Efficacy of clodronate, pamidronate, and zoledronate in reducing morbidity and mortality in cancer patients with bone metastasis: a meta-analysis of randomized clinical trials

Etidronate-based organic salts and ionic liquids: In vitro effects on bone metabolism

Bisphosphonates are a class of drugs widely used for the treatment of several pathologies associated with increased bone resorption. Although displaying low oral bioavailability, these drugs have the ability to accumulate in bone matrix, where the biological effects are exerted. In the present work, four mono- and dianionic Etidronate-based Organic Salts and Ionic Liquids (Eti-OSILs) were developed by combination of this drug with the superbases 1,1,3,3-tetramethylguanidine (TMG) and 1,5-diazabicyclo(4.3.0)non-5-ene (DBN) as cations, aiming to improve not only the physicochemical properties of this seminal bisphosphonate, but also its efficacy in the modulation of cellular behavior, particularly on human osteoclasts and osteoblasts. It was observed that some of the developed compounds, in particular the dianionic ones, presented very high water solubility and diminished or absent polymorphism. Also, several of them appeared to be more cytotoxic against human breast and osteosarcoma cancer cell lines while retaining low toxicity to normal cells. Regarding bone cells, a promotion of an anabolic state was observed for all Eti-OSILs, primarily for the dianionic ones, which leads to an inhibition of osteoclastogenesis and an increase in osteoblastogenesis. The observed effects resulted from differential modulation of intracellular signaling pathways by the Eti-OSILs in comparison with Etidronate. Hence, these results pave the way for the development of more efficient and bioavailable ionic formulations of bisphosphonates aiming to effectively modulate bone metabolism, particularly in the case of increased bone resorption.

New insights into molecular and cellular mechanisms of zoledronate in human osteosarcoma

Osteosarcoma is the most common primary malignant tumor of the skeleton in teenagers and young adults and continues to confer a generally poor prognosis in patients who do not respond to chemotherapy or who present with metastatic diseases at diagnosis. The nitrogen-containing zoledronate, the third generation bisphosphonate (BP), effectively inhibits osteoclastic bone resorption and is widely utilized in the treatment of metabolic and metastatic bone diseases nowadays. Owing to an acceptable safety profile and tolerability, zoledronate is the only BP currently approved for the prevention and treatment of skeletal relevant events in patients with metastatic bone lesions, especially bone metastases from advanced renal cell carcinoma and prostate cancer, and breast cancer, due to all solid malignancy. Moreover, zoledronate possesses diverse anti-osteosarcoma properties and may have potential to become an adjunctive treatment for high-grade osteosarcoma to enhance survival rates and to obliterate complications of the chemotherapy. Herein we highlighted the pharmacology of BPs and its underlying molecular mechanisms in osteoclasts and various cancer cells. We further provided the available literature on in vitro studies to illustrate the new insights into the intracellular molecular mechanisms of zoledronate in human osteosarcoma cell lines and in vivo animal models that led to the development and regulatory approval of zoledronate in patients with human osteosarcoma. This review also addresses clinical trials to focus on the efficacy of zoledronate on human osteosarcoma.

Denosumab versus bisphosphonates for the treatment of bone metastases from solid tumors: a systematic review

BACKGROUND

Bone metastases are highly prevalent in breast, prostate, lung and colon cancers. Their symptoms negatively affect quality of life and functionality and optimal management can mitigate these problems. There are two different targeted agents to treat them: bisphosphonates (pamidronate and zoledronic acid) and the monoclonal antibody denosumab. Estimates of cost-effectiveness are still mixed.

OBJECTIVE

To conduct a systematic review of economic studies that compares these two options.

METHOD

Literature search comprised eight databases and keywords for bone metastases, bisphosphonates, denosumab, and economic studies were used. Data were extracted regarding their methodologic characteristics and cost-effectiveness analyses. All studies were evaluated regarding to its methodological quality.

RESULTS

A total of 263 unique studies were retrieved and six met inclusion criteria. All studies were based on clinical trials and other existing literature data, and they had high methodological quality. Most found unfavorable cost-effectiveness for denosumab compared with zoledronic acid, with adjusted ICERS that ranged from $4638-87,354 per SRE avoided and from US$57,274-4.81 M. per QALY gained, which varied widely according to type of tumor, time horizon, among others. Results were sensitive to drug costs, time to first skeletal-related event (SRE), time horizon, and utility.

CONCLUSIONS

Denosumab had unfavorable cost-effectiveness compared with zoledronic acid in most of the included studies. New economic studies based on real-world data and longer time horizons comparing these therapeutic options are needed.

Osteolytic cancer cells induce vascular/axon guidance processes in the bone/bone marrow stroma

Prostate and breast cancers frequently metastasize to bone. The physiological bone homeostasis is perturbed once cancer cells proliferate at the bone metastatic site. Tumors are complex structures consisting of cancer cells and numerous stroma cells.

