A systematic review of the efficacy and general safety of antibodies to NGF in the treatment of OA of the hip or knee

Efficacy, Safety, and Tolerability of ONO-4474, an Orally Available Pan-Tropomyosin Receptor Kinase Inhibitor, in Japanese Patients With Moderate to Severe Osteoarthritis of the Knee: A Randomized, Placebo-Controlled, Double-Blind, Parallel-Group Comparative Study

We examined the efficacy, safety, and tolerability of ONO-4474 in Japanese patients with osteoarthritis (OA) of the knee. In this multicenter, placebo-controlled, randomized, double-blind, parallel-group comparative study, patients with moderate to severe OA who were refractory to nonsteroidal anti-inflammatory drugs were orally administered 100 mg of ONO-4474 twice daily for 28 days. The primary end point was knee pain during walking, assessed by visual analog scale over 24 hours (VAS₂₄ ). Treatment-emergent adverse events (TEAEs) and adverse drug reactions were reported for safety. In total, 110 patients were randomized (1:1) to receive placebo or ONO-4474. The mean (standard deviation) change in VAS₂₄ scores at week 4 was -26.9 (25.0) mm in the ONO-4474 group and -19.5 (19.6) mm in the placebo group. The difference (ONO-4474 group - placebo group) in posterior mean change in VAS₂₄ at week 4 was -5.8 (posterior standard deviation, 4.4; 95% confidence interval, -14.3 to 2.8) mm. TEAEs were reported in 41.8% of patients in the ONO-4474 group and 18.2% of patients in the placebo group. The most common TEAEs in the ONO-4474 group related to the musculoskeletal system and the peripheral and central nervous systems were myalgia (7.3%), arthralgia (5.5%), dizziness (3.6%), and hypoesthesia (3.6%). Four patients from the ONO-4474 group and 1 patient from the placebo group discontinued treatment because of AEs; however, none were judged to be serious, and all patients recovered or were recovering after discontinuation. ONO-4474 is a novel tropomyosin receptor kinase inhibitor that has an analgesic effect in patients with OA.

Novel Approaches to Persistent Pain Therapy

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

Serum-based soluble markers differentiate psoriatic arthritis from osteoarthritis

Objectives

We aimed to identify soluble biomarkers that differentiate psoriatic arthritis (PsA) from osteoarthritis (OA).

Methods

Markers of cartilage metabolism (cartilage oligomeric matrix protein [COMP], hyaluronan), metabolic syndrome (adiponectin, adipsin, resistin, hepatocyte growth factor [HGF], insulin, leptin) and inflammation (C-reactive protein [CRP], interleukin-1β [IL-1β], IL-6, IL-8, tumour necrosis factor alpha [TNFα], monocyte chemoattractant protein-1 [MCP-1], nerve growth factor [NGF]) were compared in serum samples from 201 patients with OA, 77 patients with PsA and 76 controls. Levels across the groups were compared using the Kruskal-Wallis test. Pairwise comparisons were made with Wilcoxon rank-sum test. Multivariate logistic regression analyses were performed to identify markers that differentiate PsA from OA. Receiver operating characteristic (ROC) curves were constructed based on multivariate models. The final model was further validated in an independent set of 73 PsA and 75 OA samples using predicted probabilities calculated with coefficients of age, sex and biomarkers.

Results

Levels of the following markers were significantly different across the three groups (p<0.001)—COMP, hyaluronan, resistin, HGF, insulin, leptin, CRP, IL-6, IL-8, TNFα, MCP-1, NGF. In multivariate analysis, COMP (OR 1.24, 95% CI 1.06 to 1.46), resistin (OR 1.26, 95% CI 1.07 to 1.48), MCP-1 (OR 1.10, 95% CI 0.07 to 1.48) and NGF (OR<0.001, 95% CI <0.001 to 0.25) were found to be independently associated with PsA versus OA. The area under the ROC curve (AUROC) for this model was 0.99 compared with model with only age and sex (AUROC 0.87, p<0.001). Similar results were obtained using the validation sample.

Conclusion

A panel of four biomarkers may distinguish PsA from OA. These results need further validation in prospective studies.

Overlapping features of rapidly progressive osteoarthrosis and Charcot arthropathy

Nerve growth factor (NGF) is the primary neurotrophin in the skeleton and a central mediator of skeletal pain. Recent trials of anti-NGF neutralizing antibodies have resulted in infrequent but well-described incidence of rapidly progressive osteoarthrosis (RPOA). Neuropathy, whether from syphilis or diabetes, is also associated with severe joint destruction, known as neuroarthropathy or Charcot joint. These commonalities of severe joint destruction with either loss of a neurotrophin (anti-NGF) or a deficit of functional skeletal innervation led us to examine our institutional case files for potential radio-pathologic overlap between RPOA and Charcot joint.

Emerging therapeutic agents in osteoarthritis

Osteoarthritis (OA) is the most common joint disorder and a leading cause of disability. Current treatments for OA can improve symptoms but do not delay the progression of disease. In the last years, much effort has been devoted to developing new treatments for OA focused on pain control, inflammatory mediators or degradation of articular tissues. Although promising results have been obtained in ex vivo studies and animal models of OA, few of these agents have completed clinical trials. Available clinical data support the interest of nerve growth factor as a target in pain control as well as the disease-modifying potential of inhibitors of Wnt signaling or catabolic enzymes such as aggrecanases and cathepsin K, and anabolic strategies like fibroblast growth factor-18 or cellular therapies. Carefully controlled studies in patients selected according to OA phenotypes and with a long follow-up will help to confirm the relevance of these new approaches as emerging therapeutic treatments in OA.

Autophagy Is Independent of the Chondroprotection Induced by Platelet-Rich Plasma Releasate

Background

Platelet-rich plasma (PRP) has been shown to be a promising therapeutic agent against osteoarthritis (OA), whereas its chondroprotection mechanism is not fully elucidated. Autophagy is considered an important biological process throughout the development of OA. Therefore, the objective of the present study is to investigate the role of autophagy in the chondroprotection and compare the effects of releasate between L-PRP and P-PRP.

