American Society of Clinical Oncology clinical practice guidelines: the role of bisphosphonates in multiple myeloma.

PURPOSE: To determine clinical practice guidelines for the use of bisphosphonates in the prevention and treatment of lytic bone disease in multiple myeloma and to determine their respective role relative to other conventional therapies for this condition. METHODS: An expert multidisciplinary Panel reviewed pertinent information from the published literature through January 2002. Values for levels of evidence and grade of recommendation were assigned by expert reviewers and approved by the Panel. Expert consensus was used if there were insufficient published data. The Panel addressed which patients to treat and when to treat them in the course of their disease. Additionally, specific drug delivery issues, duration of therapy, initiation of treatment and management of treatment of lytic bone disease was reviewed and compared with other forms of therapy for lytic bone lesions. Finally, the Panel discussed patient and physician expectations associated with this therapy for bony metastases, as well as public policy implications related to the use of bisphosphonates. The guidelines underwent external review by selected physicians, by the Health Services Research Committee members, and by the ASCO Board of Directors. RESULTS: The available evidence involving randomized controlled trials is modest but supports that oral clodronate, intravenous pamidronate, and intravenous zoledronic acid are superior to placebo in reducing skeletal complications. A reduction in vertebral fractures has consistently been seen across all studies. No agent has shown a definitive survival benefit. Intravenous zoledronic acid has recently been shown to be as effective as intravenous pamidronate. Because there are no direct comparisons between clodronate and pamidronate or zoledronic acid, the superiority of one agent cannot be definitively established. However, the panel recommends only intravenous pamidronate or zoledronic acid in light of the use of the time to first skeletal event as the primary end point and more complete assessment of bony complications in studies evaluating it. Additionally, clodronate is not available in the United States. The choice between pamidronate and zoledronic acid will depend on choosing between the higher drug cost of zoledronic acid, with its shorter, more convenient infusion time (15 minutes), versus the less expensive drug, pamidronate, with its longer infusion time (2 hours). CONCLUSION: Bisphosphonates provide a meaningful supportive benefit to multiple myeloma patients with lytic bone disease. However, further research on bisphosphonates is warranted, including the following: (1) when to start and stop therapy, (2) how to integrate their use with other treatments for lytic bone disease, (3) how to evaluate their role in myeloma patients without lytic bone involvement, (4) how to distinguish between symptomatic and asymptomatic bony events, and (5) how to better determine their cost-benefit consequence.     

Safety of intravenous and oral bisphosphonates and compliance with dosing regimens

Patients with advanced cancers--particularly breast and prostate cancers--are at high risk for bone metastasis, leading to accelerated bone resorption and clinically significant skeletal morbidity. Bisphosphonates are effective inhibitors of bone resorption and reduce the risk of skeletal complications in patients with bone metastases. The standard routes of administration for bisphosphonates used in clinical practice are either oral or i.v. infusion. Oral administration of bisphosphonates is complicated by poor bioavailability (generally <5%) and poor gastrointestinal tolerability. First-generation bisphosphonates, such as clodronate (Bonefos; Anthra Pharmaceuticals; Princeton, NJ), must be administered at high oral doses (1,600-3,200 mg/day) to achieve therapeutic effects, which leads to poor tolerability and compliance with oral dosing regimens. Infusion of bisphosphonates is associated with dose- and infusion-rate-dependent effects on renal function. In particular, high bisphosphonate doses (e.g., 1,500 mg clodronate) can cause severe renal toxicity unless infused slowly over many hours. In contrast, the newer, more potent bisphosphonates effectively inhibit bone resorption at micromolar concentrations, and the small doses required can be administered via relatively short i.v. infusions without adversely affecting renal function. Zoledronic acid (Zometa; Novartis Pharmaceuticals Corp.; East Hanover, NJ) is a new generation bisphosphonate, and the recommended dose of 4 mg can be safely infused over 15 minutes. The 90-mg dose of pamidronate (Aredia; Novartis Pharmaceuticals Corp.) and the 6-mg dose of ibandronate (Bondronat; Hoffmann-La Roche Inc.; Nutley, NJ) require 1- to 4-hour infusions. Intravenous bisphosphonates require less frequent dosing (once a month) and are generally well tolerated with long-term use in patients with bone metastases. Zoledronic acid has demonstrated the broadest clinical activity in patients with bone metastases.     