In this study, we show that osteolytic cancer cells (PC-3 and MDA-MB231) induce transcriptome changes in the bone/bone marrow microenvironment (stroma). This stroma transcriptome differs from the previously reported stroma transcriptome of osteoinductive cancer cells (VCaP). While the biological process “angiogenesis/vasculogenesis” is enriched in both transcriptomes, the “vascular/axon guidance” process is a unique process that characterizes the osteolytic stroma. In osteolytic bone metastasis, angiogenesis is denoted by vessel morphology and marker expression specific for arteries/arterioles. Interestingly, intra-tumoral neurite-like structures were in proximity to arteries. Additionally, we found that increased numbers of mesenchymal stem cells and vascular smooth muscle cells, expressing osteolytic cytokines and inhibitors of bone formation, contribute to the osteolytic bone phenotype.

Osteoinductive and osteolytic cancer cells induce different types of vessels, representing functionally different hematopoietic stem cell niches. This finding suggests different growth requirements of osteolytic and osteoinductive cancer cells and the need for a differential anti-angiogenic strategy to inhibit tumor growth in osteolytic and osteoblastic bone metastasis.

Emerging therapeutic targets in cancer induced bone disease: A focus on the peripheral type 2 cannabinoid receptor

Skeletal complications are a common cause of morbidity in patients with primary bone cancer and bone metastases. The type 2 cannabinoid (Cnr2) receptor is implicated in cancer, bone metabolism and pain perception. Emerging data have uncovered the role of Cnr2 in the regulation of tumour-bone cell interactions and suggest that agents that target Cnr2 in the skeleton have potential efficacy in the reduction of skeletal complications associated with cancer. This review aims to provide an overview of findings relating to the role of Cnr2 receptor in the regulation of skeletal tumour growth, osteolysis and bone pain, and highlights the many unanswered questions and unmet needs. This review argues that development and testing of peripherally-acting, tumour-, Cnr2-selective ligands in preclinical models of metastatic cancer will pave the way for future research that will advance our knowledge about the basic mechanism(s) by which the endocannabinoid system regulate cancer metastasis, stimulate the development of a safer cannabis-based therapy for the treatment of cancer and provide policy makers with powerful tools to assess the science and therapeutic potential of cannabinoid-based therapy. Thus, offering the prospect of identifying selective Cnr2 ligands, as novel, alternative to cannabis herbal extracts for the treatment of advanced cancer patients.

Assessment and monitoring of patients receiving chemotherapy for multiple myeloma: strategies to improve outcomes

Improved understanding as to the biology of multiple myeloma (MM) and the bone marrow microenvironment has led to the development of new drugs to treat MM. This explosion of new and highly effective drugs has led to dramatic advances in the management of MM and underscores the need for supportive care. Impressive and deep response rates to chemotherapy, monoclonal antibodies, and small molecule drugs provide hope of a cure or prolonged remission for the majority of individuals. For most patients, long-term, continuous therapy is often required to suppress the malignant plasma cell clone, thus requiring clinicians to become more astute in assessment, monitoring, and intervention of side effects as well as monitoring response to therapy. Appropriate diagnosis and monitoring strategies are essential to ensure that patients receive the appropriate chemotherapy and supportive therapy at relapse, and that side effects are appropriately managed to allow for continued therapy and adherence to the regimen. Multiple drugs with complex regimens are currently available with varying side effect profiles. Knowledge of the drugs used to treat MM and the common adverse events will allow for preventative strategies to mitigate adverse events and prompt intervention. The purpose of this paper is to review updates in the diagnosis and management of MM, and to provide strategies for assessment and monitoring of patients receiving chemotherapy for MM.

Two cases of gastrointestinal stromal tumor of the small intestine with liver and bone metastasis

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. These tumors most commonly occur in the stomach (60%), jejunum and ileum (30%). Metastasis is characteristically the malignant behavior of the GISTs. GISTs most frequently metastasize to the liver and peritoneum, whereas bone and lung metastases are uncommon sites. Here, we described two cases of bone and liver metastases in patients with advanced GISTs. Both of them showed liver metastasis at disease presentation and bone metastasis in early time after the diagnosis. Bone metastases involved the lumber spine and right femur in first patient and L2 vertebral body in the second case. All of the lesions presented a lytic pattern. These cases are presented because of the rare incidence of bone metastasis to femur and vertebral bodies. More attention should be paid to the diagnosis of bone metastases from GISTs in clinical practice despite the shortage of available data on the sensitivity and specificity of bone scintigraphy and PET-CT.

EGFR mutations are associated with higher incidence of distant metastases and smaller tumor size in patients with non-small-cell lung cancer based on PET/CT scan

