Dose-response study of ibandronate in the treatment of cancer-associated hypercalcaemia

Repurposing amino-bisphosphonates by liposome formulation for a new role in cancer treatment

Amino-bisphosphonates (N-BPs) have been commercially available for over four decades and are used for the treatment of osteoporosis, Paget's disease, hypercalcemia of malignancy, and bone metastases derived from various cancer types. Zoledronate and alendronate, two of the most potent N-BPs, have demonstrated direct tumoricidal activity on tumor cells and immune modulatory effects on myeloid cells and T cells in vitro and in animal models of cancer. However, the rapid renal clearance and sequestration in mineral bone of these drugs in free form severely limit their systemic exposure and applications in cancer patients. Reformulation of N-BPs by encapsulation in liposomal nanoparticles addresses these pharmacokinetic barriers, and liposomal zoledronate and alendronate formulations have been found to increase the anticancer efficacy of cytotoxic chemotherapies and adoptive T cell immunotherapies in murine cancer models. Herein, we review the differences in pharmacology between N-BPs versus non-N-BPs (e.g., clodronate), free versus liposomal N-BP formulations, and targeted versus non-targeted liposomal N-BPs, and the clinical and preclinical evidence supporting a role for liposomal N-BPs in the treatment of cancer. We propose that pegylated liposomal alendronate (PLA) has the most potential for clinical translation based on favorable therapeutic index, ability to passively target and accumulate in tumors, proven biocompatibility of the liposome carrier, and preclinical anticancer efficacy.

Bisphosphonates: AHFS 92:24

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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.

Ibandronate: its pharmacology and clinical efficacy in the management of tumor-induced hypercalcemia and metastatic bone disease

It is well accepted that tumor cells in the bone, especially from breast cancer, prostate cancer and multiple myeloma, can stimulate osteoclast formation and activity. Bisphosphonates are potent inhibitors of osteoclast-mediated normal and pathologic bone resorption. Besides their apoptotic and antiproliferative activity on osteoclasts, bisphosphonates can also exert similar effects on macrophages and tumor cells. Currently, it is unknown if this effect can be translated into clinical practice with regard to an effective adjuvant therapeutic regimen for high-risk patients with systemic recurrences following primary treatment of a given cancer. There are several new aspects that might extend the clinical use of ibandronate, a bisphosphate, in oncology: prevention of hypogonadal osteoporosis in men, palliative management of painful osseous metastases and adjuvant therapy of high-risk prostate cancer patients. Safety and tolerability are excellent for the oral and intravenous formulations, and ibandronate can even be safely applied in pre-existing renal insufficiency. The purpose of this review is to critically reflect the pharmacology and clinical efficacy of ibandronate in the management of tumor-induced hypercalcemia, osteoporosis and metastatic bone disease.

The significance of early diagnosis of cancer-related hypercalcaemia

Cancer-related hypercalcaemia is one of the most common life-threatening metabolic disorders. It occurs in 20% to 30% of patients with cancer during the course of the disease, which depends on tumour type, too. There are two types of cancer-related hypercalcemia: humoral hypercalcemia and local osteolytic hypercalcaemia. Malignant hypercalcaemia is mediated by several circulating factors secreted by malignant cells. The biological actions of these factors are primarily stimulation of osteoclasts to resorb bone and, secondly, stimulation of calcium reabsorption at the renal tubules resulting in an elevation of serum calcium level. Diagnosis of hypercalcaemia is relatively difficult due to the non-specific clinical signs as well as the underlying malignancy and the side-effects of palliative medical treatment. Consequently, cancer-related hypercalcaemia is underdiagnosed quite often. Unrecognised malignant hypercalcaemia can lead to death. Nowadays 90% of hypercalcaemia can be treated with administration of intravenous saline containing fluids and bisphosphonates. Literature data suggest that hypercalcaemia is treated in less than 40% of hospitalized patients properly due to diagnostic errors and mismanagement. Orv. Hetil., 2013, 154, 1367–1373.

Bisphosphonates in Breast Cancer Patients with Bone Metastases

Morbidity and mortality in breast cancer patients are mainly caused by organ failure as a result of distant metastasis. The main target of metastatic disease is the skeleton (next to lungs and liver). Osseous metastases are diagnosed in 75-80% of all women who die due to breast cancer; and the skeleton is the primary metastatic target organ in more than half of these cases. In Germany, the incidence of breast cancer patients with newly diagnosed bone metastases is approximately 11-12,000 cases. Prevalence might amount to 40,000 cases of women with breast cancer and osseous metastases at a median survival time of 3-4 years. The treatment goal at this stage of the disease comprises improvement of quality of life, and reduction of bone pain and typical complications like fractures and hypercalcemia. By consistent use of bisphosphonates these goals can be accomplished. Bisphosphonates improve bone pain significantly and reduce the number of skeletal-related events in women with bone metastases. Bisphosphonates can be administered intravenously or orally, and are well tolerated. Nevertheless, there are side effects and complications including acute phase reaction, nephrotoxicity, osteonecrosis of the jaw, and gastrointestinal disturbances.

Endocrine and metabolic emergencies: hypercalcaemia

Hypercalcaemia is commonly seen in the context of parathyroid dysfunction and malignancy and, when severe, can precipitate Life-threatening sequelae. The differential of hypercalcaemia is broad and can be categorized based on parathyroid hormone (PTH) Levels. The acute management of severe hypercalcaemia is discussed along with a brief review of therapeutic advances in the field.

Poor Survival Outcome With Moderate and Severe Hypercalcemia in Gynecologic Malignancy Patients

Objective:

Determine the incidence of hypercalcemia in gynecologic malignancy patients and their survival outcome.

