Soluble receptor activator of nuclear factor kappaB ligand-osteoprotegerin ratio predicts survival in multiple myeloma: proposal for a novel prognostic index

Myeloma bone disease: pathophysiology and management

Bone disease is a major feature of multiple myeloma. Myeloma-induced bone destruction is the result of an increased activity of osteoclasts, which is not accompanied by a comparable increase of osteoblast function. Recent studies have revealed that new molecules such as the receptor activator of nuclear factor-kappa B (RANK), its ligand (RANKL), osteoprotegerin (OPG), and macrophage inflammatory protein-1alpha are implicated in osteoclast activation and differentiation, while proteins such as dickkopf-1 inhibit osteoblastic bone formation. These new molecules seem to interfere not only with the biology of myeloma bone destruction but also with tumour growth and survival, creating novel targets for the development of new antimyeloma treatment. Currently, bisphosphonates play a major role in the management of myeloma bone disease. Clodronate, pamidronate and zoledronic acid are the most effective bisphosphonates in symptomatic myeloma patients. Biochemical markers of bone remodeling have been used in an attempt to identify patients more likely to benefit from early treatment with bisphosphonates. Furthermore, using microarray techniques, myeloma patients may be subdivided into molecular subgroups with certain clinical characteristics, such as propensity for lytic lesions that may need early prophylactic treatment. Recent phase I studies with recombinant OPG and monoclonal antibodies to RANKL appear promising.

The role of markers of bone remodeling in multiple myeloma

Osteolytic bone disease is a frequent complication of multiple myeloma, resulting in skeletal complications that are a significant cause of morbidity and mortality. A characteristic feature of myeloma bone disease is that the lesions rarely heal and bone scans are often negative in myeloma patients who have extensive lytic lesions, offering very little in the follow-up of bone disease. X-rays are also of limited value in monitoring bone destruction during anti-myeloma or anti-resorptive treatment. Biochemical markers of bone turnover, such as N- and C-terminal cross-linking telopeptide of type I collagen (NTX, CTX/ICTP, respectively), and newer ones such as the tartrate resistant acid phosphatase isoform 5b, provide information on bone dynamics that in turn may reflect disease activity in bone. Several studies have shown bone markers to be elevated in myeloma patients and reflect the extent of bone disease, while in some of them bone resorption markers correlate with survival. These markers may also be helpful in identifying those patients likely to respond to bisphosphonate treatment, and monitoring the effectiveness of bisphosphonate therapy in the management of myeloma bone disease. This review attempts to summarize the existing data for the role of markers of bone remodeling in assessing the extent of bone destruction in myeloma and monitoring bone turnover during specific anti-myeloma treatment. We also discuss some novel markers that may be of particular interest in the near future.

Immunoglobulin M Myeloma: Evaluation of Molecular Features and Cytokine Expression

Immunoglobulin (Ig) M myeloma is a distinct entity with features of multiple myeloma (MM) and Waldenstrom's macroglobulinemia (WM). The malignant cells in IgM myeloma have a distinctive chromosomal translocation that differentiates them from WM. These cells are postgerminal-center in origin with isotype-switch transcripts. They appear to be arrested at a point of maturation between that of WM and MM. Preliminary data indicate that a pattern of osteoclast-activating factor and osteoprotegerin expression similar to that observed in classic MM is present in IgM myeloma. Additional studies on patients with this rare tumor may provide further insight into the pathogenesis of bone disease in plasma cell dyscrasias.

