Toward New Horizons: The Future of Bisphosphonate Therapy

Drug-repositioning screening identified fludarabine and risedronic acid as potential therapeutic compounds for malignant pleural mesothelioma

Objectives Malignant pleural mesothelioma (MPM) is an occupational disease mainly due to asbestos exposure. Effective therapies for MPM are lacking, making this tumour type a fatal disease. Materials and Methods In order to meet this need and in view of a future "drug repositioning" approach, here we screened five MPM (Mero-14, Mero-25, IST-Mes2, NCI-H28 and MSTO-211H) and one SV40-immortalized mesothelial cell line (MeT-5A) as a non-malignant model, with a library of 1170 FDA-approved drugs. Results Among several potential compounds, we found that fludarabine (F-araA) and, to a lesser extent, risedronic acid (RIS) were cytotoxic in MPM cells, in comparison to the non-malignant Met-5A cells. In particular, F-araA reduced the proliferation and the colony formation ability of the MPM malignant cells, in comparison to the non-malignant control cells, as demonstrated by proliferation and colony formation assays, in addition to measurement of the phospho-ERK/total-ERK ratio. We have shown that the response to F-araA was not dependent upon the expression of DCK and NT5E enzymes, nor upon their functional polymorphisms (rs11544786 and rs2295890, respectively). Conclusion This drug repositioning screening approach has identified that F-araA could be therapeutically active against MPM cells, in addition to other tumour types, by inhibiting STAT1 expression and nucleic acids synthesis. Further experiments are required to fully investigate this.

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.

A prospective randomized controlled clinical trial of zoledronic acid for bone metastases

In this study, we assessed the safety, tolerability, and effectiveness of two therapeutic regimens relating to the frequency of zoledronic acid (ZOL) infusion. Sixty adult patients with bone metastases were randomly assigned to two study groups. The first group (group A) received 4 mg ZOL every two weeks, and the second group (group B) received 4 mg ZOL every four weeks. Assessment measures included C-telopeptide (CTX) rate, the Greek Brief Pain Inventory (GBPI), the linear analogue scale assessment (LASA) of quality of life, and biochemical markers. Assessments were made at weeks 12, 24, 36, and 48. Clinical endpoints included effective decrease in bone resorption markers, pain relief, and improvement of mobility status. The follow-up period was 48 weeks. No statistically significant differences between groups A and B were found in overall profile of biochemical markers, Eastern Cooperative Oncology Group (ECOG) performance status, and GBPI score at the end of the follow-up period. Assessment of bone metastases revealed a slight difference between the two groups, however this difference was not statistically significant. These findings indicate that administering zoledronic acid at four rather that two weeks has no significant impact on overall outcome.

Alendronate Functionalized Mesoporous Bioactive Glass Nanospheres

In this work we synthesized mesoporous bioactive glass nanospheres (nMBG) with the aim to utilize them as substrates for loading one of the most potent amino-bisphosphonates, alendronate (AL). The results of the chemical and structural characterization show that the nMBG display a relatively high surface area (528 m²/g) and a mean pore volume of 0.63 cm³/g, both of which decrease on increasing alendronate content. It is possible to modulate the amount of AL loaded into the nanospheres up to a maximum value of about 17 wt %. In vitro tests were performed using a human osteosarcoma cell line (MG63) and a murine monocyte/macrophage cell line as osteoclast model (RAW 264.7). The results indicate that even the lower concentration of alendronate provokes decreased tumor cell viability, and that osteoclast activity exhibits an alendronate dose-dependent inhibition. The data suggest that nMBG can act as a suitable support for the local delivery of alendronate, and that the antiresorptive and antitumor properties of the functionalized mesoporous nanospheres can be modulated by varying the amount of alendronate loading.

Treatment options for older woman with early breast cancer

Breast cancer is the most common cancer in women and its incidence increases with age. Older women are not often offered optimal treatment compared with younger women for any particular stage. This is due to various reasons, including the lack of evidence for older women from well-conducted clinical trials. In this paper, the currently available evidences from clinical trials are reviewed and the various treatment options for older women with early breast cancer are discussed.