Design:

Single-institution retrospective clinical study.

Patients and Methods:

We used Fisher exact test, Kaplan-Meier survival curves, and Cox proportional hazards model to analyze demographic and clinical data from gynecologic malignancy patients with hypercalcemia who had been treated at The University of Texas M. D. Anderson Cancer Center from September 1997 to August 2006.

Results:

Of the 5260 gynecologic malignancy patients, 268 had hypercalcemia (5%). Of the 268, 12 were excluded because of hyperparathyroidism or coexisting malignancies; thus, 256 patients were included in the study. Most patients (82%) had mild hypercalcemia. Severity of hypercalcemia was associated with disease stage (P = 0.0019), use of hypercalcemia treatment (P < 0.0001), and survival duration (P < 0.0001). The median survival duration of patients who had not been treated for hypercalcemia was 432 days compared with 106 days in patients who had been treated. The shorter survival duration of treated patients seems to result from their disease status and hypercalcemia severity rather than whether they were treated for hypercalcemia.

Conclusions:

Moderate and severe hypercalcemia is associated with poorer survival duration in gynecologic malignancy patients. Early detection and treatment of hypercalcemia in these patients may prolong survival. To our knowledge, this is the first study of hypercalcemia in patients with general gynecologic malignancy.

Effects of ibandronate on bone quality: preclinical studies

Osteoporosis is a skeletal disorder characterized by low bone mass and deterioration of bone microarchitecture resulting in bone fragility, which increases the risk of fracture. The clinical efficacy of bisphosphonates is evaluated through improvements in bone mineral density (BMD) and reductions in the risk for fracture. However, as bisphosphonates are administered long term, there is increasing interest in their effects on bone quality, which includes bone mass, strength and architecture. Ibandronate is a potent, nitrogen-containing bisphosphonate with significant antifracture efficacy when administered daily and in regimens with extended between-dose intervals. Clinical studies with ibandronate are supported by an extensive preclinical program that investigated the efficacy and bone safety of ibandronate in various animal models of osteoporosis. In preclinical studies, treatment with ibandronate maintained, or improved the quality, strength and architecture of bone. Intermittent and daily ibandronate regimens provided similar benefits. During ibandronate treatment, the bone retains its capacity for repair and bone mineralization is not adversely affected. Notably, positive relationships among BMD, bone strength and bone architecture have been demonstrated. This review describes the preclinical evidence for the preservation of bone quality with ibandronate, irrespective of the dosing regimen and even when administered at doses higher than those used therapeutically.

Ibandronate for the treatment of hypercalcemia or nephrocalcinosis in patients with multiple myeloma and acute renal failure: Case reports

Multiple myeloma disrupts calcium homeostasis by a variety of mechanisms, including bone destruction and resorption. This causes hypercalcemia. When left untreated, hypercalcemia leads to nephrocalcinosis, impairment of kidney function, and eventually renal failure. Some degree of renal dysfunction is common in myeloma patients. Here, we report case studies showing the efficacy and renal safety of the single-nitrogen bisphosphonate, ibandronate, for the treatment of hypercalcemia and/or nephrocalcinosis in multiple myeloma patients hospitalized with acute renal failure. Patients (n = 7) received either one or two intravenous infusions of ibandronate (2-6 mg). Ibandronate was well tolerated in all patients and returned elevated blood calcium levels to normal. Renal function improved for all patients and normalized in 3/7 patients. We conclude that ibandronate is involved in rapidly improving or restoring acute renal function and calcium levels to within the normal range in this patient population. To clarify the exact value of ibandronate, further investigation is warranted in randomized prospective trials.

Ibandronate, an experimental intravenous bisphosphonate for osteoporosis, bone metastases, and hypercalcemia of malignancy

Ibandronate is an experimental intravenous bisphosphonate under study for the prevention or treatment of osteoporosis and skeletal complications of bone metastases, as well as hypercalcemia of malignancy. To review the data on this drug, PubMed/MEDLINE was searched for pertinent studies in English; data from January 1986-October 2005 were reviewed. In preclinical studies, ibandronate was an extremely potent bisphosphonate compared with its predecessors and was active in all animal models of human postmenopausal and corticosteroid-associated osteoporosis. Similar to other bisphosphonates, ibandronate exhibits antitumor activity and prevents or reduces bone metastases. Forty to fifty percent of the dose is bound to bone; renal clearance of unchanged drug accounts for 70% of total body clearance. Early clinical trials demonstrated efficacy and tolerability of intravenous ibandronate in the prevention or treatment of postmenopausal and corticosteroid-associated osteoporosis when administered once every 3 months. Intravenous ibandronate also reduces skeletal complications of bone metastases, including pain, although the cumulative dose used is much higher than that used in osteoporosis, as the drug is administered every 3-4 weeks. Single doses of intravenous ibandronate are probably also effective in the treatment of hypercalcemia of malignancy. The major tolerability issue with intravenous bisphosphonates is renal safety, thus the drugs generally require infusion (e.g., 0.25 hr for zoledronic acid, 2-24 hrs for pamidronate). However, intravenous ibandronate can be administered by bolus injection over a few minutes without an elevated risk of nephrotoxicity. The experimental intravenous dosage is 2 mg every 3 months for treatment or prevention of osteoporosis, and 2-6 mg every 3-4 weeks or in a single dose for treatment of bone metastases or hypercalcemia of malignancy, respectively. Ibandronate can be used in the presence of severe renal impairment with proper dosage adjustment. The drug will be an interesting addition to the available drugs for osteoporosis, bone metastases, and hypercalcemia of malignancy. Studies of intravenous ibandronate as an adjunctive treatment for cancers that tend to metastasize to bone are under way. Whether intravenous ibandronate will be a therapeutic advance is best answered by randomized, controlled trials. These are ongoing and should provide data with which to make better-informed choices concerning intravenous bisphosphonates.