Management of Metastatic Bone Disease and Hypercalcemia of Malignancy

Thirty years of research have established bisphosphonates as the most effective agents for the inhibition of osteoclast-mediated bone resorption, and they play an important role in the management of malignant bone disease. Bisphosphonates have been systematically improved through chemical engineering, and the newest nitrogen-containing compounds, including zoledronic acid and ibandronate, are 1000-fold more potent than first-generation compounds. Consequently, they can be administered at low molar doses via short intravenous infusions without compromising renal safety. Bisphosphonates have a variety of metabolic effects on osteoclasts. Nitrogen-containing bisphosphonates inhibit protein prenylation via the mevalonate pathway, thereby inhibiting osteoclast activation and inducing apoptosis. Preclinical studies suggest that bisphosphonates also have direct and indirect antitumor activity. In animal models, bisphosphonates reduced skeletal tumor burden and bone metastases. Currently, intravenous bisphosphonates are the standard therapy for hypercalcemia of malignancy, and they have become an integral part of the treatment of bone metastases in conjunction with standard antineoplastic agents. Intravenous bisphosphonates quickly normalize serum calcium, reduce skeletal complications, and palliate bone pain in patients with bone metastases. Intravenous pamidronate (90mg via 2-hour infusion every 3–4 weeks) has, until recently, been the international standard for the treatment of osteolytic bone lesions from breast cancer or multiple myeloma. However, 4mg zoledronic acid (via 15-minute infusion) is quickly becoming the new standard based on evidence that it is as safe and effective as 90mg pamidronate in patients with breast cancer and multiple myeloma and significantly more effective for hypercalcemia of malignancy. Consequently, the American Society of Clinical Oncology guidelines for breast cancer and multiple myeloma recommend pamidronate or zoledronic acid for patients with radiographic evidence of osteolytic bone destruction. Moreover, 4mg zoledronic acid is the only bisphosphonate that has demonstrated significant clinical benefit in patients with other solid tumors, including lung cancer, and prostate cancer patients with primarily osteoblastic bone metastases. Bisphosphonates also may have activity in the adjuvant setting to prevent or delay the development of bone metastases. Studies with oral clodronate in early breast cancer have provided clinical evidence that bone metastases can be inhibited, and the studies are ongoing with more potent bisphosphonates. Bisphosphonates have also been shown to prevent cancer treatment-induced bone loss. These and other studies continue to redefine the role of bisphosphonates in the treatment of malignant bone disease and the management of bone health in cancer patients.     

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.     

Metastatic Bone Disease

The cancer patient with skeletal metastases now has a much improved range of treatment options with major advances in bone-specific drug therapy as well as radiotherapy and radiopharmaceuticals, orthopaedic surgery, and systemic anticancer therapy with cytotoxic and endocrine agents. Recent advances in the understanding of bone remodeling mechanisms and the interdependence of cancer cells and bone have been closely associated with development of the bisphosphonate drugs and newer agents such as osteoprotegerin (OPG). The bisphosphonates are potent inhibitors of osteoclast mediated bone resorption and appear to function either by induction of apoptosis in mature osteoclasts or by inhibition of formation of osteoclasts from progenitor cells. Bisphosphonates are the treatment of choice in tumor-induced hypercalcemia. Bisphosphonates have a clear role in reducing bone pain and skeletal complications, such as pathological fracture and are being evaluated in the prevention of bone metastases. Until recently, intravenous (IV) pamidronate has been the drug most commonly prescribed for oncological indications and oral clodronate has also been widely used in some countries outside the US. However, newer and more potent drugs, such as zoledronate, are increasingly having a major impact on routine therapy. Three of the largest ever bisphosphonate trials, using zoledronate in metastatic bone disease have recently been completed. In a breast and multiple myeloma trial in 1648 patients, zoledronate (4mg IV) was shown to be equivalent to pamidronate (90mg IV) in reducing skeletal events and was more convenient to administer. In trials in prostate cancer and a wide range of other solid tumor types affecting bone, both the number of patients with skeletal-related events and the rate of bone complications were reduced. The indications for bisphosphonates are, therefore, no longer constrained by tumor type. The assessment of response to therapy is a vital part of management of metastatic bone disease. Plain radiographs and the isotope bone scan remain widely used but have many limitations. Newer imaging techniques such as computerized tomography, magnetic resonance imaging, and positron emission tomography may be useful in selected situations. Recent research suggests that measurement of tumor markers and bone-specific markers will play an increasingly important role in assessment of response. In particular, bone resorption markers measuring collagen breakdown have potential as rapid, convenient, and inexpensive measures of response, with suppression of bone resorption into the normal range being an important aim of bone-specific treatments.     

