Subcutaneous tanezumab for osteoarthritis of the hip or knee: efficacy and safety results from a 24-week randomised phase III study with a 24-week follow-up period

A comprehensive review of phase 2/3 trials in osteoarthritis: an expert opinion

INTRODUCTION

Osteoarthritis (OA) is a chronic, degenerative, and debilitating disease associated with significant long-term morbidity and disability. The pathogenesis of OA is not completely understood but involves an interplay between environmental risk factors, joint mechanics, abnormal pain pathways and upregulation of inflammatory signaling pathways. Current therapeutic options for patients are limited to conservative management, minimal pharmacological options or surgical management, with significant caveats to all approaches.

AREAS COVERED

In this review, we have set out to investigate current phase II/III clinical trials by undertaking a PubMed search. Examined clinical trials have explored a myriad of potential therapeutics from conventional disease-modifying anti-rheumatic drugs and biologics usually used in the treatment of inflammatory arthritides, to more novel approaches targeting inflammatory pathways implicated in OA, cartilage degeneration or pain pathways.

EXPERT OPINION

Unfortunately, most completed phase II/III clinical trials have shown little impact on patient pain scores, with the exception of the traditional DMARD methotrexate and Sprifermin. Methotrexate has been shown to be beneficial when used in the correct patient cohort (MRI proven synovitis). Sprifermin has the longest follow-up data of 5 years and has been shown to reduce loss of MRI-measured cartilage thickness and pain scores.

Pain Reduction With Oral Methotrexate in Knee Osteoarthritis : A Randomized, Placebo-Controlled Clinical Trial

BACKGROUND

Treatments for osteoarthritis (OA) are limited. Previous small studies suggest that the antirheumatic drug methotrexate may be a potential treatment for OA pain.

OBJECTIVE

To assess symptomatic benefits of methotrexate in knee OA (KOA).

DESIGN

A multicenter, randomized, double-blind, placebo-controlled trial done between 13 June 2014 and 13 October 2017. (ISRCTN77854383; EudraCT: 2013-001689-41).

SETTING

15 secondary care musculoskeletal clinics in the United Kingdom.

PARTICIPANTS

A total of 207 participants with symptomatic, radiographic KOA and knee pain (severity ≥4 out of 10) on most days in the past 3 months with inadequate response to current medication were approached for inclusion.

INTERVENTION

Participants were randomly assigned 1:1 to oral methotrexate once weekly (6-week escalation 10 to 25 mg) or matched placebo over 12 months and continued usual analgesia.

MEASUREMENTS

The primary end point was average knee pain (numerical rating scale [NRS] 0 to 10) at 6 months, with 12-month follow-up to assess longer-term response. Secondary end points included knee stiffness and function outcomes and adverse events (AEs).

RESULTS

A total of 155 participants (64% women; mean age, 60.9 years; 50% Kellgren-Lawrence grade 3 to 4) were randomly assigned to methotrexate (n = 77) or placebo (n = 78). Follow-up was 86% (n = 134; methotrexate: 66, placebo: 68) at 6 months. Mean knee pain decreased from 6.4 (SD, 1.80) at baseline to 5.1 (SD, 2.32) at 6 months in the methotrexate group and from 6.8 (SD, 1.62) to 6.2 (SD, 2.30) in the placebo group. The primary intention-to-treat analysis showed a statistically significant pain reduction of 0.79 NRS points in favor of methotrexate (95% CI, 0.08 to 1.51; P = 0.030). There were also statistically significant treatment group differences in favor of methotrexate at 6 months for Western Ontario and McMaster Universities Osteoarthritis Index stiffness (0.60 points [CI, 0.01 to 1.18]; P = 0.045) and function (5.01 points [CI, 1.29 to 8.74]; P = 0.008). Treatment adherence analysis supported a dose-response effect. Four unrelated serious AEs were reported (methotrexate: 2, placebo: 2).

LIMITATION

Not permitting oral methotrexate to be changed to subcutaneous delivery for intolerance.

CONCLUSION

Oral methotrexate added to usual medications demonstrated statistically significant reduction in KOA pain, stiffness, and function at 6 months.

PRIMARY FUNDING SOURCE

Versus Arthritis.

NGF-BMSC-SF/CS composites for repairing knee joint osteochondral defects in rabbits: evaluation of the repair effect and potential underlying mechanisms

BACKGROUND

With the rapid growth of the ageing population, chronic diseases such as osteoarthritis have become one of the major diseases affecting the quality of life of elderly people. The main pathological manifestation of osteoarthritis is articular cartilage damage. Alleviating and repairing damaged cartilage has always been a challenge. The application of cartilage tissue engineering methods has shown promise for articular cartilage repair. Many studies have used cartilage tissue engineering methods to repair damaged cartilage and obtained good results, but these methods still cannot be used clinically. Therefore, this study aimed to investigate the effect of incorporating nerve growth factor (NGF) into a silk fibroin (SF)/chitosan (CS) scaffold containing bone marrow-derived mesenchymal stem cells (BMSCs) on the repair of articular cartilage defects in the knees of rabbits and to explore the possible underlying mechanism involved.

MATERIALS AND METHODS

Nerve growth factor-loaded sustained-release microspheres were prepared by a double emulsion solvent evaporation method. SF/CS scaffolds were prepared by vacuum drying and chemical crosslinking. BMSCs were isolated and cultured by density gradient centrifugation and adherent culture. NGF-SF/CS-BMSC composites were prepared and implanted into articular cartilage defects in the knees of rabbits. The repair of articular cartilage was assessed by gross observation, imaging and histological staining at different time points after surgery. The repair effect was evaluated by the International Cartilage Repair Society (ICRS) score and a modified Wakitani score. In vitro experiments were also performed to observe the effect of different concentrations of NGF on the proliferation and directional differentiation of BMSCs on the SF/CS scaffold.

RESULTS

In the repair of cartilage defects in rabbit knees, NGF-SF/CS-BMSCs resulted in higher ICRS scores and lower modified Wakitani scores. The in vitro results showed that there was no significant correlation between the proliferation of BMSCs and the addition of different concentrations of NGF. Additionally, there was no significant difference in the protein and mRNA expression of COL2a1 and ACAN between the groups after the addition of different concentrations of NGF.

CONCLUSION

NGF-SF/CS-BMSCs improved the repair of articular cartilage defects in the knees of rabbits. This repair effect may be related to the early promotion of subchondral bone repair.

New therapeutic strategies in osteoarthritis

Osteoarthritis (OA) is the most prevalent arthritis-type and is a major contributor to chronic joint pain, impaired physical function, and limited mobility. By the end of 2020, a total of 595 million, equal to 7·6% of the global population, had OA; this figure is expected to rise exponentially by 2050. Even while the disorder's intricate pathophysiology is starting to appear intelligible, we are yet to have a cure for the disorder. OA is typically managed with traditional palliative measures, such as topical and systemic analgesics, including non-steroidal anti-inflammatory drugs, therapeutic exercise, and braces. Sometimes, intra-articular glucocorticoids, viscosupplementation, or regenerative interventions provide short-term pain relief and functional improvement; some may require arthroplasty. Researchers continue their efforts to unveil a new therapeutic target to be effective in OA that modifies symptoms and arrests disease progression as well. In the present literature review, insights into new therapeutic strategies in OA, for example, liposome-based dexamethasone, microspore-based triamcinolone, nerve growth factor antagonist, anti-ADAMTS-5 (A Disintegrin And Metalloproteinase Thrombospoidin Motifs - 5), pentosan polysulfate sodium, allogeneic stem cells, C-C chemokine receptor type-4 (CCR4) ligand 17 inhibitor, Wnt-signaling inhibitor, and anti-obesity medications are provided.

