Failure of oral pamidronate to reduce skeletal morbidity in multiple myeloma: a double-blind placebo-controlled trial. Danish-Swedish co-operative study group

Prevention Of Skeletal Related Events In Multiple Myeloma: Focus On The RANK-L Pathway In The Treatment Of Multiple Myeloma

More than 90% of patients with multiple myeloma (MM) have osteolytic bone lesions which increase the risk of skeletal-related events (SRE). The cytokine milieu in the bone marrow microenvironment (BMME) of MM plays a key role in myeloma bone disease by impairing the balance between osteoclastogenesis and osteoblastogenesis. This is orchestrated by the malignant plasma cell (MPC) with the ultimate outcome of MPC proliferation and survival at the expense of excess osteoclast activation resulting in osteolytic bone lesions. Prevention of SRE is currently accomplished by the inhibition of osteoclasts. Bisphosphonates (BPs) are pyrophosphate analogues that cause apoptosis of osteoclasts and have been proven to prevent and delay SRE. Denosumab, a fully humanized monoclonal antibody that binds and inhibits receptor activator of nuclear factor-ĸB ligand (RANKL), a key molecule in the BMME crucial for osteoclastogenesis, is also approved for the prevention of SRE in MM. The addition of BPs and denosumab to standard MM treatment affords a survival benefit for patients with MM. Specifically, the addition of denosumab to standard MM treatments results in superior PFS compared to BPs, highlighting the key role of the RANKL pathway in MM. This review focuses on the pathophysiology of myeloma bone disease as well as on the importance of targeting the RANK-L pathway for the treatment of MM and prevention of SRE.

Bisphosphonates in Oncology: Physiopathologic Bases and Clinical Activity

Osteoclastic activation is the ultimate way of bone resorption in neoplasia, induced by the combined effects of tumor-secreted humoral factors (especially parathyroid hormone-related peptides) and osteoclastic-osteoblastic interaction. Bisphosphonates inhibit the osteoclast activity and reduce bone resorption and are a valuable supportive measure for bone disease of neoplasms. Experimental models also suggest an activity of bisphosphonates against cancer cells. Controlled studies, especially in advanced breast cancer and multiple myeloma, indicate different effectiveness against the distinct skeletal-related events. Intravenous clodronate and, especially, pamidronate and zoledronate are the first-choice drugs for hypercalcemia, and they play a significant role in reducing metastatic bone pain. Their prolonged use delays, without hampering, the progression of bone disease, including the appearance of osteolysis and the occurrence of pathologic fractures. This effect is probably more valuable when bisphosphonates are administered early in the course of the disease. The evidence that adjuvant bisphosphonates improve survival needs to be confirmed in ongoing studies. Although poorly absorbed by the gastrointestinal tract, oral bisphosphonates are effective in preventing and treating cancer-induced osteoporosis in long-living patients with operable breast cancer. At present, there is little hope that newer bisphosphonates are more effective than those currently used.

Bisphosphonates in multiple myeloma: an updated network meta-analysis

BACKGROUND

Bisphosphonates are specific inhibitors of osteoclastic activity and are used in the treatment of patients with multiple myeloma (MM). While bisphosphonates are shown to be effective in reducing vertebral fractures and pain, their role in improving overall survival (OS) remains unclear. This is an update of a Cochrane review first published in 2002 and previously updated in 2010 and 2012.

OBJECTIVES

To assess the evidence related to benefits and harms associated with use of various types of bisphosphonates (aminobisphosphonates versus non-aminobisphosphonates) in the management of patients with MM. Our primary objective was to determine whether adding bisphosphonates to standard therapy in MM improves OS and progression-free survival (PFS), and decreases skeletal-related morbidity. Our secondary objectives were to determine the effects of bisphosphonates on pain, quality of life, incidence of hypercalcemia, incidence of bisphosphonate-related gastrointestinal toxicities, osteonecrosis of jaw (ONJ) and hypocalcemia.

SEARCH METHODS

We searched MEDLINE, Embase (September 2011 to July 2017) and the CENTRAL (2017, Issue 7) to identify all randomized controlled trial (RCT) in MM up to July 2017 using a combination of text and MeSH terms.

SELECTION CRITERIA

Any randomized controlled trial (RCT) comparing bisphosphonates versus placebo/no treatment/bisphosphonates and observational studies or case reports examining bisphosphonate-related ONJ in patients with MM were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors extracted the data. Data were pooled and reported as hazard ratio (HR) or risk ratio (RR) using a random-effects model. We used meta-regression to explore statistical heterogeneity. Network meta-analysis using Bayesian approach was conducted.

MAIN RESULTS

In this update, we included four new studies (601 participants), resulting in a total of 24 included studies.Twenty RCTs compared bisphosphonates with either placebo or no treatment and four RCTs involved another bisphosphonate as a comparator. The 24 included RCTs enrolled 7293 participants. Pooled results showed that there was moderate-quality evidence of a reduction in mortality with on OS from 41% to 31%, but the confidence interval is consistent with a larger reduction and small increase in mortality compared with placebo or no treatment (HR 0.90, 95% CI 0.76 to 1.07; 14 studies; 2706 participants). There was substantial heterogeneity among the included RCTs (I² = 65%) for OS. To explain this heterogeneity we performed a meta-regression assessing the relationship between bisphosphonate potency and improvement in OS, which found an OS benefit with zoledronate but limited evidence of an effect on PFS. This provided a further rationale for performing a network meta-analyses of the various types of bisphosphonates that were not compared head-to-head in RCTs. Results from network meta-analyses showed evidence of a benefit for OS with zoledronate compared with etidronate (HR 0.56, 95% CI 0.29 to 0.87) and placebo (HR 0.67, 95% CI 0.46 to 0.91). However, there was no evidence for a difference between zoledronate and other bisphosphonates.The effect of bisphosphonates on disease progression (PFS) is uncertain. Based on the HR of 0.75 (95% CI 0.57 to 1.00; seven studies; 908 participants), 47% participants would experience disease progression without treatment compared with between 30% and 47% with bisphosphonates (low-quality evidence). There is probably a similar risk of non-vertebral fractures between treatment groups (RR 1.03, 95% CI 0.68 to 1.56; six studies; 1389 participants; moderate-quality evidence). Pooled analysis demonstrated evidence for a difference favoring bisphosphonates compared with placebo or no treatment on prevention of pathological vertebral fractures (RR 0.74, 95% CI 0.62 to 0.89; seven studies; 1116 participants; moderate-quality evidence) and skeletal-related events (SREs) (RR 0.74, 95% CI 0.63 to 0.88; 10 studies; 2141 participants; moderate-quality evidence). The evidence for less pain with bisphosphonates was of very low quality (RR 0.75, 95% CI 0.60 to 0.95; eight studies; 1281 participants).Bisphosphonates may increase ONJ compared with placebo but the confidence interval is very wide (RR 4.61, 95% CI 0.99 to 21.35; P = 0.05; six studies; 1284 participants; low-quality evidence). The results from the network meta-analysis did not show any evidence for a difference in the incidence of ONJ (eight RCTs, 3746 participants) between bisphosphonates. Data from nine observational studies (1400 participants) reported an incidence of 5% to 51% with combination of pamidronate and zoledronate, 3% to 11% with zoledronate alone, and 0% to 18% with pamidronate alone.The pooled results showed no evidence for a difference in increase in frequency of gastrointestinal symptoms with the use of bisphosphonates compared with placebo or no treatment (RR 1.23, 95% CI 0.95 to 1.59; seven studies; 1829 participants; low-quality evidence).The pooled results showed no evidence for a difference in increase in frequency of hypocalcemia with the use of bisphosphonates compared with placebo or no treatment (RR 2.19, 95% CI 0.49 to 9.74; three studies; 1090 participants; low-quality evidence). The results from network meta-analysis did not show any evidence for differences in the incidence of hypocalcemia, renal dysfunction and gastrointestinal toxicity between the bisphosphonates used.

