Bisphosphonates: clinical experience

Bone is a preferred site of metastasis for many solid tumors, and the complications associated with bone metastases can result in significant skeletal morbidity including severe bone pain, pathologic fracture, spinal cord compression, and hypercalcemia of malignancy (HCM). Bisphosphonates are the current standard of care for preventing skeletal complications associated with bone metastases. Clinical trials investigating the benefit of bisphosphonate therapy have used a composite end point defined as a skeletal-related event (SRE) or bone event, which typically includes pathologic fracture, spinal cord compression, radiation or surgery to bone, and HCM. Bisphosphonates have been shown to significantly reduce the incidence of these events in patients with bone metastases. Zoledronic acid (Zometa; Novartis Pharmaceuticals Corp.; East Hanover, NJ), pamidronate (Aredia; Novartis Pharmaceuticals Corp.), clodronate (Bonefos; Anthra Pharmaceuticals; Princeton, NJ), and ibandronate (Bondronat; Hoffmann-La Roche Inc.; Nutley, NJ) all have demonstrated efficacy superior to that of placebo in patients with breast cancer. Zoledronic acid is the only bisphosphonate that has been compared directly with pamidronate, and it was shown by multiple event analysis to be significantly more effective at reducing the risk of an SRE. In patients with prostate cancer, clodronate, etidronate (Didronel; Procter and Gamble Pharmaceuticals, Inc.; Cincinnati, OH), and pamidronate have demonstrated transient palliation of bone pain. However, zoledronic acid is the only bisphosphonate to demonstrate both significant and sustained pain reduction and a significantly lower incidence and longer time to onset of SREs compared with placebo. Zoledronic acid is also the only bisphosphonate to demonstrate efficacy in patients with bone metastases from a variety of other solid tumors, including lung cancer and renal cell carcinoma. In conclusion, bisphosphonates effectively reduce skeletal complications in patients with bone metastases from breast cancer, and zoledronic acid has demonstrated the broadest clinical activity in patients with a wide variety of tumor types.     

Toward new horizons: the future of bisphosphonate therapy

Bisphosphonate therapy has become a standard of care for patients with malignant bone disease. In addition, preclinical and preliminary clinical data suggest that bisphosphonates may prevent cancer-treatment-induced bone loss (CTIBL) and the development of malignant bone disease in patients with early-stage cancer. Patients who receive adjuvant hormonal therapy for breast cancer or androgen-deprivation therapy for prostate cancer are at an especially high risk for CTIBL because of reduced estrogenic signaling. Oral clodronate (Bonefos; Anthra Pharmaceuticals; Princeton, NJ), oral risedronate (Actonel; Proctor and Gamble Pharmaceuticals, Inc.; Cincinnati, OH), and i.v. zoledronic acid (Zometa; Novartis Pharmaceuticals Corp.; East Hanover, NJ) have all demonstrated promise in preventing CTIBL in patients receiving hormonal therapy for breast cancer. Zoledronic acid has demonstrated efficacy with the longest between-treatment interval (3-6 months) and is currently being investigated in the Zometa/Femara Adjuvant Synergy Trials (Z-FAST and ZO-FAST in the United States and Europe, respectively). In patients receiving androgen-deprivation therapy for prostate cancer, i.v. pamidronate (Aredia; Novartis Pharmaceuticals Corp.) and i.v. zoledronic acid both have demonstrated significant benefits over placebo, but only zoledronic acid produced significant increases in bone mineral density compared with baseline values. Additionally, bisphosphonates have demonstrated antitumor activities in preclinical models, and clinical trials with oral clodronate suggest that bisphosphonates might prevent or delay bone metastasis in patients with early-stage breast cancer. Clinical trials are investigating the effect of zoledronic acid on disease progression in patients with breast cancer, prostate cancer, and non-small cell lung cancer. The results of these clinical trials should further define the clinical benefit of bisphosphonates in the oncology setting.     

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.     

