Antitumor effects of bisphosphonates: promising preclinical evidence

Treatment affects load to failure and microdamage accumulation in healthy and osteolytic rat vertebrae

Bone turnover and microdamage are impacted by the presence of skeletal metastases which can contribute to increased fracture risk. Treatments for metastatic disease may further impact bone quality. This exploratory study aimed to establish an initial understanding of microdamage accumulation and load to failure in healthy and osteolytic rat vertebrae following focal and systemic cancer treatment (docetaxel (DTX), stereotactic body radiotherapy (SBRT), or zoledronic acid (ZA)). Osteolytic spine metastases were developed in 6-week-old athymic female rats via intracardiac injection of HeLa human cervical cancer cells (day 0). Additional rats served as healthy controls. Rats were either untreated, received SBRT to the T10-L6 vertebrae on day 14 (15 Gy, two fractions), DTX on day 7 or 14, or ZA on day 7. Rats were euthanized on day 21. Tumor burden was assessed with bioluminescence images acquired on day 14 and 21, histology of the excised T11 and L5 vertebrae, and ex-vivo μCT images of the T13-L4. Microstructural parameters (bone volume/total volume, trabecular number, spacing, thickness, and bone mineral density) were measured from L2 vertebrae. Load to failure was measured with axial compressive loading of the L1-L3 motion segments. Microdamage accumulation was labeled in T13 vertebrae with BaSO4 staining and was visualized with high resolution μCT imaging. Microdamage volume fraction was defined as the ratio of BaSO4 to bone volume. DTX administered on day 7 reduced tumor growth significantly (p < 0.05). Microdamage accumulation was found to be increased by the presence of metastases but was reduced by all treatments with ZA showing the largest improvement in HeLa cell injected rats. Load to failure was decreased in untreated and SBRT HeLa cell injected rats compared to healthy controls (p < 0.01). There was a moderate negative correlation between load to failure and microdamage volume fraction in vertebrae from rats injected with HeLa cells (R = -0.35, p = 0.031). Strong correlations were also found between microstructural parameters and load to failure and microdamage accumulation. Several factors, including the presence of osteolytic lesions and use of cancer therapies, influence microdamage accumulation and load to failure in rat vertebrae. Understanding the impact of these treatments on fracture risk of metastatic vertebrae is important to improve management of patients with spinal metastases.

Bone Metastasis of Breast Cancer: Molecular Mechanisms and Therapeutic Strategies

Bone metastasis is a common complication of many types of advanced cancer, including breast cancer. Bone metastasis may cause severe pain, fractures, and hypercalcemia, rendering clinical management challenging and substantially reducing the quality of life and overall survival (OS) time of breast cancer patients. Studies have revealed that bone metastasis is related to interactions between tumor cells and the bone microenvironment, and involves complex molecular biological mechanisms, including colonization, osteolytic destruction, and an immunosuppressive bone microenvironment. Agents inhibiting bone metastasis (such as bisphosphate and denosumab) alleviate bone destruction and improve the quality of life of breast cancer patients with bone metastasis. However, the prognosis of these patients remains poor, and the specific biological mechanism of bone metastasis is incompletely understood. Additional basic and clinical studies are urgently needed, to further explore the mechanism of bone metastasis and develop new therapeutic drugs. This review presents a summary of the molecular mechanisms and therapeutic strategies of bone metastasis of breast cancer, aiming to improve the quality of life and prognosis of breast cancer patients and provide a reference for future research directions.

The presenting dental status of solid tumours with bone metastases requiring bone-targeting agents - part 1: an overview

Introduction Dental pre-assessment before bone-targeting agents (BTA) in oncology patients is a well-recognised practice; yet, guidance on this has typically been unable to differentiate between the intricacies of varying oncology groups. This study assesses the presenting dental status of oncology patients with bone metastases (BM) due to commence BTA, to determine whether differences exist with varying tumour groups.Materials and methods Data were retrospectively collected from a dedicated pre-BTA dental assessment clinic. Statistical analysis and observational data were used to compare patient and tumour demographics as well as to their peers via the Adult Dental Health Survey.Results A total of 492 patients with a solid tumour diagnosis and BM requiring BTA were included in this retrospective study. Demographics such as sex, age, smoking status and tumour site were all significant for the number of teeth present (p = 0.000). Furthermore, survival data post-BTA identified prostate, breast and thyroid groups surviving over 12 months following dental assessment (p <0.000). In contrast, the remaining groups such as lung, colorectal and gastrointestinal had poorer outcomes (p <0.000).Conclusion Pre-BTA dental assessment should consider and incorporate additional patient and tumour demographics to allow for a tailored and personalised dental treatment plan. Application of this principle would look to optimise oral function while considering tumour prognosis to avoid over- or under-prescribing pre-BTA dental treatment.

Systemic effects of abnormal bone resorption on muscle, metabolism, and cognition

Skeletal tissue is dynamic, undergoing constant remodeling to maintain musculoskeletal integrity and balance in the human body. Recent evidence shows that apart from maintaining homeostasis in the local microenvironment, the skeleton systemically affects other tissues. Several cancer-associated and noncancer-associated bone disorders can disrupt the physiological homeostasis locally in the bone microenvironment and indirectly contribute to dysregulation of systemic body function. The systemic effects of bone on the regulation of distant organ function have not been widely explored. Recent evidence suggests that bone can interact with skeletal muscle, pancreas, and brain by releasing factors from mineralized bone matrix. Currently available bone-targeting therapies such as bisphosphonates and denosumab inhibit bone resorption, decrease morbidity associated with bone destruction, and improve survival. Bisphosphonates have been a standard treatment for bone metastases, osteoporosis, and cancer treatment-induced bone diseases. The extraskeletal effects of bisphosphonates on inhibition of tumor growth are known. However, our knowledge of the effects of bisphosphonates on muscle weakness, hyperglycemia, and cognitive defects is currently evolving. To be able to identify the molecular link between bone and distant organs during abnormal bone resorption and then treat these abnormalities and prevent their systemic effects could improve survival benefits. The current review highlights the link between bone resorption and its systemic effects on muscle, pancreas, and brain.