The study aimed to explore the correlation of epidermal growth factor receptor (EGFR) mutation with tumor node metastasis (TNM) stage in patients with non-small-cell lung cancer (NSCLC) who underwent positron emission tomography/computed tomography (PET/CT) scan. Patients diagnosed with NSCLC who underwent EGFR mutation status testing and PET/CT or PET/CT plus brain magnetic resonance imaging scan at initial diagnosis in Nanfang Hospital between July 2010 and June 2014 were consecutively enrolled. The correlation of EGFR mutation status with TNM stage and distant metastasis organs including brain, bone, liver, pleural, adrenals and contralateral lobe of lung were analyzed. A total of 401 patients were enrolled. Tumor size in EGFR mutation group was significantly smaller than the wild-type group (P < 0.001). Further, patients with EGFR mutations were demonstrated significantly more frequent in patients with distant metastasis than non-metastasis (45.7 vs 32.2 %, P = 0.007). The rates of bone (32.2 vs 22.8 %, P = 0.007) and brain (16.3 vs 9.4 %, P = 0.008) metastasis were significantly higher in EGFR mutation group than the wild-type group. In the subgroup of 199 metastatic NSCLC patients, patients with EGFR mutation were significantly associated with a smaller tumor size (P = 0.013) and earlier N stage (P = 0.033). Of note, compared with the EGFR wild-type group, patients had a higher likelihood of developing brain plus bone metastases at initial diagnosis of EGFR mutation group (20.9 vs 7.5 %, P = 0.018). Taken together, we identify that EGFR mutations might associate with more aggressive tumor progression than the wild types in NSCLC. In addition, patients with tumor having EGFR mutation had a smaller tumor size than without mutation.

Zoledronic acid in the treatment of metastatic breast cancer

Bone is the most common location of metastatic disease. Approximately 80% of all bone metastases are observed in patients with breast or prostate tumours and are responsible for more than 300 000 deaths every year. Treatment of malignant bone disease with bisphosphonates has been shown to reduce bone events and delay their onset, and several reviews and meta-analyses have confirmed the benefit of these drugs in controlling bone metastases. Zoledronic acid is a bisphosphonate that has been shown to delay or prevent the development of skeletal-related events in patients with bone metastases. Furthermore, compared with other bisphosphonates, zoledronic acid has also shown better pain control and various studies also suggest an improvement in quality of life, although with no impact on overall survival. The duration and optimal regimen for long-term zoledronic acid therapy have not yet been defined, but some studies suggest that continuing zoledronic acid therapy for more than 2 years could also extend its beneficial effect.

Adjuvant bisphosphonates in breast cancer: has the time come?

SUMMARY Bone metabolism is highly affected by changes in ovarian function, which is a common consequence of the treatment of breast cancer patients. Osteopenia and osteoporosis increase the risk of fractures, which are associated with profound loss in quality of life. Bisphosphonates are used with the objective of preventing bone loss in patients with osteoporosis, but data suggest that agents such as zoledronic acid might play a role in the prevention of metastatic disease and therefore have been evaluated in numerous randomized trials in the adjuvant setting. This review article will discuss and analyze the available data regarding the use of bisphosphonates in the adjuvant setting for breast cancer patients. It will focus on the use of bisphosphonates as anticancer agents, but will also discuss the use of these agents for the prevention of bone loss.

CCN3 promotes prostate cancer bone metastasis by modulating the tumor-bone microenvironment through RANKL-dependent pathway

Bone metastasis in patient with advanced-stage prostate cancer, the most commonly diagnosed malignancy in Western countries, increases the risk of intractable bone pain. The nephroblastoma overexpressed (NOV/CCN3) gene, a member of the CCN gene family, is responsible for the secretion of CCN3, a matrix-associated protein involved in many cellular functions. However, the role of CCN3 in prostate cancer metastasis to bone is poorly understood. CCN3 was found to be highly expressed in bone metastasis patients and positively correlated with malignancy in human prostate cancer cells. Prostate cancer conditioned medium-induced osteoclast differentiation was inhibited by neutralizing antibody against CCN3. Specifically, CCN3 was found to induce osteoclastogenesis through the receptor activator of NF-κB ligand (RANKL)-dependent pathway, and the focal adhesion kinase/Akt/p38/NF-κB signal pathway was found to be involved in CCN3-mediated receptor activator of NF-κB expression and RANKL-dependent osteoclastogenesis. In contrast, osteoblasts were observed to play an important role in osteoclast differentiation by paracrine manner, with treatment of osteoblasts with CCN3 found to change the RANKL (osteoclastogenesis):OPG (antiosteoclastogenesis) ratio. Compared with parental PC3 cells, highly invasive PC3-I3 cells markedly enhanced osteoclast activity and bone metastasis in vivo. These results indicate that CCN3 can be used as a novel therapeutic target in the prevention of bone metastasis of prostate cancer.

Adjuvant therapy with zoledronic acid in patients with breast cancer: a systematic review and meta-analysis

BACKGROUND

The purpose of the study was to estimate the impact on survival and fracture rates of the use of zoledronic acid versus no use (or delayed use) in the adjuvant treatment of patients with early-stage (stages I-III) breast cancer.

MATERIALS AND METHODS

We performed a systematic review and meta-analysis of randomized clinical trials. Trials were located through PubMed, ISI, Cochrane Library, and major cancer scientific meeting searches. All trials that randomized patients with primary breast cancer to undergo adjuvant treatment with zoledronic acid versus nonuse, placebo, or delayed use of zoledronic acid as treatment to individuals who develop osteoporosis were considered eligible. Standard meta-analytic procedures were used to analyze the study outcomes.

