The backbone of progress--preclinical studies and innovations with zoledronic acid

Macrophages: Key Players in the Battle against Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a challenging subtype of breast cancer characterized by the absence of estrogen and progesterone receptors and HER2 expression, leading to limited treatment options and a poorer prognosis. TNBC is particularly prevalent in premenopausal African-descent women and is associated with aggressive tumor behavior and higher metastatic potential. Tumor-associated macrophages (TAMs) are abundantly present within the TNBC microenvironment and play pivotal roles in promoting tumor growth, progression, and metastasis through various mechanisms, including immune suppression and enhancement of angiogenesis. This review provides an in-depth overview of TNBC, focusing on its epidemiology, its molecular characteristics, and the critical influence of TAMs. It discusses the pathological and molecular aspects that define TNBC's aggressive nature and reviews current and emerging therapeutic strategies aimed at targeting these dynamics. Special attention is given to the role of TAMs, exploring their potential as therapeutic targets due to their significant impact on tumor behavior and patient outcomes. This review aims to highlight the complexities of the TNBC landscape and to present the innovative approaches that are currently being pursued to improve therapeutic efficacy and patient survival.

The Impact of Obesity, Adipose Tissue, and Tumor Microenvironment on Macrophage Polarization and Metastasis

Tumor metastasis is a major cause of death in cancer patients. It involves not only the intrinsic alterations within tumor cells, but also crosstalk between these cells and components of the tumor microenvironment (TME). Tumorigenesis is a complex and dynamic process, involving the following three main stages: initiation, progression, and metastasis. The transition between these stages depends on the changes within the extracellular matrix (ECM), in which tumor and stromal cells reside. This matrix, under the effect of growth factors, cytokines, and adipokines, can be morphologically altered, degraded, or reorganized. Many cancers evolve to form an immunosuppressive TME locally and create a pre-metastatic niche in other tissue sites. TME and pre-metastatic niches include myofibroblasts, immuno-inflammatory cells (macrophages), adipocytes, blood, and lymphatic vascular networks. Several studies have highlighted the adipocyte-macrophage interaction as a key driver of cancer progression and dissemination. The following two main classes of macrophages are distinguished: M1 (pro-inflammatory/anti-tumor) and M2 (anti-inflammatory/pro-tumor). These cells exhibit distinct microenvironment-dependent phenotypes that can promote or inhibit metastasis. On the other hand, obesity in cancer patients has been linked to a poor prognosis. In this regard, tumor-associated adipocytes modulate TME through the secretion of inflammatory mediators, which modulate and recruit tumor-associated macrophages (TAM). Hereby, this review describes the cellular and molecular mechanisms that link inflammation, obesity, and cancer. It provides a comprehensive overview of adipocytes and macrophages in the ECM as they control cancer initiation, progression, and invasion. In addition, it addresses the mechanisms of tumor anchoring and recruitment for M1, M2, and TAM macrophages, specifically highlighting their origin, classification, polarization, and regulatory networks, as well as their roles in the regulation of angiogenesis, invasion, metastasis, and immunosuppression, specifically highlighting the role of adipocytes in this process.

Zoledronate upregulates MMP-9 and -13 in rat vascular smooth muscle cells by inducing oxidative stress

Background

Bisphosphonates, including zoledronate, target osteoclasts and are widely used in the treatment of osteoporosis and other bone resorption diseases, despite side effects that include damaging the stomach epithelium. Beneficial and adverse effects on other organ systems, including the cardiovascular system, have also been described and could impact on the use of bisphosphonates as therapeutic agents. Vascular smooth muscle cells (VSMCs) are major constituents of the normal vascular wall and have a key role in intimal thickening and atherosclerosis, in part by secreting MMPs that remodel the extracellular matrix and cleave cell surface proteins or secreted mediators. In this study, we investigated the effects of zoledronate on MMP expression.

Methods

Rat VSMCs were stimulated by PDGF (50 ng/mL) plus TNF-α (10 ng/mL) or left unstimulated for a further 24 hours in serum-free medium. In other series of experiments, cells were pre-treated either with SC-514 (50 μM) or with apocynin (20 nM) for 2 hours, then zoledronate (100 μM) was added into 2% fetal calf serum containing medium for 24 hours.

