Efficacy and safety of the bisphosphonate tiludronate for the treatment of tumor-associated hypercalcemia

DrugNet: network-based drug-disease prioritization by integrating heterogeneous data

OBJECTIVE

Computational drug repositioning can lead to a considerable reduction in cost and time in any drug development process. Recent approaches have addressed the network-based nature of biological information for performing complex prioritization tasks. In this work, we propose a new methodology based on heterogeneous network prioritization that can aid researchers in the drug repositioning process.

METHODS

We have developed DrugNet, a new methodology for drug-disease and disease-drug prioritization. Our approach is based on a network-based prioritization method called ProphNet which has recently been developed by the authors. ProphNet is able to integrate data from complex networks involving a wide range of types of elements and interactions. In this work, we built a network of interconnected drugs, proteins and diseases and applied DrugNet to different types of tests for drug repositioning.

RESULTS

We tested the performance of our approach on different validation tests, including cross validation and tests based on real clinical trials. DrugNet achieved a mean AUC value of 0.9552±0.0015 in 5-fold cross validation tests, and a mean AUC value of 0.8364 for tests based on recent clinical trials (phases 0-4) not present in our data. These results suggest that DrugNet could be very useful for discovering new drug uses. We also studied specific cases of particular interest, proving the benefits of heterogeneous data integration in this problem.

CONCLUSIONS

Our methodology suggests that new drugs can be repositioned by generating ranked lists of drugs based on a given disease query or vice versa. Our study shows that the simultaneous integration of information about diseases, drugs and targets can lead to a significant improvement in drug repositioning tasks. DrugNet is available as a web tool from http://genome2.ugr.es/drugnet/ (accessed 23.09.14). Matlab source code is also available on the website.

Nephrotic syndrome after oral bisphosphonate (alendronate) administration in a patient with osteoporosis

Alendronate is a widely used bisphosphonate in the treatment of osteoporosis. Although it has been proven to be a very useful drug, it has some side effects as well. In this paper, we describe a case of nephrotic syndrome due to alendronate administration. A 36-year-old man was admitted to the nephrology outpatient clinic with widespread edema 4 months after initiation of alendronate. He had a 13-kg weight gain within a 2-week period. He had no clinical or laboratory problems apart from osteoporosis, which was the indication for initiation of the drug. Physical examination at admission was unremarkable, but for nephrotic edema. Laboratory studies revealed nephrotic range proteinuria (13.5 g/day), normal renal function, hypoalbuminemia (1.7 g/dl), and also hypercholesterolemia (400 mg/dl). A kidney biopsy was performed. Light microscopic evaluation revealed a slight increase in mesangial cells and matrix; however, no abnormalities in the tubules or interstitium were noted. Alendronate was withdrawn and diuretic therapy was initiated. Patient's weight gradually decreased from 84 to 67 kg within a 1-week period. No other drugs for the treatment of nephrotic syndrome were administered. During the clinical course, serum creatinine remained stable, and proteinuria gradually decreased and disappeared 40 days after stopping alendronate. It was noted that alendronate administration can give rise to nephrotic syndrome, while discontinuation of this drug may improve the pathology without any specific treatment.

The kidney and bisphosphonates

Bisphosphonates are eliminated from the human body by the kidney. Renal clearance is both by glomerular filtration and proximal tubular secretion. Bisphosphonates given rapidly in high doses in animal models have induced a variety of adverse renal effects, from glomerular sclerosis to acute tubular necrosis. Nevertheless in the doses that are registered for the management of postmenopausal osteoporosis (PMO), oral bisphosphonates have never been shown to adversely affect the kidney, even (in post-hoc analysis of clinical trial data) down to estimated glomerular filtration rates of 15 ml/min. In addition fracture risk reduction has also been observed in these populations with stage 4 chronic kidney disease (CKD) with age-related reductions in glomerular filtration rate (GFR). Intravenous zoledronic acid is safe when the infusion rate is no faster than 15 min though there have been short-term (days 9-11 post-infusion) increases in serum creatinine concentrations in a small sub-set of patients from the postmenopausal registration trials. For these reasons intravenous zoledronic acid should be avoided in patients with GFR levels <35 ml/min; and the patients should be well hydrated and have avoided the concomitant use of any agent that may impair renal function. Intravenous ibandronate has not to date been reported to induce acute changes in serum creatinine concentrations in the PMO clinical trial data, but the lack of head-to-head comparative data between ibandronate and zoledronic acid precludes knowing if one intravenous bisphosphonate is safer than the other. In patients with GFR levels <30-35 ml/min, the correct diagnosis of osteoporosis becomes more complex since other forms of renal bone disease, which require different management strategies than osteoporosis, need to be excluded before the assumption can be made that fractures and/or low bone mass are due to osteoporosis. In addition, in patients who may have pre-existing adynamic renal bone disease, there is a lack of evidence of any beneficial effect or harm by reducing bone turnover by any pharmacological agent, including bisphosphonates on bone strength or vascular calcification. Bisphosphonates are safe and effective for the management of osteoporosis when used in the right dose and in the right patient population for the right duration.

High incidence of hypocalcemia and serum creatinine increase in patients with bone metastases treated with zoledronic acid

BACKGROUND

Zoledronic acid belongs to the new generation of bisphosphonates with demonstrated clinical benefit for the treatment of bone metastases from different kinds of neoplasms. Hypocalcemia and serum creatinine elevation are expected adverse events during this therapy. The monitoring of serum calcium and creatinine is therefore recommended. The primary aim of this study was to establish the actual incidence of hypocalcemia and serum creatinine elevation during treatment with zoledronic acid. Skeletal-related events and side effects were also assessed.

METHODS

Serum creatinine and calcium levels were evaluated in 240 consecutive patients (83 males, 157 females; mean age, 62 years) with metastatic bone lesions from different solid tumors treated with zoledronic acid.

