Bisphosphonates for malignancy-related bone disease: current status, future developments

Alterations in macrophage polarization in the craniofacial and extracranial skeleton after zoledronate application and surgical interventions - an in vivo experiment

Purpose

Medication-related osteonecrosis occurs exclusively in the jaw bones. However, the exact pathogenesis of medication-related osteonecrosis of the jaw (MRONJ) and the unique predisposition of the jaw bones have not been elucidated, making its treatment a challenge. Recent evidence indicates that macrophages might play a pivotal role in MRONJ pathogenesis. The aim of the present study was to compare the macrophage populations between the craniofacial and extracranial skeleton and to investigate the changes induced by zoledronate (Zol) application and surgical interventions.

Materials and methods

An in vivo experiment was performed. 120 wistar rats were randomized to 4 groups (G1, G2, G3, G4). G1 served as an untreated control group. G2 and G4 received Zol injections for 8 weeks. Afterwards, the right lower molar of the animals from G3 and G4 was extracted and the right tibia osteotomized followed by osteosynthesis. Tissue samples were taken from the extraction socket and the tibia fracture at fixed time points. Immunohistochemistry was conducted to determine the labeling indexes of CD68+ and CD163+ macrophages.

Results

Comparing the mandible and the tibia, we observed a significantly higher number of macrophages and a heightened pro-inflammatory environment in the mandible compared to the tibia. Tooth extraction caused an increase of the overall number of macrophages and a shift toward a more pro-inflammatory microenvironment in the mandible. Zol application amplified this effect.

Conclusion

Our results indicate fundamental immunological differences between the jaw bone and the tibia, which might be a reason for the unique predisposition for MRONJ in the jaw bones. The more pro-inflammatory environment after Zol application and tooth extraction might contribute to the pathogenesis of MRONJ. Targeting macrophages might represent an attractive strategy to prevent MRONJ and improve therapy. In addition, our results support the hypothesis of an anti-tumoral and anti-metastatic effect induced by BPs. However, further studies are needed to delineate the mechanisms and specify the contributions of the various macrophage phenotypes.

Bisphosphonate-Based Conjugates and Derivatives as Potential Therapeutic Agents in Osteoporosis, Bone Cancer and Metastatic Bone Cancer

Metastatic bone cancer occurs in every type of cancer but is prevalent in lung, breast, and prostate cancers. These metastases can cause extensive morbidity, including a range of skeletal-related events, often painful and linked with substantial hospital resource usage. The treatment used is a combination of chemotherapy and surgery. However, anticancer drugs are still limited due to severe side effects, drug resistance, poor blood supply, and non-specific drug uptake, necessitating high toxic doses. Bisphosphonates are the main class of drugs utilized to inhibit metastatic bone cancer. It is also used for the treatment of osteoporosis and other bone diseases. However, bisphosphonate also suffers from serious side effects. Thus, there is a serious need to develop bisphosphonate conjugates with promising therapeutic outcomes for treating metastatic bone cancer and osteoporosis. This review article focuses on the biological outcomes of designed bisphosphonate-based conjugates for the treatment of metastatic bone cancer and osteoporosis.

Medication-Related Osteonecrosis of the Jaws

Medication-related osteonecrosis of the jaw is an oral complication in cancer patients being treated with either antiresorptive or antiangiogenic drugs. The first reports of MRONJ were published in 2003. Hundreds of manuscripts have been published in the medical and dental literature describing the complication, clinical and radiographic signs and symptoms, possible pathophysiology, and management. Despite this extensive literature, the pathobiological mechanisms by which medication-related osteonecrosis of the jaw develops have not yet been fully delineated. The aim of this manuscript is to present current knowledge about the complication ragarding to the definition, known risk factors, and clinical management recommendations. Based on this current state of the science, we also propose research directions that have potential to enhance the management of future oncology patients who are receiving these agents.

Clinical and translational pharmacology of drugs for the prevention and treatment of bone metastases and cancer-induced bone loss

Bone disease is a frequent event in cancer patients, both due to cancer spread to bone and to cancer therapies. Bone is the organ most frequently affected by metastatic disease when considering the two most frequent cancers in the Western world (breast and prostate cancers). Bone metastases can have a substantial detrimental effect on patients' quality of life, as well as significant morbidity due to complications collectively known as skeletal-related events (SREs), which include hypercalcaemia, pathological fractures, spinal cord compression, and need of radiotherapy or surgery to the bone. These have been successfully mitigated with the development of bone-targeted agents (BTAs; bisphosphonates and denosumab), focused on inhibiting osteoclast activity. The potential direct antitumour effect of bisphosphonates, as well as the impact of osteoclast inhibition with subsequent decrease in bone metabolism, have also propelled investigation on the role of BTAs in preventing cancer relapse in bone. In this review, the authors aimed to discuss the role of BTAs in the treatment and prevention of bone metastases, as well as their potential value in preventing cancer treatment-induced bone loss (CTIBL). The review will focus on breast and prostate cancers, with the aim of providing the most relevant clinical data emerging from bench to bedside translational research in the field of cancer-induced bone disease.

Sclerostin Modulation Holds Promise for Dental Indications

Sclerostin modulation is a novel therapeutic bone regulation strategy. The anti-sclerostin drugs, proposed in medicine for skeletal bone loss may be developed for jaw bone indications in dentistry. Alveolar bone responsible for housing dentition share common bone remodeling mechanisms with skeletal bone. Manipulating alveolar bone turnover can be used as a strategy to treat diseases such as periodontitis, where large bone defects from disease are a surgical treatment challenge and to control tooth position in orthodontic treatment, where moving teeth through bone in the treatment goal. Developing such therapeutics for dentistry is a future line for research and therapy. Furthermore, it underscores the interprofessional relationship that is the future of healthcare.