Pharmacokinetic and clinical equivalence of oral and intravenous ibandronate for metastatic bone disease

While monthly infusions of intravenous (i.v.) bisphosphonates effectively reduce skeletal complications of metastatic bone disease, regular hospital visits are inconvenient for patients and may reduce their quality of life. Daily oral bisphosphonate therapy would allow long-term patient management in the community setting. However, the use of oral bisphosphonate therapy (e.g. oral clodronate) is limited in clinical practice, due to its relatively low efficacy in comparison with i.v. agents, poor gastrointestinal tolerability, and a large tablet size that is difficult for patients to administer. Ibandronate is a highly potent, third-generation aminobisphosphonate that has been developed in an oral formulation with a small, easy-to-swallow tablet and convenient once-daily dosing. Pharmacokinetic evaluations of oral ibandronate have shown a linear dose-dependent increase in plasma concentrations that is non-saturable, and is proportional to its effect on bone-resorption markers. This ensures predictability of response to a given oral dose of ibandronate, reducing safety concerns. Bioavailability analysis suggests that oral ibandronate (50 mg) taken once daily, 30 min before food, provides comparable bone-surface exposure to i.v. ibandronate (6 mg) infused every 3–4 weeks i.e. the two formulations are dose-equivalent. The clinical equivalence of oral ibandronate (50 mg) and i.v. ibandronate (6 mg) is indicated by comparable reductions in the relative risk of skeletal events in phase III trials of patients with bone metastases from breast cancer.     

Bisphosphonates--mechanisms of action in multiple myeloma

Bisphosphonates are a class of anti-resorptive drugs, which are effective in the treatment of osteoclast-mediated bone disease, including the osteolytic bone disease, which is a major clinical feature of patients with multiple myeloma. Recently, increases in survival following treatment with pamidronate have been observed in some patients with multiple myeloma, raising the possibility that bisphosphonates may also have an anti-tumour effect. We have demonstrated that bisphosphonates can have an anti-tumour effect in human myeloma cell in vitro, and that these anti-tumour effects induced by potent nitrogen-containing bisphosphonates are a result of inhibition of enzymes of the mevalonate pathway. However, we and others have been unable to demonstrate an anti-tumour effect of the potent bisphosphonate ibandronate in vivo, using murine models of multiple myeloma. It is therefore likely that only by studying patients receiving bisphosphonates will we be able to determine whether these compounds have a clinically important anti-tumour effect.     

