. Yet current diagnosis and therapy for OA pain are subjective and nonspecific with significant adverse effects. Here, we introduced a theranostic nanoprobe based on molybdenum disulfide nanosheet-coated gold nanorods (MoS₂-AuNR) targeting never growth factor (NGF), a key player in pain sensation, for photoacoustic pain imaging and near-infrared (NIR) imaging-guided photothermal analgesic therapy. MoS₂ coating significantly improved the photoacoustic and photothermal performance of AuNR. Functionalization of MoS₂-AuNR nanoprobes by conjugating with NGF antibody enabled active targeting on painful OA knees in a surgical OA murine model. We observed that our functional nanoprobes accumulated in the OA knee rather than the contralateral intact one, and the amount was correlated with the severity of mechanical allodynia in our mouse model. Under imaging guidance, NIR-excited photothermal therapy could mitigate mechanical allodynia and walking imbalance behavior for both subacute and chronic stages of OA in a preclinical setting. This molecular theranostic approach enabled us to specifically localize the source of OA pain and efficiently block peripheral pain transmission.

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.

The Effectiveness of Anti-Nerve Growth Factor Monoclonal Antibodies in the Management of Pain in Osteoarthritis of the Hip and Knee: A PRISMA Systematic Review and Meta-Analysis

OBJECTIVE

To conduct a systematic review and meta-analysis of the efficacy of anti-nerve growth factor (NGF) monoclonal antibodies in osteoarthritis pain (hip and knee).

DESIGN

Grade the evidence for anti-NGF use.

METHODS

An interdisciplinary work group conducted a literature search for anti-NGF use in osteoarthritis. The systematic review was performed in accordance with methods described by the Cochrane collaboration. General inclusion criteria included all osteoarthritis trials studying any monoclonal anti-NGF antibody at any dose/phase. Excluded studies were those where participants received NSAIDs or analgesics other than anti-NGF antibodies. The Jadad Scale score was used to assess the quality of the included studies.

RESULTS

Thirteen studies were included in the analysis, involving 8145 participants with a diagnosis of hip and/or knee osteoarthritis. Anti-NGF antibody treatment was associated with a significant improvement in all Western Ontario and McMaster Universities Arthritis Index (WOMAC) indices when compared to placebo. These agents were not associated with a significantly increased incidence of serious adverse events but were associated with significant increases in therapy discontinuation due to adverse events or side effects (e.g., peripheral neuropathy).

CONCLUSIONS

Future randomized clinical trials are needed to characterize the overall risk-to-benefit ratio of anti-NGF antibodies in managing pain associated with OA, particularly with long-term use, in order to verify their efficacy and safety in clinical practice.

Clinical Outcomes of Tanezumab With Different Dosages for Patient With Osteoarthritis: Network Meta-Analysis

Background: Osteoarthritis (OA) high disability rate will increase as people getting older, and is the most prevalent form of arthritis in the future. This study identified the clinical effects of optimum doses of tanezumab for patients with OA. Method: Three electronic databases were searched up until January 15, 2021. The mean difference (MD) or odds ratio (OR) was considered an effect measure. The design-by-treatment interaction model was adopted for network meta-analyses. Analyses were conducted using WinBUGS 1.4.3 and R 4.0.5 software. Results: nine publications with 10 studies were included. Compared with placebo in network meta-analysis, except the outcomes of Western Ontario and McMaster Universities Osteoarthritis (WOMAC) stiffness subscale and joints replaced, all dosages of tanezumab in the other effectiveness outcome were superior to placebo, and the difference was statistically significant. However, there was no statistical difference among all different doses of tanezumab. Compared with placebo, except the outcomes of adverse events (AEs) and AEs of abnormal peripheral sensation, all different dosages of tanezumab weren't superior to placebo in the other effectiveness outcome, and the difference was statistically significant. The 10 mg of tanezumab with highest SUCRA had the best effect, but it was associated with a higher safety event. Compared with placebo, except the outcomes of WOMAC stiffness subscale and joints replaced, all dosages of tanezumab in the other effectiveness outcome were superior to placebo, and the difference was statistically significant. Compared with placebo, except for the outcomes of AEs and AEs of abnormal peripheral sensation, all dosages of tanezumab in the other effectiveness outcome were superior to placebo, and the difference was statistically significant. Other direct comparisons showed no statistical difference. Conclusion: This study recommended that clinicians should give priority to the treatment of OA patients with a low dose of 2.5 mg according to the patient's condition and actual situation. If the effect using tanezumab with 2.5 mg is not satisfactory, the increase up to 10 mg should be carefully pondered, because of a more unbalanced risk/benefit ratio.