Analysis of orthopedic surgery of patients with metastatic bone tumors and pathological fractures

Objective

This study was performed to determine the most common causes, locations, and treatments of metastasizing primary tumors through evaluation of patients with metastatic bone tumors who were admitted to our clinic.

Methods

In total, 96 patients with metastatic bone tumors who were admitted to our clinic from 2000 to 2016 were included in the study.

Results

The breast (30 patients, 31.3%) and lung (18 patients, 18.8%) were the most commonly metastasized primary organs. The femur was the most commonly metastasized bone.

Conclusions

Bone tumors in patients of advanced age are, unless otherwise proven, considered to be metastatic, and the development of specific diagnostic and treatment algorithms is needed. Clinicians should attempt to improve the general condition of patients with tumors exhibiting bone metastasis to increase the patients’ quality of life by providing early mobilization. Thus, appropriate patient selection and proper internal fixation are essential.

γδ T cells in cancer immunotherapy

γδ T cells are one of the three immune cell types that express antigen receptors. They contribute to lymphoid antitumor surveillance and bridge the gap between innate and adaptive immunity. γδ T cells have the capacity of secreting abundant cytokines and exerting potent cytotoxicity against a wide range of cancer cells. γδ T cells exhibit important roles in immune-surveillance and immune defense against tumors and have become attractive effector cells for cancer immunotherapy. γδ T cells mediate anti-tumor therapy mainly by secreting pro-apoptotic molecules and inflammatory cytokines, or through a TCR-dependent pathway. Recently, γδ T cells are making their way into clinical trials. Some clinical trials demonstrated that γδ T cell-based immunotherapy is well tolerated and efficient. Despite the advantages that could be exploited, there are obstacles have to be addressed for the development of γδ T cell immunotherapies. Future direction for immunotherapy using γδ T cells should focus on overcoming the side effects of γδ T cells and exploring better antigens that help stimulating γδ T cell expansion in vitro.

Stage-specific therapeutic strategies of medication-related osteonecrosis of the jaws: a systematic review and meta-analysis of the drug suspension protocol

OBJECTIVE

The most debated topic about medication-related osteonecrosis of the jaws (MRONJ) is its therapy, as there are no definitive guidelines. The aims of this systematic review were (a) to outline the best therapeutic approach according to the stage at diagnosis and (b) to perform a meta-analysis to assess whether the drug-holiday protocol may be or not an effective method in the management of MRONJ patients.

MATERIALS AND METHODS

The systematic review was performed following the PRISMA principles. Results were screened according to inclusion and exclusion criteria regarding staging before/after treatment, follow-up, and information provided by the authors. For statistical analysis, linear variables are reported as means and standard deviations, medians, and inter-quartile range (IQR); normality of data, according to the distribution of complete healing (primary outcome variable), was assessed with the Kolmogorov-Smirnov test. A p value < 0.05 was considered statistically significant for all tests.

RESULTS

Thirteen studies were selected out of 1480. None of them was case-controlled or randomized. Conservative approach showed good results at early stages, but heterogeneous result at advanced stages (100% stage 0, stage I range 81-97%, stage II range 63.6-100%, stage III 73%). Surgical approach showed heterogeneous results at all stages (stage I range 0-100%, stage II range 52-100%, stage III range 50-100%). Statistical analysis showed a significantly higher prevalence of completely healed sites in patients who followed the drug-holiday protocol.

CONCLUSIONS

The results suggest that the current stage-specific approach for MRONJ therapy is based on a sound clinical rationale. Conservative treatment appears to yield better outcomes at early stages, while further investigations are needed to elucidate the best protocols for the management of advanced stages. The drug-holiday protocol statistically promotes complete healing after oral surgery procedures but the application should be dictated by the condition of each patient.

CLINICAL RELEVANCE

At present, early MRONJ stages should be primarily treated by means of a conservative approach while more advanced stages must be carefully evaluated. Individual decisions should be made for every single case even with respect to the drug-holiday protocol.

Geranylgeranyl diphosphate synthase inhibition induces apoptosis that is dependent upon GGPP depletion, ERK phosphorylation and caspase activation

Bisphosphonates are diphosphate analogs that inhibit the intermediate enzymes of the mevalonate pathway. Here, we compared the effects of a farnesyl diphosphate synthase inhibitor, zoledronate, and a geranylgeranyl diphosphate synthase (GGDPS) inhibitor, digeranyl bisphosphonate (DGBP), on lymphocytic leukemia cell proliferation and apoptosis. Both zoledronate and DGBP inhibited proliferation with DGBP doing so more potently. DGBP was markedly less toxic than zoledronate toward the viability of healthy human peripheral blood mononuclear cells. Addition of GGPP, but not farnesyl diphosphate (FPP), prevented the anti-proliferative effects of DGBP. Both GGPP and FPP partially rescued the effects of zoledronate. Co-treatment with DGBP and zoledronate was antagonistic. To further assess the effects of the bisphosphonates, we analyzed annexin V and propidium iodide staining via flow cytometry and found that DGBP induced apoptosis more potently than zoledronate. Western blots show that DGBP treatment altered expression and membrane affinity of some but not all geranylgeranylated small GTPases, activated caspases and increased ERK phosphorylation. Importantly, the anti-proliferative effects of DGBP were blocked by treatment with a caspase inhibitor and by treatment with a MEK inhibitor. Together, our findings indicate that DGBP is a more potent and selective compound than zoledronate in inducing apoptosis mediated through pathways that include caspases and MEK/ERK. These findings support the further development of GGDPS inhibitors as anticancer therapeutics.

