Mechanisms of osteolytic bone destruction

Targeting nanoplatform synergistic glutathione depletion-enhanced chemodynamic, microwave dynamic, and selective-microwave thermal to treat lung cancer bone metastasis

Once bone metastasis occurs in lung cancer, the efficiency of treatment can be greatly reduced. Current mainstream treatments are focused on inhibiting cancer cell growth and preventing bone destruction. Microwave ablation (MWA) has been used to treat bone tumors. However, MWA may damage the surrounding normal tissues. Therefore, it could be beneficial to develop a nanocarrier combined with microwave to treat bone metastasis. Herein, a microwave-responsive nanoplatform (MgFe2O4@ZOL) was constructed. MgFe2O4@ZOL NPs release the cargos of Fe3+, Mg2+ and zoledronic acid (ZOL) in the acidic tumor microenvironment (TME). Fe3+ can deplete intracellular glutathione (GSH) and catalyze H2O2 to generate •OH, resulting in chemodynamic therapy (CDT). In addition, the microwave can significantly enhance the production of reactive oxygen species (ROS), thereby enabling the effective implementation of microwave dynamic therapy (MDT). Moreover, Mg2+ and ZOL promote osteoblast differentiation. In addition, MgFe2O4@ZOL NPs could target and selectively heat tumor tissue and enhance the effect of microwave thermal therapy (MTT). Both in vitro and in vivo experiments revealed that synergistic targeting, GSH depletion-enhanced CDT, MDT, and selective MTT exhibited significant antitumor efficacy and bone repair. This multimodal combination therapy provides a promising strategy for the treatment of bone metastasis in lung cancer patients.

Osteocytes: New Kids on the Block for Cancer in Bone Therapy

The tumor microenvironment plays a central role in the onset and progression of cancer in the bone. Cancer cells, either from tumors originating in the bone or from metastatic cancer cells from other body systems, are located in specialized niches where they interact with different cells of the bone marrow. These interactions transform the bone into an ideal niche for cancer cell migration, proliferation, and survival and cause an imbalance in bone homeostasis that severely affects the integrity of the skeleton. During the last decade, preclinical studies have identified new cellular mechanisms responsible for the dependency between cancer cells and bone cells. In this review, we focus on osteocytes, long-lived cells residing in the mineral matrix that have recently been identified as key players in the spread of cancer in bone. We highlight the most recent discoveries on how osteocytes support tumor growth and promote bone disease. Additionally, we discuss how the reciprocal crosstalk between osteocytes and cancer cells provides the opportunity to develop new therapeutic strategies to treat cancer in the bone.

Role of Osteocytes in Cancer Progression in the Bone and the Associated Skeletal Disease

PURPOSE OF REVIEW

The goal of this manuscript is to review the current knowledge on the role of osteocytes in cancer in the bone, discuss the potential of osteocytes as a therapeutic target, and propose future research needed to understand the crosstalk between cancer cells and osteocytes in the tumor niche.

RECENT FINDINGS

Numerous studies have established that cancer cells manipulate osteocytes to facilitate invasion and tumor progression in bone. Moreover, cancer cells dysregulate osteocyte function to disrupt physiological bone remodeling, leading to the development of bone disease. Targeting osteocytes and their derived factors has proven to effectively interfere with the progression of cancer in the bone and the associated bone disease. Osteocytes communicate with cancer cells and are also part of the vicious cycle of cancer in the bone. Additional studies investigating the role of osteocytes on metastases to the bone and the development of drug resistance are needed.

Predictive Periodontitis: The Most Promising Salivary Biomarkers for Early Diagnosis of Periodontitis

The primary cause of tooth loss in the industrialized world is periodontitis, a bacterial anaerobic infection whose pathogenesis is characterized by composite immune response. At present, the diagnose of periodontitis is made by a complete status check of the patient’s periodontal health; full-mouth plaque score, full-mouth bleeding score, probing depth, clinical attachment level, bleeding on probing, recessions, mobility, and migration are evaluated in order to provides a clear picture of the periodontal conditions of a single patient. Chair-side diagnostic tests based on whole saliva could be routinely used by periodontists for a very early diagnosis of periodontitis, monitoring, prognosis, and management of periodontal patients by biomarker detection, whose diagnostic validity is related to sensitivity and specificity. Recent paper reviews and meta-analyses have focused on five promising host derived biomarkers as candidate for early diagnosis of periodontitis: MMP-8 (Metalloproteinase-8), MIP-1α (Macrophage inflammatory protein-1 alpha), IL-1 β (Interleukin-1 beta), IL-6 (Interleukin-6), and HB (Hemoglobin), and their combinations. Chair-side Lab-on-a-chip (LOC) technology may soon become an important part of efforts to detect such biomarkers in saliva medium to improve worldwide periodontal health in developed nations as well as in underserved communities and poor countries. Their applications in preventive and predictive medicine is now fundamental, and is aimed at the early detection of risk factors or the presence or evolution of the disease, and in personalized medicine, which aims to identify tailor-made treatments for individual patients. The aim of the present paper is to be informative about host derived periodontal biomarkers and, in particular, we intend to report information about the most important immune response derived biomarkers and Hemoglobin as candidates to be routinely utilized in order to obtain a chair-side early diagnosis of periodontal disease.

Treatment of malignancy-associated hypercalcemia with cinacalcet: a paradigm shift

Palliation of symptoms related to malignancy-associated hypercalcemia (MAH) is essential and clinically meaningful for patients, given the continued poor prognosis, with high morbidity and mortality associated with this disease process. Historically, agents have been temporizing, having no impact on patient morbidity nor survival. We suggest that cinacalcet can be an efficacious agent to be taken orally, reducing patients' time in the hospital/clinic settings. It is well-tolerated and maintains serum calcium levels in the normal range, while targeted cancer treatments can be employed. This has a direct, major impact on morbidity. Maintaining eucalcemia can increase quality of life, while allowing targeted therapies time to improve survival. Given that our case (and others) showed calcium reduction in MAH, there is promising evidence that cinacalcet can be more widely employed in this setting. Future consideration should be given to studies addressing the efficacy of cinacalcet in calcium normalization, improvement of quality of life, and impact on survival in patients with MAH. Though the exact mechanism of action for cinacalcet's reduction in calcium in this setting is not currently known, we can still afford patients the possible benefit from it.

The Emerging Role of Osteocytes in Cancer in Bone

Advances in the last decade have established the osteocyte, the most abundant cell in bone, as a dynamic and multifunctional cell capable of controlling bone homeostasis by regulating the function of both osteoblasts and osteoclasts. In addition, accumulating evidence demonstrates that osteocyte function is altered in several skeletal disorders, and targeting osteocytes and their derived factors improves skeletal health. Despite the remarkable progress in our understanding of osteocyte biology, there has been a paucity of information regarding the role of osteocytes in the progression of cancer in bone. Exciting, recent discoveries suggest that tumor cells communicate with osteocytes to generate a microenvironment that supports the growth and survival of cancer cells and stimulates bone destruction. This review features these novel findings and discussions regarding the impact of chemotherapy on osteocyte function and the potential of targeting osteocytes for the treatment of cancer in bone. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Serum Levels of Carboxyterminal Propeptide of Type I Procollagen in Cancer Patients with Osteoblastic and Osteolytic Bone Metastases

Serial monitoring of serum and urinary markers of bone regeneration may provide an indirect assessment of the activity of bone metastases. We measured serum levels of carboxyterminal propeptide of type I procollagen (PICP), a new marker of bone formation, in 236 control subjects, stratified according to age and sex, and in 122 cancer patients: 80 with breast cancer (BC) (42 with osteolytic bone metastases) and 42 with prostate cancer (PC) (31 with osteoblastic bone metastases). An inverse correlation between age and serum PICP levels was found in healthy men (r = -0.30), but not in women. PICP levels were significantly higher in patients with osteoblastic metastases compared to age-matched control subjects and patients with advanced disease not involving the skeleton. The sensitivity of PICP was 64% for detecting osteoblastic metastases, and 12% for detecting osteolytic metastases. Serum PICP determination may have a diagnostic role for osteoblastic activity.

Bisphosphonates and other bone agents for breast cancer

BACKGROUND

Bone is the most common site of metastatic disease associated with breast cancer (BC). Bisphosphonates inhibit osteoclast-mediated bone resorption, and novel targeted therapies such as denosumab inhibit other key bone metabolism pathways. We have studied these agents in both early breast cancer and advanced breast cancer settings. This is an update of the review originally published in 2002 and subsequently updated in 2005 and 2012.

OBJECTIVES

To assess the effects of bisphosphonates and other bone agents in addition to anti-cancer treatment: (i) in women with early breast cancer (EBC); (ii) in women with advanced breast cancer without bone metastases (ABC); and (iii) in women with metastatic breast cancer and bone metastases (BCBM).

