Antitumor effects of bisphosphonates

Synthesis, characterization and osteoconductivity properties of bone fillers based on alendronate-loaded poly(ε-caprolactone)/hydroxyapatite microspheres

A superior drug controlled release system capable of achieving efficient osteogenesis is in imperative demand because of limited bone substitute tissue for the treatment of bone defect. In the present study, we investigated the potential of using poly(ε-caprolactone)-hydroxyapatite (PCL-HA) composite microspheres as an injectable bone repair vehicle by controlled release of alendronate (AL), a medicine that belongs to the bisphosphonates family. The PCL/HA-AL microspheres were prepared with solid/oil/water emulsion technique, which included two processes: (1) AL was loaded on the hydroxyapatite nanoparticles; (2) the HA-AL complex was built in the PCL matrix. The spherical PCL/HA-AL microspheres were characterized with its significantly improved encapsulation efficiency of hydrophilic AL and better sustained release. Human bone mesenchymal stem cells (hMSCs) were cultured on the surface of these microspheres and exhibited high proliferative profile. Specifically, in osteogenic medium, hMSCs on the surface of PCL/HA-AL microspheres displayed superior osteogenic differentiation which was verified by alkaline phosphatase activity assay. In conclusion, by presenting strong osteogenic commitment of hMSCs in vitro, the PCL/HA-AL microspheres have the potential to be used as an injectable vehicle for local therapy of bone defect.

Use of bisphosphonates and reduced risk of colorectal cancer

PURPOSE

Bisphosphonates are commonly used for the treatment of osteoporosis and bone metastases caused by breast cancer and were recently reported to be associated with a reduced risk of breast cancer, possibly acting through the mevalonate pathway, but their association with risk of other cancers is unknown.

PATIENTS AND METHODS

The Molecular Epidemiology of Colorectal Cancer study is a population-based, case-control study in northern Israel of patients with colorectal cancer and age-, sex-, clinic-, and ethnic group-matched controls. Long-term use of bisphosphonates before diagnosis was assessed in a subset of 933 pairs of postmenopausal female patients and controls, enrolled in Clalit Health Services, using computerized pharmacy records.

RESULTS

The use of bisphosphonates for more than 1 year before diagnosis, but not for less than 1 year, was associated with a significantly reduced relative risk (RR) of colorectal cancer (RR, 0.50; 95% CI, 0.35 to 0.71). This association remained statistically significant after adjustment in a model for vegetable consumption, sports activity, family history of colorectal cancer, body mass index, and use of low-dose aspirin, statins, vitamin D, and postmenopausal hormones (RR, 0.41; 95% CI, 0.25 to 0.67). Concomitant use of bisphosphonates and statins did not further reduce the risk.

CONCLUSION

The use of oral bisphosphonates for more than 1 year was associated with a 59% relative reduction in the risk of colorectal cancer, similar to the recently reported association of this drug class with reduction in breast cancer risk.

Use of bisphosphonates and reduced risk of colorectal cancer

PURPOSE

Bisphosphonates are commonly used for the treatment of osteoporosis and bone metastases caused by breast cancer and were recently reported to be associated with a reduced risk of breast cancer, possibly acting through the mevalonate pathway, but their association with risk of other cancers is unknown.

PATIENTS AND METHODS

The Molecular Epidemiology of Colorectal Cancer study is a population-based, case-control study in northern Israel of patients with colorectal cancer and age-, sex-, clinic-, and ethnic group-matched controls. Long-term use of bisphosphonates before diagnosis was assessed in a subset of 933 pairs of postmenopausal female patients and controls, enrolled in Clalit Health Services, using computerized pharmacy records.

RESULTS

The use of bisphosphonates for more than 1 year before diagnosis, but not for less than 1 year, was associated with a significantly reduced relative risk (RR) of colorectal cancer (RR, 0.50; 95% CI, 0.35 to 0.71). This association remained statistically significant after adjustment in a model for vegetable consumption, sports activity, family history of colorectal cancer, body mass index, and use of low-dose aspirin, statins, vitamin D, and postmenopausal hormones (RR, 0.41; 95% CI, 0.25 to 0.67). Concomitant use of bisphosphonates and statins did not further reduce the risk.

CONCLUSION

The use of oral bisphosphonates for more than 1 year was associated with a 59% relative reduction in the risk of colorectal cancer, similar to the recently reported association of this drug class with reduction in breast cancer risk.

Serum C-telopeptide levels predict the incidence of skeletal-related events in cancer patients with secondary bone metastases

INTRODUCTION

We evaluated serum C-telopeptides (CTX) to see whether they may be useful as predictive markers for disease progression in cancer patients with bone metastases who are being treated with zoledronic acid (ZA).

PATIENTS AND METHODS

This was a prospective, nonrandomised study in which 26 patients with solid tumours and confirmed bone metastases were treated with ZA (4 mg every 3-4 weeks) for 24 months or until a skeletal-related event (SRE) was observed. Serum CTX levels were determined at baseline and 6, 12, 18 and 24 months after study initiation. SRE were evaluated using bone scintigraphy.

RESULTS

Study participants had prostate (50%), breast (31%), lung (11%) or bladder (8%) tumours. Mean age was 69 (range 52-84) years, and 65% men. At baseline, overall mean CTX levels were 562.47 ± 305.17 pg/dl. Patients who showed disease progression during the study period showed significantly higher CTX levels at baseline and after 18 months of ZA treatment than patients who did not progress (p = 0.040 and p = 0.006, respectively). Patients with ≥ 5 bone metastases at diagnosis had significantly higher CTX levels after 18 months of ZA treatment than patients with < 5 bone metastasis (p = 0.001). Similarly, at 12 and 18 months, patients without SRE had significantly lower CTX levels than patients in whom a SRE was observed (p = 0.005 and p = 0.001, respectively).