Effect size varies based on calculation method and may affect interpretation of treatment effect: an illustration using randomised clinical trials in osteoarthritis

BACKGROUND

To illustrate how (standardised) effect sizes (ES) vary based on calculation method and to provide considerations for improved reporting.

METHODS

Data from three trials of tanezumab in subjects with osteoarthritis were analyzed. ES of tanezumab versus comparator for WOMAC Pain (outcome) was defined as least squares difference between means (mixed model for repeated measures analysis) divided by a pooled standard deviation (SD) of outcome scores. Three approaches to computing the SD were evaluated: Baseline (the pooled SD of WOMAC Pain values at baseline [pooled across treatments]); Endpoint (the pooled SD of these values at the time primary endpoints were assessed); and Median (the median pooled SD of these values based on the pooled SDs across available timepoints). Bootstrap analyses were used to compute 95% confidence intervals (CI).

RESULTS

ES (95% CI) of tanezumab 2.5 mg based on Baseline, Endpoint, and Median SDs in one study were - 0.416 (- 0.796, - 0.060), - 0.195 (- 0.371, - 0.028), and - 0.196 (- 0.373, - 0.028), respectively; negative values indicate pain improvement. This pattern of ES differences (largest with Baseline SD, smallest with Endpoint SD, Median SD similar to Endpoint SD) was consistent across all studies and doses of tanezumab.

CONCLUSION

Differences in ES affect interpretation of treatment effect. Therefore, we advocate clearly reporting individual elements of ES in addition to its overall calculation. This is particularly important when ES estimates are used to determine sample sizes for clinical trials, as larger ES will lead to smaller sample sizes and potentially underpowered studies.

TRIAL REGISTRATION

Clinicaltrials.gov NCT02697773, NCT02709486, and NCT02528188.

Sema3A secreted by sensory nerve induces bone formation under mechanical loads

Bone formation and deposition are initiated by sensory nerve infiltration in adaptive bone remodeling. Here, we focused on the role of Semaphorin 3A (Sema3A), expressed by sensory nerves, in mechanical loads-induced bone formation and nerve withdrawal using orthodontic tooth movement (OTM) model. Firstly, bone formation was activated after the 3rd day of OTM, coinciding with a decrease in sensory nerves and an increase in pain threshold. Sema3A, rather than nerve growth factor (NGF), highly expressed in both trigeminal ganglion and the axons of periodontal ligament following the 3rd day of OTM. Moreover, in vitro mechanical loads upregulated Sema3A in neurons instead of in human periodontal ligament cells (hPDLCs) within 24 hours. Furthermore, exogenous Sema3A restored the suppressed alveolar bone formation and the osteogenic differentiation of hPDLCs induced by mechanical overload. Mechanistically, Sema3A prevented overstretching of F-actin induced by mechanical overload through ROCK2 pathway, maintaining mitochondrial dynamics as mitochondrial fusion. Therefore, Sema3A exhibits dual therapeutic effects in mechanical loads-induced bone formation, both as a pain-sensitive analgesic and a positive regulator for bone formation.

Pathogenic Mechanisms and Therapeutic Approaches in Obesity-Related Knee Osteoarthritis

The knee is the joint most frequently involved in osteoarthritis, a common joint disorder in the adult population that is associated with significant chronic joint pain, reduced mobility and quality of life. Recent studies have established an association between obesity and the development of knee osteoarthritis that goes beyond the increased mechanical load on the knees as weight-bearing joints. This link is based on the maintenance of a chronic low-grade inflammation, altered secretion of adipokines by the adipose tissue and development of sarcopenia. Major adipokines involved in the pathogenesis of obesity-related knee osteoarthritis include adiponectin, which appears to have a protective effect, as well as leptin, resistin and visfatin, which are associated with higher pain scores and more severe structural damage. Joint pain in knee osteoarthritis may be both nociceptive and neuropathic and is the result of complex mechanisms driven by nerve growth factor, calcitonin gene-related peptide and pro-inflammatory cytokines. The role of endogenous cannabinoids and gut microbiota in common mechanisms between obesity and knee pain has recently been studied. The aim of the present review is to highlight major pathogenic mechanisms in obesity-related knee osteoarthritis with special attention on pain and to comment on possible therapeutic approaches.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Characterization of adverse joint outcomes in patients with osteoarthritis treated with subcutaneous tanezumab

OBJECTIVE

Due to the risk of rapidly progressive osteoarthritis (RPOA), the phase III studies of subcutaneous (SC) tanezumab in patients with moderate to severe hip or knee osteoarthritis (OA) included comprehensive joint safety surveillance. This pooled analysis summarizes these findings.

METHOD

Joint safety events in the phase III studies of SC tanezumab (2 placebo- and 1- nonsteroidal anti-inflammatory drug [NSAID]-controlled) were adjudicated by a blinded external committee. Outcomes of RPOA1 and RPOA2, primary osteonecrosis, subchondral insufficiency fracture, and pathological fracture comprised the composite joint safety endpoint (CJSE). Potential patient- and joint-level risk factors for CJSE, RPOA, and total joint replacement (TJR) were explored.

RESULTS

Overall, 145/4541 patients (3.2%) had an adjudicated CJSE (0% placebo; 3.2% tanezumab 2.5 mg; 6.2% tanezumab 5 mg; 1.5% NSAID). There was a dose-dependent risk of adjudicated CJSE, RPOA1, and TJR with tanezumab vs NSAID. Patient-level cross-tabulation found associations between adjudicated RPOA with more severe radiographic/symptomatic (joint pain, swelling, and physical limitation) OA. Risk of adjudicated RPOA1 was highest in patients with Kellgren-Lawrence (KL) grade 2 or 3 OA at baseline. Risk of adjudicated RPOA2 or TJR was highest in patients with KL grade 4 joints at baseline. A higher proportion of joints with adjudicated RPOA2 had a TJR (14/26) than those with adjudicated RPOA1 (16/106).

CONCLUSION

In placebo- and NSAID controlled studies of SC tanezumab for OA, adjudicated CJSE, RPOA, and TJR most commonly occurred in patients treated with tanezumab and with more severe radiographic or symptomatic OA. NCT02697773; NCT02709486; NCT02528188.

Asymmetric Flexion Contracture is Associated With Leg Length Inequality in Patients With Knee Osteoarthritis: Data From the Osteoarthritis Initiative

OBJECTIVE

To evaluate whether knee flexion contracture (FC) was associated with leg length inequality (LLI) and/or morbidity in knee osteoarthritis (OA).

DESIGN

We accessed 2 databases: (1) the Osteoarthritis Initiative (OAI) cohort, including participants with, or at-risk of OA, and (2) the Ottawa Knee Osteoarthritis cross-sectional database (OKOA), including participants with primary advanced knee OA. Both included demographics, radiographic data, knee range of motion, leg length, pain, and function scales.

SETTING

Tertiary care academic rheumatology and orthopedic clinics.

PARTICIPANTS

Patients with or at-risk of primary OA. We included 881 OAI and 72 OKOA participants (N=953).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

The primary outcome tested the association between the difference in knee extensions of the OA and contralateral knees (the knee extension difference, or KExD) and LLI. This was evaluated using bivariate regression, followed by a multivariable linear regression model.