Methods

PRP were prepared from rat blood. Rat chondrocytes pretreated in the presence or absence of interleukin-1 beta (IL-1β) were incubated with PRP releasate. The expressions of OA-related genes and autophagy-related genes were determined by RT-PCR and western blot, respectively. Autophagic bodies were assessed by transmission electron microscopy and the autophagy flux was monitored under the confocal microscopy. The effect of PRP on autophagy was further investigated in the milieu of autophagy activator, rapamycin, or autophagy inhibition by downregulation of Atg5. The effect of PRP on cartilage repair and autophagy was also evaluated in an OA rat model.

Results

In vitro, PRP releasate increased the expression of the anabolic genes, COL2 and Aggrecan, and decreased the expression of the catabolic genes, whereas the expression of autophage markers, Atg5 and Beclin-1, as well as the ratio of LC3 II/LC3 I, was not significantly altered in normal or IL-1β-treated chondrocytes. Similar expression pattern was found following the activation (rapamycin) or inhibition (Atg5 silencing) of autophagy. In vivo, PRP releasate ameliorated posttraumatic cartilage degeneration while the expression of LC3 was comparable to that in the vehicle treatment group.

Conclusions

PRP releasate promoted the anabolic gene expression, relieved inflammatory stress in chondrocytes, and ameliorated cartilage degeneration, but autophagy was independent of these processes.

H1-antihistamines are associated with lower prevalence of radiographic knee osteoarthritis: a cross-sectional analysis of the Osteoarthritis Initiative data

Background

There is growing evidence that mast cells (MCs) play a role in knee osteoarthritis (OA). H₁-antihistamines block H₁-receptors of histamine, which is an important mediator of MCs. There is a lack of data on whether H₁-antihistamines can influence OA. We hypothesized that the use of H₁-antihistamines may be linked to the reduced prevalence of knee OA.

Methods

Baseline data from the Osteoarthritis Initiative cohort were analysed cross-sectionally. Unadjusted and adjusted logistic regression models were performed to compare the prevalence of knee OA in H₁-antihistamine users and non-users. Generalized estimating equations were used to adjust for the correlation between knees. Knee OA was defined as (1) Kellgren-Lawrence (KL) grade ≥ 2 or total joint replacement or (2) KL grade ≥ 2 and joint space narrowing or total joint replacement.

Results

The analysed sample consisted of 8545 knees (664 knees of H₁-antihistamine users and 7881 knees of H₁-antihistamine non-users). The use of H₁-antihistamines was associated with reduced prevalence of knee OA in unadjusted and adjusted models using both the first (adjusted OR, 0.77; 95% CI, 0.62, 0.96; P < 0.02) and second (adjusted OR, 0.75; 95% CI, 0.62, 0.93; P < 0.008) definitions of knee OA.

Conclusions

H₁-antihistamines are associated with a reduced prevalence of knee OA. The findings indicate that this class of drugs should be further evaluated for possible structure-modifying properties in knee OA.

Nerve Growth Factor Antagonists: Is the Future of Monoclonal Antibodies Becoming Clearer?

Although there is an unmet need for pain medications that are both effective and safe, virtually no novel analgesics have been approved over the past two decades. In view of both experimental and clinical evidence of a major role for nerve growth factor (NGF) in the generation and maintenance of a wide range of pain states, the clinical development of humanised anti-nerve growth factor monoclonal antibodies (anti-NGF mAbs) aroused particular interest. However, the US Food and Drug Administration (FDA) placed a clinical hold on anti-NGF mAb clinical studies in late 2010, first because of reports of serious joint-related adverse events, and afterwards because of sympathetic nervous system safety concerns. The development programmes of tanezumab and fasinumab resumed after the FDA lifted its hold in March 2015, whereas other anti-NGF mAbs were dropped by their sponsors. This article provides an updated review on the analgesic efficacy and safety of anti-NGF agents based on data from fully published studies and public information from websites, and discusses the possible future role of these agents in managing chronic pain. The efficacy of anti-NGF mAbs was highly variable depending on the chronic pain condition studied. The most consistent and convincing results were obtained in patients with symptomatic osteoarthritis of the knee and/or hip. Conversely, studies in non-specific lower back pain and peripheral neuropathic pain generated mixed results. Finally, there was no conclusive evidence of the effectiveness of anti-NGF mAbs in cancer pain and urological chronic pelvic pain syndromes. Treatment-emergent adverse events were similar across anti-NGF mAbs, thus being suggestive of 'class-specific effects'. Although most patients tolerated anti-NGF agents well, neurosensory symptoms occurred frequently, and some patients developed new or worsened peripheral neuropathies. However, the most problematic safety issue was rapidly destructive arthropathies, leading to joint replacement surgery. To date, the aetiologies of joint-related side effects and their pathophysiology have not been clearly elucidated. However, some risk factors have been identified, such as higher doses of anti-NGF mAbs and longer drug exposure, concurrent nonsteroidal anti-inflammatory drug use and pre-existing subchondral insufficiency fractures. Taken together, the present data suggest that low-dose anti-NGF mABs may exhibit a favourable risk-benefit ratio in selected patients with certain chronic pain conditions, especially symptomatic osteoarthritis.

