Multiple Myeloma Related Bone Disease Research Articles

Expert consensus on a multidisciplinary approach for the management of multiple myeloma-related bone disease

Expert consensus on a multidisciplinary approach for the management of multiple myeloma-related bone disease

Th17 Cells Targeting By MiR-21 Inhibitor Impairs Multiple Myeloma Related Bone Disease

Bone disease (BD) represents a hallmark of multiple myeloma (MM), characterized by classical osteolytic lesions and/or osteoporosis, that can be life threatening and contribute to poor outcomes. The complex interplay among MM conditioned bone effectors such as MM cells, osteoclasts (OCLs) and osteoblasts within BM microenvironment (BMM) supports MMBD. Several studies have shown that the extent of BD is tightly correlated to Th17 cells development and maintenance. Th17 secrete pro OCL cytokines such as RANKL, TNF, and IL-17, contributing to MMBD development. Recent findings showed that microRNAs (miRNAs) are involved in MMBD. MiRNAs are short non-coding RNAs that regulate gene expression at a post transcriptional level. Among others, miR-21 is involved in Th17 differentiation by targeting SMAD-7, a negative regulator of TGF-β signaling, promoting the activation of SMAD-2/3, suppressing IL-2 expression, and ultimately enhancing the activity of the TGF-β signaling pathway. Taken together, these data support a therapeutic strategy of miR-21 targeting to ameliorate MMBD through Th17 inhibition. We have previously demonstrated that miR-21 activity within BMM plays a crucial role in bone resorption/apposition balance through PIAS3 suppression and STAT3 dependent RANKL transcription in BM stromal cells. In the present study, we sought to evaluate the role of miR-21 in Th17 mediated BD. We enriched Th17 from BM CD4+CCR6+ T cells and evaluated miR-21 levels. We found increased miR-21 in MM derived Th17 (MMTh17) as compared to controls, supporting the relevance of miR-21 in MMTh17. To further explore the mechanisms of miR-21 activity in Th17 function, freshly isolated naïve CD4+ T cells were differentiated from healthy donors into Th17 along 18 days of culture in the presence of polarizing cytokines. At the end of culture, T cells expressed the Th17 full maturation markers RORC and IL17. As a model of MMBD in vitro, OCL resorptive activity was evaluated on dentine discs with/without Th17 freshly isolated from MM patients or differentiated in vitro. In both cases, Th17 promoted potent OCL mediated dentin pits generation as compared to controls. To counteract miR-21 activity, we electroporated naïve CD4+ T cells with miR-21 inhibitor (miR21i) or scramble control mirna before starting Th17 differentiation culture. MiR-21 expression levels were assessed by rt pcr before and at the end of differentiation culture to ascertain its effective inhibition. To map signaling pathways differences elicited by miR21i-Th17, we performed a mass spectrometry-based quantitative phosphoproteomics analysis. 1134 phosphorylated proteins were identified, with 386 significant changes as compared to controls. The global-pairwise-normalized data underwent to Ingenuity Pathway Analysis (IPA). Interestingly, analysis showed a generally higher level of phosphoserine sites and top canonical pathways affected by miR-21 inhibition included PI3K/AKT and 14-3-3 Signaling. Among Th17 potential regulators, enhanced activity of PDCD4, STAT1, MINK1 and FOXO1 were observed, while ITGAL showed reduced activity. On these bases, we performed WB to validate IPA analysis and explored additional widely acknowledged Th17 regulators. Upon miR-21i treatment, the expression of PDCD4 and FOXO1 were significantly increased while lower levels of RORC were observed. Furthermore, PIAS3 and TBX21 were significantly upregulated in the presence of miR-21 antagonism. STAT3 is a master transcription factor for Th17 upon IL-6 stimulation. As PIAS3 and PDCA4 negatively regulate STAT3, we checked phospho-STAT3 expression and found it downregulated as expected. Overall, these data indicated that Th17 differentiation was impaired by miR-21i. In the second set of experiments, we aimed to evaluate Th17 functional impairment by miR-21 antagonism in MMBD. OCLs were plated with dentine discs and exposed to either Th17 alone, miR21i-Th17, or RANKL/MCSF cytokine alone as positive control. Dentine pits and areas were significantly lower in the presence of miR21i-Th17 as compared to Th17 alone and positive control (Fig.1). These data indicated that miR-21 antagonism negatively regulates Th17 mediated OCL activity and support the role of miR-21 inhibition as an innovative treatment tool in MMBD. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Treatment of multiple myeloma-related bone disease: recommendations from the Bone Working Group of the International Myeloma Working Group.