RESULTS

Overall, 93 of 240 patients (38.8%) developed hypocalcemia, which was grade (G)1 in 45 patients (48.4%), G2 in 37 patients (39.8%), G3 in 10 patients (10.8%), and G4 in one patient (1.1%). The median time to occurrence of hypocalcemia (any grade) was 2.3 months after the beginning of the treatment (range, 0-34.9 months). Increased serum creatinine was observed in 33 of 240 patients (13.7%), of whom 19 had G1 (57.6%), 11 had G2 (33.3%), and three had G3 (9.1%). The median time to serum creatinine increase (for any grade) was 4.7 months (range, 0-29.2 months).

CONCLUSIONS

Our analysis shows a high incidence of hypocalcemia and increased serum creatinine level during treatment with zoledronic acid. These results strongly support the need for accurate monitoring of plasma calcium and creatinine levels.

Safety of bisphosphonates in the treatment of osteoporosis

In this review 4 experts consider the major safety concerns relating to bisphosphonate therapy for osteoporosis. Specific topics covered are skeletal safety (particularly with respect to atypical fractures and delayed healing), gastrointestinal intolerance, hypocalcemia, acute-phase (i.e., postdose) reactions, chronic musculoskeletal pain, renal safety, and cardiovascular safety (specifically, atrial fibrillation).

Randomized, active-controlled study of once-weekly alendronate 280 mg high dose oral buffered solution for treatment of Paget's disease

Daily oral tablet bisphosphonate therapy for Paget's disease of bone may cause serious upper gastrointestinal adverse events. A once-weekly alendronate 280 mg oral buffered solution was compared with an alendronate 40 mg/day tablet. While both were similarly effective, the tablet appeared to be better tolerated in this study.

INTRODUCTION

Although daily doses of oral bisphosphonates are a generally safe and effective treatment for Paget's disease of bone (PDB), some patients may experience upper gastrointestinal adverse events (UGI AEs) or find the dosing requirements inconvenient and become noncompliant. A once-weekly (OW) oral dose of bisphosphonate in buffered solution (OBS) may be as effective, better tolerated, and more convenient.

METHODS

Sixty-three patients were randomized to either alendronate (ALN) 280 mg OW OBS (n = 42) or an ALN 40 mg/day tablet (n = 21) during a 6-month, randomized, double-blind, active-controlled trial. The primary endpoint was the mean percent decrease in total serum alkaline phosphatase (total ALP) from baseline at 6 months.

RESULTS

There were no significant differences in total ALP between groups during the 6-month period. There was a higher incidence of clinical AEs in the ALN 280 mg OW OBS (79%) vs. the ALN 40 mg/day tablet group (67%), including drug related AEs (48% and 10%, respectively), which led to study discontinuation (19.0% and 10%, respectively).

CONCLUSIONS

Although ALN 280 mg OW OBS was similarly effective as ALN 40 mg/day in reducing total ALP in patients with PDB, the ALN 40 mg/day tablet appears to be better tolerated than ALN 280 mg OW OBS.

Quarterly intravenous injection of ibandronate to treat osteoporosis in postmenopausal women

Osteoporosis is a chronic condition that generally requires long-term therapy for fracture risk reduction to become apparent. Although the bisphosphonates have made a major contribution to how clinicians manage osteoporosis, compliance with therapy has generally been less in the real-world setting than seen in clinical trials. Less-frequently administered dosage regimens or nonoral routes may enhance compliance and so maximize the therapeutic benefit of bisphosphonates. Ibandronate is a nitrogen-containing bisphosphonate, whose high potency allows it to be administered orally or intravenously with extended dosing intervals. This paper will review the role of intravenous ibandronate in the treatment of postmenopausal osteoporosis.

Renal safety of intravenous bisphosphonates in the treatment of osteoporosis

Oral bisphosphonates are the mainstay of treatment for osteoporosis but cannot be used in some patients due to gastrointestinal contraindications, gastrointestinal intolerance, malabsorption or the inability to comply with dosing requirements. In such patients, intravenous bisphosphonates are a useful alternative. This review summarises the renal safety issues associated with the use of intravenous bisphosphonates for osteoporosis. Intravenous bisphosphonates are generally well tolerated, which may be a reflection of their selective activity in bone and metabolic stability. Adverse effects on renal function are primarily related to infusion rate and dose. Due to lack of data, no conclusions can be made regarding bisphosphonate safety in patients with intrinsic renal disease or an estimated glomerular filtration rate of < 30 ml/min.

Collapsing focal segmental glomerulosclerosis in a liver transplant recipient on alendronate

We describe a case of collapsing focal segmental glomerulosclerosis and severe kidney dysfunction in a liver transplant recipient after the initiation of alendronate for osteopenia. In view of the increasing incidence of chronic kidney disease in long-term liver transplant patients, bisphosphonates need to be used with caution in these patients. The usefulness of bisphosphonates for the prevention of early bone loss after liver transplantation is increasingly reported. However, there is little information on the safety and efficacy of these drugs when used in the later stages of liver transplant, particularly in the presence of chronic kidney disease. Bisphosphonates are excreted unchanged via the kidneys after reaching the systemic circulation. Some cases of severe kidney injury, in particular collapsing focal segmental glomerulosclerosis, have been described that are associated with the use of pamidronate. Alendronate, a widely used bisphosphonate in transplant patients, has not been related to kidney toxicity. We describe a case of collapsing focal segmental glomerulosclerosis and severe kidney dysfunction in a liver transplant recipient soon after the initiation of alendronate for osteopenia. Possible pathogenetic mechanisms are discussed. In view of the increasing incidence of chronic kidney disease in long-term liver transplant patients, bisphosphonate need to be used with caution in patients with a low glomerular filtration rate.

