Dose-response in the treatment of hypercalcemia of malignancy by a single infusion of the bisphosphonate AHPrBP

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.

De-escalated administration of bone-targeted agents in patients with breast and prostate cancer-A survey of Canadian oncologists

Objective

Questions remain regarding the optimal use of bone-targeted agents in patients with metastatic bone disease. The purpose of this study was to assess current clinical practice regarding the use and administration of bone-targeted agents by Canadian oncologists in patients with metastatic breast and prostate cancer.

Methods

A survey was designed to explore; bone-targeted agent use in metastatic bone disease, variability in the choice and the frequency of administration of these agents. Opinions were sought on potential outcomes for future trials.

Results

A total of 193 clinicians were contacted and 90 completed our survey (response rate 49% after adjustment for inactivity). Survey respondents were medical oncologists (71.1%), radiation oncologists (21.1%) and urologists (7.8%). The findings suggest that once bone-targeted agents are started they are rarely discontinued. More agents are used in breast cancer than in prostate cancer. There was considerable interest in performing studies of de-escalated therapy in both breast and prostate cancer. Physicians requested (86%) that the primary study endpoint be the occurrence of skeletal related events and not biomarker driven.

Conclusions

Despite clinical practice guidelines and widespread use, significant areas of clinical equipoise with respect to use of bone-targeted agents exist. Findings from this survey suggest that physicians are interested in de-escalated therapy for both breast and prostate patients. However, the use of multiple agents in breast cancer and the desire for skeletal related events to be the primary endpoint means that very large randomized studies will be required.

Hyperparathyroid crisis: use of bisphosphonates as a bridge to parathyroidectomy

BACKGROUND

Hyperparathyroid crisis is an uncommon, potentially lethal condition for which emergent parathyroidectomy has been advocated.

STUDY DESIGN

The manifestations of hyperparathyroid crisis and outcomes of bisphosphonate-based therapy and delayed parathyroidectomy were determined and compared with cases from a review of the literature. Laboratory indices and gland weights were compared with those from patients with primary hyperparathyroidism without crisis.

RESULTS

Of the 292 patients operated on for hyperparathyroidism, 8 (2.8%) had hyperparathyroid crisis, consistent with rates of 1.6% to 6% reported in the literature. Hyperparathyroid crisis was manifested by vomiting, nausea, or both (n=6); abdominal pain (n=3); mental status changes (n=3); pancreatitis (n=2); bone pain, osteolytic lesions, or both (n=2); electrocardiogram changes (n=1); and an acute conversion disorder (n=1). Isotonic sodium chloride and furosemide, in combination with a bisphosphonate drug in 7 of 8 patients, resulted in a calcium decline from 16.2+/-1.6 mg/dL to 11.8+/-1.6 mg/dL, with resolution of electrocardiogram and mental status changes, and pancreatitis before resection of an adenoma (n=7) or carcinoma (n=1). Patients with hyperparathyroid crisis had higher parathyroid hormone levels (691.7 +/-662.4 pg/mL versus 172.6 +/-147.5 pg/mL; p=0.062), larger tumor weights (7.5 +/-8.4 g versus 1.6 +/-2.1 g; p=0.085), and lower postoperative calcium levels (7.3 +/-1.6 mg/dL versus 8.7+/-0.9 mg/dL; p=0.035) than patients without crisis. Four (50%) of the 8 tumors were found in ectopic locations. There was no mortality from hyperparathyroid crisis, compared with a 7% mortality rate for cases reported in the literature since 1978.

CONCLUSIONS

Rehydration, calciuresis, and bisphosphonate therapy are effective in correcting life-threatening manifestations of hyperparathyroid crisis, providing an effective bridge to parathyroidectomy.

Osseointegration of cementless implants with different bisphosphonate regimens

Some evidence suggests a daily dose of bisphosphonates improves fixation of cementless metal implants by enhancing osseointegration. Because the necessity of daily administration may result in suboptimal adherence to therapy, single- dose administration is desirable. We examined whether a dose-equivalent single injection of the nitrogen-containing bisphosphonate ibandronate is as effective as a daily injection in improving the osseointegrated surface and enhancing periprosthetic bone mineralization (bone volume to tissue volume) of cementless metal implants. Uncoated titanium and hydroxyapatite-coated titanium implants were surgically inserted into the femoral medullary canal of 55 female Sprague Dawley rats. The animals were randomly assigned subcutaneous treatments with 25 microg/kg body weight ibandronate per day, a dose-equivalent single injection of 28 x 25 microg/kg body weight, or saline solution for control. Histomorphometric evaluation revealed an enhanced osseointegrated surface for hydroxyapatite-coated implants in both treatment groups, but only for daily injections for uncoated titanium implants. Bone volume to tissue volume was improved in both treatment groups. Our results suggest that an equivalent-dose single injection of ibandronate is as effective as a daily dose in improving osseointegration and stabilization of hydroxyapatite-coated titanium implants in this rat model.

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.

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, 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.

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.

Is there a dose response relationship for clodronate in the treatment of tumour induced hypercalcaemia?

Eighty-six patients with tumour induced hypercalcaemia were randomised to 600, 900, 1200 or 1500 mg of intravenous clodronate, according to post hydration serum calcium levels. Sixty-seven were evaluable for response. The overall response rate was 49.3% (95% CI: 36.8-61.8) with no significant difference in response rates, i.e. achievement of normocalcaemia at days 6-9 (corrected serum calcium < or =2.6 mmol l(-1)) across all groups.

