Nerve Growth Factor Antibodies Research Articles

[Effect of nerve growth factor on elderly degenerative knee osteoarthritis pain].

To explore effect of nerve growth factor (NGF) antibody on knee osteoarthritis (KOA) pain model was evaluated by in vitro model. Thirty male SPF rats aged 28-week-old were divided into blank group (10 rats with anesthesia only). The other 20 rats were with monoiodoacetate (MIA) on the right knee joint to establish pain model of OA, and were randomly divided into control group (injected intraperitoneal injection of normal saline) and treatment group (injected anti-NGF) intraperitoneal after successful modeling, and 10 rats in each group. All rats were received retrograde injection of fluorogold (FG) into the right knee joint. Gait was assessed using catwalk gait analysis system before treatment, 1 and 2 weeks after treatment. Three weeks after treatment, right dorsal root ganglia (DRG) were excised on L4-L6 level, immunostained for calcitonin gene-related peptide (CGRP), and the number of DRGS was counted. In terms of gait analysis using cat track system, duty cycle, swing speed and print area ratio in control and treatment group were significantly reduced compared with blank group (P<0.05). Compared with control group, duty cycle and swing speed of treatment group were significantly improved (P<0.05), and there was no significant difference in print area ratio between treatment group and blank group (P>0.05). The number of FG-labeled DRG neurons in control group was significantly higher than that in treatment group and blank group (P<0.05). The expression of CGRP in control group was up-regulated, and differences were statistically significant compared with treatment group (P<0.05). Intraperitoneal injection of anti-NGF antibody inhibited gait injury and upregulation of CGRP in DRG neurons. The results suggest that anti-nerve growth factor therapy may be of value in treating knee pain. NGF may be an important target for the treatment of knee OA pain.

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.

Efficacy and Safety of Anti-Nerve Growth Factor Antibody Therapy for Hip and Knee Osteoarthritis: A Meta-analysis.

Background:The efficacy and safety of anti–nerve growth factor (NGF) antibody therapy used for osteoarthritis (OA) pain are controversial.Purpose:To evaluate the efficacy and safety of anti-NGF antibody therapy via a meta-analysis of randomized controlled trials (RCTs).Study Design:Systematic review; Level of evidence, 1.Methods:PubMed, the Cochrane Central Register of Controlled Trials, Embase, and the Web of Science databases were searched for RCTs assessing anti-NGF antibody treatments for hip and knee OA. A total of 623 records were retrieved from the databases. A random-effects model was used to assess primary and secondary outcomes. Bias was assessed using the Cochrane Collaboration tool, funnel plots, and the Egger test. Subgroup analyses were used to assess the efficacy and safety of the independent variables. Sensitivity analysis was conducted to evaluate the effectiveness of tanezumab and the effectiveness of anti-NGF antibodies compared to active comparator drugs. We present the effects of dose, administration mode, and treatment duration on the efficacy and safety of anti-NGF antibody therapy.Results:There were 19 RCTs included in our meta-analysis. Anti-NGF antibody treatment showed significant improvements on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) for pain, physical function, and stiffness as well as on a patient global assessment (PGA). The overall standardized mean differences were as follows: WOMAC pain (–0.31 [95% CI, –0.36 to –0.26]; Z = 11.75; P < .001; I 2 = 38%), WOMAC physical function (−0.36 [95% CI, –0.41 to –0.30]; Z = 12.67; P < .001; I 2 = 44%), WOMAC stiffness (–3.59 [95% CI, –4.87 to –2.30]; Z = 5.47; P < .001; I 2 = 98%), and PGA (−0.28 [95% CI, –0.34 to –0.22]; Z = 9.39; P < .001; I 2 = 50%). Anti-NGF antibody treatment resulted in a greater incidence of adverse events (risk ratio, 1.09 [95% CI, 1.06 to 1.12]; Z = 5.60; P < .001; I 2 = 0%). The incidence of serious adverse events was similar between the treatment and control groups (risk ratio, 1.15 [95% CI, 0.98 to 1.34]; Z = 1.71; P = .09; I 2 = 0%).Conclusion:Anti-NGF antibody treatment significantly relieved pain and improved function in patients with hip and knee OA. However, no conclusion could be drawn regarding the optimal treatment plan for anti-NGF antibodies when all 3 variables (dose, administration mode, and treatment duration) were combined in the analyses.

Population pharmacokinetics of tanezumab following intravenous or subcutaneous administration to patients with osteoarthritis or chronic low back pain.

