Zoledronic acid reduces bone loss and tumor growth in an orthotopic xenograft model of osteolytic oral squamous cell carcinoma

Squamous cell carcinoma (SCC) is the most common form of oral cancer. Destruction and invasion of mandibular and maxillary bone frequently occurs and contributes to morbidity and mortality. We hypothesized that the bisphosphonate drug zoledronic acid (ZOL) would inhibit tumor-induced osteolysis and reduce tumor growth and invasion in a murine xenograft model of bone-invasive oral SCC (OSCC) derived from an osteolytic feline OSCC. Luciferase-expressing OSCC cells (SCCF2Luc) were injected into the perimaxillary subgingiva of nude mice, which were then treated with 100 μg/kg ZOL or vehicle. ZOL treatment reduced tumor growth and prevented loss of bone volume and surface area but had no effect on tumor invasion. Effects on bone were associated with reduced osteolysis and increased periosteal new bone formation. ZOL-mediated inhibition of tumor-induced osteolysis was characterized by reduced numbers of tartrate-resistant acid phosphatase-positive osteoclasts at the tumor-bone interface, where it was associated with osteoclast vacuolar degeneration. The ratio of eroded to total bone surface was not affected by treatment, arguing that ZOL-mediated inhibition of osteolysis was independent of effects on osteoclast activation or initiation of bone resorption. In summary, our results establish that ZOL can reduce OSCC-induced osteolysis and may be valuable as an adjuvant therapy in OSCC to preserve mandibular and maxillary bone volume and function.     

Zoledronic acid inhibits visceral metastases in the 4T1/luc mouse breast cancer model.

PURPOSE: It is established that bisphosphonates (BPs), specific inhibitors of osteoclasts, have beneficial effects on bone metastases of breast cancer. In addition, recent studies have reported that BPs have anticancer effects and suppress visceral metastases, too. However, the results of clinical studies are still conflicting. In the present study, we examined the effects of the BP zoledronic acid (ZOL), one of the most potent BPs currently available, on visceral metastases of breast cancer using an animal model in which mouse breast cancer cells 4T1/luc implanted at the orthotopic mammary fat pad spontaneously metastasize to multiple organs including bone, lung, and liver in female BALB/c mice. Experimental Design and RESULTS: The 4T1/luc-bearing mice received single or four i.v. injections of ZOL (0.5 or 5 microg/mouse) during the whole experimental period. Bone metastases were reduced by the ZOL treatment. More importantly, ZOL significantly suppressed lung and liver metastases. Furthermore, ZOL prolonged overall survival of the tumor-bearing mice. Of interest, apoptosis in 4T1/luc cells colonized in bone was increased by ZOL; however, those in lung were not changed. In vitro studies demonstrated that ZOL inhibited cell migration and invasion and promoted apoptosis of 4T1/luc cells. CONCLUSIONS: These results are consistent with the notion that ZOL affects breast cancer metastasis to visceral organs as well as bone. These effects of ZOL may be attributable to inhibition of migration and invasion of breast cancer cells. Clinical relevance of our experimental results needs to be determined in breast cancer patients with visceral metastases.     

Anti-tumor and anti-osteolysis effects of the metronomic use of zoledronic acid in primary and metastatic breast cancer mouse models

This study aims to determine the effect of metronomic (0.0125 mg/kg twice a week for 4 weeks) zoledronic acid (ZOL) on cancer propagation and osteolysis against both metastatic and primary breast cancer in mice model. From our results, metronomic ZOL resulted in a significant reduction of tumor burden and did not promote lung or liver metastasis. The metronomic ZOL appeared to be more effective than the conventional regimen (0.1 mg/kg once in 4 weeks) in reducing breast cancer tumor burden, and regulating its movement to lung and liver. This dosing schedule of ZOL showed great potential against metastatic breast cancer.     