Relationships between the changes of serum levels of OPG and RANKL with age, menopause, bone biochemical markers and bone mineral density in Chinese women aged 20-75

The correlations between the serum levels of OPG, RANKL with age, menopause, bone markers, and bone mineral densities (BMDs) at the lumbar spine and proximal femur were studied in 504 pre- and postmenopausal Chinese women aged 20-75 years. We found that age was positively and negatively correlated with serum concentrations of OPG (r = 0.442, P < 0.001) and RANKL (r = -0.263, P < 0.001), respectively. Compared with premenopausal women, postmenopausal women showed higher serum OPG levels (107.6 +/- 3.0 vs 72.0 +/- 1.8 pg/ml, P < 0.001), lower serum RANKL concentrations (4.7 +/- 0.4 vs. 5.8 +/- 0.3 pg/ml, P < 0.001) and RANKL/OPG ratios (0.045 +/- 0. 004 vs. 0.099 +/- 0.008, P < 0.001). Neither serum levels of OPG nor RANKL or RANKL/OPG ratio correlated with BMDs after adjustment of age and menopause. They also showed no differences among normal, osteopenic and osteoporotic postmenopausal women. Serum levels of OPG were positively correlated with urinary excretion of NTx (r = 0.1453, P = 0.006). Serum levels of RANKL (r = -0.1928, P < 0.001) and RANKL/OPG ratio (r = -0.1303, P = 0.013) were inversely correlated with serum concentrations of OC. In multiple regression analysis, up to 20% variance (R(2) = 0.106-0.224) of the OPG-RANKL system in peripheral circulation can be explained by age, menopause and bone markers. These results suggest that although serum OPG and RANKL concentrations were unrelated with BMDs, the age- and menopause- dependent changes of serum OPG and RANKL might be a protective mechanism against the accelerated bone loss in postmenopausal women.

Regulation of synthesis of osteoprotegerin and soluble receptor activator of nuclear factor-kappaB ligand in normal human osteoblasts via the p38 mitogen-activated protein kinase pathway by the application of cyclic tensile strain

Mechanical stress is thought to play an important role in bone remodeling. However, the correlation between mechanical stress and bone remodeling is poorly understood. In this context, using a model of cyclic tensile strain (CTS) toward human osteoblasts, synthesis of osteoprotegerin (OPG) and soluble receptor activator of nuclear factor-kappaB ligand (sRANKL), and the activation of mitogen-activated protein kinases (MAPKs) were examined. The application of 7%, 0.25-Hz CTS once a day for 4 h for 3 successive days simultaneously caused an increase of OPG synthesis and a decrease of sRANKL release and RANKL mRNA expression in osteoblasts. As for MAPKs activation in osteoblasts with the application of CTS, p38 MAPK was activated 10-20 min after the application of CTS, but extracellular signal-regulated kinase (ERK1/2) and c-Jun NH2-terminal kinase (JNK) were not activated by such application. Furthermore, when CTS was applied once a day for 4 h for 1, 2, or 3 successive days to osteoblasts, p38 MAPK activation was maintained during the 3-day period but ERK1/2 activation was downregulated from day to day, simultaneously. Then, when CTS was applied once a day for 4 h for 3 successive days to osteoblasts pretreated with the p38 MAPK inhibitor SB203580 for 1 h, OPG synthesis was dose-dependently suppressed and inhibition of sRANKL release and RANKL mRNA expression was abrogated. These results indicate that biological responses of OPG and sRANKL synthesis in osteoblasts to the application of CTS are regulated via the p38 MAPK pathway and suggest that CTS might modulate and regulate bone metabolism.

The molecular triad OPG/RANK/RANKL: involvement in the orchestration of pathophysiological bone remodeling

The past decade has seen an explosion in the field of bone biology. The area of bone biology over this period of time has been marked by a number of key discoveries that have opened up entirely new areas for investigation. The recent identification of the receptor activator of nuclear factor kappaB ligand (RANKL), its cognate receptor RANK, and its decoy receptor osteoprotegerin (OPG) has led to a new molecular perspective on osteoclast biology and bone homeostasis. Specifically, the interaction between RANKL and RANK has been shown to be required for osteoclast differentiation. The third protagonist, OPG, acts as a soluble receptor antagonist for RANKL that prevents it from binding to and activating RANK. Any dysregulation of their respective expression leads to pathological conditions such as bone tumor-associated osteolysis, immune disease, or cardiovascular pathology. In this context, the OPG/RANK/RANKL triad opens novel therapeutic areas in diseases characterized by excessive bone resorption. The present article is an update and extension of an earlier review published by Kwan Tat et al. [Kwan Tat S, Padrines M, Theoleyre S, Heymann D, Fortun Y. IL-6, RANKL, TNF-alpha/IL-1: interrelations in bone resorption pathophysiology. Cytokine Growth Factor Rev 2004;15:49-60].