Describe population pharmacokinetics of intravenous (IV) and subcutaneous (SC) tanezumab across Phase 2b/3 studies of osteoarthritis and chronic low back pain. Data from 10 studies of IV or SC tanezumab (2.5-20 mg every 8 wk for up to 56 wk) were included in a multistep analysis. In Step 1, a 2-compartment model with linear and nonlinear 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). SC bioavailability was estimated at 62-76%. The key disposition parameters CL, Vc , Vp and KM were estimated to be 0.133 L d-1 , 2.6 L, 1.77 L and 31.2 μg L-1 , respectively. Plasma tanezumab concentration was predicted to reach Cmax 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 wk). Exposure of a typical patient was similar between IV and SC for the second part of the dosing interval (wk 4-8). Covariates selected on the absorption parameters were weight, 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%). Our model adequately described plasma tanezumab concentration vs. time following IV or SC administration. Weight was the most influential covariate with respect to absorption of tanezumab in comparison to patient population (osteoarthritis and chronic low back pain) or other demographics. There was no clinically relevant effect of baseline NGF or TE ADA on tanezumab PK.

DeepNeurite™: Identification of neurites from non‐specific binding of fluorescence probes through deep learning

The nervous system plays an important role in human health and disease, and the unique morphologies of the neurons underlie its ability to interface with tissues and organs throughout the entire body. In vitro, neurons can be grown alone or with other cell types to gain insight into how they communicate with other cell types in a more controlled experimental setup. To measure neuron growth and to study neuronal connectivity in vitro, neurite identification is an essential readout. However, non-specific binding of fluorescence probes, a fundamental issue of fluorescence imaging, impairs neurite identification through conventional mathematical morphology-based methods, especially in neuron and other cell type co-culture imaging conditions. Here, we utilized a deep learning algorithm and developed a computational tool called DeepNeurite™, to overcome this challenge. We demonstrated that DeepNeurite™ can accurately identify neurite structure in images acquired from microfluidic compartmentalized chambers where neurons were co-cultured, such as with a human prostate cancer cell line, PC3. We further validated that the model can be generalized to handle a direct co-culture in which neurons and lung cancer cells (DMS273) are grown intermingled in the same well. Using this method, we observed more neurite growth into PC3 containing chambers in microfluidic compartmentalized chambers, which could be blocked by an NGF antibody. Finally, we applied DeepNeurite™ coupled with functional calcium imaging to study the communication of primary sensory neurons and cancer cells. We showed that the cancer cells closer to neurites exhibit greater calcium activity in response to neuronal stimulation. This method opens lots of opportunities to study the effect of neurons on various other cell types. This model could further tackle the off-target labeling of the fluorescence probe in other subcellular structures or cell types.

Commentary: The Efficacy of Nerve Growth Factor Antibody for the Treatment of Osteoarthritis Pain and Chronic Low-Back Pain: A Meta-analysis.

Commentary: The Efficacy of Nerve Growth Factor Antibody for the Treatment of Osteoarthritis Pain and Chronic Low-Back Pain: A Meta-analysis.

Pooled analysis of tanezumab efficacy in osteoarthritis of different radiographic severities

Purpose: Tanezumab, a nerve growth factor antibody, is being developed to relieve the signs and symptoms of osteoarthritis (OA). This subgroup analysis explored the efficacy of subcutaneous tanezumab in patients with OA of different radiographic severities.

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.

Targeting nerve growth factor, a new option for treatment of osteoarthritis: a network meta-analysis of comparative efficacy and safety with traditional drugs.