Genetic manipulation of stromal cell-derived factor-1 attests the pivotal role of the autocrine SDF-1-CXCR4 pathway in the aggressiveness of breast cancer cells

Stromal cell-derived factor-1 (SDF-1), via its receptor CXCR4, has been implicated in metastasis of cancer, including breast cancer. Exogenous SDF-1 is known to regulate locomotion, chemotaxis and adhesion. The knowledge regarding the effect of autocrine SDF-1 on breast cancer cells is not available. The current study evaluated the effects of SDF-1 on the biological behaviour of breast cancer cells by genetically modifying the expression of SDF-1 in breast cancer cells. Two human breast cancer cell lines (MDA-MB-231 and MDA-MB-435s) and a human fetal lung fibroblast cell line (MRC5) were used. The expression of SDF-1 and the SDF-1 receptor, CXCR4 in the cell lines were studied. Expression cassettes of human SDF-1 and hammerhead ribozyme transgenes specifically targeting human SDF-1 were constructed and used to over-express SDF-1 or to knockout the expression of SDF-1 in cancer cells, respectively. Invasiveness, migration and growth of the genetically modified cells were assessed. SDF-1 was expressed in wild-type human breast cancer cell line MDA-MB-435s and fibroblast cell line MRC5, but not in MDA-MB-231 cell line. In contrast, CXCR4 expression was observed in all three cell lines tested. The ability of invasion and migration was significantly reduced in SDF-1 knockout MDA-MB-435s cells, compared with wild-type and vector control cells (p<0.01). On the other hand, SDF-1 transfected MDA-MB-231epsilonSDF1+/+ cells that stably expressed SDF-1 showed a different behaviour from MDA-MB-231SDF1+/- (plasmid control) and wild-type MDA-MB-231 cells, both being SDF-1 negative. MDA-MB-231epsilonSDF1+/+ cells displayed a higher degree of invasiveness and migration, compared with wild-type and MDA-MB-231SDF+/- cells (p<0.01). Furthermore, SDF1-knockout MDA-MB-435s cells showed a slower growth rate over a 7-day period compared with the respective control and wild-type MDA-MB-435s cells. In contrast, the growth of the SDF-1 transfected MDA-MB-231SDF1+/+ cells was markedly enhanced when compared with wild-type and vector control cells. Breast cancer cell lines, when equipped with the autocrine SDF-1-CXCR4 signal pathway, display aggressive behaviour, including an increase in invasiveness, migration together with faster growth. SDF-1, together with its receptor CXCR4 may provide important information for predicting the aggressive nature and constitute important therapeutic targets in human breast cancer.     

Breast cancer cells induce osteoclast formation by stimulating host IL-11 production and downregulating granulocyte/macrophage colony-stimulating factor

Breast cancer cells frequently metastasize to the skeleton, where they induce OCL formation and activity, resulting in extensive bone destruction. However, the mechanisms by which breast cancer cells mediate increased osteolysis remain unclear. To elucidate this point, we investigated how 3 human breast cancer cell lines, MDA-MB-231, MDA-MB-435 and MCF-7, induce OCL formation using a murine osteoblast-spleen cell coculture system and compared their effects with a human colorectal cancer cell line, HCT-15; a human lung cancer cell line, HT-1080; and a normal human breast cell line, HME. The breast cancer cell lines supported OCL formation only when osteoblasts were present in spleen cell cocultures, whilst the non-breast cancer cell lines and the normal breast cell line, HME, had no effect. Fractionation of BCCM by ultrafiltration established that osteoclastogenic activity was associated with factors having m.w. >3 kDa. Breast cancer cell lines produced primarily PTHrP, with lesser amounts of IL-6, IL-11 and TNF-alpha. The effect of BCCM on OCL formation in osteoblast-spleen cell cocultures was partially prevented by a neutralising antibody to human PTHrP and completely prevented by a neutralising antibody to either murine IL-11 or the murine IL-11 receptor; neutralising antibodies to human IL-6, IL-11 or TNF-alpha were without effect. BCCM or human PTHrP induced an increase in murine osteoblast IL-11 mRNA and protein production, effects that were prevented in the presence of a neutralising antibody to human PTHrP. The osteoclastogenic activity of IL-11 was mediated by enhancing osteoblast production of PGE(2) effects, which were abrogated by an inhibitor of cyclooxygenase. PGE(2) apparently enhanced OCL formation by downregulating GM-CSF production by spleen cells since recombinant murine GM-CSF inhibited OCL formation and a neutralising antibody to murine GM-CSF blocked these inhibitory effects. We conclude that breast cancer cells induce OCL formation by stimulating osteoblastic production of IL-11. The subsequent release of PGE(2) followed by inhibition of GM-CSF production by cells within the bone microenvironment plays an important part in mediating the effects of breast cancer cells on OCL formation and their resorptive activity.     

