Treatment of breast cancer with bone metastasis: bisphosphonate treatment - current and future. Int J Clin Oncol. 2008;13:18-23. [PMID: 18307015 DOI: 10.1007/s10147-007-0726-2]

Metastatic Breast Cancer, Organotropism and Therapeutics: A Review

The final stage of breast cancer involves spreading breast cancer cells to the vital organs like the brain, liver lungs and bones in the process called metastasis. Once the target organ is overtaken by the metastatic breast cancer cells, its usual function is compromised causing organ dysfunction and death. Despite the significant research on breast cancer metastasis, it's still the main culprit of breast cancer-related deaths. Exploring the complex molecular pathways associated with the initiation and progression of breast cancer metastasis could lead to the discovery of more effective ways of treating the devastating phenomenon. The present review article highlights the recent advances to understand the complexity associated with breast cancer metastases, organotropism and therapeutic advances.

Comparative Study of Neoadjuvant Chemotherapy With and Without Zometa for Management of Locally Advanced Breast Cancer With Serum VEGF as Primary Endpoint: The NEOZOL Study

INTRODUCTION

Neoadjuvant chemotherapy has become the treatment of choice for locally advanced breast cancer. Zoledronic acid (ZA) is a bisphosphonate initially used in the treatment of bone metastases because of its antibone resorption effect. Antitumor effects of ZA, including the inhibition of cell adhesion to mineralized bone or the antiangiogenic effect, have been demonstrated. However, the clinical significance of these effects remains to be determined.

MATERIALS AND METHODS

We undertook a multicenter open-label randomized trial to analyze the value of adding ZA to neoadjuvant chemotherapy for TNM clinical stage T2/T3 breast cancer. The primary endpoint was the evolution of serum VEGF.

RESULTS

The data from 24 patients were included in the ZA group and 26 in the control group. The evolution of serum VEGF was slightly in favor of ZA at 5.5 months (-0.7% vs. +7.5%), without reaching statistical significance (P = .52). The secondary endpoints were the breast conservation rate (higher with ZA; 83.3% vs. 65.4%; P = NS), pathologic complete response (no effect), and circulating tumor cells (odds ratio, 0.68 in favor of ZA; 95% confidence interval, 0.02-24.36). No cases of jaw necrosis or severe renal failure were observed in either group.

CONCLUSION

ZA is an antitumor drug of interest because of its multiple effects on tumor biology. Larger trials with longer follow-up that include additional endpoints such as relapse and survival rates would be of interest.

Design and synthesis of pyrimidinyl acyl thioureas as novel Hsp90 inhibitors in invasive ductal breast cancer and its bone metastasis

Invasive ductal carcinoma is the most common breast malignancies tumors and has tendency to bone metastases. Many oncogenic client proteins involved in formation of metastatic pathways. Stabilization, regulation, and maintenance of these oncogenic client proteins are provided with Heat Shock Protein 90 (Hsp90). Hsp90 perform these processes through its ATP binding and subsequent hydrolysis energy. Therefore, designing Hsp90 inhibitors is a novel cancer treatment method. However, many Hsp90 inhibitors have solubility problems and showed adverse effects in clinical trials. Thus, we designed and synthesized novel pyrimidinyl acyl thiourea derivatives to selectively inhibit Hsp90 alpha in human invasive ductal breast (MCF-7) and human bone osteosarcoma (Saos-2) cell lines. In vitro experiments showed that the compounds inhibited cell proliferation, ATP hydrolysis, and exhibited cytotoxic effect on these cancer cell lines. Further, gene expression was analyzed by microarray studies on MCF-7 cell lines. Several genes that play vital roles in breast cancer pathogenesis displayed altered gene expression in the presence of a selected pyrimidinyl acyl thiourea compound. Molecular docking studies were also performed to determine interaction between Hsp90 ATPase domain and pyrimidinyl acyl thiourea derivatives. The results indicated that the compounds are able to interact with Hsp90 ATP binding pocket and inhibit ATPase function. The designed compounds powerfully inhibit Hsp90 by an average of 1 μM inhibition constant. And further, the compounds perturb Hsp90 N terminal domain proper orientation and ATP may not provide required conformational change for Hsp90 function as evidenced by in silico experiments. Therefore, the designed compounds effectively inhibited both invasive ductal breast carcinoma and bone metastasis. Pyrimidinyl acyl thiourea derivatives may provide a drug template for effective treatment of invasive ductal breast carcinoma and its bone metastasis as well as new therapeutic perspective for drug design.