Emerging Treatment Models in Rheumatology: Challenges for Osteoarthritis Trials

At a time when advancing understanding of osteoarthritis (OA) has created opportunities for new treatments, development of treatments has remained considerably behind advances in other rheumatic diseases. We describe elements of trial design and measurements that have inhibited success and offer suggestions that may help break the log jam. Among the problems with trials that include pain as an outcome measure are reliance on a single, non-optimal pain outcome, overestimation of likely effects of treatments on pain, and failure to identify patient subgroups most likely to respond to specific treatments. With regard to the use of structure modification as an outcome measure, demonstrating structure modification is often highly challenging, even with the use of magnetic resonance imaging. Many OA patients have advanced disease that is unlikely to respond to treatments that prevent cartilage loss. Further, prevention of cartilage loss and reduction of pain correlate weakly at best, and in at least some patients, reduction in pain may actually increase joint damage, making it impossible to demonstrate dual treatment effects on structure and pain in such scenarios. For structure outcomes, treatment effects on pain-sensitive structures such as bone and synovium may be more achievable than preventing cartilage loss. We suggest that changes in trial design related to some of these issues may increase the chances that new exciting and effective OA treatments will become available.

What is the role of imaging in the clinical diagnosis of osteoarthritis and disease management?

While OA is predominantly diagnosed on the basis of clinical criteria, imaging may aid with differential diagnosis in clinically suspected cases. While plain radiographs are traditionally the first choice of imaging modality, MRI and US also have a valuable role in assessing multiple pathologic features of OA, although each has particular advantages and disadvantages. Although modern imaging modalities provide the capability to detect a wide range of osseous and soft tissue (cartilage, menisci, ligaments, synovitis, effusion) OA-related structural damage, this extra information has not yet favourably influenced the clinical decision-making and management process. Imaging is recommended if there are unexpected rapid changes in clinical outcomes to determine whether it relates to disease severity or an additional diagnosis. On developing specific treatments, imaging serves as a sensitive tool to measure treatment response. This narrative review aims to describe the role of imaging modalities to aid in OA diagnosis, disease progression and management. It also provides insight into the use of these modalities in finding targeted treatment strategies in clinical research.

What is new in pain modification in osteoarthritis?

There is a big need for the development of novel therapies for the safe management of chronic pain associated with OA. Here we reviewed PubMed (2015 onward) and ClinicalTrials.gov for ongoing and recently completed trials where pain in OA is the primary outcome measure. Three broad categories were identified: biological therapies, small molecules and cryoneurolysis. The most promising new strategy is blockade of nerve growth factor with antibodies. Two anti-nerve growth factor antibodies, tanuzemab and fasinumab, are in active development after the 2010 hold on trials was lifted in 2015. In addition, several active clinical trials are testing distinct mechanism-based interventions, including cytokine inhibition, selective μ, δ or κ opioid receptor agonists, zoledronate and intra-articular capsaicin. In addition to pharmacological approaches, cryoneurolytic strategies that directly target peripheral nerves may play a role in OA pain management, but efficacy profiles and long-term effects of such treatments need more study. Clearly, the therapeutic landscape for OA pain is rapidly expanding. Since symptomatic OA is a heterogeneous disease, the challenge will be to identify patients that will benefit the most from specific approaches.

Immunohistochemical localization of nerve growth factor, tropomyosin receptor kinase A, and p75 in the bone and articular cartilage of the mouse femur

Sequestration of nerve growth factor (NGF) significantly attenuates skeletal pain in both animals and humans. However, relatively little is known about the specific cell types that express NGF or its cognate receptors tropomyosin receptor kinase A (TrkA) and p75 in the intact bone and articular cartilage. In the present study, antibodies raised against NGF, TrkA, and p75 (also known as CD271) were used to explore the expression of these antigens in the non-decalcified young mouse femur. In general, all three antigens displayed a remarkably restricted expression in bone and cartilage with less than 2% of all DAPI+ cells in the femur displaying expression of any one of the three antigens. Robust NGF immunoreactivity was found in mostly CD-31− blood vessel-associated cells, a small subset of CD-31+ endothelial cells, an unidentified group of cells located at the subchondral bone/articular cartilage interface, and a few isolated, single cells in the bone marrow. In contrast, p75 and TrkA were almost exclusively expressed by nerve fibers located nearby NGF+ blood vessels. The only non-neuronal expression of either p75 or TrkA in the femur was the expression of p75 by a subset of cells located in the deep and middle zone of the articular cartilage. Understanding the factors that tightly regulate the basal level of expression in normal bone and how the expression of NGF, TrkA, and p75 change in injury, disease, and aging may provide insights into novel therapies that can reduce skeletal pain and improve skeletal health.

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

Background

Nerve 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.

Method

Six-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.

Results

On 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).

Conclusions

MIA 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.

Mechanisms of Osteoarthritic Pain. Studies in Humans and Experimental Models

Pain due to osteoarthritis (OA) is one of the most frequent causes of chronic pain. However, the mechanisms of OA pain are poorly understood. This review addresses the mechanisms which are thought to be involved in OA pain, derived from studies on pain mechanisms in humans and in experimental models of OA. Three areas will be considered, namely local processes in the joint associated with OA pain, neuronal mechanisms involved in OA pain, and general factors which influence OA pain. Except the cartilage all structures of the joints are innervated by nociceptors. Although the hallmark of OA is the degradation of the cartilage, OA joints show multiple structural alterations of cartilage, bone and synovial tissue. In particular synovitis and bone marrow lesions have been proposed to determine OA pain whereas the contribution of the other pathologies to pain generation has been studied less. Concerning the peripheral neuronal mechanisms of OA pain, peripheral nociceptive sensitization was shown, and neuropathic mechanisms may be involved at some stages. Structural changes of joint innervation such as local loss and/or sprouting of nerve fibers were shown. In addition, central sensitization, reduction of descending inhibition, descending excitation and cortical atrophies were observed in OA. The combination of different neuronal mechanisms may define the particular pain phenotype in an OA patient. Among mediators involved in OA pain, nerve growth factor (NGF) is in the focus because antibodies against NGF significantly reduce OA pain. Several studies show that neutralization of interleukin-1β and TNF may reduce OA pain. Many patients with OA exhibit comorbidities such as obesity, low grade systemic inflammation and diabetes mellitus. These comorbidities can significantly influence the course of OA, and pain research just began to study the significance of such factors in pain generation. In addition, psychologic and socioeconomic factors may aggravate OA pain, and in some cases genetic factors influencing OA pain were found. Considering the local factors in the joint, the neuronal processes and the comorbidities, a better definition of OA pain phenotypes may become possible. Studies are under way in order to improve OA and OA pain monitoring.