Results and discussion

Using isolated rat VSMCs in culture, zoledronate (100 μM) increased MMP-9 and -13 mRNA expressions but inhibited MMP-2 expression. MMP-9 and MMP-13 up-regulation was shown to depend on the NF-κB pathway; and this was activated by zoledronate. Furthermore, zoledronate elevated the levels of reactive oxygen species detected by either dichlorofluorescein in isolated VSMCs or lucigenin enhanced chemiluminescence in rat aortic rings in vitro. Apocynin, an inhibitor of NADPH oxidase, reversed NF-κB activation and MMP-9 and MMP-13 up-regulation by zoledronate.

Conclusion

We conclude that zoledronate increases MMP-9 and MMP-13 expressions in rat VSMCs dependent upon stimulation of the NF-κB pathway by reactive oxygen species. Effects on MMP expression may contribute to the pharmacologic profile of bisphosphonates.

Basal and therapy-driven hypoxia-inducible factor-1α confers resistance to endocrine therapy in estrogen receptor-positive breast cancer

Resistance is an obstacle to endocrine therapy for breast cancer. We measured levels of hypoxia-inducible factor (HIF)-1α in 52 primary breast cancer patients before and after receiving neoadjuvant endocrine therapy with letrozole for at least 3 months. Pre-treatment levels of HIF-1α were associated with negative clinical outcome. Furthermore, levels of HIF-1α were increased in post-treatment residual tumors compared with those in pre-treatment biopsy samples. In animal studies, xenografts stably expressing HIF-1α were resistant to endocrine therapy with fulvestrant compared with the effects in control xenografts. Additionally, HIF-1α transcription was inhibited by zoledronic acid, a conventional drug for the treatment of postmenopausal osteoporosis, and was accompanied by a marked inhibition of the RAS/MAPK/ERK1/2 pathway. HIF-1α is a determinant of resistance to endocrine therapy and should be considered as a potential therapeutic target for overcoming endocrine resistance in estrogen receptor (ER)-positive breast cancer. In addition, zoledronic acid may overcome endocrine resistance in ER-positive human breast cancer by targeting HIF-1α transcription through inhibition of the RAS/MAPK/ERK1/2 pathway. Clinical studies on the administration of zoledronic acid as a second line treatment in patients who failed endocrine therapy should be considered to improve therapeutic outcomes in breast cancer patients.

Randomized Controlled Trial of Zoledronic Acid plus Chemotherapy versus Chemotherapy Alone as Neoadjuvant Treatment of HER2-Negative Primary Breast Cancer (JONIE Study)

Purpose

Zoledronic acid (ZOL) is a nitrogen-containing bisphosphonate that induces osteoclast apoptosis and inhibits bone resorption by inhibiting the mevalonate pathway. Its benefit for the prevention of skeletal complications due to bone metastases has been established. However, the antitumor efficacy of ZOL, although suggested by multiple preclinical and clinical studies, has not yet been clinically proven. We performed the present randomized Phase 2 trial to investigate the antitumor effect of ZOL with chemotherapy (CT).

Methods

Asian patients with HER2-negative invasive breast cancer were randomly assigned to either the CT or CT+ZOL (CTZ) group. One hundred and eighty-eight patients were randomized to either the CT group (n = 95) or the CTZ group (n = 93) from March 2010 to April 2012, and 180 patients were assessed. All patients received four cycles of FEC100 (fluorouracil 500 mg/m², epirubicin 100 mg/m², and cyclophosphamide 500 mg/m²), followed by 12 cycles of paclitaxel at 80 mg/m² weekly. ZOL (4 mg) was administered three to four times weekly for 7 weeks to the patients in the CTZ group. The primary endpoint was the pathological complete response (pCR) rate, which was defined as no invasive cancer in the breast tissue specimen. Safety was assessed in all patients who received at least one dose of the study drug.