CONCLUSIONS

Changes in serum CTX levels seem to predict the potential for tumour control and the likelihood of developing an SRE in a sample of patients with solid tumours and bone metastases treated with ZA.

Osteonecrosis of the jaw and bisphosphonates in cancer: a narrative review

Bisphosphonate-associated osteonecrosis (BON) is a complication that almost exclusively affects the jaw bones. The clinical presentation of BON often mimics that of other conditions, such as routine dental disease, osteoradionecrosis or avascular necrosis; therefore, diagnosis can be difficult. As this complication has only been recognized within the past 10 years, management strategies for patients with BON are poorly defined. Physicians must choose between continuing the bisphosphonate therapy (to reduce the risk of skeletal complications in patients with metastatic bone disease or osteoporosis) and discontinuing the drug (to possibly improve the odds for tissue healing). A conservative or aggressive management strategy must be chosen with limited evidence that the outcome of either strategy will be successful. BON is most prevalent in patients with cancer using intravenous nitrogen-containing bisphosphonates. The pathobiology of this complication is not fully understood and the diagnosis relies on the clinical manifestations of the condition. Future research should focus on the pathobiological mechanisms involved in the development of BON, which could help explain why this complication affects only a small number of those who use bisphosphonates, and also suggest strategies for prevention and management.

Zoledronic acid delays disease progression of bone metastases from hepatocellular carcinoma

AIM

  We conducted a retrospective cohort study to investigate the efficacy of combination therapy with radiotherapy (RT) and zoledronic acid for bone metastases from hepatocellular carcinoma (HCC). Additionally, we investigated the efficacy of zoledronic acid for non-irradiated bone metastases.

METHODS

  This study consisted of 31 patients who had received RT for bone metastases. Twelve of these patients with 23 sites of bone metastases were also treated with zoledronic acid (Z group). In the Z group, 14 sites received RT and nine sites did not. Nineteen patients with 38 sites of bone metastases were not treated with zoledronic acid (non-Z group). In the non-Z group, 22 sites received RT and 16 did not. We compared survival, pain response, time to pain progression, radiographic response, time to radiographic progression, and safety between groups.

RESULTS

  While pain response rates were similar between the two groups, time to pain progression rates of irradiated and non-irradiated bone metastases was significantly lower in the Z (0% and 20% at 6 months, respectively) than in the non-Z group (34% and 66% at 6 months, respectively) (P = 0.045 and P = 0.005). Further, while radiographic response rates were similar between the two groups, time to radiographic progression rate of non-irradiated bone metastases was significantly lower in the Z (29% at 3 months) than in the non-Z group (91% at 3 months) (P = 0.009). No significant side-effects were documented.

CONCLUSION

  Zoledronic acid delayed the pain progression of both irradiated and non-irradiated bone metastases and the radiographic progression of non-irradiated bone metastases from HCC.

Microglia promote colonization of brain tissue by breast cancer cells in a Wnt-dependent way

Although there is increasing evidence that blood-derived macrophages support tumor progression, it is still unclear whether specialized resident macrophages, such as brain microglia, also play a prominent role in metastasis formation. Here, we show that microglia enhance invasion and colonization of brain tissue by breast cancer cells, serving both as active transporters and guiding rails. This is antagonized by inactivation of microglia as well as by the Wnt inhibitor Dickkopf-2. Proinvasive microglia demonstrate altered morphology, but neither upregulation of M2-like cytokines nor differential gene expression. Bacterial lipopolysacharide shifts tumor-educated microglia into a classical M1 phenotype, reduces their proinvasive function, and unmasks inflammatory and Wnt signaling as the most strongly regulated pathways. Histological findings in human brain metastases underline the significance of these results. In conclusion, microglia are critical for the successful colonization of the brain by epithelial cancer cells, suggesting inhibition of proinvasive microglia as a promising antimetastatic strategy.

Effects of high dose of zoledronic acid on superficial vascular network of membranous bone sites: an intravital study on rat calvarium

We evaluated the impact of high dose of zoledronic acid on the superficial vascular network parameters of a membranous bone site. During a 5-day follow-up, significant reduction of the vascular density is observed only in the treated group.

INTRODUCTION

The superficial vascularization is of great importance in membranous bone-healing process. A new rat calvarium intravital model was developed to study the short-term effect of a single high dose of zoledronic acid infusion on the superficial vascularization.

METHODS

Optical bone chambers were implanted in the bone tissue surface of Sprague-Dawley rats' calvarium. Nine rats were injected i.v. with 400 µg/kg of zoledronic acid (Z group), and nine rats were injected with vehicle (PSS group). A 5-day follow-up of the vascular network was made by the use of pictures analysis method.

RESULTS

The vascular density significantly decreases only in Z group but there was no significant difference between groups at individual time points. The total length of the vascular network decreases significantly in Z group only (p=0.003) with a significant higher decrease at D3 (p=0.04) and D5 (p=0.02) compared with control. The vascular density related to the smaller vessels (width, 5-10 µm) decreases significantly between T0 and D5 in Z group only (p=0.002).

CONCLUSIONS

With the help of an original intravital animal model a significant modifications on the total length of the vascular network and the vascular density of small vessels are highlighted on a membranous bone site.

Use of bisphosphonates and risk of postmenopausal breast cancer

PURPOSE

Bisphosphonates are commonly used for the treatment of osteoporosis and for prevention and treatment of skeletal lesions due to malignancy. However, the association between the use of bisphosphonates and the risk of developing breast cancer has not been reported.