The role of bisphosphonates in breast cancer management: review article

Bone metastases are a common problem in the management of breast cancer and are associated with considerable morbidity. Bone pain, hypercalcaemia, fractures and cord compression all occur requiring interventions such as analgesia, radiotherapy and surgery. Bisphosphonates are drugs that are active in the bone microenvironment. Their effects on osteoclasts are well described: they potently inhibit osteoclast mediated bone resorption by delaying the maturation of immature osteoclasts and by directly inducing osteoclast apoptosis. It has been known for some time that bisphosphonates, in combination with intravenous rehydration, effectively treat hypercalcaemia associated with solid malignancies. It has now been demonstrated In clinical trials in breast cancer patients that regular bisphosphonate administration reduces the morbidity associated with osteolytic skeletal metastases. There is an emerging suggestion from clinical trial work that bisphosphonates may be able to reduce or delay the development of skeletal metastases although this remains controversial as the three published trials present conflicting results. The more potent third-generation bisphosphonates, such as zoledronate, are now being tested for each of these indications with promising results and may replace other bisphosphonates in the future. Laboratory studies have recently demonstrated that bisphosphonates have direct cytotoxic effects against breast cancer cells in vitro, inducing apoptosis and preventing adhesion to bone. This adds support to the hypothesis that bisphosphonates may have a genuine beneficial effect in the adjuvant setting.

[Tumor-induced hypercalcemia. Review of bisphosphonate treatment]

INTRODUCTION

The incidence of tumor-induced hypercalcemia is between 10 to 20%. New treatments justify this review article.

CURRENT KNOWLEDGE AND KEY POINTS

Tumor-induced hypercalcemia (half of all hypercalcemia) is divided into two groups: hematological tumors (10%), and solid tumors (90%), with osteolytic hypercalcemia and humoral hypercalcemia of malignancy (HHM: mediators include PTHrP). The two most common causes of tumor-induced hypercalcemia are lung cancer and breast cancer. Tumor-induced hypercalcemia most commonly disturbs gastrointestinal, neurological, renal and cardiovascular functions. These symptoms may be erroneously attributed to the underlying malignancy or its therapy. Prognosis of tumor-induced hypercalcemia is very poor, with median survival being about 3 months. Bisphosphonates have emerged as the standard treatment of tumor-induced hypercalcemia. The intravenous administration of isotonic saline is the first step in the management of tumor-induced hypercalcemia. Specific treatment of cancer remains essential to prevent TIH relapse.

FUTURE PROSPECTS AND PROJECTS

New bisphosphonates have appeared, the most potent known bisphosphonate today is zoledronate.

Gastrointestinal problems in patients with advanced gynaecological malignancy

Gastrointestinal problems are among the most common problems encountered in the management of women with far advanced gynaecological malignancy. They frequently have a multifactorial aetiology and may require a number of different strategies for effective management. Recognition of the central role of alimentary function in human life is essential to effective treatment. Elucidation of the probable cause of each problem is essential. A thorough knowledge of the natural history of the disease and the patient's current status and future prospects is needed to ensure the highest standard of care for the individual suffering from the problem.

Prolonged, symptomatic hypocalcemia with pamidronate administration and subclinical hypoparathyroidism

A 62-yr-old woman with thyroid carcinoma metastatic to bone, and a history of subclinical hypoparathyroidism was admitted to the hospital in hypocalcemic crisis 5 wk after receiving iv pamidronate. The patient had tetany and laryngospasm. An electrocardiogram showed junctional rhythm with QT segment prolongation. The patient had previously maintained a low-normal serum calcium on 500-750 mg of calcium carbonate and 600 IU of vitamin D daily. One week after pamidronate administration the patient's calcium and vitamin D supplementation were inadvertently discontinued. She continued to take daily intranasal calcitonin. At the time of her hospitalization for hypocalcemia, the patient's serum calcium was 4.3 mg/dL. The patient received aggressive calcium and vitamin D supplementation. However, her serum calcium remained below 6 mg/dL for a 2-wk period, and took another week to return to the normal range. In this article, we discuss the counterregulatory responses necessary to maintain calcium homeostasis following osteoclast inhibition by bisphosphonates. We also review the risk factors for hypocalcemia following bisphosphonate administration. Pamidronate and other bisphosphonates are becoming an integral part of the management of normocalcemic patients with malignant bone disease. Therefore, awareness of risk factors for hypocalcemia and familiarity with avenues available for protection from potentially catastrophic hypocalcemia are both crucial.

A Phase I, open label, dose ranging trial of intravenous bolus zoledronic acid, a novel bisphosphonate, in cancer patients with metastatic bone disease

BACKGROUND

Bone metastases typically are associated with osteolytic bone destruction, resulting in bone pain, pathologic fractures, spinal cord compression, and hypercalcemia. Bisphosphonates are potent inhibitors of normal and pathologic bone resorption and represent a significant therapeutic improvement in the management of patients with lytic bone metastases. Zoledronic acid is a new-generation, highly potent, nitrogen-containing bisphosphonate that to the authors knowledge is the most potent inhibitor of bone resorption currently in clinical trials. The objectives of the current study were to assess the safety and tolerability of increasing doses of zoledronic acid and to determine its activity with respect to reducing biochemical markers of bone resorption in cancer patients with bone metastases.

METHODS

Forty-four cancer patients with bone metastases or primary bone lesions were enrolled sequentially into 1 of 5 fixed ascending-dose treatment groups. Each patient received a single intravenous bolus injection of 1, 2, 4, 8, or 16 mg of zoledronic acid over 30-60 seconds. Patients were monitored for 8 weeks for the evaluation of clinical findings, adverse events, vital signs, electrocardiograms, markers of bone resorption, and urinary N-acetyl-beta-D-glucosaminidase.