Advances in the management of corticosteroid-induced osteoporosis with bisphosphonates

Corticosteroids are widely used as anti-inflammatory and immunosuppressive agents to treat a variety of chronic conditions. Long-term (>1 year) corticosteroid use can lead to bone loss, and therefore, osteopenia or osteoporosis. Corticosteroid-induced osteoporosis (CIO) leads to increased bone fragility and subsequently fractures, which, in turn, lead to a loss of physical, emotional and social health for the patient and increased costs for healthcare providers. A wealth of data exists demonstrating the efficacy of the oral bisphosphonates, etidronate, alendronate and risedronate in increasing bone mineral density in patients with CIO or preventing bone loss in patients commencing corticosteroid therapy. Data regarding fracture prevention are less clear, as statistically significant reductions in the incidence of fractures have only been reported for patient subgroups or meta-analyses. However, many treatment guidelines recommend the use of oral bisphosphonates for the prevention and treatment of CIO. These guidelines are, however, not reflected in prescribing practice, and the majority of patients do not receive adequate concomitant therapy. This review summarizes the available data for bisphosphonates in CIO. Therapeutic adherence with oral bisphosphonates is an issue, with approximately 50% of patients discontinuing therapy within the first year. The primary reasons for this are poor gastrointestinal tolerability and the frequency with which complex dosing requirements must be followed. The inconvenience of taking daily or weekly bisphosphonate therapy is of particular importance in patients with CIO who may be regularly taking several other medications. Data obtained in studies with ibandronate indicate that bisphosphonate administration by rapid intravenous injection provides an effective, well-tolerated and practical alternative to current oral regimens in the management of patients with CIO.

HEMATOLOGY: ISSUES IN THE DIALYSIS PATIENT: Multiple Myeloma in End-Stage Renal Disease

Multiple myeloma is a common cause of chronic kidney disease (CKD). Patients with myeloma-related kidney disease but low levels of serum monoclonal proteins can be diagnosed with symptomatic myeloma in a simplified diagnostic classification. The presence and type of renal disease in myeloma is dependent on the light chain secreted. Treatment has recently changed and now includes the use of thalidomide and bisphosphonates. Thalidomide can cause hyperkalemia and bisphosphonates can cause renal failure in patients with CKD. Their use is not contraindicated, but they should be used with caution. High-dose melphalan with an autologous stem cell transplant is now the standard of care and should not be withheld from patients with CKD, even those on dialysis. This treatment can improve the renal disease, and this is more likely if treatment is started early. In patients with persistent dialysis dependence, renal transplantation can be performed if the patient has a complete remission.

Renal safety and efficacy of i.v. bisphosphonates in patients with skeletal metastases treated for up to 10 Years

INTRODUCTION

Bisphosphonates (BPs) delay the onset or reduce the incidence of skeletal complications in patients with bone metastases. However, there are few data on the renal safety and activity of i.v. BPs beyond 2 years of administration.

MATERIALS AND METHODS

We retrospectively analyzed serum creatinine (SCr) levels and skeletal-related events (SREs) in cancer patients receiving i.v. BPs for >or= 24 months. All patients received 90 mg pamidronate every 3-4 weeks. Pre- and post-treatment SCr levels and the peak levels attained were recorded. A notable SCr increase was defined as: an increase >0.5 mg/dl for patients with baseline SCr <1.4 mg/dl; an increase >1 mg/dl for patients with baseline SCr >1.4 mg/dl; or doubling over baseline. The following parameters were also analyzed: the proportion of patients with at least one SRE, the distribution of each type of SRE, the time to first SRE, and the skeletal morbidity rate (SMR).

RESULTS

Fifty-seven patients with bone metastases resulting from breast cancer (BC) (n = 48), multiple myeloma (n = 7), renal cell carcinoma (n = 1), and prostate cancer (n = 1) were evaluated. The median age at the start of treatment was 57 years (range, 27-81); 25% of the patients were >70 years old. Forty-three patients received pamidronate then switched to zoledronic acid. The median overall duration of BP administration was 34 months (range, 24+ to 131+), with a median duration of zoledronic acid therapy of 25 months (range, 2-40). Twenty-seven of 48 BC patients received different chemotherapy regimens (median number of lines, 2; range, 1-6). The median SCr levels were: baseline, 0.82 mg/dl (range, 0.4-1.4); time of analysis, 0.89 mg/dl (0.4-2); highest level, 1.0 mg/dl (0.5-2). A notable SCr increase was observed in seven patients (12.2%; all grade 1). Twenty-six patients (45.6%) experienced SREs after starting BP treatment. The median time to first SRE was 911 days (95% confidence interval, 731; 1,023). The SMR was 0.20 events per year. Ten patients ceased treatment because of: an SCr level of 2 mg/dl (n = 1) physician decision (n = 6) and jaw osteonecrosis (n = 3). Ten patients died of progressive disease.

CONCLUSION

i.v. BPs are safe and active during prolonged treatment administration, and renal function is maintained in patients receiving multiple cytotoxic therapies. Jaw osteonecrosis occurred in 5% of the study population, and its causal relationship with BP treatment requires further observation and study.

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.

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.

Podocyte injury associated glomerulopathies induced by pamidronate

BACKGROUND

Pamidronate has been demonstrated to decrease bone-related complications in multiple myeloma and delay progression of the disease. This has led to its use in supportive and maintenance therapy of myeloma in conjunction with steroids and chemotherapy. It has also been selectively used in patients with breast cancer and other neoplasms.

METHODS

We report on five patients who developed glomerular disease induced by pamidronate. Pamidronate was the only drug common to all patients. Tests for hepatitis B and C and human immunodeficiency virus (HIV) were negative for all patients. The first two patients received a high dose of pamidronate for 8 weeks, whereas the other three patients were on monthly therapy for a prolonged period of time. Sources of data included chart review and pathologic analysis of kidney biopsy.