RANKL/RANK/OPG: new therapeutic targets in bone tumours and associated osteolysis

The emergence of the molecular triad osteoprotegerin (OPG)/Receptor Activator of NF-kB (RANK)/RANK Ligand (RANKL) has helped elucidate a key signalling pathway between stromal cells and osteoclasts. The interaction between RANK and RANKL plays a critical role in promoting osteoclast differentiation and activation leading to bone resorption. OPG is a soluble decoy receptor for RANKL that blocks osteoclast formation by inhibiting RANKL binding to RANK. The OPG/RANK/RANKL system has been shown to be abnormally regulated in several malignant osteolytic pathologies such as multiple myeloma [MM, where enhanced RANKL expression (directly by tumour cells or indirectly by stromal bone cells or T-lymphocytes)] plays an important role in associated bone destruction. By contrast, production of its endogenous counteracting decoy receptor OPG is either inhibited or too low to compensate for the increase in RANKL production. Therefore, targeting the OPG/RANK/RANKL axis may offer a novel therapeutic approach to malignant osteolytic pathologies. In animal models, OPG or soluble RANK was shown both to control hypercalcaemia of malignancy and the establishment and progression of osteolytic metastases caused by various malignant tumours. To this day, only one phase I study has been performed using a recombinant OPG construct that suppressed bone resorption in patients with multiple myeloma or breast carcinoma with radiologically confirmed bone lesions. RANK-Fc also exhibits promising therapeutic effects, as revealed in animal models of prostate cancer and multiple myeloma. If the animal results translate to similar clinical benefits in humans, using RANK-Fc or OPG may yield novel and potent strategies for treating patients with established or imminent malignant bone diseases and where standard therapeutic regimens have failed.

Role of receptor activator of nuclear factor-kappa B ligand (RANKL), osteoprotegerin and macrophage protein 1-alpha (MIP-1a) in monoclonal gammopathy of undetermined significance (MGUS)

The aim of this study was to evaluate the role of markers of bone remodelling, and osteoclast activation/function in patients with monoclonal gammopathy of undetermined significance (MGUS). We have measured serum levels of soluble RANKL (sRANKL), osteoprotegerin (OPG), macrophage inflammatory protein-1alpha (MIP-1alpha), markers of bone resorption [N-telopeptide of collagen type-I (NTX), and tartrate-resistant acid phosphatase isoform-5b (TRACP-5b)] and bone formation [bone-alkaline phosphatase (bALP)] in 40 MGUS patients. These parameters were compared with those of 42 newly diagnosed myeloma patients, and 45 healthy, gender- and age-matched controls. MGUS patients had elevated levels of NTX, sRANKL, and sRANKL/OPG ratio compared with controls (P < 0.0001). Furthermore, TRACP-5b, MIP-1alpha and NTX were decreased in patients with MGUS compared with myeloma patients (P < 0.001), while OPG and bALP were increased (P < 0.001). Serum levels of MIP-1alpha, as well as TRACP-5b, and sRANKL/OPG ratio were reduced, while bALP was increased in MGUS patients, even when compared with myeloma patients who had stage I/II disease. These results demonstrate that increased osteoclastogenesis leading to increased bone resorption is present in MGUS but seems to be compensated for by normal bone formation, which is absent in MM. Furthermore MIP-1alpha, bALP, and sRANKL/OPG may be useful tools for distinguishing between cases of MGUS and early myeloma.