RESULTS

Zoledronic acid was safe and well tolerated at all dose levels tested. Commonly reported adverse events included bone pain, fever, anorexia, constipation, and nausea, which were experienced by a similar proportion of patients in each treatment group. Seven patients reported serious adverse events, none of which appeared to be related to the study drug. Zoledronic acid effectively suppressed biochemical markers of bone resorption, including the highly specific markers N-telopeptide and deoxypyridinoline, for up to 8 weeks in the 2-16-mg dose groups and for a shorter duration in the 1-mg group.

CONCLUSIONS

In the current study, zoledronic acid was safe and well tolerated and demonstrated potent inhibition of bone resorption. The authors believe it may improve the treatment of metastatic bone disease.

Current drug therapy for multiple myeloma

Recent years have witnessed tremendous advances in the molecular pathogenesis and management of multiple myeloma. Standard chemotherapy (melphalan and prednisone; MP) has been the mainstay of treatment of multiple myeloma for about 3 decades. However, it is no longer considered the 'gold standard', particularly for those patients who will subsequently undergo intensive chemotherapy with autologous or allogeneic peripheral blood stem cell (PBSC) or bone marrow transplantation (BMT), or for patients with refractory myeloma. A variety of induction combination chemotherapy regimens have been developed, some of which have demonstrated an improved response rate and duration and a superior 5-year survival rate when compared with standard chemotherapy. The early use of high dose chemotherapy with autologous PBSC support or BMT has significantly increased the complete remission rate, and has prolonged event-free sur vival and overall survival. Allogeneic bone marrow or PBSC transplantation may be a good option for selected patients with poor prognostic features. The role of interferon-alpha in multiple myeloma is still inconclusive despite many years of clinical evaluation. The clinical application of chemosensitising agents that can inhibit P-glycoprotein (P-gp) expression and function, and particularly the development of more potent P-gp modulators such as valspodar (PSC 833) and elacridar (GF120918) has made it possible to reverse multidrug resistance in some refractory patients and to enhance the efficacy of chemotherapeutic agents. Immunotherapeutic approaches to purging of autologous bone marrow or PBSC, or as adjuvant therapy for minimal residual disease, show great promise. Finally, a number of new therapies specifically designed to treat many of the complications of multiple myeloma are improving clinical outcomes and quality of life for these patients.

Markers of bone resorption in patients treated with pamidronate

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

The role of bisphosphonates for the treatment of bone disease in multiple myeloma

Palliative therapy is often a major objective for clinicians while treating advanced cancer. This is particularly true in multiple myeloma (MM), where bone involvement markedly influences the quality of life of patients. Bisphosphonates (BP) are a new class of drugs regulating bone turnover, which exert their activity mainly by inhibiting osteoclast bone resorption. Three BP (etidronate, ETD; clodronate, CDN; pamidronate, PMD) have so far been investigated in the clinical setting for treating bone disease in patients with MM. The results of these trials, including our own experience, are reviewed here. Although all three BP were effective in lowering hypercalcemia of MM patients, PMD, a second generation BP, clearly had the most substantial long term clinical benefits regarding bony complications, pain and quality of life. CDN also showed some activity in reducing the development of new lytic lesions, while no significant beneficial effect was seen in patients using ETD. Interestingly, some studies have reported an improved survival in subsets of MM patients receiving BP and this is in agreement with recent evidence of possible direct anti-neoplastic activities of these drugs mediated through reduction of IL-6 production and stimulation of neoplastic cell apoptosis.

Use of pamidronate in the management of acute cancer-related hypercalcemia in children

PURPOSE

To determine whether pamidronate is a safe and effective agent for the treatment of severe hypercalcemia of malignancy in children.

MATERIALS AND METHODS

A retrospective review of the charts of five children treated with pamidronate 1-2 mg/kg for severe, refractory hypercalcemia of malignancy. All children failed conventional therapy. Statistical analysis was done utilizing the two-tailed Student's t-test.

RESULTS

All five children had complete resolution of their hypercalcemia in a predictable pattern within 24-48 hours. The average decrease in serum calcium was 1.63 mmol/L (6.54 mg/dl). (P < .01) The adverse effects were mild and transient, and consisted of hypocalcemia, hypophosphatemia, and hypomagnesemia.

CONCLUSIONS

Pamidronate at a dose of 1 mg/kg is a safe and effective treatment for severe, refractory hypercalcemia of malignancy in children.

Effects of YM175, a new-generation bisphosphonate, on hypercalcemia induced by tumor-derived bone resorbing factors in rats

YM175 (disodium cycloheptylaminomethylenediphosphonate monohydrate) is a new-generation bisphosphonate with stronger inhibitory activity on bone resorption than first-generation bisphosphonates. In the present study, the effect of YM175 on hypercalcemia induced in rats by single administration of either parathyroid hormone-related protein (PTHrP) or concomitant administration of PTHrP and interleukin 1beta (IL-1beta) was investigated. YM175 (0.01-1 mg/kg, i.v.) inhibited the increase in serum free calcium concentration induced by continuous administration of PTHrP alone (3 microg/rat/day, s.c., 7 days) dose-dependently. The inhibitory effect of YM175 appeared the day after administration and remained 3 days after administration. The effect of YM175 reached a maximum 2 days after administration, at which time the ED50 value of YM175 was calculated to be 0.041 mg/kg, i.v., revealing a potency approximately 50- and 10-fold stronger than those of either pamidronate or alendronate, respectively. In contrast, elcatonin (1-10 units/kg, s.c.) only transiently inhibited PTHrP-induced free calcium increase. YM175 (0.1-3 mg/kg, i.v.) also inhibited the increase in the serum free calcium concentration induced by continuous concomitant administration of both PTHrP and IL-1beta in a dose-dependent manner. These results indicated that YM175 is expected to be a useful drug for hypercalcemia associated with malignant tumors due to its efficacy and range of effect.