In this Policy Review, the Bone Working Group of the International Myeloma Working Group updates its clinical practice recommendations for the management of multiple myeloma-related bone disease. After assessing the available literature and grading recommendations using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) method, experts from the working group recommend zoledronic acid as the preferred bone-targeted agent for patients with newly diagnosed multiple myeloma, with or without multiple myeloma-related bone disease. Once patients achieve a very good partial response or better, after receiving monthly zoledronic acid for at least 12 months, the treating physician can consider decreasing the frequency of or discontinuing zoledronic acid treatment. Denosumab can also be considered for the treatment of multiple myeloma-related bone disease, particularly in patients with renal impairment. Denosumab might prolong progression-free survival in patients with newly diagnosed multiple myeloma who have multiple myeloma-related bone disease and who are eligible for autologous stem-cell transplantation. Denosumab discontinuation is challenging due to the rebound effect. The Bone Working Group of the International Myeloma Working Group also found cement augmentation to be effective for painful vertebral compression fractures. Radiotherapy is recommended for uncontrolled pain, impeding or symptomatic spinal cord compression, or pathological fractures. Surgery should be used for the prevention and restoration of long-bone pathological fractures, vertebral column instability, and spinal cord compression with bone fragments within the spinal route.

Disparities in Healthcare Resource Utilization for Multiple Myeloma

▪Background: Nearly half of older African-Americans who develop multiple myeloma (MM) do not receive systemic treatment. Those who do are less likely to receive newer treatments, such as novel agents and stem cell transplant, than their peers. In this study, we sought to determine if disparities in resource utilization exist even among patients receiving similar treatment.Methods: All newly diagnosed MM cases from 2007-2013 in the SEER-Medicare dataset were reviewed along with their corresponding claims data through 2014. We excluded cases 1) not enrolled in Medicare Part A, B, and D; 2) HMO enrollees; 3) those diagnosed prior to age 65; 4) all patients who did not receive a proteasome inhibitor and/or an immunomodulatory drug within 6 months; 5) those who underwent stem cell mobilization or transplantation; or 6) died within 12 months of MM diagnosis. All reported medical costs including both those paid by Medicare and patient copays for the first 12 months post-diagnosis were captured and adjusted for inflation.Results: 2,841 patients were included. The median age was 74 at diagnosis (range 65-96) and 51% were male. 79% (n = 2,247) were white, 14% (n = 403) African-American/Black, and 7% (n = 191) were another race. Overall, the median expenditure was $127,054 in the 12 months post-diagnosis; $121,400 for African-Americans, $127,810 for whites, and $119,209 for other races.After controlling for age, gender, comorbidities, a proxy measure of performance status, and MM related renal impairment and bone disease, African-American patients had $10,524 less in overall expenditures on average than white patients. This can partly be attributed to lower expenditures on MM drugs. On average African-American patients had $5,520 less in MM drug expenditures (p = 0.0062). African-Americans also had 9.3 less days of interaction with outpatient services compared to their white peers (p < 0.0001), but 4.6 more days in inpatient settings (p = 0.0208).There was no statistically significant difference between white patients and patients of races other than white or African-American in overall expenditure or MM drug expenditure but members of other races had 8.2 less days of interaction with outpatient services (p = 0.0004) and 5.7 less days in inpatient settings (p = 0.0350).The estimated median overall survival for African-American patients was 44 months (95% CI 40-51) compared to 47 (45-50) for white patients and 57 (44-66) for patients of other races (p = 0.097). Race was not associated with overall survival in multivariate analysis.Conclusion: Minority patients with MM received fewer services during the 12 months post-diagnosis. It is currently unclear if this is due to inferior care, overuse among white patients, or related to the clinical needs of the patients. DisclosuresSchroeder:Amgen Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees. Vij:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Jansson: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharma: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Multiple Myeloma-Related Bone Disease: State-of-Art and Next Future Treatments