RESULTS

Three patients were female and two were males and all were Caucasian, ranging in age from 58 to 71 years. Renal biopsy findings included minimal change disease in two, focal segmental glomerulosclerosis in two, and collapsing focal segmental glomerulosclerosis in one. Immunofluorescence was essentially negative in all cases. Electron microscopy showed variable podocyte injury and extensive foot process effacement. There was no evidence of multiple myeloma-related renal disease. After the biopsy, pamidronate was discontinued and renal function stabilized in all patients except the one with the collapsing variant of focal segmental glomerulosclerosis who required hemodialysis. Three patients had resolution of proteinuria, one patient continued to have proteinuria without deterioration in renal function.

CONCLUSION

Pamidronate has been mainly associated with collapsing focal segmental glomerulosclerosis. This report expands that relationship and adds other glomerular diseases linked with podocyte injury. Additional studies are needed to define the cause of the variability of renal histology with this agent.

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.

Efficacy and safety of ibandronate given by intravenous injection once every 3 months

Oral bisphosphonates are established therapeutics for postmenopausal osteoporosis. Alternative, simplified dosing regimens that improve tolerability and promote convenience may be advantageous. Ibandronate is a highly potent, nitrogen-containing bisphosphonate that can be administered as a convenient intravenous (i.v.) injection (over 15-30 s) in schedules featuring extended between-dose intervals. In a recent fracture prevention study, 1 and 0.5 mg i.v. ibandronate injections, given once every 3 months, were shown to dose-dependently increase lumbar spine and hip bone mineral density (BMD) and decrease biochemical markers of bone turnover in women with postmenopausal osteoporosis, but the overall magnitude of efficacy provided by both doses was suboptimal. In the present study (Intermittent Regimen intravenous Ibandronate Study: the IRIS study), the dose-response relationship with intermittent intravenous ibandronate injections was further evaluated in 520 postmenopausal osteoporotic women (aged 55-75 years, time since menopause >or= 5 years, lumbar spine [L1-L4] BMD T score < -2.5). At enrolment, participants were randomized to receive either 2 mg (n = 261) or 1 mg (n = 131) ibandronate or placebo (n = 128) intravenous injections, given once every 3 months. After 1 year, ibandronate therapy produced substantial and dose-dependent increases in lumbar spine and hip BMD, and decreases in biochemical markers of bone turnover, with the 2 mg dose providing significantly greater efficacy than the 1 mg dose. Most notably, lumbar spine BMD increased by 5.0% and 2.8% in the 2 and 1 mg groups, respectively, and decreased by 0.04% in the placebo group. Furthermore, total hip BMD increased by 2.9%, 2.2%, and 0.6%, respectively. Serum and urinary CTX, reflecting bone resorption, were decreased by 62.5% and 61%, respectively, with the 2 mg dose, and by 43.5% and 42%, respectively, with the 1 mg dose. Intravenous ibandronate was well tolerated with a similar incidence of adverse events to placebo. Importantly, no indicators of renal toxicity were reported. In summary, the 2 mg ibandronate regimen provides significantly greater BMD increases and significantly greater suppression of bone resorption markers than the 1 mg dose used in this study and in the previous fracture prevention study. Ongoing studies aim to further establish the efficacy and convenience of intermittent intravenous ibandronate injections in postmenopausal osteoporosis.

Insufficiently dosed intravenous ibandronate injections are associated with suboptimal antifracture efficacy in postmenopausal osteoporosis

Less frequent bisphosphonate dosing in women with postmenopausal osteoporosis has the potential to promote therapy adherence through improved convenience. Ibandronate is a highly potent nitrogen-containing bisphosphonate, proven to significantly increase vertebral and nonvertebral bone mineral density (BMD) when administered as a convenient intravenous injection. A recent double-blind, placebo-controlled, randomized phase III study explored the antifracture efficacy and safety of 1 and 0.5 mg iv ibandronate injections, given once every 3 months, in 2862 women (55-76 years) with postmenopausal osteoporosis [one to four prevalent vertebral fractures and lumbar spine (L1-L4) BMD T score of less than -2.0 and greater than -5.0 in >or=1 vertebra]. All participants received daily vitamin D (400 IU) and calcium (500 mg) supplementation. The primary endpoint was the incidence of new morphometric vertebral fractures after 3 years. However, although a consistent trend toward a reduction in the incidence of new morphometric vertebral fracture was observed in the active treatment arms compared with placebo (9.2% vs. 8.7% vs. 10.7% in the 1 mg, 0.5 mg and placebo groups, respectively), as well as in the incidence of nonvertebral and hip fractures, the magnitude of fracture reduction was suboptimal and was insufficient to achieve statistical significance. At the studied doses, intravenous ibandronate injections also produced dose-dependent, but comparatively small, increases in lumbar spine BMD (4.0% and 2.9%, respectively) and decreases in biochemical markers of bone resorption and formation, relative to placebo. Optimal fracture efficacy likely requires more substantial increases in BMD and more pronounced suppression of bone turnover. In light of the clear dose-response relationship observed in this and other studies, this is likely to be achieved with higher intravenous doses of ibandronate. The results of a recent phase II/III study (Intermittent Regimen Intravenous Ibandronate Study: the IRIS study) provide support for this hypothesis.

Toxic acute tubular necrosis following treatment with zoledronate (Zometa)

BACKGROUND

Renal failure and toxic acute tubular necrosis (ATN) may be seen following exposure to a variety of therapeutic agents. Zoledronate (Zometa) is a new, highly potent bisphosphonate used in the treatment of hypercalcemia of malignancy. We report the first clinical-pathologic study of nephrotoxicity associated with this agent.

METHODS

A cohort of six patients (four males and two females) with a mean age of 69.2 years received bisphosphonate therapy for multiple myeloma (five patients) or Paget's disease (one patient). In all patients, zoledronate was administered at a dose of 4 mg intravenously monthly, infused over at least 15 minutes, and the duration of therapy was mean 4.7 months (range, 3 to 9 months).