Osteocytic connexin hemichannels suppress breast cancer growth and bone metastasis

Although the skeleton is one of predominant sites for breast cancer metastasis, why breast cancer cells often become dormant after homing to bone is not well understood. Here, we reported an intrinsic self-defense mechanism of bone cells against breast cancer cells: a critical role of connexin (Cx) 43 hemichannels in osteocytes in the suppression of breast cancer bone metastasis. Cx43 hemichannels allow passage of small molecules between the intracellular and extracellular environments. The treatment of bisphosphonate drugs, either alendronate (ALN) or zoledronic acid (ZOL), opened Cx43 hemichannels in osteocytes. Conditioned media (CM) collected from MLO-Y4 osteocyte cells treated with bisphosphonates inhibited the anchorage-independent growth, migration and invasion of MDA-MB-231 human breast cancer cells and Py8119 mouse mammary carcinoma cells and this inhibitory effect was attenuated with Cx43(E2), a specific hemichannel blocking antibody. The opening of osteocytic Cx43 hemichannels by mechanical stimulation had similar inhibitory effects on breast cancer cells and this inhibition was attenuated by Cx43(E2) antibody as well. These inhibitory effects on cancer cells were mediated by ATP released from osteocyte Cx43 hemichannels. Furthermore, both Cx43 osteocyte-specific knockout mice and osteocyte-specific Δ130–136 transgenic mice with impaired Cx43 gap junctions and hemichannels showed significantly increased tumor growth and attenuated the inhibitory effect of ZOL. However, R76W transgenic mice with functional hemichannels but not gap junctions in osteocytes did not display a significant difference. Together, our studies establish the specific inhibitory role of osteocytic Cx43 hemichannels, and exploiting the activity of this channel could serve as a de novo therapeutic strategy.

Efficacy and Safety of Zoledronic Acid and Pamidronate Disodium in the Treatment of Malignant Skeletal Metastasis: A Meta-Analysis

Solid tumors frequently metastasize to bone. Two bisphosphonates have been investigated for bone metastases including pamidronate disodium and zoledronic acid.By searching the PubMed, Embase, Wanfang, and China National Knowledge Infrastructure (CNKI) databases, we conducted a meta-analysis to determine the efficacy and safety of zoledronic acid compared with pamidronate disodium in reducing pain in patients with bone metastases.Studies were pooled, and the relative risk (RR) and its corresponding 95 % confidence interval (CI) were calculated. Version 12.0 STATA software was used for statistical analysis. Twenty relevant articles were included for this meta-analysis study.The complete response rate in cancer patients treatment with zoledronic acid was significantly higher than that with pamidronate disodium (relative risk [RR] = 1.32 [95% confidence interval (CI), 1.00-1.75]; P = 0.987, I = 0%). However, there was no significant difference in the rate of partial response rate (RR = 1.04, 95% CI: 0.90-1.20; P = 0.942, I = 0%) and in the total effective rate (RR = 1.06, 95% CI: 1.00-1.12; P = 0.998, I = 0%). For adverse events (AE), the incidence of headache in cancer patients with zoledronic acid was significantly lower than that with pamidronate disodium (RR = 0.82, 95% CI: 0.70-0.96; P = 0.793, I = 0%). There was no significant difference in nausea or vomiting (RR = 1.00, 95% CI: 0.92-1.09; P = 0.494, I = 0%), fever (RR = 0.98, 95% CI: 0.85-1.14; P =0.633, I = 0%), fatigue (RR = 1.01, 95% CI: 0.91-1.11; P = 0.914, I = 0%) and anorexia (RR = 1.31, 95% CI: 0.91-1.87; P = 0.024, I = 64.4%).In conclusion, this meta-analysis indicates that treatment with zoledronic acid was more effective than pamidronate disodium in the complete response assessments and the incidence of headache, an AE, was significantly lower in cancer patients with zoledronic acid.

Concurrent use of strontium-89 with external beam radiotherapy for multiple bone metastases: early experience

OBJECTIVE

The aim of the present study was to consider the safety and efficacy of concurrent use of strontium-89 (Sr-89) with external beam radiotherapy (EBRT) for multiple bone metastases, including lesions that require urgent therapy.

METHODS

A retrospective review was performed of a consecutive series of patients who received Sr-89 for multiple bone metastases. Forty-five patients with multiple bone metastases received Sr-89 injection. Since 17 of the 45 patients had osteolytic bone lesions requiring emergent EBRT, they underwent concurrent use of Sr-89 with EBRT (concurrent group). The remaining 28 patients, none of whom had osteolytic lesions requiring urgent EBRT, were given Sr-89 injection only (singularity group). The injection of Sr-89 was to be given during EBRT, or on the day before the first day of EBRT. The dose of EBRT was 30 Gy in 10 fractions or 40 Gy in 20 fractions. Adverse events were evaluated according to hematological toxicity as measured by the Common Terminology Criteria for Adverse Events (V4.0). To assess efficacy, we checked changes in the pain scale and analgesic drug dosages, and the presence or absence of serious complications from bone metastases.