Necrotic actions of nitrogen-containing bisphosphonates and their inhibition by clodronate, a non-nitrogen-containing bisphosphonate in mice: potential for utilization of clodronate as a combination drug with a nitrogen-containing bisphosphonate

Nitrogen-containing bisphosphonates (NBPs) exhibit powerful anti-bone-resorptive effects (ABREs) via inhibition of farnesyl pyrophosphate synthase during cholesterol biosynthesis. Clinical applications have disclosed an unexpected side effect, namely osteonecrosis of jaw bones, and although thousands of cases have been documented in the last few years the mechanism remains unclear. Since NBPs accumulate in bone-hydroxyapatite, more jaw bone osteonecrosis cases may come to light if NBPs continue to be used as they are being used now. We have previously reported that in mice, systemic (intraperitoneal) injection of clodronate (a non-NBP) prevents the inflammatory effects of NBPs. Here, we examined in mice the local necrotic actions of various NBPs and the anti-necrotic effects of clodronate. A single subcutaneous injection of an NBP into the ear pinna induced necrosis at the injection site (relative potencies of necrotic actions of NBPs: zoledronate >> pamidronate > or = alendronate > risedronate), while non-NBPs lacked this effect. Clodronate, when injected together with an NBP, reduced or prevented the necrosis induced by that NBP, but not its ABRE. Clodronate reduced the amount of each NBP retained within tissues. These results, together with those of previous studies, suggest that (i) clodronate inhibits the inflammatory and necrotic actions of NBPs by inhibiting their incorporation into cells related to inflammation and/or necrosis, (ii) clodronate could be useful as a combination drug with NBPs for preventing their necrotic actions while retaining their ABREs and (iii) clodronate could also be useful as a substitution drug for NBPs in patients at risk of osteonecrosis of jaw bones.

Mouse macrophages primed with alendronate down-regulate monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha) production in response to Toll-like receptor (TLR) 2 and TLR4 agonist via Smad3 activation

Alendronate is one of the nitrogen-containing bisphosphonates (NBPs) used as anti-bone resorptive drugs. However, NBPs have inflammatory side effects including osteomyelitis and osteonecrosis of the jaw. In the present study, we examined the effects of alendronate on chemokine production by the macrophage-like cell line, J774.1, when incubated with Pam(3)CSK(4) (a Toll-like receptor (TLR) 2 agonist) and Lipid A (a TLR4 agonist). Pretreatment of J774.1 cells with alendronate decreased the production of TLR ligand-induced monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha) but did not influence nuclear factor-kappaB (NF-kappaB) activation. While this agent induced caspase-8 activation, a caspase-8 inhibitor did not affect the decrease in MCP-1 production by alendronate and TLR ligands. Thus, the alendronate-mediated decrease in chemokine production was independent of NF-kappaB and caspase-8 activation. Although transforming growth factor-beta1 (TGF-beta1) is known to inhibit chemokine production by various cell types via Smad3 activation, pretreatment with alendronate did not increase TGF-beta1 production by J774.1 cells incubated in the presence or absence of TLR ligands. However, alendronate directly activated Smad3. These results suggest that by down-regulating MCP-1 and MIP-1alpha production via Smad3, long-term use of alendronate might inhibit normal activation and migration of osteoclasts and cause osteonecrosis.

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.