PATIENTS AND METHODS

The Breast Cancer in Northern Israel Study is a population-based case-control study in northern Israel of patients with breast cancer and age-, clinic-, and ethnic-group matched controls. Use of bisphosphonates was assessed in 4,039 postmenopausal patients and controls, members of Clalit Health Services, using pharmacy records.

RESULTS

The use of bisphosphonates for longer than 1 year before diagnosis, but not for shorter than 1 year, was associated with a significantly reduced relative risk of breast cancer (odds ratio [OR], 0.61; 95% CI, 0.50 to 0.76). This association remained significant after adjustment for age, fruit, and vegetable consumption, sports activity, family history of breast cancer, ethnic group, body mass index, use of calcium supplements, hormone replacement therapy use, number of pregnancies, months of breast feeding, and age at first pregnancy (OR, 0.72; 95% CI, 0.57 to 0.90). Breast cancer risk did not change further if bisphosphonates were used for more years. Breast tumors identified in bisphosphonates users were more often estrogen receptor positive and less often poorly differentiated.

CONCLUSION

The use of bisphosphonates for longer than 1 year was associated with a 28% relative reduction in the risk of postmenopausal breast cancer. Tumors developing under bisphosphonates treatment tended to have a favorable prognostic factors profile.

Targeting mitochondria for cancer therapy

Mitochondria are the cells' powerhouse, but also their suicidal weapon store. Dozens of lethal signal transduction pathways converge on mitochondria to cause the permeabilization of the mitochondrial outer membrane, leading to the cytosolic release of pro-apoptotic proteins and to the impairment of the bioenergetic functions of mitochondria. The mitochondrial metabolism of cancer cells is deregulated owing to the use of glycolytic intermediates, which are normally destined for oxidative phosphorylation, in anabolic reactions. Activation of the cell death machinery in cancer cells by inhibiting tumour-specific alterations of the mitochondrial metabolism or by stimulating mitochondrial membrane permeabilization could therefore be promising therapeutic approaches.

Evaluation of liposomal clodronate for treatment of malignant histiocytosis in dogs

Malignant histiocytosis (MH) is an aggressive cancer derived from myeloid lineage cells in both dogs and humans. In dogs, the tumor is characterized by the rapid development of metastatic tumors in multiple sites, including especially the lungs and lymph nodes. Humans develop an analogous disease known as Langerhans cell histiocytosis, which primarily affects children and young adults. Because these tumors are often resistant to conventional chemotherapy, there is a need for newer therapeutic approaches. Systemic administration of liposomal clodronate (LC) has been shown to effectively deplete phagocytic cells (e.g., macrophages and dendritic cells) in mice. We investigated therefore whether LC could also be used to treat naturally occurring MH in dogs. First, the susceptibility of canine MH cells to LC-mediated killing was assessed in vitro. Then the clinical safety and effectiveness of LC as a treatment for MH was assessed in a pilot study in five pet dogs with spontaneous MH. We found that canine MH cells were very susceptible to LC-induced apoptotic cell death, whereas other tumor cell lines were resistant to killing by LC. Studies using labeled liposomes demonstrated that susceptibility to LC killing was directly related to the efficiency of liposome uptake. In pet dogs with spontaneous MH, we found that a short course of LC treatment elicited significant tumor regression in two of five treated animals. These findings suggest that liposomal delivery of clodronate and possibly other bisphosphonates may offer an effective new approach to treatment of histiocytic neoplasms in dogs and humans.

Skeletal morbidity in lung cancer patients with bone metastases: demonstrating the need for early diagnosis and treatment with bisphosphonates

BACKGROUND

The skeleton is one of the most frequent sites for metastases from non-small cell lung cancer (NSCLC), and skeletal-related events (SREs) can decrease quality of life (QOL). However, limited guidance exists regarding the diagnosis and treatment of bone metastases in patients with NSCLC.

METHODS

Data on the burden of skeletal morbidity and the diagnosis and treatment of bone metastases in patients with NSCLC were obtained from reviewing the published literature (PubMed) and presentations and abstracts from recent oncology congresses.

RESULTS

Bone metastases are common but underdiagnosed in patients with NSCLC. Most NSCLC patients with bone metastases develop > or =1 SRE during their lifetimes. As survival improves with new treatment modalities, the prevalence of SREs is likely to increase. Direct costs of SREs and their subsequent supportive care are approximately $28,000 per patient. Although bone metastases often are not diagnosed until after the onset of symptoms, early treatment can delay the onset of potentially debilitating SREs. In patients with NSCLC and other solid tumors (n=773), zoledronic acid (ZOL; 4 mg via 15-min infusion every 3 weeks) delayed the median time to first on-study SRE by >80 days compared with placebo (p=0.009). Moreover, ZOL significantly reduced the ongoing risk of SREs by 32% versus placebo (p=0.016).

CONCLUSIONS

Skeletal morbidity is an important concern in patients with NSCLC. The incidence of SREs is expected to increase as survival improves in this setting. Prevention of SREs with therapies such as ZOL may preserve patients' QOL and possibly reduce healthcare costs.

Bisphosphonates for osteoporosis treatment are associated with reduced breast cancer risk

BACKGROUND

Bisphosphanates are used primarily for the prevention and treatment of osteoporosis, and are also indicated for osseous complications of malignancy. In addition to their bone resorption properties, the most commonly used nitrogen-containing bisphosphonate compounds also inhibit protein prenylation, and thus may exert anti-tumour properties.

METHODS

To evaluate whether the use of these drugs may be associated with cancer, specifically breast cancer, we conducted a population-based case-control study in Wisconsin from 2003 to 2006. Participants included 2936 incident invasive breast cancer cases and 2975 population controls aged < 70 years. Bisphosphonate use and potential confounders were assessed by interview.