AUTHORS' CONCLUSIONS

Use of bisphosphonates in participants with MM reduces pathological vertebral fractures, SREs and pain. Bisphosphonates were associated with an increased risk of developing ONJ. For every 1000 participants treated with bisphosphonates, about one patient will suffer from the ONJ. We found no evidence of superiority of any specific aminobisphosphonate (zoledronate, pamidronate or ibandronate) or non-aminobisphosphonate (etidronate or clodronate) for any outcome. However, zoledronate was found to be better than placebo and first-generation bisposphonate (etidronate) in pooled direct and indirect analyses for improving OS and other outcomes such as vertebral fractures. Direct head-to-head trials of the second-generation bisphosphonates are needed to settle the issue if zoledronate is truly the most efficacious bisphosphonate currently used in practice.

Evidence on the analgesic role of bisphosphonates and denosumab in the treatment of pain due to bone metastases: A systematic review within the European Association for Palliative Care guidelines project

BACKGROUND

Bisphosphonates and denosumab are well-established therapies to reduce the frequency and severity of skeletal-related events in patients with bone metastasis. However, the analgesic effect of these medications on bone pain is uncertain.

AIM

To identify, critically appraise and synthesize existing evidence to answer the following questions: 'In adult patients with metastatic bone pain, what is the evidence that bisphosphonates and denosumab are effective and safe in controlling pain?' and 'What is the most appropriate schedule of bisphosphonate/denosumab administration to control bone pain?'. This review also updates the 2002 Cochrane review 'Bisphosphonates for the relief of pain secondary to bone metastases'.

DESIGN

Standard systematic review and narrative synthesis.

DATA SOURCES

MEDLINE, EMBASE and Cochrane CENTRAL databases were searched for relevant articles published through 31 January 2014. A manual search was also performed. Study inclusion criteria were: a) conducted in adult patients; b) randomized controlled trial or meta-analisys; c) reported efficacy of bisphosphonates or denosumab on pain and/or decribed side effects versus placebo or other bisphosphonate; and d) English language.

RESULTS

The database search yielded 1585 studies, of which 43 (enrolling 8595 and 7590 patients, respectively, in bisphosphonate and denosumab trials) met the inclusion criteria. Twenty-two (79%) of the 28 placebo-controlled trials found no analgesic benefit for bisphosphonates. None of the denosumab studies assessed direct pain relief.

CONCLUSION

Evidence to support an analgesic role for bisphosphonates and denosumab is weak. Bisphosphonates and denosumab appear to be beneficial in preventing pain by delaying the onset of bone pain rather than by producing an analgesic effect per se.

Adjuvant bisphosphonate treatment in early breast cancer: meta-analyses of individual patient data from randomised trials

BACKGROUND

Bisphosphonates have profound effects on bone physiology, and could modify the process of metastasis. We undertook collaborative meta-analyses to clarify the risks and benefits of adjuvant bisphosphonate treatment in breast cancer.

METHODS

We sought individual patient data from all unconfounded trials in early breast cancer that randomised between bisphosphonate and control. Primary outcomes were recurrence, distant recurrence, and breast cancer mortality. Primary subgroup investigations were site of first distant recurrence (bone or other), menopausal status (postmenopausal [combining natural and artificial] or not), and bisphosphonate class (aminobisphosphonate [eg, zoledronic acid, ibandronate, pamidronate] or other [ie, clodronate]). Intention-to-treat log-rank methods yielded bisphosphonate versus control first-event rate ratios (RRs).

FINDINGS

We received data on 18,766 women (18,206 [97%] in trials of 2-5 years of bisphosphonate) with median follow-up 5·6 woman-years, 3453 first recurrences, and 2106 subsequent deaths. Overall, the reductions in recurrence (RR 0·94, 95% CI 0·87-1·01; 2p=0·08), distant recurrence (0·92, 0·85-0·99; 2p=0·03), and breast cancer mortality (0·91, 0·83-0·99; 2p=0·04) were of only borderline significance, but the reduction in bone recurrence was more definite (0·83, 0·73-0·94; 2p=0·004). Among premenopausal women, treatment had no apparent effect on any outcome, but among 11 767 postmenopausal women it produced highly significant reductions in recurrence (RR 0·86, 95% CI 0·78-0·94; 2p=0·002), distant recurrence (0·82, 0·74-0·92; 2p=0·0003), bone recurrence (0·72, 0·60-0·86; 2p=0·0002), and breast cancer mortality (0·82, 0·73-0·93; 2p=0·002). Even for bone recurrence, however, the heterogeneity of benefit was barely significant by menopausal status (2p=0·06 for trend with menopausal status) or age (2p=0·03), and it was non-significant by bisphosphonate class, treatment schedule, oestrogen receptor status, nodes, tumour grade, or concomitant chemotherapy. No differences were seen in non-breast cancer mortality. Bone fractures were reduced (RR 0·85, 95% CI 0·75-0·97; 2p=0·02).

INTERPRETATION

Adjuvant bisphosphonates reduce the rate of breast cancer recurrence in the bone and improve breast cancer survival, but there is definite benefit only in women who were postmenopausal when treatment began.

FUNDING

Cancer Research UK, Medical Research Council.

