Influence of zoledronic acid on disseminated tumor cells in bone marrow and survival: results of a prospective clinical trial

Bone-modifying agents for reducing bone loss in women with early and locally advanced breast cancer: a network meta-analysis

BACKGROUND

Bisphosphonates and receptor activator of nuclear factor-kappa B ligand (RANKL)-inhibitors are amongst the bone-modifying agents used as supportive treatment in women with breast cancer who do not have bone metastases. These agents aim to reduce bone loss and the risk of fractures. Bisphosphonates have demonstrated survival benefits, particularly in postmenopausal women.

OBJECTIVES

To assess and compare the effects of different bone-modifying agents as supportive treatment to reduce bone mineral density loss and osteoporotic fractures in women with breast cancer without bone metastases and generate a ranking of treatment options using network meta-analyses (NMAs).

SEARCH METHODS

We identified studies by electronically searching CENTRAL, MEDLINE and Embase until January 2023. We searched various trial registries and screened abstracts of conference proceedings and reference lists of identified trials.

SELECTION CRITERIA

We included randomised controlled trials comparing different bisphosphonates and RANKL-inihibitors with each other or against no further treatment or placebo for women with breast cancer without bone metastases.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias of included studies and certainty of evidence using GRADE. Outcomes were bone mineral density, quality of life, overall fractures, overall survival and adverse events. We conducted NMAs and generated treatment rankings.

MAIN RESULTS

Forty-seven trials (35,163 participants) fulfilled our inclusion criteria; 34 trials (33,793 participants) could be considered in the NMA (8 different treatment options). Bone mineral density We estimated that the bone mineral density of participants with no treatment/placebo measured as total T-score was -1.34. Evidence from the NMA (9 trials; 1166 participants) suggests that treatment with ibandronate (T-score -0.77; MD 0.57, 95% CI -0.05 to 1.19) may slightly increase bone mineral density (low certainty) and treatment with zoledronic acid (T-score -0.45; MD 0.89, 95% CI 0.62 to 1.16) probably slightly increases bone mineral density compared to no treatment/placebo (moderate certainty). Risedronate (T-score -1.08; MD 0.26, 95% CI -0.32 to 0.84) may result in little to no difference compared to no treatment/placebo (low certainty). We are uncertain whether alendronate (T-score 2.36; MD 3.70, 95% CI -2.01 to 9.41) increases bone mineral density compared to no treatment/placebo (very low certainty). Quality of life No quantitative analyses could be performed for quality of life, as only three studies reported this outcome. All three studies showed only minimal differences between the respective interventions examined. Overall fracture rate We estimated that 70 of 1000 participants with no treatment/placebo had fractures. Evidence from the NMA (16 trials; 19,492 participants) indicates that treatment with clodronate or ibandronate (42 of 1000; RR 0.60, 95% CI 0.39 to 0.92; 40 of 1000; RR 0.57, 95% CI 0.38 to 0.86, respectively) decreases the number of fractures compared to no treatment/placebo (high certainty). Denosumab or zoledronic acid (51 of 1000; RR 0.73, 95% CI 0.52 to 1.01; 55 of 1000; RR 0.79, 95% CI 0.56 to 1.11, respectively) probably slightly decreases the number of fractures; and risedronate (39 of 1000; RR 0.56, 95% CI 0.15 to 2.16) probably decreases the number of fractures compared to no treatment/placebo (moderate certainty). Pamidronate (106 of 1000; RR 1.52, 95% CI 0.75 to 3.06) probably increases the number of fractures compared to no treatment/placebo (moderate certainty). Overall survival We estimated that 920 of 1000 participants with no treatment/placebo survived overall. Evidence from the NMA (17 trials; 30,991 participants) suggests that clodronate (924 of 1000; HR 0.95, 95% CI 0.77 to 1.17), denosumab (927 of 1000; HR 0.91, 95% CI 0.69 to 1.21), ibandronate (915 of 1000; HR 1.06, 95% CI 0.83 to 1.34) and zoledronic acid (925 of 1000; HR 0.93, 95% CI 0.76 to 1.14) may result in little to no difference regarding overall survival compared to no treatment/placebo (low certainty). Additionally, we are uncertain whether pamidronate (905 of 1000; HR 1.20, 95% CI 0.81 to 1.78) decreases overall survival compared to no treatment/placebo (very low certainty). Osteonecrosis of the jaw We estimated that 1 of 1000 participants with no treatment/placebo developed osteonecrosis of the jaw. Evidence from the NMA (12 trials; 23,527 participants) suggests that denosumab (25 of 1000; RR 24.70, 95% CI 9.56 to 63.83), ibandronate (6 of 1000; RR 5.77, 95% CI 2.04 to 16.35) and zoledronic acid (9 of 1000; RR 9.41, 95% CI 3.54 to 24.99) probably increases the occurrence of osteonecrosis of the jaw compared to no treatment/placebo (moderate certainty). Additionally, clodronate (3 of 1000; RR 2.65, 95% CI 0.83 to 8.50) may increase the occurrence of osteonecrosis of the jaw compared to no treatment/placebo (low certainty). Renal impairment We estimated that 14 of 1000 participants with no treatment/placebo developed renal impairment. Evidence from the NMA (12 trials; 22,469 participants) suggests that ibandronate (28 of 1000; RR 1.98, 95% CI 1.01 to 3.88) probably increases the occurrence of renal impairment compared to no treatment/placebo (moderate certainty). Zoledronic acid (21 of 1000; RR 1.49, 95% CI 0.87 to 2.58) probably increases the occurrence of renal impairment while clodronate (12 of 1000; RR 0.88, 95% CI 0.55 to 1.39) and denosumab (11 of 1000; RR 0.80, 95% CI 0.54 to 1.19) probably results in little to no difference regarding the occurrence of renal impairment compared to no treatment/placebo (moderate certainty).

AUTHORS' CONCLUSIONS

When considering bone-modifying agents for managing bone loss in women with early or locally advanced breast cancer, one has to balance between efficacy and safety. Our findings suggest that bisphosphonates (excluding alendronate and pamidronate) or denosumab compared to no treatment or placebo likely results in increased bone mineral density and reduced fracture rates. Our survival analysis that included pre and postmenopausal women showed little to no difference regarding overall survival. These treatments may lead to more adverse events. Therefore, forming an overall judgement of the best ranked bone-modifying agent is challenging. More head-to-head comparisons, especially comparing denosumab with any bisphosphonate, are needed to address gaps and validate the findings of this review.

How much do we know about the metastatic process?

Cancer cells can leave their primary sites and travel through the circulation to distant sites, where they lodge as disseminated cancer cells (DCCs), even during the early and asymptomatic stages of tumor progression. In experimental models and clinical samples, DCCs can be detected in a non-proliferative state, defined as cellular dormancy. This state can persist for extended periods until DCCs reawaken, usually in response to niche-derived reactivation signals. Therefore, their clinical detection in sites like lymph nodes and bone marrow is linked to poor survival. Current cancer therapy designs are based on the biology of the primary tumor and do not target the biology of the dormant DCC population and thus fail to eradicate the initial or subsequent waves of metastasis. In this brief review, we discuss the current methods for detecting DCCs and highlight new strategies that aim to target DCCs that constitute minimal residual disease to reduce or prevent metastasis formation. Furthermore, we present current evidence on the relevance of DCCs derived from early stages of tumor progression in metastatic disease and describe the animal models available for their study. We also discuss our current understanding of the dissemination mechanisms utilized by genetically less- and more-advanced cancer cells, which include the functional analysis of intermediate or hybrid states of epithelial-mesenchymal transition (EMT). Finally, we raise some intriguing questions regarding the clinical impact of studying the crosstalk between evolutionary waves of DCCs and the initiation of metastatic disease.

