- Email: [email protected]
Getting evidence into practice: pragmatic trials and implementation research
Abstracts / Osteoarthritis and Cartilage 24 (2016) S1eS7
protein expression or miR-140 expression. The AcanKO and miR-140KO clones showed no change in cell growth. The AcanKO clones maintained the cartilage phenotype as demonstrated expression of chondrocyte marker genes, including, Col2a1, Col1a2, Matn1 and Comp. When injected subcutaneously in nude mice the RCS or RCS/Cas9 cell lines generated a chondrosarcoma with a fully cartilaginous matrix. In contrast the AcanKO cell line generated a much smaller tumor-like tissue with few chondrocyte-like cells and substantial infiltration of immune cells. The loss of miR-140 expression was consistent with the indel size and presence in the seed sequence. Expression of cartilage genes, Col2a1, Comp and Acan were reduced in the miR-140KO cells but this did not appear to be associated with loss of phenotype. Expression of the miR-140 host gene WWP2 was unaffected by the targeted mutations indicating that changes in cell function observed were not associated with changes in expression of the host gene. The mutations were shown to affect miRNA maturation. Gene array analysis surprisingly showed no change in those genes, Adamts5, Pdgfa, Dnpep, Sp1, Hdac4 and Igfpb1, previously suggested to be miR-140 targets. Conclusion: The cell line described and similar chondrocyte cell lines under development will enable utilization of the extensive and rapidly expanding scope of the CRISP/Cas9 system to characterize gene function in chondrocytes. Some of the capacities of the CRISPR/Cas9 system that include; the use of arrayed sgRNA libraries for the identification of genes essential for survival, proliferation or other specific chondrocyte functions such as suppression of terminal differentiation; and the identification of epigenomic mechanisms, including histone modification, for gene regulation will be discussed. I-11 NOVEL APPROACHES TO DELIVERY OF IA THERAPY IN OA A.J. Grodzinsky. MIT, Cambridge, MA, USA Purpose: Osteoarthritis affects individual joints making intraarticular (i.a.) therapy a desirable treatment option, yet simple i.a. injection remains inadequate because drugs are rapidly cleared from the joint space via the lymphatics or vasculature. We will focus on the range of current approaches involving the use of micro-and nano-particle drug carriers intended for sustained release of drugs in the joint, as well as novel methods by which drug carriers can be delivered directly inside cartilage. Methods for intra-cartilage delivery incorporating mechanisms for binding of drug carriers inside cartilage enables targeting of hondrocytes and ECM, and additionally enables cartilage to act as a depot for delivery to other adjacent joint tissues. I-12 MICRORNAS: THE ROLE OF MICRORNAS IN THE PATHOGENESIS, DETECTION AND TREATMENT OF OA I. Clark y, T.E. Swingler y, L.T. Le y, N. Crowe y, M.J. Barter z, G. Wheeler y, T. Dalmay y, D.A. Young z. y Univ. of East Anglia, Norwich, United Kingdom; z Newcastle Univ., Newcastle-upon-Tyne, United Kingdom This session will review the role of microRNAs in the molecular pathogenesis of osteoarthritis (OA). It will present data on the regulation of microRNAs by relevant factors and their impact on intracellular signalling. Key targets of microRNAs in OA will also be explored. MicroRNAs have also been reported as circulating biomarkers of disease, and the utility of this approach and how it informs on the functional role of microRNAs will be discussed. Finally, the potential for microRNAs to be used therapeutically and the hurdles which need to be overcome to do this will be addressed. The focus of the Clark lab has been on the role and function of microRNAs in cartilage, particularly miR-455, the miR-29 family, miR-140 and miR-3085. MicroRNA-455 is genomically located within an intron of COL27A1. Collagen XXVII is expressed in cartilage, suggesting function of the miR in this tissue. We initially described a role for miR-455 in TGFbeta signalling, but have more recently uncovered function in Wnt signalling and in the regulation of Sirt1. The miR-29 family have been well-researched and are known e.g. to regulate collagen gene expression, giving them a role in fibroses. We identified miR-29b as one of only two miRs which was regulated at an early time point after surgery in the murine DMM (‘destabilisation of the medial meniscus’) model of OA. Potential targets of miR-29 were regulated in the opposite direction to the miR, suggesting function. The