SUMMARY Multiple myeloma (MM) is a plasma cell malignancy associated with the development of life-threatening and/or severe osteolytic lesions, which significantly worsen the quality of life of affected patients. MM-related bone disease (BD) is the result of an overwhelming osteoclastic activity, while osteoblast-mediated bone formation is inhibited. Bisphosphonates are still the mainstay of therapy for BD. However, these drugs are associated with mid long-term sequelae. In this work, we review the pathogenesis and currently available therapies of MM-related BD. We describe the most recent and promising findings that may translate in changing the clinical practice in the next future.

A Systematic Review of MRI, Scintigraphy, FDG-PET and PET/CT for Diagnosis of Multiple Myeloma Related Bone Disease - Which is Best?

The purpose of the current study was to conduct a systematic review of the published literature to evaluate the diagnostic accuracy of FDG-PET, PTE/CT, MRI and scintigraphy for multiple myeloma related bone disease. Through a search of PubMed, EMBASE, and the Cochrane Library, two reviewers independently assessed the methodological quality of each study. We estimated pooled sensitivity, specificity, positive and negative likelihood ratios (PLR and NLR), and two sample Z-tests were conducted to evaluate for differences in sensitivity, specificity, area under the curve (AUC), and the Q* index between any two diagnostic modalities. A total of 17 studies were reviewed. The MRI had a pooled sensitivity of 0.88, specificity of 0.68, AUC of 0.897, and Q*index of 0.828, whereas for MIBI, the corresponding values were 0.98, 0.90, 0.991, and 0.962, respectively, and for bone scan, they were 066, 0.83, 0.805, and 0.740, respectively. The corresponding values of MIBI were 0.98, 0.90, 0.991, and 0.962, respectively. For PET and PET/CT, the values were 0.91, 0.69, 0.927 and 0.861, respectively. Statistically significant differences were not found in the sensitivity, specificity, AUC, and Q* index between MRI, scintigraphy, FDG-PET and PET/CT. On the condition that X ray is taken as a reference in our study, we suggested that FDG-PET, PTE/CT, MRI and scintigraphy are all associated with high detection rate of bone disease in patients with MM. Thus, in clinical practice, it is recommended that we could choose these tests according to the condition of the patient.

Comparison of modern and conventional imaging techniques in establishing multiple myeloma‐related bone disease: a systematic review

This systematic review of studies compared magnetic resonance imaging (MRI), (18) F-fluorodeoxyglucose positron emission tomography (FDG-PET), FDG-PET with computerized tomography (PET-CT) and CT with whole body X-Ray (WBXR) or (whole body) CT in order to provide evidence-based diagnostic guidelines in multiple myeloma bone disease. A comprehensive search of 3 bibliographic databases was performed; methodological quality was assessed using Quality Assessment of Diagnostic Accuracy Studies (QUADAS) criteria (score 1-14). Data from 32 directly comparative studies were extracted. The mean QUADAS score was 7·1 (3-11), with quality hampered mainly by a poor description of selection and execution criteria. All index tests had a higher detection rate when compared to WBXR, with up to 80% more lesions detected by the newer imaging techniques; MRI (1·12-1·82) CT (1·04-1·33), PET (1·00-1·58) and PET-CT (1·27-1·45). However, the modern imaging techniques detected fewer lesions in the skull and ribs. In a direct comparison CT and MRI performed equally with respect to detection rate and sensitivity. This systematic review supports the International Myeloma Working Group guidelines, which recommend that WBCT can replace WBXR. In our opinion, the equal performance of MRI also indicates that it is a valuable alternative. As lesions of the skull and ribs are underdiagnosed by modern imaging techniques we advise additional X-rays of these regions. The consequences of this approach are discussed.