RESULTS

OAI participants had less severe knee OA [Kellgren and Lawrence (KL) score 1.9±1.3] vs OKOA (KL score 3.4±0.6). The KExD correlated with LLI for both databases (OAI: R=0.167; P≤.001; OKOA: R=0.339; P=.004). Multivariable regression showed an effect of KExD on LLI in both databases (OAI: β=0.37[0.18,0.57]; P<.001, OKOA: β=0.73[0.20,1.26]; P=.007). When broken down by subgroup, the OAI moderate-severe OA group showed a significant effect of KExD on LLI (β=0.60 [0.34,0.85]; P<.001).

CONCLUSIONS

OA-related loss of knee extension was associated with LLI for those with moderate-severe OA. Because LLI correlates with worse knee OA symptoms, discovering an FC should cue clinicians to evaluate for LLI, an easily-treatable finding that may help reduce OA-associated morbidity for those approaching the need for arthroplasty.

Placebo effects in osteoarthritis: implications for treatment and drug development

Osteoarthritis (OA) is the most common form of arthritis worldwide, affecting ~500 million people, yet there are no effective treatments to halt its progression. Without any structure-modifying agents, management of OA focuses on ameliorating pain and improving function. Treatment approaches typically have modest efficacy, and many patients have contraindications to recommended pharmacological treatments. Drug development for OA is hindered by the gradual and progressive nature of the disease and the targeting of established disease in clinical trials. Additionally, new medications for OA cannot receive regulatory approval without demonstrating improvements in both structure (pathological features of OA) and symptoms (reduced pain and/or improved function). In clinical trials, people with OA show high 'placebo responses', which hamper the ability to identify new effective treatments. Placebo responses refer to the individual variability in response to placebos given in the context of clinical trials and other settings. Placebo effects refer specifically to short-lasting improvements in symptoms that occur because of physiological changes. To mitigate the effects of the placebo phenomenon, we must first understand what it is, how it manifests, how to identify placebo responders in OA trials and how these insights can be used to improve clinical trials in OA. Leveraging placebo responses and effects in clinical practice might provide additional avenues to augment symptom management of OA.

Prediction of relative change in free nerve growth factor following subcutaneous administration of tanezumab, a novel monoclonal antibody to nerve growth factor

Tanezumab is a monoclonal antibody against nerve growth factor (NGF). We investigated tanezumab pharmacokinetic (PK)-NGF relationships and predicted the extent of systemic free NGF suppression with target-mediated drug disposition (TMDD) modeling using data from three pivotal phase III interventional studies (NCT02697773, NCT02709486, and NCT02528188) in patients with osteoarthritis. Patients received tanezumab 2.5 mg or 5 mg every 8 weeks (q8w) subcutaneously. A TMDD model using a previously established population PK model was used to describe plasma tanezumab and serum total NGF concentration data, and simulations were performed to predict "unobserved" free NGF versus time profiles and dose-response relationships for free NGF. A total of 2992 patients had available data for plasma tanezumab or serum total NGF concentrations and were included in the analysis; 706 of these had data for both tanezumab and total NGF concentrations. The model generally performed well to predict observed total NGF concentrations up to ~24 weeks after each dose. Simulations suggested free NGF concentration would be suppressed by ~75% (median) near the peak of tanezumab concentration and by less than 5% (median) around the trough tanezumab concentration with a tanezumab 2.5 mg q8w regimen. Free NGF concentration was predicted to return to baseline level at ~8 weeks (95% prediction interval: 5-16 weeks) after the last tanezumab dose. This model adequately described plasma tanezumab and serum total NGF concentrations following s.c. administration of tanezumab 2.5 or 5 mg q8w, allowed prediction of relative change in systemic free NGF following s.c. administration of tanezumab.

Adaptation of the WOMAC for Use in a Patient Preference Study

OBJECTIVES

To adapt a patient-reported outcome (PRO) measure, the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC), into efficacy attributes for a discrete choice experiment (DCE) survey designed to quantify the relative importance of endpoints commonly used in knee osteoarthritis (KOA) trials.

METHODS

The adaptation comprised four steps: (1) selecting domains of interest; (2) determining presentation and framing of selected attributes; (3) determining attribute levels; and (4) developing choice tasks. This process involved input from multiple stakeholders, including regulators, health preference researchers, and patients. Pretesting was conducted to evaluate if patients comprehended the adapted survey attributes and could make trade-offs among them.

RESULTS

The WOMAC pain and function domains were selected for adaption to two efficacy attributes. Two versions of the discrete choice experiment (DCE) instrument were created to compare efficacy using (1) total domain scores and (2) item scores for "walking on a flat surface." Both attributes were presented as improvement from baseline scores by levels of 0%, 30%, 50%, and 100%. Twenty-six participants were interviewed in a pretest of the instrument (average age 60 years; 58% female; 62% had KOA for ≥ 5 years). The participants found both versions of attributes meaningful and relevant for treatment decision-making. They demonstrated willingness and ability to tradeoff improvements in pain and function separately, though many perceived them as inter-related.

CONCLUSIONS

This study adds to the growing literature regarding adapting PRO measures for patient preference studies. Such adaptation is important for designing a preference study that can incorporate a clinical trial's outcomes with PRO endpoints.

Peripheral Nerve Safety of Nerve Growth Factor Inhibition by Tanezumab: Pooled Analyses of Phase III Clinical Studies in Over 5000 Patients with Osteoarthritis

BACKGROUND

Tanezumab, a humanized anti-nerve growth factor antibody, was developed for the treatment of pain associated with osteoarthritis. Due to its mechanism of action, peripheral nerve safety was assessed in all clinical studies.

OBJECTIVES

To summarize the neurological safety of intravenous (IV) and subcutaneous (SC) tanezumab versus placebo in patients with osteoarthritis.

METHODS

Data were pooled from 3389 patients across seven studies that investigated IV administration, and from 1840 patients across three studies that investigated SC administration. The treatment period of each study ranged from 16 to 24 weeks, and follow-up periods ranged from 8 to 24 weeks. Neurological safety evaluations focused on adverse events (AEs) of abnormal peripheral sensation (APS), neurologic examinations, and consultations.

RESULTS

Across datasets, the incidence of AEs of APS was higher in tanezumab groups versus placebo. Paresthesia and hypoesthesia were the most frequently reported AEs in tanezumab-treated patients, compared with placebo. In both datasets, most AEs were of mild severity, resolved, and rarely resulted in discontinuation. In all treatment groups in both IV and SC studies, over 90% of patients had no new or worsened neurological examination abnormalities at the last study visit. Across datasets, mononeuropathy was diagnosed more frequently in tanezumab groups compared with placebo. Polyneuropathy was diagnosed in ≤ 0.9% of patients in tanezumab and placebo groups.

CONCLUSIONS

Tanezumab IV or SC had an increased incidence of AEs of APS, such as paresthesia and hypoesthesia, and diagnoses of mononeuropathy compared with placebo. However, tanezumab was not associated with generalized peripheral neuropathy.

CLINICALTRIALS

GOV IDENTIFIERS

NCT00733902, NCT00744471, NCT00830063, NCT00863304, NCT00863772, NCT01089725, NCT00985621, NCT02697773, and NCT02709486.