Bone disease in multiple myeloma: pathophysiology and management

Myeloma bone disease (MBD) is a devastating complication of multiple myeloma (MM). More than 80% of MM patients suffer from destructive bony lesions, leading to pain, fractures, mobility issues, and neurological deficits. MBD is not only a main cause of disability and morbidity in MM patients but also increases the cost of management. Bone destruction and lack of bone formation are main factors in the development of MBD. Some novel factors are found to be involved in the pathogenesis of MBD, eg, receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG) system (RANKL/OPG), Wingless (Wnt), dickkopf-1 (Wnt/DKK1) pathway. The addition of novel agents in the treatment of MM, use of bisphosphonates and other supportive modalities such as radiotherapy, vertebroplasty/kyphoplasty, and surgical interventions, all have significant roles in the treatment of MBD. This review provides an overview on the pathophysiology and management of MBD.

International Myeloma Working Group recommendations for the treatment of multiple myeloma-related bone disease

PURPOSE

The aim of the International Myeloma Working Group was to develop practice recommendations for the management of multiple myeloma (MM) -related bone disease.

METHODOLOGY

An interdisciplinary panel of clinical experts on MM and myeloma bone disease developed recommendations based on published data through August 2012. Expert consensus was used to propose additional recommendations in situations where there were insufficient published data. Levels of evidence and grades of recommendations were assigned and approved by panel members.

RECOMMENDATIONS

Bisphosphonates (BPs) should be considered in all patients with MM receiving first-line antimyeloma therapy, regardless of presence of osteolytic bone lesions on conventional radiography. However, it is unknown if BPs offer any advantage in patients with no bone disease assessed by magnetic resonance imaging or positron emission tomography/computed tomography. Intravenous (IV) zoledronic acid (ZOL) or pamidronate (PAM) is recommended for preventing skeletal-related events in patients with MM. ZOL is preferred over oral clodronate in newly diagnosed patients with MM because of its potential antimyeloma effects and survival benefits. BPs should be administered every 3 to 4 weeks IV during initial therapy. ZOL or PAM should be continued in patients with active disease and should be resumed after disease relapse, if discontinued in patients achieving complete or very good partial response. BPs are well tolerated, but preventive strategies must be instituted to avoid renal toxicity or osteonecrosis of the jaw. Kyphoplasty should be considered for symptomatic vertebral compression fractures. Low-dose radiation therapy can be used for palliation of uncontrolled pain, impending pathologic fracture, or spinal cord compression. Orthopedic consultation should be sought for long-bone fractures, spinal cord compression, and vertebral column instability.

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

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

What is the evidence for the use of bisphosphonate therapy in newly diagnosed multiple myeloma patients lacking bone disease?

A 55-year-old man without prior medical problems presented to the emergency room with a 2-month history of progressive fatigue. Initial workup showed a hemoglobin level of 9.0 g/dL and an increased total protein level of 12.6 g/dL. Further testing revealed a normal serum calcium and creatinine, an IgG kappa paraprotein of 5.4 g/dL, and a Bence Jones proteinuria of 450 mg of kappa light chain in 24 hours. The bone marrow showed 60% plasma cells with normal cytogenetics and t(4;14), but no other associated genetic abnormalities by FISH. Skeletal survey and MRI of the spine were negative for myeloma bone disease. The patient's oncologist recently began therapy with lenalidomide, bortezomib, and dexamethasone and recommended the initiation of zoledronic acid monthly. The patient questions the benefit of this drug because he has no bone disease.

Bisphosphonates in multiple myeloma: a network meta-analysis

BACKGROUND

Bisphosphonates are specific inhibitors of osteoclastic activity and used in the treatment of patients with multiple myeloma (MM). While bisphosphonates are shown to be effective in reducing vertebral fractures and pain, their role in improving overall survival (OS) remains unclear. This is an update of a Cochrane review first published in 2002 and previously updated in 2010.

OBJECTIVES

To assess the evidence related to benefits and harms associated with use of various types of bisphosphonates (aminobisphosphonates versus nonamino bisphosphonates) in the management of patients with MM. Our primary objective was to determine whether adding bisphosphonates to standard therapy in MM improves OS and progression-free survival (PFS), and decreases skeletal-related morbidity. Our secondary objectives were to determine the effects of bisphosphonates on pain, quality of life, incidence of hypercalcemia, incidence of bisphosphonate-related gastrointestinal toxicities, osteonecrosis of jaw and hypocalcemia.

SEARCH METHODS

We searched MEDLINE, LILACS, EMBASE (December 2009 to October 2011) and the Cochrane Controlled Trials Register (all years, latest Issue September 2011) to identify all randomized trials in MM up to October 2011 using a combination of text and MeSH terms. We also handsearched relevant meeting proceedings (December 2009 to October 2011).

SELECTION CRITERIA

Any randomized controlled trial (RCT) assessing the role of bisphosphonates and observational studies or case reports examining bisphosphonate-related osteonecrosis of the jaw in patients with MM were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors extracted the data. Data were pooled and reported as hazard ratio (HR) or risk ratio (RR) under a random-effects model. Statistical heterogeneity was explored using metaregression.

MAIN RESULTS

In this update, we included 2 studies (2464 patients) that were not part of our last Cochrane review published in 2010. In this review we included 16 RCTs comparing bisphosphonates with either placebo or no treatment and 4 RCTs with a different bisphosphonate as a comparator. The 20 included RCTs enrolled 6692 patients. Overall methodological quality of reporting was moderate. Thirty per cent (6/20) of trials reported the method of generating the randomization sequence. Forty per cent (8/20) of trials had adequate allocation concealment. Withdrawals and dropouts were described in 60% (12/20) of trials. Pooled results showed no direct effect of bisphosphonates on OS compared with placebo or no treatment (HR 0.96, 95% CI 0.82 to 1.13; P = 0.64). However, there was a statistically significant heterogeneity among the included RCTs (I(2) = 55%, P = 0.01) for OS. To explain this heterogeneity we performed a metaregression assessing the relationship between bisphosphonate potency and improvement in OS, which found indicating an OS benefit with zoledronate (P = 0.058). This provided a further rationale for performing network meta-analyses of the various types of bisphosphonates that were not compared head to head in RCTs. Results from network meta-analyses showed superior OS with zoledronate compared with etidronate (HR 0.43, 95% CI 0.16 to 0.86) and placebo (HR 0.61, 95% CI 0.28 to 0.98). However, there was no difference between zoledronate and other bisphosphonates. Pooled analysis did not demonstrate a beneficial effect of bisphosphonates compared with placebo or no treatment in improving PFS (HR 0.70, 95% CI 0.41 to 1.19; P = 0.18) There was no heterogeneity among trials reporting PFS estimates (I(2) = 35%, P = 0.20).Pooled analysis demonstrated a beneficial effect of bisphosphonates compared with placebo or no treatment on prevention of pathological vertebral fractures (RR 0.74, 95% CI 0.62 to 0.89; I(2) = 7%), skeletal-related events (SRE) (RR 0.80, 95% CI 0.72 to 0.89; I(2) = 2%) and amelioration of pain (RR 0.75, 95% CI 0.60 to 0.95; I(2) = 63%). The network meta-analysis did not show any difference in the incidence of osteonecrosis of the jaw (5 RCTs, 3198 patients) between bisphosphonates. Rates of osteonecrosis of the jaw in observational studies (9 studies, 1400 patients) ranged from 0% to 51%. The pooled results (6 RCTs, 1689 patients) showed no statistically significant increase in frequency of gastrointestinal symptoms with the use of bisphosphonates compared with placebo or no treatment (RR 1.23, 95% CI 0.95 to 1.60; P = 0.11).The pooled results (3 RCTs, 1002 patients) showed no statistically significant increase in frequency of hypocalcemia with the use of bisphosphonates compared with placebo or no treatment (RR 2.19, 95% CI 0.49 to 9.74). The network meta-analysis did not show any differences in the incidence of hypocalcemia, renal dysfunction and gastrointestinal toxicity between the bisphosphonates used.