RESULTS

Using multivariable logistic regression, the odds ratio for breast cancer in current bisphosphonate users compared with non-users was 0.67 (95% confidence interval 0.51-0.89). Increasing duration of use was associated with a greater reduction in risk (P-trend=0.01). Risk reduction was observed in women who were not obese (P-interaction=0.005).

CONCLUSION

These results are suggestive of an additional benefit of the common use of bisphosphonates, in this instance, the reduction in breast cancer risk.

Lysosomal-mitochondrial axis in zoledronic acid-induced apoptosis in human follicular lymphoma cells

Bisphosphonates (BPs) are potent inhibitors of osteoclast function, widely used to treat excessive bone resorption associated with bone metastases, that also have anti-tumor activity. Zoledronic acid (ZOL) represents a potential chemotherapeutic agent for the treatment of cancer. ZOL is the most potent nitrogen-containing BPs, and it inhibits cell growth and induces apoptosis in a variety of cancer cells. Recently we demonstrated that accumulation of isopentenyl pyrophosphate and the consequent formation of a new type of ATP analog (ApppI) after mevalonate pathway inhibition by nitrogen-containing BPs strongly correlates with ZOL-induced cell death in cancer cells in vitro. In this study we show that ZOL-induced apoptosis in HF28RA human follicular lymphoma cells occurs exclusively via the mitochondrial pathway, involves lysosomes, and is dependent on mevalonate pathway inhibition. To define the exact signaling pathway connecting them, we used modified HF28RA cell lines overexpressing either BclXL or dominant-negative caspase-9. In both mutant cells, mitochondrial and lysosomal membrane permeabilization (MMP and LMP) were totally prevented, indicating signaling between lysosomes and mitochondria and, additionally, an amplification loop for MMP and/or LMP regulated by caspase-9 in association with farnesyl pyrophosphate synthetase inhibition. Additionally, the lysosomal pathway in ZOL-induced apoptosis plays an additional/amplification role of the intrinsic pathway independently of caspase-3 activation. Moreover, we show a potential regulation by Bcl-XL and caspase-9 on cell cycle regulators of S-phase. Our findings provide a molecular basis for new strategies concomitantly targeting cell death pathways from multiple sites.

Death receptor 5 agonist TRA8 in combination with the bisphosphonate zoledronic acid attenuated the growth of breast cancer metastasis

INTRODUCTION

Bone metastasis affects the majority of patients with advanced breast cancer and no adequate therapy exists. Bisphosphonates, like zoledronic acid, inhibit the osteolytic component of tumor growth in osseous tissues, but these drugs are not curative. The current study evaluated the combination of zoledronic acid with death receptor 5 agonists in an animal model of breast cancer bone metastasis.

MATERIALS AND METHODS

Female athymic nude mice (age 4-6 weeks, n=35) were inoculated with 200,000 luciferase-positive MDA- MB-435 cells by injection into the left ventricle. Animals were immediately imaged by bioluminescence technique and placed into one of the following therapy groups: Saline, hTRA8, hTRA8 + zoledronic acid, mTRA8, mTRA8 + zoledronic acid, or zoledronic acid monotherapy. DR5 agonists were given at 200 microg/dose and zoledronic acid 5 microg/dose, with mice treated biweekly for 4.5 weeks and imaged weekly.

RESULTS

Combination therapy containing either hTRA8 or mTRA8 with zoledronic acid significantly reduced the number of secondary lesions (7.67+2.2 and 7.5+1.7 lesions/mouse, respectively) compared to saline treated controls (12.1+/-1.56 lesions/mouse) as assessed by bioluminescence imaging (p<0.05). Additionally, monotherapy with hTRA8 resulted in a significant reduction in tumor number (8.3 +/- 2.9) compared to control animals. Total body tumor burden over time were significantly less in groups treated with hTRA8+zoledronic and mTRA8 + Zoledronic acid combination as compared with the saline control group. At day 33, both combination therapies and zoledronic acid monotherapy provided significant reduction in total tumor burden and tumor infiltration of hindlimbs by histomorphometry (p<0.05).

CONCLUSION

DR5 agonists in combination with bisphosphonates may be an acceptable combination therapy to reduce breast cancer growth in bone.

The level of ATP analog and isopentenyl pyrophosphate correlates with zoledronic acid-induced apoptosis in cancer cells in vitro

Bisphosphonates are potent inhibitors of osteoclast function widely used to treat excessive bone resorption associated, e.g., with bone metastases. They have also antitumor activity. However, it is unclear whether this reflects an indirect effect via inhibition of bone resorption or a direct antitumor effect. Nitrogen-containing bisphosphonates (N-BPs), including zoledronic acid (ZOL), act by inhibiting farnesyl pyrophosphate synthase (FPPS). The mevalonate pathway is blocked and the accumulation of isopentenyl pyrophosphate (IPP) consequently occurs. IPP is conjugated to AMP to form a novel ATP analog (ApppI). The present study was undertaken to clarify whether IPP and/or ApppI has a direct involvement in apoptosis caused by ZOL in different cancer cell lines. There are marked differences in ZOL-induced ApppI formation between different cancer cell lines. On this basis, we selected three cancer cell lines that differ significantly from each other in their ZOL-induced IPP and ApppI accumulation: human estrogen-dependent (MCF7) and estrogen-independent (MDA-MB 436) breast cancer cell lines and a human myeloma cell line (RPMI 8226). The amount of IPP/ApppI correlated with the capacity of cells to undergo apoptosis. Geranylgeraniol (GGOH), an intermediate of mevalonate metabolism, blocks both IPP and ApppI formation and to some degree ZOL-induced apoptosis in a cell line-dependent manner. In addition, lovastatin (LOV), an inhibitor of the enzyme HMGCoA reductase, completely blocks IPP/ApppI formation as determined by mass spectrometry analysis, but enhances apoptosis. In conclusion, the current data suggest that ZOL-induced IPP/ApppI formation can contribute to ZOL-induced apoptosis. This mechanism and the inhibition of protein prenylation, both outcomes of FPPS inhibition in mevalonate pathway, seem to act in concert in ZOL-induced apoptosis in cancer cells.