RESULTS

Fifteen studies were considered eligible and were further analyzed. The use of zoledronic acid resulted in a statistically significant better overall survival outcome (five studies, 6,414 patients; hazard ratio [HR], 0.81; 95% confidence interval [CI], 0.70-0.94). No significant differences were found for the disease-free survival outcome (seven studies, 7,541 patients; HR, 0.86; 95% CI, 0.70-1.06) or incidence of bone metastases (seven studies, 7,543 patients; odds ratio [OR], 0.94; 95% CI, 0.64-1.37). Treatment with zoledronic acid led to a significantly lower overall fracture rate (OR, 0.78; 95% CI, 0.63-0.96). Finally, the rate of osteonecrosis of the jaw was 0.52%.

CONCLUSION

Zoledronic acid as adjuvant therapy in breast cancer patients appears to not only reduce the fracture risk but also offer a survival benefit over placebo or no treatment.

Zoledronate for metastatic bone disease and pain: a meta-analysis of randomized clinical trials

BACKGROUND

Randomized controlled trials (RCTs) have reported different results when using zoledronate to treat skeletal-related events (SREs) and bone pain in patients with metastatic bone disease (MBD), and few have looked at the risks and benefits of long-term use of the drug. This meta-analysis aimed to investigate the efficacy and safety of zoledronate to treat MBD in the short and long-term.

METHODS

PubMed, EMBASE, and the Cochrane Library were searched to identify RCTs evaluating zoledronate for MBD. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated.

RESULTS

Twelve RCTs involving 4,450 patients were included in the meta-analysis. Zoledronate decreased the risk of developing SREs compared with placebo (RR 0.75, 95% CI 0.69 to 0.81, P < 0.001). Zoledronate consistently reduced the brief pain inventory (BPI) below baseline compared with placebo at 3, 12, and 24 months. In addition, the likelihood of experiencing a bone pain event was significantly lower in the zoledronate group than in the placebo group (RR 0.83, 95% CI 0.76 to 0.89, P < 0.001). While the two groups did not differ significantly in the incidence of nausea(RR = 1.07, 95% CI 0.96 to 1.19, P = 0.250), emesis (RR 0.94, 95% CI 0.81 to 1.09, P = 0.420), or adverse renal events (RR 1.41, 95% CI 0.94 to 2.11, P = 0.09), the zoledronate group showed a significantly higher relative risk of pyrexia (RR 1.43, 95% CI 1.20 to 1.70, P < 0.001), fatigue (RR 1.26, 95% CI 1.10 to 1.43, P < 0.001), and anemia (RR 1.33, 95% CI 1.14 to 1.55, P < 0.001).

CONCLUSION

Compared to placebo, zoledronate significantly reduced the incidence of bone pain and SREs in patients with MBD for periods as long as 24 months. In addition, zoledronate is generally well tolerated over this long period.

Reduced colon cancer incidence and mortality in postmenopausal women treated with an oral bisphosphonate--Danish National Register Based Cohort Study

In this Danish national register-based cohort study, we examined the effects of alendronate on the development of colon cancers and survival. The incidence of colon cancer and mortality rate, once colon cancer had been diagnosed, were lower in patients treated with alendronate, posing the question whether alendronate acts as chemopreventive.

INTRODUCTION

When bisphosphonates are given by mouth, around 99% remains non-absorbed in the intestine. Based on their biochemical actions, we predicted that oral bisphosphonates might prevent colon cancers.

METHODS

This is a Danish national register-based cohort study. We identified 30,606 women aged 50+, mean age 71.9 years, who had not previously taken treatments for osteoporosis, who began to take alendronate in 1996-2005, and assigned 124,424 individually age- and gender-matched control subjects. The main outcome measure was colorectal cancers incidence and post-diagnosis survival in patients taking oral alendronate for osteoporosis.

RESULTS

Cox proportional hazards analysis of death due to colon cancer showed lower risk in alendronate users, crude hazard ratio (HR) 0.69 (95% CI 0.59-0.81) with an adjusted HR of 0.62 (95% CI 0.52-0.72). The reduction in risk comprised both a lower incidence of colon cancer-adjusted HR 0.69 (95% CI 0.60-0.79) and a lower mortality once colon cancer had been diagnosed, adjusted HR 0.82 (95% CI 0.70-0.97). Weekly alendronate was associated with a greater risk reduction than daily alendronate. The main findings were unaffected by excluding patients from the analysis who had pulmonary disease, a major co-morbid condition in users of alendronate and an important cause of death.

CONCLUSIONS

The risk of overall deaths from cancer and in particular death caused by colon cancer was significantly and substantially decreased (40%) in patients treated with alendronate, with survival curves deviating progressively after 2 years. Also, the incidence of colon cancer was lower in those patients.

Bisphosphonates and other bone agents for breast cancer

BACKGROUND

Bone is the most common site of metastatic disease associated with breast cancer (BC). Bisphosphonates inhibit osteoclast-mediated bone resorption, and novel targeted therapies such as denosumab, inhibit key pathways in the vicious cycle of bone metastases.

OBJECTIVES

To assess the effect of bisphosphonates on skeletal-related events (SREs), bone pain, quality of life (QoL), recurrence and survival in women with breast cancer with bone metastases (BCBM), advanced breast cancer (ABC) without clinical evidence of bone metastases and early breast cancer (EBC).To assess the effect of denosumab on SREs, bone pain and (QoL) in women with (BCBM).

