Safety, Tolerability, and Pharmacodynamics of the ADAMTS-5 Nanobody M6495: Two Phase 1, Single-Center, Double-Blind, Randomized, Placebo-Controlled Studies in Healthy Subjects and Patients With Osteoarthritis

OBJECTIVE

To assess the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of single and multiple injections of M6495, a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5)  nanobody, in healthy volunteers and patients with osteoarthritis.

METHODS

Two randomized, placebo-controlled, double-blind studies were performed. Study 1 enrolled 54 healthy male volunteers who received one subcutaneous (s.c.) injection of M6495 (1-300 mg) or placebo (ratio 2:1), evaluating safety, PK, and PD as changes in the serum aggrecan fragment alanine-arginine-glycine-serine (ARGS). Study 2 enrolled 32 patients with osteoarthritis with Kellgren-Lawrence grades 2 to 4 and pain greater than or equal to 40 on the Western Ontario and McMaster Universities Arthritis Index pain subscale at screening and evaluated the safety, PK, and PD of three doses every two weeks (75-300 mg per dose) or six once-weekly M6495 s.c. doses (300 mg) or placebo (ratio 3:1) over 106 days' follow-up.

RESULTS

M6495 in single and multiple doses of less than or equal to 300 mg s.c. weekly was well tolerated with no clinically significant changes in any safety parameter. Adverse events more frequently reported in the M6495 groups were mostly mild cases of injection site reactions, myalgia, and nausea, which resolved after treatment cessation. The elimination half-life of single s.c. doses of M6495 ranged from 79 to 267 hours. M6495 administration substantially reduced serum ARGS levels, indicative of target engagement and indicating disease-modifying potential of M6495.

CONCLUSION

Treatment with M6495 in single and multiple doses up to and including 300 mg s.c. was found to be well tolerated and adequately safe for further clinical evaluation of potential disease-modifying effects.

Association of biochemical markers with bone marrow lesion changes on imaging-data from the Foundation for the National Institutes of Health Osteoarthritis Biomarkers Consortium

BACKGROUND

To assess the prognostic value of short-term change in biochemical markers as it relates to bone marrow lesions (BMLs) on MRI in knee osteoarthritis (OA) over 24 months and, furthermore, to assess the relationship between biochemical markers involved with tissue turnover and inflammation and BMLs on MRI.

METHODS

Data from the Foundation for the National Institutes of Health OA Biomarkers Consortium within the Osteoarthritis Initiative (n = 600) was analyzed. BMLs were measured according to the MRI Osteoarthritis Knee Score (MOAKS) system (0-3), in 15 knee subregions. Serum and urinary biochemical markers assessed were as follows: serum C-terminal crosslinked telopeptide of type I collagen (CTX-I), serum crosslinked N-telopeptide of type I collagen (NTX-I), urinary CTX-Iα and CTX-Iβ, urinary NTX-I, urinary C-terminal cross-linked telopeptide of type II collagen (CTX-II), serum matrix metalloproteinase (MMP)-degraded type I, II, and III collagen (C1M, C2M, C3M), serum high sensitivity propeptide of type IIb collagen (hsPRO-C2), and matrix metalloproteinase-generated neoepitope of C-reactive protein (CRPM). The association between change in biochemical markers over 12 months and BMLs over 24 months was examined using regression models adjusted for covariates. The relationship between C1M, C2M, C3M, hsPRO-C2, and CRPM and BMLs at baseline and over 24 months was examined.

RESULTS

Increases in serum CTX-I and urinary CTX-Iβ over 12 months were associated with increased odds of changes in the number of subregions affected by any BML at 24 months. Increase in hsPRO-C2 was associated with decreased odds of worsening in the number of subregions affected by any BML over 24 months. C1M and C3M were associated with BMLs affected at baseline.

CONCLUSIONS

Short-term changes in serum CTX-I, hsPRO-C2, and urinary CTX-Iβ hold the potential to be prognostic of BML progression on MRI. The association of C1M and C3M with baseline BMLs on MRI warrants further investigation.

From biochemical markers to molecular endotypes of osteoarthritis: a review on validated biomarkers

INTRODUCTION

Osteoarthritis (OA) affects over 500 million people worldwide. OA patients are symptomatically treated, and current therapies exhibit marginal efficacy and frequently carry safety-risks associated with chronic use. No disease-modifying therapies have been approved to date leaving surgical joint replacement as a last resort. To enable effective patient care and successful drug development there is an urgent need to uncover the pathobiological drivers of OA and how these translate into disease endotypes. Endotypes provide a more precise and mechanistic definition of disease subgroups than observable phenotypes, and a panel of tissue- and pathology-specific biochemical markers may uncover treatable endotypes of OA.

AREAS COVERED

We have searched PubMed for full-text articles written in English to provide an in-depth narrative review of a panel of validated biochemical markers utilized for endotyping of OA and their association to key OA pathologies.

EXPERT OPINION

As utilized in IMI-APPROACH and validated in OAI-FNIH, a panel of biochemical markers may uncover disease subgroups and facilitate the enrichment of treatable molecular endotypes for recruitment in therapeutic clinical trials. Understanding the link between biochemical markers and patient-reported outcomes and treatable endotypes that may respond to given therapies will pave the way for new drug development in OA.

Development and validation of a machine learning-supported strategy of patient selection for osteoarthritis clinical trials: the IMI-APPROACH study

Objectives

To efficiently assess the disease-modifying potential of new osteoarthritis treatments, clinical trials need progression-enriched patient populations. To assess whether the application of machine learning results in patient selection enrichment, we developed a machine learning recruitment strategy targeting progressive patients and validated it in the IMI-APPROACH knee osteoarthritis prospective study.

Design

We designed a two-stage recruitment process supported by machine learning models trained to rank candidates by the likelihood of progression. First stage models used data from pre-existing cohorts to select patients for a screening visit. The second stage model used screening data to inform the final inclusion. The effectiveness of this process was evaluated using the actual 24-month progression.

Results

From 3500 candidate patients, 433 with knee osteoarthritis were screened, 297 were enrolled, and 247 completed the 2-year follow-up visit. We observed progression related to pain (P, 30%), structure (S, 13%), and combined pain and structure (P ​+ ​S, 5%), and a proportion of non-progressors (N, 52%) ∼15% lower vs an unenriched population. Our model predicted these outcomes with AUC of 0.86 [95% CI, 0.81-0.90] for pain-related progression and AUC of 0.61 [95% CI, 0.52-0.70] for structure-related progression. Progressors were ranked higher than non-progressors for P ​+ ​S (median rank 65 vs 143, AUC = 0.75), P (median rank 77 vs 143, AUC = 0.71), and S patients (median rank 107 vs 143, AUC = 0.57).

Conclusions

The machine learning-supported recruitment resulted in enriched selection of progressive patients. Further research is needed to improve structural progression prediction and assess this strategy in an interventional trial.

Quantitative measurement of cartilage morphology in osteoarthritis: current knowledge and future directions

Quantitative measures of cartilage morphology ("cartilage morphometry") extracted from high resolution 3D magnetic resonance imaging (MRI) sequences have been shown to be sensitive to osteoarthritis (OA)-related change and also to treatment interventions. Cartilage morphometry is therefore nowadays widely used as outcome measure for observational studies and randomized interventional clinical trials. The objective of this narrative review is to summarize the current status of cartilage morphometry in OA research, to provide insights into aspects relevant for the design of future studies and clinical trials, and to give an outlook on future developments. It covers the aspects related to the acquisition of MRIs suitable for cartilage morphometry, the analysis techniques needed for deriving quantitative measures from the MRIs, the quality assurance required for providing reliable cartilage measures, and the appropriate participant recruitment criteria for the enrichment of study cohorts with knees likely to show structural progression. Finally, it provides an overview over recent clinical trials that relied on cartilage morphometry as a structural outcome measure for evaluating the efficacy of disease-modifying OA drugs (DMOAD).

Reflections from the OARSI 2022 clinical trials symposium: The pain of OA-Deconstruction of pain and patient-reported outcome measures for the benefit of patients and clinical trial design

OBJECTIVE

Osteoarthritis (OA) drug development is hampered by a number of challenges. One of the main challenges is the apparent discordance between pain and structure, which has had a significant impact on drug development programs and has led to hesitance among stakeholders. Since 2017, the Clinical Trials Symposium (CTS) has been hosted under the Osteoarthritis Research Society International (OARSI) leadership. OARSI and the CTS steering committee yearly invite and encourage discussions on selected special subject matter between regulators, drug developers, clinicians, clinical researchers, biomarker specialists, and basic scientists to progress drug development in the OA field.