Early Changes of VEGF Levels After Zoledronic Acid in Women With Postmenopausal Osteoporosis: A Potential Role of Vitamin D

Zoledronic acid (Zol) is a widely used intravenous aminobisphosphonate to treat both benign and malignant skeletal diseases, and bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a serious side effect whose pathophysiology remains poorly understood. Vascular Endothelial Growth Factor (VEGF) has been recognized to mediate BRONJ in cancer patients undergoing Zol treatment, however data on VEGF are lacking in patients with osteoporosis. Increasing evidences demonstrate that vitamin D influences VEGF levels. The aim of this study was to investigate the influence of Zol on VEGF levels and the possible role for vitamin D on the Zol mediated changes of VEGF concentration in women with postmenopausal osteoporosis. Twenty-eight postmenopausal women with osteoporosis were enrolled and randomized into two groups to receive Zol (5 mg) or placebo. At baseline, at day-3 and day-30 VEGF serum levels were measured; bone turnover markers, 25-hydroxyvitamin D [25(OH)D] and serum calcium were evaluated at baseline. In Zol-treated women, VEGF increased significantly on day-3, and then decreased on day-30. In the Zol-treated women, the percent change of VEGF levels between baseline and day-30 (-18% at day-30 vs. baseline, p = 0.01) was significantly associated with serum 25(OH)D values (r = 0.29, p = 0.028). At a stepwise multiple regression analysis, after correcting for age, BMI, time since menopause, femoral neck BMD, osteocalcin, C-terminal telopeptide of type 1 collagen, and baseline VEGF levels, 25(OH)D levels were independently associated with VEGF change (β = 1.7, SE = 0.71, p = 0.03). For the first time, we detected early modifications of circulating VEGF in postmenopausal women receiving Zol for osteoporosis, identifying a vitamin D-dependent modulation of these changes.

Botter S. Inhibition of the activin receptor signaling pathway: A novel intervention against osteosarcoma

Osteosarcoma is a cancer of pathological bone remodeling with high mortality and severe comorbidity. New therapies are urgently needed. Activin A, a member of the transforming growth factor β (TGFβ) superfamily, has been suggested to stimulate proliferation and invasion of osteosarcoma cells in vitro, thus representing a potential therapeutic target. In this study, inhibition of the activin receptor signaling pathway was explored as a therapy for osteosarcoma. In a murine intratibial osteosarcoma xenograft model, two types of inhibitors were tested: (a) a soluble activin type IIA decoy receptor (ActRIIA-mFc), or (b) a modified variant of follistatin (FSTΔHBS -hFc), either alone or in combination with a bisphosphonate. Both inhibitors reduced primary tumor development by nearly 50% compared to vehicle treatment. When ActRIIA-mFc was combined with bisphosphonate, the effect on tumor size became even more pronounced (78% reduction vs. vehicle). Moreover, FSTΔHBS -hFc increased body weight in the face of tumor progression (14% increase vs. vehicle), and ActRIIA-mFc reduced the number of lung metastases when combined with bisphosphonate. The present study demonstrates a novel approach to treating osteosarcoma and encourages further investigation of inhibition of the activin receptor signaling pathway as an intervention against the disease.

Bisphosphonates and risk of cancers: a systematic review and meta-analysis

Background

It is unclear whether bisphosphonates are associated with risk of cancers. Therefore, this meta-analysis aimed to evaluate the effect of bisphosphonates on overall cancers.

Methods

A search in Pubmed, Embase, Cochrane Library and Web of Science databases was conducted, from the inception date of each resource to September 26, 2019. The summarised effect estimates with 95% CIs were calculated using a random-effect model. Heterogeneity and publication bias were explored.

Results

Thirty-four articles were included in this study (4,508,261 participants; 403,196 cases). The results revealed that bisphosphonates significantly decreased the risk of colorectal cancer (RR = 0.89, 95% CI: 0.81–0.98), breast cancer (RR = 0.87, 95% CI: 0.82–0.93) and endometrial cancer (RR = 0.75, 95% CI: 0.61–0.94), but no significant association was observed in all-cause cancer. Furthermore, nitrogen-containing bisphosphonates only had protective effects both on breast cancer (RR = 0.94, 95% CI: 0.90–0.99) and endometrial cancer (RR = 0.70, 95% CI: 0.54–0.92). Non-nitrogen-containing bisphosphonates tended to increase the risk of liver cancer (RR = 2.14, 95% CI: 1.23–3.72) and pancreas cancer (RR = 1.75, 95% CI: 1.32–2.33).

Conclusion

Bisphosphonates are significantly associated with risk reduction of colorectal, breast and endometrial cancer, especially nitrogen-containing bisphosphonates. It should be noted that non-nitrogen-containing bisphosphonates might increase the risk of liver and pancreas cancer. Large prospective cohort studies are needed to find the causal association between bisphosphonates and risk of cancers.

ATRAID regulates the action of nitrogen-containing bisphosphonates on bone

Nitrogen-containing bisphosphonates (N-BPs), such as alendronate, are the most widely prescribed medications for diseases involving bone, with nearly 200 million prescriptions written annually. Recently, widespread use of N-BPs has been challenged due to the risk of rare but traumatic side effects such as atypical femoral fracture (AFF) and osteonecrosis of the jaw (ONJ). N-BPs bind to and inhibit farnesyl diphosphate synthase, resulting in defects in protein prenylation. Yet, it remains poorly understood what other cellular factors might allow N-BPs to exert their pharmacological effects. Here, we performed genome-wide studies in cells and patients to identify the poorly characterized gene, ATRAID Loss of ATRAID function results in selective resistance to N-BP-mediated loss of cell viability and the prevention of alendronate-mediated inhibition of prenylation. ATRAID is required for alendronate inhibition of osteoclast function, and ATRAID-deficient mice have impaired therapeutic responses to alendronate in both postmenopausal and senile (old age) osteoporosis models. Last, we performed exome sequencing on patients taking N-BPs that suffered ONJ or an AFF. ATRAID is one of three genes that contain rare nonsynonymous coding variants in patients with ONJ or an AFF that is also differentially expressed in poor outcome groups of patients treated with N-BPs. We functionally validated this patient variation in ATRAID as conferring cellular hypersensitivity to N-BPs. Our work adds key insight into the mechanistic action of N-BPs and the processes that might underlie differential responsiveness to N-BPs in people.

Alendronate improves fasting plasma glucose and insulin sensitivity, and decreases insulin resistance in prediabetic osteopenic postmenopausal women: A randomized triple-blind clinical trial

AIMS/INTRODUCTION

Postmenopausal women receive bisphosphonates for osteoporosis treatment. The effect of these medications on developing diabetes mellitus in prediabetic patients is yet to be investigated. We aimed to determine the effect of alendronate on plasma glucose, insulin indices of postmenopausal women with prediabetes and osteopenia.