S3
miR-29 family were regulated in many models of chondrocyte differentiation and in human end-stage OA. In chondrocytes we have shown that miR-29 is negatively regulated by Sox9 and negatively regulates a number of key intracellular signalling pathways in OA. We have identified novel direct targets in the Wnt pathway and we have also shown that miR-29 directly targets a number of ADAMTS protease genes. We used RNA-Seq to explore the full range of miRs expressed by human articular chondrocytes from OA patients. This showed that the so-called passenger strand of miR-140, miR-140-3p was more highly expressed than the guide strand, miR-140-5p in newly isolated osteoarthritic chondrocytes. We have now shown that miR-140-3p directly targets a number of enzymes in the heparan sulphate proteoglycan synthesis pathway. These studies also identified miR-3085 in human chondrocytes. This miR had only previously been annotated in rodents where it was presumed intergenic. However, in man it is located in the final intron of the CRTAC1 gene, which codes for cartilage acidic protein 1. We have shown it to directly target ITGA5, the integrin alpha5 gene, but it also strongly induces interleukin-1 signalling in chondrocytes. I-13 GETTING EVIDENCE INTO PRACTICE: PRAGMATIC TRIALS AND IMPLEMENTATION RESEARCH K. Dziedzic. Keele Univ., Keele, United Kingdom The randomized controlled trial (RCT) is a versatile design that has evolved from studies of efficacy and proof of principle to pragmatic trials of clinical effectiveness and complex interventions. The RCT has formed the basis of evidence based practice and international treatment guidelines. Increasingly the design has been applied to studies of implementation where new models of care have been compared with usual care in whole system implementation e.g. MOSAICS (managing osteoarthritis in consultations) a cluster randomised controlled trial in primary care (1e7). In this context the implementation study seeks to promote the intervention as an alternative to usual care with engagement of key stakeholders (organisations, health care professionals, patients), and measures uptake of the new approach with assessment of its likely sustainability beyond the study. In addition to the usual challenges of cluster designs, the MOSAICS study will be used to highlight the following considerations: Use of theoretical frameworks to plan, understand and evaluate implementation The value of mixed methods Patient and public involvement in implementation research Selection of eligible trial participants Barriers and facilitators to implementation in primary care Fidelity to protocols in the context of wide variations in usual practice Ongoing engagement of control practices Determining outcomes of quality care Reporting findings References 1. Morden A, Ong BN, Brooks L, Jinks C, Porcheret M, Edwards JJ, Dziedzic KS. Introducing Evidence Through Research “Push”: Using Theory and Qualitative Methods. Qual Health Res. 2015 Nov;25(11):1560e75. 2. Morden A, Jinks C, Ong BN, Porcheret M, Dziedzic KS. Acceptability of a 'guidebook' for the management of Osteoarthritis: a qualitative study of patient and clinician's perspectives. BMC Musculoskelet Disord. 2014 Dec 13;15:427. 3. Edwards JJ, Jordan KP, Peat G, Bedson J, Croft PR, Hay EM, Dziedzic KS. Quality of care for OA: the effect of a point-of-care consultation recording template. Rheumatology (Oxford). 2015 May;54(5):844e53. 4. Dziedzic KS, Healey EL, Porcheret M, Ong BN, Main CJ, Jordan KP, Lewis M, Edwards JJ, Jinks C, Morden A, McHugh GA, Ryan S, Finney A, Jowett S, Oppong R, Afolabi E, Pushpa-Rajah A, Handy J, Clarkson K, Mason E, Whitehurst T, Hughes RW, Croft PR, Hay EM. Implementing the NICE osteoarthritis guidelines: a mixed methods study and cluster randomised trial of a model osteoarthritis consultation in primary care– the Management of OsteoArthritis In Consultations (MOSAICS) study protocol. Implement Sci. 2014 Aug 27;9:95. 5. Porcheret M, Main C, Croft P, McKinley R, Hassell A, Dziedzic K. Development of a behaviour change intervention: a case study on the practical application of theory. Implement Sci. 2014 Apr 3;9(1):42.