IL-6, RANKL, TNF-alpha/IL-1: interrelations in bone resorption pathophysiology

All osteogenic cells (osteoclasts, osteoblasts) contribute individually to bone remodeling. Their cellular interactions control their cellular activities and the bone remodeling intensity. These interactions can be established either through a cell-cell contact, involving molecules of the integrin family, or by the release of many polypeptidic factors and/or their soluble receptor chains. These factors can act directly on osteogenic cells and their precursors to control differentiation, formation and functions (matrix formation, mineralization, resorption...). Here, we present the involvement of three groups of cytokines which seem to be of particular importance in bone physiology: interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) (TNF-alpha)/IL-1, and the more recently known triad osteoprotegerin (OPG)/receptor activator of NF-kappaB (RANK)/RANK ligand (RANKL). The interactions between these three groups are presented within the framework of bone resorption pathophysiology such as tumor associated osteolysis. The central role of the OPG/RANK/RANKL triad is pointed out.

New insight in the mechanism of osteoclast activation and formation in multiple myeloma: focus on the receptor activator of NF-kappaB ligand (RANKL)

The increase of osteoclast activation and formation is mainly involved in the development of the osteolytic bone lesions that characterize multiple myeloma (MM) patients. The mechanisms by which myeloma cells induce bone resorption have not been clear for many years. Recently, new evidence has elucidated which factors are critically involved in the activation of osteoclastic cells in MM. The potential role of the critical osteoclastogenic factor, the receptor activator of NF-kappaB ligand (RANKL), and its soluble antagonist osteoprotegerin (OPG) in the activation of bone resorption in MM is summarized in this review. It has been demonstrated that human MM cells induce an imbalance in the bone marrow environment of the RANKL/OPG ratio in favor of RANKL that triggers the osteoclast formation and activation leading to bone destruction. The direct production of the chemokine macrophage inflammatory protein-1 alpha (MIP-1alpha) by myeloma cells, in combination with the RANKL induction in BM stromal cells in response to myeloma cells, are critical in osteoclast activation and osteoclastogenesis.

Vitamin A differentially regulates RANKL and OPG expression in human osteoblasts

All-trans-retinoic acid (ATRA) induces bone resorption, but the molecular mechanisms are unknown. We have studied the effect of ATRA on osteoprotegerin (OPG) and receptor activator of NF-kappaB ligand (RANKL) expression in human MG-63 osteosarcoma cells and primary osteoblast-like cultures. ATRA dose-dependently down-regulated protein levels of OPG in MG-63 cells, with a maximum (-56%) observed at a dose of 10(-6)M. This effect was confirmed with quantitative real-time PCR, where OPG mRNA was decreased after 4h (-68%) in primary cultures and after 8h (-87%) in MG-63 cells. The reduction in OPG expression was inhibited by a retinoic acid receptor (RAR)-antagonist and was mimicked by a RARbeta,gamma-agonist, indicating that the ATRA effect is mediated by these receptors. In primary cultures we found a threefold induction of RANKL mRNA expression. Thus, the RANKL/OPG ratio was markedly increased, suggesting a potential mechanism of ATRA-induced bone resorption.

Differential expression of RANKL and osteoprotegerin in gingival crevicular fluid of patients with periodontitis

The receptor activator for NF-kappaB ligand (RANKL) plays an important role in osteoclast formation. A recent study with animal models suggests the involvement of RANKL in the pathogenesis of this periodontal disease. However, no one has examined the level of RANKL in the body fluid of human subjects. This communication reports on the in vivo concentrations of RANKL and the RANKL decoy receptor osteoprotegerin (OPG) in the gingival crevicular fluid (GCF) of periodontal subjects with severe, moderate, and mild forms of the disease. An increased concentration of RANKL and a decreased concentration of OPG were detected in GCF from patients with periodontitis (*p < 0.05 vs. control subjects). The ratio of the concentration of RANKL to that of OPG in the GCF was significantly higher for periodontal disease patients than for healthy subjects (*p < 0.01). Taken together, these data suggest that RANKL and OPG contribute to osteoclastic bone destruction in periodontal disease.