Role of intravenous dosage regimens of bisphosphonates in relation to other aetiological factors in the development of osteonecrosis of the jaws in patients with myeloma

The aim of this case-control study was to identify possible explanatory risk factors for the development of bisphosphonate-related osteonecrosis of the jaws (BRONJ) by estimating the effects of intravenous dosage regimens of bisphosphonates, coexisting diseases, and other drugs on 201 patients with multiple myeloma, with or without BRONJ. We compared sex, treatment with bisphosphonates, incidence of diabetes, and the taking of drugs such as corticosteroids and chemotherapy in patients who had BRONJ (n=44) and patients who did not (n=157). Among the bisphosphonates given intravenously zoledronic acid showed a stronger correlation with BRONJ than pamidronic acid. The risk of developing BRONJ increased dramatically at cumulative intravenous doses of more than 78 mg of zoledronic acid or 600 mg of pamidronic acid, which corresponds to treatment for 18 months or longer. Diabetes mellitus correlated significantly with the development of BRONJ (p=0.01) while there was no correlation with sex, simultaneous treatment with corticosteroids, or chemotherapy. In conclusion, treatment with zoledronic acid, high doses of pamidronic acid, and the coexistence of diabetes mellitus seem to be associated with the development of BRONJ.

Targeting bone metastases in prostate cancer: improving clinical outcome

Bone metastases develop in most patients with metastatic castration-resistant prostate cancer (mCRPC). They affect the structural integrity of bone, manifesting as pain and skeletal-related events (SREs), and are the primary cause of patient disability, reduced quality of life (QOL) and death. Understanding the pathophysiology of bone metastases resulted in the development of agents that improve clinical outcome, suggesting that managing both the systemic disease and associated bone events is important. Historically, the treatment of CRPC bone metastases with early radiopharmaceuticals and external beam radiation therapy was largely supportive; however, now, zoledronic acid and denosumab are integral to the therapeutic strategy for mCRPC. These agents substantially reduce skeletal morbidity and improve patient QOL. Radium-223 dichloride is the first bone-targeting agent to show improved survival and reduced pain and symptomatic skeletal events in patients with mCRPC without visceral disease. Five other systemic agents are currently approved for use in mCRPC based on their ability to improve survival. These include the cytotoxic drugs docetaxel and cabazitaxel, the hormone-based therapies, abiraterone and enzalutamide, and the immunotherapeutic vaccine sipuleucel-T. Abiraterone and enzalutamide are able to reduce SREs and improve survival in this setting. Novel agents targeting tumour and bone cells are under clinical development.

The correlation between lateral bowing angle of the femur and the location of atypical femur fractures

This study is the first to report the use of data on incomplete atypical femur fracture (AFF) to evaluate the curvature of femur and explore the relationship between lateral femoral bowing angle (FBA) and AAF location. In this study, we obtained 17 cases of incomplete AFF and calculated the accurate lateral FBA and location ratio of the incomplete fracture. Incomplete fracture location was defined as a percentage (length from lesion to greater trochanter tip/entire femur length %; greater trochanter tip: 0 %; femoral condyles: 100 %). A lateral FBA of 7° was set as the point of demarcation. Eleven femurs had a lateral FBA ≤ 7° (group 1), with a median lateral FBA of 4.75° (IQR 2.5-5.9°) and a median of incomplete AFF location at 25.2 % (IQR 23.4-30.1 %). Another six femurs had a FBA > 7° (group 2) with a median of 1.8° (IQR 10.2-14.3°) and a median location at 47.7 % (IQR 38.6-54.5 %). There was a significant statistical difference in location (p < 0.05) between the two groups. The rate of BP use was 87.5 % in group 1 which was higher than 60 % in group 2. There was some degree of positive correlation between the bowing angle and location in simple linear regression (r (2) = 0.549, p < 0.001, ß = 1.789). AAFs located in diaphysis were associated with large lateral FBA. On the other hand, AAFs located in subtrochanteric region were more commonly found in femurs with smaller lateral FBA. In conclusion, the degree of the FBA was associated with AFF location.

Atypical femoral fractures shortly after osteonecrosis of the jaw in a postmenopausal woman taking alendronate for osteoporosis

CONTEXT

Bisphosphonates effectively increase bone mineral density and reduce fracture risk in patients with osteoporosis, but there are concerns about osteonecrosis of the jaw (ONJ) and atypical femoral fractures (AFFs) in the long-term users. So far both complications have not been reported as occurring simultaneously in an osteoporotic individual on oral alendronate.

OBJECTIVE

The aim of this study was to report a postmenopausal woman presenting with concomitant ONJ and AFF on oral alendronate treatment. SUBJECT, MEASURES, AND RESULT: The patient was a 63-year-old woman with a history of rheumatoid arthritis for 30 years and diabetes for 3 years. Spinal compression fractures at levels L3 and L4 were documented, and she took alendronate 70 mg weekly for 7 years. She is the first case whose dental periapical imaging and pelvic radiography documented her ONJ and AFF, which developed subsequently within 6 months.

CONCLUSIONS

This case report supports the association of both ONJ and AFF with long-term oral bisphosphonate therapy.

