Myeloma bone disease

Transoral balloon kyphoplasty in a myeloma patient with painful osseous destruction of the corpus vertebrae axis

Multiple myeloma is the most common primary malignant disease of the spine, which can lead to pathological fractures with consecutive instability and immobilizing pain, due to osseous destruction of individual vertebral bodies. The different surgical care is challenging, although good stabilization should be achieved if possible. The resulting blocking of micro-movements leads to pain minimization. However, this is a symptomatic therapy and does not address the primary disease. In the following, we report on successful transoral balloon kyphoplasty for the treatment of myeloma-related osteolysis with a pathological fracture of vertebral body C2, which led to a significant clinical improvement.

Causal relationships between inflammatory factors and multiple myeloma: A bidirectional Mendelian randomization study

Changes in serum inflammatory factors occur throughout the onset and multiple myeloma (MM) progression, the feedback loops make it harder to distinguish between causes and effects. In the present study, we performed a bidirectional summary-level Mendelian randomization (MR) analysis to elucidate the causal relationships of C-reactive protein (CRP) and inflammatory regulators with MM. Summary-level data of genetic variants associated with inflammation were extracted from two genome-wide association studies (GWASs) on CRP and human cytokines, while data on MM was from large meta-analyses of GWASs among 372 617 UK Biobank participants. The inverse-variance weighted (IVW) method was used as the primary MR analysis and MR-Egger, weighted median, and MR-pleiotropy residual sum and outlier (MR-PRESSO) were used as the sensitivity analyses. Our results suggested that higher levels of monocyte-specific chemokine-3 (IVW estimate odds ratio [OR_IVW ] per SD genetic cytokines change: 1.24; 95% confidence interval [CI]: 1.03-1.49; P = .02), vascular endothelial growth factor (1.14, 1.03-1.27; P = .02), interleukin-10 (1.33, 1.01-1.75; P = .04) and interleukin-7 (1.24, 1.03-1.48; P = .02) were associated with increased risk of MM, while lower levels of tumor necrosis factor-β (0.84, 0.74-0.92; P < .001) was strongly associated with an increased risk of MM. And conversely, genetically predicted MM was related to increased levels of interleukin-17 (IVW estimate β: 0.051, 95% CI: 0.018-0.085; P = 2.7 × 10^-3 ). Besides, we observed no such significant associations for other inflammatory factors in our study. Overall, our study provides genetic evidence on the relationships of CRP and systemic inflammatory regulators with MM. Targeted interventions of specific inflammatory factors may have implications to alleviate MM cancer risk.

A cross-sectional observational study of health-related quality of life in adults with multiple myeloma

BACKGROUND

The purpose of this manuscript is to describe health-related quality of life (HRQoL) outcomes in a United States (US)-based sample of multiple myeloma (MM) patients and identify characteristics associated with poor HRQoL.

PATIENTS AND METHODS

MM patients identified through the Tumor Registry of a Southeastern US medical center were mailed surveys assessing patient characteristics and HRQoL outcomes. HRQoL outcomes were measured using PROMIS short form instruments which included measures of global health (global physical health and global mental health), physical function, and ability to participate in social roles and activities (social function). HRQoL domain scores were summarized, and best subset linear regression was used to identify predictors of HRQoL.

RESULTS

A total of 690 patients completed and returned surveys for a response rate of 64.7%. Respondents reported global physical health (44.9), global mental health (47.5), and physical function (44.1) significantly worse than the general population mean of 50 (p < .0001). Social function (49.5) did not differ significantly (p = .09). Worse socioeconomic status, higher comorbidities, not being in remission, and past receipt of radiation therapy were significantly associated with worse HRQoL. Treatment status and time since diagnosis were not associated with HRQoL outcomes.

CONCLUSIONS

Patients with MM have significantly worse HRQoL than the general population. These findings warrant increased attention from clinicians and researchers. More research is needed to better describe the relationship between treatment patterns and HRQoL in patients with MM, and to identify effective interventions.

Clonazepam for pain due to muscle spasm in a patient with vertebral compression fractures caused by multiple myeloma: a case report

Background

Vertebral compression fractures can cause severe back pain. Although many types of analgesics and interventional treatments are available, they are sometimes ineffective in mitigating the pain. We encountered a case where clonazepam was effective for the management of severe low back pain caused by lumbar vertebral compression fractures.

Case presentation

A 44-year-old male was diagnosed with multiple myeloma and had vertebral compression fractures of the first and second lumbar vertebrae. He had been suffering from severe low back pain on movement with muscle spasm and pain-associated anxiety. We considered this breakthrough low back pain to be caused by facet joint pain; thus, we prescribed clonazepam as a muscle relaxant and anxiolytic. Following this treatment, the intractable breakthrough pain was dramatically relieved.

Conclusion

Clonazepam, which has both muscle relaxant and anxiolytic effects, might be helpful in mitigating pain, associated anxiety, and muscle spasms due to vertebral compression fractures.

Role of vertebroplasty and balloon kyphoplasty in pathological fracture in myeloma: a narrative review

BACKGROUND

Up to 70% of multiple myeloma (MM) patients develop vertebral metastasis and subsequent pathological vertebral fractures (PVF). With contemporary systemic therapies, life expectancy of MM patients has improved drastically, and the need to manage pain and associated disability from PVF is increasingly a high priority. The aim of this review is to provide an updated comprehensive synthesis of evidence in the use of vertebral augmentation, including percutaneous vertebroplasty (PV) and balloon kyphoplasty (BKP), to treat MM-related PVF.

METHODS

A comprehensive multi-database search in accordance with PRISMA guidelines was performed up to 10 February 2021. Relevant English language articles were selected and critically reviewed.

FINDINGS

A total of 23 clinical studies have been included in the review. PV and BKP showed significant pain and functional improvements in terms of analgesia requirements, Cervical Spine Function Score, Eastern Cooperative Oncology Group scale, EQ-5D score, Karnofsky score, Neck Pain Disability Index, Oswestry Disability Index, Short form-36 (SF-36) questionnaire and VAS pain scale. Both procedures also reported promising radiographic outcomes in terms of vertebral height improvement, maintenance and restoration, as well as kyphotic deformity correction. Asymptomatic cement leakage was commonly reported. There was no significant difference between the two procedures.

CONCLUSION

PV and BKP are safe and effective procedure that offers pain relief, reduction in pain associated disability and reduction of fracture incidence. Its minimally invasive approach is associated with minimal morbidity risk, making it a viable option in frail patients.

LEVEL OF EVIDENCE IV

Narrative review.