SEARCH METHODS

In this review update, we searched Cochrane Breast Cancer's Specialised Register, CENTRAL, MEDLINE, Embase, the World Health Organization's International Clinical Trials Registry Platform (WHO ICTRP) and ClinicalTrials.gov on 19 September 2016.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing: (a) one treatment with a bisphosphonate/bone-acting agent with the same treatment without a bisphosphonate/bone-acting agent; (b) treatment with one bisphosphonate versus treatment with a different bisphosphonate; (c) treatment with a bisphosphonate versus another bone-acting agent of a different mechanism of action (e.g. denosumab); and (d) immediate treatment with a bisphosphonate/bone-acting agent versus delayed treatment of the same bisphosphonate/bone-acting agent.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data, and assessed risk of bias and quality of the evidence. The primary outcome measure was bone metastases for EBC and ABC, and a skeletal-related event (SRE) for BCBM. We derived risk ratios (RRs) for dichotomous outcomes and the meta-analyses used random-effects models. Secondary outcomes included overall survival and disease-free survival for EBC; we derived hazard ratios (HRs) for these time-to-event outcomes where possible. We collected toxicity and quality-of-life information. GRADE was used to assess the quality of evidence for the most important outcomes in each treatment setting.

MAIN RESULTS

We included 44 RCTs involving 37,302 women.In women with EBC, bisphosphonates were associated with a reduced risk of bone metastases compared to placebo/no bisphosphonate (RR 0.86, 95% confidence interval (CI) 0.75 to 0.99; P = 0.03, 11 studies; 15,005 women; moderate-quality evidence with no significant heterogeneity). Bisphosphonates provided an overall survival benefit with time-to-event data (HR 0.91, 95% CI 0.83 to 0.99; P = 0.04; 9 studies; 13,949 women; high-quality evidence with evidence of heterogeneity). Subgroup analysis by menopausal status showed a survival benefit from bisphosphonates in postmenopausal women (HR 0.77, 95% CI 0.66 to 0.90; P = 0.001; 4 studies; 6048 women; high-quality evidence with no evidence of heterogeneity) but no survival benefit for premenopausal women (HR 1.03, 95% CI 0.86 to 1.22; P = 0.78; 2 studies; 3501 women; high-quality evidence with no heterogeneity). There was evidence of no effect of bisphosphonates on disease-free survival (HR 0.94, 95% 0.87 to 1.02; P = 0.13; 7 studies; 12,578 women; high-quality evidence with significant heterogeneity present) however subgroup analyses showed a disease-free survival benefit from bisphosphonates in postmenopausal women only (HR 0.82, 95% CI 0.74 to 0.91; P < 0.001; 7 studies; 8314 women; high-quality evidence with no heterogeneity). Bisphosphonates did not significantly reduce the incidence of fractures when compared to placebo/no bisphosphonates (RR 0.77, 95% CI 0.54 to 1.08, P = 0.13, 6 studies, 7602 women; moderate-quality evidence due to wide confidence intervals). We await mature overall survival and disease-free survival results for denosumab trials.In women with ABC without clinically evident bone metastases, there was no evidence of an effect of bisphosphonates on bone metastases (RR 0.96, 95% CI 0.65 to 1.43; P = 0.86; 3 studies; 330 women; moderate-quality evidence with no heterogeneity) or overall survival (RR 0.89, 95% CI 0.73 to 1.09; P = 0.28; 3 studies; 330 women; high-quality evidence with no heterogeneity) compared to placebo/no bisphosphonates however the confidence intervals were wide. One study reported a trend towards an extended period of time without a SRE with bisphosphonate compared to placebo (low-quality evidence). One study reported quality of life and there was no apparent difference in scores between bisphosphonate and placebo (moderate-quality evidence).In women with BCBM, bisphosphonates reduced the SRE risk by 14% (RR 0.86, 95% CI 0.78 to 0.95; P = 0.003; 9 studies; 2810 women; high-quality evidence with evidence of heterogeneity) compared with placebo/no bisphosphonates. This benefit persisted when administering either intravenous or oral bisphosphonates versus placebo. Bisphosphonates delayed the median time to a SRE with a median ratio of 1.43 (95% CI 1.29 to 1.58; P < 0.00001; 9 studies; 2891 women; high-quality evidence with no heterogeneity) and reduced bone pain (in 6 out of 11 studies; moderate-quality evidence) compared to placebo/no bisphosphonate. Treatment with bisphosphonates did not appear to affect overall survival (RR 1.01, 95% CI 0.91 to 1.11; P = 0.85; 7 studies; 1935 women; moderate-quality evidence with significant heterogeneity). Quality-of-life scores were slightly better with bisphosphonates than placebo at comparable time points (in three out of five studies; moderate-quality evidence) however scores decreased during the course of the studies. Denosumab reduced the risk of developing a SRE compared with bisphosphonates by 22% (RR 0.78, 0.72 to 0.85; P < 0.001; 3 studies, 2345 women). One study reported data on overall survival and observed no difference in survival between denosumab and bisphosphonate.Reported toxicities across all settings were generally mild. Osteonecrosis of the jaw was rare, occurring less than 0.5% in the adjuvant setting (high-quality evidence).

AUTHORS' CONCLUSIONS

For women with EBC, bisphosphonates reduce the risk of bone metastases and provide an overall survival benefit compared to placebo or no bisphosphonates. There is preliminary evidence suggestive that bisphosphonates provide an overall survival and disease-free survival benefit in postmenopausal women only when compared to placebo or no bisphosphonate. This was not a planned subgroup for these early trials, and we await the completion of new large clinical trials assessing benefit for postmenopausal women. For women with BCBM, bisphosphonates reduce the risk of developing SREs, delay the median time to an SRE, and appear to reduce bone pain compared to placebo or no bisphosphonate.

Emerging therapeutic targets in cancer induced bone disease: A focus on the peripheral type 2 cannabinoid receptor

Skeletal complications are a common cause of morbidity in patients with primary bone cancer and bone metastases. The type 2 cannabinoid (Cnr2) receptor is implicated in cancer, bone metabolism and pain perception. Emerging data have uncovered the role of Cnr2 in the regulation of tumour-bone cell interactions and suggest that agents that target Cnr2 in the skeleton have potential efficacy in the reduction of skeletal complications associated with cancer. This review aims to provide an overview of findings relating to the role of Cnr2 receptor in the regulation of skeletal tumour growth, osteolysis and bone pain, and highlights the many unanswered questions and unmet needs. This review argues that development and testing of peripherally-acting, tumour-, Cnr2-selective ligands in preclinical models of metastatic cancer will pave the way for future research that will advance our knowledge about the basic mechanism(s) by which the endocannabinoid system regulate cancer metastasis, stimulate the development of a safer cannabis-based therapy for the treatment of cancer and provide policy makers with powerful tools to assess the science and therapeutic potential of cannabinoid-based therapy. Thus, offering the prospect of identifying selective Cnr2 ligands, as novel, alternative to cannabis herbal extracts for the treatment of advanced cancer patients.

Navigating the bone marrow niche: translational insights and cancer-driven dysfunction

The bone marrow niche consists of stem and progenitor cells destined to become mature cells such as haematopoietic elements, osteoblasts or adipocytes. Marrow cells, influenced by endocrine, paracrine and autocrine factors, ultimately function as a unit to regulate bone remodelling and haematopoiesis. Current evidence highlights that the bone marrow niche is not merely an anatomic compartment; rather, it integrates the physiology of two distinct organ systems, the skeleton and the marrow. The niche has a hypoxic microenvironment that maintains quiescent haematopoietic stem cells (HSCs) and supports glycolytic metabolism. In response to biochemical cues and under the influence of neural, hormonal, and biochemical factors, marrow stromal elements, such as mesenchymal stromal cells (MSCs), differentiate into mature, functioning cells. However, disruption of the niche can affect cellular differentiation, resulting in disorders ranging from osteoporosis to malignancy. In this Review, we propose that the niche reflects the vitality of two tissues - bone and blood - by providing a unique environment for stem and stromal cells to flourish while simultaneously preventing disproportionate proliferation, malignant transformation or loss of the multipotent progenitors required for healing, functional immunity and growth throughout an organism's lifetime. Through a fuller understanding of the complexity of the niche in physiologic and pathologic states, the successful development of more-effective therapeutic approaches to target the niche and its cellular components for the treatment of rheumatic, endocrine, neoplastic and metabolic diseases becomes achievable.

11C-choline PET/CT identifies osteoblastic and osteolytic lesions in patients with metastatic prostate cancer

AIM

The aim of this study was to compare C-choline PET/CT, prostate-specific antigen (PSA), PSA kinetics, and C-choline uptake in recurrent metastatic prostate cancer patients with osteoblastic and osteolytic bone metastases.

PATIENTS AND METHODS

We retrospectively analyzed 140 patients with the following criteria: (a) positive bone lesions identified with C-choline PET/CT and validated as true positive by histology (14.2%), correlative imaging (33.4%), or clinical follow-up (52.4%); (b) after radical prostatectomy (67.9%) or primary radiotherapy (22.1%); (c) proven biochemical relapse with rising PSA levels; (d) no chemotherapy, zoledronic acid, or palliative bone external beam radiation therapy previously administrated during biochemical relapse; and (f) asymptomatic for bone pain. Lesions were categorized as osteoblastic, osteolytic, or bone marrow lesions. Patients were divided into osteoblastic and osteolytic patient groups.