Ibandronate Intravenous

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High dosage treatment of nitrogen-containing bisphosphonate ibandronate is required for osseointegration of cementless metal implants

BACKGROUND

There is evidence that application of a bisphosphonate can improve fixation of cementless metal implants by enhancing the extent of osseointegration, but the required dose regimen is still under discussion. The current preclinical study was designed to determine the optimal treatment dose of the nitrogen-containing bisphosphonate ibandronate to improve osseointegration of cementless metal implants.

METHODS

The study was conducted in 52 female Sprague-Dawley rats in which uncoated and hydroxyapatite-coated titanium implants were surgically inserted into the medullary canal of each femur. The animals were randomly assigned to receive subcutaneous treatment with ibandronate 1 microg/kg body weight (osteoporosis dose) or 25 microg/kg (tumor dose) per day or saline solution for control.

RESULTS

Histomorphometric evaluation revealed a significant enhanced extent of osseointegrated implant surface in the high-dose treatment group for both implants compared to the low-dose group and the control group. No significant differences were observed between the two implants in any group.

CONCLUSIONS

The results of the present study indicate that improved osseointegration of hydroxyapatite-coated and uncoated titanium implants is dose-dependent and requires high-dose application of bisphosphonate ibandronate equivalent to that needed to treat patients with tumor disease. Lower doses equivalent to those for treatment of osteoporosis showed no beneficial effect.

Analytical methods for the quantification of ibandronate in body fluids and bone

The accurate determination of bisphosphonate levels in bone and biological fluids is important in both clinical and pharmacological/toxicological studies. Ibandronate is a potent nitrogen-containing bisphosphonate containing a tertiary amine group, which does not easily form chromophore derivatives that can be detected by UV light or fluorescence emissions. The current report describes the methodology and validation of a GC-MS assay for ibandronate in serum/plasma and urine, a similar, modified GC-MS method for measurement of bone ibandronate levels, and an ELISA for ibandronate determination in serum/plasma. The range of quantification for the GC-MS was 1-100 ng/ml and 2-7500 ng/ml in plasma or serum and urine, respectively, and 50-1600 pg/ml (potentially 10-320 pg/ml depending on sample size) for the ELISA in plasma or serum. These assays were comparable. The practical application of the assays in preclinical and clinical studies is briefly reviewed.

The inhibition of RANKL causes greater suppression of bone resorption and hypercalcemia compared with bisphosphonates in two models of humoral hypercalcemia of malignancy

Humoral hypercalcemia of malignancy (HHM) is mediated primarily by skeletal and renal responses to tumor-derived PTHrP. PTHrP mobilizes calcium from bone by inducing the expression of receptor activator for nuclear factor-kappaB ligand (RANKL), a protein that is essential for osteoclast formation, activation, and survival. RANKL does not influence renal calcium reabsorption, so RANKL inhibition is a rational approach to selectively block, and thereby reveal, the relative contribution of bone calcium to HHM. We used the RANKL inhibitor osteoprotegerin (OPG) to evaluate the role of osteoclast-mediated hypercalcemia in two murine models of HHM. Hypercalcemia was induced either by sc inoculation of syngeneic colon (C-26) adenocarcinoma cells or by sc injection of high-dose recombinant PTHrP (0.5 mg/kg, s.c., twice per day). In both models, OPG (0.2-5 mg/kg) caused rapid reversal of established hypercalcemia, and the speed and duration of hypercalcemia suppression were significantly greater with OPG (5 mg/kg) than with high-dose bisphosphonates (pamidronate or zoledronic acid, 5 mg/kg). OPG also caused greater reductions in osteoclast surface and biochemical markers of bone resorption compared with either bisphosphonate. In both models, hypercalcemia gradually returned despite clear evidence of ongoing suppression of bone resorption by OPG. These data demonstrate that osteoclasts and RANKL are important mediators of HHM, particularly in the early stages of the condition. Aggressive antiresorptive therapy with a RANKL inhibitor therefore might be a rational approach to controlling HHM.