Bisphosphonates: biological response modifiers in breast cancer

Bone recurrence constitutes one third of initial sites of relapse and one half of distant sites of relapse at 10 years from diagnosis of breast cancer. Bone pain, fracture (including vertebral fracture resulting from increased bone resorption following chemotherapy-induced menopause), and hypercalcemia are components of skeletal morbidity. The pathophysiology of malignant osteopathy occurs because of the secretion of substances (such as parathyroid hormone-related peptide), by the malignant cell, which stimulate osteoclast function; this in turn feeds further growth, which causes a vicious cycle. Interruption of this cycle by bisphosphonates may inhibit the growth of malignant cells. Bisphosphonates are drugs that inhibit bone turnover by decreasing bone resorption. Side effects of bisphosphonates include upper gastrointestinal symptoms (in oral nitrogen-containing bisphosphonates) and diarrhea (in oral non-nitrogen-containing bisphosphonates) and an acute phase-like reaction with intravenous (I.V.) pamidronate. Bisphosphonates have different molecular mechanisms of action: Nitrogen-containing bisphosphonates (eg, pamidronate and alendronate) inhibit the mevalonate-signaling pathway while the non-nitrogen-containing drugs (eg, clodronate) incorporate into adenosine triphosphate analogues. There is in vitro evidence that these drugs also possess anticancer properties. In hypercalcemia patients, treatment with pamidronate and zoledronate produce prompt and efficient normocalcemia. Intravenous pamidronate and zoledronate, oral clodronate, and ibandronate reduce skeletal complications in patients with bone metastases; I.V. pamidronate and clodronate are useful for bone pain relief. Three adjuvant bisphosphonate trials are discussed herein: 2 small open-label studies giving conflicting results and a large placebo-controlled trial of oral clodronate. This latter trial shows a reduction in the incidence of skeletal metastases (while the patients are on therapy) and an improved survival at 5 years.     

Treatment of breast cancer with bone metastasis: bisphosphonate treatment — current and future

There are a variety of treatments for patients with bone metastases from breast cancer. These include bisphosphonates, antitumor endocrine and cytotoxic systemic therapies, radiotherapy to the metastatic site, radionucleotides, and conservative treatment (analgesics). The optimal combination treatment for bone metastases is not clear. Bisphosphonates are effective for reducing skeletal complications such as bone pain, pathological fracture, bone surgery, and hypercalcemia. Bisphosphonates are recommended as the gold standard therapy for breast cancer with bone metastases. Treatment guidelines tend to recommend starting a bisphosphonate at the time of diagnosis of bone metastases. Animal models have supported the prevention of bone metastasis by bisphosphonate therapy, but three major adjuvant clinical trials of the oral bisphosphonate clodronate have yielded conflicting results. However, our preliminary trial of an intravenous bisphosphonate, pamidronate, showed effective inhibition of bone metastases. The use of bisphosphonates, especially zoledronic acid, as adjuvant therapy is promising, but it is still investigational.     

Osteonecrosis of the jaw in cancer after treatment with bisphosphonates: incidence and risk factors.

PURPOSE: Osteonecrosis of the jaw (ONJ) has been associated recently with the use of pamidronate and zoledronic acid. We studied the incidence, characteristics, and risk factors for the development of ONJ among patients treated with bisphosphonates for bone metastases. PATIENTS AND METHODS: ONJ was assessed prospectively since July 2003. The first bisphosphonate treatment among patients with ONJ was administered in 1997. Two hundred fifty-two patients who received bisphosphonates since January 1997 were included in this analysis. RESULTS: Seventeen patients (6.7%) developed ONJ: 11 of 111 (9.9%) with multiple myeloma, two of 70 (2.9%) with breast cancer, three of 46 (6.5%) with prostate cancer, and one of 25 (4%) with other neoplasms (P = .289). The median number of treatment cycles and time of exposure to bisphosphonates were 35 infusions and 39.3 months for patients with ONJ compared with 15 infusions (P < .001) and 19 months (P = .001), respectively, for patients with no ONJ. The incidence of ONJ increased with time to exposure from 1.5% among patients treated for 4 to 12 months to 7.7% for treatment of 37 to 48 months. The cumulative hazard was significantly higher with zoledronic acid compared with pamidronate alone or pamidronate and zoledronic acid sequentially (P < .001). All but two patients with ONJ had a history of dental procedures within the last year or use of dentures. CONCLUSION: The use of bisphosphonates seems to be associated with the development of ONJ. Length of exposure seems to be the most important risk factor for this complication. The type of bisphosphonate may play a role and previous dental procedures may be a precipitating factor.     