Utility of bisphosphonates in treating bone metastases

Bone is the most common site of metastases from breast and prostate cancer, and bone destruction is characteristic of multiple myeloma. Increased osteoclast activity plays a key role in cancer-induced bone destruction. Bisphosphonates reduce osteoclastic bone resorption through various mechanisms as yet not fully elucidated. Bisphosphonates have proven to be effective in the treatment of tumor-induced hypercalcaemia. Several clinical trials indicated that these compounds can positively influence many aspects of neoplastic bone disease, however, many questions regarding their long-term efficacy and optimal therapeutic schedule await clarification from well-designed clinical trials.

A randomised double-blind comparison of intravenous pamidronate and clodronate in the hypercalcaemia of malignancy

In conjunction with rehydration, the bisphosphonates are the treatment of choice for hypercalcaemia of malignancy. Single infusions of either pamidronate or clodronate are usually effective, but a direct comparison of the two agents given at the highest doses commonly used has not been performed. Forty-one patients (15 breast, 12 squamous carcinomas, four lymphomas, four bladder, two prostate and four others) with hypercalcaemia of malignancy (corrected serum calcium > 2.7 mmol l-1) persisting after 48 h of saline rehydration were randomly allocated to receive a 4 h intravenous (i.v.) infusion of either pamidronate 90 mg or clodronate 1500 mg. No other systemic anti-cancer treatment was prescribed. There were no significant differences in the post-hydration serum calcium values (mean 3.17 mmol l-1 for pamidronate and 3.06 mmol l-1 for clodronate), tumour type or frequency of bone metastases between the two treatments. One patient on each treatment died within 2 days and was not assessable for response. A total of 19/19 (100%) patients achieved normocalcaemia following pamidronate and 16/20 (80%) with clodronate. The median time to achieve normocalcaemia was 4 days (range 2-14) for pamidronate and 3 days (range 2-6) with clodronate. The median duration of normocalcaemia was 28 days (range 10-28+ days) after pamidronate and 14 days after clodronate (range 7-21 days) (P < 0.01). Two patients who failed to respond to clodronate were successfully treated with pamidronate and achieved normocalcaemia for 14 and > 28 days respectively. Two patients experienced fever after pamidronate but no significant toxicity was observed with either treatment. We conclude that both agents are effective in the management of hypercalcaemia of malignancy. At the doses studied, the effects of pamidronate are more complete and longer lasting than those of clodronate.

Pamidronate infusions as single-agent therapy for bone metastases: a phase II trial in patients with breast cancer

Pamidronate is a potent biphosphonate which modulates tumour-induced osteolysis (TIO) by inhibiting osteoclast-mediated bone resorption. In a phase II trial, 69 breast cancer patients with symptomatic progressive bone metastases were given infusions of pamidronate 60 mg over 1 or 4 h every 2 weeks for a maximum of 13 infusions or until progressive disease (PD) at any site. No other systemic anticancer therapy was allowed. Pain was measured using a visual analogue scale, mobility using a detailed eight-point questionnaire and analgesic intake using a six-point scale. Improvements in pain, mobility and analgesic scores occurred in 61, 50 and 30% of patients, respectively, with 33, 21 and 16% achieving a 40% improvement for > or = 8 weeks. At trial discontinuation, baseline levels of pain and mobility had improved by 27% (P = 0.001) and 20% (P = 0.004), respectively, despite a one category reduction in analgesic intake in 27% of patients. Using this relatively high dose of pamidronate, symptomatic response was independent of the number of bone metastases and also of infusion rate. The infusions were well tolerated with no major toxicities reported. Pamidronate infusions provide useful palliation for breast cancer patients with symptomatic bone metastases.

Pain relief and quality-of-life assessment following intravenous and oral clodronate in hormone-escaped metastatic prostate cancer

OBJECTIVE

To establish the efficacy of intravenous clodronate followed by maintenance oral clodronate in patients with painful bone metastases resulting from hormone-resistant prostate cancer.

PATIENTS AND METHODS

A multicentre open study of 27 patients assessed the efficacy of clodronate treatment by estimating the reduction in World Health Organization (WHO) Pain Score, the increase in WHO Performance Status and by a novel quality-of-life/activity score.

RESULTS

Ten of 27 patients achieved significant pain relief after receiving 300 mg/day of intravenous clodronate for 10 days. This was matched by an improvement in the activity score and WHO Performance Status. Three of 27 patients continued to have relief from pain after 3 months of oral clodronate therapy.

CONCLUSION

Intravenous clodronate therapy was effective in relieving the pain resulting from prostate cancer bone metastases in 10 of 27 patients but the benefit was shortlived. The use of a personal quality-of-life/activity questionnaire which assesses aspects of everyday life that are important to the patient may be more appropriate for patients with very advanced prostate cancer than are other quality-of-life questionnaires in current use.

Effects of the antihypercalcemic drugs gallium nitrate and pamidronate on hormone release of pathologic human parathyroid cells

BACKGROUND

Gallium nitrate and the bisphosphonates pamidronate and its dimethylated derivative comprise antihypercalcemic drugs with actions on bone. This study examines the in vitro effects of these compounds on human parathyroid cells.

METHODS

Parathyroid hormone (PTH) release and the concentration of cytoplasmic calcium ion (Ca2+) of dispersed cells from parathyroid glands of 27 patients with sporadic primary or uremic hyperparathyroidism was measured.

RESULTS

In 1.25 mmol/L external Ca2+, 200 mumol/L gallium nitrate inhibited PTH release from preparations of primary and uremic hyperparathyroidism by 14% and 22%, respectively. Similar reductions were evident also in 0.5 and 3.0 mmol/L Ca2+. The gallium nitrate-induced suppression of PTH release was dose dependent in the 2 to 200 mumol/L range. Cytoplasmic Ca2+ concentration displayed a biphasic rise on elevation of external Ca2+ and remained unaffected by gallium nitrate. None of the bisphosphonates altered PTH release of pathologic human or normal bovine parathyroid cells.