Current management strategies for hypercalcemia

The two most common causes of hypercalcemia are primary hyperparathyroidism and neoplastic disease. Parathyroidectomy is the only curative intervention for the former condition. In the rare cases of patients with primary hyperparathyroidism who present with clinical symptoms due to their hypercalcemia, pharmacological treatment may be required. Fluid repletion and intravenous (IV) administration of bisphosphonates are recommended in the literature. Calcium receptor agonists (calcimimetic agents) are at the present time only available for use within clinical trials. Cancer patients usually present with symptoms of hypercalcemia. Rapid institution of antihypercalcemic treatment is essential in preventing life-threatening deterioration. Fluid repletion and administration of bisphosphonates are the treatment mainstays in hypercalcemia of malignancy. Five bisphosphonates are currently licensed in Europe for treatment of tumor-associated hypercalcemia: etidronate, clodronate, pamidronate, ibandronate, and zoledronate. In the US, pamidronate and zoledronate are licensed for use in this indication. Bisphosphonates containing nitrogen atoms (e.g. pamidronate, ibandronate, and zoledronate) are more potent than those without (e.g. etidronate, clodronate, and tiludronate). In patients with malignant hypercalcemia, the efficacy of the individual bisphosphonate depends on dose administered and initial serum calcium concentration. At present, pamidronate has been studied in the greatest number of investigations and in the largest number of patients. In the literature, the efficacy of pamidronate in restoring normocalcemia ranges between 40% and 100%, depending on the dose used and baseline serum calcium concentration. More recently, one study reported that pamidronate was inferior to zoledronate. In this study, the duration of response was also longer in the two zoledronate groups (30 and 40 days) than in the pamidronate group (17 days). The most serious adverse events of bisphosphonates concern renal function. Increases in serum creatinine levels have been more frequently reported following treatment of tumor-associated hypercalcemia with etidronate (8%) and clodronate (5%) than with the nitrogen-containing bisphosphonates pamidronate (2%) and ibandronate (1%). The frequency of increases in serum creatinine levels following treatment with zoledronate is difficult to estimate. Administration of the nitrogen-containing bisphosphonates has been associated with transient (usually mild) fever, lymphocytopenia, malaise, and myalgias. These events occur within 36 hours of the first dose and are self-limiting. Hypocalcemia occurs in up to 50% of patients treated with bisphosphonates for hypercalcemia of malignancy, although symptomatic hypocalcemia is rare. The toxicity and low efficacy of plicamycin (mithramycin) mean that use of this agent should be restricted to patients with hypercalcemia of malignancy who fail to respond to IV bisphosphonates. Calcitonin is characterized by good tolerability but poor efficacy in normalizing the serum calcium level. However, a major advantage of calcitonin is the acute onset of the hypocalcemic effect, which contrasts with the delayed but more pronounced effect of bisphosphonates. Combination calcitonin and bisphosphonate treatment may therefore be of value when rapid reduction of serum calcium is warranted. Gallium nitrate may be a valuable treatment for hypercalcemia of malignancy. It is characterized by high efficacy and few adverse events apart from renal toxicity (10% of cases). However, data are very limited and further trials are necessary.

Bisfosfonatos intravenosos

Bisphosphonates possess a fundamental role in the treatment of bone metabolic diseases. Yet their main limitations are poor oral absorption and gastrointestinal side effects, mainly esophageal irritation. Indeed, oral administration is unpleasant for many patients, and it is difficult in bed-confined subjects. Therefore, intravenous administration of these agents can be very useful in several clinical scenarios, especially to improve the compliance. Recently, it has been showed that intravenous bisphosphonates are very useful to control hypercalcemia of malignancy, and to prevent bone complications related to metastases. Their use has also been analyzed in the prevention of bone disease after organ transplantation. Thus, their application to control Paget's disease of bone is well-known, and probably they could have an important role as antiresorptive agents in postmenopausal and steroidal osteoporosis. We present here a state of the art of the use of intravenous bisphosphonates for the aforementioned disorders.

Olpadronate: a new amino-bisphosphonate for the treatment of medical osteopathies

Olpadronate is a nitrogenated bisphosphonate. Although it shares the therapeutic and pharmacological properties of pamidronate and alendronate, it has a greater dosage amplitude, more predictable effects and a greater digestive tolerability than other bisphosphates. Therefore, it may be more appropriate in the treatment of medical osteopathies, by both oral and parenteral routes of administration. According to various experimental and human models, the pharmacological potency of olpadronate is 5- to 10-times higher than that of pamidronate and close to that of alendronate. The two methyl groups bound to the nitrogen atom give the compound a high water solubility, which is about 8-times higher than that of the two other bisphosphonates. The lack of a terminal amino group in the side-chain of the molecule and the absence of crystallised forms of the compound in the digestive tract (due to its high water solubility) may avoid the potential for inducing oesophageal and gastrointestinal side-effects. These features may explain the high tolerability reported after the administration of doses of olpadronate (by the oral route) up to 5- to 10-times higher than the maximum tolerated dose of alendronate in Paget's bone disease and bone metastases, thus widening the possibilities for its clinical usage. In addition, initial pharmacokinetic studies suggest that olpadronate's oral bioavailability would fit into a confidence range of 2-4%, which contrasts with the erratic absorption shown by other highly potent bisphosphonates. The clinical efficacy demonstrated in preliminary studies in Paget's bone disease (including ultra-short treatments), and also in single-dose iv. therapy of hypercalcaemia of malignancies, renders olpadronate among the most promising bisphosphonate compounds, with potential use in the treatment of a variety of bone-involving diseases, such as osteoporosis, malignancies and rheumatoid arthritis.

New model for simulation of fracture repair in full-grown beagle dogs: model characterization and results from a long-term study with ibandronate

INTRODUCTION

Given that bisphosphonates reduce bone turnover, it is important to establish that their long-term administration does not impair bone quality. This paper describes a new model for simulation of fracture repair to evaluate several aspects of bone quality following long-term administration (34 or 36 weeks) of ibandronate in full-grown beagle dogs.

METHODS

The treatment schedule consisted of continuous daily subcutaneous administration of a pharmacologically active dose (1 microg/kg/day) and two cyclical intermittent regimens providing a similar total dose per animal at the end of the experiment. Seven or 8 weeks before study end, 10 holes were drilled in the left tibia and bone marrow ablation was performed in the ipsilateral femur. Serial measurements for blood biochemistry (osteocalcin and iso-alkaline phosphatase) and bone mineral density (BMD; whole body and L1-L7) by dual-energy X-ray absorptiometry (DEXA) were performed during the experiment. Bone quality was determined at the end of the experiment by assessing early and late stage defect healing and structural, cellular, and dynamic histomorphometry (femur, tibia, and lumbar vertebrae L3 and L4).