Prevention of bone metastases from breast cancer by adjuvant bisphosphonate therapy

There is increasing evidence regarding the importance of osteoclast activation in the pathogenesis of bone metastases. Cancer cells produce osteoclast-activating factors which play an important role in the development of bone metastases. Bisphosphonates are drugs that inhibit bone turnover by decreasing bone resorption. In patients with bone metastases from breast cancer, the effectiveness of bisphosphonate is well established for reducing skeletal complications, such as bone pain, pathological fracture, bone surgery and hypercalcemia. Recent attention has focused on a possible preventive effect on bisphosphonates of bone metastases. Animal models have supported the prevention of bone metastasis by bishosphonate therapy, but three major adjuvant clinical trials of the oral bisphosphonate clodronate have yielded conflicting results. However, our preliminary trial of intravenous bisphosphonate with pamidronate showed effective inhibition of bone metastases. Use of bisphosphonates as adjuvant therapy is still investigational yet promising. Several more randomized trials are underway to further investigate adjuvant therapy with bisphosphonates.     

Clinical efficacy of bisphosphonate therapy for bone metastasis from breast cancer

Bisphosphonates inhibit osteoclastic bone resorption and are being used as treatment for bone metastases from breast cancer. Intravenous bisphosphonate therapy can significantly reduce skeletal related events (SREs) when administered concurrently with chemotherapy or endocrine therapy. In addition, intravenous bisphosphonate monotherapy is also able to alleviate cancer induced bone pain, and to improve bone metastases in some patients. Oral bisphosphonates are not routinely used for the treatment of bone metastases due to their low bioavailability. However, minodronate, a bisphosphonate 100-fold more potent than pamidronate, is now in phase II clinical studies in Japan, and may alter the role of oral bisphosphonates in the treatment of bone metastasis from breast cancer. The ASCO guidelines recommend that patients with osteolytic bone metastases be treated not with bisphosphonate monotherapy, but with concurrent bisphosphonate and systemic therapy. In addition, it is also recommended that current standards of care for cancer pain, analgesics and radiotherapy, should not be replaced with bisphosphonate therapy.     

Safety and convenience of a 15-minute infusion of zoledronic acid

Skeletal morbidity, including hypercalcemia of malignancy (HCM), places a severe burden on patients with advanced cancers. Bisphosphonates effectively correct HCM and reduce skeletal morbidity in patients with bone metastases. However, with the widespread use of bisphosphonates, the safety and convenience of therapy are emerging concerns. The delivery of effective doses of early bisphosphonates required a lengthy 24-hour i.v. infusion protocol because of renal tolerability issues. The introduction of more potent bisphosphonates with superior tolerability profiles has allowed therapy to be safely delivered via shorter i.v. infusions. Intravenous therapy with etidronate, clodronate, pamidronate, ibandronate, and zoledronic acid has been used to treat HCM and skeletal complications in cancer patients. Of these therapies, zoledronic acid (which can be safely administered via a 15-minute i.v. infusion) is the most convenient and effective and has demonstrated an excellent safety profile with long-term use. Zoledronic acid has also received the broadest regulatory approval of any bisphosphonate and can be used to treat HCM or bone lesions secondary to multiple myeloma and a wide variety of solid tumors, including breast, prostate, and lung cancers. In addition to the patient preference for shorter infusion times, the 15-minute i.v. infusion protocol of zoledronic acid can provide benefits for infusion centers by potentially increasing patient throughput.     