Pharmacokinetics and Immunogenicity of Frunevetmab in Osteoarthritic Cats Following Intravenous and Subcutaneous Administration

Osteoarthritis and other degenerative joint diseases are common causes of chronic pain in cats. Frunevetmab is a felinized monoclonal antibody that binds to nerve growth factor (NGF) and provides relief from pain by blocking the receptor-mediated signaling cascade induced by NGF. Results from three studies were combined to provide an overview of frunevetmab pharmacokinetics (PK) and immunogenicity. The objective of the first study was to establish the pharmacokinetic parameters resulting from intravenous (IV) and subcutaneous (SC) administration of frunevetmab to the feline patient population at 3 mg/kg. Ten adult cats with naturally-occurring osteoarthritis were administered frunevetmab in a crossover design at 28 day intervals. Non-compartmental pharmacokinetic analysis of the plasma concentration-time data showed that the half-life was 10.1 ± 1.9 days after IV dosing and the SC bioavailability was 60.3 ± 15.8% with maximum drug levels observed at 3-7 days after dosing. Plasma samples were collected at ~28 days after dosing during two field safety and effectiveness studies of cats with degenerative joint disease. The doses ranged from 1.0 to 2.8 mg/kg; 2 or 3 doses were administered either SC/IV, SC/SC, or SC/SC/SC. The data from these studies along with the data from the laboratory pharmacokinetic study were analyzed using non-linear mixed-effects (NLME) modeling. The model closely predicted the trough concentrations from the two field studies, including the IV treatment in the pilot field study. The trough concentrations were predicted to be close to steady-state after 2 doses. A second objective was to determine the incidence and clinical relevance of frunevetmab immunogenicity. A three-tier anti-drug antibody assay (screen, confirm, titer) was developed and validated. Immunogenicity was assessed in 259 frunevetmab-treated animals enrolled in the two field studies. Only 4 of these animals (1.5%) appeared to develop immunogenicity to frunevetmab. None of the four exhibited adverse events attributed to immunogenicity and no impact on drug levels or efficacy was observed in three of the animals. In the placebo animals, 2.3% (3/131) appeared to develop treatment-emergent immunogenicity. Overall, frunevetmab administration resulted in a very low incidence of treatment-emergent immunogenicity with no safety findings and minimal effect on drug exposure and efficacy.

Increased nerve growth factor expression in the synovial tissues of patients with rotator cuff tears

Background

Rotator cuff tears (RCTs) are often associated with severe shoulder pain. Non-steroidal anti-inflammatory drugs, not recommended for long-term use, do not effectively manage RCT-induced pain, resulting in reduced quality of life. To improve management, a better understanding of the fundamental properties of RCT pain is needed. Here, we aimed to compare the expression levels of nerve growth factor (NGF) and cyclooxygenase-2 (COX-2) mRNA in the synovial tissues of patients with RCT-induced pain and patients with non-painful recurrent shoulder dislocation (RSD).

Methods

The study included 32 patients with RCT who underwent arthroscopic rotator cuff repair and 28 patients with non-painful RSD who underwent arthroscopic Bankart repair. Synovial tissue samples were harvested from subacromial bursa and rotator interval of RCT patients and from the rotator interval of RSD patients. Samples were analyzed quantitatively expression levels for NGF and COX2 mRNA and NGF protein.