Results

This randomized controlled trial indicated that the rates of pCR in CTZ group (14.8%) was doubled to CT group (7.7%), respectively (one-sided chi-square test, p = 0.068), though the additional efficacy of zoledronic acid was not demonstrated statistically. The pCR rate in postmenopausal patients was 18.4% and 5.1% in the CTZ and CT groups, respectively (one-sided Fisher’s exact test, p = 0.071), and that in patients with triple-negative breast cancer was 35.3% and 11.8% in the CTZ and CT groups, respectively (one-sided Fisher’s exact test, p = 0.112). Thus the addition of ZOL to neoadjuvant CT has potential anticancer benefits in postmenopausal patients and patients with triple-negative breast cancer. Further investigation is warranted.

Trial Registration

University Hospital Medical Information Network. UMIN000003261.

Oestrogen receptor positive breast cancer metastasis to bone: inhibition by targeting the bone microenvironment in vivo

Clinical trials have shown that adjuvant Zoledronic acid (ZOL) reduces the development of bone metastases irrespective of ER status. However, post-menopausal patients show anti-tumour benefit with ZOL whereas pre-menopausal patients do not. Here we have developed in vivo models of spontaneous ER+ve breast cancer metastasis to bone and investigated the effects of ZOL and oestrogen on tumour cell dissemination and growth. ER+ve (MCF7, T47D) or ER-ve (MDA-MB-231) cells were administered by inter-mammary or inter-cardiac injection into female nude mice ± estradiol. Mice were administered saline or 100 μg/kg ZOL weekly. Tumour growth, dissemination of tumour cells in blood, bone and bone turnover were monitored by luciferase imaging, histology, flow cytometry, two-photon microscopy, micro-CT and TRAP/P1NP ELISA. Estradiol induced metastasis of ER+ve cells to bone in 80-100 % of animals whereas bone metastases from ER-ve cells were unaffected. Administration of ZOL had no effect on tumour growth in the fat pad but significantly inhibited dissemination of ER+ve tumour cells to bone and frequency of bone metastasis. Estradiol and ZOL increased bone volume via different mechanisms: Estradiol increased activity of bone forming osteoblasts whereas administration of ZOL to estradiol supplemented mice decreased osteoclast activity and returned osteoblast activity to levels comparable to that of saline treated mice. ER-ve cells require increased osteoclast activity to grow in bone whereas ER+ve cells do not. Zol does not affect ER+ve tumour growth in soft tissue, however, inhibition of bone turnover by ZOL reduced dissemination and growth of ER+ve breast cancer cells in bone.

Bisphosphonates in adjuvant setting for breast cancer: a review of the meta-analysis of bisphosphonates' effects on breast cancer recurrence presented in December 2013 at San Antonio Breast Conference

PURPOSE OF REVIEW

Bisphosphonate therapy has been used as standard of care for patients with metastatic bone disease. As bisphosphonate had demonstrated antitumor effects in preclinical studies, it was natural to advance to the development of large phase 3 trials that would test the activity of bisphosphonate in the adjuvant setting. Surprisingly, the results of adjuvant breast cancer trials have shown either modest or contradictory effects. One of the most consistent results across the latest reports on this issue is that bisphosphonate shows benefit in the prevention of distant relapses in breast cancer women after menopause, but not before. We sought to comment on the most recent studies and to reflect on the possible practical recommendations for the use of bisphosphonate in this setting.

RECENT FINDINGS

In the last San Antonio Breast Cancer Conference, the Early Breast Cancer Trialists' Collaborative Group's Bisphosphonate Working Group presented a meta-analysis of individual patient data from randomized trials. The main conclusions of this presentation were that all bisphosphonates (not only nitrogen-containing bisphosphonates) can decrease bone recurrence in postmenopausal women with early breast cancer.

SUMMARY

The benefit of bisphosphonate use in an adjuvant setting is significant only in postmenopausal women. Further investigation into factors influencing the response to bisphosphonate treatment is needed.