Abstract 2142: The nuclear export protein CRM1 (XPO1) regulates multiple myeloma cell growth, osteoclastogenesis, and myeloma-induced osteolysis.

Abstract The key nuclear export protein CRM1 (chromosomal region maintenance 1, Exportin 1, XPO1) may directly contribute to the pathophysiology of human multiple myeloma (MM). Here, we characterized the role of CRM1 in MM biology and defined the efficacy and molecular mechanisms of novel oral, irreversible, selective inhibitors of nuclear export (SINEs) targeting CRM1 against MM. CRM1 is significantly elevated in patient MM vs. normal plasma cells at transcript and protein levels. CRM1 downregulation by shCRM1 lentiviruses inhibited cell growth and survival of MM cells (p&amp;lt; 0.01). Importantly, SINEs (KPT-185, KPT-251, KPT-276, and KPT-330) blocked proliferation and decreased survival of MM cell lines and patient MM cells (LD50 2-log differences). SINEs potently enhanced nuclear accumulation of multiple CRM1 cargo tumor suppressor proteins, including rapid induction of p53 and IκB (as early as 2h after drug treatment) followed by FOXO1A, FOXO3A, p27, and PP2A in MM cells. Transcripts of p53 and its downstream targets (p21, PUMA, BAX) were induced by KPT-185, thereby inducing strong growth arrest and apoptosis. KPT-185 decreased MM oncogenes (c-myc, c-maf), anti-apoptosis molecules Mcl-1 and Bcl-xL; increased pro-apoptotic protein BAX; as well as inhibited pIκBα. Inhibition of pIκBα further correlated with KPT-185-blocked NFκB p65 DNA-binding activity in MM cells with or without A Proliferation-Inducing Ligand (APRIL) stimulation. KPT-185 further downregulated CRM1 protein, which was blocked by bortezomib; concurrently, KPT-185 (or KPT-330) upregulated CRM1 mRNA in MM cells. Cleavage of caspase 3 and PARP was markedly increased in MM1R cells treated with KPT-185 and bortezomib vs. either drug alone, confirming enhanced cytotoxicity by combination of these agents. Combined dex with KPT-185 (or KPT-276) induced synergistic cytotoxicity against MM cells (combination indices &amp;lt; 1). Moreover, KPT-185 and KPT-330 impaired osteoclastogenesis and bone resorption via blockade of RANKL-induced NFκB activation and NFATc1 in OC precursor cells, without impacting osteoblasts and BMSCs. Finally, SINEs (KPT-251 and KPT-276) suppressed MM cell growth (p&amp;lt; 0.01), diminished MM cell-induced osteolysis, and prolonged survival of SCID mice with diffuse human MM bone lesions. Together, these results identify CRM1 as a promising novel target in MM, strongly supporting clinical development of SINE CRM1 inhibitors to inhibit both MM cell growth and related bone disease. The oral SINE KPT-330 is ongoing in MM and other hematological malignancies. Citation Format: Yu-Tzu Tai, Yosef Landesman, Chirag Acharya, Yolanda Calle, Mike Zhong, Michele Cea, Daniel Tannenbaum, Antonia Cagnetta, Michaela Reagan, Aditya Munshi, William Senapedis, Jean-Richard Saint-Martin, Trinayan Kashyap, Sharon Shacham, Michael Kauffman, Yumei Gu, Lizi Wu, Steve Schey, Irene Ghobrial, Andrew Kung, Nikhil Munshi, Paul Richardson, Kenneth Anderson, Haoqiang Ying. The nuclear export protein CRM1 (XPO1) regulates multiple myeloma cell growth, osteoclastogenesis, and myeloma-induced osteolysis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2142. doi:10.1158/1538-7445.AM2013-2142

Incidence of skeletal morbidity rates over time in patients with multiple myeloma-related bone disease as reported in randomized trials employing bone-modifying agents

The purpose of this review was to investigate if advances in bone-targeted therapies have decreased the incidence of skeletal morbidity rates over time in patients with multiple myeloma-related bone disease. A literature search was conducted over the OvidSP platform in MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials to identify Phase III results from bone-targeted therapy trials in patients with multiple myeloma. The skeletal morbidity rate was the end point of interest, and for each study, a mean year of enrollment ([start of enrollment + end of enrollment]/2) was calculated. A total of eight study arms were identified, with only two placebo arms; therefore, a weighted linear regression was not feasible and only intervention treatment arms were analyzed. A statistically significant downward trend in the skeletal morbidity rate was observed in all intervention arms. The incidence of skeletal morbidity rates has decreased significantly over time in patients with multiple myeloma.