RESULTS

All patients developed renal failure with a rise in serum creatinine from a mean baseline level of 1.4 mg/dL to 3.4 mg/dL. Renal biopsy revealed toxic ATN, characterized by tubular cell degeneration, loss of brush border, and apoptosis. Immunohistochemical staining revealed a marked increase in cell cycle-engaged cells (Ki-67 positive) and derangement in tubular Na+,K+-ATPase expression. Importantly, although all patients had been treated with pamidronate prior to zoledronate, no biopsy exhibited the characteristic pattern of collapsing focal segmental glomerulosclerosis observed in pamidronate nephrotoxicity. Following renal biopsy, treatment with zoledronate was discontinued and all six patients had a subsequent improvement in renal function (mean final serum creatinine, 2.3 mg/dL at 1 to 4 months of follow-up).

CONCLUSION

The close temporal relationship between zoledronate administration and the onset of renal failure and the partial recovery of renal function following drug withdrawal strongly implicate this important and widely used agent in the development of toxic ATN.

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.

The pharmacokinetics and pharmacodynamics of zoledronic acid in cancer patients with varying degrees of renal function

An open-label pharmacokinetic and pharmacodynamic study of zoledronic acid (Zometa) was performed in 19 cancer patients with bone metastases and known, varying levels of renal function. Patients were stratified according to creatinine clearance (CLcr) into different groups of normal (CLcr > 80 mL/min), mildly (CLcr = 50-80 mL/min), or moderately/severely impaired (CLcr = 10-50 mL/min) renal function. Three intravenous infusions of 4 mg zoledronic acid were administered at 1-month intervals between doses. Plasma concentrations and amounts excreted in urine were determined in all subjects, and 4 patients were administered 14C-labeled zoledronic acid to assess excretion and distribution of drug in whole blood. In general, the drug was well tolerated by the patients. Mean area under the plasma concentration versus time curve and mean concentration immediately after cessation of drug infusion were lower, and mean amounts excreted in urine over 24 hours from start of infusion were higher in normal subjects than in those with impaired renal function (36% vs. 28% of excreted dose), although the differences were not significant. Furthermore, with repeated doses, there was no evidence of drug accumulation in plasma or changes in drug exposure in any of the groups, nor was there any evidence of changes in renal function status. Serum levels of markers of bone resorption (serum C-telopeptide and N-telopeptide) were noticeably reduced after each dose of zoledronic acid across all three renal groups. It was concluded that in patients with mildly to moderately reduced renal function, dosage adjustment of zoledronic acid is likely not necessary.

Effect of daily and intermittent use of ibandronate on bone mass and bone turnover in postmenopausal osteoporosis: a review of three phase II studies

BACKGROUND

Oral bisphosphonates are well established for the treatment and prevention of postmenopausal osteoporosis; however, they are poorly absorbed from the gastrointestinal (GI) tract and have been associated with GI adverse events. Thus, current dosing guidelines recommend that the patient not eat or lie down for at least 30 minutes after taking oral bisphosphonates, a requirement that is inconvenient and may be associated with reduced compliance. The drawbacks of these dosing requirements may be overcome either by reducing dosing frequency or by using alternative routes of administration.

OBJECTIVE

Ibandronate is a potent nitrogen-containing bisphosphonate that can be given orally or IV, daily or intermittently, with a between-dose interval of up to 3 months. This article presents the results of published Phase II trials of the efficacy and safety profile of oral and IV ibandronate administered daily or intermittently to postmenopausal women with low bone mass.

METHODS

MEDLINE was searched through January 2002 to identify all published Phase II clinical studies of oral and IV ibandronate in the treatment of post-menopausal osteoporosis.

RESULTS

In the 3 Phase II studies identified, marked reductions in biochemical markers of bone resorption (50%-70%) and bone formation (40%-50%) were seen to a similar and statistically significant extent with oral ibandronate 2.5 mg/d (P<0.001), oral ibandronate 20 mg QOD given for 12 doses at the start of each 3-monthly period (P<0.001), and injections of ibandronate 2 mg IV given every 3 months (P<0.01). All treatment regimens produced comparable significant increases in bone mineral density at the lumbar spine (P<0.01) and hip (P<0.05). Ibandronate was well tolerated when administered both orally and as an IV injection.

CONCLUSIONS

In these Phase II studies, oral or IV ibandronate, administered continuously or intermittently, reduced markers of bone turnover, significantly increased bone mineral density, and was well tolerated in the treatment of osteoporosis in postmenopausal women. The data from these studies provided the rationale for further investigation of ibandronate in larger longer-term Phase III studies evaluating its potential as an efficacious and flexible alternative to existing bisphosphonate regimens.

Modern Therapy for Paget??s Disease of Bone

There has been a dramatic change in the therapeutic approach to patients with Paget's disease of bone over the last 40 years. In the 1960s, only symptomatic therapy could be given, with control of pain the main objective. Analgesics and nonsteroidal anti-inflammatory drugs were the most commonly used agents. From 1968 onwards, antiosteoclastic agents became available, including calcitonin, plicamycin (mithramycin) and etidronate (etidronic acid), a first-generation bisphosphonate. Limitations with these agents, including potentially deleterious effects on bone mineralization with etidronate (etidronic acid), has cleared the way for increasingly potent second- and third-generation bisphosphonates, including clodronate (clodronic acid), pamidronate (pamidronic acid), alendronate (alendronic acid) and risedronate (risedronic acid). Even more potent bisphosphonates will become available in the near future. With the newer bisphosphonates, there is some hope for long-term remission (if not definitive healing) of pagetic lesions, as well as prevention of long-term complications in both symptomatic and asymptomatic patients. Thus, indications for therapy have been extended to include younger patients to prevent bone deformity of the limbs and skull, leading to secondary osteoarthritis, facial deformities and potentially to sarcoma transformation; as well as to elderly patients to prevent bone fragility, leading to fracture, and pagetic vascular steal syndromes. The increased potency and longer duration of action of newer bisphosphonates more than compensates for their marginally increased cost compared with older bisphosphonates.