RESULTS

Fifteen of 17 patients (88.2%) in the concurrent group and 17 of 28 patients (60.7%) in the singularity group reported bone pain relief. A statistically significant difference was found between the two groups, and severe complications (spinal cord compression and pathological fracture) from bone metastases could be prevented in all patients in the concurrent group. Severe hematological toxicity (grade 3 or higher) was not observed in the two groups. There was no statistical difference between the two groups. No one required additional intervention. The adverse events were tolerable.

CONCLUSIONS

The results of our study suggest that concurrent use of Sr-89 with EBRT for multiple bone metastases can be performed safely if it is carried out with care, and that it may be an effective therapy in cases requiring emergency treatment.

Differential impact of adenosine nucleotides released by osteocytes on breast cancer growth and bone metastasis

Extracellular ATP has been shown to either inhibit or promote cancer growth and migration; however, the mechanism underlying this discrepancy remained elusive. Here we demonstrate the divergent roles of ATP and adenosine released by bone osteocytes on breast cancers. We showed that conditioned media (CM) collected from osteocytes treated with alendronate (AD), a bisphosphonate drug, inhibited the migration of human breast cancer MDA-MB-231 cells. Removal of the extracellular ATP by apyrase in CM abolished this effect, suggesting the involvement of ATP. ATP exerted its inhibitory effect through the activation of purinergic P2X receptor signaling in breast cancer cells evidenced by the attenuation of the inhibition by an antagonist, oxidized ATP, as well as knocking down P2X7 with small interfering RNA (siRNA), and the inhibition of migration by an agonist, BzATP. Intriguingly, ATP had a biphasic effect on breast cancer cells-lower dosage inhibited but higher dosage promoted its migration. The stimulatory effect on migration was blocked by an adenosine receptor antagonist, MRS1754, ARL67156, an ecto-ATPase inhibitor, and A2A receptor siRNA, suggesting that in contrast to ATP, adenosine, a metabolic product of ATP, promoted migration of breast cancer cells. Consistently, non-hydrolyzable ATP, ATPγS, only inhibited but did not promote cancer cell migration. ATP also had a similar inhibitory effect on the Py8119 mouse mammary carcinoma cells; however, adenosine had no effect owing to the absence of the A2A receptor. Consistently, ATPγS inhibited, whereas adenosine promoted anchorage-independent growth of MDA-MB-231 cells. Our in vivo xenograft study showed a significant delay of tumor growth with the treatment of ATPγS. Moreover, the extent of bone metastasis in a mouse intratibial model was significantly reduced with the treatment of ATPγS. Together, our results suggest the distinct roles of ATP and adenosine released by osteocytes and the activation of corresponding receptors P2X7 and A2A signaling on breast cancer cell growth, migration and bone metastasis.

Tumor regression of multiple bone metastases from breast cancer after administration of strontium-89 chloride (Metastron)

We report a case of tumor regression of multiple bone metastases from breast carcinoma after administration of strontium-89 chloride. This case suggests that strontium-89 chloride can not only relieve bone metastases pain not responsive to analgesics, but may also have a tumoricidal effect on bone metastases.

Immunohistochemical expression of caspase-3, caspase-5, caspase-7 and apoptotic protease-activating factor-1 (APAF-1) in the liver and kidney of rats exposed to zoledronic acid (ZOL) and basic fibroblast growth factor (bFGF)

BACKGROUND

Bisphosphonates (BPs) like zoledronic acid (ZOL) are widely used for the treatment of different diseases such as osteoporosis, metastatic bone diseases and hypercalcaemia. However, the effects of BPs on apoptosis of the liver and kidney after treatment are unclear. Furthermore, basic fibroblast growth factor (bFGF) is an angiogenic molecule, which plays an important role in angiogenesis and tissue repair. The present study investigated the expression of caspase-3, -5, -7 and apoptotic protease-activating factor-1 (APAF-1) in the liver and kidney of rats treated with ZOL and bFGF.

OBJECTIVE

The present study investigated the expression of caspase-3, -5, -7 and apoptotic protease-activating factor-1 (APAF-1) in the liver and kidney of rats treated with ZOL and bFGF.