Markers of bone resorption in patients treated with pamidronate

Pyridinoline (PYD), deoxypyridinoline (DPD), and N-telopeptide (NTX) are markers of bone resorption. In cancer patients with bone metastases, NTX is more often elevated than either of the pyridinolines. Bisphosphonates inhibit osteoclasts and their treatment decreases skeletal complications of malignancy. The aim of this study was to correlate urinary PYD, DPD, and NTX levels with clinical events in patients receiving pamidronate. 25 cancer patients with lytic bone disease were treated with monthly pamidronate combined with endocrine or chemotherapy; 27 others were on placebo. Twenty-four hour urines were collected at baseline, 1, 3 and 6 months. NTX values were determined by enzyme-linked immunosorbent assay (ELISA); PYD and DPD values were determined by reverse phase high performance liquid chromatography (HPLC). Two hour urines were also collected weekly for 21 patients. The greatest difference as a result of pamidronate treatment was observed in NTX values. Maximum suppression was achieved 2 weeks after treatment. Of the 25 patients who received pamidronate, 21 had initially elevated NTX values. 12 of the 21 finished with normal NTX values, whilst 9/21 had NTX values which remained abnormally elevated. The proportions of patients with fractures between these two subgroups approached statistical significance (P = 0.07) while the proportions with bony disease progression were significant (P = 0.03, Fisher's exact test). Measuring NTX levels appears useful in monitoring bisphosphonate therapy of bone metastases. The goal of treatment should be to normalise NTX excretion.     

American Society of Clinical Oncology guideline on the role of bisphosphonates in breast cancer. American Society of Clinical Oncology Bisphosphonates Expert Panel.

PURPOSE: To determine clinical practice guidelines for the use of bisphosphonates in the prevention and treatment of bone metastases in breast cancer and their role relative to other therapies for this condition. METHODS: An expert multidisciplinary panel reviewed pertinent information from the published literature and meeting abstracts through May 1999. Additional data collected as part of randomized trials and submitted to the United States Food and Drug Administration were also reviewed, and investigators were contacted for more recent information. Values for levels of evidence and grade of recommendation were assigned by expert reviewers and approved by the panel. Expert consensus was used if there were insufficient published data. The panel addressed which patients to treat and when in their course of disease, specific drug delivery issues, duration of therapy, management of bony metastases with other therapies, and the public policy implications. The guideline underwent external review by selected physicians, members of the American Society of Clinical Oncology (ASCO) Health Services Research Committee, and the ASCO Board of Directors. RESULTS: Bisphosphonates have not had an impact on the most reliable cancer end point: overall survival. The benefits have been reductions in skeletal complications, ie, pathologic fractures, surgery for fracture or impending fracture, radiation, spinal cord compression, and hypercalcemia. Intravenous (IV) pamidronate 90 mg delivered over 1 to 2 hours every 3 to 4 weeks is recommended in patients with metastatic breast cancer who have imaging evidence of lytic destruction of bone and who are concurrently receiving systemic therapy with hormonal therapy or chemotherapy. For women with only an abnormal bone scan but without bony destruction by imaging studies or localized pain, there is insufficient evidence to suggest starting bisphosphonates. Starting bisphosphonates in patients without evidence of bony metastasis, even in the presence of other extraskeletal metastases, is not recommended. Studies of bisphosphonates in the adjuvant setting have yielded inconsistent results. Starting bisphosphonates in patients at any stage of their nonosseous disease, outside of clinical trials, despite a high risk for future bone metastasis, is currently not recommended. Oral bisphosphonates are one of several options which can be used for preservation of bone density in premenopausal patients with treatment-induced menopause. The panel suggests that, once initiated, IV bisphosphonates be continued until evidence of substantial decline in a patient's general performance status. The panel stresses that clinical judgment must guide what is a substantial decline. There is no evidence addressing the consequences of stopping bisphosphonates after one or more adverse skeletal events. Symptoms in the spine, pelvis, or femur require careful evaluation for spinal cord compression and pathologic fracture before bisphosphonate use and if symptoms recur, persist, or worsen during therapy. The panel recommends that current standards of care for cancer pain, analgesics and local radiation therapy, not be displaced by bisphosphonates. IV pamidronate is recommended in women with pain caused by osteolytic metastasis to relieve pain when used concurrently with systemic chemotherapy and/or hormonal therapy, since it was associated with a modest pain control benefit in controlled trials. CONCLUSION: Bisphosphonates provide a meaningful supportive but not life-prolonging benefit to many patients with bone metastases from cancer. Further research is warranted to identify clinical predictors of when to start and stop therapy, to integrate their use with other treatments for bone metastases, to identify their role in the adjuvant setting in preventing bone metastases, and to better determine their cost-benefit consequences.     