RESULTS

C-Choline PET/CT detected oligometastatic bone disease (1-3 lesions) in 98 (70%) of the 140 patients and multiple bone lesions in 42 (30%) of the 140 patients. By per-lesion analysis of 304 lesions, there were 184 osteoblastic, 99 osteolytic, and 21 bone marrow lesions.By per-patient analysis, 97 (69.3%) of the 140 patients were in the osteoblastic group, whereas 43 (30.7%) of the 140 patients were in the osteolytic group. Statistically significant differences in SUVmax (P < 0.001), fast PSA doubling time (P = 0.01), and PSA velocity (P = 0.01) were observed between osteoblastic (lower values) and osteolytic (higher values) groups. By multivariate analysis, fast PSA doubling time was a significant predictor for osteolytic lesions.

CONCLUSIONS

We demonstrated differences in PSA kinetics and SUVmax between osteolytic and osteoblastic lesions. C-Choline PET/CT may identify patients that could benefit from early targeted therapies, depending on the type of bone lesions expressed.

New concepts of breast cell communication to bone

Lactation is the most extreme case of normal physiological bone loss during a lifetime, and breast cancers have a strong tendency to metastasize to bone. In both the physiological and pathological circumstances, parathyroid hormone-related peptide (PTHrP) plays a central role. Until recently there were no regulatory mechanisms to explain the induction of endocrine PTHrP secretion from breast cells during lactation. The mammary epithelium possesses a local serotonin signaling system which drives PTHrP expression during lactation and in breast cancer cells. The mammary gland serotonin system is highly induced in response to alveolar dilation due to milk secretion. Discovery of serotonergic control of PTHrP suggests that it may be possible to manipulate the breast-to-bone axis by targeting serotonin signaling.

Molecular signaling pathways mediating osteoclastogenesis induced by prostate cancer cells

Background

Advanced prostate cancer commonly metastasizes to bone leading to osteoblastic and osteolytic lesions. Although an osteolytic component governed by activation of bone resorbing osteoclasts is prominent in prostate cancer metastasis, the molecular mechanisms of prostate cancer-induced osteoclastogenesis are not well-understood.

Methods

We studied the effect of soluble mediators released from human prostate carcinoma cells on osteoclast formation from mouse bone marrow and RAW 264.7 monocytes.

Results

Soluble factors released from human prostate carcinoma cells significantly increased viability of naïve bone marrow monocytes, as well as osteoclastogenesis from precursors primed with receptor activator of nuclear factor κ-B ligand (RANKL). The prostate cancer-induced osteoclastogenesis was not mediated by RANKL as it was not inhibited by osteoprotegerin (OPG). However inhibition of TGFβ receptor I (TβRI), or macrophage-colony stimulating factor (MCSF) resulted in attenuation of prostate cancer-induced osteoclastogenesis. We characterized the signaling pathways induced in osteoclast precursors by soluble mediators released from human prostate carcinoma cells. Prostate cancer factors increased basal calcium levels and calcium fluctuations, induced nuclear localization of nuclear factor of activated t-cells (NFAT)c1, and activated prolonged phosphorylation of ERK1/2 in RANKL-primed osteoclast precursors. Inhibition of calcium signaling, NFATc1 activation, and ERK1/2 phosphorylation significantly reduced the ability of prostate cancer mediators to stimulate osteoclastogenesis.

Conclusions

This study reveals the molecular mechanisms underlying the direct osteoclastogenic effect of prostate cancer derived factors, which may be beneficial in developing novel osteoclast-targeting therapeutic approaches.

Induction of retinol-binding protein 4 and placenta-specific 8 expression in human prostate cancer cells remaining in bone following osteolytic tumor growth inhibition by osteoprotegerin

New drugs that inhibit the osteoprotegerin (OPG)/receptor activator of NF-κB ligand (RANKL)/RANK pathway have demonstrated efficacy for the treatment of bone metastasis. Toxicities induced by these drugs, however, including osteonecrosis of the jaw and hypocalcemia, may adversely affect therapy. The aim of this study was to identify additional therapeutic targets that can be combined with OPG/RANKL/RANK pathway inhibition in the treatment of prostate cancer bone metastasis. We established a stable transfectant that produces high levels of OPG mRNA and protein from PC-3 human prostate cancer cells (PC3-OPG). The culture medium of PC3-OPG cells significantly inhibited the differentiation of mouse monocytes into mature osteoclasts. Furthermore, when PC3-OPG cells were injected into the bones of nude mice, bone destruction and tumor-induced osteoclast formation were reduced. Injection into bone of the mixtures containing equal amounts of green fluorescent protein (GFP)-expressing PC-3 cells (PC3-GFP) and PC3-OPG cells also reduced bone destruction, compared to the control mixture. PC3-GFP cells were subsequently isolated from bone tumors and used for microarray analysis to assess changes in gene expression following osteolytic tumor growth inhibition by OPG. We selected the top 10 upregulated genes based on results from microarrays and confirmed mRNA expression of each gene by RT-PCR. The expression patterns of retinol-binding protein 4 (RBP4) and placenta-specific 8 (PLAC8) were consistent with microarray results. Expression of these genes was also increased in the bone tumors of PC3-GFP/PC3-OPG-injected mice. Knockdown of both RBP4 and PLAC8 by siRNA inhibited the growth of PC-3 cells in vitro. Thus, RBP4 and PLAC8 may become new therapeutic targets for prostate cancer bone metastasis, in combination with OPG/RANKL/RANK pathway inhibition.

MRMT-1 rat breast carcinoma cells and models of bone metastases: improvement of an in vitro system to mimic the in vivo condition

Breast cancer frequently metastasizes to the skeleton thus interrupting the normal bone remodeling process and causing bone degradation. Having suitable in vitro and in vivo models is important for understanding the pathogenesis and developing treatment strategies for bone metastasis in humans. In order to improve and characterize an in vitro model of bone metastasis from breast cancer an MRMT-1 rat breast carcinoma cell line or their conditioned medium were directly co-cultured with rat monocytes. To confirm the in vitro results, an in vivo model, in which MRMT-1 cells were inoculated into the proximal surface of the tibia, was also adopted. Osteoclast viability, activity and differentiation showed a significant increase (p<0.05, p<0.0005, p<0.0005, respectively) between co-culture with MRMT-1 cells and the other culture conditions. Moreover, scanning electron microscopy analysis, phalloidin staining and 4'-6-diamidino-2-phenylindole (DAPI) nuclear acid staining confirmed that co-culture with MRMT-1 cells also induced a greater differentiation in osteoclast structure and morphology. Finally, the in vivo outcome at 3 weeks showed the presence of a severe osteolytic lesion, thus confirming the effectiveness of the present in vitro results. These results demonstrated an improvement of an in vitro model of bone metastases from breast cancer in which co-culture with MRMT-1 cells was shown to be a dynamic system that closely mimics the in vivo situation. The present study may help improve our understanding of the complex "vicious cycle" between osteoblasts, osteoclasts and tumor cells.

Bisphosphonates and other bone agents for breast cancer

BACKGROUND

Bone is the most common site of metastatic disease associated with breast cancer (BC). Bisphosphonates inhibit osteoclast-mediated bone resorption, and novel targeted therapies such as denosumab, inhibit key pathways in the vicious cycle of bone metastases.

OBJECTIVES

To assess the effect of bisphosphonates on skeletal-related events (SREs), bone pain, quality of life (QoL), recurrence and survival in women with breast cancer with bone metastases (BCBM), advanced breast cancer (ABC) without clinical evidence of bone metastases and early breast cancer (EBC).To assess the effect of denosumab on SREs, bone pain and (QoL) in women with (BCBM).

SEARCH METHODS

We searched the Specialised Register maintained by the Cochrane Breast Cancer Group (CBCGSR), MEDLINE, EMBASE and the WHO International Cancer Trials Registry Platform (WHO ICTRP) on 30 April 2011. We conducted additional handsearching of journals and proceedings of key meetings.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing: (a) bisphosphonates and control, or different bisphosphonates in women with BCBM; (b) denosumab and bisphosphonates in women with BCBM; (c) bisphosphonates and control in women with ABC; (d) bisphosphonates and control in women with EBC; and (e) early versus delayed bisphosphonate treatment in women with EBC.

DATA COLLECTION AND ANALYSIS

Two review authors (MW and NP) independently assessed the trials and extracted the data. We collected toxicity information from the trials.

