Pamidronate increases markers of bone formation in patients with multiple myeloma in plateau phase under interferon-alpha treatment

The role of bisphosphonates in multiple myeloma: mechanisms, side effects, and the future

Zoledronic acid and pamidronate are two potent anticatabolic nitrogen-containing bisphosphonates (BPs) used extensively in diseases with high bone turnover such as multiple myeloma (MM). In this review we focus on their biology and their current and future use in MM, and highlight some of the most common and emerging side effects. Although the primary target cells for BPs are osteoclasts, new insights suggest other cell types of the bone microenvironment as possible targets, including osteoblasts, endothelial cells, immune cells, and cancer cells. Here, we focus on the current guidelines for the use of BPs in MM and address side effects such as renal toxicity, osteonecrosis of the jaw, and low-energy fractures. Finally, we approach the future of BP use in MM in the context of other bone-targeted agents, evaluating ongoing clinical trials addressing alternate dosing and schedules of BP administration in MM patients.

Mechanisms of interferon-beta effects on bone homeostasis

Restoration of dysregulated bone homeostasis is a therapeutic goal in many diseases including osteoporosis, rheumatoid arthritis and metastatic cancer. The molecular pathways regulating bone remodeling are major therapeutic targets, and studies continue to reveal endogenous factors that may be pathologically up- or down-regulated and lead to an uncoupling of bone formation and resorption. The purpose of this commentary is to highlight new mechanisms of bone homeostatic regulation mediated through the induction of endogenous interferon-beta (IFN-beta). The receptor activator of nuclear factor-kappaB (RANK) ligand (RANKL) is an important factor in the bone resorption cascade, and the RANK-RANKL interaction has been shown to induce IFN-beta and osteoclastogenesis via induction of the c-fos gene. Subsequent binding of IFN-beta to its biological receptor initiates a signal transduction cascade through the classic JAK/STAT pathway, causing an inhibition of c-fos protein production and osteoclast proliferation and differentiation (negative feedback). Another mechanism pertinent to the anti-resorptive effect of IFN-beta is the induction of nitric oxide which has been shown to inhibit osteoclast formation. The role of IFN-beta in bone metabolism could warrant its systematic evaluation as a potential adjunct to therapeutic regimens of osteolytic diseases. Here we also provide discussion of the potential challenges to optimizing IFN-beta pharmacotherapy for such purposes.

First-line therapy with thalidomide, dexamethasone and zoledronic acid decreases bone resorption markers in patients with multiple myeloma

BACKGROUND

Bone involvement is frequently observed in multiple myeloma (MM) patients both at diagnosis and during the course of the disease. The evaluation of biochemical markers of bone turnover could allow a dynamic evaluation of the effects of a given therapy on bone metabolism.

METHODS

In the present study, markers of bone resorption [urinary free pyridinoline (PYD), deoxypyridinoline (DPYD), N-terminal telopeptide of collagen I (NTX) and C-terminal telopeptide (serum crosslaps)] and of bone formation [bone alkaline phosphatase (BAP) and osteocalcin] were evaluated at diagnosis and after induction therapy in 40 patients (23M, 17F, median age = 53.5 yr) enrolled in the 'Bologna 2002' clinical trial. By study design, all patients received 4 months of combined thalidomide (100 mg/d for 2 wk then 200 mg/d), dexamethasone (40 mg/d on days 1-4, 9-12, 17-20/28 on odd cycles and on days 1-4 on even cycles) and zoledronic acid (4 mg/28 d).

RESULTS

At diagnosis, although bone resorption markers were increased in more than 40% of the patients, only NTX (P = 0.029) and crosslaps (P = 0.000) were significantly related to the extent of skeletal lesions, as assessed by X-ray. After 4 months of therapy, a significant decrease in mean (+/-SE) urinary NTX (52.7 +/-6.9 nmol/mmol creatinine +/-6.9 vs. 14 +/- 1.42 nmol/mmol creatinine, P = 0.000) and serum crosslaps (6242.4 +/-945 pmol/L vs. 1414.9 +/- 173.8 pmol/L, P = 0.000) was observed in patients obtaining > or =partial response, at variance to what has been detected in patients showing <partial response.

