Bisphosphonates or RANK-ligand-inhibitors for men with prostate cancer and bone metastases: a network meta-analysis

Administration and cancer-control outcomes of bone-modifying agents in real-world patients with metastatic castration-resistant prostate cancer

Hormonal agents administered for metastatic castration-resistant prostate cancer (mCRPC) may lead to osteoporosis, skeletal events, reduced quality of life, and even reduced overall survival (OS). Bone-modifying agents may prevent those events but their effect on cancer-control outcomes remains uncertain. Relying on our institutional tertiary-care database, we explored the effect of bone-modifying agents (bisphosphonates such as zoledronic acid and denosumab) on OS and progression-free survival in patients with mCRPC with at least 1 bone metastasis using Kaplan-Meyer estimates and Cox regression models. Of 420 patients with mCRPC, 60% received bone-modifying agents who were younger (68 vs 69 years), with more systemic treatment lines for mCRPC (3 vs 2), and a higher proportion of initial de novo metastatic disease (72% vs 62%, all p ≤ .04) than patients without bone-modifying agents. In progression-free survival analyses, no significant differences were observed between both groups. In OS analyses, significant median OS differences were observed in favor of patients with bone-modifying agents (58 vs 45 months; hazard ratio [HR]: 0.66), even after multivariable adjustment (HR: 0.37; both p ≤ .01). In bone-modifying agent-stratified analyses, 57% received denosumab vs 43% bisphosphonates, with a significantly higher rate of Eastern Cooperative Oncology Group status of ≥2 in the bisphosphonates group. In progression-free and OS analyses, no significant differences were observed between bisphosphonates and denosumab patients, with numerically better results in progression-free survival analysis for denosumab after adjusting for covariates. The cumulative rate of osteonecrosis of the jaw at any treatment time was 12% in both groups and significantly decreased over time. Real-world data suggest a relatively low administration rate of bone-modifying agents in patients with osseous mCRPC. However, real-world data also suggest an OS benefit when bone-modifying agents are used, even after controlling for possible confounding patient and tumor characteristics.

Immunotherapy in the Fight Against Bone Metastases: A Review of Recent Developments and Challenges

OPINION STATEMENT

Bone metastasis, a frequent and detrimental complication of advanced cancers, often triggers bone deterioration events that severely compromise patient quality of life and prognosis. The past few years have witnessed the emergence and continuous advancements in immunotherapy, ushering in innovative therapeutic prospects for bone metastasis. These advancements include not only the use of immune checkpoint inhibitors (ICIs), both as standalone and combined treatments, but also the investigation of novel targets within immune cells residing in bone metastases. These breakthroughs have instilled fresh optimism for effectively managing patients with bone metastasis. This article endeavors to present an exhaustive review of the recent progress made across a spectrum of immunotherapeutic strategies and targeted therapies specifically designed for individuals battling bone metastasis from malignant tumors. By doing so, it seeks to offer insights that can inform clinical practices and guide further medical research in this domain.

Development of a core outcome set of clinical research on the integration of traditional Chinese and Western medicine for spinal metastases:

BACKGROUND

In recent years, the incidence of spinal metastasis (SM) has been increasing steadily. In response to this serious public health problem, researchers have made progress by using the integration of traditional Chinese and Western medicine. However, considerable heterogeneity in the definition and measurement of outcomes across clinical research studies, along with the lack of uniform measurement standards for study data, makes it difficult for researchers to compare different treatments. Therefore, it is crucial to accurately evaluate clinical research on the integration of traditional Chinese and Western medicine for SM.

METHODS

This study protocol outlines a comprehensive research programme based on the Core Outcome Set Standards Protocol Items. The study consists of four phases: a literature review, semistructured interviews, a two-round modified Delphi survey, a consensus meeting. Phase 1 involves a comprehensive literature review to extract outcomes used in current clinical studies of integrated traditional Chinese and Western medicine or Western medicine for the treatment of SM. A semistructured interview format will be used to survey patients and caregivers in phase 2 to collect suggestions from the patient perspective. Phase 3 involves a two-round modified Delphi survey to complete a prioritisation evaluation of outcomes to generate a candidate list for core outcome set (COS). Finally, phase 4 involves a face-to-face consensus meeting to review and establish the COS.

ETHICS AND DISSEMINATION

Conducted in response to the current dilemma of SM, the study was endorsed by the Spine Oncology Group of the Orthopaedic Surgeons Branch of the Chinese Physicians' Association. It will be developed and reported through a rigorous process, with the results of the study to be published in a peer-reviewed journal.Registration: COMET Registry: COMET 2938; https://www.comet-initiative.org/Studies/Details/2938.