MAIN RESULTS

We included thirty-four RCTs. In nine studies (2806 patients with BCBM), comparing bisphosphonates with placebo or no bisphosphonates, bisphosphonates reduced the SRE risk by 15% (risk ratio (RR) 0.85; 95% confidence interval (CI) 0.77 to 0.94; P = 0.001). This benefit was most certain with intravenous (i.v.) zoledronic acid (4 mg) (RR 0.59; 95% CI 0.42 to 0.82); i.v. pamidronate (90 mg) (RR 0.77; 95% CI 0.69 to 0.87); and i.v. ibandronate (RR 0.80; 95% CI 0.67 to 0.96). A direct comparison of i.v. zoledronic acid and i.v. pamidronate confirmed at least equivalent efficacy in a single large study. In three studies (3405 patients with BCBM), compared with bisphosphonates, subcutaneous (s.c.) denosumab was more effective in reducing the risk of SREs (RR 0.78; 95% CI 0.72 to 0.85; P < 0.00001).Bisphosphonates reduced the SRE rate in 12 studies (median reduction 28%, range 14% to 48%), with statistically significant reductions reported in 10 studies. Women with BCBM treated with bisphosphonates showed significant delays in the median time to SREs. Compared with placebo or no bisphosphonates, treatment with bisphosphonates significantly improved bone pain in six out of eleven studies. Improvements in global QoL with bisphosphonates compared to placebo were reported in two out of five studies (both ibandronate studies). Treatment with bisphosphonates did not appear to affect survival in women with BCBM. Compared to i.v. zoledronic acid, denosumab also significantly reduced the SRE rate, delayed the time to SREs and prolonged the time in developing pain for patients with no or mild pain at baseline; but there was no difference in survival between patients treated with denosumab and zoledronic acid.Bisphosphonates in women with ABC without clinically evident bone metastases did not reduce the incidence of bone metastases, or improve survival in three studies (320 patients).In seven studies (7847 patients with EBC), currently there is no evidence supporting bisphosphonates in reducing the incidence of bone metastases compared to no bisphosphonates (RR 0.94; 95% CI 0.82 to 1.07; P = 0.36). In three studies (2190 patients with EBC), early bisphosphonate treatment also did not significantly reduce the incidence of bone metastases compared to delayed bisphosphonate treatment (RR 0.73; 95% CI 0.40 to 1.33; P = 0.31). Currently, there is insufficient evidence to make a conclusion about the role of adjuvant bisphosphonates in reducing visceral metastases, locoregional recurrence and total recurrence, or improving survival. There was strong heterogeneity in EBC studies examining the outcomes of total recurrence and survival.Reported toxicity was generally mild. Renal toxicity and osteonecrosis of the jaw (ONJ) have been identified as potential problems with bisphosphonate use. ONJ was reported at similar rates for patients on denosumab compared to zoledronic acid. This highlighted a need for maintaining good oral care, prior to and during treatment, for patients who received long-term bone agents.

AUTHORS' CONCLUSIONS

In women with clinically evident BCBM, bisphosphonates (oral and i.v.) and denosumab (s.c.) reduced the risk of developing SREs, as well as delaying the time to SREs. Some bisphosphonates may also reduce bone pain and may improve QoL. The optimal timing and duration of treatment for patients with BCBM remains uncertain. There is currently insufficient evidence to support the routine use of bisphosphonates as adjuvant treatment for patients with EBC. However, a number of large clinical trials investigating bisphosphonates in EBC have completed accrual and are awaiting results.

Breast adenocarcinoma MCF-7 cell line induces spontaneous osteoclastogenesis via a RANK-ligand-dependent pathway

The metastasis of breast cancer to the skeleton is a serious clinical problem resulting in hypercalcemia, bone fragility and insurmountable pain. The invasion of bony tissue by neoplastic cells usually very rapidly affects the balance between bone apposition and bone resorption. In order to elucidate a mechanism for cancer-induced osteoclastogenesis, cells from a human breast cancer line, MCF-7, were directly co-cultured with murine monocytes RAW 264.7 type CRL 2278. Compared with controls, co-culture of MCF-7 induced differentiation of multinucleated cells by membrane-bound and soluble receptor activator of NF-kB ligand (RANKL) as quantified by ELISA, Western blot analysis, transmission electron microscopy (TEM), and immunocytochemistry. The aim of this study was to determine an in vitro model system of MCF-7 human breast cancer cells grown together with monocytes to show that expression of RANKL promotes osteoclastogenesis, which may indicate a mechanism for the development of osteolytic lesions in breast cancer bone metastasis.

Bone-derived SDF-1 stimulates IL-6 release via CXCR4, ERK and NF-kappaB pathways and promotes osteoclastogenesis in human oral cancer cells

Oral squamous cell carcinoma (SCC) has a striking tendency to invade to bone. The chemokine stromal cell-derived factor-1 (SDF-1) is constitutively secreted by osteoblasts and plays a key role in homing of hematopoietic cells to the bone marrow. Interleukin (IL)-6 plays an important role in osteoclastogenesis. Herein, we found that SDF-1α increased the secretion of IL-6 in cultured human SCC cells, as shown by reverse transcriptase–polymerase chain reaction and enzyme-linked immunosorbent assay. SDF-1α also increased the surface expression of chemokine receptor 4 (CXCR4) in SCC cells. CXCR4-neutralizing antibody, CXCR4-specific inhibitor (AMD3100) or small interfering RNA against CXCR4 inhibited SDF-1α-induced increase IL-6 production. The transcriptional regulation of IL-6 by SDF-1α was mediated by phosphorylation of extracellular signal-regulated kinases (ERKs) and activation of the nuclear factor-kappa B (NF-κB) components p65 and p50. The binding of p65 and p50 to the NF-κB element on the IL-6 promoter was enhanced by SDF-1α. In addition, IL-6 antibody antagonized the SCC-conditioned medium-increased osteoclastogenesis. These results suggested that SDF-1α from osteoblasts could induce release of IL-6 in human SCC cells via activation of CXCR4, ERK and NF-κB pathway and thereby promote osteoclastogenesis.

Aseptic loosening of total joint replacements: mechanisms underlying osteolysis and potential therapies

Total joint replacement, although considered an excellent surgical procedure, can be complicated by osteolysis induced by implant particles and subsequent aseptic loosening of the implant. The pathogenesis of implant-associated osteolysis includes inflammatory and osteolytic processes. The sustained chronic inflammatory response initiated by particulate debris at the implant-bone interface is manifested by recruitment of a wide array of cell types. These cells include macrophages, fibroblasts, giant cells, neutrophils, lymphocytes, and--most importantly--osteoclasts, which are the principal bone resorbing cells. The 'cellular response' entails secretion of osteoclastogenic and inflammatory cytokines that favor exacerbated osteoclast activity and enhanced osteolysis. An appreciation of the complex network that leads to these cellular and inflammatory responses will form a foundation on which to develop therapeutic interventions to combat inflammatory periprosthetic bone loss.

RANKL-dependent and RANKL-independent mechanisms of macrophage-osteoclast differentiation in breast cancer

The cellular and humoral mechanisms accounting for tumour osteolysis in metastatic breast cancer are uncertain. Osteoclasts, the specialised multinucleated cells responsible for tumour osteolysis, are derived from monocyte/macrophage precursors. Breast cancer-derived tumour-associated macrophages (TAMs) are capable of osteoclast differentiation but the cellular and humoral mechanisms controlling this activity are uncertain. In this study, TAMs were isolated from primary breast cancers and cultured in the presence and absence of cytokines/growth factors influencing osteoclastogenesis. Extensive TAM-osteoclast differentiation occurred only in the presence of RANKL and M-CSF; this process was inhibited by OPG and RANK:Fc, decoy receptors for RANKL. Breast cancer-derived fibroblasts and human bone stromal cells expressed mRNA for RANKL, OPG and TRAIL, and co-culture of these fibroblasts with human monocytes stimulated osteoclast formation by a RANKL-dependent mechanism. Osteoclast formation and lacunar resorption also occurred by a RANKL-independent mechanism when the conditioned medium from breast cancer cells, MDA-MB-231 and MCF-7, was added (with M-CSF) to monocyte cultures. Our findings indicate that TAMs in breast cancer are capable of osteoclast differentiation and that breast cancer-derived fibroblasts and breast cancer cells contribute to this process by producing soluble factors that influence osteoclast formation by RANKL-dependent and RANKL-independent mechanisms respectively.

Treatment for Myeloma Bone Disease: Table 1

Multiple myeloma (MM) is a B cell malignancy characterized by enhanced bone loss commonly associated with diffuse osteopenia, focal lytic lesions, pathologic fractures, hypercalcemia, and bony pain. Bone destruction in MM results from asynchronous bone turnover wherein increased osteoclastic bone resorption is not accompanied by a comparable increase in bone formation. Consequently, patients with MM frequently require radiation therapy, surgery, and analgesic medications. The recent development of minimally invasive surgical procedures such as kyphoplasty allows patients with myeloma with vertebral compression fractures to have immediate improvement in their quality of life with shorter hospital stays. Bisphosphonates are specific inhibitors of osteoclastic activity, and these agents have been evaluated in patients with MM with bone disease during the past 15 years. Monthly i.v. infusions of either pamidronate or zoledronic acid have reduced the skeletal complications among patients with MM and are now a mainstay of myeloma therapy. Orally administered bisphosphonates, in contrast, have shown little ability to slow the development of skeletal complications in these patients. Although preclinical studies suggest that nitrogen-containing bisphosphonates have potent antitumor effects, clinical trials will be necessary, probably at higher doses given more slowly, to establish their possible antitumor effects clinically. Moreover, recent advances in the use of bone-seeking radiopharmaceuticals make these attractive therapeutic candidates to combine with bisphosphonates or radiosensitizing drugs (e.g., bortezomib) to achieve a synergistic effect. As our understanding of the pathophysiology of myeloma bone disease continues to grow, new target therapies will continue to emerge, offering new and more advanced options for the management of myeloma bone disease.