Pharmatherapeutic Treatment of Osteoarthrosis-Does the Pill against Already Exist? A Narrative Review

The aim of this narrative review is to summarize the current pharmacotherapeutic treatment options for osteoarthritis (OA). Is therapy still mainly symptomatic or does the pill against arthrosis already exist? Causal and non-causal, as well as future therapeutic approaches, are discussed. Various surgical and non-surgical treatment options are available that can help manage symptoms, slow down progression, and improve quality of life. To date, however, therapy is still mainly symptomatic, often using painkilling and anti-inflammatory drugs until the final stage, which is usually joint replacement. These "symptomatic pills against" have side effects and do not alter the progression of OA, which is caused by an imbalance between degenerative and regenerative processes. Next to resolving mechanical issues, the goal must be to gain a better understanding of the cellular and molecular basis of OA. Recently, there has been a lot of interest in cartilage-regenerative medicine and in the current style of treating rheumatoid arthritis, where drug therapy ("the pill against") has been established to slow down or even stop the progression of rheumatoid arthritis and has banned the vast majority of former almost regular severe joint destructions. However, the "causal pill against" OA does not exist so far. First, the early detection of osteoarthritis by means of biomarkers and imaging should therefore gain more focus. Second, future therapeutic approaches have to identify innovative therapeutic approaches influencing inflammatory and metabolic processes. Several pharmacologic, genetic, and even epigenetic attempts are promising, but none have clinically improved causal therapy so far, unfortunately.

What is new in pharmacological treatment for osteoarthritis?

Osteoarthritis (OA) is a degenerative joint disease in which structural changes of hyaline articular cartilage, subchondral bone, ligaments, capsule, synovium, muscles, and periarticular changes are involved. The knee is the most commonly affected joint, followed by the hand, hip, spine, and feet. Different pathological mechanisms are at play in each of these various involvement sites. Although systemic inflammation is more prominent in hand OA, knee and hip OA have been associated with excessive joint load and injury. As OA has varied phenotypes and the primarily affected tissues differ, treatment options must be tailored accordingly. In recent years, ongoing efforts have been made to develop disease-modifying options that halt or slow disease progression. Many are still in clinical trials, and as insights into the pathogenesis of OA evolve, novel therapeutic strategies will be developed. In this chapter, we provide an overview of the novel and emerging strategies in the management of OA.

Predicting Treatment Responses in Patients With Osteoarthritis: Results From Two Phase III Tanezumab Randomized Clinical Trials

Prediction of treatment responses is essential to move forward translational science. Our question was to identify patient-based variables that predicted responses to treatments. We conducted secondary analyses on pooled data from two randomized phase III clinical trials (NCT02697773 and NCT02709486) conducted in participants with moderate to severe osteoarthritis randomized to subcutaneous placebo (n = 514) or tanezumab 2.5 mg (n = 514). We used gradient boosted regression trees to identify variables that predicted Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain subscale scores at Week 16 and marginal plots to determine the directional relationship between each variable category and responses to placebo or tanezumab within the models. We also used Virtual Twins models to identify potential subgroups of response to the active treatment vs. placebo. We found that responses to placebo were predicted by baseline WOMAC Physical Function, baseline WOMAC Pain, the radiographic classification of the index joint, and the standard deviation of diary pain scores at baseline. In contrast, baseline WOMAC Pain along with failure of prior medications, duration of disease, and standard deviation of diary pain scores at baseline were predictive of tanezumab responses as expressed by the WOMAC Pain scores at Week 16. Those who responded to tanezumab vs. placebo were identified based on the radiographic classification of the index joint and either age or smoking status. These secondary-data analyses identified distinct and common patient-based variables to predict response to placebo or tanezumab. These findings will inform the design of future clinical trials, helping to move forward clinical pharmacology and translational science.

Examining the Relationships Among Treatment, Pain, and Physical Function in Patients With Osteoarthritis: A Mediation-Modeling Approach

OBJECTIVES

To better understand the relationships among treatment, pain, and physical function (PF).

METHODS

Data were collected from 2 published randomized clinical trials of osteoarthritis patients who received tanezumab or a placebo. PF was measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) PF domain. Pain (WOMAC pain domain) was a mediator of the effect of treatment on PF. A set of mediation models were investigated. Variables were treatment (tanezumab vs placebo), WOMAC pain domain, and WOMAC PF domain. Cross-sectional mediation models were assessed separately at different weeks. Longitudinal mediation models used data from all weeks simultaneously. Results could identify a steady-state period.

RESULTS

The cross-sectional and longitudinal mediation models showed a stable indirect effect of treatment through the pain on PF across time, indicating that a pseudo-steady-state model was appropriate. Therefore, the longitudinal steady-state mediation models were used with all available data assuming relationships among variables in the model being the same at all time points; results showed that the indirect effect of the treatment on PF was 77.8% in study 1 (NCT02697773) and 74.1% in study 2 (NCT02709486), both P <0.0001, whereas the direct effect was 22.2% for study 1 ( P = 0.0003) and 25.9% for study 2 ( P = 0.0019).

DISCUSSION

At least 75% of the treatment effect of tanezumab on physical functioning can be explained by the improvements in pain. However, tanezumab had an additional effect on physical functioning (~25%) that, was independent of improvements in pain. Such independent effects are of considerable interest and require further research to determine their mechanisms.

Nerve growth factor receptors in equine synovial membranes vary with osteoarthritic disease severity

Nerve growth factor (NGF) is a neurotrophin that has been implicated in pain signaling, apoptosis, inflammation and proliferation. The resultant effects depend on interaction with two different receptors; tyrosine kinase A (TrkA) and p75^NTR . NGF increases in synovial fluid from osteoarthritic joints, and monoclonal antibody therapy is trialed to treat osteoarthritis (OA)-related pain. Investigation of the complex and somewhat contradictory signaling pathways of NGF is conducted in neural research, but has not followed through to orthopaedic studies. The objectives of this study were to compare the expression of NGF receptors and the downstream regulator BAX in synovial membranes from joints in various stages of OA. The horse was used as a model. Synovial membranes were harvested from five healthy horses postmortem and from clinical cases with spontaneous OA undergoing arthroscopic surgery for lameness. Four horses with synovitis without gross cartilage changes, four horses with synovitis and cartilage damage, and four horses with synovitis and intracarpal fractures were included. Samples were investigated by immunohistochemistry and results showed that nuclear staining of TrkA, p75^NTR and BAX increases in OA-associated synovitis. TrkA expression increased in early disease stages whereas increases in p75^NTR were most prominent in later disease stages with cartilage damage and fibrosis. Clinical significance: Suppression of NGF may result in varied effects depending on different stages of the osteoarthritic disease process.

Osteoarthritis today: Lost in translation?

Osteoarthritis (OA) is a highly prevalent joint disease that is associated with pain, loss of function, and high direct and indirect economic costs. The current therapeutic options are inadequate, providing only a moderate symptom relief without the possibility of disease modification. While treatment options and personalized medicines are increasing for many complex diseases, OA drug development has been impeded by the advanced state of disease at the time of diagnosis and intervention, heterogeneity in both symptoms and rates of progression, and a lack of validated biomarkers and relevant outcome measures. This review article summarizes the OA landscape, including therapies in development as potential OA treatments, potential biomarkers undergoing evaluation by the US Food and Drug Administration, and a summary of current OA treatment guidelines, with a particular focus on the knee OA.