CONCLUSIONS

The results support clinical usefulness of gallium nitrate through its dual actions on bone and the parathyroid. The findings substantiate that gallium may reduce PTH release by stabilization of the plasma membrane rather than by interference with the surface cation receptor mediating Ca2+ regulation of the secretion.

Optimal frequency of administration of pamidronate in patients with hypercalcaemia of malignancy

OBJECTIVE

Hypercalcaemia of malignancy (HM) is a common metabolic complication associated with cancer. The hypocalcaemic effects of medications used to reduce serum calcium levels in HM are short lived and relapse in hypercalcaemia is not uncommon. Pamidronate is one of the most commonly used bisphosphonates in the treatment of HM but there are no specific guidelines for the frequency of use of this drug in recurrent hypercalcaemia. This study was conducted to assess the optimum frequency of pamidronate therapy necessary to maintain normocalcaemia in patients with HM.

DESIGN AND PATIENTS

Thirty-four patients with HM were randomly allocated into two groups and treated with intravenous pamidronate administered every 14th or 21st day for 16 weeks (n = 17 each group). Serum calcium and urinary hydroxyproline creatinine ratio were measured at weekly intervals.

RESULTS

The calcium-lowering effect of pamidronate was apparent by 48 hours and normocalcaemia was maintained for an average of 15 days. When the drug was administered every 3 weeks, hypercalcaemia and associated symptoms developed in 50% of patients (22 separate episodes) during the 3rd week, before the next dose of pamidronate. The incidence of symptomatic hypercalcaemia was significantly decreased (10%, 8 separate episodes, P < 0.01) and survival was improved (P < 0.05) in patients who received pamidronate every 2nd week, thereby minimizing the unpleasant and potentially dangerous effects of hypercalcaemia.

CONCLUSIONS

Intravenous pamidronate 60 mg/dose, administered every two weeks, can maintain normocalcaemia in the vast majority of patients with hypercalcaemia of malignancy.

Treatment of tumour-induced hypercalcaemia with the bisphosphonate pamidronate: dose-response relationship and influence of tumour type

BACKGROUND

Patients with humoral hypercalcaemia of malignancy appear to respond less well to biphosphonate therapy than hypercalcaemic patients with osteolytic metastases. On the other hand, pamidronate is currently the most potent of the commercially available biphosphonates and it is recommended that its dose be increased as a function of pretreatment calcium levels.

PATIENTS AND METHODS

We reviewed our experience with pamidronate in 160 patients with tumour-induced hypercalcemia (TIH) persisting after rehydration, particularly the influence of the dose administered, the tumour type and the presence of bone metastatic involvement on the calcaemic and calciuric response to pamidronate therapy.

RESULTS

Serum Ca was normalized in 92% of the cases (87% when Ca was corrected for protein levels). After therapy, 59% of the patients developed asymptomatic hypocalcaemia (30% for Corr. Ca levels). A multiparameter regression analysis revealed that the response to pamidronate was significantly (P < 0.01) influenced by initial Ca levels up to days 5-7 and, thereafter, only by the dose received. To confirm the dose effect, we divided the patients into three groups according to the median dose received, namely 0.5 mg/kg (n = 35), 1.0 mg/kg (n = 52), and 1.5 mg/kg (n = 73). The differences among the three groups became significant (P < 0.05) from days 5-7 until the end of the evaluation (days 22-26). Similarly, the success rate, considering Corr. Ca levels, was 80% for the 0.5 and 1.0 mg/kg groups combined, compared to 94% for the 1.5 mg/kg group (P < 0.05). The duration of normocalcaemia was similarly more prolonged in the high-dose group. There was a dose-response relationship only in patients with Ca levels above 3.0 mmol/L and in patients with an elevated index of tubular calcium reabsorption. By contrast, the decrease in Ca levels and in fasting urinary calcium excretion, a sensitive index of bone resorption, were not significantly influenced by the primary tumour site or by the presence of bone metastatic involvement.

CONCLUSIONS

Our data demonstrate a dose-response relationship for pamidronate in TIH over an efficient hypocalcaemic dose range, at least in patients with an elevated tubular calcium reabsorption, which helps to resolve conflicting data in the literature. We suggest that a dose of around 1.5 mg of pamidronate/kg is optimal for the treatment of TIH, except in patients with mild hypercalcaemia, for whom a dose of 1 mg/kg appears to be sufficient. At these dose levels, the efficacy of pamidronate is not significantly influenced by the tumour type or the degree of metastatic bone involvement.

Histomorphometrical analysis of the effects of the bisphosphonate alendronate on bone loss caused by experimental periodontitis in monkeys

This study tested the efficacy of alendronate, a bisphosphate, in reducing alveolar bone loss caused by experimental periodontitis in cynomolgus monkeys. Periodontitis was initiated in adult monkeys by ligating mandibular molar teeth at the cementoenamel junction (CEJ) and subsequently inoculating the ligature with Porphyromonas (Bacteroides) gingivalis. Contralateral, homologous non-ligated teeth served as controls. Animals received, intravenously, either saline (placebo) or alendronate at 0.05 or 0.25 mg/kg every 2 weeks for 16 weeks. After the animals were sacrificed, coronal sections through mandibular molars were subjected to histomorphometrical analysis. No overt side-effects were observed in any of the animals participating in this study. In placebo-treated animals, ligation and inoculation resulted in significant bone loss both at the CEJ and at the furcation. Alendronate at 0.05 mg/kg significantly reduced bone loss associated with the experimental periodontitis at both sites. In contrast, the dose of 0.25 mg/kg was ineffective in attenuating alveolar bone loss in the furcation area and only slightly effective in preventing it at the CEJ area. The results of the histomorphometric analysis correlate closely with those of the radiographic analysis of the same experiment. These data indicate that alendronate could reduce the loss of alveolar support associated with periodontitis and suggest that bisphosphonates, by virtue of their significant inhibitory action on osteoclasts, may become a treatment modality in the battle against alveolar bone destruction during periodontal disease.