The emerging role of osteoclasts in the treatment of bone metastases: rationale and recent clinical evidence

The occurrence of bone metastasis is a grave medical concern that substantially impacts the quality of life in patients with cancer. The precise mechanisms underlying bone metastasis remain unclear despite extensive research efforts, and efficacious therapeutic interventions are currently lacking. The ability of osteoclasts to degrade the bone matrix makes them a crucial factor in the development of bone metastasis. Osteoclasts are implicated in several aspects of bone metastasis, encompassing the formation of premetastatic microenvironment, suppression of the immune system, and reactivation of quiescent tumor cells. Contemporary clinical interventions targeting osteoclasts have proven effective in mitigating bone-related symptoms in patients with cancer. This review comprehensively analyzes the mechanistic involvement of osteoclasts in bone metastasis, delineates potential therapeutic targets associated with osteoclasts, and explores clinical evidence regarding interventions targeting osteoclasts.

Investigating the Underlying Molecular Mechanisms of Yunke on Bone Metastases from Prostate Cancer

Objective

To explore analgesic effect and bone repair mechanism of non-radioactive technetium-99 conjugated with methylene diphosphonate (99Tc-MDP, brand name, Yunke) on bone metastases (BM).

Procedures

In vivo experiment, mouse BM models of prostate cancer RM-1 cell were constructed and divided into Control, Yunke, 99Tc+SnCl2 and MDP groups based on medicine composition. Tumor specimens were inspected for size, X-ray, microCT and histopathology. In vitro experiment, with Cell Counting Kit-8 (CCK8), scratch, clone, apoptosis, Polymerase Chain Reaction (PCR) and Western Blot experiments, effects of Yunke on RM-1 cells and osteoclast-related cells were observed.

Results

In vivo experiment, there was no difference in tumor size between Yunke and control group. Contrasted with control group, in Yunke group, trabecular spacing (Tb.Sp) of tumor bone was lower, bone volume/total volume (BV/TV) on marrow cavity and bone cortex were higher. Tunnel staining showed that positive rate of apoptosis in Yunke group was higher than that in control group. Ki67 staining showed that Yunke could not inhibit proliferation of tumor cells. In vitro experiment, CCK8 and scratch experiments showed that Yunke neither can inhibit proliferation nor can inhibit migration of RM-1 cells. High concentration of Yunke promoted late apoptosis of RM-1 cells. Yunke could inhibit BMM cell proliferation, differentiation of osteoclasts, and osteoclast-related transcription factors. Yunke displayed different degrees of inhibitory effects on MAPKs signaling pathway during osteoclast differentiation. It had obvious inhibitory effects on osteoclast-related transcription factors, such as cFOS, NFATC1, ACP-5, CTSK, D2 and MMP-9, the strongest inhibitory effects were observed with ACP-5, CTSK and D2. Yunke also displayed different degrees of inhibitory effects on protein activities of JNK, pERK, ERK and pP38.

Conclusion

Yunke cannot inhibit the proliferation and migration of RM-1 cells, so we think it is not recommended for the treatment of primary tumors and prevention of occurrence of tumors metastatic to bones. The mechanism of therapeutic effect of Yunke on BM by inhibiting proliferation of BMM, inhibiting MAPKs signal transduction and activation of transcription factors during differentiation process of BMM-derived osteoclasts, inhibiting number and size of osteoclasts, inhibiting bone resorption and protecting bone destruction through enhancing bone hardness and bone mass. Thereby, we believe that Yunke is more suitable for promoting the repair induced by BMs, delaying its progression and reducing the occurrence of SREs.

Role of bisphosphonates in osteoporosis caused by adult growth hormone deficiency

In recent years, growth hormone and insulin-like growth factors have become key regulators of bone metabolism and remodeling, crucial for maintaining healthy bone mass throughout life. Studies have shown that adult growth hormone deficiency leads to alterations in bone remodeling, significantly affecting bone microarchitecture and increasing fracture risk. Although recombinant human growth hormone replacement therapy can mitigate these adverse effects, improving bone density, and reduce fracture risk, its effectiveness in treating osteoporosis, especially in adults with established growth hormone deficiency, seems limited. Bisphosphonates inhibit bone resorption by targeting farnesyl pyrophosphate synthase in osteoclasts, and clinical trials have confirmed their efficacy in improving osteoporosis. Therefore, for adult growth hormone deficiency patients with osteoporosis, the use of bisphosphonates alongside growth hormone replacement therapy is recommended.