Biomarkers of minimal residual disease and treatment

Minimal residual disease (MRD) has been defined as a very small numbers of cancer cells that remain in the body after curative treatment. Its presence or absence will ultimately determine prognosis. With the introduction of new technologies the presence of MRD in patients with solid tumours can be detected and characterized. As MRD predicts future relapse, be it early or late treatment failure, in an otherwise asymptomatic patient its treatment and when to start treatment remains to be determined. Thus the concepts of personalized medicine using different biomarkers to classify the biological properties of MRD maybe come possible. Based on this determinations it may be possible to use targeted therapies rather than all patients with the same type of cancer receiving a standard treatment. However, it is important to understand the limitations of the different technologies, what these techniques are detecting and how they may help in the treatment of patients with cancer. The majority of published studies are in patients with metastatic cancer and there are few reports in patients with MRD. In this chapter the concept of MRD, the methods used to detect it and what treatments may be effective based on the biological characteristics of the tumour cells as determined by different biomarkers is reviewed. MRD depends on the phenotypic properties of the tumour cells to survive in their new environment and the anti-tumour immune response. This is a dynamic process and changes with time in the wake of immunosuppression caused by the tumour cells and/or the effects of treatment to select resistant tumour cells. With the use of biomarkers to typify the characteristics of MRD and the development of new drugs a personalized treatment can be designed rather than all patients given the same treatment. Patients who are initially negative for MRD may not require further treatment with liquid biopsies used to monitor the patients during follow-up in order to detect those patients who may become MRD positive. The liquid biopsy used during the follow up of MRD positive patients can be used to detect changes in the biological properties of the tumour cells and thus may need treatment changes to overcome tumour cell resistance.

Targeting cancer cell dormancy

The field of tumour dormancy, originally defined as a clinical phenomenon of late recurrence after a long, apparently disease-free period, has seen significant advances that now allow us to think about monitoring and targeting dormant tumour cells to prevent relapse. In this Viewpoint article, we asked experts to share their views on the steps that are needed to translate dormancy research into the clinic.

Dormancy in Breast Cancer

The pattern of delayed recurrence in a subset of breast cancer patients has long been explained by a model that incorporates a variable period of cellular or tumor mass dormancy prior to disease relapse. In this review, we critically evaluate existing data to develop a framework for inferring the existence of dormancy in clinical contexts of breast cancer. We integrate these clinical data with rapidly evolving mechanistic insights into breast cancer dormancy derived from a broad array of genetically engineered mouse models as well as experimental models of metastasis. Finally, we propose actionable interventions and discuss ongoing clinical trials that translate the wealth of knowledge gained in the laboratory to the long-term clinical management of patients at a high risk of developing recurrence.

Bone serves as a transfer station for secondary dissemination of breast cancer

Metastasis is responsible for the majority of deaths among breast cancer patients. Although parallel polyclonal seeding has been shown to contribute to organ-specific metastasis, in the past decade, horizontal cross-metastatic seeding (metastasis-to-metastasis spreading) has also been demonstrated as a pattern of distant metastasis to multiple sites. Bone, as the most frequent first destination of breast cancer metastasis, has been demonstrated to facilitate the secondary dissemination of breast cancer cells. In this review, we summarize the clinical and experimental evidence that bone is a transfer station for the secondary dissemination of breast cancer. We also discuss the regulatory mechanisms of the bone microenvironment in secondary seeding of breast cancer, focusing on stemness regulation, quiescence-proliferation equilibrium regulation, epigenetic reprogramming and immune escape of cancer cells. Furthermore, we highlight future research perspectives and strategies for preventing secondary dissemination from bone.

Bisphosphonates and Prevention of the Perimenopausal Breast Cancer Recurrence: A Systematic Review and Meta-Analysis

PURPOSE

Bisphosphonates (BPs) have a powerful effect on reducing bone resorption and improving the survival of patients with breast cancer. We aimed to investigate the impact of BP treatment on the prevention of recurrence, metastasis, and death of breast cancer survivors in the perimenopausal period.

METHODS

The search strategy aimed to identify both published and unpublished studies in PubMed, Web of Science, Scopus, Embase, ProQuest, and Google Scholar in March 2021. Two independent reviewers assessed quantitative papers selected for retrieval for methodological validity before being included in the review using standardized critical appraisal instruments from the Joanna Briggs Institute (JBI) Meta-Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI). Statistical meta-analysis was performed using Review Manager (RevMan) 5.4 statistical software when the data were homogenous. Meta-analysis was performed by calculating the effect size (hazard ratio; HR) and 95% confidence intervals (CIs).

RESULTS

Twenty-one studies were eligible for this systematic review and meta-analysis. The overall The HRs for disease-free survival (DFS) and overall survival (OS) in women who received BPs were 0.89 (95% CI, 0.83-0.97; p = 0.005), and 0.75 (95% CI, 0.63-0.89; p = 0.001), respectively. The results showed that BPs had a significant effect on the prevention of locoregional (HR, 0.64; 95% CI, 0.42-0.97; p = 0.04), bone (95% CI, 0.74-0.95; p ≤ 0.001), and distant metastases (HR, 0.77; 95% CI, 0.62-0.94; p = 0.01). In the subgroup analysis based on study design, the only insignificant HR in the included randomized controlled trials (RCTs) was that of locoregional metastasis.

CONCLUSION

Although BPs have a promising effect on DFS, OS, and bone metastasis of perimenopausal women survivors of breast cancer, more RCTs are needed to evaluate their effect on other survivors' outcomes.

Does the Presence of Circulating Tumor Cells in High-Risk Early Breast Cancer Patients Predict the Site of First Metastasis—Results from the Adjuvant SUCCESS A Trial

Simple Summary

Due to recent advances in breast cancer detection and treatment strategies, the number of breast cancer survivors has increased over the past decades. However, breast cancer follow-up guidelines have not changed for years. The presence of CTCs detected during follow-up has been shown to indicate poor prognosis in high-risk breast cancer patients. Here, we evaluated if the presence of CTCs also indicates the site of metastatic disease by analyzing CTC status and metastatic location in 206 patients with distant recurrence from the large adjuvant breast cancer trial SUCCESS A. Patients who were CTC-positive both before and after chemotherapy were more likely to show bone-only first distant disease (37.5% vs. 21.0%) and first distant disease at multiple sites (31.3% vs. 12.6%) than patients without CTCs. These data indicate that CTCs might serve as a liquid biopsy surveillance-marker enabling risk-stratification for deciding on further adjuvant add-on-treatment.

Abstract

The prognostic relevance of circulating tumor cells (CTCs) in breast cancer is well established. However, little is known about the association of CTCs and site of first metastasis. In the SUCCESS A trial, 373 out of 3754 randomized high-risk breast cancer patients developed metastatic disease. CTC status was assessed by the FDA-approved CellSearch^®-System (Menarini Silicon Biosystems, Bologna, Italy) in 206 of these patients before chemotherapy and additionally in 159 patients after chemotherapy. CTCs were detected in 70 (34.0%) of 206 patients before (median 2 CTCs, 1–827) and in 44 (27.7%) of 159 patients after chemotherapy (median 1 CTC, 1–124); 16 (10.1%) of 159 patients were CTC-positive at both timepoints. The site of first distant disease was bone-only, visceral-only, and other-site-only in 44 (21.4%), 60 (29.1%), and 74 (35.9%) patients, respectively, while 28 (13.6%) patients had multiple sites of first metastatic disease. Patients with CTCs at both timepoints more often showed bone-only first distant disease (37.5% vs. 21.0%) and first distant disease at multiple sites (31.3% vs. 12.6%) than patients without CTCs before and/or after chemotherapy (p = 0.027). In conclusion, the presence of CTCs before and after chemotherapy is associated with multiple-site or bone-only first-distant disease and may trigger intensified follow-up and perhaps further treatment.