Pain in osteoarthritis. Implications for optimal management

Pain is an ubiquitous symptom in osteoarticular diseases, occurring much more commonly than stiffness or disability. OA of the knee, hand, or hip affects around 20% of adults in various populations and is dramatically increasing in many countries, mostly related to age and obesity, leading to an increased number of people having OA pain, and creating a huge burden related to disability and health care costs. OA-related pain, has been classically considered to be a nociceptive pain condition. Clinicians have considered pain to be an alarm signal, correlated to the intensity of joint degradation. In OA, most authors have focused their studies on joint architecture and local degradation, considering pain as only a symptom, a consequence of joint damage. However, OA-related pain is a specific disease, with a complex pathophysiology, including neuropathic peripheral and central abnormalities, together with local inflammation involving all joint structures. Clinical findings emphasize that it is not a stable and linear condition, that pain experience is independent of structural modifications, and that the quality of pain in OA is important to consider, aside from its intensity. OA-related pain is modulated by many factors, including the individual patient's psychological and genetic factors, as well as the theoretical role of meteorological influences. Recent neuroimaging findings have improved our knowledge about central mechanisms of OA pain, especially in persistent cases.

Developing drugs in cancer-related bone pain

INTRODUCTION

Cancer-related bone pain is a frequent and important key problem for metastatic patients that may reduce quality of life, with related limitations in daily activities and morbidity. Often traditional approach to pain may fail given the complex pathophysiology of this phenomenon.

METHODS

The aim of this review is to describe promising therapies for cancer-related bone pain, from the pathophysiology to the clinical trials currently ongoing. Moreover, any new evidence for better approach to cancer-related bone pain with the traditional drugs is also considered.

CONCLUSIONS

In clinical practice opioids remain the most important pharmacologic treatment for severe pain related to bone cancer. Regard developing drugs, anti-NGF and anti-TrkA are the most investigated new drug in this setting, but a future role in clinical practice is still uncertain.

Mechanism and therapeutic effectiveness of nerve growth factor in osteoarthritis pain

Osteoarthritis (OA) is the most common form of articular joint arthritis and a cause of significant morbidity. In this review, we present the role of nerve growth factor (NGF) in pain generation, relationship between NGF and OA pain, and pathogenic factors (interleukin-1β, transforming growth factor-β1, mechanical loading, and adipokines) involved in OA development. Since NGF blocking is an efficient way to inhibit OA-associated pain, we summarize four categories of drugs that target NGF/tropomyosin receptor kinase A (TrkA) signaling. In addition, we discuss the future of NGF/TrkA antagonists and underline their potential for use in OA pain relief. A better understanding of the causes and treatment of OA will facilitate the development of more effective methods of OA pain management.

New Therapeutic Targets for Osteoarthritis Pain

Osteoarthritis (OA), the most common form of arthritis, causes pain and disability, as well as emotional distress. While total joint replacement is one of the most effective treatments available for improving the quality of life in people with severe OA, it is not suitable for all patients and all joints. Current pharmacological analgesics have limited efficacy, and their use is often restricted by adverse events. Medications that might reduce pain by slowing or preventing structural disease remain elusive. Our increasing understanding of the complex mechanisms that underlie OA pain offers a wide range of potential new treatment targets. New drugs for OA pain might come from repurposing those developed for other conditions, as well as novel compounds targeting pain mechanisms specific to the joint. Here we discuss the mechanisms of OA pain and its therapeutic implications. We explore evolving treatment modalities, including combination treatment. We review recent research and patents pointing to future OA therapies. We discuss the potential for biomarkers to facilitate drug development and targeting.

Nerve growth factor blockade for the management of osteoarthritis pain: what can we learn from clinical trials and preclinical models?

PURPOSE OF REVIEW

Anti-nerve growth factor (NGF) antibodies hold tremendous potential for the management of osteoarthritis pain, but clinical trials have revealed serious adverse effects that are incompletely understood. This review discusses clinical trial results along with preclinical studies that have assessed NGF blockade in experimental osteoarthritis, in order to provide insight for future studies.

RECENT FINDINGS

Systematic reviews have revealed that anti-NGF therapy, including tanezumab, is efficacious in improving pain and function, but serious adverse events, including rapidly progressive osteoarthritis and osteonecrosis, resulted in a moratorium on trials that was only recently lifted. Within the past year, preclinical testing has revealed effects of NGF blockade on both pain behaviors and joint structure in experimental models of osteoarthritis. Similar to clinical trial results, these studies in laboratory animals demonstrated analgesic efficacy of NGF blockade. Interestingly, several animal studies have suggested detrimental effects on joint integrity as a result of treatment, particularly when treatment is started early in the disease, when joint damage is mild to moderate.

SUMMARY

NGF blockade continues to represent a promising new approach for the treatment of osteoarthritis pain, but the actual benefits and risks remain to be fully elucidated. Preclinical models may suggest patient populations that could be best served while limiting side-effects, but future work should further investigate the mechanisms of benefits and unwanted side-effects.

Breaking barriers to novel analgesic drug development

Acute and chronic pain complaints, although common, are generally poorly served by existing therapies. This unmet clinical need reflects a failure to develop novel classes of analgesics with superior efficacy, diminished adverse effects and a lower abuse liability than those currently available. Reasons for this include the heterogeneity of clinical pain conditions, the complexity and diversity of underlying pathophysiological mechanisms, and the unreliability of some preclinical pain models. However, recent advances in our understanding of the neurobiology of pain are beginning to offer opportunities for developing novel therapeutic strategies and revisiting existing targets, including modulating ion channels, enzymes and G-protein-coupled receptors.

