Pathophysiology and management of bone disease in multiple myeloma

Multiple Myeloma Involving Left Hemicranium

Multiple myeloma (MM) is a malignant neoplasm of bone marrow affecting plasma cells. It is commonly seen as multiple punched-out lesions in the skull bone as a characteristic feature. Its presentation as hemicranial involvement with intracranial extension is rare. A 46-year-old male presented with left side scalp swelling, prominent over parietal region. X-ray showed multiple punched out lesions involving left hemicranium. CT and MRI brain showed intracranial extension of lesion without brain parenchyma invasion. He was treated with biopsy of lesion followed by chemotherapy.

Relationship between serum levels of vascular endothelial growth factor, hepatocyte growth factor and matrix metalloproteinase-9 with biochemical markers of bone disease in multiple myeloma

BACKGROUND

Multiple myeloma is characterized by accumulation of plasma cells in the bone marrow, with osteolysis and increased marrow angiogenesis. We studied molecules involved in angiogenesis (MMP-9, HGF, VEGF) in relation to disease stage, extent of bone destruction, and markers of bone turnover (Ntx and PICP).

METHODS

MMP-9, HGF, VEGF were measured in the serum of 42 newly diagnosed myeloma patients and 24 controls with commercial ELISA kits. Urinary levels of Ntx were measured by ELISA, and serum PICP with RIA. Extent of radiological bone disease was graded into low and high score. Stage was estimated according to the Durie-Salmon criteria.

RESULTS

HGF, VEGF and Ntx were higher in patients than controls (p<0.001). MMP-9 and PICP did not differ between patients and controls. HGF, VEGF, MMP-9 and Ntx increased significantly with disease stage (I to III, p<0.001) and PICP decreased significantly with advancing stage (p<0.05). There was a positive correlation between HGF and MMP-9 (r: 0.36, p<0.01), VEGF and MMP-9 (r: 0.38, p<0.01), Ntx and MMP-9 (r: 0.39, p<0.01) and an inverse correlation between PICP and MMP-9 (r: -0.66, p<0.0001).

CONCLUSIONS

Angiogenesis and bone destruction are closely interrelated in myeloma, and cytokine levels (MMP-9, VEGF and HGF) may be useful in monitoring progression.

Systemic levels of interleukin-6 and matrix metalloproteinase-9 in patients with multiple myeloma may be useful as prognostic indexes of bone disease

Multiple myeloma is characterized by accelerated production of the proteolytic enzyme matrix metalloproteinase (MMP)-9. We hypothesized that myeloma-produced MMP-9 may influence the rate of bone turnover in a paracrine manner. Thus, we examined the correlations of MMP-9 levels, disease severity, and bone turnover rate as evaluated by markers of bone formation and resorption.

Thirty-seven newly diagnosed multiple myeloma patients (nine of Durie-Salmon stage I, 12 of stage II and 16 of stage III) and 12 age-matched controls were studied. Serum MMP-9 levels were significantly higher at stage II compared to stage I (188.78±91.27 vs. 59.25±33.09 ng/mL, p<0.004). Additionally, free urine pyridinolines (F-Pyd), free urine deoxy-pyridinolines (F-Dpd) and urine N-telopeptide fragment (NTx) were elevated, their level correlating with disease stage (p<0.001, p<0.03, p<0.001, respectively), as were bone marrow infiltration and serum interleukin-6 (IL-6) levels (p<0.0001, p<0.01, respectively). MMP-9 levels were lower in patients compared with controls (p<0.001), whereas IL-6 and bone resorption marker levels were higher in patients than in controls (p<0.001 in all cases). Significant correlation was found between infiltration, MMP-9, free urine pyd, free urine dpd and NTx for each stage of the disease (p<0.03, p<0.003, p<0.002, p<0.003 and p<0.001, respectively). Levels of MMP-9 and of IL-6 in multiple myeloma correlate well with bone turnover rate and may be useful in disease evaluation.