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

OBJECTIVE

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

METHODS

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

RESULTS AND DISCUSSION

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

CONCLUSIONS

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

The Current Role of Disease-modifying Osteoarthritis Drugs

Contemporary treatments for osteoarthritis (OA) pursue only to alleviate the pain caused by the illness. Discovering disease-modifying osteoarthritis drugs (DMOADs) that can induce the repair and regeneration of articular tissues would be of substantial usefulness. The purpose of this manuscript is to review the contemporary role of DMOADs in managing OA. A narrative literature review on the subject, exploring the Cochrane Library and PubMed (MEDLINE) was performed. It was encountered that many publications have analyzed the impact of several DMOAD methods, including anti-cytokine therapy (tanezumab, AMG 108, adalimumab, etanercept, anakinra), enzyme inhibitors (M6495, doxycycline, cindunistat, PG-116800), growth factors (bone morphogenetic protein-7, sprifermin), gene therapy (micro ribonucleic acids, antisense oligonucleotides), peptides (calcitonin) and others (SM04690, senolitic, transient receptor potential vanilloid 4, neural EGFL-like 1, TPCA-1, tofacitinib, lorecivivint and quercitrin). Tanezumab has been demonstrated to alleviate hip and knee pain in individuals with OA but can cause major adverse events (osteonecrosis of the knee, rapid illness progression, augmented prevalence of total joint arthroplasty of involved joints, particularly when tanezumab is combined with nonsteroidal anti-inflammatory drugs. SM04690 (a Wnt inhibitor) has been demonstrated to be safe and efficacious in alleviating pain and ameliorating function as measured by the Western Ontario and McMaster Universities Arthritis Index. The intraarticular injection of lorecivivint is deemed safe and well tolerated, with no important reported systemic complications. In conclusion, even though DMOADs seem promising, their clinical effectiveness has not yet been demonstrated for managing OA. Until forthcoming studies can proved the medications' capacity to repair and regenerate tissues affected by OA, physicians should keep using treatments that only intend to alleviate pain.

Osteoarthritis models: From animals to tissue engineering

Osteoarthritis (OA) is a chronic degenerative osteoarthropathy. Although it has been revealed that a variety of factors can cause or aggravate the symptoms of OA, the pathogenic mechanisms of OA remain unknown. Reliable OA models that accurately reflect human OA disease are crucial for studies on the pathogenic mechanism of OA and therapeutic drug evaluation. This review first demonstrated the importance of OA models by briefly introducing the OA pathological features and the current limitations in the pathogenesis and treatment of OA. Then, it mainly discusses the development of different OA models, including animal and engineered models, highlighting their advantages and disadvantages from the perspective of pathogenesis and pathology analysis. In particular, the state-of-the-art engineered models and their potential were emphasized, as they may represent the future direction in the development of OA models. Finally, the challenges in obtaining reliable OA models are also discussed, and possible future directions are outlined to shed some light on this area.

A Two-Step, Trajectory-Focused, Analytics Approach to Attempt Prediction of Analgesic Response in Patients with Moderate-to-Severe Osteoarthritis

INTRODUCTION

We sought to predict analgesic response to daily oral nonsteroidal anti-inflammatory drugs (NSAIDs) or subcutaneous tanezumab 2.5 mg (every 8 weeks) at week 16 in patients with moderate-to-severe osteoarthritis, based on initial treatment response over 8 weeks.

METHODS

Data were derived from three randomized controlled trials of osteoarthritis. A two-step, trajectory-focused, analytics approach was used to predict patients as responders or non-responders at week 16. Step 1 identified patients using a data-element combination method (based on pain score at baseline, pain score at week 8, pain score monotonicity at week 8, pain score path length at week 8, and body site [knee or hip]). Patients who could not be identified in step 1 were predicted in step 2 using a k-nearest neighbor method based on pain score and pain response level at week 8.

RESULTS

Our approach predicted response with high accuracy in NSAID-treated (83.2-90.2%, n = 931) and tanezumab-treated (84.6-91.0%, n = 1430) patients regardless of the efficacy measure used to assess pain, or the threshold used to define response (20%, 30%, or 50% improvement from baseline). Accuracy remained high using 50% or 20% response thresholds, with 50% and 20% yielding generally slightly better negative and positive predictive value, respectively, relative to 30%. Accuracy was slightly better in patients aged ≥ 65 years relative to younger patients across most efficacy measure/response threshold combinations.

CONCLUSIONS

Analyzing initial 8-week analgesic responses using a two-step, trajectory-based approach can predict future response in patients with moderate-to-severe osteoarthritis treated with NSAIDs or 2.5 mg tanezumab. These findings demonstrate that prediction of treatment response based on a single dose of a novel therapeutic is possible and that predicting future outcomes based on initial response offers a way to potentially advance the approach to clinical management of patients with osteoarthritis.

CLINICALTRIALS

GOV IDENTIFIERS

NCT02528188, NCT02709486, NCT02697773.

Efficacy and safety of tanezumab, NSAIDs, and placebo in patients with moderate to severe hip or knee osteoarthritis and a history of depression, anxiety, or insomnia: post-hoc analysis of phase 3 trials

Objective: Treatment outcomes for chronic pain can be poor in patients with depression, anxiety, or insomnia. This analysis evaluated the efficacy and safety of subcutaneous tanezumab, nonsteroidal anti-inflammatory drugs (NSAIDs), and placebo in patients with osteoarthritis (OA) and a history of these conditions using data from three phase 3 studies.Methods: A post-hoc analysis of data from two pooled placebo-controlled studies and one NSAID-controlled study of subcutaneous tanezumab. All patients had moderate to severe knee or hip OA that was inadequately controlled with standard-of-care analgesics. Efficacy outcomes were least-squares mean change from baseline to Week 16 in Western Ontario McMaster Universities OA Index (WOMAC) Pain, WOMAC Physical Function, Patient's global assessment of OA, and EQ-5D-5L scores. Results were summarized for patients with and without a history of depression, anxiety, or insomnia at baseline.Results: 1545 patients were treated in the pooled placebo-controlled studies (history of depression, 12%; anxiety, 8%; insomnia, 10%; any, 23%) and 2996 in the NSAID-controlled study (16%, 11%, 13%, 28%, respectively). In groups with positive histories, 38-80% took antidepressant or anxiolytic medications at baseline. Within treatments, largely similar improvements in efficacy outcomes were observed in patients with and without a history of depression, anxiety, or insomnia; the types of treatment-emergent adverse events were similar.Conclusions: Patients with OA and a history of depression, anxiety, or insomnia did not appear to experience reduced efficacy outcomes or an altered safety profile in response to tanezumab or NSAID treatment as compared with those without. NCT02697773; NCT02709486; NCT02528188.

Characterizing 16-Week Responder Profiles Using Group-Based Trajectory Modeling in Over 4300 Clinical Trial Participants Receiving Pharmaceutical Treatment for Moderate to Severe Osteoarthritis

INTRODUCTION

We sought to identify and characterize distinct responder profiles among osteoarthritis (OA) subjects treated with tanezumab, nonsteroidal anti-inflammatory drugs (NSAIDs), or placebo.

METHODS

Subject-level data were derived from three randomized, double-blind, placebo- or NSAID-controlled trials of tanezumab in subjects with moderate-to-severe OA. Subjects received subcutaneous tanezumab (2.5 mg, n = 1527; 5 mg, n = 1279) every 8 weeks, oral NSAIDs (n = 994) daily, or placebo (n = 513). Group-based trajectory modeling (GBTM, an application of finite mixture statistical modeling that uses response trajectory to identify and summarize complex patterns in longitudinal data) was used to identify subgroups of subjects following similar patterns of response in each treatment arm, based on daily pain intensity scores from baseline through Week 16. We then examined whether subject-related variables were associated with any of the subgroups using multinomial logistic regression.