Results

NGF mRNA and protein levels were significantly higher in the rotator interval of RCT patients than in the rotator interval of RSD patients (p = 0.0017, p = 0.012, respectively), while COX2 mRNA levels did not differ significantly between the two patient groups. In RCT patients, COX2 mRNA was more highly expressed in the rotator interval than in the subacromial bursa (p = 0.038), whereas the mRNA and protein levels of NGF did not differ between the two tissues. The expression of NGF mRNA in the synovium of the rotator interval was significantly correlated with the numeric rating scale of pain (ρ = 0.38, p = 0.004).

Conclusion

NGF mRNA and protein levels were elevated in patients with painful RCT compared with those in patients with non-painful RSD, whereas COX-2 levels were comparable in the two patient groups. These findings provide insights into novel potential strategies for clinical management of RCT.

Efficacy and Safety of an Anti-nerve Growth Factor Antibody (Frunevetmab) for the Treatment of Degenerative Joint Disease-Associated Chronic Pain in Cats: A Multisite Pilot Field Study

Background: Pain management for cats with degenerative joint disease (DJD) remains a critical unmet need. Recent work has shown promise for a feline-specific anti-nerve growth factor monoclonal antibody (frunevetmab) to deliver safe and effective pain management. Our objectives were to evaluate the efficacy and safety of frunevetmab administered twice using two administration routes (subcutaneous and intravenous) compared to placebo. Methods: This was a randomized placebo-controlled, double-masked study. After a week-long pain and activity baseline, 126 cats were randomized to receive injections of frunevetmab (IV then SC; n = 42 or SC then SC; n = 43) or placebo (IV then SC; n = 41) on Days 0 and 28. Owners completed questionnaires on Days 14, 28, 42, and 56. Accelerometry data were collected continuously throughout. Results: Owner questionnaire results showed significant improvement in frunevetmab-treated cats [compared to placebo; (p < 0.05)] at Days 42 and 56; no difference was found between routes of administration for frunevetmab. All groups had decreased objectively measured weekly activity from baseline; frunevetmab-treated cats had a mean decrease of 0.9%, while placebo-treated cats had a mean decrease of 9.3%. Treatments were generally well-tolerated. The majority of adverse events included dermatitis/alopecia related to activity-monitor collars; these occurred in a higher percentage of frunevetmab, compared to placebo, treated cats. Conclusions and Clinical Relevance: Treatment with frunevetmab provided improvements in owner ratings of mobility over treatment with placebo; these results were supported by objectively measured accelerometry. Frunevetmab has the potential to address a critical gap in the treatment of chronic pain in cats.

General Safety and Tolerability of Subcutaneous Tanezumab for Osteoarthritis: A Pooled Analysis of 3 Randomized, Placebo-Controlled Trials

Objective

This pooled analysis of 3 randomized, placebo‐controlled trials (16–24 week treatment and 8–24 week follow‐up) assessed safety of subcutaneous tanezumab (2.5–10 mg every 8 weeks) in 1,840 patients with hip or knee osteoarthritis.

Methods

Overall treatment‐emergent adverse events (TEAEs) and TEAEs of abnormal peripheral sensation (APS) were prospectively assessed in 3 trials. Joint safety events (primary osteonecrosis, rapidly progressive osteoarthritis [RPOA], subchondral insufficiency fracture, and pathologic fracture; adjudicated by an independent expert committee) and TEAEs potentially associated with sympathetic neuropathy were prospectively assessed in 2 trials.