Objective: Osteoarthritis (OA) is the most common joint disease and leading cause of pain and disability in the elderly population. Most guidelines recommend the use of non-steroidal anti-inflammatory drugs (NSAIDs) and opioids for the non-operative treatment of OA. Monoclonal nerve growth factor (NGF) antibodies are new drugs with the potential to provide pain relief and functional improvement in OA. We compared the efficacy (pain reduction and functional improvement), and safety of monoclonal NGF antibodies with NSAIDs and opioids in the treatment of OA with a Bayesian network meta-analysis.Results: 38 articles, comprising 41 trials and 20489 patients with OA were included. Overall from the network meta-analysis, anti-NGFs were the most effective drugs for pain relief (Standardized Mean Difference or SMD compared with placebo 4.25, 95% CI 2.87 to 5.63, Surface Under the Cumulative RAnking curve or SUCRA=93.7%) and for functional improvement (SMD 4.90, 95% CI 3.46 to 6.33, SUCRA=98.3%). Although anti-NGFs were associated with higher risk of peripheral sensation abnormality (paresthesia and pruritus), they were not associated with higher risk of other AEs (headaches and nausea) or with higher withdrawal rates related to AEs.Conclusions: Monoclonal NGF antibodies provide significantly greater pain relief and functional improvement in OA compared to NSAIDs and opioids. Monoclonal NGF antibodies are not associated with severe AEs. More studies are needed to confirm these findings.Methods: PubMed, CNKI, Web of Science, Scopus, Embase and Cochrane Library databases were searched for relevant studies (OA treated with anti-NGFs, opioids, selective COX-2 inhibitors or NSAIDs) published between January 1999 to January 2020. Bayesian network and conventional meta-analyses were conducted. Pain relief, functional improvement and AEs were assessed.

Acid-sensing Ion Channel 3 Overexpression in Incisions Regulated by Nerve Growth Factor Participates in Postoperative Nociception in Rats.

Acid-sensing ion channel 3 (ASIC3) upregulation has been reported in dorsal root ganglion neurons after incision and contributes to postoperative nociception. This study hypothesized that upregulation of ASIC3 in incised tissues is induced by nerve growth factor through the phosphoinositide 3-kinase/protein kinase B signaling pathway. A plantar incision model was established in adult male and female Sprague-Dawley rats. ASIC3 was inhibited by APETx2 treatment, small interfering RNA treatment, or ASIC3 knockout. Sciatic nerve ligation was performed to analyze ASIC3 transport. A nerve growth factor antibody and a phosphoinositide 3-kinase inhibitor were used to investigate the mechanism by which nerve growth factor regulates ASIC3 expression. Acid-sensing ion channel 3 inhibition decreased incisional guarding and mechanical nociception. ASIC3 protein levels were increased in skin and muscle 4 h after incision (mean ± SD: 5.4 ± 3.2-fold in skin, n = 6, P = 0.001; 4.3 ± 2.2-fold in muscle, n = 6, P = 0.001). Sciatic nerve ligation revealed bidirectional ASIC3 transport. Nerve growth factor antibody treatment inhibited the expression of ASIC3 (mean ± SD: antibody 2.3 ± 0.8-fold vs. vehicle 4.9 ± 2.4-fold, n = 6, P = 0.036) and phosphorylated protein kinase B (mean ± SD: antibody 0.8 ± 0.3-fold vs. vehicle 1.8 ± 0.8-fold, n = 6, P = 0.010) in incised tissues. Intraplantar injection of nerve growth factor increased the expression of ASIC3 and phosphorylated protein kinase B. ASIC3 expression and incisional pain-related behaviors were inhibited by pretreatment with the phosphoinositide 3-kinase inhibitor LY294002. Acid-sensing ion channel 3 overexpression in incisions contributes to postoperative guarding and mechanical nociception. Bidirectional transport of ASIC3 between incised tissues and dorsal root ganglion neurons occurs through the sciatic nerve. Nerve growth factor regulates ASIC3 expression after plantar incision through the phosphoinositide 3-kinase/protein kinase B signaling pathway.

Pain behaviour assessments by gait and weight bearing in surgically induced osteoarthritis and inflammatory arthritis

Objective. Osteoarthritis (OA) is the most common cause of joint pain. Animal models and relevant assays for measurement of pain-related behaviours are important tools for studies of mechanisms inducing and sustaining pain in OA. The aim of this study was to evaluate two different assessments of weight bearing; stationary and during locomotion, and to explore their feasibility to detect analgesic effects in vivo. Two fundamentally different mouse models of joint arthritis were investigated; surgical transection of the anterior cruciate ligament (ACLT) resulting in destabilization of the joint with subsequent structural deterioration resembling OA, and monoarthritis induced by injection of Complete Freund´s Adjuvant (CFA) into the ankle joint capsule. Design. Mice were subjected to ACLT or CFA injection into the ankle joint. Stationary weight bearing was performed up to twenty weeks after ACLT, and for two weeks after CFA. In addition, mice with CFA-induced monoarthritis were assessed for gait and weight bearing during locomotion, and the effects of an anti-NGF antibody (MEDI578) were tested. End point histopathological analysis was performed in knee joints of ACLT mice, and in mice with ankle joint injection of CFA at eight days after injection. Results. Both the surgical ACLT and CFA-induced monoarthritis reduced stationary weight bearing on the affected paw. The reduction in weight bearing was compensated by all other legs, but differently when stationary compared to during locomotion in the CFA-injected mice. The behavioural effects of ACLT correlated to the structural changes of the joint. In the CFA-induced monoarthritis, showing a massive infiltration of inflammatory cells at 8 days, MEDI578 significantly attenuated the pain-like behaviours. Conclusions. The pain-like behaviour detected is mainly due to inflammation and not to the same degree to structural changes in the joint. Behavioural effects after ACLT were too small for pharmacological evaluation of pain relief. In contrast, the inflammation after CFA injection caused a long-lasting effect on pain-like behaviours such as weight bearing and gait, which could be attenuated by administration of an anti NGF antibody.