Frequency of zoledronic acid to prevent further bone loss in osteoporotic patients undergoing androgen deprivation therapy for prostate cancer

OBJECTIVE

To evaluate the efficacy of zoledronic acid (ZA) in osteoporotic patients with prostate cancer receiving either luteinizing hormone-releasing hormone agonists (LHRHA, which accelerate bone loss) or bicalutamide (which preserves bone mineral density, BMD) as androgen-deprivation therapy is the mainstay of treatment for advanced prostate cancer, and many patients are osteoporotic at presentation, with others becoming so on treatment.

PATIENTS AND METHODS

Fifty-eight osteoporotic men with non-metastatic prostate cancer were followed for 3 years. Patients were randomly assigned to receive either LHRHA (29) or bicalutamide (29). All received 4 mg ZA 3-monthly for 1 year. BMD was measured by dual energy X-ray absorptiometry at four times: 1 year before ZA; immediately before ZA; after five infusions; and 1 year afterwards. Bone turnover markers (BTMs) were measured at 3-monthly intervals on ZA and 1 year later. All patients had radiography of the thoracolumbar spine at baseline and after ZA.

RESULTS

Patients on LHRHA showed a 4.9% decrease in BMD before ZA, a 1.6% increase after ZA and a 3.0% decrease 1 year later, compared to 2.0% increase, 7.8% increase and 1.9% decrease, respectively, in those on bicalutamide. BTMs decreased significantly after ZA. Seven patients (12%) had vertebral fractures at baseline, with none deteriorating at 1 year; two (3.5%) developed mandibular osteonecrosis.

CONCLUSION

Before ZA, BMD decreased on LHRHA, but was maintained on bicalutamide. Treatment with 3-monthly ZA increased BMD and suppressed BTMs in osteoporotic patients both on LHRHA and bicalutamide, but to a greater extent in the latter. However, 1 year after the last infusion, BMD declined, suggesting that annual administration is inadequate in these patients. The optimum frequency might be related to BMD at time of bisphosphonate initiation.

[Antitumor activity of zoledronic acid]

Bisphosphonates are used for supportive treatment in bone metastases of malignant diseases. Advance in various therapeutic options, molecular targeted therapies of malignant diseases result in longer survival, and may bring a higher number of patients surviving until development of secondary lesions, e.g. bone metastases. This review summarizes the antitumor activity of the amino-bisphosphonate zoledronate, describing results of in vitro and animal model studies. Zoledronic acid treatment in patients with malignant solid tumors causing bone metastases prolongs their survival. According to the emerging, until now not too large amount of data, zoledronic acid may have a clinically significant and important direct antitumor activity which is resulted by many pathomechanical pathways summarized in this report. Randomized clinical trials are needed for evaluating real life antitumor activity of amino-bisphosphonates.

Identification of secondary targets of N-containing bisphosphonates in mammalian cells via parallel competition analysis of the barcoded yeast deletion collection

Growth competition assays using barcoded yeast deletion-mutants reveal the molecular targets of nitrogen containing bisphosphonates used for the treatment of bone cancers and osteoporosis.

Background

Nitrogen-containing bisphosphonates are the elected drugs for the treatment of diseases in which excessive bone resorption occurs, for example, osteoporosis and cancer-induced bone diseases. The only known target of nitrogen-containing bisphosphonates is farnesyl pyrophosphate synthase, which ensures prenylation of prosurvival proteins, such as Ras. However, it is likely that the action of nitrogen-containing bisphosphonates involves additional unknown mechanisms. To identify novel targets of nitrogen-containing bisphosphonates, we used a genome-wide high-throughput screening in which 5,936 Saccharomyces cerevisiae heterozygote barcoded mutants were grown competitively in the presence of sub-lethal doses of three nitrogen-containing bisphosphonates (risedronate, alendronate and ibandronate). Strains carrying deletions in genes encoding potential drug targets show a variation of the intensity of their corresponding barcodes on the hybridization array over the time.

Results

With this approach, we identified novel targets of nitrogen-containing bisphosphonates, such as tubulin cofactor B and ASK/DBF4 (Activator of S-phase kinase). The up-regulation of tubulin cofactor B may explain some previously unknown effects of nitrogen-containing bisphosphonates on microtubule dynamics and organization. As nitrogen-containing bisphosphonates induce extensive DNA damage, we also document the role of DBF4 as a key player in nitrogen-containing bisphosphonate-induced cytotoxicity, thus explaining the effects on the cell-cycle.

Conclusions

The dataset obtained from the yeast screen was validated in a mammalian system, allowing the discovery of new biological processes involved in the cellular response to nitrogen-containing bisphosphonates and opening up opportunities for development of new anticancer drugs.