Alendronate augments interleukin-1beta release from macrophages infected with periodontal pathogenic bacteria through activation of caspase-1

Nitrogen-containing bisphosphonates (NBPs) are anti-bone-resorptive drugs with inflammatory side effects that include osteomyelitis and osteonecrosis of the jaw. Oral bacteria have been considered to be a trigger for these NBP-associated jaw bone diseases. The present study examined the effects of alendronate (a typical NBP) and clodronate (a non-NBP) on the production of proinflammatory cytokines by macrophages infected with Porphyromonas gingivalis and Tannerella forsythia, which are important pathogens of periodontal diseases. Pretreatment with alendronate augmented IL-1beta, but not TNFalpha, production by macrophages infected with P. gingivalis or T. forsythia. This augmentation of IL-1beta production was inhibited by clodronate. Furthermore, caspase-1, a promoter of IL-1beta production, was activated by treatment with alendronate, and caspase-1 inhibitor reduced the production of IL-1beta induced by alendronate and P. gingivalis. These results suggest that NBPs augment periodontal pathogenic bacteria-induced IL-1beta release via caspase-1 activation, and this phenomenon may contribute to the development of NBP-associated inflammatory side effects including jaw osteomyelitis. Co-treatment with clodronate may prevent and/or reduce these inflammatory effects induced by NBPs.

Cancer treatment-induced bone loss: pathophysiology and clinical perspectives

Hormone-ablative therapies for breast or prostate cancer can cause marked and rapid reductions in circulating estrogen or testosterone levels, resulting in significant effects on bone metabolism and cancer treatment-induced bone loss (CTIBL). Most patients with cancer are over the age of 65 and are already at risk for osteoporosis. Thus, accelerated bone loss from CTIBL is especially concerning in this population. Although there are currently no approved therapies for the treatment or prevention of CTIBL, oral bisphosphonates have been used in settings other than oncology to treat bone loss. New-generation i.v. bisphosphonates have demonstrated promising activity in preventing CTIBL in patients receiving hormonal therapy for breast or prostate cancer. In particular, zoledronic acid not only prevents CTIBL in both breast and prostate cancer patients but also increases bone mineral density above baseline. Such agents have the potential to delay or prevent CTIBL in patients receiving hormonal therapies.

Treatment delay of bone tumours, compilation of a sociodemographic risk profile: a retrospective study

BACKGROUND

Bone tumours are comparatively rare tumours and delays in diagnosis and treatment are common. The purpose of this study was to analyse sociodemographic risk factors for bone tumour patients in order to identify those at risk of prolonged patients delay (time span from first symptoms to consultation), professional delay (from consultation to treatment) or symptom interval (from first symptoms to treatment). Understanding these relationships might enable us to shorten time to diagnosis and therapy.

METHODS

We carried out a retrospective analysis of 265 patients with bone tumours documenting sociodemographic factors, patient delay, professional delay and symptom interval. A multivariate explorative Cox model was performed for each delay.

RESULTS

Female gender was associated with a prolonged patient delay. Age under 30 years and rural living predisposes to a prolonged professional delay and symptom interval.

CONCLUSION

Early diagnosis and prompt treatment are required for successful management of most bone tumour patients. We succeeded in identifying the histology independent risk factors of age under 30 years and rural habitation for treatment delay in bone tumour patients. Knowing about the existence of these risk groups age under 30 years and female gender could help the physician to diagnose bone tumours earlier. The causes for the treatment delays of patients living in a rural area have to be investigated further. If the delay initiates in the lower education of rural general physicians, further training about bone tumours might advance early detection. Hence the outcome of patients with bone tumours could be improved.

Ligand-modified aminobisphosphonate for linking proteins to hydroxyapatite and bone surface

An increase in bone resorption is one of the main symptoms of osteoporosis, a disease that affects more and more individuals every day. Bisphosphonates are known to inhibit bone resorption and thus are being used as a treatment for osteoporosis. Aminobisphosphonates present a functionality that can be easily used for conjugation to other molecules, such as peptides, proteins, and ligands for protein recognition. In this study, an aminobisphosphonate conjugated with biotin was used as a model linker for protein attachment to bone. With this system, the interaction of biotinylated aminobisphosphonate with hydroxyapatite, a major mineral component of bone, was investigated. Quantification of the binding of aminobisphosphonate to hydroxyapatite was performed using a fluorescently labeled antibody for biotin. Additionally, the interaction of the biotinylated aminobisphosphonate with multiple treatments of cortical bone from the midshaft of a cow femur was studied. It was demonstrated that modified aminobisphosphonate reagents can bind hydroxyapatite and bone at high levels, while the biotin functionality is free to be recognized by the fluorescently labeled antibiotin antibody, suggesting that modified aminobisphosphonates could be used to link other peptides or proteins to the bone surface.