AUTHORS' CONCLUSIONS

Use of bisphosphonates in patients with MM reduces pathological vertebral fractures, SREs and pain. Assuming a baseline risk of 20% to 50% for vertebral fracture without treatment, between 8 and 20 MM patients should be treated to prevent vertebral fracture(s) in one patient. Assuming a baseline risk of 31% to 76% for pain amelioration without treatment, between 5 and 13 MM patients should be treated to reduce pain in one patient. With a baseline risk of 35% to 86% for SREs without treatment, between 6 and 15 MM patients should be treated to prevent SRE(s) in one patient. Overall, there were no significant adverse effects associated with the administration of bisphosphonates identified in the included RCTs. We found no evidence of superiority of any specific aminobisphosphonate (zoledronate, pamidronate or ibandronate) or nonaminobisphosphonate (etidronate or clodronate) for any outcome. However, zoledronate appears to be superior to placebo and etidronate in improving OS.

Advances in the biology and treatment of bone disease in multiple myeloma

Osteolytic bone disease is pathognomonic of multiple myeloma (MM) and affects more than 80% of patients. Bone disease results in skeletal-related events (SRE) such as vertebral compression fractures, which may cause cord compression, hypercalcemia, pathologic fractures that require radiation or surgical fixation, and severe pain. All of these not only result in a negative impact on quality of life but also adversely impact overall survival. Osteolytic disease is a consequence of increased osteoclast (OC) activation along with osteoblast (OB) inhibition, resulting in altered bone remodeling. OC number and activity are increased in MM via cytokine deregulation within the bone marrow (BM) milieu, whereas negative regulators of OB differentiation suppress bone formation. Bisphosphonates are a well-established treatment of myeloma-related skeletal disease and are the current standard of care. However, complications arising from their long-term use have prompted studies of schedule optimization and alternate strategies. Several novel agents are currently under investigation for their positive effect on bone remodeling via OC inhibition. The identification of negative regulators of OB differentiation has prompted the use of anabolic agents. In addition to restoring bone remodeling, these drugs may inhibit tumor growth in vivo. Future studies will look to combine or sequence all of these agents with the goal of not only alleviating morbidity from bone disease but also capitalizing on the resultant antitumor activity.

Established role of bisphosphonate therapy for prevention of skeletal complications from myeloma bone disease

Patients with advanced multiple myeloma (MM) often have increased osteolytic activity of osteoclasts and impaired osteogenesis by osteoblasts, resulting in osteolytic bone lesions that increase the risk of skeletal-related events (SREs) including pathologic fracture, the need for radiotherapy or surgery to bone, and spinal cord compression. Such SREs are potentially life-limiting, and can reduce patients' functional independence and quality of life. Bisphosphonates (e.g., oral clodronate and intravenous pamidronate and zoledronic acid) can inhibit osteoclast-mediated osteolysis, thereby reducing the risk of SREs, ameliorating bone pain, and potentially prolonging survival in patients with MM. Extensive clinical experience demonstrates that bisphosphonates are generally well tolerated, and common adverse events are typically mild and manageable. Studies are ongoing to optimize the timing and duration of bisphosphonate therapy in patients with bone lesions from MM.

Emerging therapies in metastatic bone pain

INTRODUCTION

Current treatment for metastatic bone pain is mainly palliative. Recent insights into the molecular mechanisms involved in bone metastases have led to the identification of promising therapeutic targets. This review offers an update of preclinical and clinical data on new drugs for metastatic bone pain.

AREAS COVERED

Biphosphonates are the gold standard of bone-targeted therapy in bone metastases, for their anti-resorptive and analgesic effects. New drugs aim at breaking the 'vicious cycle' of bone metastatic disease, due to the bidirectional interaction between cancer cells and bone microenvironment. Osteoprotegerin, RANK/RANKL interaction, cathepsin K, the Wnt/beta-catenin pathway and sclerostin are emerging targets for modulation of cancer-induced bone desorption. Other promising targets are those expressed in cancer cells that metastasize to bone, including Src, nerve growth factor, endothelin A, TGF-beta and CXCR4. Interesting therapeutic options include targets on nociceptors that innervate the bone, such as TPRV1, Trk and cannabinoid receptors.

EXPERT OPINION

Emerging therapies promise, in the next 10 years, a significant expansion in the array of therapeutic options for bone metastases. Most of these drugs are still in an early phase of development. Further clinical trials are needed to support the evidence of their efficacy and tolerability profile.

Supportive therapy in multiple myeloma

In this chapter we want to give an overview on various supportive measures, which help to prevent or to fight complications of multiple myeloma, improve patient wellbeing and increase safety of administration of specific anti-myeloma therapy.

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.

Pathogenesis and management of myeloma bone disease

Osteolytic bone disease is a frequent complication of multiple myeloma, resulting in skeletal complications that are a significant cause of morbidity and mortality. It is the result of increased activity of osteoclasts that is not followed by reactive bone formation by osteoblasts. Recent studies have revealed novel molecules and pathways that are implicated in osteoclast activation and osteoblast inhibition, including the RANKL/osteoprotegerin pathway, macrophage inflammatory proteins and the wingless type signaling pathway. These molecules also appear to interfere with tumor growth and survival, providing possible targets for the development of novel drugs for the management of lytic disease in myeloma. Currently, bisphosphonates are the mainstay of treatment for myeloma bone disease, although several novel agents appear promising. This review focuses on recent advances in understanding the biology of bone disease in multiple myeloma, diagnosis and recent progress in treatment options.