Tumor angiogenesis is associated with plasma levels of stromal-derived factor-1alpha in patients with multiple myeloma.

PURPOSE: Multiple myeloma is an incurable hematologic malignancy characterized by increased bone marrow angiogenesis and extensive lytic bone disease. We have previously shown that elevated levels of stromal-derived factor-1alpha (SDF-1alpha) in peripheral blood plasma are associated with osteolysis in multiple myeloma patients. We have now examined whether SDF-1alpha levels also correlate with angiogenesis. EXPERIMENTAL DESIGN: We examined the contribution of multiple myeloma plasma cell-derived SDF-1alpha in the stimulation of in vitro angiogenesis using a tube formation assay. We also collected trephine and peripheral blood plasma samples from patients with multiple myeloma to analyze microvessel density and SDF-1alpha levels, respectively. RESULTS: We show that multiple myeloma plasma cell line-derived conditioned medium containing SDF-1alpha stimulates in vitro angiogenesis. In addition, in a large cohort of patients with multiple myeloma and its precursor condition monoclonal gammopathy of undetermined significance, we confirm previous findings that plasma cell burden correlates with both angiogenesis and plasma levels of SDF-1alpha. We now extend these observations and show the novel finding that peripheral blood plasma levels of SDF-1alpha positively correlate with the degree of bone marrow angiogenesis in multiple myeloma and monoclonal gammopathy of undetermined significance patients. CONCLUSIONS: High levels of SDF-1alpha produced by multiple myeloma plasma cells promote osteolysis and bone marrow angiogenesis. Therefore, we propose that inhibition of SDF-1alpha may be an effective mechanism by which angiogenesis and osteolysis can be reduced in multiple myeloma patients.     

唑来膦酸在乳腺癌辅助治疗中的临床应用及机制探讨

第三代双膦酸盐类药物唑来膦酸是治疗乳腺癌骨转移公认的标准药物之一,但其在乳腺癌辅助治疗中的应用地位尚存在争议。目前临床研究结果表明,唑来膦酸辅助治疗不仅可以提高骨密度．而且可以降低乳腺癌的复发和转移。在低雌激素水平环境下,唑来膦酸可使早期乳腺癌患者得到生存获益．而且早期应用的益处优于延迟应用。唑来膦酸通过抑制肿瘤转移过程中的多条途径而发挥抗肿瘤作用。但唑来膦酸的最佳剂量、治疗周期及持续时间尚有待进一步的研究予以确认。     

TRAIL-R2 promotes skeletal metastasis in a breast cancer xenograft mouse model

Despite improvements in detection, surgical approaches and systemic therapies, breast cancer remains typically incurable once distant metastases occur. High expression of TRAIL-R2 was found to be associated with poor prognostic parameters in breast cancer patients, suggesting an oncogenic function of this receptor. In the present study, we aimed to determine the impact of TRAIL-R2 on breast cancer metastasis. Using an osteotropic variant of MDA-MB-231 breast cancer cells, we examine the effects of TRAIL-R2 knockdown in vitro and in vivo. Strikingly, in addition to the reduced levels of the proliferation-promoting factor HMGA2 and corresponding inhibition of cell proliferation, knockdown of TRAIL-R2 increased the levels of E-Cadherin and decreased migration. In vivo, these cells were strongly impaired in their ability to form bone metastases after intracardiac injection. Evaluating possible underlying mechanisms revealed a strong downregulation of CXCR4, the receptor for the chemokine SDF-1 important for homing of cancers cells to the bone. In accordance, cell migration towards SDF-1 was significantly impaired by TRAIL-R2 knockdown. Conversely, overexpression of TRAIL-R2 upregulated CXCR4 levels and enhanced SDF-1-directed migration. We therefore postulate that inhibition of TRAIL-R2 expression could represent a promising therapeutic strategy leading to an effective impairment of breast cancer cell capability to form skeletal metastases.     