Bisphosphonates: preclinical review

Bisphosphonates effectively inhibit osteoclast-mediated bone resorption and are integral in the treatment of benign and malignant bone diseases. The evolution of bisphosphonates over the past 30 years has led to the development of nitrogen-containing bisphosphonates (N-BPs), which have a mechanism of action different from that of the nonnitrogen-containing bisphosphonates. Studies conducted over the past decade have elucidated the mechanism of action and pharmacologic properties of the N-BPs. N-BPs exert their effects on osteoclasts and tumor cells by inhibiting a key enzyme in the mevalonate pathway, farnesyl diphosphate synthase, thus preventing protein prenylation and activation of intracellular signaling proteins such as Ras. Recent evidence suggests that N-BPs also induce production of a unique adenosine triphosphate analogue (Apppi) that can directly induce apoptosis. Our increased understanding of the pharmacologic effects of bisphosphonates is shedding light on the mechanisms by which they exert antitumor effects. As a result of their biochemical effects on protein prenylation, N-BPs induce caspase-dependent apoptosis, inhibit matrix metalloproteinase activity, and downregulate alpha(v)beta(3) and alpha(v)beta(5) integrins. In addition, zoledronic acid (Zometa; Novartis Pharmaceuticals Corp.; East Hanover, NJ and Basel, Switzerland) exerts synergistic antitumor activity when combined with other anticancer agents. Zoledronic acid also inhibits tumor cell adhesion to the extracellular matrix and invasion through Matrigel trade mark and has antiangiogenic activity. A growing body of evidence from animal models demonstrates that zoledronic acid and other bisphosphonates can reduce skeletal tumor burden and prevent metastasis to bone. Further studies are needed to fully elucidate these biochemical mechanisms and to determine if the antitumor potential of bisphosphonates translates to the clinical setting.     

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.     

Management of bone metastases in breast cancer

Opinion statement Patients with advanced breast cancer who develop bone metastases suffer an ongoing risk of skeletal complications that can have a significant impact on their quality of life (QoL). These complications include bone pain, pathologic fractures, spinal cord compression, and hypercalcemia of malignancy (HCM), a potentially life-threatening condition. Treatment options include radiotherapy to palliate bone pain and/ or prevent impending fracture, orthopedic surgery to prevent or repair fractures, analgesics, and bisphosphonates, which can significantly reduce the risk of skeletal complications and delay their onset. Of the known bisphosphonates, zoledronic acid is the most potent. Since its regulatory approval in the United States and Europe in 2001, zoledronic acid (4 mg by 15-minute infusion) has become widely used and has replaced pamidronate (90 mg by 2-hour infusion) as the standard of care for treating bone metastases from breast cancer and bone lesions from multiple myeloma. Zoledronic acid has also demonstrated significant long-term benefits in randomized trials in prostate cancer and other solid tumors, whereas other bisphosphonates have failed. In long-term, phase III clinical testing, zoledronic acid provided significant treatment benefits beyond those of pamidronate in patients with breast cancer and demonstrated a safety profile comparable with pamidronate. Therefore, zoledronic acid is now recommended from the first diagnosis of bone metastasis. Other intravenous bisphosphonates include clodronate and ibandronate. Both are approved in Europe, but their efficacy relative to pamidronate and zoledronic acid is not known.     

Bisphosphonate treatment recommendations for oncologists

Renal safety is an important consideration for oncologists who are treating patients with bisphosphonates. In recent years, there has been increasing awareness about the development of bisphosphonate-induced nephrotoxicity. This has emerged mainly from increased clinical experience with zoledronic acid (Zometa); Novartis Pharmaceuticals Corporation, East Hanover, NJ, http://www.pharma.us.novartis.com). For this reason, the U.S. and European product labels for i.v. zoledronic acid were recently updated to include additional renal safety cautions, including dose adjustment in patients with mild-to-moderate renal impairment. However, renal toxicity is not a class effect. The product label for ibandronate (Bondronat), F. Hoffmann-La Roche Ltd., Basel, Switzerland, http://www.roche.com) has remained unchanged since the launch of the drug in the European Union in 2003. Ibandronate does not require mandatory monitoring of kidney function prior to each infusion. In addition, ibandronate can be used in patients with varying degrees of renal impairment. It also can be used without restrictions for nephrotoxic medications, and dose adjustment is only required in patients with severe renal impairment. Clinical implications of the renal safety of ibandronate include reducing the physician and nursing time needed for managing the adverse renal events associated with bisphosphonate therapy and dosing based on renal function. There also are no added renal safety risks and fewer inconvenient hospital visits with ibandronate therapy. In addition to i.v. ibandronate, an oral formulation of the drug is available. Oral ibandronate therapy is especially desirable because the medication is convenient (with a small, once-daily tablet that can be taken at home), reducing the health care costs associated with infusions. Clinical studies also indicate that 50 mg oral ibandronate has an efficacy similar to that of i.v. bisphosphonates and is associated with a low incidence of adverse gastrointestinal events.     

Bisphosphonates for treatment and prevention of bone metastases.