Management of Myeloma Bone Lesions

Multiple myeloma (MM) is a B-cell neoplasm characterized by clonal plasma-cell proliferation. The survival and prognosis of this condition have been significantly improved by treatment with active anti-MM drugs such as bortezomib or lenalidomide. Further, the discovery of novel agents has recently paved the way for new areas of investigation. However, MM, including myeloma-related bone diseases, remains fatal. Bone disease or bone destruction in MM is a consequence of skeletal involvement with bone pain, spinal cord compression, and bone fracture resulting from osteolytic lesions. These consequences affect disease outcomes, including patients' quality of life and survival. Several studies have sought to better understand MM bone disease (MBD) through the classification of its molecular mechanisms, including osteoclast activation and osteoblast inhibition. Bisphosphonates and the receptor activator of the nuclear factor-kappa B (NF-κB) ligand (RANKL) inhibitor, denosumab, prevent skeletal-related events in MM. In addition, several other bone-targeting agents, including bone-anabolic drugs, are currently used in preclinical and early clinical evaluations. This review summarizes the current knowledge of the pathogenesis of MBD and discusses novel agents that appear very promising and will soon enter clinical development.

Metal Nanoparticles Released from Dental Implant Surfaces: Potential Contribution to Chronic Inflammation and Peri-Implant Bone Loss

Peri-implantitis is an inflammatory disease affecting tissues surrounding dental implants. Although it represents a common complication of dental implant treatments, the underlying mechanisms have not yet been fully described. The aim of this study is to identify the role of titanium nanoparticles released form the implants on the chronic inflammation and bone lysis in the surrounding tissue. We analyzed the in vitro effect of titanium (Ti) particle exposure on mesenchymal stem cells (MSCs) and fibroblasts (FU), evaluating cell proliferation by MTT test and the generation of reactive oxygen species (ROS). Subsequently, in vivo analysis of peri-implant Ti particle distribution, histological, and molecular analyses were performed. Ti particles led to a time-dependent decrease in cell viability and increase in ROS production in both MSCs and FU. Tissue analyses revealed presence of oxidative stress, high extracellular and intracellular Ti levels and imbalanced bone turnover. High expression of ZFP467 and the presence of adipose-like tissue suggested dysregulation of the MSC population; alterations in vessel morphology were identified. The results suggest that Ti particles may induce the production of high ROS levels, recruiting abnormal quantity of neutrophils able to produce high level of metalloproteinase. This induces the degradation of collagen fibers. These events may influence MSC commitment, with an imbalance of bone regeneration.

Systemic Dysfunction of Osteoblast Differentiation in Adipose-Derived Stem Cells from Patients with Multiple Myeloma

Multiple myeloma is characterized by bone lesions linked to increased osteoclast and decreased osteoblast activities. In particular, the osteoblast differentiation of bone marrow-derived stem cells (MSC) is impaired. Among the potential therapeutic tools for counteracting bone lesions, adipose-derived stem cells (ASC) could represent an appealing source for regenerative medicine due to their similar characteristics with MSC. Our study is among the first giving detailed insights into the osteoblastogenic capacities of ASC isolated by fat aspiration from myeloma patients (MM-ASC) compared to healthy subjects (HD-ASC). We showed that MM-ASC and HD-ASC exhibited comparable morphology, proliferative capacity, and immunophenotype. Unexpectedly, although normal in adipocyte differentiation, MM-ASC present a defective osteoblast differentiation, as indicated by less calcium deposition, decreased alkaline phosphatase activity, and downregulation of RUNX2 and osteocalcin. Furthermore, these ASC-derived osteoblasts displayed enhanced senescence, as shown by an increased β-galactosidase activity and cell cycle inhibitors expression (p16^INK4A, p21^WAF1/CIP1.), associated with a markedly increased expression of DKK1, a major inhibitor of osteoblastogenesis in multiple myeloma. Interestingly, inhibition of DKK1 attenuated senescence and rescued osteoblast differentiation, highlighting its key role. Our findings show, for the first time, that multiple myeloma is a systemic disease and suggest that ASC from patients would be unsuitable for tissue engineering designed to treat myeloma-associated bone disease.

The role of cement augmentation with percutaneous vertebroplasty and balloon kyphoplasty for the treatment of vertebral compression fractures in multiple myeloma: a consensus statement from the International Myeloma Working Group (IMWG)

Multiple myeloma (MM) represents approximately 15% of haematological malignancies and most of the patients present with bone involvement. Focal or diffuse spinal osteolysis may result in significant morbidity by causing painful progressive vertebral compression fractures (VCFs) and deformities. Advances in the systemic treatment of myeloma have achieved high response rates and prolonged the survival significantly. Early diagnosis and management of skeletal events contribute to improving the prognosis and quality of life of MM patients. The management of patients with significant pain due to VCFs in the acute phase is not standardised. While some patients are successfully treated conservatively, and pain relief is achieved within a few weeks, a large percentage has disabling pain and morbidity and hence they are considered for surgical intervention. Balloon kyphoplasty and percutaneous vertebroplasty are minimally invasive procedures which have been shown to relieve pain and restore function. Despite increasing positive evidence for the use of these procedures, the indications, timing, efficacy, safety and their role in the treatment algorithm of myeloma spinal disease are yet to be elucidated. This paper reports an update of the consensus statement from the International Myeloma Working Group on the role of cement augmentation in myeloma patients with VCFs.

Wnt signaling in multiple myeloma: a central player in disease with therapeutic potential

Multiple myeloma is the second most frequent hematological malignancy in the western world and remains incurable, predominantly due to acquired drug resistance and disease relapse. The highly conserved Wnt signal transduction pathway, which plays a key role in regulating cellular processes of proliferation, differentiation, migration, and stem cell self-renewal, is associated with multiple aspects of disease. Bone homeostasis is severely disturbed by Wnt antagonists that are secreted by the malignant plasma cells in the bone marrow. In the vast majority of patients, this results in osteolytic bone disease, which is associated with bone pain and pathological fractures and was reported to facilitate disease progression. More recently, cumulative evidence also indicates the importance of intrinsic Wnt signaling in the survival of multiple myeloma cells. However, Wnt pathway-activating gene mutations could not be identified. The search for factors or processes responsible for Wnt pathway activation currently focuses on aberrant ligand levels in the bone marrow microenvironment, increased expression of Wnt transcriptional co-factors and associated micro-RNAs, and disturbed epigenetics and post-translational modification processes. Furthermore, Wnt pathway activation is associated with acquired cell adhesion-mediated resistance of multiple myeloma cells to conventional drug therapies, including doxorubicin and lenalidomide. In this review, we present an overview of the relevance of Wnt signaling in multiple myeloma and highlight the Wnt pathway as a potential therapeutic target for this disease.

Fracture risk prediction using FRAX in patients following hematopoietic stem cell transplantation

We aimed to study the utility of the FRAX tool in predicting fractures in patient's receiving a hematopoietic stem cell transplantation (HSCT). Our results indicate that the FRAX tool has modest fracture predictive ability in patients greater than 50 years of age at the time of HSCT.

PURPOSE

Identifying patients at high risk of osteoporotic fractures following HSCT is challenging. We aimed to evaluate the utility of the FRAX tool at the time of HSCT in predicting fractures following transplant.