MATERIALS AND METHODS

The present triple-blind randomized controlled clinical trial included 60 postmenopausal women, aged 45-60 years. All patients were vitamin D sufficient. They were randomly enrolled in intervention (70 mg/week alendronate for 12 weeks) and control (placebo tablet per week for 12 weeks) groups. The morning 8-h fasting blood samples were collected at the baseline and follow-up visits to measure the fasting plasma glucose (mg/dL), insulin and hemoglobin A1c (HbA1c). Plasma glucose and insulin concentration were measured 30, 60 and 120 min after the glucose tolerance test. The Matsuda Index, homeostasis model assessment of insulin resistance, homeostasis model assessment of β-cell function and the area under the curves of glucose and insulin were calculated.

RESULTS

The mean (standard deviation) fasting plasma glucose (102.43 [1.46] mg/dL vs 94.23 [1.17] mg/dL, P = 0.001), 120-min insulin concentration (101.86 [15.70] mU/L vs 72.60 [11.36] mU/L, P = 0.026), HbA1c (5.60 [0.06]% vs 5.40 [0.05]%, P = 0.001), homeostasis model assessment of insulin resistance (3.57 [0.45] vs 2.62 [0.24], P = 0.021) and Matsuda Index (7.7 [0.41] vs 9.2 [0.4], P = 0.001) significantly improved in the alendronate-treated group. There were more statistically significant reductions in fasting plasma glucose (-8.2 [8.63] mg/dL vs -2.5 [14.26] mg/dL, P = 0.002) and HbA1c (-0.2 [0.23]% vs -0.09 [0.26]%, P = 0.015) observed in the alendronate-treated group than the placebo group during the study course, respectively.

CONCLUSIONS

Administration of 70 mg/week alendronate improves fasting plasma glucose, HbA1c and insulin indices in postmenopausal women.

Zoledronic Acid-containing Nanoparticles With Minimum Premature Release Show Enhanced Activity Against Extraskeletal Tumor

Bisphosphonates are generally used to treat bone diseases, such as bone metastasis from cancer. There is evidence that, through the modification of the pharmacokinetics and biodistribution of bisphosphonates by formulating them into nanoparticles, they may be able to treat extraskeletal tumors. However, many previously reported bisphosphonate nanoparticle formulations show extensive premature release of bisphosphonates. Herein, using zoledronate (Zol), a third-generation bisphosphonate, we developed a new Zol nanoparticle formulation (denoted as Zol-NPs) by encapsulating anionic lipid-coated Zol-calcium nanocomplexes into poly(lactic- co-glycolic) acid nanoparticles emulsified with octadecanoic acid-hydrazone-polyethylene glycol (2000), an acid-sensitive cleavable emulsifying agent. The resultant Zol-NPs, about 180 nm in hydrodynamic diameter, show very limited premature release of Zol (i.e., <5% in 48 h in a simulated physiological condition) and enhanced cytotoxicity to both murine cancer cells and macrophages. In a mouse model with orthotopically transplanted mammary tumors, Zol-NPs significantly reduced the distribution of Zol in bones, but increased its distribution in tumors. Importantly, Zol-NPs also significantly inhibited tumor growth, whereas the equivalent dose of free Zol did not. This platform technology may be exploited to treat extraskeletal tumors with bisphosphonates.

Removal of matrix-bound zoledronate prevents post-extraction osteonecrosis of the jaw by rescuing osteoclast function

Unlike other antiresorptive medications, bisphosphonate molecules accumulate in the bone matrix. Previous studies of side-effects of anti-resorptive treatment focused mainly on systemic effects. We hypothesize that matrix-bound bisphosphonate molecules contribute to the pathogenesis of bisphosphonate-related osteonecrosis of the jaw (BRONJ). In this study, we examined the effect of matrix-bound bisphosphonates on osteoclast differentiation in vitro using TRAP staining and resorption assay, with and without pretreatment with EDTA. We also tested the effect of zoledronate chelation on the healing of post-extraction defect in rats. Our results confirmed that bisphosphonates bind to, and can be chelated from, mineralized matrix in vitro in a dose-dependent manner. Matrix-bound bisphosphonates impaired the differentiation of osteoclasts, evidenced by TRAP activity and resorption assay. Zoledronate-treated rats that underwent bilateral dental extraction with unilateral EDTA treatment showed significant improvement in mucosal healing and micro-CT analysis on the chelated sides. The results suggest that matrix-bound bisphosphonates are accessible to osteoclasts and chelating agents and contribute to the pathogenesis of BRONJ. The use of topical chelating agents is a promising strategy for the prevention of BRONJ following dental procedures in bisphosphonate-treated patients.

Understanding the Progression of Bone Metastases to Identify Novel Therapeutic Targets

Bone is one of the most preferential target site for cancer metastases, particularly for prostate, breast, kidney, lung and thyroid primary tumours. Indeed, numerous chemical signals and growth factors produced by the bone microenvironment constitute factors promoting cancer cell invasion and aggression. After reviewing the different theories proposed to provide mechanism for metastatic progression, we report on the gene expression profile of bone-seeking cancer cells. We also discuss the cross-talk between the bone microenvironment and invading cells, which impacts on the tumour actions on surrounding bone tissue. Lastly, we detail therapies for bone metastases. Due to poor prognosis for patients, the strategies mainly aim at reducing the impact of skeletal-related events on patients' quality of life. However, recent advances have led to a better understanding of molecular mechanisms underlying bone metastases progression, and therefore of novel therapeutic targets.

In vivo distribution of zoledronic acid in a bisphosphonate-metal complex-based nanoparticle formulation synthesized by a reverse microemulsion method

Bisphosphonates are used to treat bone diseases such as osteoporosis and cancer-induced bone pain and fractures. It is thought that modifying the pharmacokinetics and biodistribution profiles of bisphosphonates (i.e. rapid renal clearance and extensive bone absorption) will not only reduce their side effects, but also expand their clinical applications to extraskeletal tissues. In the present work, using zoledronic acid (Zol) and calcium as model bisphosphonate and metal molecules, respectively, we prepared DOPA (an anionic lipid)-coated spherical Zol-Ca nanocomposites (Zol-Ca@DOPA) and developed Zol-nanoparticle formulations (i.e. Zol-Ca@bi-lipid NPs) based on the nanocomposites. The influence of the inputted weight ratio of Zol-Ca@DOPA to DSPE-PEG_2k on the properties (e.g. size, size distribution, loading efficiency, encapsulation efficiency, zeta potential, and polydispersity) of Zol-Ca@bi-lipid NPs was investigated, and a type of Zol-Ca@bi-lipid NPs with size around 25nm was selected for further studies. In a mouse model, the Zol-Ca@bi-lipid NPs significantly reduced the bone distribution of Zol, increased the blood circulating time of Zol, and altered the distribution of Zol in major organs, as compared to free Zol. It is expected that similar nanoparticles prepared with bisphosphonate-metal complexes can be explored to expand the applications to bisphosphonates in extraskeletal tissues.