CONCLUSIONS

Among all bone resorption markers, urinary NTX and serum crosslaps seem to be strictly related to the extent of bone involvement in MM. Combined thalidomide + dexamethasone and zoledronic acid seem to be highly effective in reducing bone resorption in sensitive patients, although the relative contribution of each drug cannot yet be determined.

Biochemical markers of bone metabolism in multiple myeloma

Osteolytic bone disease is a major clinical feature of multiple myeloma (MM). Mechanisms of bone destruction are related to increased osteoclastic activity, which is not accompanied by a comparable increase in bone formation, as osteoblasts are functionally exhausted. Thus the lesions rarely heal and bone scans are often negative in myeloma patients with extensive lytic lesions, offering very little in the follow-up of bone disease. Biochemical markers of bone resorption, such as N- and C-terminal cross-linking telopeptide of type I collagen (NTX, CTX/ICTP, respectively), tartrate resistant acid phosphatase isoform-5b, bone formation (bone-specific alkaline phosphatase [BAP]), and osteocalcin provide useful information on bone dynamics. Several studies have shown that NTX, CTX, and ICTP are elevated in myeloma patients, reflect the extent of bone disease, and correlate with survival. Furthermore, they are useful in monitoring bone destruction during antimyeloma or bisphosphonate treatment. Markers of bone formation have produced conflicting results in trials. However, BAP correlates with bone pain, lytic lesions, and fractures in quite a few studies of MM. Novel markers, such as bone sialoprotein, receptor activator of nuclear factor-kappa B ligand (RANKL), osteoprotegerin, osteopontin, dickkopf-1, and soluble Frizzle-related protein-2 have been found of value in assessing bone lytic disease in MM, but their promising results must be confirmed in large trials. In conclusion, although no marker provides optimal analysis of MM or of MM treatments, combinations of markers have at times helped in assessing MM stages and lytic bone disease and in monitoring specific treatment modalities. The need for further research in this field is clear.

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.

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.

Tartrate-resistant acid phosphatase isoform 5b: a novel serum marker for monitoring bone disease in multiple myeloma

Tartrate-resistant acid phosphatase isoform-5b (TRACP-5b), a new marker reflecting osteoclast activity, and osteoprotegerin (OPG) were measured in 121 patients with multiple myeloma (MM) at diagnosis, and in 63 of them during pamidronate administration, to define their correlation with the extent of bone disease and disease activity in MM. Radiographic evaluation of the skeleton, measurement of other markers of bone remodelling, including N-terminal cross-linking telopeptide of type-I collagen (NTX), bone alkaline phosphatase and osteocalcin and of markers of disease activity (beta2-microglobulin, paraprotein, interleukin-6 (IL-6), were also performed. Levels of TRACP-5b were increased (p <.0001), while OPG was decreased in MM patients compared to controls (p <.01). TRACP-5b levels were associated with the radiographically assessed severity of bone disease (p <.0001) as well as with levels of NTX, IL-6 and beta2-microglobulin (p <.001, for each biochemical parameter, respectively). The combination of pamidronate with VAD-chemotherapy produced a reduction in TRACP-5b, NTX, IL-6, paraprotein and beta2-microglobulin levels from the 2nd month of treatment, with no effect on bone formation and OPG. A strong correlation was observed between changes in TRACP-5b and changes in NTX, IL-6 and beta2-microglobulin, while TRACP-5b predicted the disease progression in 5 patients. These findings suggest that TRACP-5b is increased in MM, reflects the extent of myeloma bone disease and may have a predictive value. TRACP-5b has also proved to be very useful for monitoring antimyeloma treatment, which had no effect on OPG levels.