The impact of zoledronic acid therapy in survival of lung cancer patients with bone metastasis

Bone metastases occur in 20-40% of patients with lung cancer. Recent studies demonstrate a direct antiproliferative effect of 3rd generation bisphosphonates (BPs) on lung tumors, which may influence the survival. Therefore, we examined the clinical impact of zoledronic acid (ZOL; Zometa), a 3rd generation BP, with a focus on the survival, time to progression and pain effect in lung cancer patients with bone metastases. Lung cancer patients (n = 144, Stage IV) with evidence of metastasis bone scan were included. Eighty-seven of 144 experienced bone pain and received ZOL, 4 mg i.v. every 21 days (Group A), whereas the other 57 patients received no ZOL (Group B). All patients were treated with a combination chemotherapy consisted of docetaxel 100 mg/m(2) and carboplatin AUC = 6. It was found that Group A had a statistically significant longer survival (p < 0.01) when compared to Group B. A statistically significant positive correlation was found between the number of cycles of therapy with ZOL and total patient survival (p < 0.01, Pearson correlation) and time to progression (p < 0.01). Pain effect of ZOL had no significant difference between the 2 groups of patients (p > 0.05). Urine N-telopeptide of type I collagen (NTx) levels decreased in patients with NTx < or = 29 nM BCE/mM creatinine at baseline after treatment with ZOL. The results of our study suggest that the addition of ZOL increases overall survival in lung cancer patients with bone metastases. The longer period of receiving ZOL, the better effect on survival and time to progression.

Chemokine CCL2/MCP-1 negatively regulates metastasis in a highly bone marrow-metastatic mouse breast cancer model

Bone is the most frequent site of breast cancer metastasis, and once such metastasis occurs, complete remission is extremely difficult to achieve. In an effort to define the mechanisms underlying metastatic spread of breast cancer to bone, we previously developed and characterized the highly bone metastatic 4T1E/M3 mouse breast cancer cells. We found that following injection into mice, 4T1E/M3 cells exhibited greater bone metastasis and greater in vitro anchorage-independent growth and cell migration than their parental cells (4T1E). We also found that expression of intracellular adhesion molecule-1 (ICAM-1) is crucially involved in these metastatic activities of 4T1E/M3 cells. In the present study, our analysis of gene and protein expression revealed that production of chemokine CCL2 (MCP-1) is dramatically reduced in 4T1E/M3 cells, and that restoration of CCL2 expression in 4T1E/M3 cells diminishes their metastasis to bone and lung. Overexpression of CCL2 in 4T1E/M3 cells significantly reduced not only in vitro anchorage-independent cell growth and cell migration, but also mRNA and cell surface expression of ICAM-1. Conversely, knocking down CCL2 in 4T1E parental cells augmented their metastatic spread to spine and lung. The expression of ICAM-1 was also upregulated in 4T1E-derived CCL2 knockdown cells. Taken together, these results suggest that CCL2 expression may negatively regulate breast cancer metastasis to bone marrow and lung in our model and that expression of ICAM-1 plays a crucial role in that process.

Efficient killing of human colon cancer stem cells by gammadelta T lymphocytes

Colon cancer comprises a small population of cancer stem cells (CSC) that is responsible for tumor maintenance and resistant to cancer therapies, possibly allowing for tumor recapitulation once treatment stops. We previously demonstrated that such chemoresistance is mediated by autocrine production of IL-4 through the up-regulation of antiapoptotic proteins. Several innate and adaptive immune effector cells allow for the recognition and destruction of cancer precursors before they constitute the tumor mass. However, cellular immune-based therapies have not been experimented yet in the population of CSCs. Here, we show that the bisphosphonate zoledronate sensitizes colon CSCs to Vgamma9Vdelta2 T cell cytotoxicity. Proliferation and production of cytokines (TNF-alpha and IFN-gamma) and cytotoxic and apoptotic molecules (TRAIL and granzymes) were also induced after exposure of Vgamma9Vdelta2 T cells to sensitized targets. Vgamma9Vdelta2 T cell cytotoxicity was mediated by the granule exocytosis pathway and was highly dependent on isoprenoid production by of tumor cells. Moreover, CSCs recognition and killing was mainly TCR mediated, whereas NKG2D played a role only when tumor targets expressed several NKG2D ligands. We conclude that intentional activation of Vgamma9Vdelta2 T cells by zoledronate may substantially increase antitumor activities and represent a novel strategy for colon cancer immunotherapy.

The bisphosphonate zoledronic acid decreases tumor growth in bone in mice with defective osteoclasts

Bisphosphonates (BPs), bone targeted drugs that disrupt osteoclast function, are routinely used to treat complications of bone metastasis. Studies in preclinical models of cancer have shown that BPs reduce skeletal tumor burden and increase survival. Similarly, we observed in the present study that administration of the Nitrogen-containing BP (N-BP), zoledronic acid (ZA) to osteolytic tumor-bearing Tax+ mice beginning at 6 months of age led to resolution of radiographic skeletal lesions. N-BPs inhibit farnesyl diphosphate (FPP) synthase, thereby inhibiting protein prenylation and causing cellular toxicity. We found that ZA decreased Tax+ tumor and B16 melanoma viability and caused the accumulation of unprenylated Rap1a proteins in vitro. However, it is presently unclear whether N-BPs exert anti-tumor effects in bone independent of inhibition of osteoclast (OC) function in vivo. Therefore, we evaluated the impact of treatment with ZA on B16 melanoma bone tumor burden in irradiated mice transplanted with splenic cells from src(-/-) mice, which have non-functioning OCs. OC-defective mice treated with ZA demonstrated a significant 88% decrease in tumor growth in bone compared to vehicle-treated OC-defective mice. These data support an osteoclast-independent role for N-BP therapy in bone metastasis.