Fracture Burden: What Two and a Half Decades of Dubbo Osteoporosis Epidemiology Study Data Reveal About Clinical Outcomes of Osteoporosis

PURPOSE OF THE REVIEW

This review aims to highlight important clinical findings from the over 25 year-long Dubbo Osteoporosis Epidemiology Study particularly focusing on outcomes post fracture.

RECENT FINDINGS

Every low trauma fracture in the elderly is associated with an increased risk of a subsequent fracture, with a higher risk in men than women. All major or proximal fractures and even minor fractures in the very elderly or minor fractures that are then followed by re-fracture are associated with premature mortality, greatest in the first 5 years post fracture. Having a subsequent fracture further increases this high mortality risk, but if an individual survives the high risk period, their risk returns to that of the background population. Non-hip non-vertebral fractures account for a significant proportion of the premature mortality. Despite an improvement in overall health and population mortality over the years, excess mortality post fracture has not changed in the last 2 decades. All low trauma, fractures in the elderly herald a high risk of poor outcomes, particularly in the first few years post fracture. Early intervention should be initiated.

Treatment landscape of metastatic prostate cancer: the role of radium-223

The landscape of metastatic prostate cancer has changed recently with the availability of six new molecules showing an overall survival benefit. The development of compounds able to decrease the rate of complications from bone metastasis has also led to improvements in overall morbidity associated with this disease. In this paper, we briefly review the currently available drugs indicated in the treatment of metastatic prostate cancer, focusing on the place of the radiopharmaceutical agent radium-223 and its very unique mechanism of action and safety profile.

[Decrease in toxicity and therapeutic effect of zoledronic acid in combination therapy with different antioxidant extracts]

BACKGROUND

Zoledronic acid is used in the treatment of cancer-related diseases, although its use has been associated with avascular osteonecrosis.

AIMS

To determine the possible protective effect of a range of antioxidant substances against the inhibition of human prostate epithelial cell growth (PNT2) and transgenic adenocarcinoma mouse prostate tumour cells (TRAMP-C1), in treatments combining zoledronic acid and ionising radiation (IR).

MATERIAL AND METHOD

Cell survival is studied via cell viability assays (MTT) for 2 cell lines in isolated and combined treatments with zoledronic acid and/or IR, as well as the effect of adding 3 antioxidant substances.

RESULTS

Zoledronic acid displays a significant cytotoxic effect over PNT2 and TRAMP-C1 cells (P<.001). The administration of antioxidants together with the zoledronic acid shows a protective effect for normal prostate cells, yet not so for prostate tumour cells. However, the administration of rosmarinic acid and apigenin in treatments combined with zoledronic acid provides a protective effect from the harmful effects of applying ionizing radiation, not only for normal PNT2 cells, but also for tumour cells.

CONCLUSION

The use of antioxidant substances decreases the cytotoxic effect of zoledronic acid over non-tumour cells, and as such could be used in benign diseases. Furthermore, in the combined treatment using ionising radiation, these antioxidants also produced a protective effect in tumour cells, thus reducing the therapeutic effect sought by combining the treatment with radiation.

Dosing of zoledronic acid with its anti-tumor effects in breast cancer

Bisphosphonates have played an important role in the treatment of breast cancer, mainly in patients with bone metastasis, by reducing the risk of fracture, spinal cord compression, and hypercalcemia. Zoledronic acid, the most frequently used intravenous agent, has been traditionally administered on a monthly dosing schedule. Preclinical studies have demonstrated that zoledronic acid can inhibit angiogenesis, invasion, and adhesion of tumor cells. Several clinical studies of different timings and schedules of zoledronic acid therapy have demonstrated its anti-tumor effects, as well as its protective effect on bone health, in postmenopausal women during adjuvant breast cancer therapy. In general, early initiation of zoledronic acid, concomitantly with adjuvant therapy, has been found to be most beneficial. However, questions remain over the most effective schedule of treatment and relative potency of zoledronic acid. Therefore, we review the existing clinical studies to examine the influence of dosing of zoledronic acid therapy on clinical outcomes in patients with breast cancer.

Minimally invasive treatment of a painful osteolytic lumbar lesion secondary to epithelioid hemangioendothelioma

Study Design Case report. Objective Multifocal epithelioid hemangioendothelioma (EHE) of the spine is a rare disorder. We describe a novel, multimodal treatment of a painful osteolytic lumbar lesion secondary to EHE. The minimally invasive treatment results in an excellent patient outcome with decreased morbidity compared to traditional techniques. Methods A previously healthy young adult presented with a painful osteolytic lesion at the L2 vertebrae. Imaging revealed multifocal spinal lesions consistent with a history of EHE. Core needle biopsy confirmed the diagnosis. Preoperative cryoablation of L2 was followed by a staged surgery, which included a partial L2 corpectomy, tumor resection, bone grafting, and vertebral reconstruction using a minimally invasive technique. This treatment was followed by prolonged therapy with interferon and bisphosphonate. Results At 3.5 years' follow-up, the patient has maintained his vertebral body height, has not required a fusion, and has had no recurrence of disease. Conclusion Multimodal treatment consisting of tumor cryoablation, partial corpectomy, allograft reconstruction of the vertebrae, and adjuvant interferon and bisphosphonate can result in good outcomes for well-contained EHE tumors of the spine.

2,6-Dimethylphenol derived H-phosphonate and α-hydroxyphosphonate: facile synthesis, crystal chemistry, supramolecular association and metal complexation

A H-phosphonate and an α-hydroxyarylphosphonate with active P–H and P–OH groups have been synthesized from 2,6-dimethylphenol and their aggregation behavior has been investigated.

Biomimetic apatite-coated porous PVA scaffolds promote the growth of breast cancer cells

Recapitulating the native environment of bone tissue is essential to develop in vitro models of breast cancer bone metastasis. The bone is a composite material consisting of organic matrix and inorganic mineral phase, primarily hydroxyapatite. In this study, we report the mineralization of porous poly vinyl alcohol (PVA) scaffolds upon incubation in modified Hanks' Balanced Salt Solution (HBSS) for 14 days. Scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction analysis revealed that the deposited minerals have composition similar to hydroxyapatite. The study demonstrated that the rate of nucleation and growth of minerals was faster on surfaces of less porous scaffolds. However, upon prolonged incubation, formation of mineral layer was observed on the surface of all the scaffolds. In addition, the study also demonstrated that 3D mineralization only occurred for scaffolds with highly interconnected porous networks. The mineralization of the scaffolds promoted the adsorption of serum proteins and consequently, the adhesion and proliferation of breast cancer cells.