The model organism Dictyostelium discoideum

Much of our knowledge of molecular cellular functions is based on studies with a few number of model organisms that were established during the last 50 years. The social amoeba Dictyostelium discoideum is one such model, and has been particularly useful for the study of cell motility, chemotaxis, phagocytosis, endocytic vesicle traffic, cell adhesion, pattern formation, caspase-independent cell death, and, more recently, autophagy and social evolution. As nonmammalian model of human diseases D. discoideum is a newcomer, yet it has proven to be a powerful genetic and cellular model for investigating host-pathogen interactions and microbial infections, for mitochondrial diseases, and for pharmacogenetic studies. The D. discoideum genome harbors several homologs of human genes responsible for a variety of diseases, -including Chediak-Higashi syndrome, lissencephaly, mucolipidosis, Huntington disease, IBMPFD, and Shwachman-Diamond syndrome. A few genes have already been studied, providing new insights on the mechanism of action of the encoded proteins and in some cases on the defect underlying the disease. The opportunities offered by the organism and its place among the nonmammalian models for human diseases will be discussed.

Is oral bisphosphonate-related osteonecrosis of the jaw an endemic condition?

Since the introduction of bisphosphonates to treat diseases that affect bone remodelling, there has been an increasing number of cases of bisphosphonate (BP)-related osteonecrosis of the jaw (BRONJ). Epidemiological data regarding BRONJ vary widely between studies, and a number of potential methodological biases have been detected. In some small preliminary studies, single nucleotide polymorphisms associated with an increased risk of BRONJ among cancer patients have been identified. However, genetic susceptibility to oral BP-related BRONJ has not previously been discussed. We suggest that epidemiological variability could be related to the existence of a susceptibility factor particularly prevalent in the population of a well-defined geographical region. To support our hypothesis we performed a search for published case series, only including those with at least 10 patients detected in a single city or a delimited geographical region; this showed that 55% of reports came from Mediterranean countries such as Italy, Israel, Spain and France. The finding does not appear to be conditioned by publication bias. Furthermore, conditions such as classic Kaposi sarcoma and beta-thalassaemia, though not exclusive to the Mediterranean region, also have a high prevalence in that area. We speculate that some of the patients included in the selected US and Australian series may be of Spanish or Italian descent. With an ageing population, the prevalence of osteoporosis will increase, and the number of cases of oral BP-related BRONJ may rise exponentially. Identification of risk groups with susceptibility to BRONJ will arise caution when prescribing BPs and will allow new preventive and therapeutic strategies to be developed.

Role of farnesoid X receptor (FXR) in the process of differentiation of bone marrow stromal cells into osteoblasts

Bone tissue contains bile acids which accumulate from serum and which can be released in large amounts in the bone microenvironment during bone resorption. However, the direct effects of bile acids on bone cells remain largely unexplored. Bile acids have been identified as physiological ligands of the farnesoid X receptor (FXR, NR1H4). In the present study, we have examined the effects of FXR activation/inhibition on the osteoblastic differentiation of human bone marrow stromal cells (BMSC). We first demonstrated the expression of FXR in BMSC and SaOS2 osteoblast-like cells, and observed that FXR activation by chenodeoxycholic acid (CDCA) or by farnesol (FOH) increases the activity of alkaline phosphatase and the calcification of the extracellular matrix. In addition, we observed that FXR agonists are able to stimulate the expression of osteoblast marker genes [bone sialoprotein (BSP), osteocalcin (OC), osteopontin (OPN) and alkaline phosphatase (ALP)] (FXR involvement validated by shRNA-induced gene silencing), as well as the DNA binding activity of the bone transcription factor RUNX2 (EMSA and ChIP assay). Importantly, we observed that nitrogen-containing bisphosphonates (BPs) inhibit the basal osteoblastic differentiation of BMSC, possibly through suppression of endogenous FOH production, independently of their effects on protein prenylation. Likewise, we found that the FXR antagonist guggulsterone (GGS) inhibits ALP activity, calcium deposition, DNA binding of RUNX2, and bone marker expression, indicating that GGS interferes with osteoblastic differentiation. Furthermore, GGS induced the appearance of lipid vesicles in BMSC and stimulated the expression of adipose tissue markers (peroxisome proliferator activated receptor-gamma (PPARγ), adipoQ, leptin and CCAAT/enhancer-binding protein-alpha (C/EBPα)). In conclusion, our data support a new role for FXR in the modulation of osteoblast/adipocyte balance: its activation stimulates RUNX2-mediated osteoblastic differentiation of BMSC, whereas its inhibition leads to an adipocyte-like phenotype.

A primer of bone metastases management in breast cancer patients

Bone is the most common site for distant spread of breast cancer. Following a diagnosis of metastatic bone disease, patients can suffer from significant morbidity because of pain and skeletal related events (SRES). Bisphosphonates are potent inhibitors of osteoclastic function and the mainstay of bone-directed therapy for bone metastases. The aims of bisphosphonates are to prevent and delay SRES, to reduce bone pain, and to improve quality of life. Bisphosphonate therapy appears to have revolutionized treatment of bone metastases, but bisphosphonate use has several limitations. Those limitations include the high cost of the agents and the need for return trips to the clinic for intravenous treatment. Moreover, many uncertainties surround bisphosphonate use-for example, the timing of bisphosphonate initiation, the choice of bisphosphonate to use, the optimal duration of treatment, and the appropriate means to identify patients who will and will not benefit. In addition, potentially serious adverse effects have been associated with bisphosphonate use-for example, renal toxicity, gastrointestinal side effects, and osteonecrosis of the jaw. The present review is intended as a primer for oncology specialists who treat patients with bone metastases secondary to breast cancer. It focuses on bisphosphonate treatment guidelines, the evidence for those guidelines, and a discussion of new therapeutic agents. It also discusses the use of biochemical markers of bone metabolism, which show promise for predicting the risk of a patient's developing a SRE and of benefiting from bisphosphonate treatment.