Results

During the treatment period, overall TEAE rates were 51.7% for placebo and 39.5–54.8% for tanezumab 2.5–10 mg; treatment discontinuation rates were 2.0% for placebo and 0–1.3% for tanezumab. Rates of composite joint safety events (predominantly RPOA type 1) over the treatment plus follow‐up period were 0% for placebo and 0.5–3.2% for tanezumab 2.5–5 mg (5 mg was statistically greater than placebo); total joint replacement rates with tanezumab (5.9–7.0%) were not significantly different from placebo (4.5%). Rates of TEAEs of APS (predominantly paresthesia and hypoesthesia) were 2.2% for placebo and 3.2–12.8% for tanezumab 2.5–10 mg. Rates of TEAEs potentially associated with sympathetic neuropathy (predominantly bradycardia and orthostatic hypotension) were 0.8% for placebo and 0.5–2.8% for tanezumab 2.5–5 mg (exposure‐adjusted rates were not significantly different from placebo).

Conclusion

Tanezumab was generally well tolerated. TEAEs of APS (mostly mild and transient) and joint safety events were infrequent but more common with tanezumab than placebo. A tanezumab dose of 2.5 mg demonstrated a more favorable safety profile than higher doses.

Osteoarthritis: From upcoming treatments to treatments yet to come

Osteoarthritis affects hundreds of millions of people worldwide, and its prevalence is constantly increasing. While there is currently no treatment that can alter the course of the disease, promising therapeutic strategies and novel targets are being investigated. Innovative cell therapies are already reaching clinical trials, and recent progress in our understanding of the disease is opening new routes for gene therapy. In the long term, the development of new biofabrication tools, such as 3D bioprinting, may pave the way for personalized mini-joint models that could be used to screen drugs and to personalize treatments. This review provides an overview of the most promising therapeutic approaches in the field of osteoarthritis, from upcoming treatments to those that are yet to be discovered.

Subcutaneous tanezumab for osteoarthritis: Is the early improvement in pain and function meaningful and sustained?

Background

To evaluate if early improvements in pain and function with subcutaneous tanezumab are meaningful and sustained over 24 weeks.

Methods

Patients with moderate‐to‐severe osteoarthritis (hip or knee) in Europe and Japan were randomized to placebo, tanezumab 2.5 mg or tanezumab 5 mg (baseline, Week 8 and Week 16). Outcomes included: average daily index joint pain score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) subscales, rescue medication use, WOMAC responders (within‐patient ≥30% reduction in WOMAC Pain or Physical Function), Outcome Measures in Rheumatology‐Osteoarthritis Research Society International (OMERACT‐OARSI) responders (within‐patient) and Patient‐reported Treatment Impact Assessment‐Modified questionnaire.

Results

Patients received placebo (n = 282), tanezumab 2.5 mg (n = 283) or tanezumab 5 mg (n = 284). Changes from baseline in average daily index joint pain (within the first week) and WOMAC subscales (Week 2 through Week 24) were greater for each tanezumab group versus placebo (least squares [LS] mean, unadjusted p ≤ .05). Rescue medication use (days/week) was lower for each tanezumab group versus placebo from Week 2 through Week 12 (LS mean, unadjusted p ≤ .05) but not at Week 16 or 24. A higher proportion of each tanezumab group than placebo achieved ≥30% reduction from baseline in WOMAC Pain or Physical Function, or OMERACT‐OARSI response (Week 2 through Week 24, unadjusted p ≤ .05), or were satisfied with treatment at Week 24 (unadjusted p ≤ .05).

Conclusions

Subcutaneous tanezumab, compared with placebo, reduced pain within the first week, and pain and function were improved throughout 24 weeks. The proportions of responders and patients satisfied were higher with tanezumab than placebo.

ClinicalTrials.gov:NCT02709486.

Significance

This exploratory analysis of data from a placebo‐controlled, Phase 3 study of patients with moderate‐to‐severe osteoarthritis of the hip or knee for whom standard analgesics were not effective or could not be taken, found that onset of efficacy of subcutaneous tanezumab was within the first week, and efficacy was maintained through the 24‐week treatment period. Tanezumab was effective in those patients with the most radiologically severe osteoarthritis.