Clinical and Biological Aspects of Disseminated Tumor Cells and Dormancy in Breast Cancer

Progress in detection and treatment have drastically improved survival for early breast cancer patients. However, distant recurrence causes high mortality and is typically considered incurable. Cancer dissemination occurs via circulating tumor cells (CTCs) and up to 75% of breast cancer patients could harbor micrometastatses at time of diagnosis, while metastatic recurrence often occurs years to decades after treatment. During clinical latency, disseminated tumor cells (DTCs) can enter a state of cell cycle arrest or dormancy at distant sites, and are likely shielded from immune detection and treatment. While this is a challenge, it can also be seen as an outstanding opportunity to target dormant DTCs on time, before their transformation into lethal macrometastatic lesions. Here, we review and discuss progress made in our understanding of DTC and dormancy biology in breast cancer. Strides in our mechanistic insights of these features has led to the identification of possible targeting strategies, yet, their integration into clinical trial design is still uncertain. Incorporating minimally invasive liquid biopsies and rationally designed adjuvant therapies, targeting both proliferating and dormant tumor cells, may help to address current challenges and improve precision cancer care.

Fracture Risk Evaluation of Bone Metastases: A Burning Issue

Major progress has been achieved to treat cancer patients and survival has improved considerably, even for stage-IV bone metastatic patients. Locomotive health has become a crucial issue for patient autonomy and quality of life. The centerpiece of the reflection lies in the fracture risk evaluation of bone metastasis to guide physician decision regarding physical activity, antiresorptive agent prescription, and local intervention by radiotherapy, surgery, and interventional radiology. A key mandatory step, since bone metastases may be asymptomatic and disseminated throughout the skeleton, is to identify the bone metastasis location by cartography, especially within weight-bearing bones. For every location, the fracture risk evaluation relies on qualitative approaches using imagery and scores such as Mirels and spinal instability neoplastic score (SINS). This approach, however, has important limitations and there is a need to develop new tools for bone metastatic and myeloma fracture risk evaluation. Personalized numerical simulation qCT-based imaging constitutes one of these emerging tools to assess bone tumoral strength and estimate the femoral and vertebral fracture risk. The next generation of numerical simulation and artificial intelligence will take into account multiple loadings to integrate movement and obtain conditions even closer to real-life, in order to guide patient rehabilitation and activity within a personalized-medicine approach.

Evaluation of disseminated tumor cells and circulating tumor cells in patients with breast cancer receiving adjuvant zoledronic acid

We evaluated disseminated tumor cells (DTCs) and circulating tumor cells (CTCs) in patients with stage I-III breast cancer with >4 MM/mL DTC at baseline who received adjuvant zoledronic acid (ZOL). ZOL was administered every 4 weeks for 24 months, and patients underwent bone marrow aspiration at baseline, and 12 and 24 months of ZOL. Complete DTC response (<4 DTC/mL), serial CTCs, survival, recurrence, and toxicity were determined. Forty-five patients received ZOL. Median baseline DTC was 13.3/mL. Significant reduction in median DTC occurred from baseline to 12 months, and 24 months. Complete DTC response was seen in 32% at 12 months, and 26% at 24 months. Nine patients developed recurrence. Baseline DTC > 30/mL and CTC > 0.8/mL were significantly associated with recurrence and death. Serial reduction in DTCs occurred. Higher baseline DTC > 30/mL and CTC > 0.8/mL correlated with recurrence and death.

Bisphosphonates and breast cancer survival: a meta-analysis and trial sequential analysis of 81508 participants from 23 prospective epidemiological studies

BACKGROUND

We assessed the effect of bisphosphonates (BPs) on breast cancer (BCa) patient survival and explored how long the effect can persist after treatment.

METHODS

We performed a meta-analysis and trial sequential analysis (TSA) of prospective studies including randomized controlled trials (RCTs) and cohort studies. We performed extensive sensitivity analyses to assess the robustness of the findings.

RESULTS

Seventeen RCTs and eight cohorts with 81508 BCa patients were identified. A significant beneficial effect of BPs on BCa survival was found (RR, 0.725; 95% CI, 0.627-0.839), and the TSA results also suggested firm evidence for this beneficial effect. Both summarized results from RCTs and cohorts provided firm evidence for this effect, although the effect estimates were stronger from cohorts than RCTs (RR, 0.892; 95% CI, 0.829-0.961; 0.570; 95% CI, 0.436-0.745; respectively). This beneficial effect was confirmed for bone-metastases (RR, 0.713; 95% CI, 0.602-0.843) and postmenopausal women (RR, 0.737; 95% CI, 0.640-0.850). Importantly, our results demonstrated that this beneficial effect was retained at least 1-2 years after treatment completion (RR, 0.780; 95% CI, 0.638-0.954) and could persist for up to more than 4 years after treatment completion (RR, 0.906; 95% CI, 0.832-0.987). Extensive sensitivity analyses showed the robustness of our results. The GRADE quality of evidence was generally judged to be moderate to high.

CONCLUSIONS

The present study provides firm evidence for a significant beneficial effect of BPs on BCa survival in patients with early-stage BCa, and this effect was retained at least 1-2 years after BP treatment completion.

Bone-modifying Agents (BMAs) in Breast Cancer

Bone-modifying agents (BMAs) are mainstays in breast cancer and prevent and treat osteoporosis in early-stage disease and reduce skeletal metastases complications in advanced disease. There is some evidence to support that BMA also prevents skeletal metastases and improves overall survival. Bone loss occurs with chemotherapy-induced ovarian failure, gonadotrophin-releasing hormone (GnRH) agonists, and aromatase inhibitors. In some women, the bone loss will be of sufficient magnitude to increase the risks of osteoporosis or fractures. Recommended steps in osteoporosis prevention or treatment include risk factor assessment, taking adequate amounts of calcium and vitamin D3, and periodic evaluations with dual-energy x-ray absorptiometry scanning. If clinically indicated by the T-scores and fracture-risk prediction algorithms treat with oral, IV bisphosphonates or subcutaneous denosumab (DEN). Zoledronic acid (ZA) or DEN reduces skeletal metastases complications, including pathological fracture, spinal cord compression, or the necessity for radiation or surgery to bone. Also, both of these drugs have the side-effect of osteonecrosis at a similar incidence. Monthly administration of ZA or DEN is standard, but several recent randomized trials show noninferiority between ZA monthly and every 3-month ZA. Every 3-month ZA is a new standard of care. Similar trials of the schedule of DEN are ongoing. ZA anticancer effect is only in postmenopausal women or premenopausal women rendered postmenopausal by GnRH agonists or bilateral oopherectomy. High-risk women, either postmenopausal or premenopausal, receiving GnRH/oopherctomy should consider adjuvant ZA. There are insufficient data to support DEN in this setting. Herein, this narrative review covers the mechanism of action of BMA, randomized clinical trials, and adverse events, both common and rare.

Long-term outcome of (neo)adjuvant zoledronic acid therapy in locally advanced breast cancer

PURPOSE

The role of zoledronic acid (ZOL), a bone-targeted bisphosphonate, in the treatment of patients with breast cancer remains an active area of study. Here, we report the long-term outcomes of a randomized placebo-controlled phase II clinical trial in which ZOL treatment was added to neoadjuvant chemotherapy in women with locally advanced breast cancer.