Superparamagnetic nanovector with anti-cancer properties: gamma Fe2O3@Zoledronate

We elaborate a magnetic nanovector to vectorize Zoledronate, an anti-cancer interest molecule of the hydroxmethylenebisphosphonate's family. In fact, Zoledronate is a powerful adjuvant in the treatment of bone diseases such as osteoporosis and Paget's disease. But, recent studies have shown that in addition to anti-osteoclastic properties, it presents antitumour properties notably in the case of breast and prostate cancer. However, these properties cannot be exploited due to their very high affinity to divalent cations and their preferentially accumulation in bone. To overcome this problem, one strategy is the vectorization trough maghemite nanocrystal functionalization. The specific surface coating permits to consider gamma Fe(2)O(3)@Zoledronate as a drug delivery vehicle for therapeutic activity. The anchoring to the nanoparticle's surface allowed to increase their hydrophobicity and also to change the therapeutic target, increasing the Zoledronate intestinal absorption instead of their accumulation in bone. We show that Zoledronate link the nanoparticle surface through phosphonate groups. The biological in vitro tests performed on breast cancer cell line, MDA-MB 231, showed that gamma Fe(2)O(3)@Zoledronate have antiproliferative activity. In addition, the gamma Fe(2)O(3) core could be used as MRI contrast agent for a good therapeutic evaluation.

Bisphosphonates and osteonecrosis: potential treatment or serious complication?

They are commonly used to treat osteoporosis and other diseases that involve osteoclast-mediated bone resorption, including Paget's disease and multiple myeloma. Their use in treating osteonecrosis of the femoral head has been studied and theoretically holds promise. There are complications associated with these medications, however, including the development of osteonecrosis in the jaw.

An introduction to molecular targeted therapy of cancer

The rapidly advancing elucidation of molecular targets in human cancers during the last decade has provided an excellent basis for the development of novel therapeutics. A huge variety of potential target structures have been identified, many of which are already being exploited for therapeutic purposes. This review introduces the reader into the concept of molecular targeted therapies, and provides some prototypic examples.

New symmetrically esterified m-bromobenzyl non-aminobisphosphonates inhibited breast cancer growth and metastases

BACKGROUND

Although there was growing evidence in the potential use of Bisphosphonates (BPs) in cancer therapy, their strong osseous affinities that contrast their poor soft tissue uptake limited their use. Here, we developed a new strategy to overcome BPs hydrophilicity by masking the phosphonic acid through organic protecting groups and introducing hydrophobic functions in the side chain.

METHODOLOGY/PRINCIPAL FINDINGS

We synthesized non-nitrogen BPs (non N-BPs) containing bromobenzyl group (BP7033Br) in their side chain that were symmetrically esterified with hydrophobic 4-methoxphenyl (BP7033BrALK) and assessed their effects on breast cancer estrogen-responsive cells (T47D, MCF-7) as well as on non responsive ones (SKBR3, MDA-MB-231 and its highly metastatic derived D3H2LN subclone). BP7033Br ALK was more efficient in inhibiting tumor cell proliferation, migration and survival when compared to BP7033Br. Although both compounds inhibited tumor growth without side effects, only BP7033Br ALK abrogated tumor angiogenesis and D3H2LN cells-induced metastases formation.

CONCLUSION/SIGNIFICANCE

Taken together these data suggest the potential therapeutic use of this new class of esterified Bisphosphonates (BPs) in the treatment of tumor progression and metastasis without toxic adverse effects.

Zoledronic acid markedly improves bone mineral density for patients with monoclonal gammopathy of undetermined significance and bone loss

PURPOSE

Patients with monoclonal gammopathy of undetermined significance (MGUS) have increased rates of bone resorption, osteopenia, osteoporosis, and risk of fractures. This study was undertaken to determine the efficacy and safety of zoledronic acid for patients with MGUS and enhanced bone loss.

EXPERIMENTAL DESIGN

In this phase II open-label study, 54 patients with MGUS and osteopenia or osteoporosis were administered zoledronic acid 4 mg i.v. at 0, 6, and 12 months. The primary efficacy end point was bone mineral density, assessed using a dual-energy X-ray absorptiometry scan in the lumbar (L)-spine done at screening and at 13 months (1 month after the final zoledronic acid infusion).

RESULTS

At study end for all patients (N = 54), L-spine T-scores improved by a median of +0.27 (range, -0.38 to +3.91), corresponding to a median increase in bone mineral density of +15.0% (range, -18.0% to +1,140.0%; P < 0.0001). Hip T-scores improved by a median of +0.10 (range, -2.40 to +2.03), corresponding to a median increase of +6.0% (range, -350.0% to +165.0%). During the study, no new fractures, osteonecrosis of the jaw, or significant renal adverse events were reported.

CONCLUSIONS

Zoledronic acid administered i.v. at a dosage of 4 mg every 6 months for three doses total was well-tolerated and substantially improved bone mineral density for patients with MGUS and bone loss. Zoledronic acid may be effective for the prevention of new fractures in this high-risk population.

Design, synthesis, and biological evaluation of novel aminobisphosphonates possessing an in vivo antitumor activity through a gammadelta-T lymphocytes-mediated activation mechanism

A small series of aminobisphosphonates (N-BPs) structurally related to zoledronic acid was synthesized with the aim of improving activity toward activation of human gammadelta T cells and in turn their in vivo antitumor activity. The absence of the 1-OH moiety, together with the position and the different basicity of the nitrogen, appears crucial for antitumor activity. In comparison to zoledronic acid, compound 6a shows a greater ability to activate gammadelta T cells expression (100 times more) and a proapoptotic effect that is better than zoledronic acid. The potent activation of gammadelta T cells, in addition to evidence of the in vivo antitumor activity of 6a, suggests it may be a new potential drug candidate for cancer treatment.