RESULTS

Healing of the drill hole defects, which simulate the first stage of fracture healing, was neither qualitatively nor quantitatively influenced by ibandronate. The same was true for the activation of cortical remodeling that occurs in the later stage of fracture healing, which started in Week 4 after surgery and declined after Week 8 in all groups. Additionally, no difference was found between the various regimens and the controls with respect to DEXA analyses, trabecular bone volume, cancellous bone tissue area, cancellous bone perimeter, osteoclast count, serum osteocalcin, or bone-specific alkaline phosphatase.

DISCUSSION

In conclusion, the presence of the first and second steps of fracture healing and the fact that the histological features closely resemble those of fracture repair validate the development and characterization of a new model for simulation of fracture repair. A long-term study with a therapeutically active dose of ibandronate shows that ibandronate does not impair BMD, bone structure, bone repair, coupling, and serum parameters for bone formation and turnover after long-term administration.

Ibandronate: a clinical pharmacological and pharmacokinetic update

Ibandronate is a potent nitrogen-containing bisphosphonate. It has a strong affinity for bone mineral and potently inhibits osteoclast-mediated bone resorption. Ibandronate is effective for the treatment of hypercalcemia of malignancy, metastatic bone disease, postmenopausal osteoporosis, corticosteroid-induced osteoporosis, and Paget's disease. Oral ibandronate is rapidly absorbed (t(max) < 1 hour), with a low bioavailability (0.63%) that is further reduced (by up to 90%) in the presence of food. Ibandronate has a wide therapeutic index and is not metabolized and, therefore, has a low potential for drug interactions. Given its metabolic stability, ibandronate is eliminated from the blood by partitioning into bone (40%-50%) and through renal clearance (CL(R) approximately 60 mL/min). The CL(R) of ibandronate is linearly related to creatinine clearance. The sequestration of ibandronate in bone (V(D) > 90 L) results in a multiphasic elimination (t((1/2)) range approximately 10-60 hours), characterized by the slow release of ibandronate from the bone compartment. The potency of ibandronate and its sequestration into bone allow ibandronate to be developed as oral and intravenous injection formulations that can be administered with convenient extended between-dose intervals.

Rapid administration of ibandronate does not affect renal functioning: evidence from clinical studies in metastatic bone disease and hypercalcaemia of malignancy

Ibandronate is a third-generation aminobisphosphonate that has an excellent safety record in hypercalcaemia of malignancy, and has recently been approved for the prevention of skeletal events from metastatic breast cancer. This paper reviews the safety data from clinical studies of intravenous ibandronate by infusion or injection, focusing on renal adverse events (AEs). In clinical trials of patients with hypercalcaemia of malignancy, 2-h infusions of ibandronate at doses of up to 6 mg had a low potential for renal events. In a phase III trial of patients with metastatic bone disease from breast cancer, 6 mg ibandronate infused over 1-2 h had a renal safety profile comparable to that of placebo. In pilot studies, repeated daily infusions of ibandronate (4 mg infused over 2 h for four consecutive days, or 6 mg infused over 1 h for three consecutive days) for severe metastatic bone pain were not associated with any renal AEs. The safety of single 15-min infusions of 6 mg ibandronate has been demonstrated in healthy volunteers and patients with metastatic bone disease from breast cancer or multiple myeloma. Furthermore, single and rapid bolus injections of 2 or 3 mg ibandronate did not increase the risk of renal dysfunction in patients with skeletal metastases. Implications for the renal safety of ibandronate in the management of patients with metastatic bone disease are discussed.

Systematic review of bisphosphonates for hypercalcaemia of malignancy

BACKGROUND

Bisphosphonates are the treatment of choice for hypercalcaemia of malignancy (HCM) but there is no consensus regarding which drug or dose should be given. We designed a systematic review to investigate the efficacy of bisphosphonates in the treatment of HCM.

METHODS

We identified randomized controlled trials (RCTs) by searching electronic databases, scanning of reference lists, and consultation with experts and pharmaceutical companies. Foreign papers were translated. Inclusion criteria were RCTs, confirmed malignant disease and measurement of serum calcium (ionized or corrected for albumin) postrehydration. The primary outcome was number of patients achieving normocalcaemia. Secondary outcomes were time to normocalcaemia, time to relapse and toxicity.

RESULTS

Twenty-seven papers and two abstracts, using intravenous bisphosphonates, fulfilled the inclusion criteria. Data from 26 studies were used in analyses. Due to the heterogeneity of studies, meta-analysis could not be performed. Pamidronate was more effective than placebo, mithramycin, etidronate (7.5 mg/kg) and low-dose clodronate (600 mg), but equal to higher dose clodronate (1500 mg). Clodronate and etidronate were superior to placebo; incadronate was superior to elcatonin; gallium nitrate was superior to etidronate. No difference was seen between alendronate and clodronate. Three dose finding studies showed no difference between 30-90 mg of pamidronate, but one well designed study showed increasing efficacy with increasing dose. Studies using increasing doses of ibandronate (0.6-4 mg), alendronate (2.5-15 mg), and incadronate (2.5-10mg), showed a dose response. Duration of administration of pamidronate did not affect efficacy (six studies).

CONCLUSION

Bisphosphonates normalize calcium in >70% patients with minimal side effects. Aminobisphosphonates are most effective at maintaining normocalcaemia and should be given in high dose irrespective of baseline serum calcium.