METHOD

The main topic for the 2022 OARSI CTS was to elucidate the many facets of pain in OA and to enable a discussion between regulators (Food and Drug Administration (FDA) and the European Medicines Agency (EMA)) and drug developers to clarify outcomes and study designs for OA drug development.

RESULTS

Signs or symptoms indicative of nociceptive pain occur in 50-70% of OA patients, neuropathic-like pain in 15-30% of patients, and nociplastic pain in 15-50% of patients. Weight-bearing knee pain is associated with bone marrow lesions and effusions. There are currently no simple objective functional tests whose improvements correlate with patient perceptions.

CONCLUSIONS

The CTS participants, in collaboration with the FDA and EMA, raised several suggestions that they consider key to future clinical trials in OA including the need for more precise differentiation of pain symptoms and mechanisms, and methods to reduce placebo responses in OA trials.

Predicted and actual 2-year structural and pain progression in the IMI-APPROACH knee osteoarthritis cohort

OBJECTIVES

The IMI-APPROACH knee osteoarthritis study used machine learning (ML) to predict structural and/or pain progression, expressed by a structural (S) and pain (P) predicted-progression score, to select patients from existing cohorts. This study evaluates the actual 2-year progression within the IMI-APPROACH, in relation to the predicted-progression scores.

METHODS

Actual structural progression was measured using minimum joint space width (minJSW). Actual pain (progression) was evaluated using the Knee injury and Osteoarthritis Outcomes Score (KOOS) pain questionnaire. Progression was presented as actual change (Δ) after 2 years, and as progression over 2 years based on a per patient fitted regression line using 0, 0.5, 1 and 2-year values. Differences in predicted-progression scores between actual progressors and non-progressors were evaluated. Receiver operating characteristic (ROC) curves were constructed and corresponding area under the curve (AUC) reported. Using Youden's index, optimal cut-offs were chosen to enable evaluation of both predicted-progression scores to identify actual progressors.

RESULTS

Actual structural progressors were initially assigned higher S predicted-progression scores compared with structural non-progressors. Likewise, actual pain progressors were assigned higher P predicted-progression scores compared with pain non-progressors. The AUC-ROC for the S predicted-progression score to identify actual structural progressors was poor (0.612 and 0.599 for Δ and regression minJSW, respectively). The AUC-ROC for the P predicted-progression score to identify actual pain progressors were good (0.817 and 0.830 for Δ and regression KOOS pain, respectively).

CONCLUSION

The S and P predicted-progression scores as provided by the ML models developed and used for the selection of IMI-APPROACH patients were to some degree able to distinguish between actual progressors and non-progressors.

TRIAL REGISTRATION

ClinicalTrials.gov, https://clinicaltrials.gov, NCT03883568.

Animal Models of Osteoarthritis Part 1-Preclinical Small Animal Models: Challenges and Opportunities for Drug Development

Osteoarthritis (OA) is the most common form of arthritis and a major source of pain and disability in the adult population. There is a significant unmet medical need for the development of effective pharmacological therapies for the treatment of OA. In addition to spontaneously occurring animal models of OA, many experimental animal models have been developed to provide insights into mechanisms of pathogenesis and progression. Many of these animal models are also being used in the drug development pipeline. Here, we provide an overview of commonly used and emerging preclinical small animal models of OA and highlight the strengths and limitations of small animal models in the context of translational drug development. There is limited information in the published literature regarding the technical reliability of these small animal models and their ability to accurately predict clinical drug development outcomes. The cost and complexity of the available models however is an important consideration for pharmaceutical companies, biotechnology startups, and contract research organizations wishing to incorporate preclinical models in target validation, discovery, and development pipelines. Further considerations relevant to industry include timelines, methods of induction, the key issue of reproducibility, and appropriate outcome measures needed to objectively assess outcomes of experimental therapeutics. Preclinical small animal models are indispensable tools that will shine some light on the pathogenesis of OA and its molecular endotypes in the context of drug development. This paper will focus on small animal models used in preclinical OA research. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC.

Osteoarthritis endotype discovery via clustering of biochemical marker data

OBJECTIVES

Osteoarthritis (OA) patient stratification is an important challenge to design tailored treatments and drive drug development. Biochemical markers reflecting joint tissue turnover were measured in the IMI-APPROACH cohort at baseline and analysed using a machine learning approach in order to study OA-dominant phenotypes driven by the endotype-related clusters and discover the driving features and their disease-context meaning.

METHOD

Data quality assessment was performed to design appropriate data preprocessing techniques. The k-means clustering algorithm was used to find dominant subgroups of patients based on the biochemical markers data. Classification models were trained to predict cluster membership, and Explainable AI techniques were used to interpret these to reveal the driving factors behind each cluster and identify phenotypes. Statistical analysis was performed to compare differences between clusters with respect to other markers in the IMI-APPROACH cohort and the longitudinal disease progression.

RESULTS

Three dominant endotypes were found, associated with three phenotypes: C1) low tissue turnover (low repair and articular cartilage/subchondral bone turnover), C2) structural damage (high bone formation/resorption, cartilage degradation) and C3) systemic inflammation (joint tissue degradation, inflammation, cartilage degradation). The method achieved consistent results in the FNIH/OAI cohort. C1 had the highest proportion of non-progressors. C2 was mostly linked to longitudinal structural progression, and C3 was linked to sustained or progressive pain.

CONCLUSIONS

This work supports the existence of differential phenotypes in OA. The biomarker approach could potentially drive stratification for OA clinical trials and contribute to precision medicine strategies for OA progression in the future.

TRIAL REGISTRATION NUMBER

NCT03883568.

Neuropathic pain in the IMI-APPROACH knee osteoarthritis cohort: prevalence and phenotyping

Objectives

Osteoarthritis (OA) patients with a neuropathic pain (NP) component may represent a specific phenotype. This study compares joint damage, pain and functional disability between knee OA patients with a likely NP component, and those without a likely NP component.

Methods

Baseline data from the Innovative Medicines Initiative Applied Public-Private Research enabling OsteoArthritis Clinical Headway knee OA cohort study were used. Patients with a painDETECT score ≥19 (with likely NP component, n=24) were matched on a 1:2 ratio to patients with a painDETECT score ≤12 (without likely NP component), and similar knee and general pain (Knee Injury and Osteoarthritis Outcome Score pain and Short Form 36 pain). Pain, physical function and radiographic joint damage of multiple joints were determined and compared between OA patients with and without a likely NP component.

Results

OA patients with painDETECT scores ≥19 had statistically significant less radiographic joint damage (p≤0.04 for Knee Images Digital Analysis parameters and Kellgren and Lawrence grade), but an impaired physical function (p<0.003 for all tests) compared with patients with a painDETECT score ≤12. In addition, more severe pain was found in joints other than the index knee (p≤0.001 for hips and hands), while joint damage throughout the body was not different.

Conclusions

OA patients with a likely NP component, as determined with the painDETECT questionnaire, may represent a specific OA phenotype, where local and overall joint damage is not the main cause of pain and disability. Patients with this NP component will likely not benefit from general pain medication and/or disease-modifying OA drug (DMOAD) therapy. Reserved inclusion of these patients in DMOAD trials is advised in the quest for successful OA treatments.

Trial registration number

The study is registered under clinicaltrials.gov nr: NCT03883568.

Baseline clinical characteristics of predicted structural and pain progressors in the IMI-APPROACH knee OA cohort

OBJECTIVES

To describe the relations between baseline clinical characteristics of the Applied Public-Private Research enabling OsteoArthritis Clinical Headway (IMI-APPROACH) participants and their predicted probabilities for knee osteoarthritis (OA) structural (S) progression and/or pain (P) progression.

METHODS

Baseline clinical characteristics of the IMI-APPROACH participants were used for this study. Radiographs were evaluated according to Kellgren and Lawrence (K&L grade) and Knee Image Digital Analysis. Knee Injury and Osteoarthritis Outcome Score (KOOS) and Numeric Rating Scale (NRS) were used to evaluate pain. Predicted progression scores for each individual were determined using machine learning models. Pearson correlation coefficients were used to evaluate correlations between scores for predicted progression and baseline characteristics. T-tests and χ² tests were used to evaluate differences between participants with high versus low progression scores.