Hopes for the Future of Pain Control

Here we aim to present an accessible review of the pharmacological targets for pain management, and succinctly discuss the newest trends in pain therapy. A key task for current pain pharmacotherapy is the identification of receptors and channels orchestrating nociception. Notwithstanding peripheral alterations in the receptors and channels following pathophysiological events, the modulatory mechanisms in the central nervous system are also fundamental to the regulation of pain perception. Bridging preclinical and clinical studies of peripheral and central components of pain modulation, we present the different types of pain and relate these to pharmacological interventions. We firstly highlight the roles of several peripheral nociceptors, such as NGF, CGRP, sodium channels, and TRP-family channels that may become novel targets for therapies. In the central nervous system, the roles of calcium channels and gabapentinoids as well as NMDA receptors in generating excitability are covered including ideas on central sensitization. We then turn to central modulatory systems and discuss opioids and monoamines. We aim to explain the importance of central sensitization and the dialogue of the spinal circuits with the brain descending modulatory controls before discussing a mechanism-based effectiveness of antidepressants in pain therapy and their potential to modulate the descending controls. Emphasizing the roles of conditioned pain modulation and its animal's equivalent, diffuse noxious inhibitory controls, we discuss these unique descending modulations as a potential tool for understanding mechanisms in patients suffering from pain. Mechanism-based therapy is the key to picking the correct treatments and recent clinical studies using sensory symptoms of patients as surrogates for underlying mechanisms can be used to subgroup patients and reveal actions of drugs that may be lost when studying heterogenous groups of patients. Key advances in the understanding of basic pain principles will impact our thinking about therapy targets. The complexity of pain syndromes will require tailored pharmacological drugs, often in combination or through drugs with more than one action, and often psychotherapy, to fully control pain.

Beyond TNF: TNF superfamily cytokines as targets for the treatment of rheumatic diseases

TNF blockers are highly efficacious at dampening inflammation and reducing symptoms in rheumatic diseases such as rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis, and also in nonrheumatic syndromes such as inflammatory bowel disease. As TNF belongs to a superfamily of 19 structurally related proteins that have both proinflammatory and anti-inflammatory activity, reagents that disrupt the interaction between proinflammatory TNF family cytokines and their receptors, or agonize the anti-inflammatory receptors, are being considered for the treatment of rheumatic diseases. Biologic agents that block B cell activating factor (BAFF) and receptor activator of nuclear factor-κB ligand (RANKL) have been approved for the treatment of systemic lupus erythematosus and osteoporosis, respectively. In this Review, we focus on additional members of the TNF superfamily that could be relevant for the pathogenesis of rheumatic disease, including those that can strongly promote activity of immune cells or increase activity of tissue cells, as well as those that promote death pathways and might limit inflammation. We examine preclinical mouse and human data linking these molecules to the control of damage in the joints, muscle, bone or other tissues, and discuss their potential as targets for future therapy of rheumatic diseases.

Fulranumab in patients with interstitial cystitis/bladder pain syndrome: observations from a randomized, double-blind, placebo-controlled study

BACKGROUND

This study was designed to evaluate the efficacy and safety of fulranumab, a fully human monoclonal antibody directed against nerve growth factor (NGF), for pain relief in patients with interstitial cystitis/bladder pain syndrome (IC/BPS).

METHODS

In this multicenter, double-blind study, adults with IC/BPS (i.e., interstitial cystitis symptom index [ICSI] total score ≥8) accompanied by chronic, moderate-to-severe pain were randomized to fulranumab 9 mg or matching placebo, administered subcutaneously at weeks 1, 5, and 9. The primary efficacy endpoint was change from baseline to study endpoint (week 12 or at withdrawal) in average daily pain intensity score. Key secondary endpoints included change from baseline to study endpoint in worst pain intensity score, ICSI total score, Pelvic Pain and Urgency/Frequency total score, Patient Perception of Bladder Condition score, and global response assessment.

RESULTS

This study was terminated prematurely based on concern that this class may be associated with rapidly progressing osteoarthritis or osteonecrosis. Thirty-one patients (of the targeted 70 patients) were randomized, 17 to placebo and 14 to fulranumab, with 15 and 10 patients, respectively, receiving all 3 doses of double-blind treatment. In ANOVA analyses, there was no statistically significant difference between treatment groups for the primary endpoint (LS mean difference [95% CI] vs. placebo, -0.2 [-1.52, 1.10]) or any of the secondary endpoints. Fulranumab was well tolerated, with no patient discontinuing due to an adverse event or experiencing a joint-related serious adverse event over a 26-week follow-up period. No events related to the neurologic or motor systems were reported.

CONCLUSIONS

Efficacy was not demonstrated in the present study with the single dose tested and a limited sample size, leading to lack of statistical power. These findings do not exclude the possibility that fulranumab would provide clinical benefit in a larger study and/or specific populations (phenotypes) in this difficult to treat pain condition.

TRIAL REGISTRATION

NCT01060254 , registered January 29, 2010.

Osteoarthritis: from pathogenic mechanisms and recent clinical developments to novel prospective therapeutic options

Osteoarthritis (OA) is a degenerative joint disease that, despite recent progress, has no curative treatment. Considerable research has recently been initiated to identify new potential therapeutic targets. In this review, we will set forth some of the major discoveries in the past 5 years, notably those dealing with the identification of pathogenic factors [hypoxia-inducible factors (HIFs), complement, transforming growth factor (TGF)-β and zinc-ZIP8]. New drugs and concepts currently in clinical development [anti-nerve growth factor (NGF), mesenchymal stromal cells and fibroblast growth factor (FGF)-18] will then be addressed. Finally, we will consider prospective avenues that could lead to mid-to-long-term developments of novel therapeutic concepts, notably those dealing with autophagy regulation and induced pluripotent stem cells.