Oral Bisphosphonates as Adjuvant Therapy for Operable Breast Cancer

Bone is the most common site of metastatic spread from primary operable breast cancer, causing pain, fractures, and hypercalcemia. This spread depends on the release of osteolytic substances by the cancer cells, which activate osteoclasts to cause bone resorption. The osteoclasts also release growth factors that can act back on the cancer cells to activate growth. This vicious circle thereby facilitates the growth of metastases in bone, thus making this a preferential site for relapse. Agents, such as the bisphosphonates, which block osteoclast function, have been shown to reduce the progression of established bone metastases. The oral bisphosphonate clodronate (1,600 mg/d) is effective for treatment of patients with bone metastases. When used as adjuvant therapy, given to patients with operable breast cancer for 2 years, clodronate has been reported to significantly reduce the risk of bone metastases during the 2-year study period [19 clodronate patients versus 35 placebo patients; hazard ratio (HR), 0.546; P=0.03] and 5-year study period (51 clodronate patients versus 73 placebo patients; HR, 0.692; P=0.04) with a significant reduction in mortality (HR, 0.768; P=0.048). This benefit, together with the low toxicity and safety of clodronate, supports its use as additional adjuvant therapy for patients with primary breast cancer. Further, similarly designed trials are under way to establish the optimal duration of therapy, the efficacy in stage I disease, and the relative potential of other bisphosphonates, particularly the more powerful aminobisphosphonates, such as ibandronate and zoledronate.

Myeloma bone disease and treatment options

Multiple myeloma (MM) is a B-cell malignancy characterized by enhanced bone loss commonly associated with a diffuse osteopenia, focal lytic lesions, pathologic fractures, hypercalcemia, and bony pain. Bone destruction in MM results from asynchronous bone turnover wherein increased osteoclastic bone resorption is not accompanied by a comparable increase in bone formation. Recent characterization of osteoclast-activating factors (OAFs), receptor activator of nuclear factor-kappaB (RANK) ligand (RANKL)-osteoprotegerin-RANK system, and inhibitors of Wnt signaling have provided a better understanding of myeloma bone disease in molecular level. The development of minimally invasive surgical procedures such as kyphoplasty and vertebroplasty allows myeloma patients with vertebral compression fractures to have immediate improvement in quality of life and shorter hospital stays. Monthly intravenous infusion of either pamidronate or zoledronic acid have reduced the skeletal complications among MM patients and are now a mainstay of myeloma therapy. Orally administered bisphosphonates, in contrast, have shown little ability to slow the development of skeletal complications in these patients. Although pre-clinical studies suggest nitrogen-containing bisphosphonates have potent anti-tumor effects, clinical trials will be necessary, probably at higher doses given more slowly, to establish their possible anti-tumor effects clinically. As our understanding of the pathophysiology of myeloma bone disease continues to increase, new target therapies will continue to emerge offering new and more advanced options for the management of myeloma bone disease.

Map kinase c-JUN N-terminal kinase mediates PMMA induction of osteoclasts

Erosive osteolysis induced by implant-derived wear debris is mediated by recruitment and activation of osteoclasts in a pro-inflammatory microenvironment that is enriched with osteoclastogenic and pro-inflammatory cytokines such as RANKL and tumor necrosis factor alpha (TNF-alpha). These cytokines activate the transcription factor NF-kappaB and MAP kinases, including c-Jun, Erks, and p38, all known to be essential for the development of osteoclasts. We have recently documented that TNF and RANKL play a pivotal role in the development of inflammatory osteolysis. We have also found that polymethyl methacrylate (PMMA) particles stimulate osteoclastogenesis, at least in part, by induction of RANKL, TNF, and by activation of NF-kappaB and MAP kinases. More importantly, our data indicate that inhibitors of NF-kappaB and the MAP kinases p38 and ERK abrogate particle-induced osteoclastogenesis. In the current study, we investigated if inhibition of c-Jun N-Terminal kinase (JNK) pathway alters PMMA-induced osteoclastogenesis. Our findings point out that PMMA particles activate the JNK pathway in wild-type and TLR4-null (endotoxin-resistant) osteoclast precursors. This activation was selectively blocked in a dose-dependent fashion by the JNK inhibitor SP600125. Most importantly, we provide evidence that SP600125 inhibits osteoclast formation in a reversible manner. Collectively, our findings demonstrate that activation of the JNK pathway is essential for basal and PMMA-stimulated osteoclastogenesis, and buttress the potential significance of targeting the JNK pathway to inhibit osteolysis.

Malignant melanoma and bone resorption

The cellular and humoral mechanisms accounting for osteolysis in skeletal metastases of malignant melanoma are uncertain. Osteoclasts, the specialised multinucleated cells that carry out bone resorption, are derived from monocyte/macrophage precursors. We isolated tumour-associated macrophages (TAMs) from metastatic (lymph node/skin) melanomas and cultured them in the presence and absence of osteoclastogenic cytokines and growth factors. The effect of tumour-derived fibroblasts and melanoma cells on osteoclast formation and resorption was also analysed. Melanoma TAMs (CD14+/CD51-) differentiated into osteoclasts (CD14-/CD51+) in the presence of receptor activator for nuclear factor kappaB ligand (RANKL) and macrophage-colony stimulating factor. Tumour-associated macrophage-osteoclast differentiation also occurred via a RANKL-independent pathway when TAMs were cultured with tumour necrosis factor-alpha and interleukin (IL)-1alpha. RT-PCR showed that fibroblasts isolated from metastatic melanomas expressed RANKL messenger RNA and the conditioned medium of cultured melanoma fibroblasts was found to be capable of inducing osteoclast formation in the absence of RANKL; this effect was inhibited by the addition of osteoprotegerin (OPG). We also found that cultured human SK-Mel-29 melanoma cells produce a soluble factor that induces osteoclast differentiation; this effect was not inhibited by OPG. Our findings indicate that TAMs in metastatic melanomas can differentiate into osteoclasts and that melanoma fibroblasts and melanoma tumour cells can induce osteoclast formation by RANKL-dependent and RANKL-independent mechanisms, respectively.

Additive growth inhibitory effects of ibandronate and antiestrogens in estrogen receptor-positive breast cancer cell lines

INTRODUCTION

Bisphosphonates are inhibitors of osteoclast-mediated tumor-stimulated osteolysis, and they have become standard therapy for the management of bone metastases from breast cancer. These drugs can also directly induce growth inhibition and apoptosis of osteotropic cancer cells, including estrogen receptor-positive (ER+) breast cancer cells.

METHODS

We examined the anti-proliferative properties of ibandronate on two ER+ breast cancer cell lines (MCF-7 and IBEP-2), and on one ER negative (ER-) cell line (MDA-MB-231). Experiments were performed in steroid-free medium to assess ER regulation and the effect of ibandronate in combination with estrogen or antiestrogens.

RESULTS

Ibandronate inhibited cancer cell growth in a dose- and time-dependent manner (approximate IC50: 10(-4) M for MCF-7 and IBEP-2 cells; 3 x 10(-4) M for MDA-MB-231 cells), partly through apoptosis induction. It completely abolished the mitogenic effect induced by 17beta-estradiol in ER+ breast cancer cells, but affected neither ER regulation nor estrogen-induced progesterone receptor expression, as documented in MCF-7 cells. Moreover, ibandronate enhanced the growth inhibitory action of partial (4-hydroxytamoxifen) and pure (ICI 182,780, now called fluvestrant or Faslodex) antiestrogens in estrogen-sensitive breast cancer cells. Combination analysis identified additive interactions between ibandronate and ER antagonists.

CONCLUSION

These data constitute the first in vitro evidence for additive effects between ibandronate and antiestrogens, supporting their combined use for the treatment of bone metastases from breast cancer.

Myeloma bone disease

The major clinical manifestation of multiple myeloma is related to the osteolytic bone destruction. The bone disease can lead to pathologic fractures, spinal cord compression, hypercalcemia, and pain. It is also a major cause of morbidity and mortality in these patients. These patients frequently require radiation therapy, surgery and analgesic medications. Bisphosphonates are specific inhibitors of osteoclastic activity, and these agents have been evaluated in myeloma patients with bone disease during the past 15 years. Several large randomized trials have been conducted in myeloma patients also receiving chemotherapy. Orally administered bisphosphonates have shown little ability to slow the development of skeletal complications in these patients. In contrast, more potent intravenous monthly infusions of either pamidronate or zoledronic acid have reduced the skeletal complications among these patients and are now a mainstay of myeloma therapy. A number of other types of new anti-bone-resorptive agents are also in early clinical development.

Bisphosphonates for breast cancer

BACKGROUND

Bone is the most common site of metastatic disease associated with breast cancer affecting more than half of women during the course of their disease. Bone metastases are a significant cause of morbidity due to pain, pathological fractures, hypercalcaemia and spinal cord compression, and contribute to mortality. Bisphosphonates, which inhibit osteoclast-mediated bone resorption, are standard care for tumour-associated hypercalcaemia, and have been shown to reduce bone pain, improve quality of life, and to delay skeletal events and reduce their number in patients with multiple myeloma. Several randomized controlled trials have evaluated the role of bisphosphonates in breast cancer.

OBJECTIVES

To assess the effect of bisphosphonates on skeletal events, bone pain, quality of life and survival in women with early and advanced breast cancer.