Bone metastases are a major cause of morbidity for men with prostate cancer. Complications of bone metastases include pain, fractures, and spinal cord compression. Although they appear osteoblastic by radiographic imaging, most bone metastases are characterized by excess osteoclast number and activity. In addition, pathologic osteoclast activation is associated with increased risk of skeletal complications. Zoledronic acid, a potent inhibitor of osteoclast activity, differentiation, and survival, decreases the risk of skeletal complications in men with androgen-independent prostate cancer and bone metastases. Other bisphosphonates, including pamidronate and clodronate, seem to be ineffective in this setting. The reduction in risk of skeletal complications with zoledronic acid must be weighed against potential adverse effects. Additional studies are needed to determine the optimal timing, schedule, and duration of treatment in men with bone metastases as well as the potential role of bisphosphonates in other settings including the prevention of bone metastases.     

Approval summary for zoledronic acid for treatment of multiple myeloma and cancer bone metastases.

PURPOSE: This article summarizes data submitted to the United States Food and Drug Administration for marketing approval of zoledronic acid (Zol; Novartis Pharmaceuticals, East Hanover, NJ), a bisphosphonate drug for treating patients with bone metastases. Experimental Design: We review the chemistry, toxicology, pharmacology, and clinical study results submitted to support the supplemental New Drug Application for Zol for treatment of patients with bone metastases. Four- and 8-mg Zol doses were selected for Phase III trials based on bone resorption markers and clinical efficacy parameters. Patients with bone metastases were randomized in three Phase III studies (prostate cancer, solid tumors, and multiple myeloma or breast cancer) to receive 4 or 8 mg of Zol or to a control arm. The control was a placebo in the prostate cancer study and the other solid tumor study and was 90 mg of pamidronate (Pam) in the study of breast cancer and multiple myeloma. Studies were amended twice because of renal toxicity, initially to increase Zol infusion time from 5 to 15 min and later to decrease the dose in the Zol 8-mg arm to 4 mg. The efficacy end point was skeletal-related events (SREs), a composite end point consisting of pathologic fracture, radiation therapy to bone, changes in antineoplastic therapy for bone pain (prostate cancer only), surgery to bone, or spinal cord compression. This end point was analyzed either as the proportion of patients with SRE or time to first SRE. The breast cancer and myeloma study used a noninferiority statistical analysis methods to determine efficacy. RESULTS: In prostate cancer, both the proportions analysis and time-to-SRE analysis showed significantly less bone morbidity on Zol (4 mg) than placebo, but no significant difference between Zol (8 mg) and placebo in either analysis. In the solid tumor study, the time to SRE analysis but not the proportions analysis showed significantly less skeletal morbidity on Zol (4 mg) than placebo, and Zol (8 mg) was significantly better than placebo in both analyses. The breast cancer and myeloma study demonstrated noninferiority of Zol compared with Pam, with Zol retaining at least 49.3% of the Pam treatment effect previously demonstrated in placebo-controlled trials. Zol was approved on February 22, 2002, by the United States Food and Drug Administration for the "treatment of patients with multiple myeloma and documented bone metastases from solid tumors, in conjunction with standard antineoplastic therapy. Prostate cancer should have progressed after treatment with at least one hormonal therapy." The recommended dose and schedule is 4 mg of Zol infused over 15 min every 3-4 weeks. Increased Zol doses and shorter infusions are not recommended because of potential renal toxicity.     

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.     

Myeloma bone disease: pathophysiology and management.

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

Safety and efficacy of bisphosphonates beyond 24 months in cancer patients.

PURPOSE: Bisphosphonate therapy has decreased the risk of skeletal complications associated with osteolytic bone lesions in patients with breast cancer and multiple myeloma. The large prospective studies have used 21 to 24 months of treatment. We studied the safety and efficacy of bisphosphonates in a subset of patients who received therapy for more than 24 months. PATIENTS AND METHODS: Patients who received bisphosphonates (pamidronate or zoledronic acid) were identified. Data on skeletal events and laboratory parameters were gathered by chart review. RESULTS: We studied 22 patients who received intravenous pamidronate or zoledronic acid for a duration of 3.6 years (range, 2.2 to 6.0 years). Prolonged therapy was well tolerated. No significant calcium, phosphorus, electrolyte, or WBC count abnormalities were encountered. There was a clinically insignificant decrease in hemoglobin and platelet count and an increase in creatinine in these patients. The fracture rate beyond 2 years was no greater than during the first 2 years of treatment. There were no stress fractures of long bones with prolonged therapy. CONCLUSION: Prolonged treatment with the potent bisphosphonates pamidronate and zoledronic acid seems to be well tolerated and should be studied in prospective, randomized studies to document prolonged skeletal efficacy.     