Improved quality of life after long-term treatment with the bisphosphonate ibandronate in patients with metastatic bone disease due to breast cancer

Bone metastases occur in most women with advanced breast cancer and can lead to considerable morbidity and a rapid deterioration in the patient's quality of life. It was the aim of the present study to assess changes in quality of life and bone pain due to intravenous (i.v.) ibandronate, a potent third-generation bisphosphonate. In a phase III randomised, double-blind, placebo-controlled trial in patients with bone metastases due to breast cancer, 466 women were randomised to receive placebo, 2 mg ibandronate or 6 mg ibandronate for up to 96 weeks. Treatment was administered i.v. at 3- or 4-weekly intervals. Clinical endpoints included the incidence of adverse events, quality of life (assessed using the European Organisation for the Research and Treatment of Cancer (EORTC) Quality of Life Scale - Core 30 questionnaire (QLQ-C30)), and bone pain (assessed on a 5-point scale from 0=none to 4=intolerable). Ibandronate was generally well tolerated. Compared with baseline measurements, the bone pain score was increased at the last assessment in both the placebo and 2 mg ibandronate groups, but was significantly reduced in the patients receiving 6 mg ibandronate (-0.28+/-1.11, P < 0.001). A significant improvement in quality of life was demonstrated for patients treated with ibandronate (P < 0.05) for all global health status. Overall, at the last assessment, the 6 mg ibandronate group showed significantly better functioning compared with placebo (P = 0.004), and had significantly better scores on the domains of physical, emotional, and social functioning, and in global health status (P < 0.05). Significant improvements in the symptoms of fatigue and pain were also observed in the 6 mg ibandronate group. I.v. ibandronate treatment leads to significant improvements in quality of life, and is an effective and well-tolerated palliative treatment in patients with bone metastases due to breast cancer.

Hypercalcemia of malignancy

Less than 25 years ago tumor-induced hypercalcemia was often a lethal complication of cancer. Nowadays, it can be treated easily and successfully in at least 90% of cases by volume repletion in addition to the use of bisphosphonates that are potent anti-osteoclastic compounds. The standard therapy consists of the administration of 90 mg pamidronate or, more recently, 4 mg zoledronic acid, a more efficient bisphosphonate. When available, another alternative bisphosphonate is ibandronate. Recurrent hypercalcemia is nevertheless difficult to control and antibodies against parathyroid hormone-related protein could be useful for that matter in selected patients who are not in the terminal stage of their disease. Prevention of tumor-induced hypercalcemia is one of the objectives of long-term therapy with bisphosphonates in patients with tumor bone disease. The use of bisphosphonates in placebo-controlled trials has shown that the incidence of hypercalcemic episodes is reduced by more than one half.

Ibandronate in osteoporosis: preclinical data and rationale for intermittent dosing

Ibandronate is a highly potent, nitrogen-containing bisphosphonate. Unlike most other bisphosphonates, it is under clinical development for both oral and intravenous (i.v.) administration. Ibandronate can be used in convenient intermittent regimens that may optimize therapeutic outcome with enhanced compliance by patients. The preclinical pharmacokinetics (PK) and pharmacology of ibandronate have been extensively explored in a large preclinical development program involving various recommended animal models of human osteoporosis. These experimental studies of ibandronate indicate that the preclinical pharmacology and PK profile of ibandronate are broadly similar to those of other nitrogen-containing bisphosphonates. The efficacy of intermittent administration of subcutaneous (s.c.) and i.v. ibandronate has been demonstrated in four animal models (rat, dog, minipig, and monkey). Thus in rats, dogs, and monkeys with estrogen depletion, and in minipigs with glucocorticoid-induced bone loss, ibandronate administered s.c. or i.v. with extended intervals between doses reduces bone turnover, increases bone mineral density, and maintains bone quality in a dose-dependent manner. Furthermore, studies in rats and dogs comparing continuous and intermittent treatment schedules indicate similar efficacy when the same cumulative dose is applied over the duration of the study. These studies with ibandronate illustrate the concept that the total cumulative dose of bisphosphonate administered determines the response, independent of whether the dose is given daily or less frequently in a given time period. The efficacy of intermittent regimens has also been verified in models of secondary osteoporosis due to secondary hyperparathyroidism or immobilization (both in rats), or due to glucocorticoids in minipigs. Important factors for determining efficacy and the magnitude of response are the doses given, the length of the interval between doses, and the underlying bone turnover rate. The mechanisms underlying the remarkable efficacy of intermittent bisphosphonate dosing are not fully understood and further research is needed. Importantly, ibandronate is the only bisphosphonate so far proven to reduce the risk of vertebral fractures significantly with a between-dose interval >2 months, in a prospective clinical trial. Collectively, the preclinical studies on ibandronate have provided a sound basis for the design of the convenient regimens currently being examined in clinical trials.

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.

The use of zoledronic acid in the management of metastatic bone disease and hypercalcaemia

Zoledronic acid is a potent, third generation, nitrogen-containing bisphosphonate, licensed for the management of skeletal metastases and hypercalcaemia of malignancy, both of which cause considerable morbidity. In the preclinical setting, zoledronic acid has demonstrated superior potency regarding inhibition of osteolysis and reduction of hypercalcaemia as compared with other bisphosphonates. Clinical trials have indicated that zoledronic acid is superior to pamidronate in suppressing osteolysis and in reducing hypercalcaemia of malignancy. Its main mechanism of action is induction of osteoclast apoptosis through inhibition of the mevalonate pathway. Zoledronic acid has also demonstrated direct anti-tumour activity both in vitro and in animal models, suggesting it may be of benefit in preventing the formation of bone metastases. Clinical trials are in progress, assessing the benefit of zoledronic acid in the adjuvant setting in both breast and prostate cancer.