Multiple myeloma: clinical review and diagnostic imaging

Multiple myeloma (MM) is a malignant clonal neoplasm of plasma cells of B-lymphocyte origin that commonly results in overproduction of large amounts of monoclonal immunoglobulins. Important advances in the therapeutic management of this disease in the past decade have resulted in higher rates of durable complete remission, prolonged event-free survival, and improved overall survival. Clearer understanding of the effects of abnormal plasma cells on bone has led to therapeutic approaches that help prevent vertebral body fractures. Current imaging technologies and, in particular, survey marrow studies with magnetic resonance (MR) imaging have improved detection of the extent and location of disease in MM patients. In newly diagnosed cases, MR surveys of the axial skeleton accurately demonstrate the extent of disease-diffuse or focal involvement-and the presence of associated compression fractures and cord compression. After treatment, MR images show the effects of treatment and the presence of residual disease. Multiple sites of focal bone lesions detected on MR studies allow a more appropriate choice of biopsy site than the usual random iliac marrow biopsy. Use of MR to determine biopsy sites and computed tomographic guidance for biopsy performance have increased the safety and accuracy of sampling. These biopsies have resulted in increased identification of cytogenetic abnormalities, particularly the presence of chromosome 13 deletion, which is a grave prognostic indicator in MM.

Wnt signaling in B-cell neoplasia

Wnts comprise a family of secreted proteins that interact with receptors consisting of a Frizzled (Fz) family member alone or complexed with LDL receptor-related proteins (LRP5/6). Wnt signaling plays a crucial role in both development and differentiation, and activation of a 'canonical' Wnt pathway resulting in beta-catenin stabilization is associated with several types of human cancers. To date, little is known about potential Wnt signaling in mature lymphocytes or lymphoid neoplasia. Herein, we have analysed Wnt signaling in mature B cells (lymphomas) and plasma cells (multiple myeloma). Both Fz and LRP5/6 mRNAs were expressed in myeloma lines, but LRP5/6 were not observed in lymphomas. In myelomas, a canonical Wnt signaling pathway was activated following treatment with Wnt-3a as assessed by accumulation of beta-catenin, but beta-catenin levels actually decreased in lymphoma cells. Wnt-3a treatment further led to striking morphological changes in myeloma cells accompanied by rearrangement of the actin cytoskeleton. Morphological changes were associated with a second Wnt pathway dependent on Rho activation. These results suggest that Wnt responsiveness is a stage-specific phenomenon in B-cell development and that the morphological changes associated with Wnt signaling may play a role in the motility and metastatic potential of myeloma cells.

Urinary N-telopeptide levels in multiple myeloma patients, correlation with Tc-99m-sestaMIBI scintigraphy and other biochemical markers of disease activity

Urinary cross-linked N-telopeptide of type I collagen (NTx) has been reported to be a sensitive and specific marker of bone resorption in multiple myeloma (MM). In this study, we measured the levels of NTx in 30 newly diagnosed MM patients and 25 controls. We examined its association with the overall score of skeletal involvement measured by Tc-99m-MIBI scintigraphy and other biochemical markers of bone disease (tumour necrosis factor a (TNF-a), serum calcium and creatinine). We further studied the correlation of NTx with the stage of disease (according to Durie-Salmon criteria) and bone marrow infiltration by plasma cells. High levels of NTx, bone marrow infiltration, TNF-alpha, calcium and creatinine were noted at advanced stages of disease (p < 0.05). NTx and TNF-a were found at significantly higher concentrations in patients with a high overall score (3 and 4) in Tc-99m-sestaMIBI in comparison to a low score (0, 1 and 2; p < 0.05). Positive correlations were found between NTx and TNF-a, as well as between bone infiltration and TNF-a or calcium. In conclusion, NTx is a useful marker for the monitoring of bone resorption in MM and correlates with imaging findings on Tc-99m-sestaMIBI and other biochemical markers of disease activity.

Evaluation of bone disease in multiple myeloma: a correlation between biochemical markers of bone metabolism and other clinical parameters in untreated multiple myeloma patients

INTRODUCTION

Multiple myeloma (MM) is characterised by an uncoupled bone formation/resorption process resulting in osteolysis. Osteocalcin (OC) and bone-specific alkaline phosphatase (BAP) are markers of osteoblastic activity, whereas pyridinoline products and the cross-linked aminoterminal of type I collagen (NTx) reflect bone destruction. In this study, these markers were studied in relation to bone disease severity and other clinical parameters of MM activity.