Treatment of breast cancer with bone metastasis: bisphosphonate treatment - current and future

There are a variety of treatments for patients with bone metastases from breast cancer. These include bisphosphonates, antitumor endocrine and cytotoxic systemic therapies, radiotherapy to the metastatic site, radionucleotides, and conservative treatment (analgesics). The optimal combination treatment for bone metastases is not clear. Bisphosphonates are effective for reducing skeletal complications such as bone pain, pathological fracture, bone surgery, and hypercalcemia. Bisphosphonates are recommended as the gold standard therapy for breast cancer with bone metastases. Treatment guidelines tend to recommend starting a bisphosphonate at the time of diagnosis of bone metastases. Animal models have supported the prevention of bone metastasis by bisphosphonate therapy, but three major adjuvant clinical trials of the oral bisphosphonate clodronate have yielded conflicting results. However, our preliminary trial of an intravenous bisphosphonate, pamidronate, showed effective inhibition of bone metastases. The use of bisphosphonates, especially zoledronic acid, as adjuvant therapy is promising, but it is still investigational.

188Re-labelled gemcitabine/bisphosphonate (Gem/BP): a multi-functional, bone-specific agent as a potential treatment for bone metastases

PURPOSE

This study investigated the bone-binding affinity and biodistribution of a (188)Re-labelled gemcitabine/bisphosphonate (Gem/BP) conjugate, a multi-functional drug designed to deliver tumour-specific combined radiotherapy and chemotherapy to the bone using the high bone-binding affinity of the bisphosphonate group.

METHODS

The Gem/BP conjugate was labelled at high radiochemical purity with (188)Re. The bone-binding affinity of the (188)Re-Gem/BP was studied in vitro in purified hydroxyapatite emulsion and powdered bovine bone. In vivo biodistribution studies were carried out in normal BALB/c mice.

RESULTS

(188)Re-Gem/BP demonstrated strong and stable binding in both in vitro systems. In vivo (188)Re-Gem/BP showed bone uptake, rapid blood clearance and rapid elimination of unbound activity. The bone tissue demonstrated the highest concentration of bound radioactivity exempting the kidneys. Approximately 67% of retained whole-body activity was bound to the bone at 8 h after (188)Re-Gem/BP administration.

CONCLUSIONS

(188)Re-Gem/BP demonstrated high, selective and persistent bone binding and can be considered as a model compound for multi-functional bone-specific therapy for bone metastases.

Effect of zoledronic acid on serum angiogenic factors in patients with bone metastases

In this study we have investigated changes in circulating angiogenic factors after a single zoledronic acid intravenous infusion. Thirty consecutive patients who had histologically confirmed breast (n=20) and lung cancer (n=10) associated with confirmation of bone metastases were included in the study. Serum was also available from 10 healthy volunteers. Four mg of Zoledronic acid (Zometa, Novartis) was administered as a 15-min infusion in 100-ml normal saline on an outpatient basis. Venous blood for assessment of serum parameters was drawn just before the beginning of drug infusion and again at 7 and 28 days after the zoledronic acid infusion. Serum levels of VEGF and bFGF were assayed with ELISA kits. Serum VEGF and bFGF levels were not significantly different from healthy control groups (P>0.05). However, we found that serum VEGF levels in lung cancer patients were significantly higher than in patients with breast cancer and controls (P=0.009, and P=0.022, respectively). We found no significant correlation between serum VEGF and bFGF levels. No statistically significant changes were seen following infusion of zoledronic acid in patients with bone metastases for both serum VEGF and bFGF levels (P>0.05). Unlike previous studies, zoledronic acid did not appear to exert an angiogenic activity as there was no reduction of VEGF and bFGF circulating levels after zoledronic acid infusion.

Bisphosphonate-associated osteonecrosis can hide jaw metastases

BACKGROUND

Osteonecrosis of the jaw is a well known potential complication of bisphosphonate treatment but its pathogenesis is poorly understood. The current management of patients with bisphosphonate-associated osteonecrosis (BON) is based on "expert recommendations" and there is a recognized need of better evidence. We report two cases where BON hid jaw metastases and use them to discuss some limitations of the current recommendations.

PATIENTS

Two patients undergoing long-term I.V. amino-bisphosphonate treatment for metastatic cancer presented with areas of intraorally exposed jawbone. Bisphosphonate-associated osteonecrosis was diagnosed on the basis of medical history, clinical and radiological features. They underwent surgical resection of the affected jaw due to unrelenting pain and lack of response to conservative treatments.

RESULTS

Histological examination of the surgical specimen revealed cancer cells at the margins of the site of osteonecrosis. Our patients did not undergo bone biopsy according to current recommendations, due to lack of clinical and radiological signs suggestive of jaw metastases.

CONCLUSIONS

Our findings show that: i) patients with BON may also have jaw metastases; ii) there may not be clinical or imaging hints to this fact and; iii) that a biopsy based on careful selection of the site (with inclusion of necrotic margins) may be needed to reach the correct diagnosis. Further studies should be performed on this topic because of its very important prognostic implications.

Bisphosphonates: reducing the risk of skeletal complications from bone metastasis

Women with advanced breast cancer often develop bone metastases that are associated with skeletal-related events (SREs), which reduce quality of life and increase the risk of death. Because patients who experience one SRE are more likely to experience subsequent events, the goal of therapy is to preserve quality of life by delaying the onset of the first SRE and reducing the incidence of subsequent SREs. Bisphosphonates are used for clinical management of malignant bone disease, and data suggest that early treatment (e.g., before bone pain) may confer additional clinical benefit. Furthermore, data from subsets of zoledronic acid trials suggest that long-term bisphosphonate therapy may provide sustained clinical benefit throughout the disease course. Bisphosphonates are generally safe and well tolerated; adverse events are more often mild and transient. Zoledronic acid has proven efficacy for reducing risk of SREs, and ongoing studies are under way to evaluate customized treatment schedules.