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.

Peripheral pain mechanisms in osteoarthritis

There is a well-established historical observation that structural joint damage by plain X-ray correlates poorly with symptomatic disease in osteoarthritis (OA). This is often attributed to the inability to visualise soft-tissue pathology within the joint and the recognition of heterogeneous patient factors that drive central pain sensitisation. A major issue is the relative paucity of mechanistic studies in which molecular pathogenesis of pain is interrogated in relation to tissue pathology. Nonetheless, in recent years, three broad approaches have been deployed to attempt to address this: correlative clinical studies of peripheral and central pain outcomes using magnetic resonance imaging, where soft-tissue processes can be visualised; molecular studies on tissue from patients with OA; and careful molecular interrogation of preclinical models of OA across the disease time course. Studies have taken advantage of established clinical molecular targets such as nerve growth factor. Not only is the regulation of nerve growth factor within the joint being used to explore the relationship between tissue pathology and the origins of pain in OA, but it also provides a core model on which other molecules present within the joint can modulate the pain response. In this narrative review, how molecular and pathological tissue change relates to joint pain in OA will be discussed. Finally, a model for how tissue damage may lead to pain over the disease course will be proposed.

Quantifying noxious-evoked baseline sensitivity in neonates to optimise analgesic trials

Despite the high burden of pain experienced by hospitalised neonates, there are few analgesics with proven efficacy. Testing analgesics in neonates is experimentally and ethically challenging and minimising the number of neonates required to demonstrate efficacy is essential. EEG (electroencephalography)-derived measures of noxious-evoked brain activity can be used to assess analgesic efficacy; however, as variability exists in neonate's responses to painful procedures, large sample sizes are often required. Here, we present an experimental paradigm to account for individual differences in noxious-evoked baseline sensitivity which can be used to improve the design of analgesic trials in neonates. The paradigm is developed and tested across four observational studies using clinical, experimental, and simulated data (92 neonates). We provide evidence of the efficacy of gentle brushing and paracetamol, substantiating the need for randomised controlled trials of these interventions. This work provides an important step towards safe, cost-effective clinical trials of analgesics in neonates.

Estrogen Regulation of the Expression of Pain Factor NGF in Rat Chondrocytes

OBJECTIVE

Pain is the main symptom of osteoarthritis (OA). Nerve growth factor (NGF) plays a crucial role in the generation of OA pain. And estrogen-alone used resulted in a sustained joint pain reduction in postmenopausal women. So we aim to find whether estrogen alters chondrocytes' NGF level, affecting OA pain.

METHODS

Primary chondrocytes and cartilage explants isolated from Sprague Dawley rat knees were cultured with physiological concentrations of estrogen (17β-Estradiol ≥ 98%, E2), Estrogen Receptor α (ERα) inhibitor and stimulants. Then, chondrocytes NGF mRNA expression and protein release were analyzed by a quantitative real-time polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA) respectively. Additionally, cultures were pre-incubated with MEK-ERK inhibitor to identify the signaling pathway that estrogen alters NGF mRNA and protein levels.

RESULTS

We found that chondrocytes NGF expression and release were decreased by E2. E2 also reduced chondrocytes IL-1β-stimulated or TGF-β1-stimulated NGF expression. Phosphorylated extracellular signal-regulated kinasep1/2 (p-ERK1/2) signals were detected stronger than the control group by Western Blotting (WB). When we cultured chondrocytes with PD98059 (MEK-ERK inhibitor, PD), NGF mRNA expression was added to 1.41Ct (2.07±0.1 fold).

CONCLUSION

We showed that E2 reduces chondrocytes NGF expression significantly, even after stimulation by TGF-β1 or IL-1β. MEK-ERK signaling is involved in this process.