SEARCH METHODS

We searched the Specialised Register maintained by the Cochrane Breast Cancer Group (CBCGSR), MEDLINE, EMBASE and the WHO International Cancer Trials Registry Platform (WHO ICTRP) on 30 April 2011. We conducted additional handsearching of journals and proceedings of key meetings.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing: (a) bisphosphonates and control, or different bisphosphonates in women with BCBM; (b) denosumab and bisphosphonates in women with BCBM; (c) bisphosphonates and control in women with ABC; (d) bisphosphonates and control in women with EBC; and (e) early versus delayed bisphosphonate treatment in women with EBC.

DATA COLLECTION AND ANALYSIS

Two review authors (MW and NP) independently assessed the trials and extracted the data. We collected toxicity information from the trials.

MAIN RESULTS

We included thirty-four RCTs. In nine studies (2806 patients with BCBM), comparing bisphosphonates with placebo or no bisphosphonates, bisphosphonates reduced the SRE risk by 15% (risk ratio (RR) 0.85; 95% confidence interval (CI) 0.77 to 0.94; P = 0.001). This benefit was most certain with intravenous (i.v.) zoledronic acid (4 mg) (RR 0.59; 95% CI 0.42 to 0.82); i.v. pamidronate (90 mg) (RR 0.77; 95% CI 0.69 to 0.87); and i.v. ibandronate (RR 0.80; 95% CI 0.67 to 0.96). A direct comparison of i.v. zoledronic acid and i.v. pamidronate confirmed at least equivalent efficacy in a single large study. In three studies (3405 patients with BCBM), compared with bisphosphonates, subcutaneous (s.c.) denosumab was more effective in reducing the risk of SREs (RR 0.78; 95% CI 0.72 to 0.85; P < 0.00001).Bisphosphonates reduced the SRE rate in 12 studies (median reduction 28%, range 14% to 48%), with statistically significant reductions reported in 10 studies. Women with BCBM treated with bisphosphonates showed significant delays in the median time to SREs. Compared with placebo or no bisphosphonates, treatment with bisphosphonates significantly improved bone pain in six out of eleven studies. Improvements in global QoL with bisphosphonates compared to placebo were reported in two out of five studies (both ibandronate studies). Treatment with bisphosphonates did not appear to affect survival in women with BCBM. Compared to i.v. zoledronic acid, denosumab also significantly reduced the SRE rate, delayed the time to SREs and prolonged the time in developing pain for patients with no or mild pain at baseline; but there was no difference in survival between patients treated with denosumab and zoledronic acid.Bisphosphonates in women with ABC without clinically evident bone metastases did not reduce the incidence of bone metastases, or improve survival in three studies (320 patients).In seven studies (7847 patients with EBC), currently there is no evidence supporting bisphosphonates in reducing the incidence of bone metastases compared to no bisphosphonates (RR 0.94; 95% CI 0.82 to 1.07; P = 0.36). In three studies (2190 patients with EBC), early bisphosphonate treatment also did not significantly reduce the incidence of bone metastases compared to delayed bisphosphonate treatment (RR 0.73; 95% CI 0.40 to 1.33; P = 0.31). Currently, there is insufficient evidence to make a conclusion about the role of adjuvant bisphosphonates in reducing visceral metastases, locoregional recurrence and total recurrence, or improving survival. There was strong heterogeneity in EBC studies examining the outcomes of total recurrence and survival.Reported toxicity was generally mild. Renal toxicity and osteonecrosis of the jaw (ONJ) have been identified as potential problems with bisphosphonate use. ONJ was reported at similar rates for patients on denosumab compared to zoledronic acid. This highlighted a need for maintaining good oral care, prior to and during treatment, for patients who received long-term bone agents.

AUTHORS' CONCLUSIONS

In women with clinically evident BCBM, bisphosphonates (oral and i.v.) and denosumab (s.c.) reduced the risk of developing SREs, as well as delaying the time to SREs. Some bisphosphonates may also reduce bone pain and may improve QoL. The optimal timing and duration of treatment for patients with BCBM remains uncertain. There is currently insufficient evidence to support the routine use of bisphosphonates as adjuvant treatment for patients with EBC. However, a number of large clinical trials investigating bisphosphonates in EBC have completed accrual and are awaiting results.

Three cases of bone metastases in patients with gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are rare, but represent the most common mesenchymal neoplasms of the gastrointestinal tract. Tumor resection is the treatment of choice for localized disease. Tyrosine kinase inhibitors (imatinib, sunitinib) are the standard therapy for metastatic or unresectable GISTs. GISTs usually metastasize to the liver and peritoneum. Bone metastases are uncommon. We describe three cases of bone metastases in patients with advanced GISTs: two women (82 and 54 years of age), and one man (62 years of age). Bones metastases involved the spine, pelvis and ribs in one patient, multiple vertebral bodies and pelvis in one, and the spine and iliac wings in the third case. The lesions presented a lytic pattern in all cases. Two patients presented with multiple bone metastases at the time of initial diagnosis and one patient after seven years during the follow-up period. This report describes the diagnosis and treatment of the lesions and may help clinicians to manage bones metastases in GIST patients.