An update on targets for treating osteoarthritis pain: NGF and TRPV1.

a)Osteoarthritis (OA) is the most common form of arthritis, and pain is the primary symptom of the disease, yet analgesic options for treating OA pain remain limited. In this review, we aimed to give an update on the current clinical and preclinical studies targeting two pathways that are being investigated for treating OA pain: the nerve growth factor (NGF) pathway and the transient receptor potential vanilloid-1 (TRPV1) pathway. b)Antibodies against NGF, small molecule inhibitors of TrkA, TRPV1 agonists, and TRPV1 antagonists are all in different stages of clinical and pre-clinical testing for the treatment of OA pain. NGF antibodies have shown efficacy in the primary endpoints tested compared to placebo, however, rapidly progressive OA has been consistently observed in a subset of patients and the cause remains unclear. TRPV1 agonists have also demonstrated reduced pain with no serious adverse events - the most common adverse events include a burning or warming sensation upon administration. c)Targeting the NGF and TRPV1 pathways appear effective for reducing OA pain, but further work is needed to better understand which patients may benefit most from these treatments. The anti-NGF antibody tanezumab and the TRPV1 agonist CNTX-4975 have both received fast-track designation from the FDA for the treatment of OA pain.

NGF mediates protection of mesenchymal stem cells-conditioned medium against 2,5-hexanedione-induced apoptosis of VSC4.1 cells via Akt/Bad pathway.

It has been shown that the conditioned medium of bone mesenchymal stem cells (BMSC-CM) can inhibit apoptosis of neural cells exposed to 2,5-hexanedione (HD), but its protective mechanism remains unclear. To investigate the underlying mechanism, VSC4.1 cells were given HD and 5, 10 and 15% BMSC-CM (v/v) in the current experiment. Our data showed that BMSC-CM concentration-dependently attenuated HD-induced cell apoptosis. Moreover, BMSC-CM remarkably decreased the mitochondrial cytochrome c (Cyt C) release and the caspase-3 activity in HD-given VSC4.1 cells. Given a relatively high expression of NGF in BMSCs and BMSC-CM, we hypothesized that NGF might be an important mediator of the protection of BMSC-CM against apoptosis induced by HD. To verify our hypothesis, the VSC4.1 cells were administrated with NGF and anti-NGF antibody in addition to HD. As expected, NGF could perfectly mimic BMSC-CM's protective role and these beneficial effects were abolished by anti-NGF antibody intervention. To further explore its mechanism, inhibitors of TrkA and Akt were given to the VSC4.1 cells and NGF/Akt/Bad pathway turned out to be involved in anti-apoptotic role of BMSC-CM. Based on these findings, it was revealed that BMSC-CM beneficial role was mediated by NGF and relied on the Akt/Bad pathway.

Nerve growth factor antibody for the treatment of osteoarthritis pain and chronic low-back pain: mechanism of action in the context of efficacy and safety.

Chronic pain continues to be a significant global burden despite the availability of a variety of nonpharmacologic and pharmacologic treatment options. Thus, there is a need for new analgesics with novel mechanisms of action. In this regard, antibodies directed against nerve growth factor (NGF-Abs) are a new class of agents in development for the treatment of chronic pain conditions such as osteoarthritis and chronic low-back pain. This comprehensive narrative review summarizes evidence supporting pronociceptive functions for NGF that include contributing to peripheral and central sensitization through tropomyosin receptor kinase A activation and stimulation of local neuronal sprouting. The potential role of NGF in osteoarthritis and chronic low-back pain signaling is also examined to provide a mechanistic basis for the observed efficacy of NGF-Abs in clinical trials of these particular pain states. Finally, the safety profile of NGF-Abs in terms of common adverse events, joint safety, and nerve structure/function is discussed.