Intravenous ibandronate reduces the incidence of skeletal complications in patients with breast cancer and bone metastases

BACKGROUND

This phase III study compared the efficacy of the new potent bisphosphonate, ibandronate, with placebo as intravenous (i.v.) therapy in metastatic bone disease due to breast cancer.

PATIENTS AND METHODS

A total of 466 patients were randomised to receive placebo (n = 158), or 2 mg (n = 154) or 6 mg (n = 154) ibandronate every 3-4 weeks for up to 2 years. The primary efficacy parameter was the number of 12-week periods with new bone complications, expressed as the skeletal morbidity period rate (SMPR). Bone pain, analgesic use and safety were evaluated monthly. Results SMPR was lower in both ibandronate groups compared with the placebo group; the difference was statistically significant for the ibandronate 6 mg group (P = 0.004 versus placebo). Consistent with the SMPR, ibandronate 6 mg significantly reduced the number of new bone events (by 38%) and increased time to first new bone event. Patients on ibandronate 6 mg also experienced decreased bone pain scores and analgesic use. Treatment with ibandronate was well tolerated.

CONCLUSIONS

These results indicate that 6 mg i.v. ibandronate is effective and safe in the treatment of bone metastases from breast cancer.

Intravenous ibandronate in men with osteoporosis: an open pilot study over 2 years

In the treatment of osteoporosis, the tolerance of oral bisphosphonates is often low. The high potency of ibandronate allows iv bolus injections that can be repeated every 2 to 3 months. However, the best dose and time interval of the treatment with iv ibandronate is still debated. Efficacy of 2-mg ibandronate injected every 3 months was tested in men with osteoporosis over 2 yr, in a prospective, open study. Fourteen men with primary osteoporosis, mean age 57 +/- 12 yr (range: 40-73), received 2-mg ibandronate iv every 3 months over 2 yr. All got 1 g/day calcium and 880 UI/day vitamin D for 2 yr. Bone mineral density (BMD) increased after 2 yr by 6.7 +/- 1.5% (mean change +/- SEM) at lumbar spine (p<0.001), by 3.2 +/- 08% at trochanter (p<0.001) and by 1.4 +/- 1.1% at femoral neck (ns). Serum beta-crosslaps and osteocalcin decreased significantly by 30-45 and 30%, respectively, during the 2 yr of treatment. Serum calcium increased from the lower to the middle tertile of the normal range during the 2 yr of the study. The observed decrease of bone remodelling and the increase of BMD are of the same magnitude as those described with oral bisphosphonates. The increase of plasma calcium confirms the positive effect of the supplementation with calcium and vitamin D. These results suggest that 3 months are a good interval between two doses of iv ibandronate, when 2 mg are given.

Injectable bisphosphonates in the treatment of postmenopausal osteoporosis

Osteoporosis is a "silent" disease and the patient has usually no clue of it until the occurrence of a fragility fracture. Prevention requires a continuous daily treatment that could be uncomfortable to the patient. Besides the recently introduced weekly oral schedules, injectable bisphosphonates have often been used as an off-label option to ameliorate compliance. In general, although with different efficiency, almost all injectable bisphosphonates can improve bone mineral density and suppress bone resorption markers. The effect of intravenous infusions of bisphosphonates are, to a large extent, similar to equivalent intramuscular administrations, but doses and dosing intervals represent the critical issues. Pain at the injection site and acute phase reactions are relatively common to intramuscular clodronate and intravenous infusions of nitrogen-containing bisphosphonates, respectively. Under certain circumstances, intermittent treatment with injectable bisphosphonates might represent a feasible alternative when compliance is at risk.

Efficacy and safety of ibandronate in the treatment of hypercalcemia of malignancy: a randomized multicentric comparison to pamidronate

GOALS

To compare the efficacy and safety of ibandronate and pamidronate in patients with hypercalcemia of malignancy (HCM).

PATIENTS AND METHODS

Seventy-two patients with HCM [albumin-corrected serum calcium (CSC) >2.7 mmol/l] were treated with a single infusion of ibandronate (2 or 4 mg) or pamidronate (15, 30, 60, or 90 mg) on day 0. The dose was dependent on the severity of hypercalcemia (baseline CSC level). CSC was assessed daily until day 4, then at intervals until day 28. The primary endpoint was lowering of CSC at day 4. Secondary endpoints included the number of patients responding and time to re-increase following response.

MAIN RESULTS

Using the CSC baseline approach, the most frequently administered doses were 4 mg ibandronate (78.4%) and 60 mg pamidronate (50.0%). Mean lowering of CSC at day 4 was 0.6 mmol/l for ibandronate and 0.41 mmol/l for pamidronate. The 95% confidence interval for the difference ibandronate pamidronate had a lower limit of 0.05 mmol/l, indicating that ibandronate was as effective as pamidronate. The number of patients responding to the two agents was also similar; 76.5% of ibandronate patients and 75.8% of pamidronate patients were rated as responders after the first dose of study medication. The median time to re-increase after response was longer for ibandronate (14 days) than pamidronate (4 days) ( P=0.0303). In the subgroup of 17 patients with high baseline CSC (>3.5 mmol/l), ibandronate appeared to be more effective than pamidronate. The safety profile of both agents was similar.

CONCLUSIONS

Ibandronate is at least as effective as pamidronate in the treatment of HCM. Furthermore, in patients with higher baseline CSC ibandronate appears to be more effective than pamidronate. The duration of response is significantly longer with ibandronate than pamidronate.

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.

Treatment of tumor-induced hypercalcemia: a solved problem?