METHODS

We conducted a retrospective chart review of adults (> 18 years) who underwent HSCT at MD Anderson Cancer Center from January 1, 2001, to December 31, 2010, and were followed until December 31, 2013, to identify osteoporotic fractures. Multivariate Cox regression models were built using FRAX score thresholds of low risk < 10%, medium risk 10 to 20%, and high risk > 20% probability of osteoporotic fracture.

RESULTS

We identified 5170 patients who had undergone HSCT, 10% of whom developed an osteoporotic fracture during a median follow-up of 3.2 years. In patients > 65 years of age, those with medium risk (hazard ratio (HR) 2.38, 95% confidence interval (CI) 1.27-4.47) and high risk (HR 3.41, 95% CI 1.73-6.75) had a greater probability of developing an osteoporotic fracture compared to those at low risk. Similar trends were seen in patients 50 to 65 years of age.

CONCLUSIONS

In patients greater than 50 years, the FRAX tool has modest predictive ability and could be used to aid in preventive treatment decision-making at the time of transplant.

Evaluation of the Relevance of Surgery in Patients with Multiple Myeloma Harboring Symptomatic Spinal Involvement: A Retrospective Case Series

BACKGROUND

Multiple myeloma spinal involvement can lead to bone fractures and neurologic impairment that can severely alter quality of life. The role of surgery is controversial, given its high morbidity, and the lack of evidence. We hereby aim to evaluate efficacy and safety of surgery in the management of symptomatic spinal lesions in patients with multiple myeloma.

METHODS

We included all patients operated on for a myeloma-related spinal lesion in our institution between 2007 and 2015. Demographic, clinical, and surgical data were collected as well as hematologic profiles. We retrospectively assessed the surgical success of the procedures, if at 3 months the patient fulfilled the following 4 criteria: pain relief, ability to walk, spinal stability, and no relevant morbidity.

RESULTS

Thirty-six men and 19 women, with a median age of 62 years, were included. Seventeen patients underwent an emergency intervention, whereas 38 patients underwent elective surgery. At 3 months, 88.2% and 96.1%, respectively, of patients experienced pain relief and were able to walk. Spinal stability was considered satisfactory for 94.1% of patients. We reported 8 major complications in 8 patients. Altogether, 34 patients (61.8%) fulfilled all criteria for surgical success. An International Staging System score of 1 and the absence of previous chemotherapy were significantly associated with surgical success.

CONCLUSIONS

Management of myeloma-related spine lesions requires a multidisciplinary approach. Surgery rapidly provides both decompression and stabilization. Using a strict patient-specific evaluation, we reported rewarding functional results, with acceptable morbidity. Surgery for multiple myeloma vertebral lesions seems to be a valuable option for carefully selected patients.

Automated Whole-Body Bone Lesion Detection for Multiple Myeloma on 68Ga-Pentixafor PET/CT Imaging Using Deep Learning Methods

The identification of bone lesions is crucial in the diagnostic assessment of multiple myeloma (MM). 68Ga-Pentixafor PET/CT can capture the abnormal molecular expression of CXCR-4 in addition to anatomical changes. However, whole-body detection of dozens of lesions on hybrid imaging is tedious and error prone. It is even more difficult to identify lesions with a large heterogeneity. This study employed deep learning methods to automatically combine characteristics of PET and CT for whole-body MM bone lesion detection in a 3D manner. Two convolutional neural networks (CNNs), V-Net and W-Net, were adopted to segment and detect the lesions. The feasibility of deep learning for lesion detection on 68Ga-Pentixafor PET/CT was first verified on digital phantoms generated using realistic PET simulation methods. Then the proposed methods were evaluated on real 68Ga-Pentixafor PET/CT scans of MM patients. The preliminary results showed that deep learning method can leverage multimodal information for spatial feature representation, and W-Net obtained the best result for segmentation and lesion detection. It also outperformed traditional machine learning methods such as random forest classifier (RF), k-Nearest Neighbors (k-NN), and support vector machine (SVM). The proof-of-concept study encourages further development of deep learning approach for MM lesion detection in population study.

Panoramic and skull imaging may aid in the identification of multiple myeloma lesions

BACKGROUND

The purpose of this study was to investigate the presence of punched-out lesions in craniofacial bones using three different radiographic protocols in a large cohort of patients.

MATERIAL AND METHODS

One hundred fifty-five MM patients were evaluated using panoramic and skull (frontal and lateral) radiographs, which were performed in all patients at the time of MM diagnosis. The diagnostic potential for detecting punched-out lesions was compared among the radiographic techniques.

RESULTS

MM punched-out lesions were identified in 135 (87%) panoramic radiographs, 141 (91%) frontal and 144 (93%) lateral skull radiographs. Punched out-lesions were synchronously present in skull and jawbones in 129 (83.23 %) cases. The lesions were detected exclusively in skull in 18 (11.61%) cases and exclusively in jawbones in 6 (3.87%) cases. Punched out-lesion mainly affected the skull and the jawbones in a synchronous way (p<0.001) rather than separately.

CONCLUSIONS

All investigated radiographic techniques (panoramic, frontal and lateral skull approaches) demonstrated high detection rates for MM punched-out lesions in craniofacial bones. Panoramic radiography may aid to the radiographic protocols to identify multiple myeloma bone lesions.

Combination with third-generation bisphosphonate (YM529) and interferon-alpha can inhibit the progression of established bone renal cell carcinoma

The aim of this study was to investigate whether the third-generation nitrogen-containing bisphosphonate (YM529) can inhibit the progression of established bone renal cell carcinoma (RCC) and to elucidate its mechanism. Antiproliferative effect and apoptosis induction of RCC cells and mouse osteoclasts by YM529 and/or interferon-alpha (IFN-α) were evaluated in vitro using cell counting and in vivo using soft X-ray, the TUNEL method and tartrate-resistant acid phosphatase stain. For the in vivo study, male athymic BALB/cA Jc1-nu nude mice bearing human RCC cell line RBM1-IT4 cells were treated with YM529 and/or IFN-α. The biological activity of osteoclasts was evaluated using the pit formation assay. The antiangiogenetic effect by YM529 and/or IFN-α was analyzed using micro-vessel density and in situ mRNA hybridization. Osteoclast number in bone tumors was decreased in YM529-treated mouse. YM529 also inhibited osteoclast activity and proliferation in vitro, whereas basic fibroblast growth factor expressions and micro-vessel density within tumors were inhibited by IFN-α. Neither YM529 nor IFN-α alone significantly inhibited the growth of established bone metastatic tumors. Combined treatment with YM529 and IFN-α may be beneficial in patients with human RCC bone metastasis. Their effects are mediated by osteoclast recruitment inhibition and inactivation by YM529 and antiangiogenesis by IFN-α.