RESULTS

Participants with high S progressions score were found to have statistically significantly less structural damage compared with participants with low S progression scores (minimum Joint Space Width, minJSW 3.56 mm vs 1.63 mm; p<0.001, K&L grade; p=0.028). Participants with high P progression scores had statistically significantly more pain compared with participants with low P progression scores (KOOS pain 51.71 vs 82.11; p<0.001, NRS pain 6.7 vs 2.4; p<0.001).

CONCLUSIONS

The baseline minJSW of the IMI-APPROACH participants contradicts the idea that the (predicted) course of knee OA follows a pattern of inertia, where patients who have progressed previously are more likely to display further progression. In contrast, for pain progressors the pattern of inertia seems valid, since participants with high P score already have more pain at baseline compared with participants with a low P score.

Making the patient voice heard in a research consortium: experiences from an EU project (IMI-APPROACH)

APPROACH is an EU-wide research consortium with the goal to identify different subgroups of knee osteoarthritis to enable future differential diagnosis and treatment. During a 2-year clinical study images, biomarkers and clinical data are collected from people living with knee osteoarthritis and data are analyzed to confirm patterns that can indicate such different subgroups. A Patient Council (PC) has been set up at project initiation and consists of five people from Norway, The Netherlands and UK. Initially, this group of individuals had to learn how to effectively work with each other and with the researchers. Today, the PC is a strong team that is fully integrated in the consortium and acknowledged by researchers as an important sounding board. The article describes this journey looking at formal processes of involvement - organizational structure, budget, meetings - and more informal processes such as building relationships and changing researcher perceptions. It describes how the PC helped improve the experience and engagement of study participants by providing input to the clinical protocol and ensuring effective communication (e.g. through direct interactions with participants and newsletters). Furthermore, the PC is helping with dissemination of results and project advocacy, and overall provides the patient perspective to researchers. Additionally, the authors experienced and describe the intangible benefits such as a shift in researcher attitudes and a sense of community and purpose for PC members. Importantly, learnings reported in this article also include the challenges, such as effective integration of the PC with researchers' work in the early phase of the project. TRIAL REGISTRATION: US National Library of Medicine, NCT03883568 , retrospectively registered 21 March 2019.

Long-term structural and symptomatic effects of intra-articular sprifermin in patients with knee osteoarthritis: 5-year results from the FORWARD study

OBJECTIVE

The FORWARD (FGF-18 Osteoarthritis Randomized Trial with Administration of Repeated Doses) trial assessed efficacy and safety of the potential disease-modifying osteoarthritis drug (DMOAD) sprifermin in patients with knee osteoarthritis. Here, we report 5-year efficacy and safety results.

METHODS

Patients were randomised to intra-articular sprifermin 100 µg or 30 µg every 6 months (q6mo) or 12 months, or placebo, for 18 months. The primary analysis was at year 2, with follow-up at years 3, 4 and 5. Additional post hoc exploratory analyses were conducted in patients with baseline minimum radiographic joint space width 1.5-3.5 mm and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain 40-90, a subgroup at risk (SAR) of progression.

RESULTS

378 (69%) patients completed the 5-year follow-up. A significant dose-response in total femorotibial joint cartilage thickness with sprifermin (trend test, p<0.001) and a 0.05 mm mean difference with sprifermin 100 µg q6mo versus placebo (95% CI 0.00 to 0.10; p=0.015) were sustained to year 5. WOMAC pain scores improved ~50% from baseline in all groups. No patient in the 100 µg q6mo group had replacement of the treated knee. 96%-98% of patients receiving sprifermin and 98% placebo reported adverse events, most were mild or moderate and deemed unrelated to treatment. Adverse event-related study withdrawals were <10%. Differentiation in WOMAC pain between sprifermin 100 µg q6mo and placebo in the SAR (n=161) at year 3 was maintained to year 5 (-10.08; 95% CI -25.68 to 5.53).

CONCLUSION

In the longest DMOAD trial reported to date, sprifermin maintained long-term structural modification of articular cartilage over 3.5 years post-treatment. Potential translation to clinical benefit was observed in the SAR.

TRIAL REGISTRATION NUMBER

NCT01919164.

The effects of sprifermin on symptoms and structure in a subgroup at risk of progression in the FORWARD knee osteoarthritis trial

OBJECTIVE

To assess pain outcomes and cartilage thickness change in a subgroup at risk (SAR) of further progression in the FORWARD trial of knee osteoarthritis patients treated with sprifermin.

METHODS

Patients were randomised 1:1:1:1:1 to: sprifermin 100 µg every 6 months (q6mo), 100 µg q12mo, 30 µg q6mo, 30 µg q12mo, or placebo for 18 months. SAR was defined as baseline medial or lateral minimum joint-space width (mJSW) 1.5-3.5 mm and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score 40-90 units. Follow-up to 3 years was included in the analysis. Treatment benefit was explored by repeated measures, linear dose-effect trends by timepoint.

RESULTS

The SAR comprised 161 (29%) of 549 patients. Mean difference (95% CI) in WOMAC pain at year 3 for sprifermin 100 µg q6mo vs placebo SAR was -8.75 (-22.42, 4.92) for SAR vs 0.97 (-6.22, 8.16) for the intent-to-treat population. SAR placebo patients lost more cartilage over 2 years than the modified ITT (mITT) placebo arm (mean change from baseline, mm [SD]: -0.05 [0.10] vs -0.02 [0.07]). Net total femorotibial joint thickness gain with sprifermin 100 µg q6mo (adjusted mean difference from placebo [95% CI] was similar in the SAR and in the mITT group: 0.06 [0.01, 0.11] vs 0.05 [0.03, 0.07]).

CONCLUSIONS

Selection for low mJSW and moderate-to-high pain at baseline resulted in more rapid disease progression and demonstrated translation of structure modification (with maintained net benefit on total cartilage thickness) into symptomatic benefit. This subgroup may represent a target population for future trials.

CLINICAL TRIAL REGISTRATION

NCT01919164.

Automated MRI assessment confirms cartilage thickness modification in patients with knee osteoarthritis: post-hoc analysis from a phase II sprifermin study

BACKGROUND

Sprifermin is under investigation as a potential disease-modifying osteoarthritis drug. Previously, 2-year results from the FORWARD study showed significant dose-dependent modification of cartilage thickness in the total femorotibial joint (TFTJ), medial and lateral femorotibial compartments (MFTC, LFTC), and central medial and lateral TFTJ subregions, by quantitative magnetic resonance imaging (qMRI) using manual segmentation.

OBJECTIVE

To determine whether qMRI findings from FORWARD could be reproduced by an independent method of automated segmentation using an identical dataset and similar anatomical regions in a post-hoc analysis.

METHOD

Cartilage thickness was assessed at baseline and 6, 12, 18 and 24 months, using automated cartilage segmentation with active appearance models, a supervised machine learning method. Images were blinded for treatment and timepoint. Treatment effect was assessed by observed and adjusted changes using a linear mixed model for repeated measures.

RESULTS

Based on automated segmentation, statistically significant, dose-dependent structural modification of cartilage thickness was observed over 2 years with sprifermin vs placebo for TFTJ (overall treatment effect and dose response, both P < 0.001), MFTC (P = 0.004 and P = 0.044), and LFTC (both P < 0.001) regions. For highest dose, in the central medial tibial (P = 0.008), central lateral tibial (P < 0.001) and central lateral femoral (P < 0.001) regions.

CONCLUSIONS

Cartilage thickness assessed by automated segmentation provided a consistent dose response in structural modification compared with manual segmentation. This is the first time that two independent quantification methods of image analysis have reached the same conclusions in an interventional trial, strengthening the conclusions that sprifermin modifies structural progression in knee osteoarthritis.