Recent advances in the molecular targeted drugs for prostate cancer

CONTEXT

Prostate cancer (PCa) is the second largest male tumor in the world and one of the most common malignant tumors in the urinary system. In recent years, the incidence rate of PCa in China has been increasing year by year. Meanwhile, refractory hormone resistance and adverse drug reactions of advanced PCa cause serious harm to patients.

OBJECTIVE

The present study aims to systematically review the recent advances in molecularly targeted drugs for prostate cancer and to use the retrieval and analysis of the literature library to summarize the adverse effects of different drugs so as to maximize the treatment benefits of targeted therapies.

EVIDENCE ACQUISITION

We performed a systematic literature search of the Medline, EMBASE, PubMed, and Cochrane databases up to March 2022 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Medical Subject Heading (MeSH) terms and keywords such as (prostate cancer) AND (molecular target drugs) AND (side effect) were used. No language restrictions were set on the search process, and all these results were processed independently by two authors. Consensus was reached through discussion once met with any disagreements. The primary endpoint was differential features between different molecular targeted drugs. Secondary endpoints were side effects of different drugs on the body and corresponding prognostic values.

EVIDENCE SYNTHESIS

The Cochrane Collaboration risk of bias tool was used to assess the study quality in terms of sequence generation, allocation concealment, blinding, the completeness of outcome data, selective reporting and other biases. We retrieved 332 articles, of which 49 met the criteria for inclusion. Included studies show that prostatic tumor cells, tumor neovascularization and immune checkpoints are the main means for targeted therapy. Common drugs include 177 Lu-PSMA, Olaparib, Rucaparib, Bevacizumab, Pazopanib, Sorafenib, Cabozantinib, Aflibercept, Ipilimumab, Atezolizumab, Avelumab, Durvalumab. A series of publicly available data suitable for further analysis of side effects. An over-representation analysis of these datasets revealed reasonable dosage and usage is the key to controlling the side effects of targeted drugs. Important information such as the publication year, the first author, location and outcome observation of adverse effects was extracted from the original article. If the study data has some insufficient data, contacting the corresponding authors is necessary. All the studies included prospective nonrandomized and randomized research. Retrospective reviews were also screened according to the relevant to the purpose of this study. Meeting abstracts as well as letters to the editor and editorials were excluded.

STATISTICAL ANALYSIS

Data analysis was based on Cochrane's risk of bias tools to obtain the quality assessment. The included randomized studies used RoB2 and non-randomized ones corresponded to ROBINS-I. Standardized mean differences (SMD) were used to determine relative risk (RR) and side effects between groups. The eggers' test was used to check the publication bias from variable information in the included studies. All p < 0.05 were considered to be significant, and 95% was set as the confidence interval.

CONCLUSIONS

With the approval of a variety of targeted drugs, targeted therapy will be widely used in the treatment of advanced or metastatic prostate cancer. Despite the existence of adverse reactions related to targeted drug treatment, it is still meaningful to adjust the drug dosage or treatment cycle to reduce the occurrence of adverse reactions, improving the treatment benefits of patients.

Osteoid cell-derived chemokines drive bone-metastatic prostate cancer

One of the greatest challenges in improving prostate cancer (PCa) survival is in designing new therapies to effectively target bone metastases. PCa regulation of the bone environment has been well characterized; however, bone-targeted therapies have little impact on patient survival, demonstrating a need for understanding the complexities of the tumor-bone environment. Many factors contribute to creating a favorable microenvironment for prostate tumors in bone, including cell signaling proteins produced by osteoid cells. Specifically, there has been extensive evidence from both past and recent studies that emphasize the importance of chemokine signaling in promoting PCa progression in the bone environment. Chemokine-focused strategies present promising therapeutic options for treating bone metastasis. These signaling pathways are complex, with many being produced by (and exerting effects on) a plethora of different cell types, including stromal and tumor cells of the prostate tumor-bone microenvironment. ​This review highlights an underappreciated molecular family that should be interrogated for treatment of bone metastatic prostate cancer (BM-PCa).

Prostate cancer induced bone pain: pathobiology, current treatments and pain responses from recent clinical trials

PURPOSE

Metastatic spread of prostate cancer to the skeleton may result in debilitating bone pain. In this review, we address mechanisms underpinning the pathobiology of metastatic prostate cancer induced bone pain (PCIBP) that include sensitization and sprouting of primary afferent sensory nerve fibres in bone. We also review current treatments and pain responses evoked by various treatment modalities in clinical trials in this patient population.

METHODS

We reviewed the literature using PubMed to identify research on the pathobiology of PCIBP. Additionally, we reviewed clinical trials of various treatment modalities in patients with PCIBP with pain response outcomes published in the past 7 years.