Emerging Targets for the Management of Osteoarthritis Pain

Worldwide, osteoarthritis (OA) is one of the leading causes of chronic pain, for which adequate relief is not available. Ongoing peripheral input from the affected joint is a major factor in OA-associated pain. Therefore, this review focuses predominantly on peripheral targets emerging in the preclinical and clinical arena. Nerve growth factor is the most advanced of these targets, and its blockade has shown tremendous promise in clinical trials in knee OA. A number of different types of ion channels, including voltage-gated sodium channels and calcium channels, transient receptor potential channels, and acid-sensing ion channels, are important for neuronal excitability and play a role in pain genesis. Few channel blockers have been tested in preclinical models of OA, with varying results. Finally, we discuss some examples of G-protein coupled receptors, which may offer attractive therapeutic strategies for OA pain, including receptors for bradykinin, calcitonin gene-related peptide, and chemokines. Since many of the pathways described above can be selectively and potently targeted, they offer an exciting opportunity for pain management in OA, either systemically or locally.

Preventing painful age-related bone fractures: Anti-sclerostin therapy builds cortical bone and increases the proliferation of osteogenic cells in the periosteum of the geriatric mouse femur

Age-related bone fractures are usually painful and have highly negative effects on a geriatric patient’s functional status, quality of life, and survival. Currently, there are few analgesic therapies that fully control bone fracture pain in the elderly without significant unwanted side effects. However, another way of controlling age-related fracture pain would be to preemptively administer an osteo-anabolic agent to geriatric patients with high risk of fracture, so as to build new cortical bone and prevent the fracture from occurring. A major question, however, is whether an osteo-anabolic agent can stimulate the proliferation of osteogenic cells and build significant amounts of new cortical bone in light of the decreased number and responsiveness of osteogenic cells in aging bone. To explore this question, geriatric and young mice, 20 and 4 months old, respectively, received either vehicle or a monoclonal antibody that sequesters sclerostin (anti-sclerostin) for 28 days. From days 21 to 28, animals also received sustained administration of the thymidine analog, bromodeoxyuridine (BrdU), which labels the DNA of dividing cells. Animals were then euthanized at day 28 and the femurs were examined for cortical bone formation, bone mineral density, and newly borne BrdU+ cells in the periosteum which is a tissue that is pivotally involved in the formation of new cortical bone. In both the geriatric and young mice, anti-sclerostin induced a significant increase in the thickness of the cortical bone, bone mineral density, and the proliferation of newly borne BrdU+ cells in the periosteum. These results suggest that even in geriatric animals, anti-sclerostin therapy can build new cortical bone and increase the proliferation of osteogenic cells and thus reduce the likelihood of painful age-related bone fractures.

Bone marrow lesions in hip osteoarthritis are characterized by increased bone turnover and enhanced angiogenesis

OBJECTIVE

Bone marrow lesions (BML), previously denoted bone marrow edema, are detected as water signals by magnetic resonance imaging (MRI). Previous histologic studies were unable to demonstrate any edematous changes at the tissue level. Therefore, our aim was to investigate the underlying biological mechanisms of the water signal in MRI scans of bone affected by BML.

METHODS

Tetracycline labeling in addition to water sensitive MRI scans of 30 patients planned for total hip replacement surgery was undertaken. Twenty-one femoral heads revealed BML on MRI, while nine were negative and used as controls (CON). Guided by the MRI images cylindrical biopsies were extracted from areas with BML in the femoral heads. Tissue sections from the biopsies were subjected to histomorphometric image analyses of the cancellous bone envelope.

RESULTS

Patients with BML exhibited an average 40- and 18-fold increase of bone formation rate and mineralizing surface, respectively. Additionally, samples with BML demonstrated 2-fold reduction of marrow fat and 28-fold increase of woven bone. Immunohistochemical analysis showed a 4-fold increase of angiogenesis markers CD31 and von Willebrand Factor (vWF) in the BML-group compared to CON.

CONCLUSION

This study indicates that BML are characterized by increased bone turnover, vascularity and angiogenesis in keeping with it being a reparatory process. Thus, the water signal, which is the hallmark of BML on MRI, is most probably reflecting increased tissue vascularity accompanying increased remodeling activity.

Monoclonal antibodies for the treatment of osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a multifactorial chronic joint disease, and so far, there are no approved disease-modifying anti-OA drugs (DMOADs). There is an urgent need to develop therapies for different phenotypes of OA. Monoclonal antibodies (mAb) may slow structural progression, control inflammation and relieve pain, and thus have the potential to be DMOADs. Areas covered: In this review, the authors searched the literature on PubMed, EMBASE and the Cochrane Library using keywords, including mAbs, biological agents, OA and osteoarthritis, electronically up to May 2016. They also included abstracts of international conferences. Furthermore, they reviewed experimental and clinical studies of various mAbs targeting different pathological mechanisms of OA, including ADAMTS, Interleukine-1, tumour necrosis factor, never growth factor and vascular endothelial growth factor. Expert opinion: MAbs for the treatment of OA are under intense investigation and the results for some mAbs (e.g., anti-nerve growth factor mAbs, anti- vascular endothelial growth factor mAbs) are promising. The authors believe that mAb therapy can be a targeted therapeutic approach for the treatment of OA. Future clinical trials are required to evaluate the therapeutic efficacy of these agents by the appropriate selection of specific phenotype for targeted therapy based on the mechanism of drug action.