OP0189 ASSESSMENT OF CARTILAGE DEGRADATION AND PROTECTIVE MARKERS IN SYNOVIAL FLUID FROM OSTEOARTHRITIS PATIENTS BEFORE AND AFTER CYCLES OF INTRA-ARTICULAR INJECTIONS WITH SPRIFERMIN

Background:

It is challenging to monitor treatment effects after intra-articular (IA) injection with tissue modifying drugs. Assessment of biomarker levels in synovial fluid may be one solution to the challenge. Sprifermin is a truncated form of fibroblast growth factor (FGF) 18 known to induce chondrocyte proliferation and type II collagen formation [1,2]. Data from preclinical investigations show that cartilage formation happens in different phases after therapy with sprifermin, starting with a phase of cartilage degradation during the induction of proliferation of chondrocytes followed by a phase of cartilage formation/production of extracellular matrix.

Objectives:

The aim was to investigate the effect of IA administrated sprifermin on cartilage turnover activity as compared to placebo in the injected joint by measurement of markers using longitudinal synovial fluid samples of patients participating in the FORWARD study.

Methods:

Each included patient had baseline and at least one FU sample available. Synovial fluid (SF) from participants receiving injections at three consecutive weeks in six month intervals through to week (wk) 80 (fig.A) available from the phase II clinical trial evaluating the efficacy and safety of intraarticularly delivered sprifermin [3] were selected for the investigations. Biochemical markers were measured in available SF samples of the placebo (containing saline IA, n=38) and the highest sprifermin dose group (100 mcg/IAx4, n=59). Samples were pretreated with ultrasound and centrifugation to decrease viscosity. Markers measured were PRO-C2 (type II collagen formation), huARGS (aggrecan degradation), and FBN-C (fibronectin). Markers are technically validated for synovial fluid measurement. Data were individually normalized to baseline to investigate the median proportional change over time.

Results:

Baseline mean (SD) levels of the markers in SF at BL were: PRO-C2, 21.4 (13.6) ng/mL, huARGS, 1117 (516) pM and FBN-C, 2556 (1959) ng/mL. PRO-C2 was initially decreased (from BL to wk 2) after injection with sprifermin; however, the level was increased at the beginning of each new injection cycle followed by a decrease after injection of sprifermin (Fig.B). Overall synovial PRO-C2 levels increased over time in therapy with sprifermin, while no change was observed for the placebo arm. huARGS showed a similar pattern as PRO-C2 – there was an overall increase in ARGS over time in the sprifermin group (fig.C). Interestingly ARGS continuously decreased over time in the placebo group. FBN-C is continuously increased after injection’s cycles, whereas no effect was seen in the placebo group (fig.D).

Conclusion:

Confirmatory of the preclinical investigations a biphasic response on cartilage turnover after injection with sprifermin was observed. Biochemical indications of cartilage formation and chondrocyte proliferation was only modulated in the sprifermin group, and cartilage degradation (ARGS) was temporal induced and reduced by sprifermin and placebo injections, respectively.

References:

[1]Gigout A, et al. “Sprifermin (rhFGF18) enables proliferation of chondrocytes producing a hyaline cartilage matrix”. Osteoarthr Cartil. 2017;25.

[2]Reker D, et al. “Sprifermin (rhFGF18) modulates extracellular matrix turnover in cartilage explants ex vivo”. J Transl Med. 2017;15.

[3]Hochberg MC, et al. “Effect of Intra-Articular Sprifermin vs Placebo on Femorotibial Joint Cartilage Thickness in Patients With Osteoarthritis”. JAMA. 2019; Oct 8;322(14).

Disclosure of Interests:

Anne-Christine Bay-Jensen Shareholder of: Nordic Bioscience A/S, Employee of: Full time employee at Nordic Bioscience A/S., Angela Manginelli Employee of: Merck KGaA, Flavie Moreau Employee of: Merck KGaA, Yi He Employee of: YH is a full time employee of Nordic Bioscience A/S, Yunyun Luo Employee of: Nordic Bioscience A/S, Jeppe Ragnar Andersen Shareholder of: Nordic Bioscience A/S., Employee of: Full time employee of Nordic Bioscience., Asger Reinstrup Bihlet Shareholder of: Nordic Bioscience A/S., Morten Karsdal Shareholder of: Nordic Bioscience A/S., Employee of: Full time employee at Nordic Bioscience A/S., Hans Gühring Employee of: Merck KGaA, Christoph Ladel Employee of: Merck KGaA

Inflammation and joint destruction may be linked to the generation of cartilage metabolites of ADAMTS-5 through activation of toll-like receptors

OBJECTIVE

Links between pain and joint degradation are poorly understood. We investigated the role of activation of Toll-like receptors (TLR) by cartilage metabolites in initiating and maintaining the inflammatory loop in OA causing joint destruction.

METHODS

Synovial membrane explants (SMEs) were prepared from OA patients' synovial biopsies. SMEs were cultured for 10 days under following conditions: culture medium alone, OSM + TNFα, TLR2 agonist - Pam2CSK4, Pam3CSK4 or synthetic aggrecan 32-mer, TLR4 agonist - Lipid A. Release of pro-inflammatory and degradation biomarkers (acMMP3 and C3M) were measured by ELISA in conditioned media along with IL-6. Additionally, human cartilage was digested with ADAMTS-5, with or without the ADAMTS-5 inhibiting nanobody - M6495. Digested cartilage solution (DCS) and synthetic 32-mer were tested for TLR activation in SEAP based TLR reporter assay.

RESULTS

Western blotting confirmed TLR2 and TLR4 in untreated OA synovial biopsies. TLR agonists showed an increase in release of biomarkers - acMMP3 and C3M in SME. Synthetic 32-mer showed no activation in the TLR reporter assay. ADAMTS-5 degraded cartilage fragments activated TLR2 in vitro. Adding M6495 - an anti-ADAMTS-5 inhibiting nanobody®, blocked ADAMTS-5-mediated DCS TLR2 activation.

CONCLUSION

TLR2 is expressed in synovium of OA patients and their activation by synthetic ligands causes increased tissue turnover. ADAMTS-5-mediated cartilage degradation leads to release of aggrecan fragments which activates the TLR2 receptor in vitro. M6495 suppressed cartilage degradation by ADAMTS-5, limiting the activation of TLR2. In conclusion, pain and joint destruction may be linked to generation of ADAMTS-5 cartilage metabolites.

A Novel High Sensitivity Type II Collagen Blood-Based Biomarker, PRO-C2, for Assessment of Cartilage Formation

N-terminal propeptide of type II collagen (PIINP) is a biomarker reflecting cartilage formation. PIINP exists in two main splice variants termed as type IIA and type IIB collagen NH₂-propeptide (PIIANP, PIIBNP). PIIANP has been widely recognized as a cartilage formation biomarker. However, the utility of PIIBNP as a marker in preclinical and clinical settings has not been fully investigated yet. In this study, we aimed to characterize an antibody targeting human PIIBNP and to develop an immunoassay assessing type II collagen synthesis in human blood samples. A high sensitivity electrochemiluminescence immunoassay, hsPRO-C2, was developed using a well-characterized antibody against human PIIBNP. Human cartilage explants from replaced osteoarthritis knees were cultured for ten weeks in the presence of growth factors, insulin-like growth factor 1 (IGF-1) or recombinant human fibroblast growth factor 18 (rhFGF-18). The culture medium was changed every seven days, and levels of PIIBNP, PIIANP, and matrix metalloproteinase 9-mediated degradation of type II collagen (C2M) were analyzed herein. Serum samples from a cross-sectional knee osteoarthritis cohort, as well as pediatric and rheumatoid arthritis samples, were assayed for PIIBNP and PIIANP. Western blot showed that the antibody recognized PIIBNP either as a free fragment or attached to the main molecule. Immunohistochemistry demonstrated that PIIBNP was predominately located in the extracellular matrix of the superficial and deep zones and chondrocytes in both normal and osteoarthritic articular cartilage. In addition, the hsPRO-C2 immunoassay exhibits acceptable technical performances. In the human cartilage explants model, levels of PIIBNP, but not PIIANP and C2M, were increased (2 to 7-fold) time-dependently in response to IGF-1. Moreover, there was no significant correlation between PIIBNP and PIIANP levels when measured in knee osteoarthritis, rheumatoid arthritis, and pediatric serum samples. Serum PIIBNP was significantly higher in controls (KL0/1) compared to OA groups (KL2/3/4, p = 0.012). The hsPRO-C2 assay shows completely different biological and clinical patterns than PIIANP ELISA, suggesting that it may be a promising biomarker of cartilage formation.