SDF-1 inhibition targets the bone marrow niche for cancer therapy

Bone marrow (BM) metastasis remains one of the main causes of death associated with solid tumors as well as multiple myeloma (MM). Targeting the BM niche to prevent or modulate metastasis has not been successful to date. Here, we show that stromal cell-derived factor-1 (SDF-1/CXCL12) is highly expressed in active MM, as well as in BM sites of tumor metastasis and report on the discovery of the high-affinity anti-SDF-1 PEGylated mirror-image l-oligonucleotide (olaptesed-pegol). In vivo confocal imaging showed that SDF-1 levels are increased within MM cell-colonized BM areas. Using in vivo murine and xenograft mouse models, we document that in vivo SDF-1 neutralization within BM niches leads to a microenvironment that is less receptive for MM cells and reduces MM cell homing and growth, thereby inhibiting MM disease progression. Targeting of SDF-1 represents a valid strategy for preventing or disrupting colonization of the BM by MM cells.

Sensitivity of whole-body CT and MRI versus projection radiography in the detection of osteolyses in patients with monoclonal plasma cell disease

PURPOSE

To compare sensitivity of whole-body Computed Tomography (wb-CT) and whole-body Magnetic Resonance Imaging (wb-MRI) with Projection Radiography (PR) regarding each method's ability to detect osteolyses in patients with monoclonal plasma cell disease.

PATIENTS AND METHODS

The bone status of 171 patients was evaluated. All patients presented with multiple myeloma (MM) of all stages, monoclonal gammopathy of unknown significance (MGUS) or solitary plasmacytoma. Two groups were formed. Group A consisted of 52 patients (26 females, 26 males) with an average age of 62 years (range, 45-89 years) who received, both, PR and wb-CT as part of their diagnostic work-up. Group B comprised 119 patients (58 females, 61 males) averaging 57 years of age (range, 20-80 years) who received, both, PR and wb-MRI. Two experienced radiologists were blinded regarding the disease status and assessed the number and location of osteolyses in consensus. A distinction was made between axial and extra-axial lesions.

RESULTS

In group A, wb-CT revealed osteolyses in 12 patients (23%) that were not detected in PR. CT was superior in detecting lesions in patients with osteopenia and osteoporosis. Compared with PR, wb-CT was significantly more sensitive in detecting osteolyses than PR (p<0.001). This was particularly true for axial lesions. Additionally, CT revealed clinically relevant incidental findings in 33 patients (63%). In group B, wb-MRI revealed lesions in 19 patients (16%) that were not detected in PR. All lesions detected by PR were also detected by wb-MRI and wb-CT. Wb-MRI and wb-CT are each superior to PR in detecting axial lesions.

CONCLUSION

Wb-CT can detect 23% more focal lesions than PR, especially in the axial skeleton. Therefore, this imaging method should be preferred over PR in the diagnostic work-up and staging of patients with monoclonal plasma cell disease.

PTHrP produced by myeloma plasma cells regulates their survival and pro-osteoclast activity for bone disease progression

To promote their survival and progression in the skeleton, osteotropic malignancies of breast, lung, and prostate produce parathyroid hormone-related protein (PTHrP), which induces hypercalcemia. PTHrP serum elevations have also been described in multiple myeloma (MM), although their role is not well defined. When we investigated MM cells from patients and cell lines, we found that PTHrP and its receptor (PTH-R1) are highly expressed, and that PTHrP is secreted both as a full-length molecule and as small subunits. Among these subunits, the mid-region, including the nuclear localization sequence (NLS), exerted a proliferative effect because it was accumulated in nuclei of MM cells surviving in starvation conditions. This was confirmed by increased transcription of several genes enrolled in proliferation and apoptosis control. PTHrP was also found to stimulate PTH-R1 in MM cells. PTH-R1's selective activation by the full-length PTHrP molecule or the NH2 -terminal fragment resulted in a significant increase of intracellular Ca(2+) influx, cyclic adenosine monophosphate (cAMP) content, and expression of receptor activator of NF-κB ligand (RANKL) and monocyte chemoattractant protein-1 (MCP-1). Our data definitely clarify the role of PTHrP in MM. The PTHrP peptide is functionally secreted by malignant plasma cells and contributes to MM tumor biology and progression, both by intracrine maintenance of cell proliferation in stress conditions and by autocrine or paracrine stimulation of PTH-R1, which in turn reinforces the production of osteoclastogenic factors. © 2014 American Society for Bone and Mineral Research.

Treatment of spinal epidural compression due to hematological malignancies: a single institution's retrospective experience

PURPOSE

To analyze the neurological and mechanical outcomes in 44 consecutive patients treated for a hematological malignancy with epidural localization to assess the place of surgery in the treatment of this pathology.

METHODS

Clinical records, CT and MRI scans of 44 patients with epidural localizations of multiple myeloma or lymphoma treated between 1990 and 2005 were analyzed retrospectively. Neurological status, epiduritis and osteolysis volumes, vertebral collapse, and spinal canal compromise were assessed. The neurological outcome was graded according to Frankel and the mechanical outcome was evaluated on the rate of vertebral collapse.

RESULTS

Surgery was performed in 11 patients (25 %) for neurological (n = 9) or mechanical (n = 2) reasons. In five cases, a concomitant biopsy was performed because the etiology of the epiduritis was unknown. Fifteen patients (34.1 %) presented with a neurological deficit secondary to an acute vertebral collapse (n = 4), an epiduritis (n = 7), or both (n = 4). Whatever the treatment (surgical or not), a complete recovery (Frankel E) occurred in 14/15 (93.3 %) after a mean delay of 12 weeks (range 2-24 weeks). During the follow-up, seven collapses occurred. We estimated that a threshold of 30 % of osteolysis was associated with a significant risk of vertebral collapse (P = 0.005).

CONCLUSIONS

Hematological malignancies with epidural localization must be treated first medically, even in patients with neurological symptoms. Surgery should be considered only in the cases of acute vertebral collapse, medical treatment failure, or to prevent acute collapse in patients with vertebral osteolysis of more than 30 %.

Stable changes in mesenchymal stromal cells from multiple myeloma patients revealed through their responses to Toll-like receptor ligands and epidermal growth factor

In human multiple myeloma (MM), the tumor cells exhibit strict dependence on bone marrow (BM) stromal elements. It has been suggested that, in turn, MM cells modify multipotent stromal cells (MSCs), diverting them to support the myeloma. We investigated MM-derived MSCs by comparing their toll-like receptor (TLR) responses to those of MSCs derived from healthy controls. We now report that MM-derived MSCs manifested intact proliferation responses and IL-6 secretion and their adipose and osteogenic differentiation responses to TLR ligands were also similar to those of healthy controls, ranging from augmentation to inhibition. However, MM-derived MSCs were found to be defective in IL-8 secretion and ERK1/2 phosphorylation following TLR-2 activation. Moreover, MM-derived MSCs failed to respond to EGF by elevation of ERK1/2 phosphorylation. The persistence of these changes in extensively cultured MM-derived MSCs, suggests that these cells are stably, if not irreversibly modified.