Challenges to develop novel anti-inflammatory and analgesic drugs

Chronic inflammatory diseases and persistent pain of different origin represent common medical, social, and economic burden, and their pharmacotherapy is still an unresolved issue. Therefore, there is a great and urgent need to develop anti-inflammatory and analgesic agents with novel mechanisms of action, but it is a very challenging task. The main problem is the relatively large translational gap between the preclinical experimental data and the clinical results due to characteristics of the models, difficulties with the investigational techniques particularly for pain, as well as species differences in the mechanisms. We summarize here the current state-of-the-art medication and related ongoing strategies, and the novel targets with lead molecules under clinical development. The first members of the gold-standard categories, such as nonsteroidal anti-inflammatory drugs, glucocorticoids, and opioids, were introduced decades ago, and since then very few drugs with novel mechanisms of action have been successfully taken to the clinics despite considerable development efforts. Several biologics targeting different key molecules have provided breakthrough in some autoimmune/inflammatory diseases, but they are expensive, only parenterally available, their long-term side effects often limit their administration, and they do not effectively reduce pain. Some kinase inhibitors and phosphodiesterase-4 blockers have recently been introduced as new directions. There are in fact some promising novel approaches at different clinical stages of drug development focusing on transient receptor potential vanilloid 1/ankyrin 1 channel antagonism, inhibition of voltage-gated sodium/calcium channels, several enzymes (kinases, semicarbazide-sensitive amine oxidases, and matrix metalloproteinases), cytokines/chemokines, transcription factors, nerve growth factor, and modulation of several G protein-coupled receptors (cannabinoids, purinoceptors, and neuropeptides). WIREs Nanomed Nanobiotechnol 2017, 9:e1427. doi: 10.1002/wnan.1427 For further resources related to this article, please visit the WIREs website.

The role of progranulin in arthritis

Progranulin (PGRN) is a growth factor with a unique beads-on-a-string structure that is involved in multiple pathophysiological processes, including anti-inflammation, tissue repair, wound healing, neurodegenerative diseases, and tumorigenesis. This review presents up-to-date information concerning recent studies on the role of PGRN in inflammatory arthritis and osteoarthritis, with a special focus on the involvement of the interactions and interplay between PGRN and tumor necrosis factor receptor (TNFR) family members in regulating such musculoskeletal diseases. In addition, this paper highlights the applications of atsttrin, an engineered protein comprising three TNFR-binding fragments of PGRN, as a promising intervention in treating arthritis.

A Feline-Specific Anti-Nerve Growth Factor Antibody Improves Mobility in Cats with Degenerative Joint Disease-Associated Pain: A Pilot Proof of Concept Study

Background

Neutralizing antibodies against nerve growth factor (NGF) are analgesic in rodent models, naturally occurring degenerative joint disease (DJD) pain in dogs, and chronic pain in humans.

Objectives

To evaluate the efficacy of a fully felinized anti‐NGF antibody (NV‐02) for the treatment of DJD pain and mobility impairment in cats.

Animals

Thirty‐four client‐owned cats with DJD‐associated pain and mobility impairment.

Methods

In a placebo‐controlled, pilot, masked clinical study, cats were randomized to a single treatment with NV‐02 (0.4 mg/kg SC [n = 11] or 0.8 mg/kg SC [n = 12]) or placebo (saline, SC [n = 11]). Activity was measured objectively. Additionally, owners completed clinical metrology instruments (client‐specific outcome measures [CSOM] and feline musculoskeletal pain index [FMPI]) on days 0 (screening), 14 (baseline), 35, 56, and 77. A repeated‐measures model was used to evaluate the objective activity data.

Results

NV‐02 significantly increased objectively measured activity overall (P = .017) and at 2 (P = .035), 3 (P = .007), 4 (P = .006), 5 (P = .007), and 6 (P = .017) weeks after treatment. CSOM scores (P = .035) and pain (P = .024) showed a significant effect of treatment 3 weeks after administration. In the treatment group, 83% of the owners correctly identified the treatment administered compared with 45% of owners in the placebo group (P = .013). No treatment‐related adverse effects were identified.

Conclusions

These pilot data demonstrate a 6‐week duration positive analgesic effect of this fully felinized anti‐NGF antibody in cats suffering from DJD‐associated pain.

Tanezumab for Patients with Osteoarthritis of the Knee: A Meta-Analysis

OBJECTIVE

Tanezumab is a new therapeutic intervention for patients with osteoarthritis (OA) of the knee. We performed the present meta-analysis to appraise the efficacy and safety of tanezumab for patients with knee OA.

METHODS

We systematically searched randomized controlled trials from PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL). The primary outcomes were mean change in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, the WOMAC physical function and patient's global assessment (PGA). Outcomes were reported as the standard mean difference (SMD) or relative risk (RR) with 95% confidence interval (CI). We assessed the pooled data using a random-effects model.

RESULTS

Of the identified studies, four were eligible and were included in this meta-analysis (N = 1839 participants). Compared with the placebo groups, tanezumab yielded a significant reduction in mean change in the WOMAC pain (SMD = 0.51, 95% CI 0.34 to 0.69, P<0.00001), the WOMAC physical function (SMD = 0.56, 95% CI 0.38 to 0.74, P<0.00001) and PGA (SMD = 0.34, 95% CI 0.22 to 0.47, P<0.00001). There was no significant difference in serious adverse events (RR = 1.06, 95% CI 0.59 to 1.92, P = 0.84) between the tanezumab and placebo groups. Tanezumab significantly increased discontinuations due to adverse events (RR = 2.89, 95% CI 1.59 to 5.26, P = 0.0005), abnormal peripheral sensations (RR = 3.14, 95% CI 2.12 to 4.66, P<0.00001), and peripheral neuropathy (RR = 6.05, 95% CI 2.32 to 15.81, P = 0.0002).

CONCLUSION

Tanezumab can alleviate pain and improve function for patients with OA of the knee. However, considering the limited number of studies, this conclusion should be interpreted cautiously and more clinical randomized controlled trials are needed to verify the efficacy and safety of tanezumab for OA of the knee.