Subchondral bone microenvironment in osteoarthritis and pain

Osteoarthritis comprises several joint disorders characterized by articular cartilage degeneration and persistent pain, causing disability and economic burden. The incidence of osteoarthritis is rapidly increasing worldwide due to aging and obesity trends. Basic and clinical research on osteoarthritis has been carried out for decades, but many questions remain unanswered. The exact role of subchondral bone during the initiation and progression osteoarthritis remains unclear. Accumulating evidence shows that subchondral bone lesions, including bone marrow edema and angiogenesis, develop earlier than cartilage degeneration. Clinical interventions targeting subchondral bone have shown therapeutic potential, while others targeting cartilage have yielded disappointing results. Abnormal subchondral bone remodeling, angiogenesis and sensory nerve innervation contribute directly or indirectly to cartilage destruction and pain. This review is about bone-cartilage crosstalk, the subchondral microenvironment and the critical role of both in osteoarthritis progression. It also provides an update on the pathogenesis of and interventions for osteoarthritis and future research targeting subchondral bone.

Local Administration of Low-Dose Nerve Growth Factor Antibody Reduced Pain in a Rat Osteoarthritis Model

Systemic injection of a nerve growth factor (NGF) antibody has been proven to have a significant relevance in relieving osteoarthritis (OA) pain, while its adverse effects remain a safety concern for patients. A local low-dose injection is thought to minimize adverse effects. In this study, OA was induced in an 8-week-old male Sprague–Dawley (SD) rat joint by monoiodoacetate (MIA) injection for 2 weeks, and the effect of weekly injections of low-dose (1, 10, and 100 µg) NGF antibody or saline (control) was evaluated. Behavioral tests were performed, and at the end of week 6, all rats were sacrificed and their knee joints were collected for macroscopic and histological evaluations. Results showed that 100 µg NGF antibody injection relieved pain in OA rats, as evidenced from improved weight-bearing performance but not allodynia. In contrast, no significant differences were observed in macroscopic and histological scores between rats from different groups, demonstrating that intra-articular treatment does not worsen OA progression. These results suggest that local administration yielded a low effective NGF antibody dose that may serve as an alternative approach to systemic injection for the treatment of patients with OA.

Parathyroid hormone attenuates osteoarthritis pain by remodeling subchondral bone in mice

Osteoarthritis, a highly prevalent degenerative joint disorder, is characterized by joint pain and disability. Available treatments fail to modify osteoarthritis progression and decrease joint pain effectively. Here, we show that intermittent parathyroid hormone (iPTH) attenuates osteoarthritis pain by inhibiting subchondral sensory innervation, subchondral bone deterioration, and articular cartilage degeneration in a destabilized medial meniscus (DMM) mouse model. We found that subchondral sensory innervation for osteoarthritis pain was significantly decreased in PTH-treated DMM mice compared with vehicle-treated DMM mice. In parallel, deterioration of subchondral bone microarchitecture in DMM mice was attenuated by iPTH treatment. Increased level of prostaglandin E2 in subchondral bone of DMM mice was reduced by iPTH treatment. Furthermore, uncoupled subchondral bone remodeling caused by increased transforming growth factor β signaling was regulated by PTH-induced endocytosis of the PTH type 1 receptor-transforming growth factor β type 2 receptor complex. Notably, iPTH improved subchondral bone microarchitecture and decreased level of prostaglandin E2 and sensory innervation of subchondral bone in DMM mice by acting specifically through PTH type 1 receptor in Nestin+ mesenchymal stromal cells. Thus, iPTH could be a potential disease-modifying therapy for osteoarthritis.

Management of Knee Osteoarthritis: What Internists Need to Know

Knee osteoarthritis (OA) is a common and morbid condition. No disease-modifying therapies exist; hence the goals of current treatment are to palliate pain and to retain function. OA is significantly influenced by the placebo effect. Nonpharmacologic interventions are essential and have been shown to improve outcomes. Canes, unloading braces, and therapeutic heating/cooling may be valuable. Pharmacotherapy options include topical and oral nonsteroidal anti-inflammatory drugs, duloxetine, and periodic intra-articular glucocorticoids and hyaluronans. Opioids, intra-articular stem cells, and platelet-rich plasma are not recommended. Novel targets such as nerve growth factor are under investigation and may be approved soon for OA pain.