New developments of aminobisphosphonates: the double face of Janus

BACKGROUND

Bisphosphonate (BP) therapy has become a standard of therapy for patients with malignant bone disease. In vivo preclinical and preliminary clinical data indicate that BPs may prevent cancer treatment-induced bone loss and the onset of malignant bone disease in patients with early-stage cancer.

DESIGN

This review will describe the preclinical evidences of action of BPs on osteoclasts and tumor cells. In addition, the effects of principal BPs on skeletal disease progression in patients with breast cancer, prostate cancer, non-small-cell lung cancer and other cancers will be reported. The preliminary clinical data from retrospective trials on the effect of zoledronic acid (ZA) on survival will be described and the ongoing adjuvant phase III trial will be analyzed.

CONCLUSIONS

This review will describe the preliminary clinical evidences from prospective studies on the effect of ZA treatment on the prevention of bone metastasis.

Zoledronic acid in the management of metastatic bone disease

Bisphosphonate therapy has become a standard of therapy for patients with malignant bone disease. Moreover, in vivo preclinical and preliminary clinical data suggest that bisphosphonates may prevent cancer treatment-induced bone loss and the onset of malignant bone disease in patients with early-stage cancer. This comprehensive review critically reports the several preclinical evidences of action of bisphosphonates on osteoclasts, lymphocytes and tumour cells. In addition, all the clinical trials evaluating the effects of principal bisphosphonates on skeletal disease progression in patients with breast cancer, prostate cancer, non-small cell lung cancer and other cancers have been reported. Of the available bisphosphonates, intravenous zoledronic acid has demonstrated the broadest clinical activity and is actually approved for the treatment of bone metastases from any solid tumour in many countries. Renal safety is an important consideration for oncologists who are treating patients with bisphosphonates. This issue and the other topics relating to the safety of bisphosphonates are discussed in this review.

International society of geriatric oncology (SIOG) clinical practice recommendations for the use of bisphosphonates in elderly patients

A society of geriatric oncology (SIOG) task force reviewed information from the literature (in PubMed) on bisphosphonates in elderly patients with bone metastases until December 2005. Additional pertinent data were obtained from the manufacturers. Bisphosphonates are recommended in the elderly with bone metastases to prevent skeletal-related events. Intravenous formulations are preferred for the treatment of hypercalcaemia. It has been recognised that zoledronic acid, ibandronate and pamidronate can effectively contribute in relieving metastatic bone pain. Creatinine clearance should be monitored in every patient, and a less renally toxic agent should be used where evidence of similar efficacy is available. The assessment and optimisation of hydration status is recommended. Due to the risk from osteonecrosis of the jaw, routine oral examination and treatment of dental problems by a dental team is recommended before bisphosphonates. Physicians should choose the most appropriate bisphosphonate. Safety precautions are particularly important in elderly patients. Further research is needed in this population.

Alendronate induces anti-migratory effects and inhibition of neutral phosphatases in UMR106 osteosarcoma cells

Bisphosphonates are nonhydrolysable pyrophosphate analogues that prevent bone loss in several types of cancer. However, the mechanisms of anticancer action of bisphosphonates are not completely known. We have previously shown that nitrogen-containing bisphosphonates directly inhibit alkaline phosphatase of UMR106 rat osteosarcoma cells. In this study, we evaluated the effects of alendronate on the migration of UMR106 osteosarcoma using a model of multicellular cell spheroids, as well as the alendronate effect on neutral phosphatases. Alendronate significantly inhibited the migration of osteoblasts in a dose-dependent manner (10(-6)-10(-4) M). This effect was also dependent on calcium availability. The spheroid morphology and distribution of actin fibers were also affected by alendronate treatment. Alendronate dose-dependently inhibited neutral phosphatase activity in cell-free osteoblastic extracts as well as in osteoblasts in culture. Our results show that alendronate inhibits cell migration through mechanisms dependent on calcium, and that seem to involve inhibition of phosphotyrosine-neutral-phosphatases and disassembly of actin stress fibers.