S4
Abstracts / Osteoarthritis and Cartilage 24 (2016) S1eS7
6. Ong BN, Morden A, Brooks L, Porcheret M, Edwards JJ, Sanders T, Jinks C, Dziedzic K. Changing policy and practice: making sense of national guidelines for osteoarthritis. Soc Sci Med. 2014 Apr;106:101e9. 7. Edwards JJ, Khanna M, Jordan KP, Jordan JL, Bedson J, Dziedzic KS. Quality indicators for the primary care of osteoarthritis: a systematic review. Ann Rheum Dis. 2015 Mar;74(3):490e8. 2):1371e8. I-14 DYNAMIC JOINT IMAGING IN HUMAN OA: ALTERED IN VIVO CARTILAGE FUNCTION AND EARLY ONSET OA L.E. DeFrate. Duke Univ. Med. Ctr., Durham, NC, USA Mechanical loading plays a critical role in maintaining the health and function of articular cartilage. Normal cartilage loading is believed to help maintain cartilage homeostasis, while altered cartilage loading (due to factors such as obesity, joint injury, and malalignment) is believed to play a role in the degradation of cartilage. Thus, understanding the local, in vivo mechanical environment of cartilage in response to normal and pathological conditions could provide critical insights into the mechanisms contributing to osteoarthritis. However, there is limited data characterizing the local mechanical environment of cartilage in vivo. While gait analysis studies provide important information characterizing the total load transferred through the joint, it may be difficult to predict the local tissue response of cartilage from these measurements. In this regard, magnetic resonance (MR) imaging techniques provide the potential to provide additional measurements of the changes in the morphology, deformation, and composition of cartilage in vivo to gain insights into the mechanisms leading to osteoarthritis. To this end, this talk will discuss recent advances in the measurement of in vivo cartilage function using MR imaging as well as biplanar radiography. These advances are likely to provide important information that to enhance our understanding of mechanisms predisposing the joint to the development and progression of osteoarthritis. Ultimately, understanding these mechanisms is important to developing new interventions aimed at the prevention of osteoarthritis. I-15 JOINT TISSUE BIOMECHANICAL ADAPTATION)
BIOMECHANICS: JOINT RESPONSES IMPACT (THEORIES OF GROWTH
TO AND
D.R. Haudenschild. Univ. of California Davis, Sacramento, CA, USA Purpose: Joint injury often leads to osteoarthritis. The goal of our research is to disconnect OA from joint injury, and to do so we examine the events upon injury that initiate OA pathogenesis. There is the obvious damage to the joint tissues caused by the immediate mechanical insult to the joint. Joint instability also contributes, although instability can be corrected surgically. Here we focus on the contribution of acute cellular injury responses to the pathogenesis of osteoarthritis, with most of the data obtained from a non-invasive mouse model of ACL rupture to initiate OA. Cellular responses include a dramatic upregulation of primary response genes, including many degradative enzymes and inflammatory genes. The activation of these early response pathways leads to joint degradation, including proteolytic degradation and weakening of the cartilage matrix, which pre-disposes the joint to future OA. Targeting early cellular responses may therefore alter the trajectory of OA pathogenesis. I-16 CARTILAGE REPAIR AND THE SPRIFERMIN STORY: MECHANISMS, PRECLINICAL AND CLINICAL STUDY RESULTS, AND LESSONS LEARNED N. Muurahainen. EMD Serono Res. and Dev. Inst., Inc., Rockland, MA, USA Purpose: Sprifermin is a recombinant truncated form of human fibroblast growth factor 18 (rhFGF18) that is injected intra-articularly (i.a.). It is currently being investigated as a potential disease-modifying OA drug (DMOAD) in patients with knee OA. Nonclinical studies (in vitro and in vivo) have shown that sprifermin initially induces chondrocyte proliferation, which subsequently results in increased overall extracellular matrix production.