METHODS

120 women with clinical stage II-III (≥ T2 and/or ≥ N1) newly diagnosed breast cancer were randomized to receive either 4 mg intravenous ZOL every 3 weeks for 1 year (17 total doses) beginning with the first dose of neoadjuvant chemotherapy, or chemotherapy alone. Clinical endpoints included time to recurrence (TTR), time to bone recurrence (TTBR), time to non-bone recurrence (TTNBR), breast cancer survival (BCS) and overall survival (OS).

RESULTS

With a median follow-up interval of 14.4 years, there were no significant differences in any of the clinical endpoints studied between the control and ZOL groups in the overall study population. However, ER+/HER2- patients younger than age 45 who were treated with ZOL had significantly worse TTR and TTNBR with a trend towards worse TTBR, BCS and OS (TTR: P = 0.024, HR 6.05 [1.26-29.1]; TTNBR: P = 0.026, HR 6.94 [1.26-38.1]; TTBR: P = 0.054, HR 6.01 [0.97-37.1]; BCS: P = 0.138, HR 4.43 [0.62-31.7]; OS: P = 0.138, HR 4.43 [0.62-31.7]). These differences were not seen in older ER+/HER2- patients or triple-negative patients of any age.

CONCLUSION

Addition of ZOL to neoadjuvant therapy did not significantly affect clinical outcomes in the overall study population but was associated with increased extra-skeletal recurrence and a trend towards worse survival in ER+/HER2- patients younger than age 45. These findings suggest caution when using zoledronic acid in young, premenopausal women with locally advanced breast cancer and warrant further investigation. Clinical Trial Registration Number NCT00242203, Date of Registration: 10/17/2005.

Oestradiol Contributes to Differential Antitumour Effects of Adjuvant Zoledronic Acid Observed Between Pre- and Post-Menopausal Women

Clinical trials have demonstrated that adding zoledronic acid (Zol) to (neo)adjuvant standard of care has differential antitumour effects in pre- and post-menopausal women: Both benefit from reduced recurrence in bone; however, while postmenopausal women also incur survival benefit, none is seen in premenopausal women treated with adjuvant bisphosphonates. In the current study, we have used mouse models to investigate the role of oestradiol in modulating potential antitumour effects of Zol. Pre-, peri-, and post-menopausal concentrations of oestradiol were modelled in BALB/c wild-type, BALB/c nude, and C57BL/6 mice by ovariectomy followed by supplementation with oestradiol. Mice also received 40 mg/kg/day goserelin to prevent ovariectomy-induced increases in follicle-stimulating hormone (FSH). Metastasis was modelled following injection of MDA-MB-231, 4T1, or E0771 cells after ovariectomy and saline or 100 μg/kg Zol administered weekly. Supplementing ovariectomised mice with 12.5 mg/ml, 1.38 mg/ml, and 0 ng/ml oestradiol, in the presence of goserelin, resulted in serum concentrations of 153.16 ± 18.10 pg/ml, 48.64 ± 18.44 pg/ml, and 1.00 ± 0.27 pg/ml oestradiol, which are equivalent to concentrations found in pre-, peri-, and post-menopausal humans. Osteoclast activity was increased 1.5-1.8-fold with peri- and post-menopausal compared with premenopausal oestradiol, resulting in a 1.34-1.69-fold reduction in trabecular bone. Zol increased trabecular bone in all groups but did not restore bone to volumes observed under premenopausal conditions. In tumour-bearing mice, Zol reduced bone metastases in BALB/c (wild-type and nude), with greatest effects seen under pre- and post-menopausal concentrations of oestradiol. Zol did not affect soft tissue metastases in immunocompetent BALB/c mice but increased metastases 3.95-fold in C57BL/6 mice under premenopausal concentrations of oestradiol. In contrast, Zol significantly reduced soft tissue metastases 2.07 and 4.69-fold in immunocompetent BALB/c and C57BL/6 mice under postmenopausal oestradiol, mirroring the results of the clinical trials of (neo)adjuvant bisphosphonates. No effects on soft tissue metastases were observed in immunocompromised mice, and differences in antitumour response did not correlate with musculoaponeurotic fibrosarcoma (MAF), macrophage capping protein (CAPG), or PDZ domain containing protein GIPC1 (GIPC1) expression. In conclusion, oestradiol contributes to altered antitumour effects of Zol observed between pre- and post-menopausal women. However, other immunological/microenvironmental factors are also likely to contribute to this phenomenon.

Oestrogen and zoledronic acid driven changes to the bone and immune environments: Potential mechanisms underlying the differential anti-tumour effects of zoledronic acid in pre- and post-menopausal conditions

Late stage breast cancer commonly metastasises to bone and patient survival averages 2-3 years following diagnosis of bone involvement. One of the most successful treatments for bone metastases is the bisphosphonate, zoledronic acid (ZOL). ZOL has been used in the advanced setting for many years where it has been shown to reduce skeletal complications associated with bone metastasis. More recently, several large adjuvant clinical trials have demonstrated that administration of ZOL can prevent recurrence and improve survival when given in early breast cancer. However, these promising effects were only observed in post-menopausal women with confirmed low concentrations of circulating ovarian hormones. In this review we focus on potential interactions between the ovarian hormone, oestrogen, and ZOL to establish credible hypotheses that could explain why anti-tumour effects are specific to post-menopausal women. Specifically, we discuss the molecular and immune cell driven mechanisms by which ZOL and oestrogen affect the tumour microenvironment to inhibit/induce tumour growth and how oestrogen can interact with zoledronic acid to inhibit its anti-tumour actions.

Osteoporosis: A Long-Term and Late-Effect of Breast Cancer Treatments

Simple Summary

Osteoporosis is a prevalent condition affecting 200 million individuals world-wide. Estimates are about one in three women will experience a fragility fracture of hip, spine or wrist. Common breast cancer treatments, such as aromatase inhibitors in postmenopausal women and chemotherapy-induced ovarian failure in premenopausal women, cause bone loss that in some women will lead to osteoporosis and fragility fractures. Fragility fractures cause morbidity and mortality and are entirely preventable. Prevention or treatment of osteoporosis includes lifestyle modifications (e.g., reducing smoking and excessive alcohol consumption, and increasing physical activity), taking calcium and vitamin D3, screening for osteoporosis with dual-energy absorptiometry, and treatment, if clinically indicated, with ether oral bisphosphonates, intravenous zoledronic acid, or subcutaneous denosumab. This chapter reviews the pathogenesis of osteoporosis, the magnitude of bone loss related to common breast cancer treatments, osteoporosis risk factor assessment and screening, and the specific drugs to treat or prevent osteoporosis.

Abstract

Osteoporosis is both a long-term effect (occurs during treatment and extends after treatment) and a late-effect (occurs after treatment ends) of breast cancer treatments. The worldwide prevalence of osteoporosis is estimated to be some 200 million patients. About one in three postmenopausal women will experience an osteoporotic (or fragility) fracture of the hip, spine, or wrist. breast cancer treatments, including gonadotropin-releasing hormone (GnRH) agonists, chemotherapy-induced ovarian failure (CIOF), and aromatase inhibitors (AIs), cause bone loss and increase the risks of osteoporosis. Also, breast cancer is a disease of aging, and most of the “one in eight” lifetime risks of breast cancer are in women in their sixth, seventh, and eighth decades. The majority of women diagnosed with breast cancers today will be long-term survivors and experience personal cures. It is the coalescence of osteoporosis with breast cancer, two common and age-related conditions that make osteoporosis relevant in women with breast cancer throughout the continuum from diagnosis, treatment, and survivorship. It is critical to remember that women (and men) will lose bone after age thirty years. However, only certain women will lose bone of sufficient magnitude to merit treatment with anti-osteoporosis drugs. The narrative review is intended for medical, surgical, radiation oncologists, and other mid-level providers, and provides an overview of bone loss and the prevention and treatment of osteoporosis.