Advances in imaging and the management of myeloma bone disease

Osteolytic disease is a major complication of multiple myeloma that may lead to devastating skeletal-related events (SREs). Conventional radiography remains the gold standard for the evaluation of bone disease in patients with myeloma. However, whole-body magnetic resonance imaging (MRI) is recommended in patients with normal conventional radiography and should be performed as part of staging in all patients with a solitary plasmacytoma of bone. Urgent MRI is also the diagnostic procedure of choice to assess suspected cord compression, whereas computed tomography can guide tissue biopsy. Positron emission tomography with computed tomography can provide complementary information to MRI, but its use in multiple myeloma must be better defined by further studies. The incorporation of abnormal MRI findings into the definition of symptomatic myeloma also needs to be clarified. Bisphosphonates remain the cornerstone for the management of myeloma bone disease. Intravenous pamidronate and zoledronic acid are equally effective in reducing SREs, whereas zoledronic acid seems to offer survival benefits in symptomatic patients. Caution is needed to avoid adverse events, such as renal impairment and osteonecrosis of the jaw. Novel antiresorptive agents, such as denosumab, have given encouraging results, but further studies are needed before their approval for managing myeloma bone disease. Combination approaches with novel antimyeloma agents, such as bortezomib (which has anabolic effects on bone) with bisphosphonates or with drugs that enhance osteoblast function, such as antidickkopf-1 agents, antisclerostin drugs, or sotatercept, may favorably alter our way of managing myeloma bone disease in the near future.

Bones, breasts, and bisphosphonates: rationale for the use of zoledronic acid in advanced and early breast cancer

Bisphosphonates inhibit osteoclast-mediated bone resorption, thereby inhibiting the release of growth factors necessary to promote cancer cell growth, differentiation, and tumor formation in bone. These agents have demonstrated efficacy for delaying the onset and reducing the incidence of skeletal-related events in the advanced breast cancer setting, and have been shown to prevent cancer therapy-induced bone loss in the early breast cancer setting. Emerging clinical data indicate that the role of bisphosphonates in advanced and early breast cancer is evolving. Retrospective analyses and recent clinical trial data show that zoledronic acid may improve outcomes in some patients with breast cancer. Data from ABCSG-12 and ZO-FAST suggest that zoledronic acid may improve disease-free survival in the adjuvant breast cancer setting in postmenopausal women or women with endocrine therapy-induced menopause, and recent data from a predefined subset of the AZURE trial added to the anticancer story. However, the overall negative AZURE trial also raises questions about the role of bisphosphonates as an anticancer agent in patients with breast cancer. Overall, these data suggest that the addition of zoledronic acid to established anticancer regimens may have potential anticancer benefits in specific patient populations, although more studies are required to define its role.

Improving progression-free and overall survival in patients with cancer: a potential role for bisphosphonates

INTRODUCTION

Bisphosphonates are a well-established therapy for patients with multiple myeloma or bone metastases from advanced cancers and are used routinely to delay the onset and reduce the risk of skeletal-related events. Emerging evidence indicates that they also may provide additional anticancer benefits. These developments warrant reappraisal of their role in patients with cancer and reevaluation of optimal therapeutic regimens.

AREAS COVERED

This article reviews the evidence of the anticancer activity of bisphosphonates in patients with solid tumors or multiple myeloma. The underlying mechanisms of the anticancer activity of bisphosphonates are elucidated from preclinical and translational data that show that bisphosphonates suppress tumor growth and survival, inhibit tumor-mediated angiogenesis, or stimulate host anticancer immune response. These data also provide insights into the potential for therapeutic combinations. Preclinical and clinical data relating to the anticancer effects of bisphosphonates are reviewed by cancer type.

EXPERT OPINION

Future trials of bisphosphonates in cancer patients will explore the underlying mechanism of the anticancer benefit in greater detail and attempt to examine critically the potential clinical benefit in individual cancer types in early/advanced disease.

Therapeutic options in the management of myeloma bone disease

Advanced multiple myeloma is typically accompanied by osteolytic bone lesions resulting from heightened osteolytic activity of osteoclasts and decreased rates of osteogenesis by osteoblasts. Therefore, patients with myeloma bone disease are at increased risk for skeletal-related events (SREs) such as pathologic fracture, the need for radiotherapy or surgery to bone, spinal cord compression, and hypercalcemia of malignancy. Each of these can reduce patients' functional independence, quality of life, and survival. Radiotherapy and surgery are often used to palliate bone pain and to stabilize, repair, or prevent bone fractures. Bisphosphonates (BPs) may reduce the risk of SREs. In particular, clodronate, pamidronate, and zoledronic acid (ZOL) have demonstrated efficacy for delaying the onset of potentially life-threatening SREs. Overall, BPs have a well established tolerability profile. The introduction of BPs for multiple myeloma was practice-changing, and patients now experience far fewer serious fractures and hypercalcemia of malignancy. Ongoing studies will help further refine and optimize the timing and duration of BP therapy in patients with myeloma bone disease.

Bisphosphonates in multiple myeloma

BACKGROUND

Bisphosphonates are specific inhibitors of osteoclastic activity and are currently used as supportive therapy for multiple myeloma (MM). However, the exact clinical role of bisphosphonates in MM remains unclear.

OBJECTIVES

This update of the first review published in 2002. We have also analyzed observational studies targeting osteonecrosis of jaw (ONJ).

SEARCH STRATEGY

We searched the literature using the methods outlined in the previous review. We also searched observational studies or case reports examining ONJ.

SELECTION CRITERIA

We selected RCTs with a parallel design related to the use of bisphosphonate in myeloma. We also selected observational studies or case reports examining bisphosphonates related to ONJ.

DATA COLLECTION AND ANALYSIS

We have reported pooled data using either hazard ratio or risk ratio and, when appropriate, as absolute risk reduction and the number needed to treat to prevent or to cause a pathological event. We have assessed statistical heterogeneity and reported I(2) statistic.

MAIN RESULTS

This review includes 17 trials with 1520 patients analyzed in bisphosphonates groups, and 1490 analyzed in control groups. In comparison with placebo/no treatment, the pooled analysis demonstrated the beneficial effect of bisphosphonates on prevention of pathological vertebral fractures (RR= 0.74 (95% CI: 0.62 to 0.89), P = 0.001), total skeletal related events (SREs) (RR= 0.80 (95% CI: 0.72 to 0.89), P < 0.0001) and on amelioration of pain (RR = 0.75 (95% CI: 0.60 to 0.95), P = 0.01). We found no significant effect of bisphosphonates on overall survival (OS), progression-free survival (PFS), hypercalcemia or on the reduction of non-vertebral fractures. The indirect meta-analyses did not find the superiority of any particular type of bisphosphonate over others. Only two RCTs reported ONJ. The identified observational studies suggested that ONJ may be a common event (range: 0% to 51%).