Role of zoledronic acid in oncolytic virotherapy: Promotion of antitumor effect and prevention of bone destruction

Osteosarcoma is an aggressive malignant bone tumor that causes bone destruction. Although tumor‐specific replicating oncolytic adenovirus OBP‐301 induces an antitumor effect in an osteosarcoma tumor, it cannot prevent bone destruction. Zoledronic acid (ZOL) is a clinically available agent that inhibits bone destruction. In this study, we investigated the potential of combination therapy with OBP‐301 and ZOL against osteosarcomas with bone destruction. The antitumor activity of OBP‐301 and ZOL in monotherapy or combination therapy was assessed using three human osteosarcoma cell lines (143B, MNNG/HOS, SaOS‐2). The cytotoxic effect of OBP‐301 and/or ZOL was measured by assay of cell apoptosis. The effect of OBP‐301 and ZOL on osteoclast activation was investigated. The potential of combination therapy against tumor growth and bone destruction was analyzed using an orthotopic 143B osteosarcoma xenograft tumor model. OBP‐301 and ZOL decreased the viability of human osteosarcoma cells. Combination therapy with OBP‐301 and ZOL displayed a synergistic antitumor effect, in which OBP‐301 promoted apoptosis through suppression of anti‐apoptotic myeloid cell leukemia 1 (MCL1). Combination therapy significantly inhibited tumor‐mediated osteoclast activation, tumor growth and bone destruction compared to monotherapy. These results suggest that combination therapy of OBP‐301 and ZOL suppresses osteosarcoma progression via suppression of MCL1 and osteoclast activation.     

Efficacy of the third-generation bisphosphonate, zoledronic acid alone and combined with anti-cancer agents against small cell lung cancer cell lines

Small cell lung cancer (SCLC) is one of the most aggressive types of cancers because of its early development of regional and distant metastases. Novel and more effective therapeutic strategies for the treatment of this disease are necessary. Bisphosphonates (BP), originally developed to treat bone disease, have recently been identified as attractive cancer theraptic agents. In this study, we investigated the anti-proliferative effects of zoledronic acid (ZOL) as a single agent and in combination with other agents. ZOL inhibited both farnesylation and geranylgeranylation of RAS related proteins, induced apoptosis and inhibited the growth of eight out of twelve SCLC cell lines examined the in vitro. ZOL also significantly inhibited SCLC tumor growth and SBC-3 cells transplanted subcutaneously into nude mice. Its suppressive effect have not been completed, the addition effect of ZOL with other agents was examined. ZOL augmented the effects of paclitaxel, etoposide, cisplatinum and irinotecan synergistically, and imatinib mesylate additively. These findings indicate that ZOL and combined use of these agents may be promising therapeutic strategies for SCLC.     

Effects of oral UFT combined with or without zoledronic acid on bone metastasis in the 4T1/luc mouse breast cancer

Bone metastasis is one of the major causes of increased morbidity and eventual mortality in breast cancer patients. Therefore, intervention of bone metastases is one of the important targets in the management of breast cancer. In the present study, we examined the effects of the orally administrable chemotherapeutic agent UFT (a combination of tegafur and uracil at a molar ratio of 1:4) on bone metastases using an animal model of the 4T1/luc mouse breast cancer. The 4T1/luc cells developed spontaneous metastases to bone following orthotopic cell inoculation. Oral daily administration of UFT (20 mg/kg/day) significantly reduced the orthotopic tumor burden; however, the lower dose (15 mg/kg/day) did not. In contrast, histologic examination showed that both doses of UFT significantly suppressed bone metastases in a dose-dependent manner. Since clinical studies have demonstrated that bisphosphonates (BPs), specific inhibitors of osteoclastic bone resorption, are beneficial for breast cancer patients with bone metastases, we next examined the effects of UFT combined with the BP zoledronic acid (ZOL) on established bone metastases. The combination of UFT (20 mg/kg/day) with ZOL (250 microg/kg) caused an enhanced reduction of bone metastases compared with UFT alone. In vitro studies showed that 5-fluorouracil (5-FU), an active metabolite of UFT, and ZOL increased apoptosis in 4T1/luc cells and inhibited osteoclast-like cell formation in an additive fashion. Our results suggest that oral UFT is an effective chemotherapeutic agent for advanced breast cancer accompanying bone metastases and that the combination with BP increases its benefits for bone metastases.     