Novel approaches in the management of myeloma-related skeletal complications

Patients with multiple myeloma (MM) experience pathologic fractures, bone pain, hypercalcemia, neurologic symptoms, and renal insufficiency with substantial morbidity and mortality. Bisphosphonates have been used successfully for the management of MM-related bone disease. Increased incidence of osteonecrosis of the jaw has been observed in patients with cancer receiving bisphosphonate therapy. Recent advances in the pathobiology of MM-related bone disease and other cancer-related bone metastases have led to the identification of novel therapeutic targets, such as receptor activator of nuclear factor-kappaB (RANK); its ligand (RANKL); and a decoy receptor, osteoprotegerin, for the development of potential targeted agents. Initials studies have demonstrated that targeting RANK/ RANKL signaling with the fully human monoclonal antibody denosumab prevented skeletal complications in patients with MM and other cancers with bone metastases. Ongoing studies evaluating the clinical utility of denosumab in cancer- related bone destruction have been discussed. In addition, several potential targets, such as macrophage inflammatory protein-1alpha, chemokine receptors 1 and 5, interleukin-3, and Wnt signaling, are b riefly described.

Effect of zoledronic acid and amputation on bone invasion and lung metastasis of canine osteosarcoma in nude mice

Osteosarcoma (OSA) is an aggressive, highly metastatic and lytic primary bone neoplasm commonly affecting the appendicular skeleton of dogs and children. Current treatment options include amputation of the afflicted limb, limb-sparing procedures, or palliative radiation with or without adjunct chemotherapy. Therapies that inhibit bone resorption, such as the bisphosphonates, may be an effective palliative therapy by limiting the local progression of OSA in those patients that are not viable candidates for amputation. We have developed a mouse model of canine skeletal OSA following intratibial inoculation of OSCA40 cells that spontaneously metastasized to the lungs. We demonstrated that therapy with a nitrogen-containing bisphosphonate, zoledronic acid (Zol), reduced OSA-induced bone lysis; however, Zol monotherapy or in combination with amputation was not effective at inhibiting pulmonary metastasis. While not reaching statistical significance, amputation of the tumor-bearing limb reduced the average incidence of lung metastases; however, this effect was nullified when Zol was added to the treatment protocol. In untreated mice, the magnitude of proximal tibial lysis was significantly correlated with the incidence of metastasis. The data support amputation alone for the management of appendicular OSA rather than combining amputation with Zol. However, in patients that are not viable candidates for amputation, Zol may be a useful palliative therapy for OSA by reducing the magnitude of lysis and therefore bone pain, despite the risk of increased pulmonary metastasis.

Risk factors contributing to the development of hypocalcemia after zoledronic acid administration in patients with bone metastases of solid tumor

Zoledronic acid (ZDA) is commonly prescribed to treat and prevent skeletal complications in patients with multiple myeloma or bone metastases. Although hypocalcemia often develops by ZDA, there is little information about the risk factors for hypocalcemia mediated by ZDA. This study was conducted to assess the risk of ZDA-mediated hypocalcemia. We retrospectively reviewed the records of patients receiving ZDA in Mie University Hospital. The subjects were divided into two groups on the basis of whether hypocalcemia developed (19 patients) or not (30 patients). We compared patients' baseline characteristics between the two groups. The patients with hypocalcemia had lower albumin-adjusted serum calcium concentrations (median 9.2 mg/dl) before ZDA administration than the patients without hypocalcemia (median 9.8 mg/dl) (p< 0.01). Multivariate analysis revealed that an adjusted serum calcium concentration lower than 9.5 mg/dl before ZDA administration was an independent risk factor significantly contributing to the development of hypocalcemia (odds ratio 22.0, p< 0.01). Furthermore, the patients receiving corticosteroid had increased risk of ZDA mediated hypocalcemia (odds ratio 11.9, p<0.05). On the other hand, the patients with prostate cancer had a reduced risk for hypocalcemia after ZDA administration (odds ratio 0.06, p<0.05). In conclusion, a lower serum calcium concentration and co-administration of corticosteroid increased the risk of hypocalcemia after ZDA administration, while patients with prostate cancer might have a small risk of this incidence. These findings should provide useful information regarding the monitoring of serum calcium concentration in cancer patients receiving ZDA.

Anabolic and antiresorptive drugs improve trabecular microarchitecture and reduce fracture risk following radiation therapy

Many patients with symptomatic bone metastases receive radiation therapy, even though radiation is known to have potential adverse effects on bone. We hypothesized that the concurrent use of a bisphosphonate drug (zoledronic acid, ZA) or a combination of ZA plus an anabolic agent (parathyroid hormone, PTH) would lead to improvements in the microarchitecture and mechanical properties of irradiated bone. Human breast cancer cells were injected into the distal femur of 56 female nude mice, which were then divided into four groups: no treatment (0 Gy), radiation administered 4 weeks postinjection (20 Gy), radiation plus ZA (12.5 microg/kg weekly from weeks 4 to 12) (20 Gy + ZA), and radiation followed by ZA (25 microg/kg weekly from weeks 4 to 8) and PTH(1-34) (100 microg microg/kg daily from weeks 8 to 12) (20 Gy + ZA + PTH). Left limbs served as normal control bones. Bone loss over the 12-week study was tracked with serial radiography and bone densitometry. At the end of the study, micro-computed tomography and mechanical testing were used to quantify bone microarchitecture and bone strength. Radiation alone failed to prevent tumor-induced decreases in bone mineral density (BMD), trabecular bone volume, and bone strength. Treatment with 20 Gy + ZA or 20 Gy + ZA + PTH as adjuncts to radiation was effective at preserving trabecular bone architecture and bone strength at normal levels. ZA reduced the risk of mechanical fragility following irradiation of a lytic bone lesion. Supplemental use of PTH did not result in further increases in bone strength but was associated with significant increases in BMD and bone mass, suggesting that it may be beneficial in enhancing bone architecture following radiation therapy.