Prevention and Treatment of Myeloma Bone Disease

Osteolytic bone disease is the most common complication of multiple myeloma, resulting in skeletal-related events (SREs) that cause significant morbidity. Bone destruction in myeloma is due to an increased activity of osteoclasts coupled with suppressed bone formation by osteoblasts. Currently, bisphosphonates are the mainstay of the treatment of myeloma bone disease. Zoledronic acid and pamidronate have shown similar efficacy in reducing SREs in a randomized study in the conventional chemotherapy era. However, in a recent study (the Myeloma-IX trial of the UK Medical Research Council, MRC), zoledronic acid was found to be superior to clodronate in reducing SREs, but also it produced a survival advantage of approximately 10?months in patients with bone disease at baseline. During recent years, novel agents targeting bone have been used in myeloma. This review focuses on the established therapy of myeloma bone disease and also on recent advances in treatment that take advantage of the better understanding of the pathophysiology of bone disease.     

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.     

Bone disease in myeloma

Opinion statement The major clinical manifestation of multiple myeloma results from osteolytic bone destruction. The only currently Food and Drug Administration-approved drug for the treatment of the bony complications of multiple myeloma is monthly intravenous pamidronate at a dose of 90 mg infused over 4 hours. Recent studies have shown the safety of 2-hour infusions. A randomized trial comparing pamidronate to placebo continued to show benefits throughout the 21-month trial. Although the duration of therapy has not been firmly determined, it is likely that discontinuation of this drug will be met by enhanced bone loss and an increased risk of bony complications for these patients. Thus, it is recommended that the drug be continued indefinitely. Support for this recommendation also comes from the reduced bone density observed in women with postmenopausal osteoporosis following the withdrawal of bisphosphonate treatment. Recent attempts to give higher doses, more frequent infusions (every 2 weeks or less), or more rapid infusions (1 hour or less) of pamidronate have occasionally been associated with albuminuria and azotemia. These modifications should therefore be avoided. Importantly, the drug can be safely administered at 90 mg monthly to patients with poor renal function. The use of pamidronate for myeloma patients without lytic bone involvement or with Durie-Salmon stages I or II disease has not been evaluated. However, it is recognized that most patients with earlier stages of disease or without lytic bone involvement also develop bony complications. There is no reason to believe that these patients would not benefit from monthly intravenous infusions of pamidronate. The potential antimyeloma effect of this agent is another reason to administer this drug in these types of patients. Thus, it is our practice to administer monthly pamidronate to myeloma patients regardless of stage or bone involvement. However, trials evaluating oral bisphosphonates have produced inconsistent clinical results, probably as a result of the erratic and scanty poor absorption as well as poor oral tolerability of these drugs. Although these oral agents may be useful in some patients, it is impossible to identify which myeloma patients will benefit from orally administered bisphosphonates. The more potent nitrogen-containing bisphosphonate zoledronic acid more effectively reverses hypercalcemia of malignancy than pamidronate, and it appears promising in reducing bone loss in cancer patients. However, its efficacy in preventing skeletal complications is still being evaluated. Many other types of new agents are in early clinical trials, but their efficacy remains unproven at the present time.     

Long-term efficacy and safety of zoledronic acid compared with pamidronate disodium in the treatment of skeletal complications in patients with advanced multiple myeloma or breast carcinoma: a randomized, double-blind, multicenter, comparative trial

BACKGROUND: The goal of the current study was to compare the long-term (25-month) safety and efficacy of zoledronic acid with pamidronate in patients with bone lesions secondary to advanced breast carcinoma or multiple myeloma. METHODS: Patients (n = 1648) were randomized to receive 4 mg or 8 mg (reduced to 4 mg) zoledronic acid as a 15-minute infusion or to receive 90 mg pamidronate as a 2-hour infusion every 3-4 weeks for 24 months. The primary endpoint was the proportion of patients with at least 1 skeletal-related event (SRE), defined as pathologic fracture, spinal cord compression, radiation therapy, or surgery to bone. Secondary analyses included time to first SRE, skeletal morbidity rate, and multiple-event analysis. Hypercalcemia of malignancy (HCM) was included as an SRE in some secondary analyses. RESULTS: After 25 months of follow-up, zoledronic acid reduced the overall proportion of patients with an SRE and reduced the skeletal morbidity rate similar to pamidronate. Compared with pamidronate, zoledronic acid (4 mg) reduced the overall risk of developing skeletal complications (including HCM) by an additional 16% (P = 0.030). In patients with breast carcinoma, zoledronic acid (4 mg) was significantly more effective than pamidronate, reducing the risk of SREs by an additional 20% (P = 0.025) compared with pamidronate and by an additional 30% in patients receiving hormonal therapy (P = 0.009). Zoledronic acid (4 mg) and pamidronate were tolerated equally well. The most common adverse events included bone pain, nausea, and fatigue. CONCLUSIONS: Long-term follow-up data confirm that zoledronic acid was more effective than pamidronate in reducing the risk of skeletal complications in patients with bone metastases from breast carcinoma and was of similar efficacy in patients with multiple myeloma.     