Disodium Pamidronate in the Treatment of Bone Metastases from Breast Cancer

Aims and Background

Symptomatic relief of bone metastases with biphosphonates has been previously reported, but limited data are available on the possibility of the induction of sclerosis in osteolytic lesions.

Methods

We therefore initiated an open study with disodium pamidronate (45 mg infused over 1 h and repeated every 21 days) in patients with bone metastases from breast cancer pretreated with chemotherapy and/or hormonetherapy. Fourteen patients wiht measurable lytic or mixed bone disease entereted the study. No other systemic therapy for breast cancer was allowed after their Inclusion in the study.

Results

No radiologic evidence of bone sclerosis of lytic disease was seen. After 2 months of therapy, 9 patients had progressed and 5 had stable disease. The median time to progression of bone disease was 1.6 months (range, 1-9). No significant improvement in terms of symptomatic status or analgesic consumption was recorded. The treatment was well tolerated, and no significant local or systemic toxicity was observed.

Conclusions

Disodium pamidronate at a dose of 45 mg every 3 weeks is not capable of inducing sclerosis of lytic lesions from pretreated breast cancer. Further trials concentrating on higher dosages of disodium pamidronate are warranted.

Methylpentylaminopropylidenebisphosphonate (BM 21.0955): a new potent and safe bisphosphonate for the treatment of cancer-associated hypercalcemia

Bisphosphonates have been shown to be effective in lowering serum calcium levels in patients with cancer-associated hypercalcemia. 1-Hydroxy-3-(methylpentylamino)propylidenebisphosphonate (BM 21.0955) was developed as a third generation bisphosphonate and has been recently proven effective in animals and in patients with Paget's disease or tumor osteolysis. Thirty-six patients with cancer-associated hypercalcemia were treated with increasing doses (0.2-2.0 mg) of BM 21.0955 by single i.v. infusion over 4 h in a phase I trial. Six patients were rejected from analysis due to concomitant treatment with other bisphosphonates or chemotherapy. After rehydration and infusion of BM 21.0955 the mean serum calcium levels fell significantly (P < 0.001), from 3.29 +/- 0.49 mmol/l to 3.04 +/- 0.44 mmol/l until day 2 and normalized on day 6 (2.66 +/- 0.33 mmol/l). Serum calcium was reduced in all patients and normalized in 16. No symptomatic hypocalcemia occurred. Mean serum creatinine decreased significantly (P < 0.01), from 1.25 +/- 0.58 mg/dl (day 0) to 1.05 +/- 0.37 mg/dl (day 6). The mean urinary calcium/creatinine concentration fell significantly (P < 0.001), from 1.90 +/- 1.16 mM/mM (day 0) to 0.37 +/- 0.34 mM/mM/l (day 6). There were no subjective drug-related side effects during or after the infusion. Thirteen patients had elevations of morning body temperature above 38 degrees C. This was due to confirmed infections in five patients and possibly drug- or tumor-related in the other eight. We conclude from these preliminary results that a single infusion of BM 21.0955 is an effective and safe way to treat cancer-associated hypercalcemia.

[Bone metastases of colorectal cancers: apropos of 8 cases]

Having found, in the same medical centre, an abnormally high (15%) frequency of bone metastases from colorectal carcinoma, the authors report a series of 8 cases and review what is now known of this reputed rare (4%) metastases. Their clinical and imaging features are not very different from secondary bone lesions of other origins. They usually appear approximately 5 years after the primary tumour has been diagnosed; and they are rarely isolated, being part of a diffuse metastatic disease; their prognosis is in fact conditioned by visceral metastases (liver, lung, peritoneum). Concerning treatment, pain relieving radiotherapy is crucial, as witnesses by the authors. Chemotherapy must always be prescribed for its proven effectiveness against visceral lesions. The other medicinal treatments (e.g. analgesics, bisphosphonates) are very useful. Surgery must be reserved to emergency situations (spinal cord compression) and to patients in good general condition. To our 8 patients these treatments brought comfort and increased survival. Survivals of at least 6 to 9 months were obtained, and one patient is still alive 14 months after the diagnosis of bone metastasis. These results compare favourably with the 4 months median survival observed in other series.

Parathyroid carcinoma presenting with a brown tumour of the mandible in a young man

A 27-year-old man presented to his dentist with a swelling in his lower jaw. Histology revealed this to be a brown tumour associated with primary hyperparathyroidism and severe but asymptomatic hypercalcaemia. A large parathyroid adenoma was removed and the serum calcium fell to normal. Hypercalcaemia recurred and re-exploration of the neck revealed parathyroid metastases in cervical lymph nodes. A modified radical neck dissection was performed and he has remained normocalcaemic on Vitamin D analogues for 2 years. Bone disease of the mandible is a very rare presentation of primary hyperparathyroidism. The diagnosis of parathyroid malignancy is often difficult histologically, and the optimum treatment is uncertain.