Diagnosis and Treatment of Hip and Knee Osteoarthritis: A Review

Importance

Osteoarthritis (OA) is the most common joint disease, affecting an estimated more than 240 million people worldwide, including an estimated more than 32 million in the US. Osteoarthritis is the most frequent reason for activity limitation in adults. This Review focuses on hip and knee OA.

Observations

Osteoarthritis can involve almost any joint but typically affects the hands, knees, hips, and feet. It is characterized by pathologic changes in cartilage, bone, synovium, ligament, muscle, and periarticular fat, leading to joint dysfunction, pain, stiffness, functional limitation, and loss of valued activities, such as walking for exercise and dancing. Risk factors include age (33% of individuals older than 75 years have symptomatic and radiographic knee OA), female sex, obesity, genetics, and major joint injury. Persons with OA have more comorbidities and are more sedentary than those without OA. The reduced physical activity leads to a 20% higher age-adjusted mortality. Several physical examination findings are useful diagnostically, including bony enlargement in knee OA and pain elicited with internal hip rotation in hip OA. Radiographic indicators include marginal osteophytes and joint space narrowing. The cornerstones of OA management include exercises, weight loss if appropriate, and education-complemented by topical or oral nonsteroidal anti-inflammatory drugs (NSAIDs) in those without contraindications. Intra-articular steroid injections provide short-term pain relief and duloxetine has demonstrated efficacy. Opiates should be avoided. Clinical trials have shown promising results for compounds that arrest structural progression (eg, cathepsin K inhibitors, Wnt inhibitors, anabolic growth factors) or reduce OA pain (eg, nerve growth factor inhibitors). Persons with advanced symptoms and structural damage are candidates for total joint replacement. Racial and ethnic disparities persist in the use and outcomes of joint replacement.

Conclusions and Relevance

Hip and knee OA are highly prevalent and disabling. Education, exercise and weight loss are cornerstones of management, complemented by NSAIDs (for patients who are candidates), corticosteroid injections, and several adjunctive medications. For persons with advanced symptoms and structural damage, total joint replacement effectively relieves pain.

Ultra-purified alginate gel implantation decreases inflammatory cytokine levels, prevents intervertebral disc degeneration, and reduces acute pain after discectomy

Lumbar intervertebral disc (IVD) herniation causes severe low back pain (LBP), which results in substantial financial and emotional strains. Despite the effectiveness of discectomy, there is no existing treatment for post-operative LBP induced by progressive IVD degeneration. Two key factors of LBP are intradiscal inflammation, indicated by tumour necrosis factor alpha (TNF-α) and interleukin-6 (IL-6), and sensory nerve ingrowth into the inner layer of the annulus fibrosus, triggered by nerve growth factor/high-affinity tyrosine kinase A (TrkA) signalling. In an animal models of discectomy, the bioresorbable ultra-purified alginate (UPAL) gel with an extremely low-toxicity has been effective in acellular tissue repair. We aimed to investigate whether UPAL gel can alleviate LBP using a rat nucleus pulposus (NP) punch model and a rabbit NP aspirate model. In both models, we assessed TNF-α and IL-6 production and TrkA expression within the IVD by immunohistochemistry. Further, histological analysis and behavioural nociception assay were conducted in the rat model. UPAL gel implantation suppressed TNF-α and IL-6 production, downregulated TrkA expression, inhibited IVD degeneration, and reduced nociceptive behaviour. Our results suggest the potential of UPAL gel implantation as an innovative treatment for IVD herniation by reducing LBP and preventing IVD degeneration after discectomy.