Myeloma as a model for the process of metastasis: implications for therapy

Multiple myeloma (MM) is a plasma cell dyscrasia characterized by the presence of multiple myelomatous "omas" throughout the skeleton, indicating that there is continuous trafficking of tumor cells to multiple areas in the bone marrow niches. MM may therefore represent one of the best models to study cell trafficking or cell metastasis. The process of cell metastasis is described as a multistep process, the invasion-metastasis cascade. This involves cell invasion, intravasation into nearby blood vessels, passage into the circulation, followed by homing into predetermined distant tissues, the formation of new foci of micrometastases, and finally the growth of micrometastasis into macroscopic tumors. This review discusses the significant advances that have been discovered in the complex process of invasion-metastasis in epithelial carcinomas and cell trafficking in hematopoietic stem cells and how this process relates to progression in MM. This progression is mediated by clonal intrinsic factors that mediate tumor invasiveness as well as factors present in the tumor microenvironment that are permissive to oncogenic proliferation. Therapeutic agents that target the different steps of cell dissemination and progression are discussed. Despite the significant advances in the treatment of MM, better therapeutic agents that target this metastatic cascade are urgently needed.

18F-FDG PET/CT for detection and localization of residual or recurrent disease in patients with multiple myeloma after stem cell transplantation

PURPOSE

The aim of the study was to determine the diagnostic performance of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT for the detection and localization of residual or recurrent disease in patients with multiple myeloma (MM) after stem cell transplantation.

METHODS

A total of 197 whole-body (18)F-FDG PET/CT scans were performed in 99 patients with MM at different time points in the course of disease after autologous or allogeneic stem cell transplantation. Post-transplant PET/CT scans and clinical remission status as determined by the clinical gold standard (Uniform Response Criteria) were analysed and compared.

RESULTS

A total of 576 focal osseous and extramedullary lesions were detected in 79 scans. Additional diffuse bone marrow involvement was detected in 17 patients. (18)F-FDG PET/CT had a sensitivity of 54.6%, a specificity of 82.1%, a positive predictive value of 82.3%, a negative predictive value of 54.2% and an overall accuracy of 65.5%. The sensitivity of (18)F-FDG PET/CT was shown to depend on the disease category according to the Uniform Response Criteria for myeloma.

CONCLUSION

In patients with MM in the post-transplant setting, (18)F-FDG PET/CT may (1) contribute to the detection and localization of disease, (2) provide information about the extent of distinct myeloma manifestations and the total disease burden and (3) add information about the metabolic activity of disease, but (4) has substantially lower sensitivity for this purpose compared to the pretreatment setting.

Novel approaches in the management of myeloma-related skeletal complications

Patients with multiple myeloma (MM) experience pathologic fractures, bone pain, hypercalcemia, neurologic symptoms, and renal insufficiency with substantial morbidity and mortality. Bisphosphonates have been used successfully for the management of MM-related bone disease. Increased incidence of osteonecrosis of the jaw has been observed in patients with cancer receiving bisphosphonate therapy. Recent advances in the pathobiology of MM-related bone disease and other cancer-related bone metastases have led to the identification of novel therapeutic targets, such as receptor activator of nuclear factor-kappaB (RANK); its ligand (RANKL); and a decoy receptor, osteoprotegerin, for the development of potential targeted agents. Initials studies have demonstrated that targeting RANK/ RANKL signaling with the fully human monoclonal antibody denosumab prevented skeletal complications in patients with MM and other cancers with bone metastases. Ongoing studies evaluating the clinical utility of denosumab in cancer- related bone destruction have been discussed. In addition, several potential targets, such as macrophage inflammatory protein-1alpha, chemokine receptors 1 and 5, interleukin-3, and Wnt signaling, are b riefly described.

Osteoimmunology at the nexus of arthritis, osteoporosis, cancer, and infection

Over the past decade and a half, the biomedical community has uncovered a previously unappreciated reciprocal relationship between cells of the immune and skeletal systems. Work in this field, which has been termed "osteoimmunology," has resulted in the development of clinical therapeutics for seemingly disparate diseases linked by the common themes of inflammation and bone remodeling. Here, the important concepts and discoveries in osteoimmunology are discussed in the context of the diseases bridging these two organ systems, including arthritis, osteoporosis, cancer, and infection, and the targeted treatments used by clinicians to combat them.

Macrophage inflammatory protein-1α induces osteoclast formation by activation of the MEK/ERK/c-Fos pathway and inhibition of the p38MAPK/IRF-3/IFN-β pathway

Multiple myeloma (MM) is a bone disease that affects many individuals. It was recently reported that macrophage inflammatory protein (MIP)-1α is constitutively secreted by MM cells. MIP-1α causes bone destruction through the formation of osteoclasts (OCs). However, the molecular mechanism underlying MIP-1α-induced OC formation is not well understood. In the present study, we attempted to clarify the mechanism whereby MIP-1α induces OC formation in a mouse macrophage-like cell line comprising C7 cells. We found that MIP-1α augmented OC formation in a concentration-dependent manner; moreover, it inhibited IFN-β and ISGF3γ mRNA expression, and IFN-β secretion. MIP-1α increased the expressions of phosphorylated ERK1/2 and c-Fos and decreased those of phosphorylated p38MAPK and IRF-3. We found that the MEK1/2 inhibitor U0126 inhibited OC formation by suppressing the MEK/ERK/c-Fos pathway. SB203580 induced OC formation by upregulating c-fos mRNA expression, and SB203580 was found to inhibit IFN-β and IRF-3 mRNA expressions. The results indicate that MIP-1α induces OC formation by activating and inhibiting the MEK/ERK/c-Fos and p38MAPK/IRF-3 pathways, respectively, and suppressing IFN-β expression. These findings may be useful in the development of an OC inhibitor that targets intracellular signaling factors.

Osteoclast-gene expression profiling reveals osteoclast-derived CCR2 chemokines promoting myeloma cell migration

Multiple myeloma is characterized by the clonal expansion of malignant plasma cells (multiple myeloma cells [MMCs]), in the bone marrow. Osteolytic bone lesions are detected in 80% of patients because of increased osteoclastic bone resorption and reduced osteoblastic bone formation. MMCs are found closely associated with sites of increased bone resorption. Osteoclasts strongly support MMC survival in vitro. To further elucidate the mechanisms involved in osteoclast/MMC interaction, we have identified 552 genes overexpressed in osteoclasts compared with other bone marrow cell subpopulations. Osteoclasts express specifically genes coding for 4 CCR2-targeting chemokines and genes coding for MMC growth factors. An anti-CCR2 monoclonal antibody blocked osteoclast chemoattractant activity for MMC, and CCR2 chemokines are also MMC growth factors, promoting mitogen-activated protein kinase activation in MMC. An anti-insulin growth factor-1 receptor monoclonal antibody completely blocked the osteoclast-induced survival of MMC suppressing both osteoclast and MMC survival. Specific a proliferation-inducing ligand or IL-6 inhibitors partially blocked osteoclast-induced MMC survival. These data may explain why newly diagnosed patients whose MMC express high levels of CCR2 present numerous bone lesions. This study displays additional mechanisms involved in osteoclast/MMC interaction and suggests using CCR2 and/or insulin growth factor-1 targeting strategies to block this interaction and prevent drug resistance.