ANIMALS AND METHODS

An animal model with 32 male Sprague Dawley rats was used. The effects of ZOL and bFGF on liver and kidney with the expressions of different apoptosis markers were studied histopathologically and immunohistochemically. Data were analyzed using Cronbach's alpha, Kruskal-Wallis and Bonnferroni-Dunn tests.

RESULTS

The main microscopic findings were mononuclear cell infiltrations around the bile ducts, binuclear and markedly enlarged hepatocytes (cytomegaly) and mitotic figures in the liver of rats treated with ZOL only. Immunohistochemically, both APAF-1 and caspase-3, -5 and -7 expressions were found elevated significantly (P < 0.05) in the liver and kidney of these rats.

CONCLUSIONS

Our findings showed that ZOL treatment increased while bFGF treatment decreased apoptosis significantly in the liver and kidney of Sprague Dawley rats.

CLINICAL IMPORTANCE

The addition of bFGF to ZOL treatment of various diseases might reduce the ZOL effects.

A cross-sectional survey of the diagnosis and management of bone metastasis in breast cancer patients in Turkey

Purpose

This study aimed to report the practice of managing breast cancer with bone metastasis in Turkey and to determine the adherence to the British Association of Surgical Oncology (BASO) guidelines.

Methods

This multicenter, cross-sectional epidemiological survey was conducted in 38 centers across Turkey. Data from 1,026 breast cancer patients with bone metastases (mean age 54.0 ± 11.9 years) were analyzed.

Results

Over 30 % of patients had a diagnosis of metastatic breast cancer (stage IV) at the time of primary diagnosis. The imaging modalities used for diagnosing bone metastases were bone scintigraphy (57.8 %), radiography (22.8 %), and bone survey (4.4 %). Tumor markers were detected in 94.9 %, and markers of bone metabolism were measured in 90.4 % of patients. A total of 3.5 % of patients underwent surgery for bone metastasis, 26.4 % underwent palliative chemotherapy (most commonly docetaxel + capecitabine), and 56.5 % endured radiotherapy. Most patients (96 %) also received bisphosphonate. Radiography, bone scintigraphy, and CT were the main imaging tools used for postoperative follow-up of bone metastasis. Our results were >95 % in line with the BASO guidelines for the management of bone metastasis, except that interventional procedures, such as biopsy, were applied less frequently in our survey.

Conclusions

The diagnosis and management practices of breast cancer with bone metastasis in Turkey were generally compatible with international guidelines. However, the awareness and knowledge of physicians on the current guidelines should be increased, and equipment for the appropriate interventional procedures should be provided in every clinic to obtain optimal and standard management of bone metastases.

Betulinic acid, a bioactive pentacyclic triterpenoid, inhibits skeletal-related events induced by breast cancer bone metastases and treatment

Many breast cancer patients experience bone metastases and suffer skeletal complications. The present study provides evidence on the protective and therapeutic potential of betulinic acid on cancer-associated bone diseases. Betulinic acid is a naturally occurring triterpenoid with the beneficial activity to limit the progression and severity of cancer, diabetes, cardiovascular diseases, atherosclerosis, and obesity. We first investigated its effect on breast cancer cells, osteoblastic cells, and osteoclasts in the vicious cycle of osteolytic bone metastasis. Betulinic acid reduced cell viability and the production of parathyroid hormone-related protein (PTHrP), a major osteolytic factor, in MDA-MB-231 human metastatic breast cancer cells stimulated with or without tumor growth factor-β. Betulinic acid blocked an increase in the receptor activator of nuclear factor-kappa B ligand (RANKL)/osteoprotegerin ratio by downregulating RANKL protein expression in PTHrP-treated human osteoblastic cells. In addition, betulinic acid inhibited RANKL-induced osteoclastogenesis in murine bone marrow macrophages and decreased the production of resorbed area in plates with a bone biomimetic synthetic surface by suppressing the secretion of matrix metalloproteinase (MMP)-2, MMP-9, and cathepsin K in RANKL-induced osteoclasts. Furthermore, oral administration of betulinic acid inhibited bone loss in mice intra-tibially inoculated with breast cancer cells and in ovariectomized mice causing estrogen deprivation, as supported by the restored bone morphometric parameters and serum bone turnover markers. Taken together, these findings suggest that betulinic acid may have the potential to prevent bone loss in patients with bone metastases and cancer treatment-induced estrogen deficiency.