AUTHORS' CONCLUSIONS

Adding bisphosphonates to the treatment of MM reduces pathological vertebral fractures, SREs and pain but not mortality. Assuming the baseline risk of 20% to 50% for vertebral fracture without treatment, we estimate that between eight and 20 MM patients should be treated to prevent vertebral fracture(s) in one patient. Assuming the baseline risk of 31% to 76% for pain amelioration without treatment, we estimate that between five to 13 MM patients should be treated to reduce pain in one patient. Also, with the baseline risk of 35% to 86% for SREs without treatment, we estimate that between six and 15 MM patients should be treated to prevent SRE(s) in one patient. No bisphoshphonate appears to be superior to others.

Efficacy of clodronate, pamidronate, and zoledronate in reducing morbidity and mortality in cancer patients with bone metastasis: a meta-analysis of randomized clinical trials

BACKGROUND

Complications from skeletal-related events (SREs) constitute a challenge in the care of patients with metastatic bone disease (MBD) that originated from any type of malignancy.

OBJECTIVE

The purpose of this article was to compare the efficacy of clodronate, pamidronate, and zoledronate with that of placebo in reducing morbidity and overall mortality in cancer patients with MBD.

METHODS

MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched (from inception to January 2009) to retrieve randomized clinical trials that evaluated the bisphosphonates of interest. The search included articles published in English, French, Italian, Portugese, and Spanish. Patients with a definite (ie, biopsy-proven) diagnosis of MBD were included in the analysis. We extracted and combined data from studies that reported the number of patients with SREs and mortality data. A random-effects, meta-analytic model was applied in all calculations. The Jadad scale was used to assess the quality of study reporting.

RESULTS

The literature search identified 62 potential full-text studies; 44 of these studies were excluded and 18 were evaluated. The mean (SD) quality of reporting of the included studies was 57.8% (22.6%), or 2.89/5 (1.1/5). Each of the 3 drugs was found to be more effective than placebo in preventing all SREs in cancer patients with MBD. The relative risk of developing SREs was 0.70 (95% CI, 0.61-0.81; N = 1211) for zoledronate, 0.81 (95% CI, 0.73-0.91; N = 2251) for pamidronate, and 0.87 (95% CI, 0.75-1.00; N = 681) for clodronate. However, no clear advantage of one drug over the others was observed (CIs overlapped substantially). None of the bisphosphonates was more beneficial than placebo in reducing the number of deaths in the course of the trials (P = NS).

CONCLUSION

Clodronate, pamidronate, and zoled-ronate were associated with reductions in morbidity in cancer patients with MBD with regard to preventing SREs, but were not associated with a reduction in overall mortality.

Ideal body weight correlates better with engraftment after PBSC autograft than actual body weight, but is under-estimated in myeloma patients possibly due to disease-related height loss

Stem cell dose is important in determining rate of engraftment following autograft. We show closer correlation with haematopoietic reconstitution when the CD34+ cell dose is calculated using ideal (IBW) rather than actual (ABW) body weight in 218 patients receiving peripheral blood stem cell (PBSC) autograft for haematological malignancy. ABW was 21% greater than IBW thus the median CD34+ dose of 5.0 x 10(6)/kg (ABW) rose to 6.1 x 10(6)/kg when calculated by IBW. Neutrophils reached 0.5 x 10(9)/l in 11 days (range 8-21), while platelets reached 20 x 10(9)/l unsupported in 12 days (range 7-38). For both neutrophil and platelet engraftment, a greater inverse correlation was seen when IBW was used to calculate stem cell dose (r2=0.082 vs r2=0.104 for neutrophils and r2=0.085 vs r2=0.135 for platelets). Those non-myeloma patients who failed to achieve a CD34+ dose of 4 x 10(6) cells/kg by ABW but did so by IBW achieved neutrophil and platelet engraftment not significantly different from those who achieved that stem cell dose by both methods. This was not confirmed in patients treated for myeloma, possibly owing to inaccurate IBW in patients with skeletal height loss. We confirm that calculation of CD34+ cell dose by IBW safely predicts engraftment for patients with haematological malignancies other than myeloma undergoing PBSC autograft.

The effect of novel anti-myeloma agents on bone metabolism of patients with multiple myeloma

Immunomodulatory drugs (IMiDs) and bortezomib have been recently used in the management of patients with both newly diagnosed and relapsed/refractory multiple myeloma. Except of their direct anti-myeloma effect, these agents also alter the interactions between myeloma cells and marrow microenvironment. Several recent studies have investigated their potential effect on myeloma bone disease. Preclinical studies have demonstrated that IMiDs reduce osteoclast formation and function in vitro. Clinical studies have confirmed that thalidomide reduces markers of bone resorption, while lenalidomide induces osteoclast arrest in myeloma patients. However, IMiDs seem to have no effect on osteoblast exhaustion present in myeloma. The proteasome inhibitor bortezomib restores abnormal bone remodeling through the inhibition of osteoclast function and the increase in osteoblast differentiation and activity in vitro. In myeloma patients, bortezomib reduces biochemical markers of bone resorption and normalizes the RANKL/osteoprotegerin ratio, while at the same time increases bone formation markers reducing levels of dickkopf-1 protein. Whether these effects are direct and not only a consequence of the agents' antimyeloma activity is not totally clear. This review summarizes all available data for these attractive agents that combine potent anti-myeloma activity with beneficial effects on bone and may alter the way of management of myeloma-related bone disease.

Treatment for Myeloma Bone Disease: Table 1

Multiple myeloma (MM) is a B cell malignancy characterized by enhanced bone loss commonly associated with diffuse osteopenia, focal lytic lesions, pathologic fractures, hypercalcemia, and bony pain. Bone destruction in MM results from asynchronous bone turnover wherein increased osteoclastic bone resorption is not accompanied by a comparable increase in bone formation. Consequently, patients with MM frequently require radiation therapy, surgery, and analgesic medications. The recent development of minimally invasive surgical procedures such as kyphoplasty allows patients with myeloma with vertebral compression fractures to have immediate improvement in their quality of life with shorter hospital stays. Bisphosphonates are specific inhibitors of osteoclastic activity, and these agents have been evaluated in patients with MM with bone disease during the past 15 years. Monthly i.v. infusions of either pamidronate or zoledronic acid have reduced the skeletal complications among patients with MM and are now a mainstay of myeloma therapy. Orally administered bisphosphonates, in contrast, have shown little ability to slow the development of skeletal complications in these patients. Although preclinical studies suggest that nitrogen-containing bisphosphonates have potent antitumor effects, clinical trials will be necessary, probably at higher doses given more slowly, to establish their possible antitumor effects clinically. Moreover, recent advances in the use of bone-seeking radiopharmaceuticals make these attractive therapeutic candidates to combine with bisphosphonates or radiosensitizing drugs (e.g., bortezomib) to achieve a synergistic effect. As our understanding of the pathophysiology of myeloma bone disease continues to grow, new target therapies will continue to emerge, offering new and more advanced options for the management of myeloma bone disease.