Management of painful spinal lesions caused by multiple myeloma using percutaneous acrylic cement injection

BACKGROUND AND PURPOSE

Spinal lesions with marked destruction are common site of morbidity in patients with multiple myeloma causing serious clinical symptoms. The aim of the study was to evaluate the therapeutic benefit of percutaneous vertebroplasty (PVP) in treating vertebral body lesions in patients suffering from multiple myeloma.

MATERIALS AND METHODS

Twenty nine patients (55 vertebral bodies) were treated after complete diagnostic evaluation, preparation and obtaining informed consent. Needle position and acrylic material injection was performed under fluoroscopic guidance.

RESULTS

Average visual analogue score dropped from 7.8 before to 2.3 after the intervention. Soft tissue leak was present at 9 treated levels, small epidural cement collection at 5, venous leak at 4 and intradiscal leak at 3 levels without any clinically manifest complications. The effects of PVP were stable in all of the patients at 12 months follow-up. Subjective outcome scores collected through follow-up showed improvement of +1.45 in pain, + 1.15 in ambulation and + 1.23 in medication use. There were recurrence of back pain in 9 patients at non-treated levels due to the new lesions.

CONCLUSION

In our series, PVP of painful lesions caused by multiple myeloma provides immediate and long-term pain relief. The procedure is safe and, despite of the present leakage of cement, may be performed on outpatients basis.

Targeting the bone microenvironment in multiple myeloma

Multiple myeloma (MM) is a plasma cell malignancy characterized by the frequent development of osteolytic lesions, osteopenia, pathological fractures, and/or severe bone pain. In the past few years several potential factors involved in this process have been identified and, with the increased knowledge of the signaling pathways involved in the regulation of normal osteoblast and osteoclast function, have provided us with a better understanding of the contributions of the marrow microenvironment to MM bone disease. These studies have identified several potential novel targets for treating MM bone disease in addition to the current standard treatment of bisphosphonates. In this article, we discuss several potential targets for treating MM bone disease as well as novel therapies that are in clinical trials for these patients.

Breaking tolerance in a mouse model of multiple myeloma by chemoimmunotherapy

A unique mouse model of multiple myeloma (MM), namely 5T2MM-bearing mouse, was useful for elucidating the pathophysiological mechanisms underlying the disease. Increased accumulation of suppressive CD4(+)CD25(High)Foxp3(+) regulatory T cells (Tregs) was observed in the thymus and lymphoid peripheral organs during disease progression. Adoptive transfer of Tregs, but not other thymocytes, from 5T2MM-bearing mice led to increased progression of disease manifestations in young syngeneic mice. Depletion of Tregs, a proposed strategy in cancer immunotherapy, was tested using cyclophosphamide (CYC), an alkylating agent with selective cytotoxicity. Both low- and high-dose CYC, administered to sick mice with hind limb paralysis, caused the paralysis to disappear, the plasma tumor cells in the bone marrow (BM) cavity to be replaced by normal cell populations, and the survival of the mice to be significantly prolonged. Low-dose CYC, which selectively depletes Tregs, decreased MM incidence, in contrast to high-dose CYC, which was generally cytotoxic, and did not reduce MM incidence. In contrast, low-dose CYC induced Tregs to become susceptible to apoptosis by downregulating Bcl-xL and CTLA-4 in these cells, and by decreasing the production of IL-2 by effector CD4 cells. This treatment consequently triggered the recovery of IFN-gamma-producing natural killer T cells and the maturation of dendritic cells. Transient gradual depletion of Tregs in low-dose CYC-treated 5T2MM mice was maintained beyond 45 days. Thus, less frequent injections of low-dose CYC enabled us to recruit compatible immune-derived cells that would reduce tumor load and delay or prevent tumor recurrence, hence breaking immune tolerance toward MM tumor cells.

The prognostic value of F-18 fluorodeoxyglucose bone marrow uptake in patients with recent diagnosis of multiple myeloma: a comparative study with Tc-99m sestamibi

PURPOSE

We assessed the prognostic value of F-18 fluorodeoxyglucose (FDG) uptake in the bone marrow of patients with multiple myeloma (MM) in comparison with Tc-99m methoxy-isobutyl-isonitrile (MIBI).

METHODS

The extent and intensity of FDG and MIBI uptake in the bone marrow of 18 patients with a recent diagnosis of MM were assessed by visual score and by calculating the mean SUV (mSUV) for FDG and the femora/thigh ratio (TG/BKG, [Target/Background ratio]) for MIBI images. These parameters were correlated with clinical indexes of disease using hemoglobin and beta-2-microglobulin levels and plasma cell infiltrate (PCI) percentage. The mean values of the visual score, mSUV, and TG/BKG levels were compared in patients deceased after a relatively short follow-up (n = 9; group A) and in patients with a longer survival or were alive at the end of the study (n = 9; group B).

RESULTS

Significant correlations of mSUV and TG/BKG values with PCI percentages and beta-2-microglobulin were found (P < 0.05). The extent of FDG and MIBI bone marrow uptake was greater in patients of group A (P < 0.01). Higher values of mSUV (P < 0.01) and TG/BKG (P < 0.05) were also observed in patients of group A. These results were consistent with the differences (not statistically significant) in hemoglobin, albumin, beta-2-microglobulin levels, and PCI percentages observed in the 2 groups.

CONCLUSION

Our study demonstrates that an increase of FDG bone marrow uptake may predict a more aggressive disease, as much as MIBI uptake. Therefore, an additional analysis of FDG bone marrow images should be performed in patients undergoing PET studies during the initial staging of MM.

Current developments in salivary diagnostics

Salivary diagnostics is an emerging field that has progressed through several important developments in the past decade, including the publication of the human salivary proteome and the infusion of federal funds to integrate nanotechnologies and microfluidic engineering concepts into developing compact point-of-care devices for rapid analysis of this secretion. In this article, we discuss some of these developments and their relevance to the prognosis, diagnosis and management of periodontitis, as an oral target, and cardiovascular disease, as a systemic example for the potential of these biodiagnostics. Our findings suggest that several biomarkers are associated with distinct biological stages of these diseases and demonstrate promise as practical biomarkers in identifying and managing periodontal disease, and acute myocardial infarction. The majority of these studies have progressed through biomarker discovery, with the identified molecules requiring more robust clinical studies to enable substantive validation for disease diagnosis. It is predicted that with continued advances in this field the use of a combination of biomarkers in multiplex panels is likely to yield accurate screening tools for these diagnoses in the near future.