Bone complications in multiple myeloma

Multiple myeloma is the malignant proliferation of plasma cells involving more than 10% of the bone marrow. The bone complications associated with multiple myeloma include bone pain, pathologic fractures, hypercalcemia of malignancy and cord compressions. The principal pathophysiology of bone disease in multiple myeloma is a shift in the balance of bone remodeling toward bone resorption. In recent years, bisphosphonates have become an important treatment for the bone complications of multiple myeloma. Potent inhibitors of osteoclast activity, bisphosphonates interfere with biochemical pathways and induce osteoclast apoptosis. Bisphosphonates also antagonize osteoclastogenesis and promote differentiation of osteoblasts, as well as inhibiting other aspects of osteoclast homeostasis and metabolism. Several studies have evaluated treatment with bisphosphonates in patients with multiple myeloma, and have demonstrated the efficacy of clodronate (Bonefos; Anthra Pharmaceuticals; Princeton, NJ; www.bonefos.com), pamidronate (Aredia; Novartis Pharmaceuticals Corp; East Hanover, NJ; www.pamidronate.com) and zoledronic acid (Zometa; Novartis Pharmaceuticals Corp; East Hanover, NJ; www.us.zometa.com) in reduction of pain, reduction of SREs and survival. Moreover, recent data suggest direct and indirect antimyeloma activity of pamidronate and zoledronic acid.     

Adverse effects of bisphosphonates: current issues

Four bisphosphonates are used for the treatment of metastatic bone disease: clodronate, which is available outside the United States in both intravenous and oral formulations; intravenous pamidronate; intravenous zoledronic acid; and ibandronate, which is also available in intravenous and oral forms. Since the use of bisphosphonates in patients with cancer is palliative, their impact on patients' quality of life and their adverse-effect profiles are essential considerations for effective patient management. The most common adverse effects associated with bisphosphonates are renal toxicity, acute-phase reactions, gastrointestinal (GI) toxicity, and osteonecrosis of the jaw (ONJ). The incidence of these adverse events varies significantly between bisphosphonates. Renal toxicity is a potentially life-threatening event reported in studies of zoledronic acid and, to a lesser extent, pamidronate. In contrast, the renal safety profile of intravenous ibandronate and oral bisphosphonates is similar to that of placebo. Acute-phase reactions occur only with intravenous aminobisphosphonates and may be more common with zoledronic acid. Gastrointestinal effects occur only with oral agents (clodronate and ibandronate) and may be avoided by adhering to dosing instructions. More recently, ONJ has recently emerged as a complication of bisphosphonate use. However, its true incidence is not yet known. The potential adverse effects of bisphosphonates should be considered in the context of the individual patient's characteristics and preferences when selecting a bisphosphonate for metastatic bone disease.     

A phase II trial evaluating the palliative benefit of second-line oral ibandronate in breast cancer patients with either a skeletal related event (SRE) or progressive bone metastases (BM) despite standard bisphosphonate (BP) therapy

Background Despite bisphosphonate treatment, most patients with metastatic breast cancer will have either progressive bone metastases or skeletal related events (SREs). We evaluated the impact of second-line ibandronate on pain control and markers of bone turnover in these patients. Methods Patients with either an SRE or bony progression while on clodronate or intravenous (IV) pamidronate were switched to oral ibandronate 50 mg daily for 12 weeks. Pain scores and urinary N-telopeptide were evaluated weekly for 4 weeks and at weeks 8 and 12. There was no change in systemic anti-cancer treatment in the month before or after commencing study treatment. Palliative response was defined as a ≥ two-unit reduction in the worst pain score. Patient preferences between IV and oral bisphosphonate therapy were assessed. Results Thirty women completed the study. By week 12, patients experienced a significant improvement in pain control (OR = 0.41; P = 0.028) with 12 of 26 (46.2%) evaluable patients achieving a palliative response. Of the 23 patients who had received first-line IV pamidronate, 20 of 23 (87.0%) preferred oral therapy. Conclusion Patients with either progressive bone metastases or SREs while on clodronate or pamidronate may experience significant pain palliation with a switch to a more potent bisphosphonate. If confirmed by randomized trials, clinicians can start moving away from the paradigm whereby patients remain on a single bisphosphonate regimen throughout the course of their disease.     