Efficient Total Syntheses and Structural Verification of Both Diospongins A and B via a Common δ-Lactone Intermediate

The total syntheses of the two aryl C-glycoside natural products diospongins A and B are described. The key reactions involved stereoselective reductions of the appropriate oxocarbenium cations that were derived from a common delta-lactone intermediate.

Statins may decrease skeletal-related events in breast cancer patients with bone metastases

Metastasis to the skeleton frequently occurs in breast carcinoma patients resulting in different skeletal-related events including pain, hypercalcemia, pathological fracture, and spinal cord or nerve root compression. Bisphosphonates are class of agents most frequently used to reduce skeletal-related events in patients with bone metastases by inhibiting osteoclast activity through inhibition of mevolanate pathway which is also important in cholesterol synthesis. Statins are cholesterol lowering agents and inhibit the same pathway. Therefore statins may also reduce skeletal-related events in breast cancer patients with bone metastases by inhibiting osteoclastic activity.

Anticancer effects of zoledronic acid against human osteosarcoma cells

Based on neoadjuvant chemotherapy, the prognosis of osteosarcoma patients has improved dramatically. However, due to therapy resistance in patient subgroups, the development of new treatment strategies is still of utmost importance. The aim of our study was to test the effects of the nitrogen-containing bisphosphonate zoledronic acid (ZOL) on osteosarcoma cell lines (N = 9). Exposure to ZOL at low micromolar concentrations induced a dose- and time-dependent block of DNA synthesis and cell cycle progression followed by microfilament breakdown and apoptosis induction. The ZOL-induced cell cycle accumulation in S phase was accompanied by significant changes in the expression of cyclins and cyclin-dependent kinase inhibitors with a prominent loss of cyclin E and D1. ZOL not only inhibited growth but also migration of osteosarcoma cells. The mevalonate pathway intermediary geranyl-geraniol (GGOH) but not farnesol (FOH) significantly inhibited the anticancer effects of ZOL against osteosarcoma cells. Correspondingly, ZOL sensitivity correlated with the blockade of protein geranylgeranylation indicated by unprenylated Rap1. Overexpression of even high levels of P-glycoprotein, as frequently present in therapy-resistant osteosarcomas, did not impair the anticancer activity of ZOL. Summarizing, our data suggest that ZOL, which selectively accumulates in the bone, represents a promising agent to improve osteosarcoma therapy.

Biphosphonates in Advanced Prostate and Renal Cell Cancer – Current Status and Potential Applications

OBJECTIVE

This review summarizes recent findings on the therapeutic benefits of biphosphonates in patients with advanced prostate or renal cell carcinoma (RCC). The role of biphosphonates in ADT-induced osteoporosis and delay of skeletal-related events (SREs) in metastatic bone disease is discussed. A brief overview on the proposed modes of action is given.

METHODS

Literature search of PubMed documented publications and abstracts from meetings.

RESULTS

Among the biphosphonates currently available, zoledronic acid is the only one known to be capable of delaying SREs in RCC and prostate cancer patients. Zoledronic acid counteracts cancer treatment-induced osteoporosis in men with prostate malignancies. The antitumor activity of biphosphonates found in vitro and in vivo is intriguing and has to be further assessed in clinical studies.

CONCLUSION

Due to its unique properties, zoledronic acid is a breakthrough in the management of metastatic bone disease in patients with advanced prostate cancer and RCC. It significantly improves the patients' quality of life, drastically prolongs time to first SRE, and showed a positive but not significant effect on survival.