METHODS

Serum calcium, creatinine, CRP, beta 2 microglobulin (b(2)M), M-component, OC, BAP and free urine pyridoline (Pyd) and deoxypyridinoline (Dpd), free urine Dpd and NTx were determined in 38 newly diagnosed MM patients. X-ray examination defined the degree of bone involvement. Patients were classified according to the Durie-Salmon staging system.

RESULTS

NTx, free urine Pyd + Dpd, and free urine Dpd increased with increasing degree of bone involvement. NTx was significantly higher in stages II and III compared to stage I (mean values: 100.7, 163.5 and 208.3 nmol BCE/mM creat, respectively, p < 0.002). Free urine Pyd + Dpd correlated positively with b(2)M and CRP. OC was increased in stages I and II compared to III (p < 0.005) and was inversely correlated with NTx, free urine Pyd + Dpd, and free urine Dpd alone.

CONCLUSIONS

The measurement of bone turnover markers in MM provides significant information regarding disease progression and should be included in the evaluation of MM patients.

Bone mineral density in multiple myeloma patients after intravenous clodronate therapy

Bisphosphonates inhibit osteoclastic bone destruction that may be stimulated by myeloma cells. By this way, bisphosphonates carry the potential to lower the number of new pathological fractures, of hypercalcaemic events, and of intensity of bone pain as was published earlier. Clodronate has been administered orally in most clinical studies so far despite of its poor bioavailability from the gastrointestinal tract. The aim of our study was to evaluate bone mineral density (BMD) changes in 34 newly diagnosed multiple myeloma patients regularly treated by 900 mg of clodronate in slow intravenous infusions on an outpatient basis in two-week intervals for at least 24 months. BMD was evaluated by CT scanning every six months. Initial values of trabecular BMD were only about 60 per cent of age- and sex-adjusted healthy population values. Clodronate therapy seemed to preserve BMD within the period of two or three years. This effect was seen not only in patients responding to chemotherapy but even in the small subgroup of patients with persisting active disease. We conclude that the long-term intravenous clodronate therapy may contribute to the preservation of BMD and thus calcium hydroxyapatite in bones in multiple myeloma patients concomitantly treated by chemotherapy. The administration of clodronate should start early in the course of disease, before BMD has been markedly reduced.

Current drug therapy for multiple myeloma

Recent years have witnessed tremendous advances in the molecular pathogenesis and management of multiple myeloma. Standard chemotherapy (melphalan and prednisone; MP) has been the mainstay of treatment of multiple myeloma for about 3 decades. However, it is no longer considered the 'gold standard', particularly for those patients who will subsequently undergo intensive chemotherapy with autologous or allogeneic peripheral blood stem cell (PBSC) or bone marrow transplantation (BMT), or for patients with refractory myeloma. A variety of induction combination chemotherapy regimens have been developed, some of which have demonstrated an improved response rate and duration and a superior 5-year survival rate when compared with standard chemotherapy. The early use of high dose chemotherapy with autologous PBSC support or BMT has significantly increased the complete remission rate, and has prolonged event-free sur vival and overall survival. Allogeneic bone marrow or PBSC transplantation may be a good option for selected patients with poor prognostic features. The role of interferon-alpha in multiple myeloma is still inconclusive despite many years of clinical evaluation. The clinical application of chemosensitising agents that can inhibit P-glycoprotein (P-gp) expression and function, and particularly the development of more potent P-gp modulators such as valspodar (PSC 833) and elacridar (GF120918) has made it possible to reverse multidrug resistance in some refractory patients and to enhance the efficacy of chemotherapeutic agents. Immunotherapeutic approaches to purging of autologous bone marrow or PBSC, or as adjuvant therapy for minimal residual disease, show great promise. Finally, a number of new therapies specifically designed to treat many of the complications of multiple myeloma are improving clinical outcomes and quality of life for these patients.