Zoledronic acid: multiplicity of use across the cancer continuum

Zoledronic acid (ZOL) has proven efficacy for reducing the risk of skeletal-related events in patients with bone metastases from a broad range of solid tumors and bone lesions from multiple myeloma. In a head-to-head trial in patients with breast cancer, ZOL demonstrated efficacy at least comparable with, and some benefits beyond those of, pamidronate. Several studies have also demonstrated additional benefits from ZOL, including preventing bone loss, and potential anticancer activity. Adding ZOL to anticancer therapy improved disease-free and overall survival in clinical trials in women receiving adjuvant endocrine therapy for breast cancer and in patients with newly diagnosed multiple myeloma. Thus, recent advances suggest that, in addition to its established role in reducing skeletal morbidity, ZOL might also help preserve bone health in patients with early stage breast cancer. The potential role of ZOL as an anticancer therapy in this setting is the focus of intense investigation and awaits insights from ongoing clinical trials.     

DHA is a more potent inhibitor of breast cancer metastasis to bone and related osteolysis than EPA

Breast cancer patients often develop bone metastasis evidenced by osteolytic lesions, leading to severe pain and bone fracture. Attenuation of breast cancer metastasis to bone and associated osteolysis by fish oil, rich in EPA and DHA, has been demonstrated previously. However, it was not known whether EPA and DHA differentially or similarly affect breast cancer bone metastasis and associated osteolysis. In vitro culture of parental and luciferase gene encoded MDA-MB-231 human breast cancer cell lines treated with EPA and DHA revealed that DHA inhibits proliferation and invasion of breast cancer cells more potently than EPA. Intra-cardiac injection of parental and luciferase gene encoded MDA-MB-231 cells to athymic NCr nu/nu mice demonstrated that DHA-treated mice had significantly less breast cancer cell burden in bone, and also significantly less osteolytic lesions than EPA-treated mice. In vivo cell migration assay as measured by luciferase intensity revealed that DHA attenuated cell migration specifically to the bone. Moreover, the DHA-treated group showed reduced levels of CD44 and TRAP positive area in bone compared to EPA-treated group. Breast cancer cell burden and osteolytic lesions were also examined in intra-tibially breast cancer cell injected mice and found less breast cancer cell growth and associated osteolysis in DHA-treated mice as compared to EPA-treated mice. Finally, doxorubicin-resistant MCF-7 (MCF-7dox) human breast cancer cell line was used to examine if DHA can improve sensitization of MCF-7dox cells to doxorubicin. DHA improved the inhibitory effect of doxorubicin on proliferation and invasion of MCF-7dox cells. Interestingly, drug resistance gene P-gp was also down-regulated in DHA plus doxorubicin-treated cells. In conclusion, DHA attenuates breast cancer bone metastasis and associated osteolysis more potently than EPA, possibly by inhibiting migration of breast cancer cell to the bone as well as by inhibiting osteoclastic bone resorption.     