Less than 25 years ago, tumor-induced hypercalcemia was often a lethal complication of cancer. Nowadays, it can be successfully and easily treated in at least 90% of the cases by rehydration and potent antiosteoclastic bisphosphonates. The standard therapy consists of the administration of 90 mg of pamidronate (Aredia Dry Powder) or more recently, 4 mg of zoledronic acid (Zometa)], which is even more efficient, at least in patients without bone metastases. Recurrent hypercalcemia is nevertheless difficult to control and antibodies against parathyroid-hormone-related protein may prove to be a useful treatment.

Zoledronic acid: an advance in tumour bone disease therapy and a new hope for osteoporosis

The two main therapeutic applications of bisphosphonates are tumour bone disease and osteoporosis. They constitute the standard treatment for cancer hypercalcaemia, and placebo-controlled trials have shown that the prolonged administration of bisphosphonates, such as pamidronate or clodronate, can reduce the frequency of complications from tumour bone disease due to metastatic breast cancer or myeloma by a quarter to one-half. The results obtained with the intravenous route appear to be more impressive and more rapidly obtained than with oral compounds. Both agents can reduce the risk of vertebral, wrist and hip fractures by 30 - 50%, whereas other antiresorptive agents, such as raloxifene (Eli Lilly & Co.) or calcitonin (Unigene Laboratories Inc.), have only been demonstrated to reduce the incidence of vertebral fractures. The short infusion time (4 mg over 15 min) offers a convenient therapy and constitutes the most evident advantage of zoledronic acid, which will improve patients' quality of life. Zoledronic acid has the potential to change the treatment of osteoporosis dramatically.

Ibandronate in the treatment of prostate cancer associated painful osseous metastases

The aim of our study was to assess the clinical efficacy and toxicity of ibandronate in the management of symptomatic skeletal metastases due to prostate cancer (PCA). Twenty-five patients with painful osseous metastases due to hormone refractory PCA (HRPCA) were treated with 6 mg ibandronate every 4 weeks in an open prospective non-randomized clinical study. Primary study endpoint was pain reduction documented by the use of a 10-point visual analog scale. Palliative response with significant reduction in pain score from 6.5 (5-10) to 2.0 [(0-4), P<0.001] was achieved in 23 (92%) patients; nine patients (39%) were completely pain free. Bisphosphonate treatment of painful osseous metastases due to HRPCA resulted in a significant pain reduction and a significant decrease of daily consumption of analgesics in 92% of the patients. Both characteristics are paralleled by an increase in Karnofsky index mainly due to better mobility. Bisphosphonates should have a definite role in the palliative management of symptomatic HRPCA.

The use of zoledronic acid, a novel, highly potent bisphosphonate, for the treatment of hypercalcemia of malignancy

BACKGROUND

Hypercalcemia of malignancy is a serious complication of cancer that affects patients with and without bone metastases. A single infusion of pamidronate disodium, a nitrogen-containing bisphosphonate, effectively normalizes serum calcium in the majority of patients treated for up to 1 month. Zoledronic acid is a new-generation, heterocyclic nitrogen-containing bisphosphonate and the most potent inhibitor of bone resorption identified to date.

METHODS

The natural history, clinical presentation, and treatment of hypercalcemia of malignancy are reviewed, with a focus on the mechanisms of action and relative efficacy and safety of bisphosphonate therapies.

RESULTS

The improved efficacy of zoledronic acid compared with pamidronate disodium has been demonstrated in a pooled analysis of two randomized clinical trials in patients with hypercalcemia of malignancy. In these trials, both zoledronic acid and pamidronate disodium were safe and well tolerated; however, zoledronic acid treatment resulted in a significantly higher number of complete responses, more rapid calcium normalization, and more durable responses compared with pamidronate disodium.

CONCLUSIONS

Given the superior efficacy and comparable safety profile of zoledronic acid compared with pamidronate disodium, zoledronic acid is likely to become the treatment of choice for hypercalcemia of malignancy.

Renal Safety of Intravenous Ibandronic Acid in Breast Cancer Patients with Metastatic Bone Disease

INTRODUCTION

Renal adverse events are a troublesome complication of bisphosphonate therapy. This study investigated the effect of intravenous ibandronic acid (ibandronate) treatment on renal function in breast cancer patients with metastatic bone disease.

METHODS

74 patients were randomised to double-blind (but not dose-blind) treatment with bolus injections of ibandronic acid 2mg (n = 23), 1-hour infusions of ibandronic acid 6mg (n = 28), or placebo injections or infusions (n = 23). According to randomisation, patients received either three injections or three infusions over the 3-month period, one at the start and two subsequent doses at 4-weekly intervals. Measurements of urinary excretion of total protein, albumin, alpha(1)-microglobulin, N-acetyl-beta-D-glucosaminidase, haematuria and serum creatinine were performed before, during and after treatment.

RESULTS

Treatment with ibandronic acid was not associated with impairment of renal function; the renal safety profiles of ibandronic acid 2 and 6mg were similar to that of placebo. Assessments of proteinuria, haematuria, enzymuria and serum creatinine indicated that there were no statistically significant changes between pre- and post-treatment levels in patients receiving ibandronic acid 2 or 6mg or between patients receiving ibandronic acid or placebo. Urine parameters varied during treatment in the same range with approximately similar frequency in the ibandronic acid and placebo groups.

CONCLUSIONS

Short-term administration of intravenous ibandronic acid did not impair renal function in breast cancer patients with metastatic bone disease. Because tolerability profiles vary between bisphosphonates, the lack of renal toxicity with ibandronic acid makes the drug an attractive treatment option for metastatic bone disease.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Bisphosphonate therapy in multiple myeloma: past, present, future

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

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.