Methods: Two Phase 1 sprifermin clinical trials were conducted in which i.a. sprifermin injections were compared to i.a. placebo injections: (1) a First-in-Human (FiH) trial (clinicaltrials.gov NCT00911469) and (2) a proof-of-concept (PoC) Phase 1b trial (NCT01033994). The FiH trial was a randomized double-blind placebo-controlled (DBPC) trial that was performed in patients with severe knee OA who were scheduled for knee replacement (KR) within the next 6 months. It included single ascending dose (SAD) and multiple-ascending dose (MAD) cohorts. The primary endpoint was the safety of i.a. sprifermin both local and systemic, at sequentially increasing dose levels of sprifermin. Other endpoints included: circulating sprifermin levels and the histology and biomechanical properties of cartilage obtained at the time of KR surgery. The PoC trial was a 1-year DBPC trial performed in patients with Kellgren-Lawrence Grade 2-3 knee OA who were not anticipating KR. It also included SAD and MAD cohorts. The primary endpoint was cartilage thickness measured magnetic resonance imaging (MRI). Other endpoints included: safety, circulating sprifermin levels, joint space width on X-ray, and patient-reported symptoms on the Western Ontario MacMaster (WOMAC) questionnaire. Results: Both clinical trials demonstrated no major safety or injectionsite issues as related to sprifermin. In addition, after i.a. spifermin injections into the knee, circulating drug levels all remained below the limit of quantification. In the PoC trial, on sprifremin as compared to placebo, dose-dependent structural benefits were observed with respect to MRI total cartilage thickness and X-ray lateral joint space width. The WOMAC pain score improved in all patients, with less improvement at 12 months for patients who received 100 mg sprifermin compared to i.a. placebo. Conclusions: One lesson learned: a challenge to designing clinical trials of i.a. DMOADs is the known pain-reducing effect of i.a. placebo. Another challenge to development of DMOADs in general is that effects of a drug on multiple joint structures may be observed on MRI, but not on X-ray, the technology for the structural endpoint acceptable to regulators. An additional challenge to developing DMOADs is that OA is heterogeneous, such that no one DMOAD may treat all subtypes of OA. Ideally biomarkers may aid in the identification of different OA responder sub-types in the future. A 2-year Phase 2 doseranging DBPC trial of sprifermin is currently ongoing (NCT01919164). It will assess structure in all patients both by MRI and X-ray, evaluate symptoms via WOMAC and other patient-reported outcome measures, while also exploring the potential for future biomarker prediction of subjects who are clinical responders to treatment. Ideally, the results of the ongoing Phase 2 trial will confirm optimal dosing while replicating and positively extending the findings of the Phase 1 trials. I-17 ORGAN-SPECIFIC BLOOD VESSEL MORPHOGENESIS R. Adams y, z. y Univ. of Muenster, Muenster, Germany; z Max Planck Inst. for Molecular Biomedicine, Muenster, Germany Purpose: Angiogenesis is the main process mediating the expansion of the blood vessel network during development, tissue regeneration or in pathological conditions such as cancer. The formation of new endothelial sprouts, a key step in the angiogenic growth program, involves the selection of endothelial tip cells, which are highly motile, extend numerous filopodia, and lead new sprouts. Angiogenic sprouting is induced by tissue-derived, pro-angiogenic signals such as vascular endothelial growth factor (VEGF), which activates and triggers signaling by cognate receptor tyrosine kinases in the endothelium. However, this response is strongly modulated by intrinsic signaling interactions between endothelial cells, which involve the Notch pathway. Our work is providing further insight into the regulation of sprouting angiogenesis such as the distinct functional roles of different Notch ligands or the modulation of growth factor receptor activity by endocytosis. More recently, we found that blood vessel growth in bone involves a specialized, tissue-specific form of angiogenesis that is distinct from other organ systems. Notch signaling promotes endothelial cell proliferation and vascular growth in postnatal long bone, which is the opposite of the well-established function of Notch and its ligand Dll4 in the endothelium of other organs and tumors. We also found that Notch controls the release of angiocrine signals from the bone endothelium and thereby controls perivascular osteoprogenitor cells. Using a combination of inducible, cell type-specific mouse genetics and pharmacological