Zoledronic acid: multiplicity of use across the cancer continuum

Zoledronic acid (ZOL) has proven efficacy for reducing the risk of skeletal-related events in patients with bone metastases from a broad range of solid tumors and bone lesions from multiple myeloma. In a head-to-head trial in patients with breast cancer, ZOL demonstrated efficacy at least comparable with, and some benefits beyond those of, pamidronate. Several studies have also demonstrated additional benefits from ZOL, including preventing bone loss, and potential anticancer activity. Adding ZOL to anticancer therapy improved disease-free and overall survival in clinical trials in women receiving adjuvant endocrine therapy for breast cancer and in patients with newly diagnosed multiple myeloma. Thus, recent advances suggest that, in addition to its established role in reducing skeletal morbidity, ZOL might also help preserve bone health in patients with early stage breast cancer. The potential role of ZOL as an anticancer therapy in this setting is the focus of intense investigation and awaits insights from ongoing clinical trials.     

TGF-beta promotion of Gli2-induced expression of parathyroid hormone-related protein, an important osteolytic factor in bone metastasis, is independent of canonical Hedgehog signaling

Breast cancer frequently metastasizes to bone, in which tumor cells receive signals from the bone marrow microenvironment. One relevant factor is TGF-β, which upregulates expression of the Hedgehog (Hh) signaling molecule, Gli2, which in turn increases secretion of important osteolytic factors such as parathyroid hormone-related protein (PTHrP). PTHrP inhibition can prevent tumor-induced bone destruction, whereas Gli2 overexpression in tumor cells can promote osteolysis. In this study, we tested the hypothesis that Hh inhibition in bone metastatic breast cancer would decrease PTHrP expression and therefore osteolytic bone destruction. However, when mice engrafted with human MDA-MB-231 breast cancer cells were treated with the Hh receptor antagonist cyclopamine, we observed no effect on tumor burden or bone destruction. In vitro analyses revealed that osteolytic tumor cells lack expression of the Hh receptor, Smoothened, suggesting an Hh-independent mechanism of Gli2 regulation. Blocking Gli signaling in metastatic breast cancer cells with a Gli2-repressor gene (Gli2-rep) reduced endogenous and TGF-β-stimulated PTHrP mRNA expression, but did not alter tumor cell proliferation. Furthermore, mice inoculated with Gli2-Rep-expressing cells exhibited a decrease in osteolysis, suggesting that Gli2 inhibition may block TGF-β propagation of a vicious osteolytic cycle in this MDA-MB-231 model of bone metastasis. Accordingly, in the absence of TGF-β signaling, Gli2 expression was downregulated in cells, whereas enforced overexpression of Gli2 restored PTHrP activity. Taken together, our findings suggest that Gli2 is required for TGF-β to stimulate PTHrP expression and that blocking Hh-independent Gli2 activity will inhibit tumor-induced bone destruction.     

唑来膦酸不同给药方式对骨癌痛大鼠镇痛作用的比较

目的:通过对鞘内注射和皮下注射两种给药方式的比较,探讨唑来膦酸对骨癌痛大鼠的镇痛效应及其可能机制.方法:将Walker 256乳腺癌细胞注入雌性SD大鼠胫骨以建立骨癌痛模型,单次或者持续给予唑来膦酸后,比较鞘内和皮下两种给药方式对大鼠痛行为学的影响.采用RT-PCR、Western blot和免疫荧光染色的实验方法观察...     

唑来膦酸在乳腺癌中抗肿瘤作用的研究进展

唑来膦酸(ZOL)是第三代双膦酸盐类药物的典型代表,在已上市的双膦酸盐类药物中应用最广泛、综合疗效最好,现已作为乳腺癌骨转移的常规治疗药物.多项临床前研究及临床研究已证实,唑来膦酸对肿瘤细胞有直接或间接的抑制作用,联合其他辅助治疗(化疗和内分泌治疗)可发挥协同作用,对改善乳腺癌患者术后生存、抑制复发及转移具有重要作用,本文就上述研究进展作一综述.     