Benefits of Bisphosphonate Therapy: Beyond the Skeleton

PURPOSE OF REVIEW

Recent evidence from clinical trials and observational studies raises the possibility that bisphosphonate use might confer a lower risk of cardiovascular disease and cancer, resulting in a mortality benefit. This review summarizes clinical and preclinical studies examining the non-skeletal effects of bisphosphonates.

RECENT FINDINGS

Data from clinical trials are conflicting regarding whether or not bisphosphonates have beneficial effects on mortality, cardiovascular events, or cancer incidence. No clinical trials have assessed these outcomes as primary endpoints, and most trials were shorter than 4 years. Observational data suggest that bisphosphonate users may have lower mortality, delayed progression of vascular calcification and atherosclerotic burden, and reduced incidence of breast and colorectal cancer compared to non-users. Preclinical studies confirm that bisphosphonates can be taken up by macrophages and monocytes, and nitrogen-containing bisphosphonates have the ability to disrupt the mevalonate pathway within these cells. In this manner, bisphosphonates exert anti-atherogenic and anti-cancer effects. Bisphosphonates also appear to exert protective effects on vascular smooth muscle cells and endothelial cells and may have direct cytotoxic effects on cancer cells. The balance of evidence does not support bisphosphonate treatment for the primary purpose of improving non-skeletal outcomes, although appropriately designed controlled trials that further explore this possibility are both justified and required. Patients with skeletal indications for bisphosphonate therapy can be reassured that these agents are not associated with increased mortality, cardiovascular disease, or cancer incidence.

Extra-skeletal effects of bisphosphonates

Bisphosphonates (BPs) are pyrophosphate analogues widely used in diseases related to bone loss and increased bone turnover. Their high affinity for bone hydroxyapatite makes them ideal agents for bone diseases, while preventing them from reaching other cells and tissues. Data of the last decade, however, have demonstrated extra-skeletal tissue deposition and a variety of non-skeletal effects have been recently recognized. As such, BPs have been shown to exert anti-tumor, immunomodulatory, anti-inflammatory and anti-diabetic effects. In addition, new delivery systems (liposomes, nanoparticles, hydrogels) are being developed in an effort to expand BPs clinical application to extra-skeletal tissues and enhance their overall therapeutic spectrum and effectiveness. In the present review, we outline current data on extra-skeletal actions of bisphosphonates and attempt to unravel the underlying pathophysiological mechanisms.

Disseminated Tumor Cells and Dormancy in Breast Cancer Progression

Hematogenous dissemination of single cancer cells is a common phenomenon in patients with solid tumors. These cells may experience different fates: most will die during the process; some will grow into metastasis and some will persist in secondary homing sites for many years in a state referred to as dormancy. The mechanisms of this state are still not clear; single cancer cells can survive either by completely withdrawing from the cell cycle or by continuing to proliferate at a slow rate that is counterbalanced by cell death. Another hypothesis assumes that at least some of dormant tumor cells feature stem cell-like characteristics that may contribute to their extremely long half-lives and enhance chemotherapy resistance. Breast cancer is particularly known for prolonged periods of clinical freedom of disease (sometimes up to 20-30 years), followed by a distant relapse. In this chapter, we explore the relationship between the clinical phenomenon of tumor dormancy and the disseminated tumor cells and discuss the potential implications for treatment.

Circulating and Disseminated Tumor Cells in Breast Carcinoma: Report from the Consensus Conference on Tumor Cell Dissemination during the 39th Annual Meeting of the German Society of Senology, Berlin, 27 June 2019

Hematogenous dissemination of single tumor cells from the primary tumor is a common phenomenon in most solid malignancies. In breast cancer, presence of circulating tumor cells (CTCs) in the peripheral blood and disseminated tumor cells (DTCs) in bone marrow predicts poor clinical outcome, both in early and metastatic setting. Beyond that, persistence of CTCs/DTCs is associated with shorter relapse-free interval as well. Numerous studies have shown that these cells differ from tumor cells in the primary tumor with regard to hormone and HER2 receptor status and it has been hypothesized that some of them might be in fact cancer stem cells. Recently, the first positive study on CTC-based therapy interventions has been presented at the San Antonio Breast Cancer Symposium 2018, demonstrating that detection of CTCs may guide treatment decisions in metastatic HR-positive HER2-negative disease. In this review, we present the current state of evidence of tumor cell dissemination and discuss the implications for future trials.

Dissimilar patterns of tumor-infiltrating immune cells at the invasive tumor front and tumor center are associated with response to neoadjuvant chemotherapy in primary breast cancer

BACKGROUND

Tumor-infiltrating lymphocytes (TILs) are described as an important immune modulator in the tumor microenvironment and are associated with breast cancer (BC) outcome. The spatial analysis of TILs and TIL subtype distribution at the invasive tumor front (ITF) and the tumor center (TC) might provide further insights into tumor progression.

METHODS

We analyzed core biopsies from 87 pre-therapeutic BC patients for total TILs and the following subtypes: CD3+, CD4+, CD8+, CD20+ and CD68+ cells in correlation to clinicopathological parameters and disseminated tumor cells (DTCs) in the bone marrow.

RESULTS

TILs and TIL subtypes showed significantly different spatial distribution among both tumor areas. TILs, especially CD3+ T cells were associated with the tumor status and tumor grading. BC patients responding to neoadjuvant chemotherapy had significantly more TILs and CD3+ T cells at the TC. The presence of DTCs after NACT was related to CD4+ infiltration at the TC.

CONCLUSION

The dissimilar spatial association of TILs and TIL subtypes with clinicopathological parameters, NACT response and minimal residual disease underlines the necessity of detailed TIL analysis for a better understanding of immune modulatory processes.

Circulating and Disseminated Tumour Cells in Breast Carcinoma: Report from the Consensus Conference on Tumour Cell Dissemination during the 38th Annual Meeting of the German Society of Senology, Berlin, 14 June 2018

Haematogenic dissemination of tumour cells in breast carcinoma is among the most intensively researched areas in translational oncology. Large meta-analyses have shown the prognostic relevance of the disseminated tumour cells in the bone marrow and circulating tumour cells in the peripheral blood in the adjuvant as well as metastatic setting. The current status of the research was discussed in detail during the annual meeting of the German Society of Senology in Berlin. The following conference report gives an overview of the clinical study landscape and the new methodological developments for improving the detection and phenotyping of the circulating and disseminated tumour cells.

Prognostic Value of RANKL/OPG Serum Levels and Disseminated Tumor Cells in Nonmetastatic Breast Cancer

PURPOSE

We assessed serum concentrations of the receptor activator of NFκB ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG), two proteins implicated in the development and progression of breast cancer, in 509 patients with primary, nonmetastatic breast cancer. Then the results were evaluated with regards to the occurrence of bone metastases, the presence of disseminated tumor cells (DTC) in the bone marrow, survival, and risk of developing metastatic disease.

EXPERIMENTAL DESIGN

Before surgery, two bone marrow aspirates were analyzed for DTC using density centrifugation followed by immunocytochemistry (pan-cytokeratin antibody A45-B/B3). RANKL and OPG levels in the serum were measured by ELISA.