Zoledronic acid and irradiation in oral squamous cell carcinoma

OBJECTIVE

This in vitro study evaluated cytotoxicity and cell migration effects of zoledronic acid and irradiation upon oral squamous cell carcinoma.

MATERIALS AND METHODS

Zoledronic acid was administrated at doses of 10, 25, 50, and 100 μM to PE/CA-PJ15 oral squamous cell carcinoma cultures, irradiated with different doses (0, 5, 15, and 30 Gy), followed by evaluation of the effects on cell viability. Cell migration capacity was studied after 24- and 72-h incubation.

RESULTS

At 24 h, the 100 μM concentration of zoledronic acid combined with 15 Gy irradiation caused the greatest decrease in cell viability. At 72 h, statistically significant decreases in cell viability were found with all concentrations of zoledronic acid with or without irradiation: 0 Gy (P < 0.001), 5 Gy (P < 0.001), 15 Gy (P < 0.001), and 30 Gy (P < 0.001). 50 μM and 100 μM doses of zoledronic acid combined with 5 Gy irradiation yielded the greatest decrease in cell migration capacity.

CONCLUSIONS

Zoledronic acid increases cytotoxic activity in the PE/CA-PJ15 cell line and reduces cell migration capacity. These findings suggest that combination therapy using biphosphates and radiation may offer a promising therapy.

Primary diffuse large B-cell lymphoma of the bone: bendamustine and rituximab are able to overcome resistant disease

Primary bone lymphoma (PBL) is a rare disease for which specific therapeutic guidelines have not yet been established. Due to common appearance in the elderly and recurring relapses, new treatments are required. We report the case of multiple relapsed aggressive PBL effectively treated using Bendamustine and Rituximab. A 78-year-old male patient presented with a painful mass in the left arm. Computed tomography (CT) showed a pathological tissue in the humerus diaphysis infiltrating the muscle, confirmed by positron emission tomography (PET) scan. Indeed, PET excluded pathological local lymph node involvement. Biopsy of the humerus revealed the presence of diffuse large B cell lymphoma. Recommended treatments for PBL were used, but relapses after an initial complete response occurred. Following the positive experience of Vacirca et al. the patient underwent Bendamustin 90 mg/mq gg1-2 q28 plus Rituximab 375 mg/mq q28 (BR). Herein we report the first experience of BR combination in PBL and it proved to be an efficacious and safe salvage therapy in relapsed/refractory PBL.

Therapeutic strategies for treating osteolytic bone metastases

The recent progress in oncologic management of patients with localized cancer or metastatic disease has permitted a significant improvement in life expectancy. Nevertheless, bone metastases and their consequent skeletal-related events (SREs) are still associated with unfavorable prognosis and greatly affect quality of life. Global management of these bone metastases includes traditional local approaches (surgery, radiotherapy, etc.) and systemic administration of chemotherapeutic agents. This review focuses on treatments specific for bone metastases and, in particular, on inhibitors of bone resorption that are effective for preventing and delaying the development of SREs.

A Case of Lung Adenocarcinoma with Postoperative Recurrence of Multiple Bone Metastases that Showed a Gradual Complete Response to Combined Administration of Erlotinib and Zoledronic Acid

We describe a case of lung adenocarcinoma with multiple postoperative bone metastases that showed a gradual but complete response to combined administration of erlotinib and zoledronic acid. A 76-year-old man with moderately differentiated adenocarcinoma underwent a radical left upper lobectomy and mediastinal lymph node dissection. Three and a half years after the operation, serum carcinoembryonic antigen (CEA) was elevated and 18F-fluorodeoxyglucose positron emission tomography (18FDG-PET) revealed multiple bone metastases. Pretreatment evaluation of EGFR mutations in the resected primary adenocarcinoma specimen showed an L858R mutation in exon 21. Gefitinib was started as first-line treatment. However, evaluation 1 month after administration revealed progressive disease. Erlotinib was started as second-line treatment, and evaluation 1 month after administration revealed that the disease was stable. Administration of zoledronic acid was then begun with continuation of erlotinib. After 2 courses of zoledronic acid, the serum CEA level had not changed but the maximum standardized uptake values of each region uniformly decreased. Furthermore, the uptake of 18FDG completely disappeared after 6 courses. Subsequently, the serum CEA level continued to decrease and the disappearance of 18FDG uptake was confirmed after 10 courses (12 months after initiation of erlotinib administration). Our results suggest that the combined administration of both drugs is effective against bone metastases.

Bisphosphonate therapy for unresectable symptomatic benign bone tumors: a long-term prospective study of tolerance and efficacy

OBJECTIVES

To evaluate the long-term tolerance of bisphosphonates proposed as an alternative therapeutic option for symptomatic unresectable benign bone tumors and to evaluate the long-term efficacy of this treatment.

METHODS

From March 2007 to March 2011, patients with unresectable symptomatic benign bone tumors were consecutively included in this institutional review board-approved study and treated with bisphosphonates. Prospectively long-term follow-up is reported. The study endpoints were to describe the long-term tolerance, the clinical evolution of pain for each patient and the radiological success defined as a complete disappearance of inflammation and ossification of the bone lesion. All complications and side effects were recorded.

RESULTS

Eight patients (mean age 16 years; range 7-42) with various tumor subtypes were included: aneurysmal bone cysts (N=5), Langerhans cell histiocytosis (N=1), osteoblastoma (N=1), and a giant cell tumor (N=1). Tumors were located in cervical (N=4) or thoracic (N=1) vertebrae, femoral shaft (N=1), acetabulum (N=1) and sacrum (N=1). Mean number of bisphosphonate cycles was 3 (range: 1-6) over a median period of 10 months. The median clinical and imaging follow-up period was 21 months (6 to 63 months). No severe complications due to treatment or lesion recurrence were reported. Pain disappeared within 6 weeks of the first cycle for all but one patient. Ossification of the bone lesion was observed for all patients but one, complete for two and partial for the five others.

CONCLUSIONS

Bisphosphonates appear to be an effective option without adverse effects for the non-operative management of symptomatic benign bone tumors.

Low doses amino-bisphosphonates stimulate keratinocytes growth inactivating glucocorticoid receptor

Amino-bisphosphonates (N-BPs) have a wide range of clinical applications to treat bone diseases. Their activity lowered farnesyl pyrophosphate (FPP) endogenous levels by inhibiting FPP synthase. In epithelial cells it has been demonstrated that FPP reduces both cell proliferation and migration activting glucocorticoid receptor. In this study two N-BPs (zoledronate and neridronate) used at low concentrations (100 nM to 10 μM) are able to stimulate human keratinocytes proliferation reducing glucocorticoid receptor activation.