Jaw avascular osteonecrosis after treatment of multiple myeloma with zoledronate

PURPOSE

Multiple myeloma, the second most common haematopoietic cancer, which represents the collection of plasma-cell neoplasms that invariably becomes fatal when self-renewing myeloma cells begin unrestrained proliferation. The major clinical manifestation of multiple myeloma is related to the loss of bone through osteolysis. This can lead to pathologic fractures, spinal cord compression, hypercalcaemia, and pain. It is also a major cause of morbidity and mortality in these patients, who frequently require radiation therapy, surgery and analgesic medications. Bisphosphonates are specific inhibitors of osteoclastic activity, and are currently used to prevent bone complications and to treat malignant hypercalcaemia in patients with multiple myeloma, or bone metastases from breast and prostate cancers. Hence, osteonecrosis of the mandible has been reported in three patients from Centro Hospitalar de Vila Nova de Gaia (CHVNG) with multiple myeloma treated for over 18-48 months with intravenous zoledronate, commonly prescribed for multiple myeloma therapy. Although, this report alerts clinicians about the potential complication of bone necrosis in patients receiving bisphosphonate therapy, many questions remain concerning the underlying pathogenesis of this process.

PATIENTS AND METHODS

The medical and dental records of three patients with multiple myeloma, who were treated in CHVNG in the past 4 years, were reviewed. These three patients presented exposed bone and osteonecrosis of the mandible, and shared one common clinical feature: all of them were treated with bisphosphonate zoledronate, administered intravenously for long periods. Sequential orthopantomograms (OPGs) and histological evaluation have been analysed from the biopsies of the non healing dental extraction sites of these patients.

RESULTS

After a routine dental extraction, these patients developed avascular osteonecrosis of the mandible and secondary bone infection with Actinomyces israelii (actinomycotic osteomyelitis), with no evidence of metastatic disease evaluated by biopsy. In these three described clinical cases, surgical debridment without flap elevation, intensive antibiotherapy and the suspension of the zoledronate treatment allowed a partial recovery of the patients. The purpose of this clinical report is to point out that patients suffering from multiple myeloma can develop bone osteonecrosis induced by treatment with bisphosphonates. Research to determine the mechanism of this dental phenomenon is needed to fully validate and substantiate the possible link between bisphosphonate treatment of multiple myeloma or other cancer diseases and avascular osteonecrosis of the jaws. Until then, clinicians involved in the care of patients at risk should consider this possible complication.

Myeloma bone disease and treatment options

Multiple myeloma (MM) is a B-cell malignancy characterized by enhanced bone loss commonly associated with a diffuse osteopenia, focal lytic lesions, pathologic fractures, hypercalcemia, and bony pain. Bone destruction in MM results from asynchronous bone turnover wherein increased osteoclastic bone resorption is not accompanied by a comparable increase in bone formation. Recent characterization of osteoclast-activating factors (OAFs), receptor activator of nuclear factor-kappaB (RANK) ligand (RANKL)-osteoprotegerin-RANK system, and inhibitors of Wnt signaling have provided a better understanding of myeloma bone disease in molecular level. The development of minimally invasive surgical procedures such as kyphoplasty and vertebroplasty allows myeloma patients with vertebral compression fractures to have immediate improvement in quality of life and shorter hospital stays. Monthly intravenous infusion of either pamidronate or zoledronic acid have reduced the skeletal complications among MM patients and are now a mainstay of myeloma therapy. Orally administered bisphosphonates, in contrast, have shown little ability to slow the development of skeletal complications in these patients. Although pre-clinical studies suggest nitrogen-containing bisphosphonates have potent anti-tumor effects, clinical trials will be necessary, probably at higher doses given more slowly, to establish their possible anti-tumor effects clinically. As our understanding of the pathophysiology of myeloma bone disease continues to increase, new target therapies will continue to emerge offering new and more advanced options for the management of myeloma bone disease.

Advances in the management of myeloma bone disease

Multiple myeloma is the second most common adult haematological malignancy. One of the major clinical features is the development of a unique osteolytic bone disease, characterised by progressive and devastating bone destruction, bone pain, pathological fractures and hypercalcaemia. Bisphosphonates, inhibitors of osteoclastic bone resorption, are the standard therapy for myeloma-induced bone disease. However, as our understanding of the molecular mechanisms involved in the development of myeloma bone disease increases, new molecular targets have been identified for the treatment of this devastating bone disease.

Myeloma bone disease

The major clinical manifestation of multiple myeloma is related to the osteolytic bone destruction. The bone disease can lead to pathologic fractures, spinal cord compression, hypercalcemia, and pain. It is also a major cause of morbidity and mortality in these patients. These patients frequently require radiation therapy, surgery and analgesic medications. Bisphosphonates are specific inhibitors of osteoclastic activity, and these agents have been evaluated in myeloma patients with bone disease during the past 15 years. Several large randomized trials have been conducted in myeloma patients also receiving chemotherapy. Orally administered bisphosphonates have shown little ability to slow the development of skeletal complications in these patients. In contrast, more potent intravenous monthly infusions of either pamidronate or zoledronic acid have reduced the skeletal complications among these patients and are now a mainstay of myeloma therapy. A number of other types of new anti-bone-resorptive agents are also in early clinical development.

Treatment of multiple myeloma

Conventional chemotherapies are no longer the only treatment in multiple myelomatosis. High-dose chemotherapy and autologous transplantation are not curative but do increase relapse-free survival time in young patients. Thalidomide is efficacious in refractory and relapsing myeloma and its evaluation is going on. Curative and preventive treatments of skeletal events, infections and anemia improve quality of life. All together, these strategies imply therapeutic knowledge and choices but allow an about 5-year-long median survival time in modern studies. Treatment options for myeloma now include, not only conventional chemotherapy regimens, but also novel symptomatic drugs and strategies that increase survival and/or quality of life, although they fail to provide a cure. In parallel with this expansion of the treatment armamentarium, physicians must acquire the knowledge needed to select the best treatment for the individual patient. After reviewing the rationale, effectiveness, and safety of each of these treatments, we will discuss the indications that we believe are legitimate.