Current management of treatment-induced bone loss in women with breast cancer treated in the United Kingdom

New therapeutic options in breast cancer have improved survival but consequently increase the relevance of late complications. Ovarian suppression/ablation and aromatase inhibitors (AI) in the adjuvant setting have improved outcome, but have clinically important adverse effects on bone health. However, investigation and management of cancer treatment-induced bone loss (CTIBL) is poorly defined with no national guidance. In 2004, a questionnaire was sent to over 500 breast surgeons and oncologists who treat breast cancer within the United Kingdom. The questionnaire evaluated access to bone densitometry and specialist expertise as well as attitudes to investigation of CTIBL and anticipated changes in the use of AI for postmenopausal early breast cancer. A total of 354 completed questionnaires were received, 47 from clinicians not currently treating breast cancer. Of the 307 evaluable questionnaires, 164 (53%) were from breast surgeons, 112 (36%) from clinical oncologists and 31 (10%) from medical oncologists. Although most respondents recognised that CTIBL was the responsibility of the treating breast team, investigations for CTIBL are limited even though most had adequate access to bone densitometry; 98 (32%) had not requested a DXA scan in the last 6 months and 224 (73%) had requested fewer than five scans. In all, 235 (76%) were not routinely investigating patients on AI for bone loss. A total of 277 (90%) felt that their practice would benefit from national guidelines to manage these patients, and the majority (59%) had little or no confidence in interpreting DXA results and advising on treatment. This questionnaire has highlighted clear deficiencies in management of CTIBL in early breast cancer. The development of national guidelines for the management of these patients and educational initiatives for breast teams are urgently required.

The use of bisphosphonates in palliative treatment of bone metastases in a terminally ill, oncological elderly population

According to the guidelines of WHO [WHO, 1999. Cancer Pain and Palliative Care Program. Cancer Pain Release, vol. 13], the term terminally ill patient refers to oncological patients whose life expectancy is lower than 90 days, and the index of their physical state (defined as the Karnofsky Index) is below 50. The terminally ill oncological patients are treatable with the palliative cures, representing a treatment system aimed at improving the quality of life (QOL) of both the patient and the family members, decreasing the physical and psychical sufferance of the patient. The present study followed 35 terminally ill oncological patients with bone metastases, at their homes, for the University of Catania. These patients had previously been followed by the Local Sanitary Unit (ASL 3) of Catania, and established a life expectancy not longer than 3 months. Independently from the basic neoplastic disease resulting in the bone metastases, all the patients were treated with sodium clodronate (SC) intravenously, 300 mg every second day, in order to decrease the bone pains. The visual analogue scale (VAS) for pain relief, the autonomy (IADL) and autosufficiency (ADL, Barthel Index) were evaluated after 1, 3, and 6 months of treatment. The results indicate an overall significant improvement both in the pain symptoms and the QOL. Also the compromised autonomy and autosufficiency of this population seemed to be improved, at least as compared to the predicted and expected results at the start of this trial, and also compared to the relevant literature. One can conclude that the i.v. application of 300 mg of SC every other day produced a significant pain reduction and improved the QOL, and helped in maintaining the actual autonomy and autosufficiency. On this basis we suggest the use of this compound in the given type of terminally ill patients.

Mutual augmentation of the induction of the histamine-forming enzyme, histidine decarboxylase, between alendronate and immuno-stimulants (IL-1, TNF, and LPS), and its prevention by clodronate