Exposure to bisphosphonates and risk of common non-gastrointestinal cancers: series of nested case-control studies using two primary-care databases

BACKGROUND

Bisphosphonates are the most commonly prescribed osteoporosis drugs but long-term effects are unclear, although antitumour properties are known from preclinical studies.

METHODS

Nested case-control studies were conducted to investigate bisphosphonate use and risks of common non-gastrointestinal cancers (breast, prostate, lung, bladder, melanoma, ovarian, pancreas, uterus and cervical). Patients 50 years and older, diagnosed with primary cancers between 1997 and 2011, were matched to five controls using the UK practice-based QResearch and Clinical Practice Research Datalink (CPRD) databases. The databases were analysed separately and the results combined.

RESULTS

A total of 91 556 and 88 845 cases were identified from QResearch and CPRD, respectively. Bisphosphonate use was associated with reduced risks of breast (odds ratio (OR): 0.92, 95% confidence interval (CI): 0.87-0.97), prostate (OR: 0.87, 95% CI: 0.79-0.96) and pancreatic (OR: 0.79, 95% CI: 0.68-0.93) cancers in the combined analyses, but no significant trends with duration. For alendronate, reduced risk associations were found for prostate cancer in the QResearch (OR: 0.81, 95% CI: 0.70-0.93) and combined (OR: 0.84, 95% CI: 0.75-0.93) analyses (trend with duration P-values 0.009 and 0.001). There were no significant associations from any of the other analyses.

CONCLUSION

In this series of large population-based case-control studies, bisphosphonate use was not associated with increased risks for any common non-gastrointestinal cancers.

Bone targeted therapies in metastatic castration-resistant prostate cancer

Prostate cancer is the most common male cancer. About 90% of metastatic patients will develop bone metastases. Bone disease is responsible of pain, deterioration of quality of life and serious bone complications. Proliferation of prostate cancer cells in the bone marrow induces osteoclast activation and osteolysis. Targeting the bone microenvironment reduces morbidity. Relevant preclinical and clinical studies of bone-targeted therapies in castration-resistant prostate cancer were identified in PubMed and clinical trial databases. Different drugs are available or in development that target bone resorption (bisphosphonates, RANK ligand inhibitors), bone formation (endothelin 1 inhibitors), cancer cell migration (SRC-family kinase inhibitors, vascular endothelial growth factor-MET inhibitors), and survival (radiopharmaceuticals). In phase III trials, zoledronic acid, denosumab, and radium-223 were shown to significantly delay skeletal-related events. Radium-223 was also shown to improve overall survival. Biomarkers of bone resorption (urinary N-telopeptide) and bone making (alkaline phosphatase) have an independent prognostic impact. Targeting the bone microenvironment is an important component of castration-resistant prostate cancer management to reduce bone complications and improve overall survival. Biomarkers of bone turnover have an independent prognostic impact.

Advances in prevention and treatment of bone metastases in prostate cancer. Role of RANK/RANKL inhibition

BACKGROUND

Bone metastases are a common complication of prostate cancer, so treatment and prevention are essential to slow the progression of the disease and the occurrence of skeletal related events (SREs), which have devastating consequences for the quality of life of patients.

SUMMARY OF EVIDENCE

Bone metastases are characterized by increased bone turnover and altered balance between osteogenesis and osteolysis, with activation of the RANK and its ligand (RANKL). In patients with metastatic prostate cancer, bisphosphonates have been the bone-targeted agents most commonly used to date. Zoledronic acid has demonstrated efficacy in the reduction and delay of SREs in patients with bone metastases. Denosumab, a RANKL inhibitor, has been demonstrated to be superior to zoledronic acid in the prevention of SREs in castration-resistant prostate cancer (CRPC). Both agents are being considered, along with other new bone-targeted agents, for the prevention of bone metastases in patients with nonmetastatic CRPC, where denosumab has already demonstrated superiority over placebo.

CONCLUSIONS

Denosumab and zoledronic acid prevent SREs in patients with prostate cancer and bone metastases. Denosumab also has a potential role in delaying bone metastases in nonmetastatic patients. Advances in the treatment of CRPC include an increasing focus on prevention of the progression of bone disease.

Possible survival benefits from zoledronic acid treatment in patients with bone metastases from solid tumours and poor prognostic features-An exploratory analysis of placebo-controlled trials

Background

Zoledronic acid (ZOL) is an important component of therapy for patients with metastatic bone disease (MBD) to reduce the risk of skeletal-related events (SREs). We evaluated overall survival (OS) in patients with MBD secondary to solid tumours included in placebocontrolled ZOL trials.

Patients and methods

Exploratory analyses were performed using databases from three randomised trials of ZOL versus placebo. 1126 patients (ZOL, n=731; placebo, n=395) with complete baseline data for 18 predefined parameters were evaluated for OS. Relative risks (RRs) with 95% confidence intervals were assessed using stratified and adjusted Cox regression models. Baseline covariates defining patient populations with significantly different effects of ZOL treatment on OS (identified by stepwise backward elimination) were included in multivariate models.

Results

Although OS was similar between the overall treatment groups, ZOL significantly improved OS in the subset of patients (n=423; 38%) with elevated baseline NTX (≥100 nmol/mmol creatinine; RR, 0.692; P=.0028). Notably, this effect was independent of SRE prevention. Additional covariates associated with OS benefits with ZOL (e.g., low albumin, SRE history, elevated lactate dehydrogenase, shorter cancer duration) were characteristic of advanced disease.

Conclusion

These exploratory analyses suggest a beneficial effect of ZOL on OS in patients with highly aggressive or advanced MBD.

Cisplatin in combination with zoledronic acid: a synergistic effect in triple-negative breast cancer cell lines

Zoledronic acid (ZA) is the most widely used bisphos-phonate to treat cancer-induced bone disease. There is evidence that bisphosphonates have direct antitumor activity and that their combination with anticancer agents can significantly enhance the effect of treatment. We evaluated whether the combination of ZA with different platinum compounds exerts a synergistic effect in breast cancer cell lines and we investigated the mechanisms of action involved. This study was performed on four breast cancer cell lines, MCF-7, SKBR3, MDA-MB-231 and BRC-230, and confirmed on a primary culture obtained from a breast cancer bone metastasis specimen. ZA (50 µM) was administered for 72 h alone or in combination with cisplatin (Cis) or carboplatin. Drug-induced growth inhibition was detected by sulforhodamine B assay, apoptosis and cell cycle regulation were detected by flow cytometry, and protein expression was evaluated by western blot analysis. MCF-7 and SKBR3 showed very low sensitivity to the three drugs tested. The ZA + Cis combination exerted a high antitumor activity in the two triple-negative lines MDA-MB-231 and BRC-230. An important synergistic effect was obtained in MDA-MB-231 and an additive effect was observed in BRC-230. The p21, pMAPK and m-TOR pathways were regulated by this combined treatment, particularly at lower Cis doses. Carboplatin did not show antitumor activity either alone or in combination with ZA. In conclusion, the potential novel treatment schedule identified for triple-negative breast cancer could prove beneficial in view of the limited therapeutic options available for patients and also since the synergism with ZA would enable lower Cis doses to be used, thus reducing toxicity. Although further research in a clinical setting is warranted, our results on cell lines has been confirmed on a human primary bone metastasis culture.