Evaluation of the Toxicity and Neurological Effects of Fulranumab in Adult Cynomolgus Monkeys.

Fulranumab, an anti-human nerve growth factor antibody, was evaluated in a series of nonclinical toxicology studies. No treatment effects were observed in adolescent cynomolgus monkeys in standard design, repeat-dose toxicology studies of up to 6 months. Adverse effects on the developing nervous system were observed in offspring of pregnant cynomolgus monkeys treated with fulranumab. Subsequent studies including detailed morphologic investigations of the nervous system did reveal fulranumab-related changes in adult cynomolgus monkeys; this article is focused on those findings. A single dose of ≥1 mg/kg fulranumab administered subcutaneously (SC) caused a decrease in neuron and sympathetic ganglion size (superior cervical ganglion), observed morphologically and stereologically, with a resulting appearance of increased glial cell density. Similar results were observed in repeat-dose (15 to 52 weeks) toxicity studies at ≤50 mg/kg/wk fulranumab SC. These effects recovered after a 3-month treatment-free period. Fulranumab did not cause any neuronal death, necrosis, apoptosis, or any apparent decrease in function of sympathetic neurons/ganglia at any time point examined. A no observed effect level (NOEL) was established at 0.25 mg/kg fulranumab SC every 4 weeks for 28 weeks.

Systemic Depletion of Nerve Growth Factor Inhibits Disease Progression in a Genetically Engineered Model of Pancreatic Ductal Adenocarcinoma.

In patients with pancreatic ductal adenocarcinoma (PDAC), increased expression of proinflammatory neurotrophic growth factors (eg, nerve growth factor [NGF]) correlates with a poorer prognosis, perineural invasion, and, with regard to NGF, pain severity. We hypothesized that NGF sequestration would reduce inflammation and disease in the KPC mouse model of PDAC. Following biweekly injections of NGF antibody or control immunoglobulin G, beginning at 4 or 8 weeks of age, inflammation and disease stage were assessed using histological, protein expression, and quantitative polymerase chain reaction analyses. In the 8-week anti-NGF group, indicators of neurogenic inflammation in the dorsal root ganglia (substance P and calcitonin gene-related peptide) and spinal cord (glial fibrillary acidic protein) were significantly reduced. In the 4-week anti-NGF group, TRPA1 mRNA in dorsal root ganglia and spinal phosphorylated ERK protein were elevated, but glial fibrillary acidic protein expression was unaffected. In the 8-week anti-NGF group, there was a 40% reduction in the proportion of mice with microscopic perineural invasion, and no macrometastases were observed. Anti-NGF treatment beginning at 4 weeks may increase inflammation and negatively impact disease. Treatment starting at 8 weeks (after disease onset), however, reduces neural inflammation, neural invasion, and metastasis. These data indicate that NGF impacts PDAC progression and metastasis in a temporally dependent manner.

Discovery of Potent, Selective, and Peripherally Restricted Pan-Trk Kinase Inhibitors for the Treatment of Pain.

Hormones of the neurotrophin family, nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), neurotrophin 3 (NT3), and neurotrophin 4 (NT4), are known to activate the family of Tropomyosin receptor kinases (TrkA, TrkB, and TrkC). Moreover, inhibition of the TrkA kinase pathway in pain has been clinically validated by the NGF antibody tanezumab, leading to significant interest in the development of small molecule inhibitors of TrkA. Furthermore, Trk inhibitors having an acceptable safety profile will require minimal brain availability. Herein, we discuss the discovery of two potent, selective, peripherally restricted, efficacious, and well-tolerated series of pan-Trk inhibitors which successfully delivered three candidate quality compounds 10b, 13b, and 19. All three compounds are predicted to possess low metabolic clearance in human that does not proceed via aldehyde oxidase-catalyzed reactions, thus addressing the potential clearance prediction liability associated with our current pan-Trk development candidate PF-06273340.