protein expression or miR-140 expression. The AcanKO and miR-140KO clones showed no change in cell growth. The AcanKO clones maintained the cartilage phenotype as demonstrated expression of chondrocyte marker genes, including, Col2a1, Col1a2, Matn1 and Comp. When injected subcutaneously in nude mice the RCS or RCS/Cas9 cell lines generated a chondrosarcoma with a fully cartilaginous matrix. In contrast the AcanKO cell line generated a much smaller tumor-like tissue with few chondrocyte-like cells and substantial infiltration of immune cells. The loss of miR-140 expression was consistent with the indel size and presence in the seed sequence. Expression of cartilage genes, Col2a1, Comp and Acan were reduced in the miR-140KO cells but this did not appear to be associated with loss of phenotype. Expression of the miR-140 host gene WWP2 was unaffected by the targeted mutations indicating that changes in cell function observed were not associated with changes in expression of the host gene. The mutations were shown to affect miRNA maturation. Gene array analysis surprisingly showed no change in those genes, Adamts5, Pdgfa, Dnpep, Sp1, Hdac4 and Igfpb1, previously suggested to be miR-140 targets. Conclusion: The cell line described and similar chondrocyte cell lines under development will enable utilization of the extensive and rapidly expanding scope of the CRISP/Cas9 system to characterize gene function in chondrocytes. Some of the capacities of the CRISPR/Cas9 system that include; the use of arrayed sgRNA libraries for the identification of genes essential for survival, proliferation or other specific chondrocyte functions such as suppression of terminal differentiation; and the identification of epigenomic mechanisms, including histone modification, for gene regulation will be discussed. I-11 NOVEL APPROACHES TO DELIVERY OF IA THERAPY IN OA A.J. Grodzinsky. MIT, Cambridge, MA, USA Purpose: Osteoarthritis affects individual joints making intraarticular (i.a.) therapy a desirable treatment option, yet simple i.a. injection remains inadequate because drugs are rapidly cleared from the joint space via the lymphatics or vasculature. We will focus on the range of current approaches involving the use of micro-and nano-particle drug carriers intended for sustained release of drugs in the joint, as well as novel methods by which drug carriers can be delivered directly inside cartilage. Methods for intra-cartilage delivery incorporating mechanisms for binding of drug carriers inside cartilage enables targeting of hondrocytes and ECM, and additionally enables cartilage to act as a depot for delivery to other adjacent joint tissues. I-12 MICRORNAS: THE ROLE OF MICRORNAS IN THE PATHOGENESIS, DETECTION AND TREATMENT OF OA I. Clark y, T.E. Swingler y, L.T. Le y, N. Crowe y, M.J. Barter z, G. Wheeler y, T. Dalmay y, D.A. Young z. y Univ. of East Anglia, Norwich, United Kingdom; z Newcastle Univ., Newcastle-upon-Tyne, United Kingdom This session will review the role of microRNAs in the molecular pathogenesis of osteoarthritis (OA). It will present data on the regulation of microRNAs by relevant factors and their impact on intracellular signalling. Key targets of microRNAs in OA will also be explored. MicroRNAs have also been reported as circulating biomarkers of disease, and the utility of this approach and how it informs on the functional role of microRNAs will be discussed. Finally, the potential for microRNAs to be used therapeutically and the hurdles which need to be overcome to do this will be addressed. The focus of the Clark lab has been on the role and function of microRNAs in cartilage, particularly miR-455, the miR-29 family, miR-140 and miR-3085. MicroRNA-455 is genomically located within an intron of COL27A1. Collagen XXVII is expressed in cartilage, suggesting function of the miR in this tissue. We initially described a role for miR-455 in TGFbeta signalling, but have more recently uncovered function in Wnt signalling and in the regulation of Sirt1. The miR-29 family have been well-researched and are known e.g. to regulate collagen gene expression, giving them a role in fibroses. We identified miR-29b as one of only two miRs which was regulated at an early time point after surgery in the murine DMM (‘destabilisation of the medial meniscus’) model of OA. Potential targets of miR-29 were regulated in the opposite direction to the miR, suggesting function. The