Myelosuppressive therapies significantly increase pro-inflammatory cytokines and directly cause bone loss

Skeletal-related events resulting from accelerated bone loss are common complications in patients treated for a range of cancers. However, the mechanisms and rate of bone loss after myelosuppression are unclear. We, therefore, investigated this in mice and humans. We treated mice with different myelosuppressive therapies (chemotherapy or irradiation with or without transplantation) and studied their effects on bone structure. Myelosuppression of mice rapidly caused an increase in bone resorption that was not matched by bone formation. The resultant significant and persistent bone loss early after therapy was associated with increased inflammatory cytokines, in particular, monocyte chemoattractant protein 1 (MCP1). Therapy-induced bone loss was prevented with a single dose of the bisphosphonate zoledronic acid (ZA), administered before myelosuppression. Importantly, ZA treatment of mice did not impair hematopoiesis, including hematopoietic stem cell function. Furthermore, examination of serum from patients before and after autologous or allogeneic stem cell transplantion (SCT) revealed altered levels of bone turnover markers and elevated inflammatory cytokines. MCP1 levels in serum obtained between days 7 and 14 post-SCT positively correlated with bone loss observed at 100 days after allogeneic SCT. Similar to that observed in our studies in mice, the bone loss was long term, persisting at 12 months post-SCT. Furthermore, patients who received chemotherapy less than 100 days before SCT had significantly more bone loss at the hip. In these patients, serum levels of MCP1, but not routine biomarkers of bone turnover, including C-terminal cross-linking telopeptide of type-1 collagen (β-CTx), positively correlated with their bone loss. Hence, myelosuppressive therapies increase inflammation and directly contribute to bone loss. Administration of an osteoclast inhibitor before the initiation of cancer therapy is likely to have the best outcome in preventing bone loss in patients with cancer.

Effects of zoledronic acid and the association between its efficacy and γδT cells in postmenopausal women with breast cancer treated with preoperative hormonal therapy: a study protocol

BACKGROUND

Although the efficacy of zoledronic acid in postmenopausal women with breast cancer has been suggested, the underlying mechanism has not been fully clarified. Therefore, which patients may benefit from zoledronic acid and the optimal frequency of zoledronic acid administration are unclear. This study evaluates the effects of zoledronic acid on the tumor response in postmenopausal women with breast cancer and explores the relationship between its efficacy and γδ T cells.

METHODS/DESIGN

This study is an open-label, multi-institutional, single-arm, phase II clinical trial. Zoledronic acid will be administered once during preoperative hormonal therapy with letrozole for 24 weeks in postmenopausal women with Estrogen Receptor (ER)-positive , Human Epidermal Growth Factor Receptor 2 (HER2)-negative, clinical T1 or T2 N0M0 breast cancer. The primary endpoint is the objective response rate measured by MRI at 12 and 24 weeks. The secondary endpoints are the associations between the frequency of Vγ2Vδ2 T cells before the administration of zoledronic acid and the objective response, the association between the frequency of Vγ2Vδ2 T cells and the Preoperative Endocrine Prognostic Index score, and the association between the frequency of Vγ2Vδ2 T cells and Ki67 (MIB-1 index).

DISCUSSION

This study is designed to determine the add-on effect of zoledronic acid during preoperative hormonal therapy and to investigate the changes of the frequency of Vγ2Vδ2 T cells after the administration of zoledronic acid to explore the potential mechanism of zoledronic acid in breast cancer patients.

TRIAL REGISTRATION

This trial was registered at the UMIN Clinical Trials Registry as UMIN000008701.

Low doses amino-bisphosphonates stimulate keratinocytes growth inactivating glucocorticoid receptor

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

The role of tumor-associated macrophages in breast cancer progression (review)

It is well established that the tumor microenvironment plays a major role in the aggressive behavior of malignant solid tumors. Among cell types associated with tumor microenvironment, tumor-associated macrophages (TAMs) are the most influential for tumor progression. Breast cancer is characterized by having a large population of TAMs, and experimental models have exposed multiple mechanisms by which TAMs interact with and influence the surrounding tumor cells. The process of metastasis involves tumor cells gaining access to the tissue outside the immediate tumor environment and invading the confining extracellular matrix (ECM). Supporting this process, TAMs secrete proangiogenic factors such as VEGF to build a network of vessels that provide nutrition for tumor cells, but also function as channels of transport into the ECM. Additionally, TAMs release factors to decrease the local pro-inflammatory antitumor response, suppressing it and providing a means of escape of the tumor cells. Similarly, hypoxia in the tumor microenvironment stimulates macrophages to further produce VEGF and suppress the T-cell immune responses, thus, enhancing the evasion of tumor cells and ultimately metastasis. Given the multiple roles of TAMS in breast cancer progression and metastasis, therapies targeting these cells are in development and demonstrate promising results.