Exposure to bisphosphonates and risk of gastrointestinal cancers: series of nested case-control studies with QResearch and CPRD data

OBJECTIVE

To investigate the association between use of bisphosphonates estimated from prescription information and risk of gastrointestinal cancers.

DESIGN

Series of nested case-control studies.

SETTING

General practices in the United Kingdom contributing to the QResearch primary care database (660) and the Clinical Practice Research Datalink (CPRD) (643).

PARTICIPANTS

Patients aged ≥ 50 with a diagnosis of a primary gastrointestinal cancer in 1997-2011, each matched with up to five controls by age, sex, practice, and calendar year.

MAIN OUTCOME MEASURES

Odds ratios for incident gastrointestinal cancers (colorectal, oesophageal, gastric) and use of bisphosphonates, adjusted for smoking status, ethnicity, comorbidities, and use of other drugs.

RESULTS

20,106 and 19,035 cases of colorectal cancer cases, 5364 and 5135 cases of oesophageal cancer cases, and 3155 and 3157 cases of gastric cancer were identified from QResearch and CPRD, respectively. Overall bisphosphonate use (at least one prescription) was not associated with risk of colorectal, oesophageal, or gastric cancers in either database. Adjusted odds ratios (95% confidence interval) for QResearch and CPRD were 0.97 (0.79 to 1.18) and 1.18 (0.97 to 1.43) for oesophageal cancer; 1.12 (0.87 to 1.44) and 0.79 (0.62 to 1.01) for gastric cancer; and 1.03 (0.94 to 1.14) and 1.10 (1.00 to 1.22) for colorectal cancer. Additional analyses showed no difference between types of bisphosphonate for risk of oesophageal and colorectal cancers. For gastric cancer, alendronate use was associated with an increased risk (1.47, 1.11 to 1.95; P=0.008), but only in data from the QResearch database and without any association with duration and with no definitive confirmation from sensitivity analysis.

CONCLUSIONS

In this series of population based case-control studies in two large primary care databases, exposure to bisphosphonates was not associated with an increased risk of common gastrointestinal cancers.

Inhibition of breast cancer cell proliferation in repeated and non-repeated treatment with zoledronic acid

Background

Zoledronic acid is used to treat bone metastases and has been shown to reduce skeletal-related events and exert antitumor activity. The present in vitro study investigates the mechanism of action of Zoledronic Acid on breast cancer cell lines with different hormonal and HER2 patterns. Furthermore, we investigated the efficacy of repeated versus non-repeated treatments.

Methods

The study was performed on 4 breast cancer cell lines (BRC-230, SkBr3, MCF-7 and MDA-MB-231). Non-repeated treatment (single exposure of 168 hrs’ duration) with zoledronic acid was compared with repeated treatment (separate exposures, each of 48 hrs’ duration, for a total of 168 hrs) at different dosages. A dose–response profile was generated using sulforhodamine B assay. Apoptosis was evaluated by TUNEL assay and biomolecular characteristics were analyzed by western blot.

Results

Zoledronic acid produced a dose-dependent inhibition of proliferation in all cell lines. Anti-proliferative activity was enhanced with the repeated treatment, proving to be statistically significant in the triple-negative lines. In these lines repeated treatment showed a cytocidal effect, with apoptotic cell death caused by caspase 3, 8 and 9 activation and decreased RAS and pMAPK expression. Apoptosis was not observed in estrogen receptor-positive line: p21 overexpression suggested a slowing down of cell cycle. A decrease in RAS and pMAPK expression was seen in HER2-overexpressing line after treatment.

Conclusions

The study suggests that zoledronic acid has an antitumor activity in breast cancer cell lines. Its mechanism of action involves the decrease of RAS and RHO, as in osteoclasts. Repeated treatment enhances antitumor activity compared to non-repeated treatment. Repeated treatment has a killing effect on triple-negative lines due to apoptosis activation. Further research is warranted especially in the treatment of triple-negative breast cancer.

Alendronate-conjugated amphiphilic hyperbranched polymer based on Boltorn H40 and poly(ethylene glycol) for bone-targeted drug delivery

A novel type of alendronate(ALE)-conjugated amphiphilic hyperbranched copolymer based on a hydrophobic hyperbranched Boltorn H40 (H40) core with ALE targeting moiety and many hydrophilic poly(ethylene glycol) (PEG) arms was synthesized as a carrier for bone-targeted drug delivery. The star copolymer H40-star-PEG/ALE was characterized using nuclear magnetic resonance (NMR), Fourier transformed infrared spectroscopy (FTIR), and gel permeation chromatography (GPC) analysis. Benefiting from its highly branched structure, H40-star-PEG/ALE could form micelles in aqueous solution, which was confirmed by transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. The cytotoxicity and hemolysis of the H40-star-PEG/ALE micelles were evaluated via methylthiazoletetrazolium (MTT) assay against NIH/3T3 normal cells and red blood cell (RBC) lysis assay, respectively. As a model anticancer drug, doxorubicin (DOX) was encapsulated into the H40-star-PEG/ALE micelles. The anticancer activity of DOX-loaded micelles was evaluated by MTT assay against an HN-6 human head and neck carcinoma cell line. The strong affinity of H40-star-PEG/ALE micelles to bone was confirmed by the hydroxyapatite (HA) binding assay. These results indicate that the H40-star-PEG/ALE micelles are highly promising bone-targeted drug carriers for skeletal metastases.