RESULTS

Recent clinical trials show that radionuclides, given either alone or in combination with chemotherapy, evoked favourable pain responses in many patients and a single fraction of local external beam radiation therapy was as effective as multiple fractions. However, treatment with chemotherapy, small molecule inhibitors and/or immunotherapy agents, produced variable pain responses but pain response was the primary endpoint in only one of these trials. Additionally, there were no published trials of potentially novel analgesic agents in patients with PCIBP.

CONCLUSION

There is a knowledge gap for clinical trials of chemotherapy, small molecule inhibitors and/or immunotherapy in patients with PCIBP where pain response is the primary endpoint. Also, there are no novel analgesic agents on the horizon for the relief of PCIBP and this is an area of large unmet medical need that warrants concerted research attention.

Oral-Health-Related Quality of Life in Patients with Medication-Related Osteonecrosis of the Jaw: A Prospective Clinical Study

Medication-related osteonecrosis of the jaw (MRONJ) represents an adverse side effect of antiresorptive and antiangiogenic medications. It is associated with impaired quality of life, oral health, and oral function and can be classified into various stages. The purpose of this prospective clinical study is to evaluate the impact of stages I and II MRONJ on oral-health-related quality of life (OHRQoL) and related parameters. Patients' OHRQoL, satisfaction with life, oral discomfort, and oral health were assessed using the German version of the Oral Health Impact Profile (OHIP-G49), visual analog scales (VAS), and Satisfaction with Life Scale (SWLS) at baseline (T0), 10 days (T1), and 3 months after treatment (T2) in 36 patients. Data were analyzed using Kolmogorov-Smirnov test, two-way mixed ANOVAs, and follow-up Mann-Whitney U tests. The impact of treatment effects on the original seven OHIP domain structures and the recently introduced four-dimensional OHIP structure were evaluated using linear regression analysis. Thirty-six patients received surgical MRONJ treatment. Before treatment, patients' perceived OHRQoL, oral discomfort, oral health, and satisfaction with life were negatively affected by MRONJ. Surgical treatment significantly improved OHRQoL and related parameters (all p ≤ 0.012). This improvement was greater in patients with higher impairment at T0. OHRQoL and oral restrictions were still impaired after treatment in patients who needed prosthetic treatment. The four-dimensional structure revealed valuable information beyond the standard seven OHIP domains. Increased awareness of MRONJ risks and an interdisciplinary treatment approach for MRONJ patients are needed.

Palliative radiotherapy of bone metastases in octogenarians: How do the oldest olds respond? Results from a tertiary cancer center with 288 treated patients

BACKGROUND

Accompanied by the demographic change, the number of octogenarian cancer patients with bone metastases will increase in the future. Palliative radiotherapy constitutes an effective analgesic treatment; however, as pain perception and bone metabolism change with increasing age, the analgesic efficacy of radiotherapy may be altered in elderly patients. We therefore investigated the treatment outcomes of palliative radiotherapy for bone metastases in octogenarians.

METHODS

Patients between 80 and 89 years undergoing radiotherapy for bone metastases between 2009 and 2019 at a tertiary cancer center were analyzed for patterns-of-care, pain response and overall survival (OS). Logistic regression analyses were carried out to examine parameters associated with pain response, and Cox analyses were conducted to reveal prognostic parameters for OS.

RESULTS

A total of 288 patients with 516 irradiated lesions were included in the analysis. The majority (n = 249, 86%) completed all courses of radiotherapy. Radiotherapy led to pain reduction in 176 patients (61%) at the end of treatment. Complete pain relief at the first follow-up was achieved in 84 patients (29%). Bisphosphonate administration was significantly associated with higher rates of pain response at the first follow-up (p < 0.05). Median OS amounted to 9 months, and 1-year, 2-year and 3-year OS were 43%, 28% and 17%. In the multivariate analysis, ECOG (p < 0.001), Mizumoto score (p < 0.01) and Spinal Instability Neoplastic Score (SINS) (p < 0.001) were independent prognosticators for OS.

CONCLUSION

Palliative radiotherapy for bone metastases constitutes a feasible and effective analgesic treatment in octogenarian patients. ECOG, Mizumoto score and SINS are prognosic variables for survival and may aid treatment decisions regarding radiotherapy fractionation in this patient group. Single-fraction radiotherapy with 8 Gy should be applied for patients with uncomplicated bone metastases and poor prognosis. Prospective trials focusing on quality of life of these very old cancer patients with bone metastases are warranted to reveal the optimal radiotherapeutic management for this vulnerable population.