Management of multiple myeloma: a systematic review and critical appraisal of published studies

We have done a systematic review of all randomised studies in myeloma, identified through a comprehensive search. Our aim was to investigate and critically examine the effects of various treatment modalities on outcome in patients with multiple myeloma and address 22 specific clinical questions in the management of this disease. As a result of our analysis we identified two therapeutic advances in the management of myeloma that, according to the evidence, are most important for improving outcome. These advances were: introduction of high dose chemotherapy, which appears to be superior to conventional chemotherapy, and the use of bisphosphonates, which decrease the probability of pathological vertebral fractures. However, the overall quality of the body of evidence for myeloma management was poor. Many trials were done with small sample sizes, and did not include reporting power analysis. The majority of studies had inadequate allocation concealment, and few were analysed according to intention to treat principle. We conclude that the quality of total evidence supporting treatment recommendations in myeloma is modest at best and has an ample scope for improvement.

Aetiology of bone disease and the role of bisphosphonates in multiple myeloma

Osteolytic bone disease is a major cause of morbidity in patients with multiple myeloma. Our understanding of the pathophysiology of multiple myeloma has increased substantially during the past decade. However the underlying mechanisms of bone destruction and the treatments available have, until recently, received relatively little specific attention. In this review, we provide an overview of the RANK/RANKL/osteoprotegerin system; we describe its interaction with other cellular mechanisms, through which malignant plasma cells drive osteolysis, and explain how bisphosphonates can be used to block this action. We also review the supporting evidence for bisphosphonates as the treatment of choice for patients with bone complications related to multiple myeloma, and discuss possible developments for targeted therapy in the future.

Zoledronic acid treatment of 5T2MM-bearing mice inhibits the development of myeloma bone disease: evidence for decreased osteolysis, tumor burden and angiogenesis, and increased survival

Multiple myeloma is characterized by the growth of plasma cells in the bone marrow and the development of osteolytic bone disease. Myeloma cells are found closely associated with bone, and targeting this environment may therefore affect both the bone disease and the growth of myeloma cells. We have investigated the effect of the potent bisphosphonate, zoledronic acid, on the development of bone disease, tumor burden, and disease-free survival in the 5T2MM model of myeloma. 5T2MM murine myeloma cells were injected intravenously into C57BL/KaLwRij mice. After 8 weeks, all animals had a paraprotein. Animals were treated with zoledronic acid (120 microg/kg, subcutaneously, twice weekly) or vehicle, from the time of tumor cell injection or from paraprotein detection for 12 or 4 weeks, respectively. All animals injected with tumor cells developed osteolytic lesions, a decrease in cancellous bone volume, an increase in osteoclast perimeter, and a decrease in bone mineral density. Zoledronic acid prevented the formation of lesions, prevented cancellous bone loss and loss of bone mineral density, and reduced osteoclast perimeter. Zoledronic acid also decreased paraprotein concentration, decreased tumor burden, and reduced angiogenesis. In separate experiments, Kaplan-Meier analysis demonstrated a significant increase in survival after treatment with zoledronic acid when compared with control (47 vs. 35 days). A single dose of zoledronic acid was also shown to be effective in preventing the development of osteolytic bone disease. These data show that zoledronic acid is able to prevent the development of osteolytic bone disease, decrease tumor burden in bone, and increase survival in a model of established myeloma.

Bisphosphonates and osteoprotegerin as inhibitors of myeloma bone disease

BACKGROUND

A major clinical feature in multiple myeloma is the development of osteolytic bone disease. The increase in bone destruction is due to uncontrolled osteoclastic bone resorption. Until recently the factors responsible for mediating the increase in osteoclast formation in myeloma have been unclear. However, recent studies have implicated a number of factors, including the ligand for receptor activator of NFkappaB (RANKL) and macrophage inflammatory protein-1alpha. The demonstration that increased osteoclastic activity plays a central role in this process and the identification of molecules that may play a critical role in the development of myeloma bone disease have resulted in studies aimed at identifying new approaches to treating this aspect of myeloma.

METHODS

Studies have been performed to determine the ability of recombinant osteoprotegerin (Fc.OPG), a soluble decoy receptor for RANKL, and potent new bisphosphonates to inhibit the development of myeloma bone disease in the 5T2MM murine model of multiple myeloma.

RESULTS

Fc.OPG was shown to prevent the development of osteolytic bone lesions in 5T2MM bearing animals. These changes were associated with a preservation of the cancellous bone loss induced by myeloma cells and an inhibition of osteoclast formation. Bisphosphonates, including ibandronate and zoledronic acid, were also shown to inhibit the development of osteolytic bone lesions in the 5T2MM model and alternative models of myeloma bone disease.

CONCLUSIONS

Bisphosphonates and Fc.OPG are effective inhibitors of the development of osteolytic bone lesions in pre-clinical murine models of myeloma bone disease.

Comparison of five biochemical markers of bone resorption in multiple myeloma: elevated pre-treatment levels of S-ICTP and U-Ntx are predictive for early progression of the bone disease during standard chemotherapy

Increased osteoclastic bone resorption is the major causal factor of bone disease in multiple myeloma. Recently, non-invasive methods have been developed for the estimation of bone resorptive activity. To evaluate the biological sensitivity and clinical usefulness of five biochemical assays for measuring the C-terminal telopeptide of collagen I (ICTP) in serum (beta-Crosslaps ELISA and ICTP radioimmunoassay) and urinary creatinine-adjusted excretions of pyridinoline (PYR), deoxypyridinoline (DPD) and N-terminal telopeptide of collagen I (Ntx), we performed a study of 34 consecutive newly diagnosed myeloma patients. Serum and morning-fasting, second-void urine samples were taken before the start of treatment. In total, 40 age- and sex-adjusted healthy individuals served as controls. Results were expressed as Z-scores. All test variables were highly significantly elevated in the patients (P < 0.001). Serum (S)-ICTP was elevated (Z-score > 2) in most patients (85%) and showed significantly higher Z-score values than the other markers. S-ICTP remained more sensitive than the urinary assays when patients with impaired renal function were excluded from analysis. S-ICTP and the urinary metabolites correlated significantly with skeletal morbidity. S-beta-Crosslaps correlated with the bone morbidity only when patients with renal insufficiency were excluded from the analysis. High levels of S-ICTP and urinary (U)-Ntx correlated with an increased risk for early progression of bone lesions during standard melphalan-prednisolone treatment. U-Ntx and S-ICTP are sensitive tools for estimating the increased bone resorption in multiple myeloma and are clinically useful for identifying patients with increased risk of early progression of bone disease.

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.