Exposure to oral bisphosphonates and risk of cancer

Recently, oral bisphosphonate use has increased markedly in the United States and elsewhere. Little is known about cancer risks associated with these drugs. A few studies have observed associations between bisphosphonates and the risk of breast, colorectal and esophageal cancer. However, the risk of all cancer and the risk of other cancers have not been investigated. In our study, we examined the risk of all cancer and site specific cancers in individuals taking bisphosphonates. Data were extracted from the UK General Practice Research Database to compare site-specific cancer incidence in a cohort of oral bisphosphonate users and a control cohort. Hazard ratios (HRs) were calculated using Cox regression modeling. The bisphosphonate and control cohort contained 41,826 participants (mean age 70, 81% female). Overall, the bisphosphonate cohort compared with the control cohort had a reduced risk of all cancer after any bisphosphonate usage [HR=0.87, 95% confidence interval (CI) 0.82, 0.92]. In the bisphosphonate cohort, compared with the control cohort, there was no evidence of a difference in the risk of lung (HR=1.03, 95% CI 0.88, 1.20) or prostate cancer (HR=0.86, 95% CI 0.67, 1.09) but breast (HR=0.71, 95% CI 0.62, 0.81) and colorectal cancer (HR=0.74, 95% CI, 0.60-0.91) were both reduced. Our findings indicate that bisphosphonates do not appear to increase cancer risk. Although reductions in breast and colorectal cancer incidence were observed in bisphosphonate users it is unclear, particularly for breast cancer, to what extent confounding by low bone density may explain the association.

Oral alendronate use and risk of cancer in postmenopausal women with osteoporosis: A nationwide study

The association between use of oral bisphosphonates and cancer development in elderly women is still uncertain, and previous studies have shown controversial results. We used a nationwide, population-based database to explore the relationship between the use of alendronate, an oral bisphosphonate agent used for the treatment of osteoporosis, and the risk of all malignancies in women with osteoporosis and age over 55 years. In the study group, we included 6906 women with osteoporosis (age, mean ± SD, 73.4 ± 8.4 years) taking oral alendronate, who were selected from a 1,000,000 sample cohort dataset collected between January 1998 and December 2009. Another 20,697 age- and comorbidity-matched women (73.5 ± 8.4 years) without bisphosphonates treatment were included in the control group. No subjects had any history of being diagnosed with cancer before inclusion. We used a log-rank test to analyze the differences in accumulated cancer-free survival rates between these two groups. A Cox proportional-hazard model, adjusted for confounding factors, was used to evaluate the association between alendronate use and the development of all cancer events in postmenopausal women with osteoporosis. During the mean follow-up period of 4.8 years, 821 patients from the study group and 2646 patients from the control group had new cancers. There was no significant difference in cancer incidence between alendronate users and controls (11.9% versus 12.8%, p = 0.054). The person-year incidence of newly-developed cancer in alendronate users and controls was 28.0 and 29.4 per 1000 person-years, respectively. Alendronate use was not associated with increased risk of cancer development in women with osteoporosis (adjusted hazard ratio, 1.05; 95% confidence interval [CI], 0.97-1.13; p = 0.237). However, due to the limited study size and underpowered results, further larger prospective studies or meta-analysis are suggested to further confirm our findings.

Zoledronic acid and radiation: toxicity, synergy or radiosensitization?

INTRODUCTION

Zoledronic acid (Z) is a bisphosphonate used in hypercalcaemia-related cancer, in complications for bone metastasis and in postmenopausal osteoporosis and it has been related to osteoradionecrosis, especially when associated with radiation to the head and neck structures.

OBJECTIVES

To determine the radiosensitization capacity of zoledronic acid in the combined treatment with ionizing radiation (IR) by evaluating its genotoxic and cytotoxic capacities in non-tumoral cells.

MATERIALS AND METHODS

The genotoxic effect of Z was studied by means of the micronucleus test in cytokinesis-blocked cells of human lymphocytes irradiated before and after a 2 Gy irradiation, while the cytotoxic effect was studied by a cell viability test in the PNT2 cell line before and after exposure to different X-ray doses (0-20 Gy) in four groups (Z alone, radiation alone, Z + IR and IR + Z).

RESULTS

A dose-dependent and time-dependent cytotoxic effect of Z and IR on PNT2 cells in vitro (p > 0.001) was demonstrated. With the concentrations recommended for humans, the combined treatment had a more pronounced effect than individual treatments (p < 0.001). The effect was synergic (CI < 1), increasing the Z enhancement ratio (2.6) and sensitization factor (56 %); the effect of Z was always greater after IR exposure. In the genotoxic effect, only the administration of Z after irradiation (IR + Z) increased chromosome damage (p < 0.001) and the sensibilization factor (35.7 %).

CONCLUSION

High concentrations of Z are toxic, but the concentrations recommended for clinical practice in humans give it the characteristics of a radiosensitization agent, whose effect is even greater when administered after IR.

Remarkable regression of an osteolytic lesion of large cell lung cancer treated with zoledronic Acid: a case report

Zoledronic acid suppresses osteoclastic changes and reduces the risk of cancer-induced skeletal-related events. Moreover, it has been reported to have antitumor effects. The authors here present a case of a male patient with large cell lung cancer who had an osteolytic lesion in the thoracic vertebrae. The cancer was moderately sensitive to radiation therapy but barely sensitive to chemotherapy with cytotoxic agents. However, it was markedly regressed after zoledronic acid monotherapy, and the patient's symptoms almost disappeared. This remarkable response of large cell lung cancer to zoledronic acid monotherapy is rare.

Activation of BK(Ca) channels in zoledronic acid-induced apoptosis of MDA-MB-231 breast cancer cells

BACKGROUND

Zoledronic acid, one of the most potent nitrogen-containing biphosphonates, has been demonstrated to have direct anti-tumor and anti-metastatic properties in breast cancer in vitro and in vivo. In particular, tumor-cell apoptosis has been recognized to play an important role in the treatment of metastatic breast cancer with zoledronic acid. However, the precise mechanisms remain less clear. In the present study, we investigated the specific role of large conductance Ca(2+)-activated potassium (BK(Ca)) channel in zoledronic acid-induced apoptosis of estrogen receptor (ER)-negative MDA-MB-231 breast cancer cells.

METHODOLOGY/PRINCIPAL FINDINGS

The action of zoledronic acid on BK(Ca) channel was investigated by whole-cell and cell-attached patch clamp techniques. Cell apoptosis was assessed with immunocytochemistry, analysis of fragmented DNA by agarose gel electrophoresis, and flow cytometry assays. Cell proliferation was investigated by MTT test and immunocytochemistry. In addition, such findings were further confirmed with human embryonic kidney 293 (HEK293) cells which were transfected with functional BK(Ca) α-subunit (hSloα). Our results clearly indicated that zoledronic acid directly increased the activities of BK(Ca) channels, and then activation of BK(Ca) channel by zoledronic acid contributed to induce apoptosis in MDA-MB-231 cells. The possible mechanisms were associated with the elevated level of intracellular Ca(2+) and a concomitant depolarization of mitochondrial membrane potential (Δψm) in MDA-MB-231 cells.

CONCLUSIONS

Activation of BK(Ca) channel was here shown to be a novel molecular pathway involved in zoledronic acid-induced apoptosis of MDA-MB-231 cells in vitro.