SEARCH STRATEGY

Randomized controlled trials were identified using the specialized register maintained by the Cochrane Breast Cancer Group (the search was applied to the databases Medline, Central/CCTR, Embase, CancerLit, and included handsearches from a number of other relevant sources). See: Cochrane Collaboration Collaborative Review Group in Breast Cancer search strategy.

SELECTION CRITERIA

Randomized controlled trials evaluating skeletal events in women with metastatic breast cancer and early breast cancer comparing: 1. treatment with a bisphosphonate with the same treatment without a bisphosphonate 2. treatment with one bisphosphonate with treatment with a different bisphosphonate.

DATA COLLECTION AND ANALYSIS

Studies were selected by two independent reviewers. Studies fulfilling the eligibility criteria were evaluated for quality, particularly concealment of allocation to randomized groups. Data were extracted from the published papers or abstracts independently by the two primary reviewers for each of the specified endpoints (skeletal events, bone pain, quality of life and survival). Data on skeletal events and survival were presented as numbers of events, risk ratios and ratios of event rates. Meta-analyses were based on the fixed-effects model (Mantel-Haenszel). Subjective qualitative ratings were used to summarize the quality of life and pain data.

MAIN RESULTS

Twenty one randomized studies were included. All studies in advanced breast cancer included women with clinically evident bone metastases (osteolytic and/or mixed osteolytic/osteoblastic) by plain xray and/or radionucleotide bone scans. In nine studies that included 2189 women with advanced breast cancer and existing bone metastases, bisphosphonates reduced the risk of developing a skeletal event by 17% (RR 0.83; 95% confidence interval (CI) 0.78-0.89; P < 0.00001). This effect was more modest, but still highly significant if episodes of hypercalcaemia were excluded (10 studies, 2656 women, RR 0.85; 95% CI 0.79-0.91 P = 0.0001). Overall, intravenous bisphosphonates reduce the risk of developing a skeletal event by 17 % (95% CI 0.78-0.89) compared with oral bisphosphonates, which reduce the risk of developing a skeletal event by 16 % (95% CI 0.76-0.93). Of the currently available bisphosphonates, 4 mg IV zolendronate reduces the risk of developing a skeletal event by 41% (RR 0.59, 95% CI 0.42-0.82), compared with 33 % by 90 mg IV pamdronate (RR 0.77, 95% CI 0.69-0.87), 18 % by 6 mg IV ibandronate (RR 0.82, 95% CI 0.67-1.00), 14 % by 50mg oral ibandronate (RR 0.86, 95% CI 0.73-1.02) and 16 % by 1600 mg oral clodronate (RR 0.84, 95% CI 0.72-0.98). Compared with placebo or no bisphosphonate, with bisphosphonates the skeletal event rate was lower in all of 12 studies in women with clinically evident bone metastases (median reduction of 29%, range 14-48%); statistically significant reductions were reported in 10 trials (four intravenous pamidronate, two oral clodronate, one intravenous ibandronate and two oral ibandronate, a single intravenous zolendronate study). Studies of intravenous zolendronate, pamidronate and oral clodronate in women with advanced breast cancer and clinically evident bone metastases showed significant delays in the median time to a skeletal event. Event-free survival was also reported to be longer in women receiving 6 mg of ibandronate compared with controls. Compared with placebo or no bisphosphonate, with bisphosphonates significant improvements in bone pain were reported in seven studies (90 mg iv pamidronate, 4 mg iv zolendronate, 6 mg iv ibandronate, 1600 mg oral clodronate and 50 mg oral ibandronate). Eight studies tested the effect of bisphosphonates compared with placebo on patient-rated quality of life using a referenced scale. Improvements in global quality of life were reported in only the three studies of iv and oral ibandronate. Treatment with bisphosphonates does not appear to affect survival in women with advanced breast cancer. Intravenous zolendronate (4 mg) appeared to be as effective as pamidronate (90mg) when directly compared in a single randomized double-blind study, based on the risk of developing a skeletal related event, the median time to first skeletal event and skeletal morbidity rate (events per year). Updated re-evaluation of the primary data in the overall population, by multiple event analysis using the method of Anderson-Gill, showed a reduction in the risk of developing any skeletal complication (including hypercalcamia) of 20 % (zolendronate 4 mg compared with pamidronate 90 mg, RR = 0.80, 95% CI 0.66 - 0.97, p = 0.025), suggesting a possible advantage of zolendronate 4 mg compared with pamidronate 90 mg. In the three studies of bisphosphonates in 320 women with advanced breast cancer without clinically evident bone metastases, there was no significant reduction in the incidence of skeletal events (RR 0.99; 95% CI 0.67-1.47; P = 0.97). In the three studies of oral clodronate that included 1653 women with early breast cancer, there was no statistically significant evidence of reduction in the risk of developing skeletal metastases (RR 0.82; 95% CI 0.66-1.01; P = 0.07), or of visceral metastases (RR 0.95; 95% CI 0.80-1.12, p = 0.53). However there was evidence of improved survival (RR 0.82; 95% CI 0.69-0.97, p = 0.02). However there was statistically significant heterogeneity among these studies and a random effects meta-analysis emphasizes the uncertainty of this finding (RR 0.75; 95% CI 0.45 - 1.25; p = 0.19). Toxicity or adverse events were described in 18 of the 21 studies. In general, few serious adverse events were reported. Toxicity associated with bisphosphonates is generally mild and infrequent. Renal toxicity is the main issue with intravenous zolendronate and is dose (8 mg) and infusion time related (< 15 minutes). With daily oral calcium (500 mg) and vitamin D (300-400IU) no significant renal impairment or hypocalcamia was observed with a 15 minute infusion of 4 mg IV zolendronate compared with 90 mg pamidronate. Monitoring of renal function with every cycle of zolendronate was undertaken in all studies and is recommended in practice. No significant renal toxicity was observed with intravenous pamidronate or ibandronate. Mild gastrointestinal toxicity is the main toxicity with oral clodronate and oral ibandronate.

AUTHORS' CONCLUSIONS

In women with advanced breast cancer and clinically evident bone metastases, the use of bisphosphonates (oral or intravenous) in addition to hormone therapy or chemotherapy, when compared with placebo or no bisphosphonates, reduces the risk of developing a skeletal event and the skeletal event rate, as well as increasing the time to skeletal event. Some bisphosphonates may also reduce bone pain in women with advanced breast cancer and clinically evident bone metastases and may improve global quality of life. The optimal timing of initiation of bisphosphonate therapy and duration of treatment is uncertain. In women with early breast cancer the effectiveness of bisphosphonates remains an open question for research.

Safety of Long-Term Administration of Bisphosphonates in Elderly Cancer Patients

BACKGROUND

To evaluate the effectiveness and tolerability of the long-term treatment bone metastases with pamidronate in older patients.

MATERIALS AND METHODS

Twenty-two ambulatory patients aged 70 or older were included in the study. The median age was 73 (range 70-77). Ten patients (46%) were affected by breast carcinoma, 7 (32%) by prostate carcinoma and 5 (22%) by multiple myeloma. Nine (40%) patients presented co-morbidity. All of the patients presented at least one metastatic lytic bone lesion measuring 1 cm or more in diameter; the median lesion number was 2 (range 1-4). Hormonal therapy or chemotherapy regimen, were allowed as clinically required. Patients were treated with a fixed dose of sodium pamidronate, 90 mg in 3 h infusion every 4 weeks.

RESULTS

Partial response was shown in 6 (28%) patients, stable disease in 11 (50%), and progression (PD) in 5 (22%). 2 out of 5 patients with PD presented skeletal-related events (SREs) such as bone fracture. The median treatment duration was 19 months. The treatment was well tolerated; in 5 patients (23%) a GI fever was observed, in 3 patients (18%) G1 nausea, and in 3 patients (14) G1 diarrhea. Two cases (9%) of acute renal insufficiency (creatinine 1.7 and 1.6 mg/dl), and 3 cases (14%) of hypocalcemia (7.6, 7.5 and 7.8 mg/dl) were also registered. The renal dysfunction was reversible and without consequence.

CONCLUSION

Our experience suggests that the bisphosphonates long-term administration is useful and did not cause significant side effects in elderly subjects. Low-grade pyrexia, nausea/vomiting, acute/reversible renal dysfunction and hypo-calcemia were the most frequent side effects reported. However, they were of low grade and in most cases, did not require dose modifications and/or hospitalization.

Duration of bisphosphonate treatment: results of a non-randomised study in patients previously treated with local irradiation for bone metastases from breast cancer

PURPOSE

To assess whether disodium pamidronate (DP) once started should be given life-long in women with lytic bone metastases.

PATIENTS AND METHODS

One hundred and three women with breast cancer who had at least one osteolytic lesion received 180 mg of DP as a 2-h intravenous infusion given every 4 weeks for a life-time, following local radiotherapy. After six cycles, 26 out of 103 patients (25%) refused to continue their bisphosphonate-treatment. Thus two groups were constituted: non-stop (group A) and premature discontinued (group B). The new skeletal complication free survival (NSCFS) was the primary endpoint verified during extramural review. Performance status, pain-score and biochemical markers were secondary endpoints.