Optimizing clinical benefits of bisphosphonates in cancer patients with bone metastases

Bisphosphonates are important treatments for bone metastases. Considerations for optimizing the clinical benefits of bisphosphonates include efficacy, compliance, and safety. Several bisphosphonates are approved for clinical use; however, few have demonstrated broad efficacy in the oncology setting and been compared directly in clinical trials. Among patients with bone metastases from breast cancer, the efficacy of approved bisphosphonates was evaluated in a Cochrane review, showing a reduction in the risk of skeletal-related events (SREs) ranging from 8% to 41% compared with placebo. Between-trial comparisons are confounded by inconsistencies in trial design, SRE definition, and endpoint selection. Zoledronic acid has demonstrated clinical benefits beyond those of pamidronate in a head-to-head trial that included patients with breast cancer or multiple myeloma. Compliance and adherence also have effects on treatment efficacy. In a comparison study, the adherence rates with oral bisphosphonates were found to be significantly lower compared with those of intravenous bisphosphonates. The safety profiles of oral and intravenous bisphosphonates differ. Oral bisphosphonates are associated with gastrointestinal side effects, whereas intravenous bisphosphonates have dose- and infusion rate-dependent effects on renal function. Osteonecrosis of the jaw is an uncommon but serious event in patients receiving monthly intravenous bisphosphonates or denosumab. The incidence of this event can be reduced with careful oral hygiene. A positive benefit-risk ratio for bisphosphonates has been established, and ongoing clinical trials will determine whether individualized therapy is possible.     

Optimising treatment of bone metastases by Aredia™ and Zometa™

Metastatic bone disease develops as a result of the many interactions between tumour cells and bone cells. This leads to disruption of normal bone metabolism, with the increased osteoclast activity seen in most, if not all, tumor types providing a rational target for treatment. The clinical course of metastatic bone disease in multiple myeloma, breast and prostate cancers is relatively long, with patients experiencing sequential skeletal complications over a period of several years. These include bone pain, fractures, hypercalcaemia, and spinal cord compression, all of which may profoundly impair a patient's quality of life. External beam radiotherapy and systemic endocrine and cytotoxic treatments are the mainstay of treatment in advanced cancers. However, it is now clear that the bisphosphonates provide an additional treatment strategy, which reduces both the symptoms and complications of bone involvement. Pamidronate (Aredia(TM)) is the most widely evaluated bisphosphonate and is recommended for most patients with multiple myeloma or breast cancer with bone metastases. Current research aims include the evaluation of new potent bisphosphonates such as zoledronic acid (Zometa(TM)). It is hoped that this compound is not only more convenient and easier to administer but also more effective in inhibiting skeletal morbidity. Zometa may also have some direct anticancer activity. Preclinical studies with Zometa have demonstrated its potential in malignant bone disease. Clinical studies in treatment of hypercalcemia of malignancy have been completed, as have Phase I and II trials in patients with cancer and pre-existing bone metastases. Three randomized, double-blind, controlled Phase III trials are now ongoing to establish the efficacy and safety of Zometa in treatment of bone metastases in patients with osteolytic and osteoblastic lesions. Additionally, new specific molecules such as osteoprotogerin have been developed that are based on our improved understanding of the cellular signalling mechanisms involved in cancer induced bone disease. These potent molecules are now entering clinical trials. Ongoing research is aimed at trying to define the optimum route, dose, schedule and type of bisphosphonate in metastatic bone disease and their use in the prevention and treatment of osteoporosis in cancer patients. In vitro suggestions of direct anti-cancer activity and some promising clinical data in early breast cancer have resulted in considerable interest in the possible adjuvant use of bisphosphonates to inhibit the development of bone metastases.