Advances in the biology and treatment of bone disease in multiple myeloma

Osteolytic bone disease is pathognomonic of multiple myeloma (MM) and affects more than 80% of patients. Bone disease results in skeletal-related events (SRE) such as vertebral compression fractures, which may cause cord compression, hypercalcemia, pathologic fractures that require radiation or surgical fixation, and severe pain. All of these not only result in a negative impact on quality of life but also adversely impact overall survival. Osteolytic disease is a consequence of increased osteoclast (OC) activation along with osteoblast (OB) inhibition, resulting in altered bone remodeling. OC number and activity are increased in MM via cytokine deregulation within the bone marrow (BM) milieu, whereas negative regulators of OB differentiation suppress bone formation. Bisphosphonates are a well-established treatment of myeloma-related skeletal disease and are the current standard of care. However, complications arising from their long-term use have prompted studies of schedule optimization and alternate strategies. Several novel agents are currently under investigation for their positive effect on bone remodeling via OC inhibition. The identification of negative regulators of OB differentiation has prompted the use of anabolic agents. In addition to restoring bone remodeling, these drugs may inhibit tumor growth in vivo. Future studies will look to combine or sequence all of these agents with the goal of not only alleviating morbidity from bone disease but also capitalizing on the resultant antitumor activity.

The relationship between the chemistry and biological activity of the bisphosphonates

The ability of bisphosphonates ((HO)(2)P(O)CR(1)R(2)P(O)(OH)(2)) to inhibit bone resorption has been known since the 1960s, but it is only recently that a detailed molecular understanding of the relationship between chemical structures and biological activity has begun to emerge. The early development of chemistry in this area was largely empirical and based on modifying R(2) groups in a variety of ways. Apart from the general ability of bisphosphonates to chelate Ca(2+) and thus target the calcium phosphate mineral component of bone, attempts to refine clear structure-activity relationships had led to ambiguous or seemingly contradictory results. However, there was increasing evidence for cellular effects, and eventually the earliest bisphosphonate drugs, such as clodronate (R(1)=R(2)=Cl) and etidronate (R(1)=OH, R(2)=CH(3)), were shown to exert intracellular actions via the formation in vivo of drug derivatives of ATP. The observation that pamidronate, a bisphosphonate with R(1)=OH and R(2)=CH(2)CH(2)NH(2), exhibited higher potency than previously known bisphosphonate drugs represented the first step towards the later recognition of the critical importance of having nitrogen in the R(2) side chain. The synthesis and biological evaluation of a large number of nitrogen-containing bisphosphonates took place particularly in the 1980s, but still with an incomplete understanding of their structure-activity relationships. A major advance was the discovery that the anti-resorptive effects of the nitrogen-containing bisphosphonates (including alendronate, risedronate, ibandronate, and zoledronate) on osteoclasts appear to result from their potency as inhibitors of the enzyme farnesyl pyrophosphate synthase (FPPS), a key branch-point enzyme in the mevalonate pathway. FPPS generates isoprenoid lipids utilized in sterol synthesis and for the post-translational modification of small GTP-binding proteins essential for osteoclast function. Effects on other cellular targets, such as osteocytes, may also be important. Over the years many hundreds of bisphosphonates have been synthesized and studied. Interest in expanding the structural scope of the bisphosphonate class has also motivated new approaches to the chemical synthesis of these compounds. Recent chemical innovations include the synthesis of fluorescently labeled bisphosphonates, which has enabled studies of the biodistribution of these drugs. As a class, bisphosphonates share common properties. However, as with other classes of drugs, there are chemical, biochemical, and pharmacological differences among the individual compounds. Differences in mineral binding affinities among bisphosphonates influence their differential distribution within bone, their biological potency, and their duration of action. The overall pharmacological effects of bisphosphonates on bone, therefore, appear to depend upon these two key properties of affinity for bone mineral and inhibitory effects on osteoclasts. The relative contributions of these properties differ among individual bisphosphonates and help determine their clinical behavior and effectiveness.