Bone Health Management in the Continuum of Prostate Cancer Disease

Prostate cancer (PCa) is the second-leading cause of cancer-related deaths in men. PCa cells require androgen receptor (AR) signaling for their growth and survival. Androgen deprivation therapy (ADT) is the preferred treatment for patients with locally advanced and metastatic PCa disease. Despite their initial response to androgen blockade, most patients eventually will develop metastatic castration-resistant prostate cancer (mCRPC). Bone metastases are common in men with mCRPC, occurring in 30% of patients within 2 years of castration resistance and in >90% of patients over the course of the disease. Patients with mCRPC-induced bone metastasis develop lesions throughout their skeleton; the 5-year survival rate for these patients is 47%. Bone-metastasis-induced early changes in the bone that proceed the osteoblastic response in the bone matrix are monitored and detected via modern magnetic resonance and PET/CT imaging technologies. Various treatment options, such as targeting osteolytic metastasis with bisphosphonates, prednisone, dexamethasone, denosumab, immunotherapy, external beam radiation therapy, radiopharmaceuticals, surgery, and pain medications are employed to treat prostate-cancer-induced bone metastasis and manage bone health. However, these diagnostics and treatment options are not very accurate nor efficient enough to treat bone metastases and manage bone health. In this review, we present the pathogenesis of PCa-induced bone metastasis, its deleterious impacts on vital organs, the impact of metastatic PCa on bone health, treatment interventions for bone metastasis and management of bone- and skeletal-related events, and possible current and future therapeutic options for bone management in the continuum of prostate cancer disease.

Osteoclasts directly influence castration-resistant prostate cancer cells

Metastasis to bone is the leading cause of death from prostate cancer. Interaction between tumor cells and bone cells can promote progression and influence tumor phenotype. It is known that prostate cancer cells support osteoclast differentiation, and degradation of bone matrix by osteoclasts releases growth factors stimulating tumor cell proliferation and invasion. In the present study osteolytic (PC-3) and osteoblastic (LNCaP-19) castration-resistant prostate cancer (CRPC) cells were co-cultured with mature osteoclasts or their precursor cells (RAW 264.7) to characterize direct effects of mature osteoclasts on CRPC cells. Osteoclasts increased proliferation and decrease apoptosis of CRPC cells as assessed with flow cytometry. RNA sequencing revealed that osteolytic CRPC cells were more responsive to osteoclast stimulation regarding gene expression, but the overall induced expression patterns were similar between the prostate cancer cell lines. Genes related to DNA repair were upregulated by osteoclasts, while genes related to endoplasmic reticulum stress-induced apoptosis and cholesterol synthesis were downregulated. The results of this study shows that osteoclasts directly influence CRPC cells, increasing proliferation, decreasing apoptosis, and affecting gene expression pathways that can affect sensitivity to DNA damage and endoplasmic reticulum function. This suggests targeting of osteoclasts to be a possible way to affect efficacy of other drugs by combination regimens in treating prostate cancer metastases.

Bone health and therapeutic agents in advanced prostate cancer

Prostate cancer is the most frequent genitourinary tumor worldwide. Maintaining an optimum bone health throughout the natural course of prostate cancer is an important aspect in the management of this disease, particularly in this at risk population of older and frail patients who experience bone loss related to androgen-deprivation therapy (ADT) and/or patients who develop bone metastases. The number of treatment options for advanced prostate cancer that combine ADT with docetaxel, new hormonal agents and/or radiotherapy has increased substantially in recent years. Bisphosphonates and other bone targeted agents such as denosumab have shown an improvement in bone mineral density and are suited for patients with treatment-related osteoporosis and/or bone metastases with an increased risk of skeletal-related events (SREs). In this context, the aim of this review is to analyse key aspects of bone health and therapies that can prevent the occurrence of SREs throughout the clinical course of prostate cancer, and how to combine them with new available treatments in this setting.

Macrophages as a Therapeutic Target in Metastatic Prostate Cancer: A Way to Overcome Immunotherapy Resistance?

Prostate cancer (PC) is the most common malignancy and the fifth cause of cancer death in men. The treatment for localized or locally advanced stages offers a high probability of cure. Even though the therapeutic landscape has significantly improved over the last decade, metastatic PC (mPC) still has a poor prognosis mainly due to the development of therapy resistance. In this context, the use of immunotherapy alone or in combination with other drugs has been explored in recent years. However, T-cell directed immune checkpoint inhibitors (ICIs) have shown limited activity with inconclusive results in mPC patients, most likely due to the highly immunosuppressive PC tumor microenvironment (TME). In this scenario, targeting macrophages, a highly abundant immunosuppressive cell type in the TME, could offer a new therapeutic strategy to improve immunotherapy efficacy. In this review, we summarize the growing field of macrophage-directed immunotherapies and discuss how these could be applied in the treatment of mPC, focusing on their combination with ICIs.