RESULTS

RANKL levels were significantly lower in women >60 years (P < 0.0001) and RANKL/OPG ratios higher in lymph node-positive patients (P < 0.05). High OPG serum levels were associated with a higher risk of death from breast cancer [HR 1.94; 95% confidence interval (CI) 1.23-3.07; P = 0.005] and OPG was an independent prognostic marker for breast cancer-specific survival (BCSS; multivariate analyses, P = 0.035). RANKL levels were 33% higher (P < 0.0001) in DTC^pos patients (41%), whereas high levels were associated with a significantly better BCSS in DTC^neg patients as compared with low levels (HR 0.524; 95% CI 0.30-0.95; P = 0.04). RANKL serum levels were significantly increased in patients who developed bone metastases (P = 0.01) and patients within the highest quartile of RANKL had a significantly increased risk of developing bone metastases compared with those in the lowest (HR 4.62; 95% CI 1.49-14.34; P = 0.03).

CONCLUSIONS

These findings warrant further investigation as they provide a rationale for novel diagnostic or therapeutic approaches.

Interdisciplinary Screening, Diagnosis, Therapy and Follow-up of Breast Cancer. Guideline of the DGGG and the DKG (S3-Level, AWMF Registry Number 032/045OL, December 2017) - Part 2 with Recommendations for the Therapy of Primary, Recurrent and Advanced Breast Cancer

Purpose The aim of this official guideline coordinated and published by the German Society for Gynecology and Obstetrics (DGGG) and the German Cancer Society (DKG) was to optimize the screening, diagnosis, therapy and follow-up care of breast cancer. Method The process of updating the S3 guideline published in 2012 was based on the adaptation of identified source guidelines. They were combined with reviews of evidence compiled using PICO (Patients/Interventions/Control/Outcome) questions and with the results of a systematic search of literature databases followed by the selection and evaluation of the identified literature. The interdisciplinary working groups took the identified materials as their starting point and used them to develop suggestions for recommendations and statements, which were then modified and graded in a structured consensus process procedure. Recommendations Part 2 of this short version of the guideline presents recommendations for the therapy of primary, recurrent and metastatic breast cancer. Loco-regional therapies are de-escalated in the current guideline. In addition to reducing the safety margins for surgical procedures, the guideline also recommends reducing the radicality of axillary surgery. The choice and extent of systemic therapy depends on the respective tumor biology. New substances are becoming available, particularly to treat metastatic breast cancer.

Bone-Modifying Agents in Early-Stage and Advanced Breast Cancer

PURPOSE OF REVIEW

Bone-modifying agents have an important role in the treatment of patients with bone mineral density loss, early-stage breast cancer to reduce risk of recurrence, and metastatic breast cancer with bone involvement. Here we review mechanisms of action of these agents and clinical indications for their use.

RECENT FINDINGS

The meta-analysis undertaken by the Early Breast Cancer Trialists' Collaborative Group showed that the use of bisphosphonates was associated with a decreased risk of breast cancer recurrence.

SUMMARY

The effect of bisphosphonates and receptor activator of nuclear factor kappa-B ligand inhibitors on bone health provides an opportunity to decrease the incidence of skeletal-related events and improve cancer outcomes in certain subsets of patients.

Minimum Residual Disease in Patients Post Radical Prostatectomy for Prostate Cancer: Theoretical Considerations, Clinical Implications and Treatment Outcome

Introduction:

Minimal residual disease (MRD) remaining after curative therapy for prostate cancer has the potential for growth and can result in metastasis. Circulating prostate cells (CPCs) and bone marrow micro-metastasis (mM) could represent different types of MRD. We here determined; biochemical failure free survival rates; time to BF after 10 years follow-up; and the presence of CPCs and mM in patients treated with radical prostatectomy (RP) for prostate cancer.

Methods and Patients:

One month after RP, blood and bone marrow were sampled for assessment of CPCs and mM. Cases were classified as: group A, CPC negative and mM negative; group B, CPC negative and mM positive; Group C, CPC positive and mM negative; and Group D, CPC positive and mM positive. Subjects were followed with serial determination of PSA levels, recording the time at which BF occurred defined as a serum PSA >0.2ng/ml. After ten years of follow-up Kaplan-Meier survival curves were generated and the restricted mean survival time (RMST) for each group calculated.

Results:

A total of 321 men participated, 140 in group A with survival of 92.7% (86.3 to 96.2), 39 in group B with 55.8% (37.2 to 70.9); 54 in group C with 6.41% (1.19 to 18.21) and 88 in group D with 4.96%(1.64 to 11.13%. The RMST (in years) were: group A, 9.47 (9.24 to 9.69); group B, 9.23 (8.87 to 9.58); group C, 4.62 (4.46 to 4.77); and group D, 3.57 (3.52 and 3.63) (p-value<0.001 between groups: A versus C and D, B versus C and D).

Conclusions:

CPC positive men have more aggressive disease, with increased early failure; men who are only positive for mM are at greater risk of late failure. These two forms of MRD represent different clinical entities with respect to biochemical failure and could be used to guide clinical treatment decisions.

Reproductive hormone analyses and effects of adjuvant zoledronic acid in early breast cancer - An AZURE (BIG 01/04) sub-study

PURPOSE

Adjuvant bisphosphonates have been shown to improve disease outcomes in early breast cancer in women who are postmenopausal at the start of treatment. We explored the influence of pretreatment serum levels of reproductive hormones in the hypothalamic-pituitary-gonadal (HPG) axis from a subset of patients included in the AZURE trial to investigate their impact on disease recurrence and whether reproductive hormone measurements are of value in selecting patients for treatment with adjuvant zoledronic acid.Patients and methods; The AZURE trial is an academic, multi-centre, international phase III trial that randomised patients to standard adjuvant therapy (chemotherapy and/or endocrine therapy)±intravenous zoledronic acid, 4 mg for 5 years. Serum from 865 patients taken at randomisation was stored at -80 °C prior to central batch analysis for inhibin A, oestradiol and follicle stimulating hormone (FSH). We assessed the clinical value of pretreatment hormone levels for predicting invasive disease free survival (IDFS), skeletal recurrence and distant recurrence and response to treatment with zoledronic acid.

RESULTS

Oestradiol in the postmenopausal range (<50 pmol/l) was associated with a significantly shorter IDFS (HR 1.36 95%CI: 1.05-1.78 p=0.022), predominantly due to distant recurrence (HR 1.33 95%CI: 0.98-1.81 p=0.065), compared to oestradiol ≥50pmol/l. In contrast, FSH in the postmenopausal range (>26 IU/l) was associated with a longer time to bone as first recurrence (HR 0.66 95%CI: 0.41-1.04 p=0.072) compared to an FSH ≤26 IU/l. When all 3 hormone levels were within the assay specified postmenopausal range, a trend to improved IDFS was seen with addition of zoledronic acid in biochemically postmenopausal women only (postmenopausal HR=0.81; 95%CI: 0.54-1.22, non-postmenopausal HR=0.99; 95%CI: 0.69-1.39) with risk reductions that mirrored the results of the main AZURE study, although the interaction between menopausal status and treatment effect was not statistically significant (p=0.47).

CONCLUSION

Oestradiol and FSH may influence the pattern of disease recurrence with postmenopausal levels possibly creating a less conducive environment for the formation of bone metastases, therefore disseminated tumour cells could seek alternative niches outside of bone. Biochemical evaluation of a panel of reproductive hormones may be helpful to assist selection of patients for adjuvant zoledronic acid when menopausal status is unknown.

Treatment of Minimal Residual Disease in Breast Cancer: A Longitudinal Case Study

The presence of micrometastatic disease will ultimately determine the breast cancer-specific mortality of patients treated according to current guidelines. Minimal residual disease (i.e., occult tumor, not detected by conventional tests) may exist in two forms: a dormant form of only micrometastasis and a more aggressive “awakened” form where CTCs (circulating tumor cells) are actively disseminating. The hypothesis is that patients with CTCs have a more advanced or aggressive disease (that the cancer has “awoken” and there is active dissemination), whereas those patients with only micrometastasis have “dormant” disease and, although at risk of future relapse, may not do so for many years. This case study shows how determining the presence of both CTCs and bone marrow micrometastasis could be used to monitor disease activity and determine treatment changes before the appearance of metastatic disease.