Discovery of Allosteric, Potent, Subtype Selective, and Peripherally Restricted TrkA Kinase Inhibitors

Tropomyosin receptor kinases (TrkA, TrkB, TrkC) are activated by hormones of the neurotrophin family: nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), neurotrophin 3 (NT3), and neurotrophin 4 (NT4). Moreover, the NGF antibody tanezumab has provided clinical proof of concept for inhibition of the TrkA kinase pathway in pain leading to significant interest in the development of small molecule inhibitors of TrkA. However, achieving TrkA subtype selectivity over TrkB and TrkC via a Type I and Type II inhibitor binding mode has proven challenging and Type III or Type IV allosteric inhibitors may present a more promising selectivity design approach. Furthermore, TrkA inhibitors with minimal brain availability are required to deliver an appropriate safety profile. Herein, we describe the discovery of a highly potent, subtype selective, peripherally restricted, efficacious, and well-tolerated series of allosteric TrkA inhibitors that culminated in the delivery of candidate quality compound 23.

Efficacy of nerve growth factor antibody in a knee osteoarthritis pain model in mice

BackgroundNerve growth factor (NGF) is not only an important factor in nerve growth but also a major contributor to the production of inflammation. It has been reported that inhibiting NGF could reduce several types of pain in several animal models. Here, we aimed to clarify the efficacy of NGF antibody in a knee osteoarthritis (OA) pain model in mice.MethodSix-week-old male C57BR/J mice were used (n = 30). Ten mice comprised the control group, which received saline injection into the right knee joints; the other 20 mice comprised the experimental group, which received monoiodoacetate (MIA) injection into the right knee joints. Three weeks after surgery, the 20 experimental mice were randomly placed into treatment groups which received either sterile saline (non-treat group: 10 mg/kg, i.p.) or an anti-NGF antibody (anti-NGF group: 10 mg/kg, i.p.). Simultaneously, all mice received fluorogold (FG) retrograde neurotracer injection into their right joints. In a behavioral study, we evaluated gait using the CatWalk quantitative gait analysis system before surgery, 3 weeks after surgery (before treatment), 4 weeks after surgery (one week after surgery), and 5 weeks after surgery (2 weeks after surgery). In immunohistochemical analysis, the right dorsal root ganglia (DRGs) from the L4–L6 levels were resected 5 weeks after surgery (2 weeks after surgery). They were immunostained for calcitonin gene-related peptide (CGRP), and the number of FG-labeled or CGRP-immunoreactive (IR) DRG neurons was counted.ResultsOn gait analysis using the CatWalk system, duty cycle, swing speed, and print area were decreased in non-treat group compared with those in control group and improved in the anti-NGF group compared with those in non-treat group. CGRP expression in DRGs was up-regulated in non-treat group compared with that in control group and suppressed in the anti-NGF group compared with that in non-treat group (both p < 0.05).ConclusionsMIA injection into the knee joint induced gait impairment and the up-regulation of CGRP in DRG neurons in a knee OA pain model in mice. Intraperitoneal injection of anti-NGF antibody suppressed this impairment of gait and up-regulation of CGRP in DRG neurons. These finding suggest that anti-NGF therapy might be valuable in the treatment of OA pain in the knee.

Development of an imaging mitigation strategy for patient enrolment in the tanezumab nerve growth factor inhibitor (NGF-ab) program with a focus on eligibility assessment.

Nerve growth factor antibodies (NGF-ab) have shown promising analgesic efficacy. Aim was to describe reader training efforts and present reliability data focusing on radiographic eligibility in the tanezumab program. A multi-step process was used for reader calibration and reliability testing. First, a reference standard set of cases was created and diagnostic performance was evaluated. A second exercise focused on agreement of ordinal assessment (Kellgren-Lawrence grading) of radiographic osteoarthritis. Subsequently, 11 readers were trained and read a test set of 100 cases focused on eligibility assessments. Additional reliability testing and calibration of five core readers assessing eligibility of 30 cases was performed 3 and 6 months after study start. Sensitivity for the reference standard readings ranged from 0.50 to 0.90 and specificity from 0.40 to 0.83. Overall agreement for Kellgren-Lawrence grading ranged from 71.4% to 82.9%. For the 11 reader exercise, in 76% of cases at least 8 of 11 readers agreed on eligibility status. For the reliability testing 3 months after study start, in 80.0% of cases at least 4 of 5 readers agreed on eligibility with a κ = 0.43 (95% CI: 0.32-0.54). For the reliability testing after 6 months, in 83.3% of cases at least 4 of 5 readers agreed on eligibility with a κ = 0.52 (95% CI: 0.41-0.63). After intense efforts spent in the development of an imaging program for an NGF-ab clinical program, the achieved reliability for eligibility assessment is substantial but not perfect. Ongoing efforts of calibration prior to including additional readers to the program and during study conduct between current readers will be needed to ensure agreement on potential adverse events and radiographic disease severity.