Bisphosphonates: the first 40 years

The first full publications on the biological effects of the diphosphonates, later renamed bisphosphonates, appeared in 1969, so it is timely after 40years to review the history of their development and their impact on clinical medicine. This special issue of BONE contains a series of review articles covering the basic science and clinical aspects of these drugs, written by some of many scientists who have participated in the advances made in this field. The discovery and development of the bisphosphonates (BPs) as a major class of drugs for the treatment of bone diseases has been a fascinating story, and is a paradigm of a successful journey from 'bench to bedside'. Bisphosphonates are chemically stable analogues of inorganic pyrophosphate (PPi), and it was studies on the role of PPi as the body's natural 'water softener' in the control of soft tissue and skeletal mineralisation that led to the need to find inhibitors of calcification that would resist hydrolysis by alkaline phosphatase. The observation that PPi and BPs could not only retard the growth but also the dissolution of hydroxyapatite crystals prompted studies on their ability to inhibit bone resorption. Although PPi was unable to do this, BPs turned out to be remarkably effective inhibitors of bone resorption, both in vitro and in vivo experimental systems, and eventually in humans. As ever more potent BPs were synthesised and studied, it became apparent that physico-chemical effects were insufficient to explain their biological effects, and that cellular actions must be involved. Despite many attempts, it was not until the 1990s that their biochemical actions were elucidated. It is now clear that bisphosphonates inhibit bone resorption by being selectively taken up and adsorbed to mineral surfaces in bone, where they interfere with the action of the bone-resorbing osteoclasts. Bisphosphonates are internalised by osteoclasts and interfere with specific biochemical processes. Bisphosphonates can be classified into at least two groups with different molecular modes of action. The simpler non-nitrogen containing bisphosphonates (such as etidronate and clodronate) can be metabolically incorporated into non-hydrolysable analogues of ATP, which interfere with ATP-dependent intracellular pathways. The more potent, nitrogen-containing bisphosphonates (including pamidronate, alendronate, risedronate, ibandronate and zoledronate) are not metabolised in this way but inhibit key enzymes of the mevalonate/cholesterol biosynthetic pathway. The major enzyme target for bisphosphonates is farnesyl pyrophosphate synthase (FPPS), and the crystal structure elucidated for this enzyme reveals how BPs bind to and inhibit at the active site via their critical N atoms. Inhibition of FPPS prevents the biosynthesis of isoprenoid compounds (notably farnesol and geranylgeraniol) that are required for the post-translational prenylation of small GTP-binding proteins (which are also GTPases) such as rab, rho and rac, which are essential for intracellular signalling events within osteoclasts. The accumulation of the upstream metabolite, isopentenyl pyrophosphate (IPP), as a result of inhibition of FPPS may be responsible for immunomodulatory effects on gamma delta (γδ) T cells, and can also lead to production of another ATP metabolite called ApppI, which has intracellular actions. Effects on other cellular targets, such as osteocytes, may also be important. Over the years many hundreds of BPs have been made, and more than a dozen have been studied in man. As reviewed elsewhere in this issue, bisphosphonates are established as the treatments of choice for various diseases of excessive bone resorption, including Paget's disease of bone, the skeletal complications of malignancy, and osteoporosis. Several of the leading BPs have achieved 'block-buster' status with annual sales in excess of a billion dollars. As a class, BPs share properties in common. However, as with other classes of drugs, there are obvious chemical, biochemical, and pharmacological differences among the various BPs. Each BP has a unique profile in terms of mineral binding and cellular effects that may help to explain potential clinical differences among the BPs. Even though many of the well-established BPs have come or are coming to the end of their patent life, their use as cheaper generic drugs is likely to continue for many years to come. Furthermore in many areas, e.g. in cancer therapy, the way they are used is not yet optimised. New 'designer' BPs continue to be made, and there are several interesting potential applications in other areas of medicine, with unmet medical needs still to be fulfilled. The adventure that began in Davos more than 40 years ago is not yet over.

Hospital resource utilization and treatment cost of skeletal-related events in patients with metastatic breast or prostate cancer: estimation for the Portuguese National Health System

BACKGROUND

Skeletal-related events (SREs) occur frequently in patients with bone metastases as a result of breast (BC) and prostate (PC) cancers. They increase both morbidity and mortality and lead to extensive health-care resource utilization.

METHODS

Health care resource utilization by BC/PC patients with at least one SRE during the preceding 12 months was assessed through retrospective chart review. SRE-treatment costs were estimated using the Portuguese Ministry of Health cost database and analyzed using generalized linear models.

RESULTS

This study included 152 patients from nine hospitals. The mean (SD) annual SRE-treatment cost per patient was €5963 (€3646) and €5711 (€4347), for BC (n=121) and PC (n=31) patients, respectively. Mean cost per single episode ranged between €1485 (radiotherapy) and €13,203 (spinal cord compression). Early onset of bone metastasis (P = 0.03) and diagnosis of bone metastases at or after the occurrence of the first SRE (P < 0.001) were associated with higher SRE-treatment costs.

CONCLUSION

These results reveal the high hospital SRE-treatment costs, highlighting the need for early diagnosis and treatment, and identify key factors determining the economic value of therapies for patients with skeletal metastases.

Emerging therapies in metastatic bone pain

INTRODUCTION

Current treatment for metastatic bone pain is mainly palliative. Recent insights into the molecular mechanisms involved in bone metastases have led to the identification of promising therapeutic targets. This review offers an update of preclinical and clinical data on new drugs for metastatic bone pain.

AREAS COVERED

Biphosphonates are the gold standard of bone-targeted therapy in bone metastases, for their anti-resorptive and analgesic effects. New drugs aim at breaking the 'vicious cycle' of bone metastatic disease, due to the bidirectional interaction between cancer cells and bone microenvironment. Osteoprotegerin, RANK/RANKL interaction, cathepsin K, the Wnt/beta-catenin pathway and sclerostin are emerging targets for modulation of cancer-induced bone desorption. Other promising targets are those expressed in cancer cells that metastasize to bone, including Src, nerve growth factor, endothelin A, TGF-beta and CXCR4. Interesting therapeutic options include targets on nociceptors that innervate the bone, such as TPRV1, Trk and cannabinoid receptors.