Hypercalcaemia of melanoma: incidence, pathogenesis and therapy with bisphosphonates

Tumour-induced hypercalcaemia (TIH) is a frequent complication of advanced cancer but has been rarely reported in patients with malignant melanoma, and its pathogenesis remains unexplored. We studied eight patients with TIH and melanoma. We determined the incidence and pathogenesis of this complication and the effects of bisphosphonate therapy. The incidence of TIH in 751 patients with melanoma was 1.1%. All patients had liver and bone metastases at the time of hypercalcaemia. All patients had osteolytic lesions, most often multiple. The median survival was 30 days (range 4-136 days). After rehydration, the mean (+/- SEM) corrected calcium was 3.42 +/- 0.17 mmol/l. Parathyroid hormone levels were adequately suppressed and vitamin D concentrations were normal. Serum osteocalcin, a marker of bone formation, was low, except in the two patients with renal insufficiency, whereas fasting urinary calcium and hydroxyproline were increased, indicating inhibition of bone formation and stimulation of bone resorption. Increased parathyroid hormone-related protein secretion was noted in only one patient. Three of four patients became normocalcaemic after bisphosphonate therapy for a median duration of 2 weeks. In conclusion, hypercalcaemia is a rare complication of melanoma. It occurs in the context of far advanced disease and is essentially due to aggressive lytic bone metastases with an uncoupling in bone turnover. Bisphosphonates can offer short-term palliation.

Renal tolerability profile of novel, potent bisphosphonates in two short-term rat models

Bisphosphonates are used clinically to inhibit bone resorption but they may also cause renal damage. For the profiling of new potent bisphosphonates, their adverse renal effects were investigated in 2 rat models. In the first model, bisphosphonate was repeatedly injected (1 mg/kg, subcutaneously) over 2 weeks and the urinary excretion of malate dehydrogenase was monitored to assess nephrotoxic potential. Of the 6 new compounds tested, 3 markedly elevated malate dehydrogenase whereas 3 others caused only minor changes similar to those observed with 6 reference bisphosphonates that are already used clinically. On the basis of a therapeutic index (inhibition of bone resorption versus renal effects) 7-180 fold greater than that of other analogues, the compound CGP 42446 was further profiled. In the second model, CGP 42446 or pamidronate was infused (1.5-50 mg/kg, intravenously) into anaesthetized rats and the serum urea concentration was monitored as an indicator of renal dysfunction. Both compounds elevated serum urea in a time- and dose-dependent manner, but the ED100 value for CGP 42446 was 3.8-fold higher than that of pamidronate. It is concluded that CGP 42446 (zoledronate) has a low nephrotoxic potential and can be further developed as a new potent inhibitor of bone resorption.

A new human breast cancer cell line, KPL-3C, secretes parathyroid hormone-related protein and produces tumours associated with microcalcifications in nude mice

Parathyroid hormone-related protein (PTHrP) is the main cause of humoral hypercalcaemia of malignancy (HHM). We recently established a new human breast cancer cell line, designated KPL-3C, from the malignant effusion of a breast cancer patient with HHM. Morphological, cytogenetic and immunohistochemical analyses indicated that the cell line is derived from human breast cancer. The KPL-3C cells stably secrete immunoreactive PTHrP measured by a two-site immunoradiometric assay, possess both oestrogen and progesterone receptors and are tumorigenic in female nude mice. The addition of phorbol-12-myristate-13-acetate to the medium significantly increased PTHrP secretion from the cells. In contrast, hydrocortisone, medroxyprogesterone acetate and 22-oxacalcitriol decreased PTHrP secretion in a dose-dependent manner. Unexpectedly, a number of microcalcifications were observed in the transplanted tumours. Radiographical examination indicated that the microcalcifications in the tumours are very similar to those commonly observed in human breast cancer. These findings suggest that this KPL-3C cell line may be useful for studying the regulatory mechanisms of PTHrP secretion and the mechanisms that lead to the deposition of microcalcifications in breast cancer.

Administration of the bisphosphonate ibandronate (BM 21.0955) by intravenous bolus injection

Bisphosphonates (BPs) are used for the treatment of both benign and malignant diseases characterized by increased bone resorption. Because of their potential nephrotoxicity, currently available BPs have to be administered by slow intravenous infusion, with conventional doses requiring an infusion time of at least 2 h. In the present investigation, we evaluated the safety and efficacy of the new BP ibandronate as administered by intravenous bolus injection. On day 0, 15 normocalcemic breast cancer patients with bone metastases were treated with 3 mg of ibandronate injected intravenously over 60-120 s. Ibandronate treatment led to significant decreases in serum levels of calcium (p < 0.0001) and phosphate (p < 0.0001) and to subsequent increases in serum concentrations of parathyroid hormone (p <0.0001) and calcitriol (p <0.0001). Moreover, there was a significant reduction in the urinary excretion of calcium (p <0.0001), pyridinoline (p <0.001), and deoxypyridinoline (p < 0.0001). Three serious adverse events were observed: vomiting (WHO grade 3), pulmonary infection (WHO grade 2), and deterioration of a pre-existing impaired glucose tolerance (WHO grade 3). Only vomiting appeared to be related to administration of the drug. The most frequent nonserious adverse events were 10 cases of transient clinically asymptomatic hypocalcemia and 8 cases of asymptomatic hypophosphatemia. Serum levels of creatinine and urea nitrogen did not increase, nor did creatinine clearance deteriorate. When tested with the dipstick method, proteinuria was present in five (33%) patients prior to ibandronate treatment (median protein concentration, 30 mg/dl). Following the BP injection, seven (47%) patients showed slight (highest protein concentration, 30 mg/dl) transient proteinuria at at least one time point, of which six cases appeared in conjunction with leucocyturia and three with microhematuria. Side effects specific to aminosubstituted BPs (fever, reduction in white blood cell counts, and lymphocyte counts) were not seen in these 15 patients. In conclusion, a single intravenous injection of 3 mg of ibandronate significantly inhibited osteoclast activity as reflected by the decrease in serum calcium and in urinary parameters of bone resorption. Serum creatinine levels and estimates of creatinine clearance were not affected by therapy. However, before repeated bolus injections of ibandronate at this dosage can be recommended for further clinical trials, whether a relationship exists between the transient pathological urinary findings and injected ibandronate needs to be determined.