RESULTS

Generally DP was well tolerated. At 36 months, the proportion of patients having had any skeletal complication was 54.5 and 84.6% in group A and B, respectively. The median time of NSCFS was apparently longer for group A. In group A, the pain score and the ECOG status were significantly lower, while the overall survival appeared to be longer. Multivariate analysis revealed age, nodal status and interruption of treatment as prognostic factors to NSCFS, with relative risk 1.05, 2.3 and 1.5 respectively.

CONCLUSION

Data concerning the suspension of new skeletal complications, as well as the apparent improvement of overall survival, pain score and ECOG status, suggest that the pamidronate-treatment should not be stopped once started. These results should be confirmed in a randomised trial.

Bilateral Acrometastasis Secondary to Breast Cancer

BACKGROUND

One out of every 8 women will be diagnosed with breast cancer and 1 in 28 will succumb to the disease. Skeletal metastasis occurs in 16% to 73% of breast cancer patients.

OBJECTIVE

To present a comprehensive look at the pathophysiology, clinical presentation, and treatment options for skeletal metastasis secondary to breast carcinoma by discussing the case of an 80-year-old female patient with bilateral distal lower extremity metastasis following a previous diagnosis of breast cancer.

CLINICAL FEATURES

The patient had severe pain in both lower extremities, which caused her to have difficulty when ambulating. She also complained of fatigue and anorexia, with an 8-lb weight loss. Chest examination revealed widespread rales without change. Her left calcaneus was tender to palpation and both feet and ankles were hot and swollen. Laboratory CA 27.29 values were 1131 on October 16, 2001, which was elevated compared with the 454 value obtained previously. Plain films of the lower extremities revealed destructive lesions of the distal left and right tibia and fibula with involvement of the left calcaneus. These findings were most consistent with metastasis.

INTERVENTION AND OUTCOME

The patient refused further care and sought a hospice referral.

CONCLUSION

There is no cure for acrometastasis and prognosis is poor. Treatment focuses on symptomatic relief, extended survival, and maintaining quality of life. Clinicians should consider metastasis in a patient with distal lower extremity osteolytic lesions with a previous history of breast malignancy.

Parathyroid hormone-related protein (PTHrP) is responsible for production of bone metastasis, but not visceral metastasis, by human small cell lung cancer SBC-5 cells in natural killer cell-depleted SCID mice

We previously established an osteolytic bone metastasis model with multiorgan dissemination in natural killer (NK) cell-depleted severe combined immunodeficient (SCID) mice using human small cell lung cancer cells (SBC-5), which highly express the parathyroid hormone-related protein (PTHrP). In our present study, we evaluated the role of PTHrP on bone metastasis by SBC-5 cells using anti-PTHrP neutralizing antibody (Ab). Anti-PTHrP Ab did not affect the proliferation or cytokine production of SBC-5 cells in vitro. Repeated intravenous injection with anti-PTHrP Ab inhibited the formation of bone metastasis in a dose-dependent manner, while the same treatment had no significant effect on the metastasis to visceral organs (lung, liver, kidney and lymph node). In addition, treatment with anti-PTHrP Ab improved the elevated serum calcium level, associated with inhibition of osteolytic bone metastasis, suggesting that anti-PTHrP Ab inhibited bone metastasis via suppression of bone resorption probably by neutralizing PTHrP. These findings suggest that PTHrP is essential for bone metastasis, but not visceral metastasis, by small cell lung cancer SBC-5 cells.

Inhibition of alpha(v)beta3 integrin reduces angiogenesis, bone turnover, and tumor cell proliferation in experimental prostate cancer bone metastases

The growth of metastatic prostate cancer cells in the bone involves an intimate interaction between the tumor cells and various elements of the bone microenvironment, resulting in increased rate of bone turnover and rapid tumor growth. The alpha(v)beta3 integrin has been shown to play an important role in tumor growth and angiogenesis, and is known to be critical to osteoclast formation and activity. This study was designed to examine the role of alpha(v)beta3 expressed by cells native to the bone in the growth and pathogenesis of prostate cancer bone metastases. Human prostate cancer cells which do not express alpha(v)beta3 or alpha(IIb)beta3 integrins were injected directly into human bone fragments previously implanted subcutaneously in SCID mice (SCID-human-bone model). At the same time treatment with anti-beta3 antibody fragment (m7E3 F(ab')2) i.p. at 300 microg/dose 3 x per week was initiated and continued for 2 weeks. In this system, m7E3 F(ab')2 only recognizes human bone-derived alpha(v)beta3. Antibody inhibition of alpha(v)beta3 integrin in vivo resulted in a specific reduction in the proportion of antigenically-human blood vessels within tumor-bearing bone implants (from 73.5% +/- 3.93 in controls to 17.74% +/- 5.64 in treated animals). Proliferation of the alpha(v)beta3-negative tumor cells was also reduced, although the overall vessel density was maintained by compensating mouse vasculature. Blockage of human bone-derived alpha(v)beta3 also significantly reduced the recruitment of osteoclasts in response to tumor cells, as well as degradation of calcified bone tissue. Together these observations confirm the importance of alpha(v)beta3 in bone metabolism and angiogenesis, and point to the role of these processes in controlling growth of metastatic prostate cancer cells in the bone.

Interpreting the molecular biology and clinical behavior of multiple myeloma in the context of global gene expression profiling

Multiple myeloma (MM) is a rare but uniformly fatal malignancy of antibody-secreting plasma cells (PCs). Although several key molecular events in disease initiation or progression have been confirmed (e.g. FGFR3/MMSET activation) or implicated (e.g. chromosome 13 deletion), the mechanisms of MM development remain enigmatic. Importantly, although generally being indistinguishable morphologically, MM exhibits a tremendous degree of variability in clinical course, with some patients surviving only months and others many years. However, current laboratory parameters can account for no more than 20% of this outcome variability. Furthermore, the means by which current drugs impart their anti-MM effect are also mostly unknown. In addition, the mechanisms by which MM cells contribute to serious comorbidities, such as osteopenia and/or focal lytic lesions of bone, are also poorly understood. Finally, very little knowledge exists concerning the molecular events leading to benign hyperplasia and/or overt malignancy of PCs. Given that abnormal gene expression lies at the heart of most, if not all, cancers, high-throughput global gene expression profiling has become a powerful tool for investigating molecular biology and clinical behavior of diseases. Here, we discuss recent progress made in addressing many of the above issues through the molecular dissection of the transcriptome of normal PCs and MM.

Bisphosphonates antagonise bone growth factors' effects on human breast cancer cells survival

Bone tissue constitutes a fertile 'soil' for metastatic tumours, notably breast cancer. High concentrations of growth factors in bone matrix favour cancer cell proliferation and survival, and a vicious cycle settles between bone matrix, osteoclasts and cancer cells. Classically, bisphosphonates interrupt this vicious cycle by inhibiting osteoclast-mediated bone resorption. We and others recently reported that bisphosphonates can also induce human breast cancer cell death in vitro, which could contribute to their beneficial clinical effects. We hypothesised that bisphosphonates could inhibit the favourable effects of 'bone-derived' growth factors, and indeed found that bisphosphonates reduced or abolished the stimulatory effects of growth factors (IGFs, FGF-2) on MCF-7 and T47D cell proliferation and inhibited their protective effects on apoptotic cell death in vitro under serum-free conditions. This could happen through an interaction with growth factors' intracellular phosphorylation transduction pathways, such as ERK1/2-MAPK. In conclusion, we report that bisphosphonates antagonised the stimulatory effects of growth factors on human breast cancer cell survival and reduced their protective effects against apoptotic cell death. Bisphosphonates and growth factors thus appear to be concurrent compounds for tumour cell growth and survival in bone tissue. This could represent a new mechanism of action of bisphosphonates in their protective effects against breast cancer-induced osteolysis.

Immunohistochemical study of receptor activator of nuclear factor kappa-B ligand (RANK-L) in human osteolytic bone tumors

BACKGROUND AND OBJECTIVES

Osteolytic bone tumors produce intercellular signaling proteins that regulate bone remodeling by altering the rates of osteoclast and osteoblast differentiation and activity. This report examines osteolytic bone tumor expression of receptor activator of nuclear factor B-ligand (RANK-L), a cytokine that is arguably the most critical regulator of osteoclast differentiation and activation.

METHODS

This prospective immunohistochemical study examined RANK-L expression in frozen tissues from sixteen surgical specimens of patients who underwent surgery for the treatment of osteolytic bone tumors between 1999 and 2000.

RESULTS

RANK-L was positive in 13 of the 16 cases. Primary benign bone tumors, primary malignant bone tumors, and metastasis to bone were positive for RANK-L.

CONCLUSIONS

The cells in some, but not all, osteolytic tumors produce the cytokine RANK-L. Further study is necessary to determine in which specific tumors RANK-L is the cytokine responsible for increased osteoclastic activity, and to develop possible therapeutic use of RANK-L antagonists such as osteoprotegerin (OPG).