Maintenance with pamidronate following first-line MP or VAD therapy in multiple myeloma

We investigated the anti-tumor effect of pamidronate after obtaining a decrease of serum monoclonal immunoglobulin (Ig) level by conventional chemotherapy in patients with multiple myeloma (MM) in order to evaluate whether the drug is useful as maintenance therapy for MM. Eight patients with MM received 60 mg/d pamidronate every third week for 6-18 months without chemotherapeutic agents or corticosteroids after the treatment with melphalan and prednisolone, or vincristine, adriamycin and prednisolone. Serum Ig and beta2-microglobulin (b2MG) levels were maintained at the levels obtained after the termination of chemotherapy in six and four out of eight patients, respectively. Hemoglobin levels were maintained at, or increased to more than, the levels observed at the end of chemotherapy in six patients. Decreased plasma cells in the bone marrow after the chemotherapy were evident in five patients. Two patients were categorized as non-responders, because Ig and b2MG increased and anemia progressed after treatment with the drug. Despite the very small numbers, the results suggest that pamidronate may have anti-tumor activity and be useful for treatment after the conventional chemotherapy in some cases of MM.

Pamidronate is superior to ibandronate in decreasing bone resorption, interleukin-6 and beta 2-microglobulin in multiple myeloma

OBJECTIVES

Bisphosphonates have been found to reduce skeletal events in patients with multiple myeloma (MM). This is the first randomised trial to compare the efficacy of pamidronate and ibandronate, a third-generation aminobisphosphonate, in bone turnover and disease activity in MM patients.

METHODS

Patients with MM, stage II or III, were randomly assigned to receive either pamidronate 90 mg (group I: 23 patients) or ibandronate 4 mg (group II: 21 patients) as a monthly intravenous infusion in addition to conventional chemotherapy. Skeletal events, such as pathologic fractures, hypercalcaemia, and bone radiotherapy were analysed. Bone resorption markers [N-terminal cross-linking telopeptide of type-I collagen (NTX) and tartrate-resistant acid phosphatase type 5b (TRACP-5b)], bone formation markers (bone alkaline phosphatase and osteocalcin), markers of disease activity (paraprotein, CRP, beta 2-microglobulin), and interleukin-6 (IL-6) were also studied.

RESULTS

In both groups, the combination of chemotherapy with either pamidronate or ibandronate produced a reduction in bone resorption and tumour burden as measured by NTX, IL-6, paraprotein, CRP, and beta 2-microglobulin from the second month of treatment, having no effect on bone formation. TRACP-5b also had a significant reduction in the pamidronate group from the second month of treatment and in the ibandronate group from the sixth month. However, there was a greater reduction of NTX, IL-6, and beta 2-microglobulin in group I than in group II, starting at the second month of treatment (P = 0.002, 0.001, and 0.004, respectively) and of TRACP-5b, starting at the fourth month (P = 0.014), that being continued throughout the 10-month follow-up of this study. There was no difference in skeletal events during this period. A significant correlation was observed between changes of NTX and changes of TRACP-5b, IL-6, and beta 2-microglobulin from the second month for patients of both groups.

CONCLUSIONS

These results suggest that a monthly dose of 90 mg of pamidronate is more effective than 4 mg of ibandronate in reducing osteoclast activity, bone resorption, IL-6, and possibly tumour burden in MM. TRACP-5b has also proved to be a useful new marker for monitoring bisphosphonates treatment in MM.

Bisphosphonate therapy in multiple myeloma: past, present, future

Bone disease characterised by osteolytic lesions, pathological fractures and hypercalcaemia is an important clinical feature in multiple myeloma. Pain, decreased performance status, and the need for palliative radiotherapy and surgical interventions are common sequelae. Bisphosphonates act primarily on osteoclasts to inhibit excessive bone resorption, and have therefore been investigated in myeloma patients to ameliorate the clinical consequences of the bone disease. Bisphosphonates are currently the therapy of choice in myeloma patients with hypercalcaemia. In long-term management, both oral clodronate and intravenous pamidronate are effective in reducing skeletal-related events. Zoledronic acid seems to be as effective as pamidronate. Whether bisphosphonates have antimyeloma activity is currently unknown. Cost-benefit analyses have shown reasonable efficacy with acceptable costs. Bisphosphonate therapy is now accepted as an important part of care in myeloma patients, although much still has to be learned in order to optimise this therapy in multiple myeloma.