Tiludronate: bone pharmacology and safety

The pharmacological properties of tiludronate (4-chlorophenyl)thiomethylene bisphosphonate), a sulfured bisphosphonate, have been characterized in a series of preclinical in vivo and in vitro studies. In vivo, tiludronate exerts a dose-dependent inhibitory activity on bone resorption. This property was demonstrated in several animal models, including rats, ewes, and dogs, when bone resorption was induced by administration of retinoid acid or parathyroid hormone, or by immobilization, ovariectomy or orchidectomy. By uncoupling bone resorption from bone formation, tiludronate can induce a positive calcium and phosphate balance. When administered either continuously or intermittently to ovariectomized osteoporotic rats, tiludronate promotes a significant increase in bone mass. This positive effect is associated with an increase in mechanical resistance. Bone tolerance studies indicate that tiludronate is a safe compound with an appreciable therapeutic margin since it can effectively inhibit bone resorption without reducing bone mineralization and strength. In vitro, tiludronate added to bone tissue culture inhibits calcium release, lysosomal enzyme secretion and collagen matrix degradation when induced by various stimulators of bone resorption. At the cellular level, tiludronate does not appear to exert its inhibitory effect on bone resorption by impairing either the recruitment, the migration or the fusion of osteoclast precursors. Tiludronate could act on mature osteoclasts by reducing their capacity to secrete proton into the resorption space and also by favoring their detachment from the bone matrix. The available preclinical data indicate that tiludronate should be an efficacious bisphosphonate in the management of clinical conditions characterized by excessive bone resorption.

Intravenous pamidronate in patients with tumor-induced osteolysis: a biochemical dose-response study

Bisphosphonates are used increasingly in normocalcemic patients for treating tumor-induced osteolysis (TIO) but little is known about the metabolic effects and the most appropriate therapeutic regimen. In 21 patients with breast cancer and TIO, we determined the biochemical effects of a single infusion of pamidronate given at 30 mg (n = 5), 60 mg (n = 5), 90 mg (n = 5), or 120 mg (n = 6). Patients received no other systemic antineoplastic therapy during the trial. We selected patients with baseline fasting urinary Ca/Creat (creatinine) > 0.105 mg/mg (median value of our normal range) and they were followed weekly for up to 14 weeks. The biochemical effects were maximal at day 7. For the whole group, mean (+/- SEM) Ca/Creat levels fell from 0.208 +/- 0.018 to 0.048 +/- 0.008 mg/mg on day 7 and remained significantly ( p < 0.01) lower than baseline up to day 56. Hydroxyproline excretion fell to a lesser degree, from 7.0 +/- 1.2 to 4.0 +/- 0.6 mg x 100/mg of Creat. The falls in Ca/Creat and hydroxyproline excretion were dose-related (ANCOVA, p < 0.05). Changes in serum parameters of calcium metabolism were, however, not significantly dose-related. Serum Ca levels fell from 9.3 +/- 0.1 to 8.7 +/- 0.1 mg/dl on day 7, but not patients developed symptomatic hypocalcemia, and the decrease within each dose group was significant only at 120 mg. Ca2+ levels followed a similar pattern. There was a slight increase in Mg levels and a pronounced fall in Pi levels, from 3.6 +/- 0.2 to 2.8 +/- 0.1 mg/dl. Intact PTH levels increased from 29 +/- 4 to 91 +/- 13 pg/ml and remained significantly (p < 0.05) elevated up to day 28.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative prospective, double-blind, multicenter study of the efficacy of tiludronate and etidronate in the treatment of Paget's disease of bone

OBJECTIVE

To compare the efficacy and safety of tiludronate and etidronate at the same dosage (400 mg/day) for the treatment of active Paget's disease of bone.

METHODS

We studied 234 patients with radiologic lesions characteristic of Paget's disease of bone and serum alkaline phosphatase (AP) concentrations at least twice the upper limit of normal, in a prospective, randomized, double-blind, multicenter clinical trial lasting 6 months. Patients were randomly allocated into 1 of 3 treatment groups: tiludronate for 3 months followed by placebo for 3 months, tiludronate for 6 months, or etidronate for 6 months. Serum AP levels and urinary hydroxyproline excretion were measured at baseline and after 3 months and 6 months. Patients with a reduction of at least 50% in the serum AP concentration were considered to be responders.

RESULTS

After 3 months, the proportion of responders was higher in the tiludronate group (57.4%) than in the etidronate group (13.9%) (P < 0.0001). In the etidronate group, this percentage was lower among patients who had received previous treatment with a bisphosphonate (2.3%) than among those who had not (28.6%) (P < 0.01). Previous bisphosphonate treatment was not associated with response in the tiludronate group. After 6 months, the proportion of responders did not differ between the 2 tiludronate groups (60.3% and 70.1%), but was lower in the etidronate group (25.3%) (P < 0.0001). There was a higher proportion of patients with treatment-resistant disease (< 25% reduction of serum AP) in the etidronate group (51.9%) than in the tiludronate 3-month group (17.9%) or the tiludronate 6-month group (19.5%) (P < 0.0001). Gastrointestinal disturbances were more common, and occurred earlier, with tiludronate, but they were mostly mild, requiring no treatment.