RESULTS

A three-subgroup/four-inflection point trajectory model was selected based on clinical and statistical considerations. The subgroups were high responders (substantial pain improvement and a large majority of members achieved ≥ 30% improvement before Week 16), medium responders (gradual pain improvement and a majority of members achieved ≥ 30% improvement by Week 16), and non-responders (little to no pain improvement over 16 weeks). Across all treatments, fluctuation in pain intensity in the week prior to treatment was consistently associated with treatment response. Other variables were positively (age, body mass index, days of rescue medication use) or negatively (severity of disease based on Kellgren-Lawrence grading) associated with response but effects were small and/or varied across treatments.

CONCLUSIONS

Across all treatments, GBTM identified three subgroups of subjects that were characterized by extent of treatment response (high, medium, and non-responders). Similar analyses (e.g., grouping of subjects based on response trajectory and identification of subgroup-related variables) in other studies of OA could inform clinical trial design and/or treatment approaches. (NCT02697773; NCT02709486; NCT02528188).

Current understanding of osteoarthritis pathogenesis and relevant new approaches

Osteoarthritis (OA) is the most common degenerative joint disease that causes painful swelling and permanent damage to the joints in the body. The molecular mechanisms of OA are currently unknown. OA is a heterogeneous disease that affects the entire joint, and multiple tissues are altered during OA development. To better understand the pathological mechanisms of OA, new approaches, methods, and techniques need to be used to understand OA pathogenesis. In this review, we first focus on the epigenetic regulation of OA, with a particular focus on DNA methylation, histone modification, and microRNA regulation, followed by a summary of several key mediators in OA-associated pain. We then introduce several innovative techniques that have been and will continue to be used in the fields of OA and OA-associated pain, such as CRISPR, scRNA sequencing, and lineage tracing. Next, we discuss the timely updates concerning cell death regulation in OA pathology, including pyroptosis, ferroptosis, and autophagy, as well as their individual roles in OA and potential molecular targets in treating OA. Finally, our review highlights new directions on the role of the synovial lymphatic system in OA. An improved understanding of OA pathogenesis will aid in the development of more specific and effective therapeutic interventions for OA.

Biological Therapy for Osteoarthritis, Efficacy and Safety: Focus on Monoclonal Antibodies against Nerve Growth Factor and Fibroblast Growth Factor-18

Osteoarthritis (OA) is the most common chronic progressive musculoskeletal disease, affected cartilage, and surrounded tissues: Subchondral bones, ligaments, and meniscus. Current OA treatment based on non-steroidal anti-inflammatory drugs, acetaminophen (paracetamol), opioids, and intra-articular corticosteroid injections do not prevent the progression of the disease. Understanding of the pathogenesis of OA with continued structural damage accompanied by chronic pain led to appearance of monoclonal antibodies to fibroblast growth factor-18 (FGF)-18 and anti-nerve growth factor (NGF). This review provides an overview of biological therapy with FGF-18 and anti-NGF for OA. Search process was conducted in PubMed and Google Scholar for the following terms: “FGF-18” or “anti-NGF” and “OA,” “monoclonal antibody” and “OA.” Results of the analysis of clinical trials revealed that therapy targeting NGF resulted in significant analgesic effect and functional improvement of joints in OA; however, it was associated with considerable increase in adverse events. The mon\oclonal antibody to FGF-18 demonstrated the structure-modifying effects on cartilage with decrease the cartilage loss and improvement of cartilage thickness. However, further clinical longitudinal studies characterized the risk-benefit are needed to establish safety and efficacy of these medications.

Virus-like particle vaccinology, from bench to bedside

Virus-like particles (VLPs) have become key tools in biology, medicine and even engineering. After their initial use to resolve viral structures at the atomic level, VLPs were rapidly harnessed to develop antiviral vaccines followed by their use as display platforms to generate any kind of vaccine. Most recently, VLPs have been employed as nanomachines to deliver pharmaceutically active products to specific sites and into specific cells in the body. Here, we focus on the use of VLPs for the development of vaccines with broad fields of indications ranging from classical vaccines against viruses to therapeutic vaccines against chronic inflammation, pain, allergy and cancer. In this review, we take a walk through time, starting with the latest developments in experimental preclinical VLP-based vaccines and ending with marketed vaccines, which earn billions of dollars every year, paving the way for the next wave of prophylactic and therapeutic vaccines already visible on the horizon.

Efficacy, General Safety, and Joint Safety of Tanezumab in Japanese Patients with Osteoarthritis: Subgroup Analyses from Two Randomized, Phase 3 Studies

INTRODUCTION

Tanezumab is a monoclonal antibody against nerve growth factor that is under investigation for the treatment of osteoarthritis (OA) pain. We conducted subgroup analyses of two randomized phase 3 studies to summarize efficacy, general safety, and adjudicated joint safety of tanezumab in Japanese patients with moderate-to-severe OA.

METHODS

In Study 1 (NCT02528188), patients received subcutaneous tanezumab 2.5 mg or 5 mg every 8 weeks or daily oral nonsteroidal anti-inflammatory drugs (NSAID) for 56 weeks. The co-primary efficacy endpoints were change from baseline in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain subscale score and WOMAC Physical Function subscale score at Week 16 (overall study and Japan-specific endpoints) as well as Patient Global Assessment (PGA)-OA score at Week 16 (overall study endpoint only). In Study 2 (NCT02709486), patients received subcutaneous tanezumab 2.5 mg, 5 mg, or placebo every 8 weeks for 24 weeks. Safety monitoring included adjudicated composite joint safety endpoint (CJSE) including rapidly progressive osteoarthritis type 1 (RPOA1), RPOA2, primary osteonecrosis, pathological fracture, or subchondral insufficiency fracture.

RESULTS

For Study 1, Japanese patients (n = 200) treated with tanezumab 2.5 mg and 5 mg showed numerically greater improvements in WOMAC Pain, WOMAC Physical Function, and PGA-OA scores versus NSAID at Week 16. Incidences of treatment-emergent adverse events were generally similar between tanezumab 2.5 mg, 5 mg, and NSAID groups. In the integrated safety analysis (Studies 1 + 2; n = 306), ten patients were adjudicated to have a component of CJSE: RPOA1 [tanezumab 2.5 mg (n = 2), tanezumab 5 mg (n = 5)], RPOA2 [tanezumab 2.5 mg (n = 1), tanezumab 5 mg (n = 1)], or primary osteonecrosis [tanezumab 2.5 mg (n = 1)]. Time-adjusted adjudicated rates of RPOA1 and RPOA2 were higher with tanezumab than NSAID or placebo and increased with dose of tanezumab.

CONCLUSION

Observations from the Japanese subgroup were generally consistent with the overall study populations.

The expression of nerve growth factor in healthy and inflamed equine chondrocytes analysed by capillary western immunoassay

Nerve Growth Factor (NGF) is a signalling molecule for pain and inflammation. NGF is increased in synovial fluid from osteoarthritic humans and animals, compared to healthy controls. Monoclonal antibody therapy directed against NGF has been approved to treat pain in osteoarthritic dogs but despite many years of trialling, therapy has not been approved for human use. One reason for this is that adverse reactions with rapidly progressing osteoarthritis has occurred in some individuals. More detailed knowledge of NGF expression in joints is needed. In this study, capillary-based Simple Western was used to analyse NGF in cultured equine chondrocytes. Chondrocytes were collected post mortem from three macroscopically healthy intercarpal joints and three intercarpal joints with mild osteoarthritic changes. The chondrocytes were expanded to passage one and seeded in chondrogenic medium to maintain the phenotype. On day four, cells were either stimulated with LPS or kept untreated in medium. All cells were harvested on day five. Wes analysis of lysates did not show mature NGF but two proforms, 40 and 45 kDa, were identified. Results were confirmed with western blot. The same proforms were expressed in chondrocytes from healthy and osteoarthritic joints. Acute inflammation induced by LPS stimulation did not change the forms of expressed NGF. Capillary Simple Western offers a sensitive and sample-sparing alternative to traditional western blot. However, confirmation of peaks is imperative in order to avoid misinterpretation of findings. In addition, in this case the method did not offer the possibility of quantification advertised by the manufacturers.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICALTRIALS

gov: NCT02528253.