CRM1 Blockade by Novel Inhibitors of Nuclear Export (SINEs) Inhibits Multiple Myeloma Cell Growth, Osteoclastogenesis, and Myeloma-Induced Osteolysis

AbstractAbstract 326The key nuclear export protein CRM1 (chromosome region maintenance 1, Exportin 1, XPO1) may directly contribute to the pathophysiology of human multiple myeloma (MM). Here, we characterized the role of CRM1 in MM biology and defined molecular mechanisms whereby novel oral, irreversible, selective inhibitors of nuclear export (SINE) targeting CRM1 mediate anti-MM activity. CRM1 gene expression is increased with disease progression, since it is significantly elevated in active MM and plasma cell leukemia (PCL) vs. normal/MGUS/SMM patients (p< 0.02). CRM1 downregulation by shCRM1 lentiviruses significantly decreases MM cell viability regardless of drug sensitivity and p53 status. Importantly, SINE (KPT-185, KPT-251, KPT-276, and KPT-330) specifically blocked proliferation and decreased survival of MM cell lines (n=14) and patient MM cells (n=17) (LD50 < 200 nM), cultured alone and with bone marrow stromal cells (BMSCs) or osteoclasts. Caspases 3, 8, and 9 were not induced by any SINE in BMSCs derived from MM patients, cultured either alone or with MM cells, under conditions inducing marked apoptosis of MM cells (>2-log differences). These agents potently enhanced nuclear accumulation of multiple CRM1 cargo tumor suppressor proteins p53, IκB, FOXO1A, FOXO3A, p27, and PP2A in MM cells. Transcripts of p53 and its downstream targets p21, PUMA, BAX were also induced by KPT-185, thereby inducing strong growth arrest and apoptosis. KPT-185 decreased MM oncogenes (c-myc, c-maf), anti-apoptosis molecules Mcl-1 and BCL-xL; increased pro-apoptotic protein BAX; as well as inhibited HSP70 and pIkBa. KPT-185 further blocked baseline and APRIL-induced NFkB p65 DNA-binding activity in MM cells. It triggered proteasome-dependent reduction of CRM1 protein; concurrently, KPT-185 and KPT-330 upregulated CRM1 mRNA. Furthermore, KPT-185 induced a number of tumor suppressing, regulatory, apoptotic and anti-inflammatory genes, i.e., p53, p21, PUMA, BAX, CHOP, C10orf10, MIC1, IκBα in MM1S cells in a dose-dependent manner, regardless of the presence of BMSCs. Cleavage of caspase 3 and PARP was markedly increased in MM1R cells treated with KPT-185 and bortezomib vs. either drug alone, validating that the combination of these agents triggered stronger cytotoxicity against MM cells. Combined treatment with dex and KPT-185 (or KPT-276) induced synergistic cytotoxicity against MM cells. Moreover, KPT-185 and KPT-330 impaired osteoclastogenesis and bone resorption via blockade of RANKL-induced NFκB activation in osteoclast precursor cells, without impacting osteoblasts and BMSCs (Abstract#48190). Importantly, SINEs (KPT-251 and KPT-276) suppressed MM cell growth (p< 0.01), diminished MM cell-induced osteolysis, and prolonged survival of SCID mice with diffuse human MM bone lesions (p=0.0004). Together, these results identify CRM1 as a promising novel target in MM, strongly supporting clinical development of SINE CRM1 antagonists to inhibit both MM cell growth and related bone disease. Disclosures:Landesman:Karyopharm Therapeutics Inc: Employment. Senapedis:Karyopharm Therapeutics Inc: Employment. Saint-Martin:Karyopharm Therapeutics Inc: Employment. Kashyap:Karyopharm Therapeutics Inc: Employment. Ying:Karyopharm Therapeutics Inc: Employment. McCauley:Karyopharm Therapeutics Inc: Employment. Shacham:Karyopharm Therapeutics: Employment. Kauffman:Karyopharm Therapeutics Inc: Employment. Munshi:Celgene: Consultancy; Millenium: Consultancy; Merck: Consultancy; Onyx: Consultancy. Richardson:Millenium Pharmaceuticals: Membership on an entity’s Board of Directors or advisory committees; Celgene Corporation: Membership on an entity’s Board of Directors or advisory committees; Novartis Pharmaceuticals: Membership on an entity’s Board of Directors or advisory committees; Johnson & Johnson: Membership on an entity’s Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity’s Board of Directors or advisory committees. Anderson:Celgene, Millennium, BMS, Onyx: Membership on an entity’s Board of Directors or advisory committees; Acetylon, Oncopep: Scientific Founder, Scientific Founder Other.