RANKL inhibition: clinical implications for the management of patients with multiple myeloma and solid tumors with bone metastases

BACKGROUND

Receptor activator of NF-kappaB ligand (RANKL) binds to RANK on the surface of osteoclast precursors and enhances their differentiation, survival and fusion, activates mature osteoclasts and inhibits their apoptosis. Osteoprotegerin (OPG) is the decoy receptor of RANKL. Disruption of the RANK/RANKL/OPG axis is implicated in bone metastases.

OBJECTIVE/METHODS

A review of the role of RANKL signaling in bone development and the rationale for targeting RANKL in treatment of bone metastases and myeloma bone disease.

RESULTS/CONCLUSIONS

In preclinical models of solid tumors and myeloma, RANKL inhibition reduced osteoclast numbers and subsequent bone resorption, prevented development of osteolytic lesions and decreased tumor burden. Preliminary clinical studies with denosumab, an anti-RANKL fully human monoclonal antibody, in patients with solid tumors with bone metastases and myeloma showed that targeting RANKL reduces osteoclastogenesis, bone resorption markers and skeletal-related events, supporting further study of this molecule and others with anti-RANKL activity.

[Pelvic and spinal MR follow-up of multiple myeloma patients after high-dose chemotherapy and autologous peripheral blood stem cell transplant]

PURPOSE

To evaluate the changes of bone marrow lesions on pelvic and spinal MR in patients with multiple myeloma after high-dose chemotherapy and autologous peripheral blood stem cell transplant.

PATIENTS AND METHODS

Pelvic and spinal MR examinations were obtained at presentation (myeloma diagnosis) and 1 year after transplant in 20 patients that were part of a group of 39 patients enrolled in a prospective study. The type of marrow replacement (classified in stages with stage 0: normal; stage 1: salt and pepper; stage 2: focal infiltration; stage 3: diffuse infiltration), the number and size of marrow lesions and the number of vertebral compression fractures were recorded. We have compared the findings prior to and following transplant, with correlation to the response to treatment and the use of biphosphonates.

RESULTS

The type of marrow replacement was improved following transplant in 65% of patients (not statistically significant). The number and size of nodules > 20 mm showed significant reduction (p = 0.0224 and p = 0.0237 respectively). Lesions on MR improved in 50% of patients with good response and 75% of patients with poor response to treatment. Patients receiving biphosphonates showed more vertebral compression fractures.

CONCLUSION

The evolution of marrow replacing lesions on MR is discordant compared to the biological and clinical response to treatment. Pelvic and spinal MR evaluation at the time of diagnosis does not appear to be a good predictive factor of response to treatment. Biphosphonates do not appear to prevent new vertebral compression fractures. Pelvic and spinal MR provides interesting data in the follow-up of patients with myeloma following autologous transplant, especially in the local evolution of marrow replacing lesions, but our results do not justify its use in routine clinical practice.

A novel model of bone-metastatic prostate cancer in immunocompetent mice

BACKGROUND

Bone metastasis is a frequent and catastrophic consequence of prostate cancer for which only palliative treatment is available. Animal models of bone metastatic prostate cancer are necessary for understanding disease mechanisms but few models exist.

METHODS

We have used the murine prostate carcinoma cell line RM1 to generate a bone metastatic model of prostate cancer. Repeated intracardiac injection of RM1 cells followed by isolation of cells from bone tumors has yielded a cell line with strong bone-metastatic potential, RM1 bone metastatic (BM).

RESULTS

This cell line metastasizes to multiple bony sites in over 95% of injected C57BL/6 mice and is far less tropic to soft tissues. Bone tumors produced by the RM1(BM) cell line show no preference for particular skeletal sites as most bones are affected. Histology, and micro-computed tomography show that RM1(BM) cells form osteolytic tumors, but with evidence of osteoblastic changes. In vitro the RM1 cells express E-cadherin but not vimentin, do not form colonies in soft agar, are non-invasive but are more motile than the parent cell line.

CONCLUSIONS

This model provides a novel means for identifying cellular and molecular mechanisms that contribute to bone metastasis and allow for preclinical testing of therapies to prevent and treat tumor metastasis to bone. Finally as the syngeneic tumor cells are injected into immunocompetent mice, this model will provide a means to study interactions between the immune system, tumors and bone, and therapies that target such interactions.

Diffuse Large B-cell Lymphoma Presenting with Hypercalcemia and Multiple Osteolysis

Osteolysis and hypercalcemia are observed in 5-15%, and 10%, respectively, of malignant lymphoma patients during their clinical course. However, both osteolysis and hypercalcemia are uncommon at onset of the disease. We encountered a 24-year-old male non-Hodgkin's lymphoma patient who had multiple osteolytic lesion from the onset of the disease and repeated episodes of hypercalcemia during the clinical course. The patient died with refractory disease. We studied the expression of chemokines which might affect bone resorption using the reverse transcriptase-polymerase chain reaction (RT-PCR) method. Increased expressions of MIP-1alpha, MIP-1beta and RANKL, which are osteoclast-activating factors, were observed in the RNA derived from the patient's lymphoma cells. The secretion of osteoclast-activating factors such as MIP-1alpha by the tumor cells (and/or bone marrow stromal cells) might be involved in the etiology of osteolysis and hypercalcemia in some malignant lymphoma cases.

International myeloma working group consensus statement and guidelines regarding the current role of imaging techniques in the diagnosis and monitoring of multiple Myeloma

Several imaging technologies are used for the diagnosis and management of patients with multiple myeloma (MM). Conventional radiography, computed tomography (CT), magnetic resonance imaging (MRI) and nuclear medicine imaging are all used in an attempt to better clarify the extent of bone disease and soft tissue disease in MM. This review summarizes all available data in the literature and provides recommendations for the use of each of the technologies. Conventional radiography still remains the 'gold standard' of the staging procedure of newly diagnosed and relapsed myeloma patients. MRI gives information complementary to skeletal survey and is recommended in MM patients with normal conventional radiography and in all patients with an apparently solitary plasmacytoma of bone. Urgent MRI or CT (if MRI is not available) is the diagnostic procedure of choice to assess suspected cord compression. Bone scintigraphy has no place in the routine staging of myeloma, whereas sequential dual-energy X-ray absorptiometry scans are not recommended. Positron emission tomography/CT or MIBI imaging are also not recommended for routine use in the management of myeloma patients, although both techniques may be useful in selected cases that warrant clarification of previous imaging findings, but such an approach should ideally be made within the context of a clinical trial.