Direct effects of bisphosphonates on breast cancer cells

In addition to inhibiting bone resorption, bisphosphonates have also been shown to exhibit antitumour effects. In vitro, bisphosphonates inhibit proliferation and induce apoptosis in cultured human breast cancer cells. In addition, bisphosphonate treatment interferes with breast cancer cell adhesion to bone matrix, and inhibits cell migration and invasion. The combination of bisphosphonates with other anticancer drugs such as the taxoids markedly enhances these effects. These newly recognized direct actions of bisphosphonates on breast cancer cells indicate that these agents may have a greater role to play in treatment of patients suffering from cancers with a propensity to metastasize to bone.

Bisphosphonates for breast cancer

BACKGROUND

Bone is the most common site of metastatic disease associated with breast cancer, and affects more than half of women during the course of their disease. Bone metastases are a significant cause of morbidity due to pain, pathological fractures, hypercalcaemia and spinal cord compression, and contribute to mortality. Bisphosphonates, which inhibit osteoclast-mediated bone resorption, are standard care for tumour-associated hypercalcaemia, and have been shown to reduce bone pain, improve quality of life, and to delay skeletal events and reduce their number in patients with multiple myeloma. Several randomized controlled trials have evaluated the role of bisphosphonates in breast cancer.

OBJECTIVES

The aim of this systematic review was to identify, describe and summarize high-quality evidence regarding the effect of bisphosphonates on skeletal events, bone pain, quality of life and survival in women with early and advanced breast cancer.

SEARCH STRATEGY

Randomized controlled trials were identified in the specialized register maintained by the secretariat of the Cochrane Breast Cancer Group (the search was applied to the databases Medline, Central/CCTR, Embase, CancerLit, and included handsearches from a number of other relevant sources). See: Cochrane Collaboration Collaborative Review Group in Breast Cancer search strategy.

SELECTION CRITERIA

Randomized controlled trials evaluating skeletal events in women with metastatic breast cancer and in women with early breast cancer comparing: 1. treatment with a bisphosphonate with the same treatment without a bisphosphonate 2. treatment with one bisphosphonate with treatment with a different bisphosphonate.

DATA COLLECTION AND ANALYSIS

Studies were selected by two independent reviewers. Studies fulfilling the eligibility criteria were evaluated for quality, particularly concealment of allocation to randomized groups. Data were extracted from the published papers or abstracts independently by the two primary reviewers for each of the specified endpoints (skeletal events, bone pain, quality of life and survival). Data on skeletal events and survival were presented as numbers of events, risk ratios and ratios of event rates. Meta-analyses were based on the fixed-effects model (Mantel-Haenszel). Subjective qualitative ratings were used to summarize the quality of life and pain data.

MAIN RESULTS

From 37 reports considered in detail after screening of the 117 reports identified by our search, 19 randomized studies were included. In eight studies that included 1962 women with advanced breast cancer and existing bone metastases, bisphosphonates reduced the risk of developing a skeletal event by 14% (RR 0.86; 95% confidence interval (CI) 0.80-0.91; P < 0.00001). This effect was more modest, but still highly significant if episodes of hypercalcaemia were excluded (6 studies, 1553 women, RR 0.88; 95% CI 0.81-0.96; P = 0.004). For intravenous pamidronate the reduction in the risk of skeletal event was greatest with a dosage of 90 mg (RR 0.77; 95% CI 0.69-0.87). Oral bisphosphonates reduced the risk of a skeletal event by 17% (pooled RR 0.83; 95% CI 0.73-0.94, P = 0.004). Oral clodronate reduced the risk of a skeletal event by 16% in women with advanced breast cancer and clinically evident bone metastases (pooled RR 0.84; 95% CI 0.72-0.98; P = 0.03). Compared with placebo or no bisphosphonate, with bisphosphonates the skeletal event rate was lower in all of eight studies (median reduction of 30%, range 20-48%); statistically significant reductions were reported in six trials (three intravenous pamidronate, two oral clodronate and one intravenous ibandronate). All studies of intravenous pamidronate and oral clodronate in women with advanced breast cancer and clinically evident bone metastases showed significant delays in the median time to a skeletal event. Event-free survival was reported to be longer in women receiving 6 mg of ibandronate compared with control women. Compared with placebo or no bisphosphonate, with bisphosphonates significant improvements in pain were reported in four studies, and improvements in quality of life were reported in two studies. Treatment with bisphosphonates does not appear to affect survival in women with advanced breast cancer. Intravenous zolendronate (4 mg) appeared to have equivalent efficacy when compared with intravenous pamidronate in a single randomized double-blind study. In the three studies of bisphosphonates in 320 women with advanced breast cancer without clinically evident bone metastases, there was no significant reduction in the incidence of skeletal events (RR 0.99; 95% CI 0.67-1.47; P > 0.9). In three studies of oral clodronate that included 1680 women with early breast cancer, there was borderline evidence of a reduction in the risk of developing skeletal metastases (RR 0.73; 95% CI 0.55-0.98; P = 0.04), but there was significant heterogeneity among these studies (P = 0.035). Toxicity or adverse events were described in 14 of the 19 studies. In general, few adverse events were reported.

REVIEWER'S CONCLUSIONS

In women with advanced breast cancer and clinically evident bone metastases, the use of bisphosphonates (oral or intravenous) in addition to hormone therapy or chemotherapy, when compared with placebo or no bisphosphonates, reduces the risk of developing a skeletal event and the skeletal event rate, as well as increasing the time toskeletal event. Bisphosphonates may also reduce bone pain in women with advanced breast cancer and clinically evident bone metastases. In women with early breast cancer the effectiveness of oral clodronate in reducing the incidence of bone metastases remains an open question for research.

Novel therapeutic approaches to cancer patients with bone metastasis

Bone metastases are a common event in advanced cancer. Breast, lung, prostate and thyroid neoplasms have striking osteotropism. Bone metastatic cancer may be associated with catastrophic consequences for the patients. Therefore, new strategies are warranted in order to reduce the incidence of bone metastases and to palliative established skeletal disease. External beam radiation therapy, endocrine treatments, chemotherapy, bisphosphonates and radioisotopes are all important. Bisphosphonates have become the treatment of choice for tumor-induced hypercalcaemia and more recently they have been used alone or in combination with cytotoxic agents in the palliative treatment of patients with bone metastases. The results are encouraging. Currently, new bisphosphonates that are a hundred times more powerful with respect to clodronate and pamidronate are under investigation. The treatment of metastases to bone and mechanisms of pain relief after radiation therapy are poorly understood. Up to date, there are not standard criteria for the irradiation of bone metastases and bone pain relief may be reached using a variety of fractionation schemes. Radionuclide therapy is the systemic use of radioisotopes for bone pain. It is currently regarded as suitable for comparison with wide-field irradiation, but appears to have major disadvantages in terms of pain relief and toxicity.

Breast cancer cells release factors that induced apoptosis in human bone marrow stromal cells

Breast cancer is associated frequently with skeletal metastases, which cause significant morbidity. The main mechanism is an increase in osteoclast-mediated bone resorption. We postulated that osteoblasts could be other essential target cells and previously showed that conditioned medium (CM) of breast cancer cells (BCCs) inhibits the proliferation of osteoblast-like cells. In this study, we investigated the effects of BCC-secreted products on osteoprogenitor cells using a clonal fetal human bone marrow stromal preosteoblastic cell line (FHSO-6) that expresses alkaline phosphatase (ALP) activity, type I collagen (COLI), and increased osteocalcin (OC) and osteopontin under treatment with dexamethasone (Dex), 1,25-dihydroxyvitamin D [1,25(OH)2D], or recombinant human bone morphogenetic protein 2 (rhBMP-2). Treatment with MCF-7 CM inhibited FHSO-6 cell survival in a dose-dependent and irreversible manner. Morphological investigation indicated that MCF-7 CM increased both apoptotic and necrotic cell number. MCF-7 CM increased caspases activity and a broad inhibitor of caspase activity (benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethyl ketone [z-VAD-fmk]) partly reversed the CM-induced inhibition of FHSO-6 cell survival. Western blot analyses revealed an increased bax/bcl-2 ratio in MCF-7 CM-treated FHSO-6 cells. MCF-7 cells exhibit FasLigand as membrane-bound protein and as a soluble cytokine in the CM. Deprivation of MCF-7 CM from active FasLigand by saturation with a soluble Fas molecule suppressed the induction of FHSO-6 apoptosis, whereas fibroblast CM, which did not contain FasLigand, only weakly modified FHSO-6 cell survival because of increased cell necrosis. These data indicate that FasLigand secreted by BCCs induces apoptosis and necrosis of human preosteoblastic stromal cells through caspase cascade modulated by the bax and bcl-2 protein level. The induction of apoptosis in human bone marrow stromal cells by BCCs may contribute to the inappropriately low osteoblast reaction and bone formation during tumor-induced osteolysis in bone metastases.

International myeloma grand round

On the 14th June 2001, The Royal Marsden Hospital, London, hosted an unusual event, an international grand round, aimed at exploring a new concept in the treatment of multiple myeloma--operational cure. The speakers were Jean-Luc Harousseau (France), Gregory Mundy (USA), Brian Durie (USA) and Ray Powles (UK). Case histories were presented by Bhawna Sirohi (UK). The 80 invited guests included oncologists, radiotherapists, histopathologists, representatives of the International Myeloma Foundation, members of the press, and several myeloma patients, including the two whose case histories are presented below.