Presented is the case of a 53-year-old postmenopausal woman who presented with a T2N1M0 invasive ductal breast cancer. She had been treated with partial mastectomy, axillary dissection, local radiotherapy, and adjuvant chemotherapy. As the cancer was estrogen receptor-positive, she was taking tamoxifen. Two years into treatment, she was assessed for minimal residual disease and was found to be positive for CTCs and bone marrow micrometastasis. Her treatment was changed to letrozole and differing bisphosphonates. The minimal residual disease was finally eliminated, and at 16 years post-initial treatment, there was no evidence of relapse.

The detection of minimal residual disease can be used to monitor treatment effect and change therapy in order to maintain the asymptomatic status of the patient and prevent disease progression.

Therapeutic Bone-Modifying Agents in the Nonmetastatic Breast Cancer Setting: The Controversy and a Value Assessment

Clinical trials and meta-analyses investigating bisphosphonates as an adjuvant breast cancer therapy have shown a consistent trend, with postmenopausal women and women receiving ovarian suppression with gonadotropin-releasing hormone therapy gaining improved breast cancer outcomes with the use of adjuvant bisphosphonate therapy. The interpretation of these data is controversial, because the primary endpoints of the majority of adjuvant bisphosphonate studies have been negative. Pros and cons as well as the value of adjuvant bisphosphonate therapy are discussed here.

Bisphosphonate-Functionalized Imaging Agents, Anti-Tumor Agents and Nanocarriers for Treatment of Bone Cancer

Bone metastases result from the invasion of primary tumors to bone. Current treatment modalities include local treatments such as surgery and radiotherapy, while systemic treatments include chemotherapy and (palliative) treatment of skeletal metastases. Nevertheless, once bone metastases have been established they remain incurable leading to morbidity and mortality. Bisphosphonates are a well-established class of drugs, which are increasingly applied in the treatment of bone cancers owing to their effective inhibition of tumor cells and suppression of bone metastases. The increased understanding of the mechanism of action of bisphosphonates on bone and tumor cells has prompted the development of novel bisphosphonate-functionalized imaging and therapeutic agents. This review provides an update on the preclinical efficacy of bisphosphonate-functionalized fluorophore, anti-tumor agents and nanocarriers for the treatment of bone metastases. After an overview of the general characteristics of bisphosphonates and their mechanisms of action, an outline is provided on the various conjugation strategies that have become available to functionalize imaging agents, anti-tumor agents and nanocarriers with bisphosphonates. Finally, the efficacy of these bisphosphonate-modified agents and carriers in preclinical studies is evaluated by reviewing their potential to target tumors and inhibit tumor growth in clinically relevant animal models for the treatment of bone cancer.

Circulating and disseminated tumor cells: harbingers or initiators of metastasis?

Tumor cells leave the primary tumor and enter the circulation. Once there, they are called circulating tumor cells (CTCs). A fraction of CTCs are capable of entering distant sites and persisting as disseminated tumor cells (DTCs). An even smaller fraction of DTCs are capable of progressing toward metastases. It is known that the DTC microenvironment plays an important role in sustaining their survival, regulating their growth, and conferring resistance to therapy. But we still have much to learn about the nature of these rare cell populations to predict which will progress and what exactly should cause concern for future relapse. Although recent technological advances in our ability to detect and molecularly and functionally characterize CTCs and DTCs promise to unravel this ambiguity, the timing of dissemination and the precise source of CTCs and DTCs profiled will impact the conclusions that can be made from these endeavors. In this review, we discuss the biology of CTCs and DTCs; the technologies to detect, isolate, and profile these cells; and the exceptions we must apply to our understanding of what role these cells play in the metastatic process. We conclude that a greater effort to understand the unique biology of these cells in context will positively impact our ability to use these cells to predict outcome, monitor treatment efficacy, and reveal therapeutically relevant targets to deplete these populations and ultimately prevent metastasis.

Reproductive hormones in breast cancer bone metastasis: The role of inhibins

The spread of breast cancer cells to bone and survival in this new metastatic environment is influenced not only by the genetic signature of the cells, but also multiple host cells and soluble factors produced locally (paracrine) or from distant sites (endocrine). Disrupting this metastatic process has been evaluated in clinical trials of the bone targeted agents bisphosphonates and denosumab and have shown that these agents reduce the recurrence of breast cancer in postmenopausal women only, suggesting the efficacy of the drugs are influenced by levels of reproductive endocrine hormones. The molecular mechanism driving this differential effect has not been definitively identified, however, there is evidence that both reproductive hormones and bisphosphonates can affect similar paracrine factors and cellular components of the bone metastatic niche. This review focuses on how the ovarian endocrine hormone, inhibin, interacts with the paracrine factors activin and follistatin, abundant in the primary tumour and bone microenvironment, with subsequent effects on tumour cell survival. Inhibin also affects the cellular components of the bone microenvironment primarily the osteoblastic niche. Recent evidence has shown that bisphosphonates also alter this niche, which may represent a common mechanism by which inhibin and bisphosphonates interact to influence disease outcomes in early breast cancer. Further research is needed to fully elucidate these molecular mechanisms to enable understanding and future development of alternative bone targeted treatments with anti-tumour efficacy in premenopausal women.

Different prognostic value of circulating and disseminated tumor cells in primary breast cancer: Influence of bisphosphonate intake?

Disseminated tumor cells (DTCs) in the bone marrow (BM) and circulating tumor cells (CTCs) in blood of breast cancer patients (pts) are known to correlate with worse outcome. Here we demonstrate a different prognostic value of DTCs and CTCs and explain these findings by early clodronate intake. CTCs (n = 376 pts) were determined using the AdnaTest BreastCancer (Qiagen Hannover GmbH, Germany) and DTCs (n = 525 pts) were analyzed by immunocytochemistry using the pan-cytokeratin antibody A45-B/B3. Clodronate intake was recommended in case of DTC-positivity. CTCs were detected in 22% and DTCs in 40% of the pts, respectively. DTCs were significantly associated with nodal status (p = 0.03), grading (p = 0.01), lymphangiosis (p = 0.03), PR status (p = 0.02) and clodronate intake (p < 0.0001), no significant associations were demonstrated for CTCs. CTCs significantly correlated with reduced PFS (p = 0.0227) and negative prognostic relevance was predominantly related to G2 tumors (p = 0.044), the lobular (p = 0.024) and the triple-negative subtype (p = 0.005), HR-negative pts (p = 0.001), postmenopausal women (p = 0.013) and patients who had received radiation therapy (p = 0.018). No prognostic significance was found for DTCs. Therefore early clodronate intake can improve prognosis of breast cancer patients and CTCs might be a high risk indicator for the onset of metastasis not limited to bone metastasis.

Disseminated tumor cells and dormancy in prostate cancer metastasis

It has been reported that disseminated tumor cells (DTCs) can be found in the majority of prostate cancer (PCa) patients, even at the time of primary treatment with no clinical evidence of metastatic disease. This suggests that these cells escaped the primary tumor early in the disease and exist in a dormant state in distant organs until they develop in some patients as overt metastases. Understanding the mechanisms by which cancer cells exit the primary tumor, survive the circulation, settle in a distant organ, and exist in a quiescent state is critical to understanding tumorigenesis, developing new prognostic assays, and designing new therapeutic modalities to prevent and treat clinical metastases.