Sprifermin (rhFGF18) modulates extracellular matrix turnover in cartilage explants ex vivo

Background

Sprifermin (recombinant human fibroblast growth factor 18) is in clinical development as a potential disease-modifying osteoarthritis drug (DMOAD). In vitro studies have shown that cartilage regenerative properties of sprifermin involve chondrocyte proliferation and extracellular matrix (ECM) production. To gain further insight into the process of sprifermin in the cartilage tissue, this study aimed at investigating the ECM turnover of articular cartilage explants in a longitudinal manner.

Methods

Bovine full-depth articular cartilage explants were stimulated with sprifermin or placebo at weekly intervals, similar to the dosing regimen used in clinical trials. Pre-culturing with oncostatin M and tumour necrosis factor-α, was also used to induce an inflammatory state before treatment. Metabolic activity was measured using AlamarBlue, and chondrocyte proliferation was visualized by immuno-histochemical detection of proliferating cell nuclear antigen. ECM turnover was quantified by biomarker ELISAs; ProC2 reflecting type II collagen formation, CS846 reflecting aggrecan formation, active MMP9, C2M and AGNx2 reflecting matrix metalloproteinase activity, and AGNx1 reflecting aggrecanase activity.

Results

Sprifermin was able to reach the chondrocytes through the extracellular matrix, as it increased cell proliferation and metabolic activity of explants. ProC2 and CS846 was dose-dependently increased (P < 0.05) by sprifermin compared to placebo, while C2M and AGNx2 were unaffected, active MMP9 was slightly decreased, and AGNx1 was slightly increased. Over the course of treatment, the temporal order of ECM turnover responses was AGNx1, then ProC2, followed by CS846 and MMP9. Pro-inflammatory activation of the explants diminished the ECM turnover responses otherwise observed under non-inflammatory conditions.

Conclusions

The data suggest that sprifermin has chondrogenic effects on articular cartilage ex vivo, exerted through a sequential process of ECM turnover; aggrecan degradation seems to occur first, while type II collagen and aggrecan production increased at a later time point. In addition, it was observed that these chondrogenic effects are dependent on the inflammatory status of the cartilage prior to treatment.

Electronic supplementary material

The online version of this article (10.1186/s12967-017-1356-8) contains supplementary material, which is available to authorized users.

Predictive and concurrent validity of cartilage thickness change as a marker of knee osteoarthritis progression: data from the Osteoarthritis Initiative

OBJECTIVE

To investigate the predictive and concurrent validity of magnetic resonance imaging (MRI)-based cartilage thickness change between baseline (BL) and year-two (Y2) follow-up (predictive validity) and between Y2 and Y4 follow-up (concurrent validity) for symptomatic and radiographic knee osteoarthritis (OA) progression during Y2→Y4.

METHODS

777 knees from 777 Osteoarthritis Initiative (OAI) participants (age: 61.3 ± 9.0 years, BMI: 30.1 ± 4.8 kg/m²) with Kellgren Lawrence (KL) grade 1-3 at Y2 (visit before progression interval) had cartilage thickness measurements from 3T MRI at BL, Y2 (n = 777), and Y4 (n = 708). Analysis of covariance and logistic regression were used to assess the association of pain progression (≥9 WOMAC units [scale 0-100], n = 205/572 with/without progression) and radiographic progression (≥0.7 mm minimum joint space width (mJSW) loss, n = 166/611 with/without progression) between Y2 and Y4 with preceding (BL→Y2) and concurrent (Y2→Y4) change in central medial femorotibial (cMFTC) compartment cartilage thickness.

RESULTS

Symptomatic progression was associated with concurrent (Y2→Y4: -305 ± 470 μm vs -155 ± 346 μm, Odds ratios (OR) = 1.5 [1.2, 1.7]) but not with preceding cartilage thickness loss in cMFTC (-150 ± 276 μm vs -151 ± 299 μm, OR = 0.9 95% CI: [0.8, 1.1]). Radiographic progression, in contrast, was significantly associated with both concurrent (-542 ± 550 μm vs -98 ± 255 μm, OR = 3.4 [2.6, 4.3]) and preceding cMFTC thickness loss (-229 ± 355 μm vs -130 ± 270 μm, OR = 1.3 [1.1, 1.5]).

CONCLUSIONS

These results extend previous reports that did not discern predictive vs concurrent associations of cartilage thickness loss with OA progression. The observed predictive and concurrent validity of cartilage thickness loss for radiographic progression and observed concurrent validity for symptomatic progression provide an important step in qualifying cartilage thickness loss as a biomarker of knee OA progression. CLINICALTRIALS.

GOV IDENTIFICATION

NCT00080171.

Sprifermin (rhFGF18) enables proliferation of chondrocytes producing a hyaline cartilage matrix

OBJECTIVE

Fibroblast growth factor (FGF) 18 has been shown to increase cartilage volume when injected intra-articularly in animal models of osteoarthritis (OA) and in patients with knee OA (during clinical development of the recombinant human FGF18, sprifermin). However, the exact nature of this effect is still unknown. In this study, we aimed to investigate the effects of sprifermin at the cellular level.

DESIGN

A combination of different chondrocyte culture systems was used and the effects of sprifermin on proliferation, the phenotype and matrix production were evaluated. The involvement of MAPKs in sprifermin signalling was also studied.

RESULTS

In monolayer, we observed that sprifermin promoted a round cell morphology and stimulated both cellular proliferation and Sox9 expression while strongly decreasing type I collagen expression. In 3D culture, sprifermin increased the number of matrix-producing chondrocytes, improved the type II:I collagen ratio and enabled human OA chondrocytes to produce a hyaline extracellular matrix (ECM). Furthermore, we found that sprifermin displayed a 'hit and run' mode of action, with intermittent exposure required for the compound to fully exert its anabolic effect. Finally, sprifermin appeared to signal through activation of ERK.

CONCLUSIONS

Our results indicate that intermittent exposure to sprifermin leads to expansion of hyaline cartilage-producing chondrocytes. These in vitro findings are consistent with the increased cartilage volume observed in the knees of OA patients after intra-articular injection with sprifermin in clinical studies.

Association Between Biochemical Markers of Bone Turnover and Bone Changes on Imaging: Data From the Osteoarthritis Initiative

OBJECTIVE

To determine the relationship between biochemical markers involved in bone turnover and bone features on imaging in knees with osteoarthritis (OA).

METHODS

We analyzed data from the Foundation for the National Institutes of Health OA Biomarkers Consortium within the Osteoarthritis Initiative (n = 600). Bone marrow lesions (BMLs), osteophytes, and subchondral bone area (mm² ) and shape (position on 3-D vector) were assessed on magnetic resonance images, and bone trabecular integrity (BTI) was assessed on radiographs. Serum and urinary markers (serum C-terminal crosslinked telopeptide of type I collagen [CTX-I], serum crosslinked N-telopeptide of type I collagen [NTX-I], urinary NTX-I, urinary C-terminal crosslinked telopeptide of type II collagen [CTX-II], and urinary CTX-Iα and CTX-Iβ) were measured. The associations between biochemical and imaging markers at baseline and over 24 months were assessed using regression models adjusted for covariates.

RESULTS

At baseline, most biochemical markers were associated with BMLs, with C statistics for the presence/absence of any BML ranging from 0.675 to 0.688. At baseline, urinary CTX-II was the marker most consistently associated with BMLs (with odds of having ≥5 subregions affected compared to no BML increasing by 1.92-fold [95% confidence interval (95% CI) 1.25, 2.96] per 1 SD of urinary CTX-II), large osteophytes (odds ratio 1.39 [95% CI 1.10, 1.77]), bone area and shape (highest partial R²  = 0.032), and changes in bone shape over 24 months (partial R² range 0.008 to 0.024). Overall, biochemical markers were not predictive of changes in BMLs or osteophytes. Serum NTX-I was inversely associated with BTI of the vertical trabeculae (quadratic slope) in all analyses (highest partial R²  = 0.028).

CONCLUSION

We found multiple significant associations, albeit mostly weak ones. The role of systemic biochemical markers as predictors of individual bone anatomic features of single knees is limited based on our findings.