Randomized clinical trial of zoledronic acid in multiple myeloma patients undergoing high-dose chemotherapy and stem-cell transplantation

BACKGROUND

A growing body of evidence is demonstrating that the nitrogen-containing bisphosphonate zoledronic acid (zol) improves clinical outcomes in various cancer settings, including multiple myeloma. Those findings provided the rationale for conducting an open-label randomized controlled phase iii trial to evaluate the effect of zol on overall survival (os) and progression-free survival (pfs) in patients with previously untreated high-risk multiple myeloma.

METHODS

The trial randomly assigned 308 adult patients less than 65 years of age with previously untreated symptomatic multiple myeloma (1:1) to receive zol 4 mg intravenously once every 28 days for 24 months (n = 151) or no zol (n = 157). Before autologous stem-cell transplantation (asct), all patients received a high-dose noncytotoxic induction regimen of dexamethasone, all-trans-retinoic acid, and interferon alpha 2b.

RESULTS

After a median follow-up of 69.8 months (range: 36.5-96 months), the 10-year pfs (66% vs. 52%, p < 0.001) and os (67% vs. 48%, p < 0.001) rates were significantly higher in treated patients than in control patients. Overall response (77% zol vs. 75% control), complete response (52% vs. 46%), and very good partial response (25% vs. 29%) rates were similar between the groups. Treatment was generally well tolerated, with no reports of renal impairment or osteonecrosis of the jaw.

CONCLUSIONS

In symptomatic previously untreated multiple myeloma patients, zol combined with high-dose therapy followed by asct improved os and pfs without appreciable toxicity. These findings provide additional evidence of the meaningful anticancer activity of zol in this patient population.

Mechanisms of the antitumor activity of human Vγ9Vδ2 T cells in combination with zoledronic acid in a preclinical model of neuroblastoma

Low expression of surface major histocompatibility complex (MHC) class I molecules and defects in antigen processing machinery make human neuroblastoma (NB) cells appropriate targets for MHC unrestricted immunotherapeutic approaches. Human T-cell receptor (TCR) Vγ9Vδ2 lymphocytes exert MHC-unrestricted antitumor activity and are activated by phosphoantigens, whose expression in cancer cells is increased by aminobisphosphonates. With this background, we have investigated the in vivo anti-NB activity of human Vγ9Vδ2 lymphocytes and zoledronic acid (ZOL). SH-SY-5Y human NB cells were injected in the adrenal gland of immunodeficient mice. After 3 days, mice received ZOL or human Vγ9Vδ2 T cells or both agents by intravenous administration once a week for 4 weeks. A significantly improved overall survival was observed in mice receiving Vγ9Vδ2 T cells in combination with ZOL. Inhibition of tumor cell proliferation, angiogenesis and lymphangiogenesis, and increased tumor cell apoptosis were detected. Vγ9Vδ2 T lymphocytes were attracted to NB-tumor masses of mice receiving ZOL where they actively modified tumor microenvironment by producing interferon-γ (IFN-γ), that in turn induced CXCL10 expression in NB cells. This study shows that human Vγ9Vδ2 T cells and ZOL in combination inhibit NB growth in vivo and may provide the rationale for a phase I clinical trial in patients with high-risk NB.

Anti-tumour strategies aiming to target tumour-associated macrophages

Tumour-associated macrophages (TAMs) represent a predominant population of inflammatory cells that present in solid tumours. TAMs are mostly characterized as alternatively activated M2-like macrophages and are known to orchestrate nearly all stages of tumour progression. Experimental investigations indicate that TAMs contribute to drug-resistance and radio-protective effects, and clinical evidence shows that an elevated number of TAMs and their M2 profile are correlated with therapy failure and poor prognosis in cancer patients. Recently, many studies on TAM-targeted strategies have made significant progress and some pilot works have achieved encouraging results. Among these, connections between some anti-tumour drugs and their influence on TAMs have been suggested. In this review, we will summarize recent advances in TAM-targeted strategies for tumour therapy. Based on the proposed mechanisms, those strategies are grouped into four categories: (i) inhibiting macrophage recruitment; (ii) suppressing TAM survival; (iii) enhancing M1-like tumoricidal activity of TAMs; (iv) blocking M2-like tumour-promoting activity of TAMs. It is desired that further attention be drawn to this research field and more effort be made to promote TAM-targeted tumour therapy.