Development of Raman spectral markers to assess metastatic bone in breast cancer

Bone is the most common site for breast cancer metastases. One of the major complications of bone metastasis is pathological bone fracture caused by chronic bone loss and degeneration. Current guidelines for the prediction of pathological fracture mainly rely on radiographs or computed tomography, which are limited in their ability to predict fracture risk. The present study explored the feasibility of using Raman spectroscopy to estimate pathological fracture risk by characterizing the alterations in the compositional properties of metastatic bones. Tibiae with evident bone destruction were investigated using Raman spectroscopy. The carbonation level calculated by the ratio of carbonate/phosphate ν1 significantly increased in the tumor-bearing bone at all the sampling regions at the proximal metaphysis and diaphysis, while tumor-induced elevation in mineralization and crystallinity was more pronounced in the metaphysis. Furthermore, the increased carbonation level is positively correlated to bone lesion size, indicating that this parameter could serve as a unique spectral marker for tumor progression and bone loss. With the promising advances in the development of spatially offset Raman spectroscopy for deep tissue measurement, this spectral marker can potentially be used for future noninvasive evaluation of metastatic bone and prediction of pathological fracture risk.

Orthopaedic perspective on bone metastasis

The incidence of cancer is increasing worldwide, with the advent of a myriad of new treatment options, so is the overall survival of these patients. However, from an orthopaedic perspective, there comes the challenge of treating more patients with a variety of metastatic bone lesions. The consequences of such lesions can be significant to the patient, from pain and abnormal blood results, including hypercalcemia, to pathological fracture. Given the multiple options available, the treatment of bone metastasis should be based on a patient-by patient manner, as is the case with primary bone lesions. It is imperative, given the various lesion types and locations, treatment of bone metastasis should be performed in an individualised manner. We should consider the nature of the lesion, the effect of treatment on the patient and the overall outcome of our decisions. The dissemination of primary lesions to distant sites is a complex pathway involving numerous cytokines within the tumour itself and the surrounding microenvironment. To date, it is not fully understood and we still base a large section of our knowledge on Pagets historic “seed and soil” theory. As we gain further understanding of this pathway it will allow us develop more medical based treatments. The treatment of primary cancers has long been provided in a multi-disciplinary setting to achieve the best patient outcomes. This should also be true for the treatment of bone metastases. Orthopaedic surgeons should be involved in the multidisciplinary treatment of such patients given that there are a variety of both surgical fixation methods and non-operative methods at our disposal.

Tetrahydrofurofuran-type lignans inhibit breast cancer-mediated bone destruction by blocking the vicious cycle between cancer cells, osteoblasts and osteoclasts

Breast cancer frequently spreads to bone. The interaction between bone metastases and microenvironment, referred as the "vicious cycle", increases both tumor burden and bone destruction. Therefore, inhibition at any point in this "vicious cycle" can reduce malignant osteolytic lesions in patients with advanced breast cancer. In this study, we evaluated whether tetrahydrofurofuran-type lignans derived from Magnoliae Flos, commonly used in traditional Asian medicine to treat inflammatory diseases, could block breast cancer-mediated bone loss. Aschatin, fargesin, lirioresinol B dimethyl ether, and magnolin at noncytotoxic concentrations suppressed mRNA expression and secretion of osteolytic factor PTHrP in MDA-MB-231 metastatic human breast cancer cells. Fargesin inhibited TGF-β-stimulated cell viability, migration, and invasion and decreased TGF-β-induced PTHrP production in MDA-MB-231 cells. In addition, these lignans reduced RANKL/OPG ratio in PTHrP-treated hFOB1.19 human osteoblastic cells and inhibited RANKL-mediated osteoclast differentiation in mouse bone marrow macrophages. Aschatin, fargesin, lirioresinol B dimethyl ether, and magnolin substantially reduced bone-resorbing activity of osteoclasts by inhibiting MMP-9 and cathepsin K activities. Furthermore, orally administered fargesin inhibited tumor growth and cancer-mediated bone destruction in mice with MDA-MB-231 cells injected into calvarial tissues. Aschatin, fargesin, lirioresinol B dimethyl ether, and magnolin blocked initiation and progression of the "vicious cycle" between breast cancer metastases and bone microenvironment by inhibiting PTHrP production in breast cancer cells and osteoclastic bone resorption. Therefore, these tetrahydrofurofuran-type lignans have the potential to serve as beneficial agents to prevent and treat cancer-induced bone destruction in breast cancer patients.

Denosumab and the current status of bone-modifying drugs in breast cancer

BACKGROUND

Bone-modifying therapy is a primary research interest in breast cancer. Several features contribute to the importance of the bone environment in the management of breast cancer. Firstly, bone metastases represent the most common site of breast cancer metastases and secondly, the emergence of cancer treatment-induced bone loss (CTIBL) among breast cancer survivors and patients is of increasing concern. Furthermore, concordant with the "seed and soil" theory, agents that alter the bone microenvironment may even prevent tumor cell seeding in bone and limit cancer growth.