Nitrogen-containing bisphosphonates (N-BPs), powerful anti-bone-resorptive drugs, have inflammatory side effects, while histamine is not only an inflammatory mediator, but also an immuno-modifier. In murine models, a single intraperitoneal injection of an N-BP induces various inflammatory reactions, including the induction of the histamine-forming enzyme histidine decarboxylase (HDC) in tissues important in immune responses (such as liver, lungs, spleen, and bone marrow). Lipopolysaccharide (LPS) and the proinflammatory cytokines IL-1 and TNF are also capable of inducing HDC. We reported previously that in mice, (i) the inflammatory actions of N-BPs depend on IL-1, (ii) N-BP pretreatment augments both LPS-stimulated IL-1 production and HDC induction, and (iii) the co-administration of clodronate (a non-N-BP) with an N-BP inhibits the latter's inflammatory actions (including HDC induction). Here, we add the new findings that (a) pretreatment with alendronate (a typical N-BP) augments both IL-1- and TNF-induced HDC elevations, (b) LPS pretreatment augments the alendronate-induced HDC elevation, (c) co-administration of clodronate with alendronate abolishes these augmentations, (d) alendronate does not induce HDC in IL-1-deficient mice even if they are pretreated with LPS, and (e) alendronate increases IL-1beta in all tissues tested, but not in the serum. These results suggest that (1) there are mutual augmentations between alendronate and immuno-stimulants (IL-1, TNF, and LPS) in HDC induction, (2) tissue IL-1beta is important in alendronate-stimulated HDC induction, and (3) combination use of clodronate may have the potential to reduce the inflammatory effects of alendronate (we previously found that clodronate, conveniently, does not inhibit the anti-bone-resorptive activity of alendronate).

Ibandronate: efficacy in the treatment of metastatic bone disease

Ibandronate is a bisphosphonate treatment for metastatic bone disease. In Phase III trials in breast cancer patients, intravenous and oral formulations of ibandronate lowered the incidence of skeletal-related events, reduced metastatic bone pain scores throughout 2 years of treatment, and had significant positive effects on patient quality of life, demonstrating its efficacy in this condition. Recent pilot studies in other primary cancers suggest that a loading dose of ibandronate may relieve severe or opioid-resistant metastatic bone pain. In safety analyses, ibandronate was well tolerated with a safety profile comparable to placebo. Ibandronate therefore represents a treatment choice with documented efficacy and safety in metastatic bone disease from breast cancer.

Approaches to managing bone metastases from breast cancer: The role of bisphosphonates

Conventional management of metastatic bone disease involves local and systemic therapies in various combinations, along with symptomatic management to provide optimal care. In recent years, it has become clear that adding bisphosphonates to these treatments reduces the incidence and severity of skeletal complications. Bisphosphonates can also relieve metastatic bone pain and improve quality of life, although the extent to which they have demonstrated these effects may differ between agents. While bisphosphonates are the standard of care for the treatment of bone metastases, clinical trials are investigating additional indications for these agents, including the use of intensive dosing regimens for the relief of severe or opioid-resistant metastatic bone pain and adjuvant treatment for the prevention of bone metastases and cancer treatment-induced bone loss. Current and future indications demand effective, well-tolerated and convenient bisphosphonates, and the benefits of different drugs must be balanced against their limitations. The cost-effectiveness of bisphosphonate treatment is also a consideration, given the high economic burden of metastatic bone disease from breast cancer.

Breast cancer metastasis to bone: mechanisms of osteolysis and implications for therapy

The most common skeletal complication of breast cancer is osteolytic bone metastasis. Bone metastases are present in 80% of patients with advanced disease and cause significant morbidity. They are most often osteolytic, but can be osteoblastic or mixed. Tumor cells, osteoblasts, osteoclasts and bone matrix are the four components of a vicious cycle necessary for the initiation and development of bone metastases. Tumor cell gene expression is modified by interaction with bone-derived factors. For example, parathyroid hormone related protein (PTHrP), a tumor cell factor, is upregulated by bone-derived transforming growth factor beta (TGFbeta). Tumor cell factors, in turn, act upon bone cells to cause dysregulated bone destruction and formation. PTHrP increases osteoblast expression of RANK (receptor activator of NFkappaB) ligand which, in turn, activates osteoclasts. PTHrP-independent osteolytic factors, such as interleukin [IL]-11 and IL-8, also contribute to the vicious cycle. Other tumor-bone interactions, such as stimulation of tumor-homing through the CXCR4 chemokine receptor by its bone-derived ligand stromal-derived factor-1 (SDF-1), may be responsible for the site-specific predilection of breast cancer for bone. These factors and their roles in fueling the vicious cycle may identify novel targets for therapies to prevent metastasis.