Liposome encapsulation of zoledronic acid results in major changes in tissue distribution and increase in toxicity

BACKGROUND

Zoledronic acid (Zol) is a potent inhibitor of farnesyl-pyrophosphate synthase with broad clinical use in the treatment of osteoporosis, and bone metastases. We have previously shown that encapsulation of Zol in liposomes targeted to the folate receptor (FR) greatly enhances its in vitro cytotoxicity. To examine whether targeted liposomal delivery of Zol could be a useful therapeutic approach, we investigated here the in vivo pharmacology of i.v. administered liposomal Zol (L-Zol) in murine models.

METHODS

Zol was passively entrapped in the water phase of liposomes containing a small fraction of either dipalmitoyl-phosphatidylglycerol (DPPG) or a polyethylene-glycol (PEG)-conjugated phospholipid with or without insertion of a folate lipophilic conjugate. Radiolabeled formulations were used for pharmacokinetic (PK) and biodistribution studies. Toxicity was evaluated by clinical, hematological, biochemical, and histopathological parameters. Therapeutic studies comparing free Zol, nontargeted and folate targeted L-Zol were performed in FR-expressing human tumor models.

RESULTS

Encapsulation of Zol in liposomes resulted in major PK changes including sustained high plasma levels and very slow clearance. DPPG-L-Zol was cleared faster than PEG-L-Zol. Grafting of folate lipophilic conjugates on liposomes further accelerated the clearance of Zol. L-Zol caused a major shift in drug tissue distribution when compared to free Zol, with a major increase (20 to 100-fold) in liver and spleen, a substantial increase (7 to 10-fold) in tumor, and a modest increase (2-fold) in bone. Liposomal formulations proved to be highly toxic, up to 50-fold more than free Zol. PEG-L-Zol was more toxic than DPPG-L-Zol. Toxicity was non-cumulative and appears to involve macrophage/monocyte activation and release of cytokines. Co-injection of L-Zol with a large dose of blank liposomes, or injection of a very low Zol-to-phospholipid ratio liposome formulation reduced toxicity by 2-4-fold suggesting that diluting macrophage exposure below a threshold Zol concentration is important to overcome toxicity. L-Zol failed to significantly enhance the therapeutic activity of Zol vis-à-vis free ZOL and doxorubicin. Folate-targeted L-Zol was marginally better than other treatment modalities in the KB tumor model but toxic deaths greatly affected the outcome.

CONCLUSIONS

Liposome delivery of Zol causes a major change in tissue drug distribution and an increase in tumor Zol levels. However, the severe in vivo toxicity of L-Zol seriously limits its dose and its utility for in vivo tumor cell targeting. This strategy is under evaluation using liposomes carrying less toxic bisphosphonates.

Zoledronic acid (zoledronate) for postmenopausal women with early breast cancer receiving adjuvant letrozole (ZO-FAST study): final 60-month results

BACKGROUND

Aromatase inhibitors are the preferred adjuvant endocrine therapy for the majority of postmenopausal women with hormone-responsive early breast cancer. Although generally more effective than tamoxifen, aromatase inhibitor therapy is associated with increased bone loss and fracture risk.

PATIENTS AND METHODS

Postmenopausal women receiving adjuvant letrozole (2.5 mg/day for 5 years; N = 1065) were randomly assigned to immediate zoledronic acid (zoledronate) 4 mg every 6 months for 5 years, or delayed zoledronate (initiated for fracture or on-study bone mineral density [BMD] decrease). The primary end point was the change in lumbar spine BMD at 12 months. Lumbar spine and total hip BMD at subsequent follow-up, disease-free survival (DFS), and overall survival were assessed as secondary end points.