ABBREVIATIONS

GCF, gingival crevicular fluid; IL, interleukin; OPG, osteoprotegerin; RANKL, receptor activator for NF-kappaB ligand.

Autologous stem cell transplantation normalizes abnormal bone remodeling and sRANKL/osteoprotegerin ratio in patients with multiple myeloma

The osteoprotegerin (OPG)/receptor activator of NF-kappa B ligand (RANKL) system has a major role in the pathogenesis of bone disease in myeloma (MM). The effect of autologous stem cell transplantation (ASCT) on bone turnover in MM was evaluated in 51 patients (35M/16F). Markers of bone resorption (NTX, TRACP-5b), bone formation (bone-alkaline phosphatase (bALP), osteocalcin), OPG and sRANKL were measured pre- and every month post-ASCT. The median follow-up period was 12 months. Four patients were transplanted in CR, 44 were transplanted in PR and three patients had progressive/resistant disease. All patients received bisphosphonates both pre- and post-ASCT. At baseline the majority of patients had increased NTX, TRACP-5b levels, and sRANKL/OPG ratio, while markers of bone formation were strongly suppressed. ASCT produced a significant reduction of sRANKL/OPG ratio, with a concomitant decrease of NTX, and TRACP-5b levels, starting the second month post-ASCT. Bone formation markers, osteocalcin and bALP, started to increase after the 9th and 11th month post-ASCT, respectively, while the increase of OPG preceded this. These results provide biochemical evidence that ASCT normalizes the abnormal bone resorption in MM patients possibly through the decrease of RANKL/OPG ratio, while bone formation requires a longer period to return to normal.

Osteoprotegerin and RANKL in the pathogenesis of thalassemia-induced osteoporosis: new pieces of the puzzle

Osteoporosis represents an important cause of morbidity in adult thalassemic patients, and its pathogenesis has not, as yet, been completely clarified. In our study, we observed that thalassemic patients showed a significantly lower OPG/RANKL ratio than normal subjects. These data are extremely important for the possible therapeutic use of RANKL antagonists such as OPG in thalassemia-induced osteoporosis.

INTRODUCTION

Osteoporosis represents an important cause of morbidity in adult thalassemic patients who display increased fracture risk. The etiology of this bone disease is multifactorial, but it is thought that the main role is played by hypogonadism. The mechanisms by which the skeletal effects of sex steroids are mediated are still not fully understood. Recently, two new cytokines, osteoprotegerin (OPG) and RANKL, have been implicated in the pathogenesis of postmenopausal osteoporosis and other metabolic bone diseases. Thus, the aim of this study was to characterize the possible role of the OPG/RANKL system in thalassemia-related bone loss.

MATERIALS AND METHODS

We measured, in 30 thalassemic patients and in 20 healthy control subjects, serum OPG and RANKL levels, and determined their correlations with bone turnover markers, BMD, sex steroid levels, erythropoietin, and hemoglobin.

RESULTS

Thalassemic patients had an unbalanced bone turnover with an increased resorption phase (shown by high levels of pyridinium cross-links) and a decreased neoformation phase (shown by the slightly low levels of osteocalcin). Moreover, they displayed lower BMD values than controls both at the lumbar and femoral level. As far as the OPG/RANKL system is concerned, thalassemic patients showed no differences in plasma levels of OPG compared with controls, and significantly higher plasma levels of RANKL, with a consequent significantly lower OPG/RANKL ratio.

CONCLUSIONS

Our data suggest that, in thalassemic patients, an altered modulation of the OPG/RANKL system, resulting in increased expression of RANKL by stromal or osteoblastic cells, could contribute to the enhanced osteoclastic bone resorption and bone loss characteristic of these patients.