Network Pharmacology-Based Strategy to Investigate the Mechanisms of Cibotium barometz in Treating Osteoarthritis

Cibotium barometz is a representative tonifying kidney drug and is widely used for osteoarthritis (OA) in traditional Chinese medicine. However, its regulatory mechanisms in treating OA remain to be sufficiently investigated. The main chemical components of Cibotium barometz were screened through the TCMID database and the corresponding targets were acquired through SwissTargetPrediction. The OA-related targets were obtained from the OMIM, Genecards, Genebank, TTD, and DisGeNET databases. The prediction of key targets and pathways of Cibotium barometz in the treatment of OA was achieved by constructing a compounds-targets network and performing KEGG enrichment analysis. The OA model rats were established by the Hulth method and used to explore the protective effect of Cibotium barometz via cartilage pathological assessment. In vitro models of OA were built by the proinflammatory factor interleukin-1β (IL-1β) induced SW1353 cells and used to validate the mechanisms predicted by network pharmacology. Network pharmacology results suggested that the therapeutic effects of Cibotium barometz were closely related to matrix metalloproteinase (MMP)-1, 3, 13 and inflammation-related gene COX2, which are regulated by the NFκB pathway. In vivo experiments revealed that Cibotium barometz could effectively restrain cartilage from degeneration and inhibit the mRNA expression of MMP-1, MMP-3, MMP-13, and COX2 in cartilage. In vitro experiments indicated that Cibotium barometz water extract (CBWE) could significantly inhibit the expression of MMP-1, MMP-3, MMP-13, and PGE₂ in IL-1β-induced SW1353 cells and markedly prevent the translocation of NFκB p65 from the cytoplasm to the nuclei and decrease its phosphorylation level. After small-interfering RNA (siRNA) was used to suppress the synthesis of NFκB p65 to block NFκB signaling pathway, the ability of CBWE to inhibit MMP-1, MMP-3, MMP-13, and PGE₂ was greatly reduced. Cibotium barometz has a chondroprotective effect on OA by inhibiting the response to inflammation and substrate degradation, and the related mechanism is associated with the inhibition of the NFκB pathway.

WOMAC Meaningful Within-patient Change: Results From 3 Studies of Tanezumab in Patients With Moderate-to-severe Osteoarthritis of the Hip or Knee

OBJECTIVE

To define meaningful within-patient change (MWPC) in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

METHODS

Data were analyzed separately from 3 phase III clinical trials (ClinicalTrials.gov: NCT02697773, NCT02709486, NCT02528188) of tanezumab, a novel treatment intended for the relief of signs and symptoms of moderate-to-severe osteoarthritis (OA), administered subcutaneously every 8 weeks. Patients with moderate-to-severe OA of the hip or knee completed the WOMAC and patient global assessment of OA (PGA-OA) at regular timepoints. A repeated measures longitudinal model with change in WOMAC Pain, Physical Function, or Stiffness domain score as the outcome and change in PGA-OA as the anchor was used to establish MWPC for WOMAC domains.

RESULTS

In the 3 studies, there were 688, 844, and 2948 subjects available for analyses, respectively. Analysis showed that a linear relationship between changes in WOMAC domains and changes in PGA-OA was supported and justified. Moreover, the relationships between these changes were very similar for 2 trials and close for the third. The estimated MWPC for the 3 WOMAC domains were from 0.84-1.16 (0-10 numerical rating scale) and from 12.50-16.23%, depending on study and domain, that corresponded to a 1-category change on PGA-OA. For a 2-category change those values were from 1.68-2.31 and from 25.01-32.46%, respectively.

CONCLUSION

These results establish MWPCs for WOMAC domains, at the individual patient level, for patients with moderate-to-severe OA of the hip or knee. [ClinicalTrials.gov: NCT02697773, NCT02709486, and NCT02528188].

The Hunt Is On! In Pursuit of the Ideal Stem Cell Population for Cartilage Regeneration

Cartilage injury and degeneration are hallmarks of osteoarthritis (OA), the most common joint disease. OA is a major contributor to pain, loss of function, and reduced quality of life. Over the last decade, considerable research efforts have focused on cell-based therapies, including several stem cell-derived approaches to reverse the cartilage alterations associated with OA. Although several tissue sources for deriving cell-based therapies have been identified, none of the resident stem cell populations have adequately fulfilled the promise of curing OA. Indeed, many cell products do not contain true stem cells. As well, issues with aggressive marketing efforts, combined with a lack of evidence regarding efficacy, lead the several national regulatory bodies to discontinue the use of stem cell therapy for OA until more robust evidence becomes available. A review of the evidence is timely to address the status of cell-based cartilage regeneration. The promise of stem cell therapy is not new and has been used successfully to treat non-arthritic diseases, such as hematopoietic and muscle disorders. These fields of regenerative therapy have the advantage of a considerable foundation of knowledge in the area of stem cell repair mechanisms, the role of the stem cell niche, and niche-supporting cells. This foundation is lacking in the field of cartilage repair. So, where should we look for the ideal stem cell to regenerate cartilage? It has recently been discovered that cartilage itself may contain a population of SC-like progenitors. Other potential tissues include stem cell-rich dental pulp and the adolescent growth plate, the latter of which contains chondrocyte progenitors essential for producing the cartilage scaffold needed for bone growth. In this article, we review the progress on stem cell therapies for arthritic disorders, focusing on the various stem cell populations previously used for cartilage regeneration, successful cases of stem cell therapies in muscle and hemopoietic disorders, some of the reasons why these other fields have been successful (i.e., "lessons learned" to be applied to OA stem cell therapy), and finally, novel potential sources of stem cells for regenerating damaged cartilage in vivo.

Localization of Nerve Growth Factor Expression to Structurally Damaged Cartilaginous Tissues in Human Lumbar Facet Joint Osteoarthritis

Purpose

Nerve Growth Factor (NGF) is a pivotal mediator of chronic pain and plays a role in bone remodelling. Through its high affinity receptor TrkA, NGF induces substance P (SP) as key downstream mediator of pain and local inflammation. Here we analysed NGF, TrkA and SP tissue distribution in facet joint osteoarthritis (FJOA), a major cause of chronic low back pain.

Methods

FJOA specimens (n=19) were harvested from patients undergoing intervertebral fusion surgery. Radiologic grading of FJOA and spinal stenosis, followed by immunohistochemistry for NGF, TrkA and SP on consecutive tissue sections, was performed in ten specimens. Explant cultures (n=9) were used to assess secretion of NGF, IL-6, and SP by FJOA osteochondral tissues under basal and inflammatory conditions.

Results

NGF was predominantly expressed in damaged cartilaginous tissues (80%), occasionally in bone marrow (20%), but not in osteochondral vascular channels. NGF area fraction in cartilage was not associated with the extent of proteoglycan loss or radiologic FJOA severity. Consecutive sections showed that NGF and SP expression was localized at structurally damaged cartilage, in absence of TrkA expression. SP and TrkA were expressed in subchondral bone marrow in both presence and absence of NGF. Low level NGF, but not SP secretion, was detected in four out of eighteen FJOA explants under both basal or inflammatory conditions (n=2 each).