MATERIAL AND METHODS

Medical databases and conference proceedings were searched to identify articles, abstracts and clinical trials that have or are investigating denosumab and bisphosphonates in cancer therapy. Our search included a predefined focus on bone-modifying therapies in early and advanced breast cancer.

RESULTS AND DISCUSSION

Bisphosphonates (BPs) have an established role both in the prevention and treatment of CTIBL and have been studied in the adjuvant setting for early breast cancer (EBC). Denosumab is a monoclonal antibody directed against RANK ligand and thereby inhibits osteoclastogenesis and bone resportion. It is the newest agent approved for the treatment of postmenopausal osteoporosis and the prevention of skeletal-related events (SRE) in cancer patients with solid tumors and bone metastases. Denosumab has a favorable toxicity profile in comparison to BPs and has the potential to improve cancer outcomes.

CONCLUSION

This review examines the existing role of denosumab in the treatment of bone complications of breast cancer and its potential role as adjuvant therapy.

Combinations of bisphosphonates and classical anticancer drugs: a preclinical perspective

Bone metastases are frequent complications in advanced breast and prostate cancer among others, resulting in increased risk of fractures, pain, hypercalcaemia of malignancy and a reduction in patient independence and mobility. Bisphosphonates (BPs) are in wide clinical use for the treatment of cancer-induced bone disease associated with advanced cancer, due to their potent ability to reduce skeletal-related events (SREs) and improve quality of life. Despite the profound effect on bone health, the majority of clinical studies have failed to demonstrate an overall survival benefit of BP therapy. There is increasing preclinical evidence to suggest that inclusion of the most potent nitrogen-containing BPs (NBPs) in combination therapy results in increased antitumour effects and improved survival, but that the particular schedules used are of key importance to achieve optimal benefit. Recent clinical data have suggested that there may be effects of adjuvant NBP therapy on breast tumours outside the skeleton. These findings have led to renewed interest in the use of BPs in cancer therapy, in particular how they can be included as part of adjuvant protocols. Here we review the key data reported from preclinical model systems investigating the effects of combination therapy including BPs with particular emphasis on breast and prostate cancer.

Concurrent use of Sr-89 chloride with zoledronic acid is safe and effective for breast cancer patients with painful bone metastases

Our aim in this study was to examine the safety and efficacy of the concurrent use of the radiopharmaceutical strontium-89 (Sr-89) chloride with zoledronic acid in standard anticancer therapy for breast cancer patients with painful multifocal bone metastases. The study comprised 16 breast cancer patients with painful multifocal bone metastases detected by bone scintigraphy, computed tomography or magnetic resonance imaging. All patients were treated with Sr-89 and zoledronic acid concurrently between March 2007 and February 2011 as part of a standard therapeutic regimen comprising chemotherapy, endocrine therapy, molecular targeting therapy and targeted radiotherapy. Sr-89 was administered intravenously at 2 MBq/kg to a maximum of 141 MBq per person. Safety was evaluated according to myelotoxicity as measured by the Common Terminology Criteria for Adverse Events (v3.0). To assess treatment efficacy, we monitored changes in analgesic drug dosages. Furthermore, bremsstrahlung imaging after the administration of Sr-89 was utilized to examine the relationship between the accumulation of Sr-89 in metastatic sites and treatment efficacy. Based on the results, a total of 14 out of 16 patients (88%) reported bone pain relief, indicating a high efficacy of Sr-89 combined with zoledronic acid. In responsive cases, a strong uptake of Sr-89 was observed on bremsstrahlung imaging at the same sites indicated by (99m)Tc bone scintigraphy. Moreover, severe myelosuppression (> grade 3) was not observed, and adverse events were tolerable. In conclusion, the use of Sr-89 with zoledronic acid in breast cancer patients with painful bone metastases was safe and effective when administered concurrently with other standard therapies. In the future, the treatment with Sr-89 at the early stage should be considered, and a large-scale clinical study should be conducted.

Magnetic resonance guided high-intensity focused ultrasound ablation of musculoskeletal tumors

This article reviews the fundamental principles and clinical experimental uses of magnetic resonance guided high-intensity focused ultrasound (MRgHIFU) ablation of musculoskeletal tumors. MRgHIFU is a noninvasive treatment modality that takes advantage of the ability of magnetic resonance to measure tissue temperature and uses this technology to guide high-intensity focused ultrasound waves to a specific focus within the human body that results in heat generation and complete thermal necrosis of the targeted tissue. Adjacent normal tissues are spared because of the accurate delivery of thermal energy, as well as, local blood perfusion that provides a cooling effect. MRgHIFU is approved by the Food and Drug Administration for the treatment of uterine fibroids and is used on an experimental basis to treat breast, prostate, liver, bone, and brain tumors.