RESULTS

At 60 months (final analysis), the mean change in lumbar spine BMD was +4.3% with immediate zoledronate and -5.4% with delayed intervention (P < 0.0001). Immediate zoledronate reduced the risk of DFS events by 34% (hazard ratio [HR] = 0.66; P = 0.0375) with fewer local (0.9% versus 2.3%) and distant (5.5% versus 7.7%) recurrences versus delayed zoledronate. In the delayed group, delayed initiation of zoledronate substantially improved DFS versus no zoledronate (HR = 0.46; P = 0.0334).

CONCLUSIONS

Immediate zoledronate in postmenopausal women receiving letrozole preserved BMD and is associated with improved DFS compared with letrozole alone. Clinical Trials Registration No NCT00171340.

Importance of antiresorptive therapies for patients with bone metastases from solid tumors

Patients with bone metastases are at risk of skeletal-related events such as pathologic fractures, spinal cord compression, the need for orthopedic surgery to bone, and palliative radiotherapy for severe bone pain. Antiresorptive therapies have demonstrated efficacy for reducing the risk of skeletal-related events and ameliorating bone pain. Despite the well documented clinical benefits of antiresorptive therapies, patient benefits can be limited or compromised by nonadherence with scheduled therapy. Potential reasons for poor compliance include lack of understanding of how antiresorptive therapies work, neglecting the importance of bone health in maintaining quality of life, and being unaware of the potentially debilitating effects of skeletal-related events caused by bone metastases. Indeed, patients may stop therapy after bone pain subsides or discontinue due to generally mild and usually manageable adverse events, leaving them at an increased risk of developing skeletal-related events. In addition, the cost of antiresorptive therapy can be a concern for many patients with cancer. Medical care for patients with cancer requires a coordinated effort between primary care physicians and oncologists. Patients’ medical care teams can be leveraged to help educate them about the importance of adherence to antiresorptive therapy when cancer has metastasized to bone. Because primary care physicians generally have more contact with their patients than oncologists, they are in a unique position to understand patient perceptions and habits that may lead to noncompliance and to help educate patients about the benefits and risks of various antiresorptive therapies in the advanced cancer setting. Therefore, primary care physicians need to be aware of various mechanistic and clinical considerations regarding antiresorptive treatment options.

Parametric response mapping of CT images provides early detection of local bone loss in a rat model of osteoporosis

Loss of bone mass due to disease, such as osteoporosis and metastatic cancer to the bone, is a leading cause of orthopedic complications and hospitalization. Onset of bone loss resulting from disease increases the risk of incurring fractures and subsequent pain, increasing medical expenses while reducing quality of life. Although current standard CT-based protocols provide adequate prognostic information for assessing bone loss, many of the techniques for evaluating CT scans rely on measures based on whole-bone summary statistics. This reduces the sensitivity at identifying local regions of bone resorption, as well as formation. In this study, we evaluate the effectiveness of a voxel-based image post-processing technique, called the Parametric Response Map (PRM), for identifying local changes in bone mass in weight-bearing bones on CT scans using an established animal model of osteoporosis. Serial CT scans were evaluated weekly using PRM subsequent to ovariectomy or sham surgeries over the period of one month. For comparison, bone volume fraction and mineral density measurements were acquired and found to significantly differ between groups starting 3 weeks post-surgery. High resolution ex vivo measurements acquired four weeks post-surgery validated the extent of bone loss in the surgical groups. In contrast to standard methodologies for assessing bone loss, PRM results were capable of identifying local decreases in bone mineral by week 2, which were found to be significant between groups. This study concludes that PRM is able to detect changes in bone mineral with higher sensitivity and spatial differentiation than conventional techniques for evaluating CT scans, which may aid in clinical decision making for patients suffering from bone loss.

Zoledronic acid in the treatment of early-stage breast cancer: is there a final verdict?

Breast cancer, which preferentially metastasizes to bone, is the most common malignancy among women worldwide and is a leading cause of death. Clinical data from large, phase 3 trials (ie, ABCSG-12, ZO-FAST, and AZURE) demonstrate significantly improved disease-free survival with zoledronic acid in some patient populations with early breast cancer. Although the interim results from the AZURE trial did not show a disease-free survival benefit with zoledronic acid in the overall patient population, subset analyses showed that zoledronic acid significantly improved disease-free survival in women with established postmenopausal status at baseline. Similarly, subset analyses of the ABCSG-12 trial showed greater benefits from zoledronic acid in patients over 40 years of age who theoretically would have achieved more complete ovarian suppression. Together, these data support a potential role for zoledronic acid beyond bone health in breast cancer and suggest that the endocrine environment may influence the anticancer potential of zoledronic acid.