A promising approach for treatment of tumor-induced bone diseases: utilizing bisphosphonate derivatives of nucleoside antimetabolites

Despite palliative treatments, tumor-induced bone disease (TIBD) remains highly debilitating for many cancer patients and progression typically results in death within two years. Therefore, more effective therapies with enhanced anti-resorptive and cytotoxic characteristics are needed. We developed bisphosphonate-chemotherapeutic conjugates designed to bind bone and hydrolyze, releasing both compounds, thereby targeting both osteoclasts and tumor cells. This study examined the effects of our lead compound, MBC-11 (the anhydride formed between arabinocytidine (AraC)-5'-phosphate and etidronate), on bone tumor burden, bone volume, femur bone mineral density (BMD), and overall survival using two distinct mouse models of TIBD, the 4T1/luc breast cancer and the KAS-6/1-MIP1alpha multiple myeloma models. In mice orthotopically inoculated with 4T1/luc mouse mammary cells, MBC-11 (0.04 microg/day; s.c.) reduced the incidence of bone metastases to 40% (4/10), compared to 90% (9/10; p=0.057) and 100% (5/5; p=0.04) of PBS- or similarly-dosed, zoledronate-treated mice, respectively. MBC-11 also significantly decreased bone tumor burden compared to PBS- or zoledronate-treated mice (p=0.021, p=0.017, respectively). MBC-11 and zoledronate (0.04 microg/day) significantly increased bone volume by two- and four-fold, respectively, compared to PBS-treated mice (p=0.005, p<0.001, respectively). In mice systemically injected with human multiple myeloma KAS-6/1-MIP1alpha cells, 0.04 and 4.0 microg/day MBC-11 improved femur BMD by 13% and 16%, respectively, compared to PBS (p=0.025, p=0.017, respectively) at 10 weeks post-tumor cell injection and increased mean survival to 95 days compared to 77 days in mice treated with PBS (p=0.047). Similar doses of zoledronate also improved femur BMD (p< or =0.01 vs PBS) and increased mean survival to 86 days, but this was not significantly different than in PBS-treated mice (p=0.53). These results demonstrate that MBC-11 decreases bone tumor burden, maintains bone structure, and may increase overall survival, warranting further investigation as a treatment for TIBD.

Is there a role for ibandronate in the treatment of prostate cancer patients with bony metastases?

PURPOSE

Zoledronic acid is widely accepted as the treatment of choice for a number of cancers which metastasise to bone and is the only bisphosphonate licensed for the treatment of prostate cancer. However, drug related nephrotoxicity, although rare, does pose a significant complication when using zoledronic acid. Prostate cancer patients are generally older than 65 years of age and already exhibit some form of impaired renal function. Thus, for prostate cancer patients who are unable to tolerate zoledronic acid there is a need for an alternative bisphosphonate. One possibility could be ibandronate which is also a potent third generation, nitrogen-containing bisphosphonate and is an attractive choice for some patients due to the fact it is available in both intravenous and oral preparations.

METHODS

This article reviews the current published literature regarding the use of ibandronate in the treatment of metastatic prostate cancer.

RESULTS

Preliminary data emerging from small Phase II studies suggests ibandronate may provide a therapeutic alternative for the treatment of metastatic prostate cancer when zoledronic acid is deemed unsuitable.

CONCLUSION

Further in vivo research with ibandronate in prostate cancer is urgently needed in order to elucidate whether this bisphosphonate may play a role in the treatment and palliative management of metastatic prostate cancer.

A single pretreatment by zoledronic acid converts metastases from osteolytic to osteoblastic in the rat

Bone metastases are severe complications of cancers associated with increased morbidity, pain, risk fracture, and reduced life span for patients. Bisphosphonates emerged as a relief treatment in bone metastases. A single dose of zoledronic acid (78 microg/kg) was injected into six Copenhagen rats 4 days before receiving an intraosseous inoculation of metastatic anaplastic tumor of lymph node and lung cell (MLL) prostate cancer cells. Rat femurs were analyzed for changes by microCT and histomorphometry; trabecular volume, trabecular characteristics, osteoid parameters, osteoblastic surfaces, and osteoclast number were measured. Values were compared to a group of SHAM animals, a group of SHAM animals having received zoledronic acid and animals inoculated with MLL cells. All rats were euthanized after 1 month. MLL cells induced osteolysis in the metaphysis with extension of the tumor to soft tissues through cortical perforations. Zoledronic acid induced a marked osteosclerosis in the primary spongiosa in both SHAM and rats inoculated with MLL. Osteosclerosis was obtained in the secondary spongiosa of MLL rats. The bisphosphonate preserved cortical integrity in all animals, and no extension to soft tissues was observed in most animals. The number of osteoclasts was elevated, indicating that there was no apoptosis of osteoclasts but they became inactive. Osteosclerosis was associated with increased osteoblastic surfaces. A single zoledronic acid injection turned osteolytic metastases into osteosclerotic and preserved cortical integrity.

Osteoclast-targeting small molecules for the treatment of neoplastic bone metastases

Osteoclasts are highly specialized cells that resorb bone, and their abnormal activity is implicated in a variety of human bone diseases. In neoplastic bone metastasis, the bone destruction caused by osteoclasts is not only associated with the formation and progression of metastatic lesions, but also could contribute to frequent complications such as severe pain and pathological fractures, which greatly diminish the quality of life of patients. Bisphosphonates, potent antiresorptive drugs, have been shown to have efficacy for treating bone metastases in many types of cancer, and the development of various molecularly targeted agents is currently proceeding. Thus, inhibition of osteoclast function is now established as an important treatment strategy for bony metastases. This review focuses on promising small molecules that disrupt osteoclast function and introduces our chemical/biological approach for identifying osteoclast-targeting small molecular inhibitors.