Long-term follow up of breast cancer patients treated for hypercalcaemia with aminohydroxypropylidene bisphosphate (APD)

No systematic data are available about the long-term follow up of breast cancer patients treated with amino-hydroxypropylidene bisphosphate (APD) for hypercalcaemia and about the results of APD treatment of recurrent hypercalcaemia in these patients. Treatment with intravenous APD (10-15 mg daily until normalization of the serum calcium level) normalized serum calcium in 29 of 31 patients with hypercalcaemia due to advanced breast cancer. Survival in these 29 patients varied between 8 and 693 days (median 140 days) and 7 patients achieved a partial remission or stabilisation of disease during subsequent anti-tumor therapy. In 16 of the 29 patients in whom APD treatment was initially successful, hypercalcaemia recurred after a median period of 65 days. Eleven of these patients received a second course of APD, which was equally successful as the first in terms of percentage of patients with normalization of serum calcium, total dose of APD needed, and duration to normalization of serum calcium. Recurrent hypercalcaemia occurred significantly faster after the second successful APD course (median 17 days) than after the first (median 65 days). When only patients with progressive disease were taken into account, recurrence of hypercalcaemia usually occurred early, both after a first (median 23 days) and after a second successful APD course (median 17 days). Normalization of serum calcium occurred in 4 of 6 patients receiving a third APD course, in all 3 patients receiving a fourth, and in 1 of 2 patients receiving a fifth course.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors predicting the acute effect of pamidronate on serum calcium in hypercalcemia of malignancy

In this study we retrospectively reviewed results of the first 9 days of treatment with pamidronate at doses of 30 mg (n = 13), 45 mg (n = 9), and 90 mg (n = 13) in an attempt to see what factors influenced the response of serum calcium to pamidronate. The nadir of serum calcium obtained post treatment was correlated with pretreatment levels of nephrogenous cyclic adenosine monophosphate (NcAMP), the renal tubular threshold for phosphate reabsorption (TmPO4), and the renal tubular threshold for calcium reabsorption (TmCa). Using the post treatment serum calcium levels, patients were divided into "good" and "poor" responders depending on whether a normal serum calcium was obtained. Pretreatment NcAMP was significantly correlated with the magnitude of the response of serum calcium (r = 0.45, P = 0.0001). Pretreatment NcAMP was significantly higher in the poor responders (mean +/- SEM): 65.0 +/- 9.4 nmol/liter GF (poor responders) versus 29.6 +/- 6.3 (good responders), P = 0.004. NcAMP as a predictor of the acute response of serum calcium showed a sensitivity of 93% and a specificity of 72%. Pretreatment TmPO4 was negatively correlated with the serum calcium response post treatment (r = -0.41, P = 0.003). However, though TmPO4 tended to be lower in the poor responders, this was not statistically significant [0.65 mmol/liter GF +/- 0.09 (poor responders) versus 0.76 mmol/liter GF +/- 0.06 (good responders)]. As a predictor of the acute response of serum calcium, TmPO4 was less good with a sensitivity of 70% and specificity of 58%. No significant correlation was present between TmCa and the serum calcium response.(ABSTRACT TRUNCATED AT 250 WORDS)

Pamidronate

OBJECTIVE

The primary objective of this article is to introduce readers to the use of a new agent, pamidronate. The article discusses its use in hypercalcemia of malignancy (HCM), osteolytic lesions, and Paget's disease. Pharmacokinetic data and clinical trials are reviewed, as well as adverse effects and dosage guidelines.

DATA SOURCES

A MEDLINE search was used to identify English-language studies involving pamidronate for the period from 1970 to 1992.

STUDY SELECTION

As comparative trials were few in number, trials using pamidronate as a single agent were also reviewed.

DATA EXTRACTION

Sparse pharmacokinetic data were obtained from clinical trials. All clinical trials available at the time of publication that met the following criteria were reviewed: (1) allowed for adequate rehydration prior to drug therapy; (2) reported standardized and corrected serum calcium concentrations; (3) separated data obtained from patients who received pamidronate alone from those who received pamidronate and concurrent chemotherapy.

RESULTS

Pamidronate has a pharmacologic profile similar to that of etidronate, but pamidronate is more potent and has a longer duration of effect. It has been investigated primarily in the treatment of HCM as well as in the treatment of osteolytic bone metastases and Paget's disease. In hypercalcemia of malignancy it appears to be as effective as established agents with the advantage that a single dose of pamidronate 90 mg iv provides a durable response. In Paget's disease chronic oral administration has also been shown to be effective in relieving bone pain. Adverse reactions with intravenous administration are transient and self-limiting and usually occur with the first dose. The most common adverse effect is a transient and self-limiting fever. Chronic oral administration of doses greater than 600 mg/d is associated with gastrointestinal toxicities.

CONCLUSIONS

Although more well-designed clinical trials comparing pamidronate with standard therapies and other available agents are necessary, initial results indicate that pamidronate is an effective and promising alternative for use in the treatment of HCM.

Plicamycin and pamidronate in symptomatic tumor-related hypercalcemia: a prospective randomized crossover trial

We have conducted a randomized crossover comparative trial of a single-dose course of disodium (3-amino-1-hydroxypropylidene) bisphosphonate pentahydrate (pamidronate) and plicamycin in 48 patients with a first occurrence of tumor-related hypercalcemia. All patients had hypercalcaemia-associated symptoms and serum-calcium levels (corrected for total protein) greater than or equal to 2.80 mmol/l. Pamidronate and plicamycin were given concurrently with rehydration immediately after diagnosis of hypercalcaemia was made. Both agents lowered serum calcium levels significantly within 1 week, with 88% of the evaluable patients in the pamidronate group and 45% of those in the plicamycin group achieving normocalcemia (p less than 0.01). In the patients who received pamidronate, the duration of normocalcemia was longer (p less than 0.05) and there was a significant decrease in serum creatinine (p less than 0.05). Vomiting occurred in 8 of 22 evaluable patients (36%) who received plicamycin, but in none of 25 evaluable patients who received pamidronate (P less than 0.01). Phlebitis occurred at the infusion site in more of the pamidronate-treated patients (P less than 0.05). Hypocalcemia, which occurred in 8 of 25 evaluable patients (32%) in the pamidronate group and in 1 of 22 of those (5%) in the plicamycin group, was either clinically asymptomatic or mild, except in one pamidronate-treated patient. Overall, pamidronate was found to be more effective and better tolerated than plicamycin, thereby confirming results of previous studies that showed pamidronate to be an effective, simple, and safe agent for the relief of the morbidity associated with tumor-related hypercalcemia.