S3
miR-29 family were regulated in many models of chondrocyte differentiation and in human end-stage OA. In chondrocytes we have shown that miR-29 is negatively regulated by Sox9 and negatively regulates a number of key intracellular signalling pathways in OA. We have identified novel direct targets in the Wnt pathway and we have also shown that miR-29 directly targets a number of ADAMTS protease genes. We used RNA-Seq to explore the full range of miRs expressed by human articular chondrocytes from OA patients. This showed that the so-called passenger strand of miR-140, miR-140-3p was more highly expressed than the guide strand, miR-140-5p in newly isolated osteoarthritic chondrocytes. We have now shown that miR-140-3p directly targets a number of enzymes in the heparan sulphate proteoglycan synthesis pathway. These studies also identified miR-3085 in human chondrocytes. This miR had only previously been annotated in rodents where it was presumed intergenic. However, in man it is located in the final intron of the CRTAC1 gene, which codes for cartilage acidic protein 1. We have shown it to directly target ITGA5, the integrin alpha5 gene, but it also strongly induces interleukin-1 signalling in chondrocytes. I-13 GETTING EVIDENCE INTO PRACTICE: PRAGMATIC TRIALS AND IMPLEMENTATION RESEARCH K. Dziedzic. Keele Univ., Keele, United Kingdom The randomized controlled trial (RCT) is a versatile design that has evolved from studies of efficacy and proof of principle to pragmatic trials of clinical effectiveness and complex interventions. The RCT has formed the basis of evidence based practice and international treatment guidelines. Increasingly the design has been applied to studies of implementation where new models of care have been compared with usual care in whole system implementation e.g. MOSAICS (managing osteoarthritis in consultations) a cluster randomised controlled trial in primary care (1e7). In this context the implementation study seeks to promote the intervention as an alternative to usual care with engagement of key stakeholders (organisations, health care professionals, patients), and measures uptake of the new approach with assessment of its likely sustainability beyond the study. In addition to the usual challenges of cluster designs, the MOSAICS study will be used to highlight the following considerations: Use of theoretical frameworks to plan, understand and evaluate implementation The value of mixed methods Patient and public involvement in implementation research Selection of eligible trial participants Barriers and facilitators to implementation in primary care Fidelity to protocols in the context of wide variations in usual practice Ongoing engagement of control practices Determining outcomes of quality care Reporting findings References 1. Morden A, Ong BN, Brooks L, Jinks C, Porcheret M, Edwards JJ, Dziedzic KS. Introducing Evidence Through Research “Push”: Using Theory and Qualitative Methods. Qual Health Res. 2015 Nov;25(11):1560e75. 2. Morden A, Jinks C, Ong BN, Porcheret M, Dziedzic KS. Acceptability of a 'guidebook' for the management of Osteoarthritis: a qualitative study of patient and clinician's perspectives. BMC Musculoskelet Disord. 2014 Dec 13;15:427. 3. Edwards JJ, Jordan KP, Peat G, Bedson J, Croft PR, Hay EM, Dziedzic KS. Quality of care for OA: the effect of a point-of-care consultation recording template. Rheumatology (Oxford). 2015 May;54(5):844e53. 4. Dziedzic KS, Healey EL, Porcheret M, Ong BN, Main CJ, Jordan KP, Lewis M, Edwards JJ, Jinks C, Morden A, McHugh GA, Ryan S, Finney A, Jowett S, Oppong R, Afolabi E, Pushpa-Rajah A, Handy J, Clarkson K, Mason E, Whitehurst T, Hughes RW, Croft PR, Hay EM. Implementing the NICE osteoarthritis guidelines: a mixed methods study and cluster randomised trial of a model osteoarthritis consultation in primary care– the Management of OsteoArthritis In Consultations (MOSAICS) study protocol. Implement Sci. 2014 Aug 27;9:95. 5. Porcheret M, Main C, Croft P, McKinley R, Hassell A, Dziedzic K. Development of a behaviour change intervention: a case study on the practical application of theory. Implement Sci. 2014 Apr 3;9(1):42.