EXPERT OPINION

Emerging therapies promise, in the next 10 years, a significant expansion in the array of therapeutic options for bone metastases. Most of these drugs are still in an early phase of development. Further clinical trials are needed to support the evidence of their efficacy and tolerability profile.

The role of bisphosphonates in multiple myeloma: mechanisms, side effects, and the future

Zoledronic acid and pamidronate are two potent anticatabolic nitrogen-containing bisphosphonates (BPs) used extensively in diseases with high bone turnover such as multiple myeloma (MM). In this review we focus on their biology and their current and future use in MM, and highlight some of the most common and emerging side effects. Although the primary target cells for BPs are osteoclasts, new insights suggest other cell types of the bone microenvironment as possible targets, including osteoblasts, endothelial cells, immune cells, and cancer cells. Here, we focus on the current guidelines for the use of BPs in MM and address side effects such as renal toxicity, osteonecrosis of the jaw, and low-energy fractures. Finally, we approach the future of BP use in MM in the context of other bone-targeted agents, evaluating ongoing clinical trials addressing alternate dosing and schedules of BP administration in MM patients.

The use of zoledronic acid in pediatric cancer patients

BACKGROUND

The third generation bisphosphonate zoledronic acid has demonstrated efficacy in reducing skeletal-related events in adult patients with multiple cancer types that have skeletal disease. The use of zoledronic acid in pediatric oncology patients with bone metastases for the purpose of reducing pain, improving bone strength and altering the progression of metastatic disease has not been thoroughly evaluated.

PROCEDURE

From October 2005 to December 2008, 19 patients at the Aflac Cancer Center received one or more doses of zoledronic acid as part of their therapy. A retrospective review of these patients was performed and information was collected including indication for treatment, toxicities, and outcomes.

RESULTS

Most patients (n = 15) received zoledronic acid following relapse of their malignancy with metastatic disease present in one or more bony sites. Hypocalcemia and hypophosphatemia were frequent, but did not result in clinical symptoms. More significant toxicities associated with zoledronic acid, including clinically apparent renal insufficiency and osteonecrosis of the jaw, were not seen. Overall, zoledronic acid was well tolerated in this population.

CONCLUSIONS

The benefits of zoledronic acid seen in randomized trials of adults with bone metastases have sparked interest in its use for children with metastatic cancer. The administration of zoledronic acid in pediatric oncology appears safe, and may result in improved bone strength and pain control. Further evaluation is warranted to prospectively evaluate its efficacy and long-term safety in pediatric patients with cancer and skeletal metastases.

Osteoclast activity and subtypes as a function of physiology and pathology--implications for future treatments of osteoporosis

Osteoclasts have traditionally been associated exclusively with catabolic functions that are a prerequisite for bone resorption. However, emerging data suggest that osteoclasts also carry out functions that are important for optimal bone formation and bone quality. Moreover, recent findings indicate that osteoclasts have different subtypes depending on their location, genotype, and possibly in response to drug intervention. The aim of the current review is to describe the subtypes of osteoclasts in four different settings: 1) physiological, in relation to turnover of different bone types; 2) pathological, as exemplified by monogenomic disorders; 3) pathological, as identified by different disorders; and 4) in drug-induced situations. The profiles of these subtypes strongly suggest that these osteoclasts belong to a heterogeneous cell population, namely, a diverse macrophage-associated cell type with bone catabolic and anabolic functions that are dependent on both local and systemic parameters. Further insight into these osteoclast subtypes may be important for understanding cell-cell communication in the bone microenvironment, treatment effects, and ultimately bone quality.

The preferences and experiences of different bisphosphonate treatments in women with breast cancer

OBJECTIVE

The objective of this study was to examine women's experiences with oral and intravenous (i.v.) bisphosphonate therapy, the impact that treatment had on bone pain and Quality of Life (QoL), and their preferences if choice were available between oral and i.v. administration.

METHODS

This was a prospective study of women with metastatic breast cancer receiving either oral or i.v. bisphosphonate therapy. Semi-structured interview techniques and QoL questionnaires were employed. Participants in the study were interviewed three times, once in person and twice by telephone.

RESULTS

A total of 79 patients from eight UK hospitals participated in the study; 35 were receiving oral bisphosphonate medication and 44 i.v. treatments. Self-reported adherence to oral therapy was good although 21% had chosen not to take their drugs at some time. Most had adapted their lifestyle to accommodate oral therapy with 29/37(74%) completely satisfied. However 9/37(24%) expressed dissatisfaction with constraints especially the time required to stand upright after taking their tablets. By 6 months 23/25 (91%) of patients receiving (i.v.) therapies were generally satisfied with the frequency and 22/25 (88%) with the convenience especially if given concurrently with chemotherapy. Overall 25/54 (46%) patients reported improved bone pain scores on the validated FACT-BP scale from baseline to 6 months.

CONCLUSIONS

Both oral and i.v. therapies have disadvantages but were acceptable to most patients some of whom had reduced bone pain over time. More data regarding acceptability, adherence, and patients' preference for bisphosphonate therapies are required. Until randomised trials demonstrate superior efficacy for one mode of bisphosphonate therapy over another, we suggest offering patients a choice of bisphosphonate therapy.