CONCLUSION

Tiludronate at 400 mg/day for 3 months or 6 months is more effective than the same dosage of etidronate for 6 months in the treatment of Paget's disease.

Drugs used in the treatment of metabolic bone disease. Clinical pharmacology and therapeutic use

Osteoporosis is the most important metabolic bone disease and places an increasing burden on the healthcare system. The condition can be prevented by the early introduction of hormone replacement therapy. The role of bisphosphonates in achieving the same result is being actively explored. The attraction of preventing bone loss is that it preserves the micro-architecture of bone, and therefore its mechanical integrity. The great problem of treating the established condition is that substantial bone loss is accompanied by architectural disintegration. Replacing lost bone may not necessarily restore mechanical integrity and protect against fractures. The management of Paget's disease has been quite revolutionised by the introduction of the bisphosphonates. The condition is a result of a primary increase in osteoclastic bone resorption which can be corrected by bisphosphonates, with considerable symptomatic improvement. The increasing potency and safety margin of the newer agents has meant that the threshold for treatment has fallen. There is now potential for long term control of bone turnover with the hope of preventing late complications. Hypercalcaemia of malignancy is usually the result of both increased bone destruction and decreased urinary calcium excretion. These two components of hypercalcaemia demand different approaches to management. The general availability of an ever-expanding range of increasingly potent bisphosphonates has resulted in a dramatic improvement in the treatment of increased bone resorption associated with malignancy. Many types of tumour, either directly or indirectly, compromise the ability of the kidney to eliminate a calcium load derived from increased bone destruction. Calcitonin is the only agent which is currently available to counter this process.

Bisphosphonates in the treatment of metabolic bone diseases

Bisphosphonates (BP) are pyrophosphate analogs, P-C-P with various carbon side-chains. The phosphate groups are responsible for the low gastrointestinal absorption (about 1%), limited penetration into cells, adsorption to bone mineral and rapid excretion in the urine. Based on the C side-chains, BPs can inhibit osteoclastic bone resorption with potencies which differ by as much as 10,000-fold among compounds. The most potent inhibitors are aminobisphosphonates. Studies of the amino-BP alendronate show preferential uptake at sites of bone resorption where they block osteoclastic activity by inhibiting ruffled border formation. BPs are the treatment of choice for hypercalcaemia of malignancy, where a single infusion with a potent BP will normalize serum calcium in 80% of the patients. Paget's disease also shows an excellent long-term response to BPs. In addition, BPs are being studied for the treatment of osteoporosis and other bone disorders which could be helped by inhibition of bone resorption.

Circulating PTHrP concentrations in tumor-induced hypercalcemia: influence on the response to bisphosphonate and changes after therapy

We studied the influence of circulating parathyroid hormone-related protein (PTHrP) concentrations on the response of hypercalcemic cancer patients to bisphosphonate therapy. We also examined the changes in circulating PTHrP levels during the normalization of serum Ca to determine if part of the increase in PTHrP concentrations is not secondary to hypercalcemia itself, as suggested by some in vitro data. We sequentially measured in 45 hypercalcemic cancer patients treated by pamidronate the circulating concentrations of PTHrP (by an amino-terminal RIA; normal values < 9 pmol/liter), Ca, Ca2+, Pi, intact PTH, and the fasting urinary excretion of Ca (Ca/Cr) and cyclic AMP (cAMP). Mean +/- SEM baseline PTHrP levels were 9.5 +/- 1.3, with a median (range) value of 6.0 (< 3.4-43) pmol/liter. PTHrP levels were elevated in 18 of 45 patients, more often in epidermoid than in glandular carcinomas (P < 0.05), and they were significantly (P < 0.05) correlated with the concentrations of Pi (r = -0.46), Ca/Cr (r = -0.31), and urinary cAMP (r = 0.47). Mean pretreatment Ca levels were not significantly different between patients with elevated and patients with normal PTHrP levels, 13.3 +/- 0.4 versus 12.9 +/- 0.4 mg/dl, but the concentrations became significantly different (P < 0.005) 4 days after therapy, 10.2 +/- 0.3 versus 9.2 +/- 0.1 mg/dl, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Medical treatment of tumor-induced hypercalcemia and tumor-induced osteolysis: challenges for future research

Tumor-induced hypercalcemia (TIH) and tumor-induced osteolysis (TIO) are essentially due to a marked increase in osteoclast-mediated bone resorption. Parathyroid-hormone-like protein plays an essential role in TIH, and maybe in TIO, but other substances, such as growth factors or cytokines, could contribute to the osteoclast activation and osteoblast inhibition secondary to the neoplastic infiltration of the skeleton. Treatment of TIH essentially consists of volume repletion and administration of potent anti-osteolytic drugs. Intravenous administration of the bisphosphonate clodronate or pamidronate is particularly useful for this. Pamidronate at a dose of 1.0-1.5 mg/kg as a single 4- to 24-h infusion can normalize serum calcium in about 90% of hypercalcemic cancer patients. The apparently low response rate of bone metastases to systemic antineoplastic therapy seems essentially to reflect the relative insensitivity of our current methods for assessing response in TIO. Quantitative evaluation of pain and of newly developed biochemical markers of bone turnover could be particularly useful for early assessment of response. Prolonged administration of oral pamidronate could reduce by almost one-half the complications of TIO, and iterative bisphosphonate infusions could induce a dramatic relief of bone pain in one-third and a sclerosis of lytic lesions in one-fourth of the cases. These data must, however, be confirmed in randomized blind trials and many questions remain unanswered concerning the optimal therapeutic schemes. Despite these limitations, medical therapy of TIO by non-cytotoxic means has already become a reality.