Disease-modifying treatments for osteoarthritis (DMOADs) of the knee and hip: lessons learned from failures and opportunities for the future

Osteoarthritis (OA) is the biggest unmet medical need among the many musculoskeletal conditions and the most common form of arthritis. It is a major cause of disability and impaired quality of life in the elderly. We review several ambitious but failed attempts to develop joint structure-modifying treatments for OA. Insights gleaned from these attempts suggest that these failures arose from unrealistic hypotheses, sub-optimal selection of patient populations or drug dose, and/or inadequate sensitivity of the trial endpoints. The long list of failures has prompted a paradigm shift in OA drug development with redirection of attention to: (1) consideration of the benefits of localized vs systemic pharmacological agents, as indicated by the increasing number of intra-articularly administered compounds entering clinical development; (2) recognition of OA as a complex disease with multiple phenotypes, that may each require somewhat different approaches for optimizing treatment; and (3) trial enhancements based on guidance regarding biomarkers provided by regulatory agencies, such as the Food and Drug Administration (FDA), that could be harnessed to help turn failures into successes.

Synovitis biomarkers: ex vivo characterization of three biomarkers for identification of inflammatory osteoarthritis

Objective: Characterize biomarkers measuring extracellular matrix turnover of inflamed osteoarthritis synovium.

Methods: Human primary fibroblast-like synoviocytes and synovial membrane explants (SMEs) treated with various cytokines and growth factors were assessed by C1M, C3M, and acMMP3 in the conditioned medium.

Results: TNFα significantly increased C1M up to seven-fold (p = 0.0002), C3M up to 24-fold (p = 0.0011), and acMMP3 up to 14-fold (p < 0.0001) in SMEs. IL-1β also significantly increased C1M up to five-fold (p = 0.00094), C3M four-fold (p = 0.007), and acMMP3 18-fold (p < 0.0001) in SMEs.

Conclusion: The biomarkers C1M, C3M, and acMMP-3 were synovitis biomarkers ex vivo and provide a translational tool together with the SME model.

Osteoarthritis year in review 2015: soluble biomarkers and the BIPED criteria

OBJECTIVE

To review and summarize biomarker data published from April 2014 to May 2015 to provide insight to the ongoing work in the field of osteoarthritis (OA). Furthermore, to summarize the BIPED criteria and set it in context of the medical needs of 2015.

METHODS

PubMed was used as searching machine: Time period 2014/04/01-2015/05/01, MeSH term [Biomarker] AND [Osteoarthritis], Language; English, Full text available. Reviews were excluded. Only papers describing protein based biomarkers measured in human body fluids from OA patients were included.

RESULTS

Biomarkers of joint tissue turnover, cytokines, chemokines and peptide arrays were measured in different cohorts and studies. Amongst those were previously tested biomarkers such as osteocalcin, Carboxy-terminal cross-linked fragment of type II collagen (CTX-II) and cartilage oligomeric matrix protein (COMP). A majority of the biomarker were classified as I, B or B biomarkers according to the BIPED criteria. Work is continuing on testing biomarkers in OA. There is still a huge, unmet medical need to identify, test, validate and qualify novel and well-known biomarkers. A pre-requisite for this is better characterization and classification of biomarkers to their needs, which may not be reached before higher understanding of OA phenotypes has been gained. In addition, we provide some references to some recent guidelines from Food and Drug Administration (FDA) and European Medicines Agency (EMA) on qualification and usage of biomarkers for drug development and personalized medicine, which may provide value to the field.

Greater Lateral Femorotibial Cartilage Loss in Osteoarthritis Initiative Participants With Incident Total Knee Arthroplasty: A Prospective Cohort Study

OBJECTIVE

To explore whether baseline to 12-month followup change in femorotibial cartilage thickness differs between subjects who received a total knee arthroplasty (TKA) between 24 and 60 months from those without TKA (non-TKA).

METHODS

In this prospective cohort study, 531 right knees from Osteoarthritis Initiative participants with definite radiographic knee osteoarthritis (Kellgren/Lawrence [K/L] grades 2-4) were studied. Segmentation was applied to coronal fast low-angle shot magnetic resonance images, to quantitatively determine cartilage thickness in 16 femorotibial subregions. Unadjusted P values (t-tests) and P values adjusted for age, baseline body mass index (BMI), K/L grade, and sex (generalized estimating equation models) were used to evaluate differences in longitudinal 1-year rates of cartilage thickness between TKAs and non-TKAs, with total knee arthroplasty status as fixed effect.

RESULTS

Of the 531 participants (mean ± SD ages 63 ± 9 years, BMI 30 ± 4.8 kg/m(2)), 40 received a femorotibial TKA within 4 years. At baseline, TKAs had thinner medial and lateral femorotibial cartilage (-15%; P < 0.001) than non-TKAs. Longitudinal cartilage thickness change was significantly greater in TKAs than in non-TKAs in the total femorotibial joint (area under the curve [AUC] 0.64), the lateral compartment (AUC 0.66), both tibiae (AUC ≥ 0.61), and the first 9 (of 16) ordered values of subregion change (AUC 0.64-0.69). Discrimination was stronger for TKAs that occurred at 24 and 36 months (n = 18) than for those at 48 and 60 months (n = 22).

CONCLUSION

Knees with incident TKA displayed smaller baseline cartilage thickness and greater lateral as well as location-independent ordered value femorotibial cartilage loss than non-TKAs. Discrimination of cartilage loss was greater for TKAs occurring within 2 years after the measurement than for those occurring later.

OA phenotypes, rather than disease stage, drive structural progression--identification of structural progressors from 2 phase III randomized clinical studies with symptomatic knee OA

BACKGROUND/PURPOSE

The aim of this study was to identify key characteristics of disease progression through investigation of the association of radiographic progression over two years with baseline Joint Space Width (JSW), Kellgren-Lawrence (KL) grade, Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain, Joint Space Narrowing (JSN), and BMI.

METHODS

Data from 2206 subjects (4390 knees) were combined for this post-hoc analysis of two randomized, double-blind, multi-center, placebo-controlled phase III trials (NCT00486434 and NCT00704847) that evaluated the efficacy and safety of 2-years treatment with oral salmon calcitonin of subjects with painful knee osteoarthritis (OA).

RESULTS

There was a clear positive and significant correlation between KL grade and WOMAC pain and total WOMAC, albeit the variance in pain measures was from min-to-max for all KL categories, emphasizing the heterogeneity of this patient population and pain perception. 32% of target knees did not progress, and only 51% had changes over minimum significant change (MSC). BMI, KL-Score and WOMAC pain was diagnostic, but only KL-score and pain had prognostic value, albeit pain in a non-linear manner.

CONCLUSION

These data clearly describe significant associations between KL grade, JSW, pain and BMI in patients with symptomatic knee OA. KL grade, BMI and WOMAC pain were diagnostically associated with OA based on JSW but only KL-score and pain in a non-linier fashion was prognostic. 50% of patients did not progress more than MSC, highlighting the importance for identification of structural progressors and the phenotypes associated with these. These results suggest that disease phenotypes, rather than disease status, are responsible for disease progression.

Rates and sensitivity of knee cartilage thickness loss in specific central reading radiographic strata from the osteoarthritis initiative

OBJECTIVE

To compare the rate and sensitivity to change of quantitative cartilage thickness change with magnetic resonance imaging (MRI) across specific radiographic strata of knee osteoarthritis (KOA) from central expert readings of the Osteoarthritis Initiative (OAI). Specifically, we explored whether Kellgren Lawrence grade (KLG) 2 knees with radiographic joint space narrowing (JSN) displayed greater cartilage loss than those without JSN, and whether knees with medial JSN grade2 had greater loss than those with grade1.

METHODS

One-year femorotibial cartilage thickness change was obtained for 836 knees, 112 without, and 724 with definite radiographic KOA based on baseline site readings. The maximum subregional cartilage loss, and cartilage thickness change in the total femorotibial joint (FTJ) and medial femorotibial compartment (MFTC) were analyzed across different radiographic strata (central vs site readings).

RESULTS

The maximum subregional rate of change was significantly greater in central_KLG2 knees with than in those without JSN (172 ± 152 vs 134 ± 100 μm; P = 0.03). In contrast, the rate did not differ significantly between central_KLG1 knees with and without JSN. MFTC cartilage loss in central_medial_grade2 JSN knees was substantially and significantly greater than in grade1 knees (-70 ± 159 vs -31 ± 126 μm; P = 0.02). For comparison, the loss in grade3 knees was -72 ± 122 μm.