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.     

Efficacy and safety of intravenous bisphosphonates for patients with breast cancer metastatic to bone: a review of randomized, double-blind, phase III trials

Intravenous bisphosphonates are the preferred treatment to prevent skeletal complications for patients with breast cancer and bone metastases. Pamidronate, a single-nitrogen bisphosphonate, was the early standard of care for such patients based on 2 large, placebo-controlled trials involving 754 patients. Zoledronic acid, a new-generation bisphosphonate containing 2 nitrogens, was evaluated in 1130 patients with breast cancer in a large, randomized, comparative, phase III trial with pamidronate. At 25 months, zoledronic acid (4 mg) significantly reduced the overall risk of developing a skeletal-related event (SRE) by an additional 20% versus 90 mg pamidronate by multiple-event analysis. Furthermore, zoledronic acid was at least as effective as pamidronate in reducing the proportion of patients with > or = 1 SRE and in delaying the onset of SREs. Moreover, a retrospective subset analysis of 352 patients with > or = 1 osteolytic lesion proved zoledronic acid more effective than pamidronate in reducing the risk and delaying the onset of SREs. Intravenous ibandronate (6 mg via 1-2-hour infusion) was evaluated in a placebo-controlled, phase III trial of 466 patients and was significantly more effective than placebo in reducing the number of 12-week treatment periods in which an SRE occurred. The safety profiles among all intravenous bisphosphonates were similar; patients treated with intravenous bisphosphonates reported notably less bone pain but a higher incidence of mild to moderate transient infusion-related adverse events (eg, nausea, vomiting, myalgia, and anorexia) compared with placebo. In summary, intravenous bisphosphonates are effective for the treatment of bone metastases in patients with breast cancer and have similar safety profiles, but the shorter infusion time and greater efficacy of zoledronic acid in reducing overall skeletal morbidity provide advantages over other available agents.     

The role of bisphosphonates in the management of advanced cancer with a focus on non-small-cell lung cancer. Part 1: Mechanisms of action, role of biomarkers and preclinical applications

With recent advances in cancer management, patients with metastatic bone disease are likely to have a prolonged clinical course, with skeletal-related events such as pain, hypercalcemia, pathologic fractures, spinal cord and nerve compression. Bisphosphonate use has resulted in the reduction of skeletal-related complications for a number of tumors including breast, prostate and myeloma, and improvements in the quality of life for patients. There is now evidence that newer, highly potent, nitrogen-containing bisphosphonates reduce skeletal complications in patients with bone metastases from other solid tumors (including lung cancer). The early identification of patients at high risk for developing bone metastases may help curtail a complex and costly clinical problem--skeletal-related events. In this article, we review the different mechanisms of bisphosphonates and the potential role of newer-generation bisphosphonates, such as zoledronic acid, in the management of advanced, metastatic bone disease. We include a review of mechanistic studies and preclinical data. Additionally, the utility of evolving concepts such as bone markers and imaging of bone metastases are discussed.     

Bisphosphonate as an adjuvant therapy for the pain of bone metastases, 3 cases

Pain from bone metastases limits mobility and may cause pathological fractures that can seriously impair the patient's quality of life. Conservative treatments such as orthopedic fixation, radiotherapy, and opioids sometimes fail to give satisfactory pain relief. Bisphosphonates have been reported to reduce the severity of pain from bone metastasis due to breast cancer, prostate cancer, and multiple myeloma. Recent clinical reports demonstrated the effectiveness of bisphosphonates in reducing pain from bone metastases in various malignancies. This study presents 3 cases of refractory pain from bone metastases due to thyroid, colorectal and hepatocellular carcinoma. Primary treatment included orthopedic fixation, radiotherapy, and/or parenteral opioids that failed to reduce bone pain. Bisphosphonate therapy was considered at the start of pain control treatment using opioids. All 3 cases showed gradual reduction in pain after i.v. pamidronate administration and allowed physicians to control further pain with opioids. In 1 case, the patient was successfully withdrawn from opioids. The role of bisphosphonates in painful bone metastases remains unclear. However, recent encouraging reports have indicated that bisphosphonate may become one of the adjuvant treatments available to control refractory bone pain from various malignancies.