Anti-nerve growth factor in pain management: current evidence

There continues to be an unmet need for safe and effective pain medications. Opioids and nonsteroidal anti-inflammatory drugs (NSAIDs) dominate the clinical landscape despite limited effectiveness and considerable side-effect profiles. Although significant advancements have identified myriad potential pain targets over the past several decades, the majority of new pain pharmacotherapies have failed to come to market. The discovery of nerve growth factor (NGF) and its interaction with tropomyosin receptor kinase A (trkA) have been well characterized as important mediators of pain initiation and maintenance, and pharmacotherapies targeting this pathway have the potential to be considered promising methods in the treatment of a variety of nociceptive and neuropathic pain conditions. Several methodologic approaches, including sequestration of free NGF, prevention of NGF binding and trkA activation, and inhibition of trkA function, have been investigated in the development of new pharmacotherapies. Among these, NGF-sequestering antibodies have exhibited the most promise in clinical trials. However, in 2010, reports of rapid joint destruction leading to joint replacement prompted the US Food and Drug Administration (FDA) to place a hold on all clinical trials involving anti-NGF antibodies. Although the FDA has since lifted this hold and a number of new trials are under way, the long-term efficacy and safety profile of anti-NGF antibodies are yet to be established.

Peripheral Brain Derived Neurotrophic Factor Precursor Regulates Pain as an Inflammatory Mediator

The precursor of brain derived neurotrophic factor (proBDNF), the unprocessed BDNF gene product, binds to its receptors and exerts the opposing biologic functions of mature BDNF. proBDNF is expressed in the peripheral tissues but the functions of peripheral proBDNF remain elusive. Here we showed that proBDNF and its predominant receptor, p75 pan-neurotrophin receptor were upregulated in the nerve fibers and inflammatory cells in the local tissue in inflammatory pain. Neutralization of proBDNF by polyclonal antibody attenuated pain in different models of inflammatory pain. Unilateral intra-plantar supplementation of proBDNF by injecting exogenous proBDNF or ectopic overexpression resulted in pain hypersensitivity and induced spinal phosphorylated extracellular signal-regulated kinase activation. Exogenous proBDNF injection induced the infiltration of inflammatory cells and the activation of proinflammatory cytokines, suggesting that inflammatory reaction contributed to the pro-algesic effect of proBDNF. Finally, we generated monoclonal anti-proBDNF antibody that could biologically block proBDNF. Administration of monoclonal Ab-proBDNF attenuated various types of inflammatory pain and surgical pain. Thus, peripheral proBDNF is a potential pain mediator and anti-proBDNF pretreatment may alleviate the development of inflammatory pain.

Non-surgical treatments for the management of early osteoarthritis

Non-surgical treatments are usually the first choice for the management of knee degeneration, especially in the early osteoarthritis (OA) phase when no clear lesions or combined abnormalities need to be addressed surgically. Early OA may be addressed by a wide range of non-surgical approaches, from non-pharmacological modalities to dietary supplements and pharmacological therapies, as well as physical therapies and novel biological minimally invasive procedures involving injections of various substances to obtain a clinical improvement and possibly a disease-modifying effect. Numerous pharmaceutical agents are able to provide clinical benefit, but no one has shown all the characteristic of an ideal treatment, and side effects have been reported at both systemic and local level. Patients and physicians should have realistic outcome goals in pharmacological treatment, which should be considered together with other conservative measures. Among these, exercise is an effective conservative approach, while physical therapies lack literature support. Even though a combination of these therapeutic options might be the most suitable strategy, there is a paucity of studies focusing on combining treatments, which is the most common clinical scenario. Further studies are needed to increase the limited evidence on non-surgical treatments and their combination, to optimize indications, application modalities, and results with particular focus on early OA. In fact, most of the available evidence regards established OA. Increased knowledge about degeneration mechanisms will help to better target the available treatments and develop new biological options, where preliminary results are promising, especially concerning early disease phases. Specific treatments aimed at improving joint homoeostasis, or even counteracting tissue damage by inducing regenerative processes, might be successful in early OA, where tissue loss and anatomical changes are still at very initial stages.

Alleviation of pain in painful diabetic neuropathy

INTRODUCTION

Painful diabetic neuropathy (PDN) is a disabling pain condition. Its pathomechanism remains unknown, but a sensitization and neuronal hyperexcitabilty have been suggested. Only symptomatic pharmacological pain management treatment is currently available.

AREAS COVERED

The origin of PDN is enigmatic, and the evidence-based therapeutic guidelines therefore consist only of antidepressants and antiepileptics as first-line recommended drugs. This article relates to a MEDLINE/PubMed systematic search (2005-2015).

EXPERT OPINION

The results of the meta-analysis from the aspect of the efficacy of amitriptyline, duloxetine, venlafaxine, gabapentin and pregabalin are favorable, but the placebo response rate is relatively high in patients with neuropathic pain. For personalization of the medication of PDN patients, the optimum dosing, the genotyping of the metabolizing enzymes and optimum biomarkers are needed. As concerns the future perspectives, specific sodium channel subtype inhibitors acting on peripheral nociceptive neurons or modified T-type voltage-gated calcium channel blockers may be promising targets for pharmaceutical innovations. Another attractive strategy for the treatment is based on the effects of monoclonal antibodies against nerve growth factor, sodium channels, specific receptor and cytokines. Botulinum toxin A, capsaicin patch and spinal cord stimulation therapies are the nearest future therapeutic options for the treatment of PDN patients.

Altered joint tribology in osteoarthritis: Reduced lubricin synthesis due to the inflammatory process. New horizons for therapeutic approaches

Osteoarthritis (OA) is the most common form of joint disease. This review aimed to consolidate the current evidence that implicates the inflammatory process in the attenuation of synovial lubrication and joint tissue homeostasis in OA. Moreover, with these findings, we propose some evidence for novel therapeutic strategies for preventing and/or treating this complex disorder. The studies reviewed support that inflammatory mediators participate in the onset and progression of OA after joint injury. The flow of pro-inflammatory cytokines following an acute injury seems to be directly associated with altered lubricating ability in the joint tissue. The latter is associated with reduced level of lubricin, one of the major joint lubricants. Future research should focus on the development of new therapies that attenuate the inflammatory process and restore lubricin synthesis and function. This approach could support joint tribology and synovial lubrication leading to improved joint function and pain relief.