Mir-29b Negatively Regulates Osteoclastic Cell Differentiation and Function: Implications for the Treatment of Multiple Myeloma-Related Bone Disease

AbstractAbstract 3960Overwhelming osteoclast (OCL) activation plays a central role in multiple myeloma (MM)-related bone disease. It is well known that in MM, OCL differentiation and final maturation rely upon RANKL stimulation by bone marrow mesenchymal cells and osteoblasts (OBLs). The clinical relevance of this pathway has been recently underlined by the anti-resorptive activity mediated by the mAb Denosumab.Since the discovery of microRNAs (miRNAs), findings on their role on intracellular pathway control have undergone a tremendous progress suggesting their potential use as a therapeutic tool against specific targets.Based on these premises, we aimed to identify miRNAs that can be relevant for the management of MM-related bone disease.Among miRNAs deregulated in MM, miR-29 family has been implicated in bone pathophysiology. Indeed, miR-29 family promotes OBL generation, while miR-29b might interfere with OCL differentiation and function by targeting RANKL axis and Metalloproteinase II (MMP2), that confers the property to degradate type I collagens.Therefore, we studied whether miR-29b can have a detrimental effect for terminally differentiated OCLs.We generated OCLs in vitro upon RANKL/MCSF stimulation starting from CD14+ hematopoietic precursors and found that miR-29b levels decline along OCL differentiation, reaching statistical significance as compared with its precursors (p=0,013). These data suggested that terminally differentiated OCLs do not require miR-29b. In order to assess whether miR-29b reconstitution could affect OCL activity, we transduced OCLs with a miR-29b coding sequence- carrying lentiviral vector (29b OCLs) or an empty lentiviral vector (eOCLs) and evaluated them in morphological and functional assays. As we expected, 29b OCLs showed a faint and irregular expression of tartrate acid phosphatase (TRAcP), which is highly and uniformously distributed within WT/eOCLs. Furthermore, when 29b OCLs were seeded on dentin, generation of lacunae on dentin surface, which recapitulates bone resorption, was significantly reduced as compared with WT/eOCLs (see Figure). According to these results, we measured the release of type I collagen fragments by OCLs and found that degradation of type I collagens was significantly impaired in 29b OCLs, suggesting that constitutive expression of miR-29b strongly antagonizes OCL differentiation and bone lytic functions.In order to reproduce the features of MM related bone disease, we co-cultured OCLs with RPMI-8226 MM cells, which are able to stimulate WT/eOCLs to generate lacunae on dentin slices in the absence of exogenous RANKL/MCSF. We observed that 29b OCLs failed to generate comparable numbers and areas of the pits in presence of MM cells (p=0,035/p=0,04).To support these functional data and ascertain the effects of miR-29b on specific pathways, we evaluated the expression of SP1 and NFATc-1, which are relevant transcription factors for OCL differentiation and work through RANK-L axis. We found that both factors are down-modulated in 29b OCLs as compared to WT/eOCLs. Down modulation was observed also for MMP2, thus mirroring the reduced capability to lyse type I collagens.Overall, our data indicate that miR-29b impairs OCL differentiation and function even in presence of robust stimuli such as RANKL and MCSF. We provided molecular support to these functional data, showing that SP1 and NFATc are down modulated in presence of miR-29b as well as MMP2, which is involved in collagen degradation. Intriguingly, MM cells, which represent a strong pro-osteoclastic factor, were not able to revert OCL functional impairment. We believe that these relevant preclinical findings allow to propose miR-29b mimics as a suitable and attractive candidate to be developed as a novel and innovative treatment of MM-related bone disease. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Challenging the Current Approaches to Multiple Myeloma-Related Bone Disease: From Bisphosphonates to Target Therapy