Treatment Options for Breast Cancer and Bone Metastases

The most common destination for breast cancer metastases is bone. If bone metastases are detected, treatment algorithms should include the continuation of cytoreductive therapy with the addition of treatment to counter skeletal-related events, including bone pain. The range of current treatment options includes bisphosphonates, surgical intervention to improve structural integrity and palliative focal radiotherapy. This article focuses on the role of bisphosphonate therapy in metastatic breast cancer. Bisphosphonate therapy significantly reduces the impact of skeletal-related events, reduces bone pain and increases patient quality of life. Our current understanding is that bisphosphonates may also disrupt the metastatic process and reduce the development of bone lesions. Ultimately, this may lead to further expansion of bisphosphonate-based therapy in the future.

Osteonecrosis of the jaw complicating bisphosphonate treatment for bone disease in multiple myeloma: an overview with recommendations for prevention and treatment

Osteonecrosis of the Jaw (ONJ) is a recently recognised and potentially highly morbid complication of bisphosphonate therapy in the setting of metastatic malignancy, including myeloma. Members of the Medical and Scientific Advisory Group of the Myeloma Foundation of Australia formulated guidelines for the management of bisphosphonates around the issue of ONJ, based on the best available evidence in June 2008. Prior to commencement of therapy, patients should have an oral health assessment and be educated about the risks of ONJ. Dental assessment should occur 6 monthly during therapy. If tooth extraction is required, sufficient time should be allowed for complete healing to occur prior to commencement of bisphosphonate. As the risk of ONJ increases with duration of bisphosphonate therapy, we recommend annual assessment of dose with modification to 3 monthly i.v. therapy or to oral therapy with clodronate for those with all but the highest risk of skeletal-related event. Established ONJ should be managed conservatively; a bisphosphonate "drug holiday" is usually indicated and invasive surgery should generally be avoided. These recommendations will assist with clinical decision making for myeloma patients who are at risk of bisphosphonate-associated ONJ.

Intravenous ibandronate rapidly reduces pain, neurochemical indices of central sensitization, tumor burden, and skeletal destruction in a mouse model of bone cancer

Over half of all chronic cancer pain arises from metastases to bone and bone cancer pain is one of the most difficult of all persistent pain states to fully control. Currently, bone pain is treated primarily by opioid-based therapies, which are frequently accompanied by significant unwanted side effects. In an effort to develop nonopioid-based therapies that could rapidly attenuate tumor-induced bone pain, we examined the effect of intravenous administration of the bisphosphonate, ibandronate, in a mouse model of bone cancer pain. Following injection and confinement of green fluorescent protein-transfected murine osteolytic 2472 sarcoma cells into the marrow space of the femur of male C3H/HeJ mice, ibandronate was administered either as a single dose (300 microg/kg), at Day 7 post-tumor injection, when tumor-induced bone destruction and pain were first evident, or in three consecutive doses (100 microg/kg/day) at Days 7, 8, and 9 post-tumor injection. Intravenous ibandronate administered once or in three consecutive doses reduced ongoing and movement-evoked bone cancer pain-related behaviors, neurochemical markers of central sensitization, tumor burden, and tumor-induced bone destruction. These results support limited clinical trials that suggest the potential of ibandronate to rapidly attenuate bone pain and illuminate the mechanisms that may be responsible for limiting pain and disease progression.

Significance and impact of bisphosphonate-induced acute phase responses

BACKGROUND

Bisphosphonates are synthetic analogs of inorganic pyrophosphates with high avidity for bone, where they bind to hydroxyapatite crystals. Bisphosphonates are effective in decreasing bone resorption, the incidence of skeletal-related events, and pain from bone metastases. These agents have recently become incorporated into the treatment regimen of patients with osteolytic and osteoblastic metastatic bone disease. Although relatively well tolerated, the initial dose(s) of intravenous aminobisphosphonates can be associated with an acute phase response, a nonspecific physiologic reaction associated with increased levels of inflammatory cytokines, fever, and flu like symptoms including fatigue, nausea, and myalgia.

OBJECTIVE

The purpose of this article is to provide an updated review of the literature in this field.

DATA SOURCE

A search of PubMed was performed using the key terms bisphosphonate, acute phase response, and cancer, and limited to publications in English. The published literature on acute phase response with bisphosphonate therapy was reviewed.

RESULTS AND CONCLUSIONS

Approximately 40% of patients receiving aminobisphosphonates experience an acute phase response, which generally occurs only on first exposure to the drug and typically last <72 h. Not all bisphosphonates induce acute phase responses to the same extent. This article reviews acute phase response in patients with metastatic bone disease treated with aminobisphosphonates.

Risk factors for symptomatic hypocalcaemia complicating treatment with zoledronic acid

BACKGROUND

The bisphosphonate zoledronic acid is commonly prescribed to prevent skeletal complications in patients with multiple myeloma or metastatic cancer. Although symptomatic hypocalcaemia is a potential risk of treatment, it has been thought to be uncommon.

AIMS

After seeing several episodes of symptomatic hypocalcaemia following zoledronic acid administration, we undertook a review to determine the incidence of this complication in our population and to attempt to identify risk factors.