S4
Abstracts / Osteoarthritis and Cartilage 24 (2016) S1eS7
6. Ong BN, Morden A, Brooks L, Porcheret M, Edwards JJ, Sanders T, Jinks C, Dziedzic K. Changing policy and practice: making sense of national guidelines for osteoarthritis. Soc Sci Med. 2014 Apr;106:101e9. 7. Edwards JJ, Khanna M, Jordan KP, Jordan JL, Bedson J, Dziedzic KS. Quality indicators for the primary care of osteoarthritis: a systematic review. Ann Rheum Dis. 2015 Mar;74(3):490e8. 2):1371e8. I-14 DYNAMIC JOINT IMAGING IN HUMAN OA: ALTERED IN VIVO CARTILAGE FUNCTION AND EARLY ONSET OA L.E. DeFrate. Duke Univ. Med. Ctr., Durham, NC, USA Mechanical loading plays a critical role in maintaining the health and function of articular cartilage. Normal cartilage loading is believed to help maintain cartilage homeostasis, while altered cartilage loading (due to factors such as obesity, joint injury, and malalignment) is believed to play a role in the degradation of cartilage. Thus, understanding the local, in vivo mechanical environment of cartilage in response to normal and pathological conditions could provide critical insights into the mechanisms contributing to osteoarthritis. However, there is limited data characterizing the local mechanical environment of cartilage in vivo. While gait analysis studies provide important information characterizing the total load transferred through the joint, it may be difficult to predict the local tissue response of cartilage from these measurements. In this regard, magnetic resonance (MR) imaging techniques provide the potential to provide additional measurements of the changes in the morphology, deformation, and composition of cartilage in vivo to gain insights into the mechanisms leading to osteoarthritis. To this end, this talk will discuss recent advances in the measurement of in vivo cartilage function using MR imaging as well as biplanar radiography. These advances are likely to provide important information that to enhance our understanding of mechanisms predisposing the joint to the development and progression of osteoarthritis. Ultimately, understanding these mechanisms is important to developing new interventions aimed at the prevention of osteoarthritis. I-15 JOINT TISSUE BIOMECHANICAL ADAPTATION)
BIOMECHANICS: JOINT RESPONSES IMPACT (THEORIES OF GROWTH
TO AND
D.R. Haudenschild. Univ. of California Davis, Sacramento, CA, USA Purpose: Joint injury often leads to osteoarthritis. The goal of our research is to disconnect OA from joint injury, and to do so we examine the events upon injury that initiate OA pathogenesis. There is the obvious damage to the joint tissues caused by the immediate mechanical insult to the joint. Joint instability also contributes, although instability can be corrected surgically. Here we focus on the contribution of acute cellular injury responses to the pathogenesis of osteoarthritis, with most of the data obtained from a non-invasive mouse model of ACL rupture to initiate OA. Cellular responses include a dramatic upregulation of primary response genes, including many degradative enzymes and inflammatory genes. The activation of these early response pathways leads to joint degradation, including proteolytic degradation and weakening of the cartilage matrix, which pre-disposes the joint to future OA. Targeting early cellular responses may therefore alter the trajectory of OA pathogenesis. I-16 CARTILAGE REPAIR AND THE SPRIFERMIN STORY: MECHANISMS, PRECLINICAL AND CLINICAL STUDY RESULTS, AND LESSONS LEARNED N. Muurahainen. EMD Serono Res. and Dev. Inst., Inc., Rockland, MA, USA Purpose: Sprifermin is a recombinant truncated form of human fibroblast growth factor 18 (rhFGF18) that is injected intra-articularly (i.a.). It is currently being investigated as a potential disease-modifying OA drug (DMOAD) in patients with knee OA. Nonclinical studies (in vitro and in vivo) have shown that sprifermin initially induces chondrocyte proliferation, which subsequently results in increased overall extracellular matrix production.