CONCLUSIONS

In KLG2 knees, presence of radiographic JSN was associated with significantly and substantially greater rates of subregional cartilage loss. Differentiating knees with mild vs moderate medial JSN, and definite radiographic OA knees with vs without JSN is important in predicting structural progression of KOA, and for planning clinical trials testing the efficacy of disease modifying drugs (DMOADs).

Trajectory of cartilage loss within 4 years of knee replacement--a nested case-control study from the osteoarthritis initiative

OBJECTIVE

Knee replacement (KR) represents a clinically important endpoint of knee osteoarthritis (KOA). Here we examine the 4-year trajectory of femoro-tibial cartilage thickness loss prior to KR vs non-replaced controls.

METHODS

A nested case-control study was performed in Osteoarthritis Initiative (OAI) participants: Cases with KR between 12 and 60 month (M) follow-up were each matched with one control (without KR through 60M) by age, sex, and baseline radiographic stage. Femoro-tibial cartilage thickness was measured quantitatively using magnetic resonance imaging (MRI) at the annual visit prior to KR occurrence (T0), and at 1-4 years prior to T0 (T-1 to T-4). Cartilage loss between cases and controls was compared using paired t-tests and conditional logistic regression.

RESULTS

One hundred and eighty-nine knees of 164 OAI participants [55% women; age 64 ± 8.7; body mass index (BMI) 29 ± 4.5] had KR and longitudinal cartilage data. Comparison of annualized slopes of change across all time points revealed greater loss in the central medial tibia (primary outcome) in KRs than in controls [94 ± 137 vs 55 ± 104 μm; P = 0.0017 (paired t); odds ratio (OR) 1.36 (95% confidence interval (CI): 1.08-1.70)]. The discrimination was stronger for T-2 → T0 [OR 1.61 (1.33-1.95), n = 127] than for T-1 → T0, and was not statistically significant for intervals prior to T-2 [i.e., T-4 → T-2, OR 0.97 (0.67-1.41), n = 60]. Results were similar for total medial femoro-tibial cartilage loss (secondary outcome), and when adjusting for pain and BMI.

CONCLUSIONS

In knees with subsequent replacement, cartilage loss accelerates in the 2 years, and particularly in the year prior to surgery, compared with controls. Whether slowing this cartilage loss can delay KR remains to be determined.

Characterization of Novel PI3Kδ Inhibitors as Potential Therapeutics for SLE and Lupus Nephritis in Pre-Clinical Studies

SLE is a complex autoimmune inflammatory disease characterized by pathogenic autoantibody production as a consequence of uncontrolled T–B cell activity and immune-complex deposition in various organs, including kidney, leading to tissue damage and function loss. There is a high unmet need for better treatment options other than corticosteroids and immunosuppressants. Phosphoinositol-3 kinase δ (PI3Kδ) is a promising target in this respect as it is essential in mediating B- and T-cell function in mouse and human. We report the identification of selective PI3Kδ inhibitors that blocked B-, T-, and plasmacytoid dendritic cell activities in human peripheral blood and in primary cell co-cultures (BioMAP^®) without detecting signs of undesired toxicity. In an IFNα-accelerated mouse SLE model, our PI3Kδ inhibitors blocked nephritis development, whether administered at the onset of autoantibody appearance or the onset of proteinuria. Disease amelioration correlated with normalized immune cell numbers in the spleen, reduced immune-complex deposition as well as reduced inflammation, fibrosis, and tissue damage in the kidney. Improvements were similar to those achieved with a frequently prescribed drug for lupus nephritis, the potent immunosuppressant mycophenolate mofetil. Finally, we established a pharmacodynamics/pharmacokinetic/efficacy model that revealed that a sustained PI3Kδ inhibition of 50% is sufficient to achieve full efficacy in our disease model. These data demonstrate the therapeutic potential of PI3Kδ inhibitors in SLE and lupus nephritis.

Osteoarthritis--a case for personalized health care?

For both economic and ethical reasons, identification of the optimal treatment for each individual patient is a pressing concern, not only for the patients and their physician, but also health care payers and the pharmaceutical industry. In the field of osteoarthritis (OA) this is of particular relevance, due to the heterogeneity of the disease and the very large number of affected individuals. There is a need to pair the right patients with the right therapeutic modes of action. At present, the clinical trial failures in OA may be a consequence of both bona fide treatment failures and trial failures due to clinical design deficiencies. Tools are needed for characterization and segregation of patients with OA. Key lessons may be learned from advances with another form of arthritis, namely rheumatoid arthritis (RA). Personalized health care (PHC) may be more advantageous for a number of specific indications which are characterized by costly therapy, low response rates and significant problems associated with trial and error prescription, including the risk of serious side effects. We discuss the use of diagnostic practices guiding RA treatment, which may serve as a source of key insights for diagnostic practices in OA. We discuss the emerging concept of PHC, and outline the opportunities and current successes and failures across the RA field, as the OA field collects further data to support the hypothesis. We attempt to outline a possible path forward to assist patients, physicians, payers and the pharmaceutical industry in assuring the 'right' patients are treated with the 'right drug' in OA. Finally we highlight methods for possible segregation of OA patients that would allow identification of patient subtypes, such as OA driven by inflammation that may be ideally suited for PHC and for targeted therapies.

Pharmacologic P2X purinergic receptor antagonism in the treatment of collagen-induced arthritis

OBJECTIVE

To assess the therapeutic potential of a P2X purinergic receptor antagonist, namely, periodate oxidized ATP, in collagen-induced arthritis (CIA).

METHODS

Arthritis was induced in male DBA/1J mice by immunization with type II collagen (CII). Animals showing digit inflammation and paw swelling were treated intraperitoneally with 100 μl of 3 mM oxidized ATP daily for 10 days. At the end of the treatment period, animals were killed and paws were removed for histologic analysis and evaluation of T cell infiltration. Humoral response to CII was analyzed, and specific serum autoantibody levels were correlated with the clinical scores observed in the different treatment groups.

RESULTS

Treatment with oxidized ATP resulted in a sustained reduction in disease activity, which was associated with a significant decrease in CD3+ T cell infiltration in arthritic lesions and a significant amelioration of cartilage erosion. Peripheral Treg cells were significantly increased upon P2X blockade in mouse lymph nodes. Moreover, a marked reduction in circulating autoantibodies directed against mouse CII was detected. There was a significant correlation between serum autoantibody levels and the clinical efficacy of oxidized ATP.

CONCLUSION

Our findings indicate that P2X receptor antagonism has important therapeutic potential in chronic inflammatory rheumatic disorders. Taken together, our results underscore the value of the P2X receptor signaling pathway as a potential pharmacologic target for the modulation of adaptive immunity in CIA.

FGF18 augments osseointegration of intra-medullary implants in osteopenic FGFR3(-/-) mice

Enhancement of endogenous bone regeneration is a priority for integration of joint replacement hardware with host bone for stable fixation of the prosthesis. Fibroblast Growth Factor (FGF) 18 regulates skeletal development and could therefore have applications for bone regeneration and skeletal repair. This study was designed to determine if treatment with FGF 18 would promote bone regeneration and integration of orthopedic hardware in FGF receptor 3 deficient (FGFR3(-/-)) mice, previously characterized with impaired bone formation. Rigid nylon rods coated with 200 nm of titanium were implanted bilaterally in the femora of adult FGFR3(-/-) and FGFR3(+/+) mice to mimic human orthopedic hardware. At the time of surgery, LEFT femora received an intramedullary injection of 0.5 μg FGF18 (Merck Serono) and RIGHT femora received PBS as a control. Treatment with FGF18 resulted in a significant increase in peri-implant bone formation in both FGFR3(+/+) and FGFR3(-/-) mice, with the peri-implant fibrous tissue frequently seen in FGFR3(-/-) mice being largely replaced by bone. The results of this pre-clinical study support the conjecture that FGF18 could be used in the clinical setting to promote integration of orthopedic hardware in poor quality bone.