Infusion rate and pharmacokinetics of intravenous pamidronate in the treatment of tumour-induced hypercalcaemia

We report the results of two consecutive randomized studies in the treatment of malignant hypercalcaemia with intravenous pamidronate. Overall normocalcaemia was achieved in greater than 90% of patients and a single infusion of 60 mg pamidronate given over 2 hours was as effective in restoring normocalcaemia as infusions given over 4, 8 or 24 hours. Similarly duration of normocalcemia after treatment with pamidronate and the control of the symptoms of hypercalcaemia were independent of infusion rate. Study of the pharmacokinetics of pamidronate in the treatment of hypercalcaemia show this drug to have a very high clearance due to calcified tissue retention and renal excretion. The initial half life of the drug in plasma is very short and most of the drug is cleared before distribution equilibrium is achieved. Short infusions of pamidronate are as safe and effective as infusions given over a longer time and are therefore to be preferred because of their greater convenience.

[Osteolytic metastases of breast cancer and biphosphonates]

Three-quarters of breast carcinomas at an advanced stage display metastases, usually of the osteolytic type. Osteolysis results from a predominant increase of osteoclastic activity stimulated by humoral or local factors secreted by cancerous cells. Bisphosphonates interfere with osteoclasts and therefore can reduce the osteolysis. These compounds act through three main mechanisms: physico-chemical inhibition of bone crystal, cytostatic effect on osteoclasts, and in the case of pamidronate, direct or indirect action on the mononucleate precursors of osteoclasts. Three bisphosphonates are now available: etidronate, clodronate and pamidronate. Ten published studies report on their use in breast carcinoma with osteolytic metastases, and without hypercalceamia. Four studies concern clodronate in 54 patients, and six studies concern pamidronate in 128 patients. Intravenous pamidronate seems to be the more effective of the two, with densification of the lytic areas in 25% of the cases. All studies mention a decrease of pain, risk of fracture, hypercalcaemia and new metastatic locations. Side-effects are minimal. Controlled studies are needed to confirm the position of bisphosphonates in the management of malignant osteolysis.

Effect of a single infusion of alendronate in malignant hypercalcaemia: dose dependency and comparison with clodronate

Among aminohydroxybisphosphonate derivatives, alendronate (3-amino-1-hydroxybutylidene-1,1-bisphosphonate) has proved efficacious in diseases with increased bone resorption. However, the effective dose in the treatment of malignant hypercalcemia is not clearly established. In 2 randomized studies, we investigated the effects of alendronate and of clodronate (dichloromethylene bisphosphonate) given as a single infusion in 82 rehydrated patients with malignant hypercalcaemia. Various doses of alendronate or clodronate soon produced a significant fall in plasma calcium (Ca), accompanied by a dose-dependent decrease in the fasting urinary Ca/creatinine ratio, taken as a reflection of bone resorption. During the next 5 days, plasma Ca and fasting urinary Ca/creatinine ratio were lower in the group treated with alendronate than in the clodronate group. The renal handling of Ca was similar in both groups. Because of relapsing hypercalcaemia, some patients received an infusion of alendronate approximately 2 weeks after the first infusion; this normalized the urinary Ca/creatinine ratio in 44% of the cases at day 3. At that time, the plasma Ca was below 2.70 mmol/l in 33%. Our results indicate that alendronate decreased bone resorption and calcaemia in cancer patients in a dose-dependent manner.

Disodium pamidronate versus mithramycin in the management of tumour-associated hypercalcemia

Twenty-eight consecutive hypercalcemic patients with cancer referred to our department were included in a randomized study, comparing the second generation bisphosphonate pamidronate (APD) with our standard treatment consisting of rehydration, mithramycin (repeatedly) and supportive care. Three patients were excluded, due to rapid deterioration and death, leaving 25 evaluable patients. APD was administered as a single i.v. infusion of 30, 60 or 90 mg depending on the serum calcium, while mithramycin was given in doses of 1.25 mg and repeated if necessary within the first three days. The primary endpoint of the study was the serum calcium day 6. APD normalized serum calcium in all patients, and 12 out of 14 were still normocalcemic day 12. In contrast, mithramycin was effective only in 3 out of 11 patients, and in these patients hypercalcemia recurred rapidly. The success of APD was underscored by the fact that the patients in this group achieved a significantly better performance status after treatment. No serious side-effects were recorded in either group.

Management of disorders of calcium homoeostasis

Severe hypercalcaemia may be life-threatening and requires prompt management. Whatever the cause, the aim of therapy should obviously be to eradicate the source of hypercalcaemic factors. After rehydration, which is an essential first step in the management strategy, and after evaluation of the prevailing pathogenetic mechanism, the acute treatment will be aimed at increasing urinary Ca excretion and inhibiting bone resorption. Among the various pharmacological agents, bisphosphonates appear to be the drugs of first choice, because of their efficacy and their virtual absence of side-effects. The decision to treat hypocalcaemia is determined by the extent of the symptoms and the risk of complications. The treatment of acute hypocalcaemia comprises the parenteral administration of Ca or magnesium, when magnesium deficiency can be suspected. Then, chronic hypocalcaemia may require the use of 1,25-dihydroxyvitamin D, once the replenishments of vitamin D stores have been assured.