Methods: Two Phase 1 sprifermin clinical trials were conducted in which i.a. sprifermin injections were compared to i.a. placebo injections: (1) a First-in-Human (FiH) trial (clinicaltrials.gov NCT00911469) and (2) a proof-of-concept (PoC) Phase 1b trial (NCT01033994). The FiH trial was a randomized double-blind placebo-controlled (DBPC) trial that was performed in patients with severe knee OA who were scheduled for knee replacement (KR) within the next 6 months. It included single ascending dose (SAD) and multiple-ascending dose (MAD) cohorts. The primary endpoint was the safety of i.a. sprifermin both local and systemic, at sequentially increasing dose levels of sprifermin. Other endpoints included: circulating sprifermin levels and the histology and biomechanical properties of cartilage obtained at the time of KR surgery. The PoC trial was a 1-year DBPC trial performed in patients with Kellgren-Lawrence Grade 2-3 knee OA who were not anticipating KR. It also included SAD and MAD cohorts. The primary endpoint was cartilage thickness measured magnetic resonance imaging (MRI). Other endpoints included: safety, circulating sprifermin levels, joint space width on X-ray, and patient-reported symptoms on the Western Ontario MacMaster (WOMAC) questionnaire. Results: Both clinical trials demonstrated no major safety or injectionsite issues as related to sprifermin. In addition, after i.a. spifermin injections into the knee, circulating drug levels all remained below the limit of quantification. In the PoC trial, on sprifremin as compared to placebo, dose-dependent structural benefits were observed with respect to MRI total cartilage thickness and X-ray lateral joint space width. The WOMAC pain score improved in all patients, with less improvement at 12 months for patients who received 100 mg sprifermin compared to i.a. placebo. Conclusions: One lesson learned: a challenge to designing clinical trials of i.a. DMOADs is the known pain-reducing effect of i.a. placebo. Another challenge to development of DMOADs in general is that effects of a drug on multiple joint structures may be observed on MRI, but not on X-ray, the technology for the structural endpoint acceptable to regulators. An additional challenge to developing DMOADs is that OA is heterogeneous, such that no one DMOAD may treat all subtypes of OA. Ideally biomarkers may aid in the identification of different OA responder sub-types in the future. A 2-year Phase 2 doseranging DBPC trial of sprifermin is currently ongoing (NCT01919164). It will assess structure in all patients both by MRI and X-ray, evaluate symptoms via WOMAC and other patient-reported outcome measures, while also exploring the potential for future biomarker prediction of subjects who are clinical responders to treatment. Ideally, the results of the ongoing Phase 2 trial will confirm optimal dosing while replicating and positively extending the findings of the Phase 1 trials. I-17 ORGAN-SPECIFIC BLOOD VESSEL MORPHOGENESIS R. Adams y, z. y Univ. of Muenster, Muenster, Germany; z Max Planck Inst. for Molecular Biomedicine, Muenster, Germany Purpose: Angiogenesis is the main process mediating the expansion of the blood vessel network during development, tissue regeneration or in pathological conditions such as cancer. The formation of new endothelial sprouts, a key step in the angiogenic growth program, involves the selection of endothelial tip cells, which are highly motile, extend numerous filopodia, and lead new sprouts. Angiogenic sprouting is induced by tissue-derived, pro-angiogenic signals such as vascular endothelial growth factor (VEGF), which activates and triggers signaling by cognate receptor tyrosine kinases in the endothelium. However, this response is strongly modulated by intrinsic signaling interactions between endothelial cells, which involve the Notch pathway. Our work is providing further insight into the regulation of sprouting angiogenesis such as the distinct functional roles of different Notch ligands or the modulation of growth factor receptor activity by endocytosis. More recently, we found that blood vessel growth in bone involves a specialized, tissue-specific form of angiogenesis that is distinct from other organ systems. Notch signaling promotes endothelial cell proliferation and vascular growth in postnatal long bone, which is the opposite of the well-established function of Notch and its ligand Dll4 in the endothelium of other organs and tumors. We also found that Notch controls the release of angiocrine signals from the bone endothelium and thereby controls perivascular osteoprogenitor cells. Using a combination of inducible, cell type-specific mouse genetics and pharmacological