Zoledronic acid, a third-generation bisphosphonate, inhibits cellular growth and induces apoptosis in oral carcinoma cell lines

Bisphosphonates (BPs) inhibit bone resorption by preventing osteoclast maturation and apoptosis induction. Recently, BPs have also been shown to have antitumor effects against various types of carcinomas in vitro and in vivo. In this study, we investigated the antitumor effect of zoledronic acid (ZOL), a third generation bisphosphonate, on proliferation, cell cycle and apoptosis of oral cancer cells. Direct antitumor effects of ZOL against four oral carcinoma cell lines (squamous cell carcinoma, HSC3, HSC4, SCCKN; salivary adenocarcinoma, HSY) were measured by WST assay. Apoptosis-related molecules were analyzed by Western blot analysis and cell cycle was analyzed by flow cytometry. ZOL had a dose-dependent antitumor effect in the four oral cancer cell lines. ZOL activated caspase-3, -8 and -9 and induced cellular apoptosis. Western blot analysis showed that ZOL increased cleaved anti-human poly(ADP-ribose) polymerase expression and decreased Bcl-2 and Bid expression. Treatment with ZOL increased the number of cells in apoptosis, sub G1 phase and S phase, and reduced the number of cells in the G0/G1 and G2/M phase in a concentration-dependent manner. ZOL inhibits cell proliferation and induces apoptosis of oral cancer cells in vitro. These findings suggest that ZOL might be beneficial in the treatment of oral carcinoma patients.     

Zoledronic acid protects against osteosarcoma‐induced bone destruction but lacks efficacy against pulmonary metastases in a syngeneic rat model

Osteosarcoma (OS) is the most common primary malignant tumor of bone in children and adolescents. In spite of successful control of the primary tumor, death from lung metastasis occurs in more than a third of patients. To investigate the efficacy of zoledronic acid (ZOL) on the development, progression and metastatic spread of OS, we used a rat model of OS, with features of the disease similar to human patients, including spontaneous metastasis to lungs. Rat OS cells were inoculated into the tibial marrow cavity of syngeneic rats. OS development was associated with osteolysis mixed with new bone formation, adjacent to the periosteum and extended into the surrounding soft tissue. Metastatic foci in the lungs formed 3–4 weeks postcancer cell transplantation. Treatment with a clinically relevant dose of ZOL was initiated 1 week after tumors were established and continued once weekly or as a single dose. ZOL preserved the integrity of both trabecular and cortical bone and reduced tumor‐induced bone formation. However, the overall tumor burden at the primary site was not reduced because of the persistent growth of cancer cells in the extramedullary space, which was not affected by ZOL treatment. ZOL treatment failed to prevent the metastatic spread of OS to the lungs. These findings suggest that ZOL as a single agent protects against OS‐induced bone destruction but lacks efficacy against pulmonary metastases in this rat model. ZOL may have potential value as an adjuvant therapy in patients with established OS.     

Skeletal-related Events and Clinical Outcomes in Patients with Bone Metastases and Normal Levels of Osteolysis: Exploratory Analyses

AimsHigh levels of bone resorption markers (e.g. N-telopeptide of type I collagen; NTX) have been correlated with increased risks of skeletal-related events and death in patients with bone metastases from solid tumours. However, the disease course has not been well characterised in patients with bone metastases but normal NTX levels. Therefore, the aim of this study was to evaluate the patterns of skeletal morbidity in patients with normal NTX levels.Materials and methodsExploratory analyses were carried out on patients with bone metastases from breast cancer, castration-resistant prostate cancer, non-small cell lung cancer or other solid tumours treated with zoledronic acid (ZOL) in phase III trials. The effects of covariates on the relative risk of death were estimated using the Cox proportional hazard model. The prognostic values of covariates were compared between patients with normal (<64 nmol/mmol creatinine) versus elevated (≥64 nmol/mmol creatinine) NTX levels.ResultsAmong patients with normal baseline NTX (n = 501), less than 10% developed elevated NTX levels before a skeletal-related event or death during ZOL treatment over 12 months. The prognostic factors identified in these analyses were mostly similar across NTX groups. However, some indicators of aggressive disease (e.g. visceral/cerebral metastases from breast cancer) were associated with poor clinical outcomes only in the normal NTX group.ConclusionsSkeletal-related events were generally not preceded or followed by transition to elevated NTX in patients treated with ZOL. Elevated baseline NTX and aggressive extraskeletal disease were independently associated with reduced survival.