Skeletal imaging effects of pamidronate therapy in osteosarcoma patients

BACKGROUND

After observing metaphyseal changes in pediatric and young adult patients with osteosarcoma who were treated with pamidronate, we initiated a retrospective study to identify bone findings on computed radiography of the chest and extremities, chest CT, extremity MRI, and radionuclide bone scans in this population.

OBJECTIVE

To review the generalized skeletal imaging findings on computed radiography, CT, and MR examinations in patients with osteosarcoma (OS) receiving pamidronate.

MATERIALS AND METHODS

A retrospective review of 40 patients with newly diagnosed OS (mean age, 16.5 years) receiving pamidronate with chemotherapy were identified at one institution. Computed radiography, CT, MR, and bone scans on 36 patients were reviewed for osseous changes.

RESULTS

Dense metaphyseal bands at the growth plates in long bones, epiphyseal ossification centers, anterior rib ends, sternum and spine were observed. Osseous changes occurred on CT in 69% of patients, and on computed chest radiography in 53%. Bone-within-bone appearance in the spine and ossification centers was identified on computed radiography in 36%.

CONCLUSION

OS patients treated with pamidronate can develop metaphyseal sclerotic bands as well as epiphyseal and vertebral endplate sclerosis progressing to a bone-within-bone appearance. Findings occur more frequently in younger patients with open epiphyses.

Effects of continuous combined hormone replacement therapy and clodronate on bone mineral density in osteoporotic postmenopausal women: a 5-year follow-up

OBJECTIVE

To determine the effects of HRT with or without clodronate on bone mineral density (BMD) change and bone turnover markers.

DESIGN

Prospective, partly randomized trial.

SETTING

Kuopio University Hospital, Finland.

POPULATION

167 osteoporotic women (61+/-2.7 years; T-score<or=-2.5 SD).

METHODS

Estradiol 2 mg+NETA 1 mg, randomization to additional 800 mg clodronate (n=55, HT+C-group) or placebo (n=55, HT-group); if contraindications to HRT, clodronate (n=57, C-group).

MAIN OUTCOME MEASURES

BMD by DXA after 1, 3 and 5 years, serum osteocalcin (OC) and bone-specific alkaline phosphatase (BAP) at the baseline and after 3 years.

RESULTS

After 5 years, adjusted lumbar BMD increased by 4.2% in the HT-group and 3.7% in the HT+C-group. The C-group showed a decrease of -1.1%, the total difference being 5.3% and 4.8% between HT, HT+C vs. C-group, respectively (p<0.001). In the femoral neck, the adjusted 5-year BMD benefit was 1.3% and 2.4% in the HT- and HT+C-groups, respectively, the net loss of BMD in the C-group was -3.3% (p<0.05 between HT+C vs. C). By 3 years, OC decreased by 55.0%, 70.3% and 53.8% in the HT-, HT+C- and C-groups, respectively (p<0.001 vs. baseline). The significant decreases of BAP were 39.4% in the HT-group, 42.1% in the HT+C-group and 30.2% in the C-group with no significant differences between the groups after adjustments.

CONCLUSIONS

In postmenopausal women with osteoporosis, HRT increased spinal and femoral BMD, but the combination of HRT and clodronate did not offer an extra gain of bone mass.

Modifications to the dNTP triphosphate moiety: from mechanistic probes for DNA polymerases to antiviral and anti-cancer drug design

Abnormal replication of DNA is associated with many important human diseases, most notably viral infections and neoplasms. Existing approaches to chemotherapeutics for diseases associated with dysfunctional DNA replication classically involve nucleoside analogues that inhibit polymerase activity due to modification in the nucleobase and/or ribose moieties. These compounds must undergo multiple phosphorylation steps in vivo, converting them into triphosphosphates, in order to inhibit their targeted DNA polymerase. Nucleotide monophosphonates enable bypassing the initial phosphorylation step at the cost of decreased bioavailability. Relatively little attention has been paid to higher nucleotides (corresponding to the natural di- and triphosphate DNA polymerase substrates) as drug platforms due to their expected poor deliverability. However, a better understanding of DNA polymerase mechanism and fidelity dependence on the triphosphate moiety is beginning to emerge, aided by systematic incorporation into this group of substituted methylenebisphosphonate probes. Meanwhile, other bridging, as well as non-bridging, modifications have revealed intriguing possibilities for new drug design. We briefly survey some of this recent work, and argue that the potential of nucleotide-based drugs, and intriguing preliminary progress in this area, warrant acceptance of the challenges that they present with respect to bioavailability and metabolic stability.