Conclusion

NGF is associated with SP expression and structural cartilage damage in osteoarthritic facet joints, but not with radiologic disease severity. NGF tissue distribution in FJOA differs from predominant subchondral bone expression reported for knee OA.

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; I² = 38%), WOMAC physical function (−0.36 [95% CI, –0.41 to –0.30]; Z = 12.67; P < .001; I² = 44%), WOMAC stiffness (–3.59 [95% CI, –4.87 to –2.30]; Z = 5.47; P < .001; I² = 98%), and PGA (−0.28 [95% CI, –0.34 to –0.22]; Z = 9.39; P < .001; I² = 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; I² = 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; I² = 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.

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.

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.

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.

Observed efficacy and clinically important improvements in participants with osteoarthritis treated with subcutaneous tanezumab: results from a 56-week randomized NSAID-controlled study

BACKGROUND

A recent phase 3 study demonstrated that treatment with tanezumab, a nerve growth factor inhibitor, or nonsteroidal anti-inflammatory drugs (NSAIDs) improves pain and physical function in participants with moderate-to-severe osteoarthritis (OA) of the hip or knee. Here, we evaluated the time course and clinical importance of these initial efficacy findings using a mixture of primary, secondary, and post hoc endpoints.

METHODS

Participants on stable NSAID therapy and with a history of inadequate response to other standard OA analgesics were enrolled in an 80-week (56-week treatment/24-week safety follow-up), randomized, NSAID-controlled, phase 3 study primarily designed to assess the safety of tanezumab for moderate-to-severe OA of the knee or hip. Participants received oral NSAID (twice daily naproxen, celecoxib, or diclofenac) or subcutaneous tanezumab (2.5mg or 5mg every 8 weeks). Non-responders were discontinued at week 16. Changes from baseline in WOMAC Pain and Physical Function, Patient's Global Assessment of Osteoarthritis (PGA-OA), and average pain in the index joint were compared between tanezumab and NSAID groups over the 56-week treatment period. Clinically meaningful response (e.g., ≥30% and ≥50% improvement in WOMAC Pain and Physical Function), rescue medication use, and safety were also assessed.

RESULTS

All groups improved WOMAC Pain, WOMAC Physical Function, PGA-OA, and average pain in the index joint over the 56-week treatment period relative to baseline. Across all groups, improvements generally occurred from the time of first assessment (week 1 or 2) to week 16 and then slightly decreased from week 16 to 24 before stabilizing from weeks 24 to 56. The magnitude of improvement and the proportion of participants achieving ≥30% and ≥50% improvement in these measures was greater (unadjusted p≤0.05) with tanezumab than with NSAID at some timepoints on or before week 16. Adverse events of abnormal peripheral sensation, prespecified joint safety events, and total joint replacement surgery occurred more frequently with tanezumab than with NSAID.

CONCLUSIONS

Tanezumab and NSAID both provided early and sustained (up to 56 weeks) efficacy relative to baseline. Improvements in pain and function were clinically meaningful in a substantial proportion of participants. Adverse events of abnormal peripheral sensation and joint safety events occurred more frequently with tanezumab than with NSAID.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02528188 . Registered on 19 July 2015.

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.

Exploring patient preference heterogeneity for pharmacological treatments for chronic pain: A latent class analysis

BACKGROUND

Several pharmaceutical treatments for chronic pain caused by osteoarthritis (OA) and chronic low back pain (CLBP) are available or currently under development, each associated with different adverse events (AEs) and efficacy profiles. It is therefore important to understand what trade-offs patients are willing to make when choosing between treatments.

METHODS

A discrete-choice experiment (DCE) was conducted with 437 adults with chronic pain caused by OA and/or CLBP. Respondents were presented with a series of scenarios and asked to choose between pairs of hypothetical treatments, each defined by six attributes: level of symptom control; risks of heart attack, rapidly progressive osteoarthritis and dependency; frequency and mode of administration and cost. Attributes were based on known profiles of oral nonsteroidal anti-inflammatory drugs, opioids and injected nerve growth factor inhibitors, the last of which were under clinical development at the time of the study. Data were analysed using a latent class (LC) model to explore preference heterogeneity.

RESULTS

Overall, respondents considered improving symptom control and reducing risk of physical dependency to be the most important attributes. The LC analysis identified four participant classes: an 'efficacy-focused' class (33.7%), a 'cost-averse' class (29.4%), a 'physical-dependence-averse' class (19.6%) and a 'needle-averse' class (17.3%). Subgroup membership was incompletely predicted by participant age and their responses to comprehension questions.

CONCLUSIONS

Preference heterogeneity across respondents indicates a need for a personalized approach to offering treatment options. Symptom improvement, cost, physical dependence and route of administration might be important to different patients.

SIGNIFICANCE

Multiple treatment options that differ substantially in terms of efficacy and adverse events are available for the management of chronic pain. With a growing emphasis on a patient-centred care model that incorporates patients' priorities and values into treatment decisions, there is a need to understand how individuals with chronic musculoskeletal pain balance the benefits and risks of treatment and how treatment priorities vary among individuals. This study was designed to identify patient preferences for different characteristics of treatments for the management of chronic pain and to investigate how preferences differ among respondents.

Impact of tanezumab on health status, non-work activities and work productivity in adults with moderate-to-severe osteoarthritis

BACKGROUND

To evaluate the impact of tanezumab on health status, non-work activities, and work productivity in a pooled analysis of two large phase 3 osteoarthritis (OA) studies.

METHODS

Subcutaneous tanezumab (2.5 mg and 5 mg) was tested in double-blind, placebo-controlled, 16-week (NCT02697773) and 24-week (NCT02709486) clinical trials in patients with moderate-to-severe OA of the hip or knee. At baseline and week 16, all patients completed EQ-5D-5L and the Work Productivity and Activity Impairment-OA (WPAI-OA) activity impairment item. Those currently employed also completed WPAI-OA work time missed, impairment while working, and overall work impairment items. Between-group differences in least squares (LS) mean changes from baseline at week 16 were tested using analysis of covariance.

RESULTS

Of 1545 pooled patients, 576 were employed at baseline. Improvements in EQ-5D-5L index value at week 16 were significantly greater for the tanezumab 2.5-mg group (difference in LS means [95% confidence interval (CI), 0.03 [0.01, 0.05]; p = 0.0083) versus placebo. Percent improvements (95% CI) in activity impairment (- 5.92 [- 8.87, - 2.98]; p < 0.0001), impairment while working (- 7.34 [- 13.01, - 1.68]; p = 0.0112), and overall work impairment (- 7.44 [- 13.22, - 1.67]; p = 0.0116) at week 16 were significantly greater for the tanezumab 2.5-mg group versus placebo. Results for the tanezumab 5-mg group were generally comparable to the tanezumab 2.5-mg group, although, compared with placebo, percent improvement (95% CI) in work time missed was significantly greater for the tanezumab 5-mg group (- 3.40 [- 6.47, - 0.34]; p = 0.0294), but not the tanezumab 2.5-mg group (- 0.66 [- 3.63, 2.32]; p = 0.6637).

CONCLUSIONS

These pooled analyses showed that health status, non-work activities, and work productivity were significantly improved following tanezumab administration, compared with placebo.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02697773, NCT02709486.