The Efficacy of Denosumab in Patients With Rheumatoid Arthritis: A Systematic Review and Pooled Analysis of Randomized or Matched Data

Objective

The purpose of this study was to evaluate the efficacy of denosumab treatment in patients with rheumatoid arthritis (RA).

Methods

The Medline, Embase and Cochrane Library databases were searched for relevant clinical studies. Studies that assessed the efficacy of denosumab in patients with RA were identified. The primary endpoints were the percent changes in bone mineral density (BMD), and the changes in modified total Sharp score (mTSS), modified Sharp erosion score and joint space narrowing (JSN) score. Pooled analyses were calculated using random-effect models.

Results

After searching the literature and performing further detailed assessments, 10 studies with a total of 1758 patients were included in the quantitative analysis. Pooled analyses showed that denosumab treatment significantly increased the percent changes in lumbar spine BMD [mean difference (MD): 5.12, confidence intervals (CI): 4.15 to 6.09], total hip BMD (MD: 2.72, 95% CI: 1.80 to 3.64) and femoral neck BMD (MD: 2.20, 95% CI: 0.94 to 3.46) compared with controls. Moreover, denosumab treatment significantly decreased the changes in mTSS (MD: -0.63, 95% CI: -0.86 to -0.41) and modified Sharp erosion score (MD: -0.62, 95% CI: -0.88 to -0.35). Subgroup analysis indicated that denosumab was superior to bisphosphonates for the improvement of BMD and the mitigation of joint destruction.

Conclusion

Denosumab treatment was associated with increased BMD and alleviated progression of joint destruction in RA patients, even when compared with bisphosphonates.

Bone-modifying agents for bone loss in patients with prostate cancer receiving androgen deprivation therapy; insights from a network meta-analysis

BACKGROUND

The data of head-to-head comparisons of the effect of bone-modifying agents (BMAs) in patients with androgen deprivation therapy (ADT) for prostate cancer without skeletal metastasis is limited. Thus, we conducted a network meta-analysis to compare each BMA for the efficacy of bone mineral densities (BMDs) and the risk of fracture.

METHODS

We performed a network meta-analysis to compare the change of BMDs and the risk of vertebral fracture in the studies included using a random-effect model. The primary outcomes are the change of BMD of the lumbar spine (LS) and the total hip (TH) from the baseline at 1 year from the initiation of the BMA and the risk of vertebral fracture.

RESULTS

We identified and included 15 studies in this analysis. All BMAs except risedronate showed a significant increase of BMD of the LS compared with groups without BMA, among which zoledronate showed the most BMD gain. At TH, bisphosphonates (alendronate, pamidronate, and zoledronate) and denosumab showed significant elevation compared with the no-BMA group. Denosumab was associated with the most BMD gain at the TH. Only denosumab reduced the risk of vertebral fracture (relative risk [95% confidence interval]: 0.40 [0.20-0.81]). Although zoledronate showed the highest BMD gain at the LS, it did not reduce the risk of vertebral fracture in this analysis.

CONCLUSION

Most bisphosphonates and denosumab significantly increased BMD at the LS and the TH in patients receiving ADT for prostate cancer without skeletal metastasis. In particular, zoledronate and denosumab were the most potent BMAs in terms of BMD increment at the LS and the TH, respectively. However, denosumab, not zoledronate, was the only BMA that showed a significant risk reduction of vertebral fracture. We need further studies to examine the change of bone quality and the effect on the risk of non-vertebral and hip fractures.

Cross Talk Between Macrophages and Cancer Cells in the Bone Metastatic Environment

The skeleton is a common site for cancer metastases with the bone microenvironment providing the appropriate conditions for cancer cell colonization. Once in bone, cancer cells effectively manipulate their microenvironment to support their growth and survival. Despite previous efforts to improve treatment modalities, skeletal metastases remain with poor prognoses. This warrants an improved understanding of the mechanisms leading to bone metastasis that will aid development of effective treatments. Macrophages in the tumor microenvironment are termed tumor associated macrophages (TAMs) and their crosstalk with cancer cells is critical in regulating tumorigenicity in multiple cancers. In bone metastases, this crosstalk is also being increasingly implicated but the specific signaling pathways remain incompletely understood. Here, we summarize the reported functions, interactions, and signaling of macrophages with cancer cells during the metastatic cascade to bone. Specifically, we review and discuss how these specific interactions impact macrophages and their profiles to promote tumor development. We also discuss the potential of targeting this crosstalk to inhibit disease progression. Finally, we identify the remaining knowledge gaps that will need to be addressed in order to fully consider therapeutic targeting to improve clinical outcomes in cancer patients.