Bone disease (BD) is the hall-mark clinical feature of multiple myeloma (MM), accounting up to 60% of patients with bone pain at diagnosis and 60% with a pathologic fracture during the course of their disease. Experimental models, which recapitulate in vivo the human bone marrow microenvironment (HBMM) in immunodeficient mice have been recently developed as valuable tool for the study of MM pathophysiology as well as the experimental treatment of BD. At present, bisphosphonates are the mainstay treatment of MM-related BD. The growing information on the cellular and molecular bases of BD as well as the availability of novel anti-resorptive agents, such as the IgG1-anti-RANKL (AMG 161) Denosumab, are now depicting a new scenario where the treatment will be afforded by the use of different agents. Furthermore the availability of highthroughput molecular profiling approaches, including DNA microarrays and proteomics, is likely to provide new platforms for patients stratification and treatment individualization on specific targets. It is now the right time for a therapeutical approach which is rationally based on the complexity of the biopathology of MM-related BD.

Promoting Osteoblastogenesis Using a Novel Dkk-1 Neutralizing Antibody in the Treatment of Multiple Myeloma Related Bone Disease

Treatment of bone disease in multiple myeloma (MM) has largely focussed on the osteoclast axis while the osteoblast axis has been underexploited. Dkk1, an inhibitor of the wingless int (wnt) pathway, is important in osteoblastogenesis. Increased expression of Dkk1 in a subset of MM patients and its association with lytic bone disease opens up the potential of targeting the osteoblast axis. The aim of this study was to test the effect of a Dkk-1 neutralizing chimeric antibody (Mab B3) on osteoblasts (OB), osteoclasts (OC) and MM cells in the context of the bone microenvironment. First, we tested the expression of Dkk1 in plasma and bone marrow of 16 MM patients and 10 MM cell lines. Dkk1 levels were >18 ng/mL in 2 out of 16 patients; levels were comparable in blood and bone marrow plasma. In contrast, very little Dkk1 (2–9 ng/ml) was produced by bone marrow stromal cells (BMSC). One out of 10 MM cell lines (INA-6) expressed low concentrations of Dkk1 in the supernatant. Next, we tested the effect of Mab B3 on MM cell lines, in the presence or absence of BMSC, and on OB and OC from MM patient derived bone marrow. The effects on OC were evaluated by TRAP staining and pit formation. Effects on OB were assayed by alkaline phosphatase staining and alizarin red assays for calcium deposition. Mab B3 treatment did not demonstrate direct cytotoxic effects on MM cell lines negative for Dkk1. Mab B3, however, enhanced OB differentiation and calcium deposition in a dose dependent manner and inhibited OC differentiation and function, as evidenced by a decrease in number of multinucleated TRAP+ cells and a decrease in pit formation. Ongoing studies are addressing the effect of Mab B3 on MM cells in the context of OC and OB. Mab B3 is also undergoing in vivo testing in a SCID-hu model bearing INA-6 MM cells. These studies and the underlying mechanism of action of Mab B3 will be presented. Our preliminary data suggests that Mab B3 has anabolic bone effects; a corresponding human monoclonal antibody may be useful for the treatment of MM related bone disease. Future studies will evaluate Mab B3 in combination with catabolic agents such as bisphosphonates with the goal of restoring normal bone homeostatsis.