Does primary neoadjuvant systemic therapy eradicate minimal residual disease? Analysis of disseminated and circulating tumor cells before and after therapy

BACKGROUND

Patients with breast cancer (BC) undergoing neoadjuvant chemotherapy (NACT) may experience metastatic relapse despite achieving a pathologic complete response. We analyzed patients with BC before and after NACT for disseminated tumor cells (DTCs) in the bone marrow(BM); comprehensively characterized circulating tumor cells (CTCs), including stem cell-like CTCs (slCTCs), in blood to prove the effectiveness of treatment on these cells; and correlated these findings with response to therapy, progression-free survival (PFS), and overall survival (OS).

METHODS

CTCs (n = 135) and slCTCs (n = 91) before and after NACT were analyzed using the AdnaTest BreastCancer, AdnaTest TumorStemCell, and epithelial-mesenchymal transition (QIAGEN Hannover GmbH Germany). The expression of estrogen receptor, progesterone receptor, and the resistance marker excision repair cross-complementing rodent repair deficiency, complementation group 1 (ERCC1), nuclease were studied in separate single-plex reverse transcription polymerase chain reaction experiments. DTCs were evaluated in 142 patients before and 165 patients after NACT using the pan-cytokeratin antibody A45-B/B3 for immunocytochemistry.

RESULTS

The positivity rates for DTCs, CTCs, and slCTCs were 27 %, 24 %, and 51 % before and 20 %, 8 %, and 20 % after NACT, respectively. Interestingly, 72 % of CTCs present after therapy were positive for ERCC1, and CTCs before (p = 0.005) and after NACT (p = 0.05) were significantly associated with the presence of slCTCs. Whereas no significant associations with clinical parameters were found for CTCs and slCTCs, DTCs were significantly associated with nodal status (p = 0.03) and histology (0.046) before NACT and with the immunohistochemical subtype (p = 0.02) after NACT. Univariable Cox regression analysis revealed that age (p = 0.0065), tumor size before NACT (p = 0.0473), nodal status after NACT (p = 0.0137), and response to NACT (p = 0.0136) were significantly correlated with PFS, whereas age (p = 0.0162) and nodal status after NACT (p = 0.0243) were significantly associated with OS. No significant correlations were found for DTCs or any CTCs before and after therapy with regard to PFS and OS.

CONCLUSIONS

Although CTCs were eradicated more effectively than DTCs, CTCs detected after treatment seemed to be associated with tumor cells showing tumor stem cell characteristics as well as with resistant tumor cell populations that might indicate a worse outcome in the future. Thus, these patients might benefit from additional second-line treatment protocols including bisphosphonates for the eradication of DTCs.

Adjuvant bisphosphonates in early breast cancer: consensus guidance for clinical practice from a European Panel

Bisphosphonates have been studied in randomised trials in early breast cancer to investigate their ability to prevent cancer treatment-induced bone loss (CTIBL) and reduce the risk of disease recurrence and metastasis. Treatment benefits have been reported but bisphosphonates do not currently have regulatory approval for either of these potential indications. This consensus paper provides a review of the evidence and offers guidance to breast cancer clinicians on the use of bisphosphonates in early breast cancer. Using the nominal group methodology for consensus, a systematic review of the literature was augmented by a workshop held in October 2014 for breast cancer and bone specialists to present and debate the available pre-clinical and clinical evidence for the use of adjuvant bisphosphonates. This was followed by a questionnaire to all members of the writing committee to identify areas of consensus. The panel recommended that bisphosphonates should be considered as part of routine clinical practice for the prevention of CTIBL in all patients with a T score of <-2.0 or ≥2 clinical risk factors for fracture. Compelling evidence from a meta-analysis of trial data of >18,000 patients supports clinically significant benefits of bisphosphonates on the development of bone metastases and breast cancer mortality in post-menopausal women or those receiving ovarian suppression therapy. Therefore, the panel recommends that bisphosphonates (either intravenous zoledronic acid or oral clodronate) are considered as part of the adjuvant breast cancer treatment in this population and the potential benefits and risks discussed with relevant patients.

Bisphosphonates for cancer treatment: Mechanisms of action and lessons from clinical trials

A growing body of evidence points toward an important anti-cancer effect of bisphosphonates, a group of inexpensive, safe, potent, and long-term stable pharmacologicals that are widely used as osteoporosis drugs. To date, they are already used in the prevention of complications of bone metastases. Because the bisphosphonates can also reduce mortality in among other multiple myeloma, breast, and prostate cancer patients, they are now thoroughly studied in oncology. In particular, the more potent nitrogen-containing bisphosphonates have the potential to improve prognosis. The first part of this review will elaborate on the direct and indirect anti-tumoral effects of bisphosphonates, including induction of tumor cell apoptosis, inhibition of tumor cell adhesion and invasion, anti-angiogenesis, synergism with anti-neoplastic drugs, and enhancement of immune surveillance (e.g., through activation of γδ T cells and targeting macrophages). In the second part, we shed light on the current clinical position of bisphosphonates in the treatment of hematological and solid malignancies, as well as on ongoing and completed clinical trials investigating the therapeutic effect of bisphosphonates in cancer. Based on these recent data, the role of bisphosphonates is expected to further expand in the near future outside the field of osteoporosis and to open up new avenues in the treatment of malignancies.

The biology and clinical implications of prostate cancer dormancy and metastasis

Disseminated tumor cells (DTCs) are detected early in the disease process in prostate cancer (PCa) patients and can persist after radical prostatectomy. DTCs can remain dormant in patients with no evidence of disease for a prolonged period of time only to recur 10 or more years later. Recent advances in single-cell genomics and transcriptomics have provided much needed insight into DTC biology and cancer dormancy in patients. With the development of new in vitro and preclinical models, researchers recapitulate the clinical events in patients and therefore allow further elucidation of the molecular mechanisms underlying cancer dormancy and escape. In this review, we explore novel ideas on the detection, heterogeneous transcriptomic profiles, molecular and cellular mechanisms of dormancy, and potential mechanisms underlying dormancy escape by DTCs. As such, there is hope that identifying and targeting novel dormancy-associated pathways in patients with residual disease will have significant clinical implications for the treatment of PCa patients in the future.

Bone antiresorptive agents in the treatment of bone metastases associated with solid tumours or multiple myeloma

Skeletal lesions contribute substantially to morbidity and mortality in patients with cancer. The disease manifestation course during metastatic bone disease is driven by tumour cells in the bone marrow, which alter the functions of bone-resorbing (osteoclasts) and bone-forming (osteoblasts) cells, promoting skeletal destruction. Successful therapeutic strategies for the treatment of metastatic bone disease include bisphosphonates and denosumab that inhibit osteoclast-mediated bone resorption. Inhibitors of cathepsin K, Src and activin A are under clinical investigation as potential anti-osteolytics. In this review, we describe current knowledge and future directions of antiresorptive therapies that may reduce or prevent destructive bone lesions from solid tumours and multiple myeloma.

Bisphosphonates as anticancer agents in early breast cancer: preclinical and clinical evidence

Bisphosphonates (BPs) are approved as standard therapy in breast cancer for the treatment of bone metastases, since they were demonstrated to reduce the prevalence of skeletal-related events including fractures and hypercalcemia. In the adjuvant setting, BPs can be given to prevent and treat tumor therapy-induced bone loss in premenopausal and postmenopausal women and, owing to their beneficial effect on bone turnover, have also been evaluated for prevention of bone metastases occurrence. In this article we will review the mechanisms through which BPs have been demonstrated to prevent premetastatic niche formation and cell proliferation in bone lesions. Moreover, preclinical evidence of antitumoral effects of BPs will be presented and results from the most important clinical trials will be described critically. BPs may clearly play a clinically important role in early breast cancer in a postmenopausal adjuvant setting.

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.