Osteoimmuno-Oncology: Therapeutic Opportunities for Targeting Immune Cells in Bone Metastasis

Immunotherapies provide a potential treatment option for currently incurable bone metastases. Bone marrow is an important secondary lymphoid organ with a unique immune contexture. Even at non-disease state immune cells and bone cells interact with each other, bone cells supporting the development of immune cells and immune cells regulating bone turnover. In cancer, tumor cells interfere with this homeostatic process starting from formation of pre-metastatic niche and later supporting growth of bone metastases. In this review, we introduce a novel concept osteoimmuno-oncology (OIO), which refers to interactions between bone, immune and tumor cells in bone metastatic microenvironment. We also discuss therapeutic opportunities of targeting immune cells in bone metastases, and associated efficacy and safety concerns.

Medication-Related Osteonecrosis of the Jaw (MRONJ): Are Antiresorptive Drugs the Main Culprits or Only Accomplices? The Triggering Role of Vitamin D Deficiency

Osteonecrosis of the jaw (ONJ) is a severe clinical condition characterized mostly but not exclusively by an area of exposed bone in the mandible and/or maxilla that typically does not heal over a period of 6-8 weeks. The diagnosis is first of all clinical, but an imaging feedback such as Magnetic Resonance is essential to confirm clinical suspicions. In the last few decades, medication-related osteonecrosis of the jaw (MRONJ) has been widely discussed. From the first case reported in 2003, many case series and reviews have appeared in the scientific literature. Almost all papers concerning this topic conclude that bisphosphonates (BPs) can induce this severe clinical condition, particularly in cancer patients. Nevertheless, the exact mechanism by which amino-BPs would be responsible for ONJ is still debatable. Recent findings suggest a possible alternative explanation for BPs role in this pattern. In the present work we discuss how a condition of osteomalacia and low vitamin D levels might be determinant factors.

(2-Aminobenzothiazole)-Methyl-1,1-Bisphosphonic Acids: Targeting Matrix Metalloproteinase 13 Inhibition to the Bone

Matrix Metalloproteinases (MMPs) are a family of secreted and membrane-bound enzymes, of which 24 isoforms are known in humans. These enzymes degrade the proteins of the extracellular matrix and play a role of utmost importance in the physiological remodeling of all tissues. However, certain MMPs, such as MMP-2, -9, and -13, can be overexpressed in pathological states, including cancer and metastasis. Consequently, the development of MMP inhibitors (MMPIs) has been explored for a long time as a strategy to prevent and hinder metastatic growth, but the important side effects linked to promiscuous inhibition of MMPs prevented the clinical use of MMPIs. Therefore, several strategies were proposed to improve the therapeutic profile of this pharmaceutical class, including improved selectivity toward specific MMP isoforms and targeting of specific organs and tissues. Combining both approaches, we conducted the synthesis and preliminary biological evaluation of a series of (2-aminobenzothiazole)-methyl-1,1-bisphosphonic acids active as selective inhibitors of MMP-13 via in vitro and in silico studies, which could prove useful for the treatment of bone metastases thanks to the bone-targeting capabilities granted by the bisphosphonic acid group.

Bisphosphonates or RANK-ligand-inhibitors for men with prostate cancer and bone metastases: a network meta-analysis

BACKGROUND

Different bone-modifying agents like bisphosphonates and receptor activator of nuclear factor-kappa B ligand (RANKL)-inhibitors are used as supportive treatment in men with prostate cancer and bone metastases to prevent skeletal-related events (SREs). SREs such as pathologic fractures, spinal cord compression, surgery and radiotherapy to the bone, and hypercalcemia lead to morbidity, a poor performance status, and impaired quality of life. Efficacy and acceptability of the bone-targeted therapy is therefore of high relevance. Until now recommendations in guidelines on which bone-modifying agents should be used are rare and inconsistent.

OBJECTIVES

To assess the effects of bisphosphonates and RANKL-inhibitors as supportive treatment for prostate cancer patients with bone metastases and to generate a clinically meaningful treatment ranking according to their safety and efficacy using network meta-analysis.

SEARCH METHODS

We identified studies by electronically searching the bibliographic databases Cochrane Controlled Register of Trials (CENTRAL), MEDLINE, and Embase until 23 March 2020. We searched the Cochrane Library and various trial registries and screened abstracts of conference proceedings and reference lists of identified trials.