The role of the Wnt-signaling antagonist DKK1 in the development of osteolytic lesions in multiple myeloma

BACKGROUND

Myeloma cells may secrete factors that affect the function of osteoblasts, osteoclasts, or both.

METHODS

We subjected purified plasma cells from the bone marrow of patients with newly diagnosed multiple myeloma and control subjects to oligonucleotide microarray profiling and biochemical and immunohistochemical analyses to identify molecular determinants of osteolytic lesions.

RESULTS

We studied 45 control subjects, 36 patients with multiple myeloma in whom focal lesions of bone could not be detected by magnetic resonance imaging (MRI), and 137 patients in whom MRI detected such lesions. Different patterns of expression of 57 of approximately 10,000 genes from purified myeloma cells could be used to distinguish the two groups of patients (P<0.001). Permutation analysis, which adjusts the significance level to account for multiple comparisons in the data sets, showed that 4 of these 57 genes were significantly overexpressed by plasma cells from patients with focal lesions. One of these genes, dickkopf 1 (DKK1), and its corresponding protein (DKK1) were studied in detail because DKK1 is a secreted factor that has been linked to the function of osteoblasts. Immunohistochemical analysis of bone marrow-biopsy specimens showed that only myeloma cells contained detectable DKK1. Elevated DKK1 levels in bone marrow plasma and peripheral blood from patients with multiple myeloma correlated with the gene-expression patterns of DKK1 and were associated with the presence of focal bone lesions. Recombinant human DKK1 or bone marrow serum containing an elevated level of DKK1 inhibited the differentiation of osteoblast precursor cells in vitro.

CONCLUSIONS

The production of DKK1, an inhibitor of osteoblast differentiation, by myeloma cells is associated with the presence of lytic bone lesions in patients with multiple myeloma.

Unusual association between increased bone resorption and presence of paroxysmal nocturnal hemoglobinuria phenotype in multiple myeloma

Paroxysmal nocturnal hemoglobinuria (PNH) clones deficient in glycosylphosphatidylinositol-anchored molecules, including CD55 and CD59, have been previously described in patients with multiple myeloma (MM). The aim of this study was to investigate the possible association between existence of the PNH phenotype and myeloma bone disease. Forty-three patients with newly diagnosed MM were the subjects of the study. Radiographic evaluation of the skeleton was performed in all patients at diagnosis. The following biochemical markers were measured: bone resorption markers (tartrate-resistant acid phosphatase isoform 5b [TRACP-5b]and N-terminal cross-linking telopeptide of type-I collagen [NTX]), bone formation markers (bone alkaline phosphatase [bALP] and osteocalcin [OC]), osteoprotegerin (OPG), soluble receptor activator of nuclear factor KB ligand (sRANKL), and interleukin 6 (IL-6). Detection of CD55- and/or CD59-deficient red cell populations was performed after diagnosis. Patients with MM had elevated mean baseline NTX, TRACP-5b, sRANKL, and IL-6 levels compared with controls, whereas the mean values of bALP, OC, and OPG were significantly decreased. Four patients had no osteolytic lesions, whereas 8 patients had 1 to 3 lytic lesions, and 31 patients had more than 3 lytic lesions and/or pathologic fractures in the skeletal survey. CD55- and/or CD59-deficient red cell populations were observed in 56% of patients with MM. There was a strong correlation between the presence of PNH-like erythrocytes and increased bone resorption, as measured by NTX, TRACP-5b, and sRANKL/OPG ratio (P < .03, P < .02, and P < .02, respectively). There was also a significant correlation between PNH phenotype and severe bone disease (P < .02). These results suggest that there is a possible link between PNH phenotype and increased osteoclastic activity in MM owing to a potential effect of myeloma microenvironment on a preexisting PNH clone. Further studies are required for clarifying this phenomenon and investigating possible mechanisms of this unusual association.