Increased regulatory versus effector T cell development is associated with thymus atrophy in mouse models of multiple myeloma

CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) play a central role in cancer tolerance. However, mechanisms leading to their accumulation in cancer remain unknown. Although the thymus is the main site of Treg development, thymic contribution to Treg expansion in cancer has not been directly examined. Herein, we used two murine models of multiple myeloma (MM), 5T2 MM and 5T33 MM, to examine Treg accumulation in peripheral lymphoid organs, including spleen, lymph nodes, bone marrow, and blood, and to explore thymic Treg development during malignancy. We found that peripheral ratios of suppressive-functional Tregs increased in both models of MM-inflicted mice. We found that thymic ratios of Treg development in MM increased, in strong association with thymus atrophy and altered developmental processes in the thymus. The CD4(+)CD8(+) double-positive population, normally the largest thymocyte subset, is significantly decreased, whereas the CD4(-)CD8(-) double-negative population is increased. Administration of thymocytes from MM-inflicted mice compared with control thymocytes resulted in increased progression of the disease, and this effect was shown to be mediated by Tregs in the thymus of MM-inflicted mice. Our data suggest that increased ratios of Treg development in the thymus may contribute to disease progression in MM-inflicted mice.

Lenalidomide inhibits osteoclastogenesis, survival factors and bone-remodeling markers in multiple myeloma

Osteolytic bone disease in multiple myeloma (MM) is caused by enhanced osteoclast (OCL) activation and inhibition of osteoblast function. Lenalidomide and bortezomib have shown promising response rates in relapsed and newly diagnosed MM, and bortezomib has recently been reported to inhibit OCLs. We here investigated the effect of lenalidomide on OCL formation and osteoclastogenesis in comparison with bortezomib. Both drugs decreased alpha V beta 3-integrin, tartrate-resistant acid phosphatase-positive cells and bone resorption on dentin disks. In addition, both agents decreased receptor activator of nuclear factor-kappaB ligand (RANKL) secretion of bone marrow stromal cells (BMSCs) derived from MM patients. We identified PU.1 and pERK as major targets of lenalidomide, and nuclear factor of activated T cells of bortezomib, resulting in inhibition of osteoclastogenesis. Furthermore, downregulation of cathepsin K, essential for resorption of the bone collagen matrix, was observed. We demonstrated a significant decrease of growth and survival factors including macrophage inflammatory protein-alpha, B-cell activating factor and a proliferation-inducing ligand. Importantly, in serum from MM patients treated with lenalidomide, the essential bone-remodeling factor RANKL, as well as the RANKL/OPG ratio, were significantly reduced, whereas osteoprotegerin (OPG) was increased. We conclude that both agents specifically target key factors in osteoclastogenesis, and could directly affect the MM-OCL-BMSCs activation loop in osteolytic bone disease.

Bone marrow microenvironment and tumor progression

The bone marrow constitutes an unique microenvironment for cancer cells in three specific aspects. First, the bone marrow actively recruits circulating tumor cells where they find a sanctuary rich in growth factors and cytokines that promote their proliferation and survival. When in the bone marrow, tumor cells profoundly affect the homeostasis of the bone and the balance between osteogenesis and osteolysis. As a consequence, growth and survival factors normally sequestered into the bone matrix are released, further fueling cancer progression. Second, tumor cells actively recruit bone marrow-derived precursor cells into their own microenvironment. When in the tumors, these bone marrow-derived cells contribute to an inflammatory reaction and to the formation of the tumor vasculature. Third, bone marrow-derived cells can home in distant organs, where they form niches that attract circulating tumor cells. Our understanding of the contribution of the bone marrow microenvironment to cancer progression has therefore dramatically improved over the last few years. The importance of this new knowledge cannot be underestimated considering that the vast majority of cancer treatments such as cytotoxic and myeloablative chemotherapy, bone marrow transplantation and radiation therapy inflict a trauma to the bone marrow microenvironment. How such trauma affects the influence that the bone marrow microenvironment exerts on cancer is still poorly understood. In this article, the reciprocal relationship between the bone marrow microenvironment and tumor cells is reviewed, and its potential impact on cancer therapy is discussed.

Elevated tumor necrosis factor-alpha suppresses TAZ expression and impairs osteogenic potential of Flk-1+ mesenchymal stem cells in patients with multiple myeloma

One of the clinical features of multiple myeloma (MM) is the occurrence of skeletal events, which are characterized by increased bone resorption and decreased bone formation. In contrast to enhanced osteoclastogenesis, little is known about the mechanism of impaired bone formation in MM. Because TAZ, a Runx2/Cbfa1 transcriptional co-activator, has recently been shown to modulate mesenchymal stem cell (MSC) differentiation in favor of osteoblast differentiation, we investigated whether the regulation of TAZ expression played a role in the decreased bone formation of MM. We isolated and purified Flk-1(+)CD31(-)CD34(-) cells with MSC characters from bone marrow (BM) of myeloma patients and healthy donors. We found the osteogenic potential of the MSCs from myeloma patients decreased significantly, and TAZ expression of these cells was lower than that of healthy donors. Human myeloma cell lines (HMCLs) and CD138(+) myeloma cells (MCs) from myeloma patients inhibited osteogenesis of the MSCs from healthy volunteers, which were accompanied by a reduced TAZ expression and elevated TNF-alpha concentration in the supernatant of co-culture systems. The repressed osteogenesis and TAZ expression were both partially restored by neutralization of TNF-alpha. Thus, the decreased osteogenic potential of MSCs of myeloma patients was in part due to TNF-alpha suppressed TAZ expression.

The role of the bone marrow microenvironment in the pathophysiology of myeloma and its significance in the development of more effective therapies

Multiple myeloma (MM) is viewed as a prototypic disease state for the study of how neoplastic cells interact with their local bone marrow (BM) microenvironment. This interaction reflects not only the osteo-tropic clinical behavior of MM and the clinical impact of the lytic bone lesions caused by its tumor cells but also underlines the broadly accepted notion that nonneoplastic cells of the BM can attenuate the activity of cytotoxic chemotherapy and glucocorticoids. This article summarizes the recent progress in characterization, at the molecular and cellular levels, of how the BM milieu interacts with MM cells and modifies their biologic behavior.

PTHrP-independent hypercalcemia with increased proinflammatory cytokines and bone resorption in two children with CD19-negative precursor B acute lymphoblastic leukemia

Hypercalcemia in childhood acute lymphoblastic leukemia (ALL) is rare and occasionally associated with parathyroid hormone-related protein (PTHrP). However, the pathogenesis of PTHrP-independent hypercalcemia remains unclear. We report two children with precursor B ALL who had marked hypercalcemia (15.8 and 16.6 mg/dl, respectively) and disseminated osteolysis. Serum tumor necrosis factor-alpha (TNF-alpha) and IL-6 were markedly elevated, whereas 1,25(OH)(2) vitamin D(3), intact PTH and PTHrP were decreased or undetected. Analysis of urinary deoxypyridinoline (DPY) or bone biopsy of the osteolytic lesion showed an increased bone resorption, and administration of bisphosphonate improved the hypercalcemia. Patients had ALL with immunophenotype positive for CD10, CD34, and HLA-DR but negative for CD19 and obtained remission with chemotherapy. These findings suggest that increased osteoclastic bone resorption via stimulation with TNF-alpha and IL-6 may be mechanism causing PTHrP-independent hypercalcemia in some patients with precursor B ALL lacking CD19 expression.