SELECTION CRITERIA

We included randomized controlled trials comparing different bisphosphonates and RANKL-inihibitors with each other or against no further treatment or placebo for men with prostate cancer and bone metastases. We included men with castration-restrictive and castration-sensitive prostate cancer and conducted subgroup analyses according to this criteria.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the quality of trials. We defined proportion of participants with pain response and the adverse events renal impairment and osteonecrosis of the jaw (ONJ) as the primary outcomes. Secondary outcomes were SREs in total and each separately (see above), mortality, quality of life, and further adverse events such as grade 3 to 4 adverse events, hypocalcemia, fatigue, diarrhea, and nausea. We conducted network meta-analysis and generated treatment rankings for all outcomes, except quality of life due to insufficient reporting on this outcome. We compiled ranking plots to compare single outcomes of efficacy against outcomes of acceptability of the bone-modifying agents. We assessed the certainty of the evidence for the main outcomes using the GRADE approach.

MAIN RESULTS

Twenty-five trials fulfilled our inclusion criteria. Twenty-one trials could be considered in the quantitative analysis, of which six bisphosphonates (zoledronic acid, risedronate, pamidronate, alendronate, etidronate, or clodronate) were compared with each other, the RANKL-inhibitor denosumab, or no treatment/placebo. By conducting network meta-analysis we were able to compare all of these reported agents directly and/or indirectly within the network for each outcome. In the abstract only the comparisons of zoledronic acid and denosumab against the main comparator (no treatment/placebo) are described for outcomes that were predefined as most relevant and that also appear in the 'Summary of findings' table. Other results, as well as results of subgroup analyses regarding castration status of participants, are displayed in the Results section of the full text. Treatment with zoledronic acid probably neither reduces nor increases the proportion of participants with pain response when compared to no treatment/placebo (risk ratio (RR) 1.46, 95% confidence interval (CI) 0.93 to 2.32; per 1000 participants 121 more (19 less to 349 more); moderate-certainty evidence; network based on 4 trials including 1013 participants). For this outcome none of the trials reported results for the comparison with denosumab. The adverse event renal impairment probably occurs more often when treated with zoledronic acid compared to treatment/placebo (RR 1.63, 95% CI 1.08 to 2.45; per 1000 participants 78 more (10 more to 180 more); moderate-certainty evidence; network based on 6 trials including 1769 participants). Results for denosumab could not be included for this outcome, since zero events cannot be considered in the network meta-analysis, therefore it does not appear in the ranking. Treatment with denosumab results in increased occurrence of the adverse event ONJ (RR 3.45, 95% CI 1.06 to 11.24; per 1000 participants 30 more (1 more to 125 more); high-certainty evidence; 4 trials, 3006 participants) compared to no treatment/placebo. When comparing zoledronic acid to no treatment/placebo, the confidence intervals include the possibility of benefit or harm, therefore treatment with zoledronic acid probably neither reduces nor increases ONJ (RR 1.88, 95% CI 0.73 to 4.87; per 1000 participants 11 more (3 less to 47 more); moderate-certainty evidence; network based on 4 trials including 3006 participants). Compared to no treatment/placebo, treatment with zoledronic acid (RR 0.84, 95% CI 0.72 to 0.97) and denosumab (RR 0.72, 95% CI 0.54 to 0.96) may result in a reduction of the total number of SREs (per 1000 participants 75 fewer (131 fewer to 14 fewer) and 131 fewer (215 fewer to 19 fewer); both low-certainty evidence; 12 trials, 5240 participants). Treatment with zoledronic acid and denosumab likely neither reduces nor increases mortality when compared to no treatment/placebo (zoledronic acid RR 0.90, 95% CI 0.80 to 1.01; per 1000 participants 48 fewer (97 fewer to 5 more); denosumab RR 0.93, 95% CI 0.77 to 1.11; per 1000 participants 34 fewer (111 fewer to 54 more); both moderate-certainty evidence; 13 trials, 5494 participants). Due to insufficient reporting, no network meta-analysis was possible for the outcome quality of life. One study with 1904 participants comparing zoledronic acid and denosumab showed that more zoledronic acid-treated participants than denosumab-treated participants experienced a greater than or equal to five-point decrease in Functional Assessment of Cancer Therapy-General total scores over a range of 18 months (average relative difference = 6.8%, range -9.4% to 14.6%) or worsening of cancer-related quality of life.

AUTHORS' CONCLUSIONS

When considering bone-modifying agents as supportive treatment, one has to balance between efficacy and acceptability. Results suggest that Zoledronic acid likely increases both the proportion of participants with pain response, and the proportion of participants experiencing adverse events However, more trials with head-to-head comparisons including all potential agents are needed to draw the whole picture and proof the results of this analysis.