Bisphosphonates: prevention of bone metastases in breast cancer

Disease recurrence and distant metastases remain challenging for patients with breast cancer despite advances in early diagnosis, surgical expertise, and adjuvant therapy. Bone is the most common site for breast cancer metastasis, and the bone microenvironment plays a crucial role in harboring disseminated tumor cells (DTCs), a putative source of late relapse in and outside bone. Therefore, agents that affect bone metabolism might not only prevent the development of bone lesions but also provide meaningful reductions in the risk of relapse both in bone and beyond. Bisphosphonates bind to mineralized bone surfaces and are ingested by osteoclasts, wherein they inhibit osteolysis, thereby preventing the release of growth factors from the bone matrix. Therefore, the bone microenvironment becomes less conducive to survival and growth of DTCs and bone lesion formation. Recent trials of zoledronic acid in the adjuvant setting in breast cancer have demonstrated reduced disease recurrence in bone and other sites in premenopausal and postmenopausal women with early breast cancer. Based on the proven effect of bone protection during adjuvant endocrine therapy, new treatment guidelines recommend the routine use of bisphosphonates to prevent bone loss during adjuvant therapy, which may likely become the standard practice.

Low concentration amino-bisphosphonates stimulate human keratinocyte proliferation and in vitro wound healing

Amino-bisphosphonates (N-BPs) are widely used to treat a great variety of clinical conditions involving altered calcium metabolism, as well as to prevent bone metastases. The use of N-BPs, however, display well-known side effects, including cellular toxicity, mainly at soft tissue and mucosal level, that arise from N-BPs ability to induce cell apoptosis when administered at clinically relevant concentrations. The aim of this study was to evaluate, in an in vitro wound healing model, the effect of N-BPs low concentration (10 nM-10 µM) stimulation on keratinocyte cellular behaviour. Human keratinocytes were treated with neridronate and zoledronate, two N-BPs with different chemical structure and clinical potency, but sharing a common pharmacological target: farnesyl pyrophosphate (FPP) synthase. Surprisingly, at the tested concentrations, both drugs stimulated keratinocytes proliferation, upregulating cytokeratin 5 while downregulating filaggrin expression, and wound healing ability, without any significant effect on matrix metalloproteinase (MMP)-9 activity. The lack of N-BPs effect on MMP-9 activity indicates that wound closure, in our experimental model, is mainly due to an increase in cell proliferation rather than to an increase in cell migration. Therefore, it can be hypothesised that the observed wound healing results could be ascribed to an N-BPs mediated reduction of FPP endogenous levels, thus suggesting new possible clinical applications for these compounds.

Zoledronic acid in breast cancer: latest findings and interpretations

The intravenous nitrogen-containing bisphosphonate zoledronic acid has been shown to block multiple steps in tumor metastasis (e.g. angiogenesis, invasion, adhesion, proliferation) in preclinical and translational studies. Moreover, clinical data from the ABCSG-12 and ZO-FAST trials demonstrate significantly improved disease-free survival with zoledronic acid in the adjuvant breast cancer setting. In contrast to these two trials, recent interim results from the AZURE trial do not show a benefit from adding zoledronic acid to adjuvant therapy in the overall patient population. However, subset analyses of AZURE data show that zoledronic acid significantly improved overall survival in women who were more than 5 years postmenopausal or older than 60 years at baseline. Similarly, subset analyses of the ABCSG-12 trial data demonstrate greater benefits from zoledronic acid treatment in patients who theoretically would have achieved more complete ovarian suppression. These observations, together with the AZURE postmenopausal data, suggest that the endocrine environment may affect the potential anticancer activity of zoledronic acid. Indeed, current data support the possibility that zoledronic acid might be most effective for improving disease-free survival in the adjuvant breast cancer setting in women who are postmenopausal or have endocrine therapy-induced menopause.