METHODS

We reviewed the records of all patients receiving zoledronic acid in two teaching hospitals over a 2-year period. Findings collected included the indication for treatment, whether dosing was adjusted for creatinine clearance, coadministered medications, serum chemistries and clinical course.

RESULTS

Of 120 patients who received a total of 546 zoledronic acid infusions, hypocalcaemia developed related to 55 infusions (10%) in 42 patients (35%). Symptomatic hypocalcaemia requiring i.v. supplementation occurred in 10 patients (8%), in spite of appropriate dose adjustment for creatinine clearance and despite prophylactic administration of oral calcium and vitamin D. More patients who became hypocalcaemic developed impairment of creatinine clearance during zoledronic acid treatment than in the group that remained normocalcaemic. Hypomagnesaemia was found in all patients who developed hypocalcaemia who had serum magnesium measured.

CONCLUSIONS

Hypocalcaemia was common in our patient group following zoledronic acid treatment. Because of the prolonged elimination half-life of this agent (146 h), renal impairment occurring during a number of days after administration may increase risk. Hypomagnesaemia may further increase risk by blunting compensatory increase in parathyroid hormone secretion.

Palliative care in orthopaedic surgical oncology

Hundreds of thousands of Americans are affected every year by skeletal complications of oncologic disease. Recent developments in medical oncology, radiation oncology and radiology, particularly with respect to the use of bisphosphonate medication and radiofrequency techniques, have served to greatly lessen the morbidity associated with metastatic skeletal disease. Similarly, there has been significant advancement in the field of orthopaedic oncology in the areas of internal fixation, endoprosthetic implant design, and minimally invasive kyphoplasty technology. Given the palliative intent of intervention in this patient population, the goal of treatment of skeletal metastases must be optimization of limb function and ultimately, quality of life.

Management of cancer treatment-induced bone loss in early breast and prostate cancer -- a consensus paper of the Belgian Bone Club

Cancer treatment-induced bone loss (CTIBL) is one of the most important side effects of adjuvant antineoplastic treatment in hormone-dependent neoplasms. Chemotherapy, GnRH analogs and tamoxifen can induce marked bone loss in premenopausal women with early breast cancer. Aromatase inhibitors (AIs) are replacing tamoxifen as the preferred treatment for postmenopausal women. As a class effect, steroidal (exemestane) and non-steroidal (anastrozole and letrozole) AIs increase bone turnover and cause bone loss (4%-5% over 2 years). When compared to tamoxifen, the risk of getting a clinical fracture under AI treatment is increased by 35%-50%. In patients with prostate cancer, androgen deprivation therapy (ADT) increases bone turnover, reduces bone mass (4%-5% per year) and increases the fracture rate depending on the duration of therapy. Zoledronic acid can prevent accelerated bone loss induced by goserelin in premenopausal women, by letrozole in postmenopausal women and by ADT in men. More limited data indicate that weekly alendronate or risedronate could also be effective for preventing CTIBL. Initiation of therapy early, prior to the occurrence of severe osteoporosis, rather than after, may be more effective. Bisphosphonate treatment should be considered in osteoporotic but also in osteopenic patients if other risk factor(s) for fractures are present.

Multiple myeloma/hypercalcemia

Multiple myeloma, a cancer of plasma cells, is associated with excessive tumor-induced, osteoclast-mediated bone destruction. Hypercalcemia remains the most frequent metabolic complication of myeloma in patients, and excessive osteolysis plays a major contributory role in its pathogenesis. The clinical presentation of hypercalcemia in patients varies depending on the level of ionized calcium; it can be life threatening, as in the case of hypercalcemic crisis, requiring immediate medical treatment to prevent death. During the past few years there have been exciting developments in our understanding of the pathogenesis of myeloma bone disease; in particular, key mediators of the osteoclastic bone resorption in myeloma have been identified, including receptor activator of nuclear factor-κB ligand (RANKL) and macrophage inflammatory protein-1α. There is also increasing evidence that Dickkopf 1, which has been shown to be over-expressed in myeloma patients, is also a potent stimulator of osteoclast formation and activity. Importantly, the available data suggest that RANKL is the final common mediator of osteoclastic bone resorption, irrespective of the upstream initiator molecule. This brief review presents an overview of the roles played by these mediators in inducing osteolysis in myeloma bone disease, and it discusses targeting RANKL as a potential new treatment strategy in myeloma bone disease and myeloma-associated hypercalcemia.

The use of bisphosphonates in cancer patients

Skeletal-related events resulting from bone metastases or osteoporosis can significantly contribute to morbidity and mortality in cancer patients. Expert opinion on the effectiveness of bisphosphonates in this setting is evolving. Here we review current evidence on the risks and benefits of bisphosphonate therapy for a wide variety of cancers, as well as clinical management of its adverse effects. A MEDLINE search of English-language literature (1966 through May 2006) was conducted using the terms bisphosphonate, cancer, multiple myeloma, malignancy, and randomized controlled clinical studies. Studies were selected based on clinical pertinence, with an emphasis on phase III clinical trials. We reviewed bibliographies for other relevant articles. Accumulating evidence reveals that bisphosphonate therapy has a significant effect in preventing skeletal complications in multiple myeloma, breast cancers, and prostate cancer, and in reducing skeletal complications in other metastatic bone malignancies. Emerging data indicate that bisphosphonates are useful for preventing bone loss resulting from cancer or its therapy. The efficacy of bisphosphonates for early-stage breast cancers remains controversial. Significant risks of bisphosphonate therapy include nephrotoxicity, electrolyte abnormalities, and osteonecrosis of the jaw. Bisphosphonate therapy has a clear role in the management of skeletal metastases associated with a variety of cancers. However, significant side effects require ongoing monitoring and treatment.