Dysregulation of bacterial proteolytic machinery by a new class of antibiotics

Here we show that a new class of antibiotics-acyldepsipeptides-has antibacterial activity against Gram-positive bacteria in vitro and in several rodent models of bacterial infection. The acyldepsipeptides are active against isolates that are resistant to antibiotics in clinical application, implying a new target, which we identify as ClpP, the core unit of a major bacterial protease complex. ClpP is usually tightly regulated and strictly requires a member of the family of Clp-ATPases and often further accessory proteins for proteolytic activation. Binding of acyldepsipeptides to ClpP eliminates these safeguards. The acyldepsipeptide-activated ClpP core is capable of proteolytic degradation in the absence of the regulatory Clp-ATPases. Such uncontrolled proteolysis leads to inhibition of bacterial cell division and eventually cell death.

Biological characterization of novel inhibitors of the gram-positive DNA polymerase IIIC enzyme

Novel N-3-alkylated 6-anilinouracils have been identified as potent and selective inhibitors of bacterial DNA polymerase IIIC, the enzyme essential for the replication of chromosomal DNA in gram-positive bacteria. A nonradioactive assay measuring the enzymatic activity of the DNA polymerase IIIC in gram-positive bacteria has been assembled. The 6-anilinouracils described inhibited the polymerase IIIC enzyme at concentrations in the nanomolar range in this assay and displayed good in vitro activity (according to their MICs) against staphylococci, streptococci, and enterococci. The MICs of the most potent derivatives were about 4 microg/ml for this panel of bacteria. The 50% effective dose of the best compound (6-[(3-ethyl-4-methylphenyl)amino]-3-{[1-(isoxazol-5-ylcarbonyl)piperidin-4-yl]methyl}uracil) was 10 mg/kg of body weight after intravenous application in a staphylococcal sepsis model in mice, from which in vivo pharmacokinetic data were also acquired.

Protection against murine tuberculosis by an attenuated recombinant Salmonella typhimurium vaccine strain that secretes the 30-kDa antigen of Mycobacterium bovis BCG

A recombinant (r-) Salmonella typhimurium aroA vaccine that secretes the naturally secreted protein of Mycobacterium bovis strain BCG, Ag85B, by means of the HlyB/HlyD/TolC export machinery (termed p30 in the following) was constructed. In contrast to r-S. typhimurium control, oral vaccination of mice with the r-S. typhimurium p30 construct induced partial protection against an intravenous challenge with the intracellular pathogen Mycobacterium tuberculosis, resulting in similar vaccine efficacy comparable to that of the systemically administered attenuated M. bovis BCG strain. The immune response induced by r-S. typhimurium p30 was accompanied by augmented interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) levels produced by restimulated splenocytes. These data suggest that the HlyB/HlyD/TolC-based antigen delivery system with attenuated r-S. typhimurium as carrier is capable of inducing an immune response against mycobacterial antigens.

Protein p60 participates in intestinal host invasion by Listeria monocytogenes

The role of p60 in intestinal invasion by Listeria monocytogenes was assessed after oral infection of mice with the p60 low-expressing mutant RIII, or with anti-p60 antibody coated wild-type EGD. Invasion by L. monocytogenes RIII bacteria has been unimpaired suggesting that a low density of p60 suffices for entry. Up to 24 h post infection (p.i.), intestinal penetration by L. monocytogenes EGD bacteria was markedly reduced by coating with anti-p60 antibodies. In histological sections, anti-p60 antibody-treated L. monocytogenes EGD, but not uncoated listeriae were still detectable 24 h p.i. at the apical surface of enterocytes in the intestine. We conclude that p60 contributes to host invasion through the natural port of listerial entry, the intestinal epithelium.

Salmonella typhimurium aroA- infection in gene-targeted immunodeficient mice: major role of CD4+ TCR-alpha beta cells and IFN-gamma in bacterial clearance independent of intracellular location

Due to the dependency on aromatic precursors, the growth of Salmonella typhimurium aroA- is limited in immunocompetent mice. Here we show that H-21-A beta-/- mice (lacking MHC class II molecules and thus devoid of mature CD4+ TCR-alpha beta cells), TCR-beta-/- mice (devoid of TCR-alpha beta cells), and IFN-gamma R-/- mice (unresponsive to IFN-gamma) are highly susceptible to S. typhimurium aroA- infection compared with heterozygous controls. In contrast, beta 2m-deficient mice (lacking surface MHC class I and thus devoid of conventional CD8+ T cells) or TCR-delta-/- mice (devoid of TCR-gamma delta cells) were equally as resistant to S. typhimurium aroA- infection as their heterozygous littermates. These findings emphasize the vital role of CD4+ TCR-alpha beta cells and IFN-gamma in resistance against S. typhimurium aroA-. Sublethal inocula of S. typhimurium aroA- led to permanent infection in H-21-A beta-/- mice, suggesting that bacterial starvation is insufficient for sterile clearance in immunocompetent mice and that MHC class II-dependent immune mechanisms are required for pathogen eradication. The TCR-beta-/- mice suffered from salmonellosis more severely than the MHC class II-deficient mutants, suggesting an auxiliary function of CD8+ T cells. Recombinant S. typhimurium aroA-, secreting listeriolysin (Hly) of Listeria monocytogenes, are capable of escaping from the phagosome into the cytosol of the host cell. However, the course of infection of these recombinant S. typhimurium SL7207 Hlys and control strains did not differ in beta 2m-/- mutants. This finding argues against direct correlation of cytosolic location of S. typhimurium SL7207 Hlys with CD8+ T cell dependency of protection.

Salmonella typhimurium aroA- infection in gene-targeted immunodeficient mice: major role of CD4+ TCR-alpha beta cells and IFN-gamma in bacterial clearance independent of intracellular location

Due to the dependency on aromatic precursors, the growth of Salmonella typhimurium aroA- is limited in immunocompetent mice. Here we show that H-21-A beta-/- mice (lacking MHC class II molecules and thus devoid of mature CD4+ TCR-alpha beta cells), TCR-beta-/- mice (devoid of TCR-alpha beta cells), and IFN-gamma R-/- mice (unresponsive to IFN-gamma) are highly susceptible to S. typhimurium aroA- infection compared with heterozygous controls. In contrast, beta 2m-deficient mice (lacking surface MHC class I and thus devoid of conventional CD8+ T cells) or TCR-delta-/- mice (devoid of TCR-gamma delta cells) were equally as resistant to S. typhimurium aroA- infection as their heterozygous littermates. These findings emphasize the vital role of CD4+ TCR-alpha beta cells and IFN-gamma in resistance against S. typhimurium aroA-. Sublethal inocula of S. typhimurium aroA- led to permanent infection in H-21-A beta-/- mice, suggesting that bacterial starvation is insufficient for sterile clearance in immunocompetent mice and that MHC class II-dependent immune mechanisms are required for pathogen eradication. The TCR-beta-/- mice suffered from salmonellosis more severely than the MHC class II-deficient mutants, suggesting an auxiliary function of CD8+ T cells. Recombinant S. typhimurium aroA-, secreting listeriolysin (Hly) of Listeria monocytogenes, are capable of escaping from the phagosome into the cytosol of the host cell. However, the course of infection of these recombinant S. typhimurium SL7207 Hlys and control strains did not differ in beta 2m-/- mutants. This finding argues against direct correlation of cytosolic location of S. typhimurium SL7207 Hlys with CD8+ T cell dependency of protection.

Superior efficacy of secreted over somatic antigen display in recombinant Salmonella vaccine induced protection against listeriosis

Vaccination provides the most potent measure against infectious disease, and recombinant (r) viable vaccines expressing defined pathogen-derived antigens represent powerful candidates for future vaccination strategies. In a new approach we constructed r-aroA- Salmonella typhimurium displaying p60 or listeriolysin (Hly) antigen of Listeria monocytogenes in secreted or somatic form in the host cell. Vaccination of mice with r-aroA- S. typhimurium induced protection against the intracellular pathogen L. monocytogenes only with secreted and not with somatic antigen. Secreted Hly was slightly more potent in inducing protective immunity than secreted p60. Both r-aroA- S. typhimurium secreting p60 in the endosome and r-aroA- S. typhimurium secreting Hly in the cytosol induced protective CD4+ and CD8+ T-cells suggesting CD8+ T-cell stimulation independent from intracellular residence of r-aroA- S. typhimurium carriers. Hence, not only the type of antigen but also its display by the r-carrier within the host cell critically influences vaccine efficacy.