Mechanisms of bone metastases of breast cancer

Cancer development is a multi-step process driven by genetic alterations that elicit the progressive transformation of normal human cells into highly malignant derivatives. The altered cell proliferation phenotype of cancer involves a poorly characterized sequence of molecular events, which often result in the development of distant metastasis. In the case of breast cancer, the skeleton is among the most common of metastatic sites. In spite of its clinical importance, the underlying cellular and molecular mechanisms driving bone metastasis remain elusive. Despite advances in our understanding of the phenotype of cancer cells, the increased focus on the contribution of the tumor microenvironment and the recent revival of interest in the role of tumor-propagating cells (so called cancer stem cells) that may originate or be related to normal stem cells produced in the bone marrow, many important questions remain unanswered. As such, a more complete understanding of the influences of both the microenvironment and the tumor phenotype, which impact the entire multi-step metastatic cascade, is required. In this review, the importance of tumor heterogeneity, tumor-propagating cells, the microenvironment of breast cancer metastasis to bone as well as many current endocrine therapies for the prevention and treatment of metastatic breast cancer is discussed.

Calcium-sensing receptor in cancer: good cop or bad cop?

The extracellular calcium-sensing receptor (CaR) is a versatile 'sensor' for di- and polycationic molecules in the body. CaR plays a key role in the defense against hypercalcemia by "sensing" extracellular calcium levels in the parathyroid and kidney, the key organs maintaining systemic calcium homeostasis. Although mutation of CaR gene has so far not been associated with any malignancy, aberrant functions of CaR have implications in malignant progression. One situation is loss of CaR expression, resulting in loss of growth suppressing effects of elevated extracellular Ca(2+) by CaR, reported in parathyroid adenoma and in colon carcinoma. Another situation is activation of CaR, resulting in increased production of parathyroid hormone-related peptide (PTHrP), a primary causal factor in hypercalcemia of malignancy and a contributor to metastatic processes involving bone. CaR signaling and effects have been studied in several cancers including ovarian cancers, gastrinomas, and gliomas in addition to comparatively detailed studies in breast, prostate, and colon cancers. Studies on H-500 rat Leydig cells, a xenotransplantable model of humoral hypercalcemia of malignancy has shed much light on the mechanisms of CaR-induced cancer cell growth and survival. Pharmacological agonists and antagonists of CaR hold therapeutic promise depending on whether activation of CaR is required such as in case of colon cancer or inactivating the receptor is required as in the case of breast- and prostate tumors.

Bisphosphonate administration prior to tooth extraction delays initial healing of the extraction socket in rats

Bisphosphonates (BPs) are clinically used for the treatment of bone metabolic abnormalities because they are powerful inhibitors of bone resorption. Osteonecrosis of the jaw has been observed after tooth extraction in a considerable number of BP-treated cancer patients, but the reason for this is not known. We studied the effects of BP on extraction socket healing in rats that were pretreated with BP prior to tooth extraction. Male Wistar rats (approximately 5 weeks old) were divided into experimental (BP) and control groups. In both groups, maxillary right second molars were extracted under general anesthesia. BP group rats were injected with 50 microl (1.0 mg/kg) alendronate into the right buccal alveolar bone every 4 days for 14 days, starting 2 days before tooth extraction. Control group rats were injected with physiological saline instead of alendronate. Rats were euthanized 3, 7, 10 or 14 days after tooth extraction, and maxillary bones were collected. Bone morphometric analysis using microfocus X-ray CT images and calculation of bone-resorption parameters based on hematoxylin and eosin or TRAP-stained pathological sections of the molar region showed that new bone formation in the extraction socket was delayed in the BP group relative to the control group during the first 7 days after extraction. A subsequent increase in new bone formation showed that bone resorption in the BP rats was eventually inhibited. This delay in initial healing may explain the jaw osteonecrosis observed in some BP-treated cancer patients.

An osteoclast-targeting agent for imaging and therapy of bone metastasis

A hybrid compound (DO3A-BP) featuring a radiometal bifunctional chelator (1,4,7,10-tetraazacyclotetradecane-N,N',N'',N'''-tetraacetic acid, DOTA) and an osteoclast-targeting moiety (bisphosphonate) was designed and synthesized. The (111)In-labeled complex of DO3A-BP showed significantly elevated uptake in osteoclasts compared to the undifferentiated adherent bone marrow derived cells. Biodistribution studies revealed a favorable tissue distribution profile in normal mice with high bone uptake and long retention, and low or negligible accumulation in non-target organs.