Receptor activator of nuclear factor kappaB ligand (RANKL)/osteoprotegerin (OPG) ratio is increased in severe osteolysis

Pathological osteolyses are considered a consequence of a disturbance in the mechanisms that govern the bone remodeling, mainly the communication between osteoclasts and osteoblasts. Osteoprotegerin (OPG) and receptor activator of NF-kappaB ligand (RANKL) are newly discovered molecules that play a key role in these communications. RANKL is essential for osteoclast differentiation via its receptor RANK located on the osteoclast membrane. OPG is a soluble decoy receptor that inhibits osteoclast differentiation through its binding to RANKL. The aim of this study is the analysis of the RANKL/OPG balance by complementary methods (semiquantitative reverse transcription-polymerase chain reaction, immunohistochemistry, and enzyme-linked immunosorbent assay) in human osteolysis associated to various bone etiologies (n = 60), tumoral (primitive, secondary) or not, compared to healthy tissues (n = 16). Results demonstrated that RANKL/OPG ratio was significantly increased in patients suffering from severe osteolysis compared to the control group and that this imbalance is involved in bone resorption mechanisms. In this study, OPG expression appears to reflect a protective mechanism of the skeleton to compensate increased bone resorption by inhibiting osteoclast formation and bone resorbing activity. Moreover, as revealed by immunohistochemistry, RANKL and OPG were colocalized in all of the tissues analyzed. To define the veracity of RANKL/OPG index in assessing and managing patients with severe osteolysis, an extended population of patients suffering from severe osteolysis must be now monitored.

Pamidronate is an effective treatment for osteoporosis in patients with beta-thalassaemia

Osteoporosis in beta-thalassaemia is multifactorial; increased osteoclast function seems to play an important role in its pathogenesis. The aim of this study was to evaluate the effect of pamidronate on the osteoporosis of thalassaemia. To this effect we studied 26 patients who received this drug in doses of 30 or 60 mg i.v. once a month over 12 months. The effects were monitored by measuring bone mineral density (BMD) in association with markers of osteoclast function [soluble receptor activator of nuclear factor-kappa B ligand (sRANKL), osteoprotegerin (OPG)] and of bone remodelling [N-telopeptide of collagen type-I (NTX), tartrate-resistant acid phosphatase isoform-5b (TRACP-5b), bone-alkaline phosphatase (bALP), and osteocalcin (OC)]. Thirty healthy individuals were also studied, as controls. NTX, TRACP-5b, bALP and OC levels were significantly higher in thalassaemic patients compared with controls; in contrast, OPG levels were significantly lower, while the levels of sRANKL varied within normal limits. Administration of pamidronate was followed by a clear decrease of NTX, TRACP-5b, OPG, and OC, and by a significant increase in the BMD of the lumbar spine, which was similar in patients of both treatment groups. These data suggest that pamidronate, at a monthly dose of 30 mg, is an effective treatment for thalassaemic osteoporosis.

Clinical review 165: Markers of bone remodeling in metastatic bone disease

Many cancers have a strong propensity to spread to bone. The processes involved in cancer dissemination to bone are complex and variable, and the changes in bone metabolism, once bony metastases have occurred, are usually profound. This review surveys the usefulness of bone markers in the diagnosis and follow-up of patients with malignant bone disease. In patients with established bone metastases, most markers of bone remodeling are abnormal compared with healthy controls or cancer patients without bone lesions. Although bone markers may have a potential as diagnostic tools in cancer patients, the available data do not allow final conclusions regarding the accuracy and validity of any of the presently used markers in the diagnosis of bone metastases. As regards monitoring of anticancer therapy, most markers of bone remodeling respond to active treatments. These indices therefore may have the potential to be used in the monitoring of antitumor therapies. However, most if not all of the available evidence on the use of bone markers in monitoring anticancer therapy is observational, and it remains unclear whether they have any beneficial effects on overall outcome. The same is true for their prognostic value, although evidence suggests that suppressed levels of bone formation or high rates of bone resorption are independent predictors of poor survival.